TW202301399A - Distortion optimized multi-beam scanning system - Google Patents

Abstract

A multi-beam charged particle inspection system and a method of operating a multi-beam charged particle inspection system for wafer inspection with high throughput and with high resolution and high reliability is provided. The method and the multi-beam charged particle beam inspection system comprises means for reduction and compensation of a scanning induced aberration, such as a scanning distortion of a collective multi-beam raster scanner for beamlets propagating at an angle with respect to the optical axis of the multi-beam charged particle inspection system.

Description

Distortion-optimized multi-beam scanning system

The present invention relates to a multi-beam charged particle detection system and a method of operating a multi-beam charged particle detection system. More particularly, the present invention relates to a multi-beam charged particle beam inspection system for wafer inspection with high resolution by an optimized scan for scanning a plurality of primary charged particle beamlet deflections sensor system, and a scan corrector for detection with very low distortion and high astigmatism correction. Through the method and the multi-beam charged particle beam detection system, high-precision wafer detection can be performed on a large imaging field.

With the continuous development of smaller and more complex microstructures such as semiconductor devices, further development and optimization of planar fabrication techniques and inspection systems for the fabrication and inspection of small-scale microstructures are required. The development and manufacture of semiconductor devices requires, for example, design verification of test wafers, while planar manufacturing technologies relate to process optimization for reliable high-throughput manufacturing. In addition, recently, semiconductor wafers are required to be analyzed for reverse engineering and customization and personalization of semiconductor devices. Therefore, there is a need for high-throughput inspection tools for testing on-wafer microstructures with high precision.

Typical silicon wafers used to manufacture semiconductor devices are up to 12 inches (300 mm) in diameter. Each wafer is divided into 30 to 60 repeating regions (“die”), with a maximum area of approximately 800 mm2. A semiconductor device includes a plurality of semiconductor structures fabricated in layers on a wafer surface by planar integration techniques. Due to all the processes involved, semiconductor wafers typically have a flat surface. The feature sizes of integrated semiconductor structures extend down to critical dimensions (CD) of 5 nm in the range of several µm, and in the near future even progressively smaller feature sizes, e.g. feature sizes below 3 nm (e.g. 2 nm) Or critical dimension (CD), or even below 1 nm. With the aforesaid small structural dimensions, dimensional defects of critical dimensions must be identified in a short time and over a large area. For several applications, the specification requirements for the measurement accuracy provided by the detection device are even higher, for example of the order of double or multiple. For example, the width of semiconductor features must be measured with sub-1 nm, such as 0.3 nm or even finer accuracy, and the relative position of semiconductor structures must be measured with sub-1 nm, such as 0.3 nm or even finer coverage accuracy. Sure.

Therefore, an object of embodiments of the present invention is to provide a charged particle system and a method for operating a high-throughput charged particle system, which can perform high-precision measurement of semiconductor features with an accuracy of less than 1 nm, less than 0.3 nm, or even 0.1 nm.

The latest development in the field of charged particle microscopy (CPM) is the multi-beam charged particle microscope (MSEM), for example a multi-beam scanning electron microscope is disclosed in patents US7244949 and US20190355544. In a multibeam electron microscope, the sample is illuminated by an array of electron beamlets containing, for example, 4 up to 10,000 electron beams (as primary radiation), such that each electron beam is separated from its next neighbor by a distance of 1 – 200 microns. For example, a multiple beam charged particle microscope has about 100 separate electron beams or beamlets arranged in a hexagonal array, where the electron beamlets are separated by a distance of about 10 µm. A plurality of beamlets of primary charged particles are focused through a common objective lens on the surface of the sample under study, such as a semiconductor wafer fixed on a wafer plate mounted on a movable platform. During irradiation of the wafer surface with a primary charged particle beamlet, interaction products (such as secondary electrons) originate from a plurality of intersection points formed by the primary charged particle beamlet focus, and the amount and energy of the interaction products depends on Material composition and morphology of the wafer surface. The interaction products form a plurality of secondary charged particle beamlets, which are collected by a common objective lens and guided to a detector arranged on the detector plane by a projection imaging system of the multi-beam detection system. The detector includes a plurality of detection areas, each area includes a plurality of detection pixels, and detects the intensity distribution of each of the plurality of secondary charged particle beamlets, and obtains, for example, a 100 µm × 100 µm image tiles. Prior art multiple beam charged particle microscopes contain a series of electrostatic and magnetic elements. At least some of the electrostatic and magnetic elements are adjustable, thereby adjusting the focus position and astigmatism of the plurality of secondary charged particle beams. Prior art multi-beam charged particle microscopes include at least one intersecting plane of primary or secondary charged particles. State-of-the-art multi-beam charged particle microscopes include detection systems that are easily tuned. Prior art multi-beam charged particle microscopes include at least one deflection scanner for scanning a plurality of primary charged particle beamlets across an area of the sample surface to obtain image tiles of the sample surface. Further details of the multi-beam charged particle microscope and the method of operation of the multi-beam charged particle microscope are disclosed in the patent application PCT/EP2021/061216 filed on April 29, 2021, which is incorporated herein by reference.

However, in charged particle microscopy for wafer inspection, it would be desirable to keep the imaging conditions stable so that imaging can be performed with high reliability and repeatability. The throughput depends on several parameters, such as the speed of the stage and realignment of new measurement points, and the measurement area per acquisition time itself, which is determined by the dwell time, resolution and number of beamlets. In addition, for multi-beam charged particle microscopy, time-consuming image post-processing is required. For example, the signal generated by the multi-beam charged particle microscope detection system must be digitally corrected before the images from multiple image sub-fields can be combined. The tiles fit together.

The plurality of primary charged particle beamlets may degenerate from regular grating positions within a grating configuration, such as a hexagonal grating configuration. Furthermore, the plurality of primary charged particle beamlets degrades from the regular raster position of the raster scan operation within the planar segment, and the resolution of a multi-beam charged particle detection system may vary and depend on the plurality of primary charged particle beamlets Individual scan positions for each individual beamlet in . To date, these scan-induced distortion differences between the plurality of primary charged particle beamlets have not been addressed. For a plurality of primary charged particle beamlets, each beamlet is incident on the intersecting body of the common scanning deflector at different angles, and each beamlet is deflected to a different exit angle, and each beamlet The beams pass through intersection volumes that share a scanning deflector on different paths. Therefore, each beamlet experiences a different distortion mode during the scanning operation. Single-beam dynamic correctors of the prior art are not suitable for mitigating distortions caused by any scanning of multiple primary beamlets. Patent US20090001267 A1 exemplifies calibration of a primary beam layout or a static grating pattern configuration of a multi-beam charged particle system comprising five primary charged particle beamlets. Three reasons for the deviation of the grating pattern are exemplified here: rotation of the primary beam layout, enlargement or reduction of the primary beam layout, and shift of the entire primary beam layout. Therefore, patent US20090001267 A1 considers the fundamental first-order distortion (rotation, magnification, global shift or displacement) of the static primary beam grating pattern formed by the static focal points of the plurality of primary beamlets. In addition, the patent US20090001267 A1 includes the calibration of first-order characteristics, deflection width and deflection direction of a convergent raster scanner, which is used for convergent raster scanning of a plurality of primary beamlets. Methods to compensate for these fundamental errors in a beam layout have been discussed here. For higher order distortions of static grating patterns, such as third order distortions, no solution is provided. Even after calibrating the secondary beam paths for the primary beam layout and selectivity, scanning distortions are introduced during scanning in each individual primary beamlet, which cannot be achieved by calibrating multiple primary beamlets. Static raster patterns to resolve.

Patent US20190088440 A1 proposes a porous plate in a multi-beam generating unit, which includes a plurality of openings with a plurality of electrodes for controlling the spot size and shape of a plurality of primary beam focal points. A dynamic means of controlling scanning distortion aberrations during image scanning is not provided here.

Dynamic correctors for single beam scanning systems are well known in the art. For example, it is well known how to dynamically compensate field curvature or field-dependent astigmatism of a single scanning electron beam during scanning of a single charged particle beam. By adding a cubic correction field term to the linear scan power of the scan deflector, third-order distortions induced by single-beam scanning are compensated. However, with prior art methods, dynamic aberrations are only corrected for a single beam passing through a scanning deflector intersection with a single beam path at a single angle of incidence and a single angle of exit relative to the optical axis.

Patent WO2007028596 A1 describes a perforated plate configuration configured for predetermined deflection of a plurality of primary charged particle beamlets. According to this configuration, a convergent deflection of a plurality of beamlets is performed and, for example, a fast switching of the operating mode can be achieved. In a specific example, the number of primary beamlets is varied by deflecting a plurality of beamlets into a beam stop. In one example, the individual deflection angles of each of the plurality of primary beamlets are determined by the mechanical layout of a pair of continuous perforated plates and applying an appropriate voltage difference between the two perforated plates. In this way, for example, a predetermined telecentricity of the plurality of beamlets is achieved. However, patent WO2007028596 A1 does not provide a solution to deal with the distortion caused by scanning. Patent WO2007028596 A1 mentions so-called blanking aperture arrays. Similar to the mode switching operation of patent WO2007028596 A1, the blanking aperture array is configured for fast binary switching operation of beamlets between on and off states, without providing for single and continuous scan deflection with high precision. any device.

Patent US 6897458 B2 shows an array of scanning deflectors for the deflection of a plurality of beamlets jointly scanning a multi-column system. Patent US20100248166A1 shows a converging scanning deflector for collective scanning deflection of a plurality of primary beamlets, combined with a static deflector array for adjusting the position of each primary beamlet. A static deflector array is used to adjust the static focus within the static raster configuration.

A problem of embodiments of the present invention is to provide a multi-beam charged particle detection system with components capable of high-throughput high-precision and high-resolution image acquisition. Another problem of an embodiment of the invention is to provide a multi-beam charged particle detection system which enables high-precision image acquisition of planar sections with deviations from predetermined grating positions within the specification requirements of the measurement task.

As demands for resolution and throughput continue to increase, conventional charged particle microscopes have reached their limits. Even in single-beam corrected charged particle microscopes, scan-induced aberrations such as residual scan-induced distortion, scan-induced astigmatism, or spherical aberration can reduce resolution and precision. The problem of an embodiment of the present invention is therefore to provide a charged particle detection system with components enabling high precision and high resolution image acquisition at high throughput. Another object of embodiments of the present invention is to provide means for correcting distortion differences caused by the scanning of multiple primary beamlets during an image scanning operation using a convergent deflection scanner of a multi-beam system. It is another object of embodiments of the present invention to compensate for distortion error variations of convergent deflection scanners or imaging optics for raster scanning and focusing multiple primary beams on the wafer surface.

Through specific embodiments of the present invention, aberrations caused by charged particle microscope scanning are reduced. The present invention provides an improved multi-beam charged particle microscope, an improved method of operating a multi-beam charged particle microscope and an improved method of calibrating a multi-beam charged particle microscope. The improvement reduces scan-induced aberrations, such as scan-induced distortions, induced during converged raster scanning of a plurality of J primary charged particle beamlets over the image field of a multi-beam charged particle microscope. An improved multibeam charged particle microscope contains means for compensating for scanning-induced aberrations. The means for compensating for scanning-induced aberrations comprises at least one electrostatic correction element configured, during use, to affect at least a first primary charged particle beamlet of a plurality of J primary charged particle beamlets; and controlling means for operating the electrostatic correcting element during use in synchronization with a collective raster scanning deflection of a plurality of J primary charged particle beamlets. The improved method of operation is configured to minimize scanning-induced aberrations, such as distortions, caused by scanning synchronously with the raster scanning of the plurality of J primary charged particle beamlets using a converging raster scanning deflector. The converging raster scan deflector is constructed and controlled to raster scan the plurality of J primary charged particle beamlets over a surface area of an object, such as a wafer, on an image field comprising the plurality of J image subfields. Each of the plurality of J primary beamlets is raster-scanned over a corresponding image sub-field. In each image sub-field with a lateral extension of about 8 μm to 12 μm, for example 10 μm, the primary charged particle beamlet and the plurality of J primary charged particle beamlets are deflected and scanned synchronously, with a resolution of about 0.5 nm to 3 nm, such as 1 nm or 2 nm, to expose a plurality of image pixel positions and obtain image information of the surface area. Using the embodiments of the present invention, the distortion caused by scanning each primary charged particle beamlet in the relative image sub-field is reduced. The distortion induced by scanning may be different for each primary charged particle beamlet within the relative image subfield. In one example, the difference between scanning-induced distortions within a plurality of image subfields has been reduced. In one example, scan-induced distortions of about 0.1 nm to 5 nm are determined in each of a plurality of image sub-fields by an improved calibration method, and control parameters are determined, applicable to operations with reduced scan-induced The distortion of multibeam charged particle microscopy has been improved. During operation of the improved multi-beam charged particle microscope, control parameters are applied to reduce distortions caused by the scanning of multiple J charged particle beamlets. Thereby, the distortion caused by scanning in the plurality of J-image subfields has been reduced. For example, the variance between scanning-induced distortions within a plurality of image subfields has been reduced. An improved calibration method is configured to determine scanning-induced distortion and derive control parameters for the control member. However, the present invention is not limited to distortions caused by scanning of a plurality of primary charged particle beamlets, but can also be applied to aberrations caused by scanning, such as changes or differences in astigmatism caused by scanning, focus position changes caused by scanning Change or difference, change or difference in spherical aberration of multiple J primary charged particle beamlets caused by scanning.

According to some specific embodiments of the present invention, the multi-beam charged particle microscope (1) for wafer inspection includes: a charged particle multi-beamlet generator (300), used to generate a plurality of primary charged particle beamlets (3); and an object irradiation unit (100), which is used to irradiate an image pattern arranged on the wafer surface (25) in the object plane (101) by a plurality of J primary charged particle beamlets (3) block (17.1), thereby generating a plurality of J secondary electron beamlets (9) emitted from the wafer surface (25) during use; and a detection unit (200), which has a projection system (205) and an image sensor (207), for imaging a plurality of J secondary electron beamlets (9) on the image sensor (207), and for acquiring the image of the wafer surface (25) during use The digital image of the image tile (17.1). The image tile (17.1) is divided into a plurality of J-image subfields (31), wherein each of the subfields corresponds to a primary charged particle beamlet. The multi-beam charged particle microscope (1) further includes a converging multi-beam raster scanner (110), which includes at least a first set of deflection electrodes and an intersecting body (189), the plurality of J primary charged particle The beam (3) passes through the intersecting body (189) during use; and a control unit (800) configured to provide at least a first scanning voltage difference VSp(t) to the first set of deflection electrodes during use , for convergent raster scanning of the plurality of J primary charged particle beamlets (3) in the first or p direction. The multi-beam charged particle microscope (1) further comprises means for individually compensating distortions caused by residual scanning of at least one first charged particle beamlet. The plurality of J primary charged particle beamlets comprises at least a first primary charged particle beamlet incident on the intersecting body (189) at a first inclination angle β1 and a second inclination angle β2 (different from the first inclination angle β1) incident on Second primary charged particle beamlet on intersecting body (189). During image scanning, the first primary beamlets are raster scanned over the first image subfield by the convergent multibeam raster scanner (110), and the second primary beamlets are rasterized by the convergent multibeam raster The scanner (110) is raster-scanned synchronously on the second image sub-field. Each image sub-field has a diameter of approximately 5 µm to 12 µm, eg 8 µm or 10 µm. By means of compensating distortions caused by residual scanning of at least one first primary charged particle beamlet, the difference in distortions caused by scanning between the first image subfield and the second image subfield is minimized. Thus, the two focal points of the first and second primary charged particle beamlets are raster-scanned during use at relative predetermined raster coordinates within the first and second sub-fields with a deviation below a predetermined threshold, for example 1 nm , below 0.3 nm or even below 0.1 nm. The means for compensating residual scanning induced distortions are configured to operate synchronously with the scanning deflection of the plurality of primary charged particle beamlets by the converging multi-beam raster scanner (110).

In one example, the means for compensating residual scan-induced distortions includes a compensator array for scan-induced distortions to individually compensate the first primary charged particle beamlet and the second primary charged particle beamlet Distortion caused by the residual scanning of multiple primary beamlets.

In an example, the means for compensating residual scanning induced distortion comprises means of a convergent raster (110) configured to produce a predetermined non-uniform scanning deflection field distribution in the intersecting volume (189) for Reduce the number of primary charged particle beamlets (including the first primary charged particle beamlet and the second primary charged particle beamlet) incident on the intersecting body (189) at a second inclination angle β2 deviating from the first inclination angle β1 ) The distortion caused by the scan,.

The multi-beam charged particle microscope comprises a raster scanner for at least one long-stroke scan deflection of the charged particle beamlets, which is supplied with a scan deflection voltage difference VSp(t) during use. The scanning deflection voltage difference VSp(t) is a time-varying voltage difference, such as a voltage ramp, applied to the raster scanner electrodes for convergent scanning deflection of a plurality of primary charged particle beamlets. The multi-beam charged particle microscope further comprises at least one first scan corrector element to which, during use, a first correction voltage difference VC1(t) is provided. The correction voltage difference VC1(t) is generated by the static voltage conversion unit according to the scanning deflection voltage difference VSp(t), which essentially reduces the scanning deflection voltage difference VSp(t) to at least one magnitude of the correction voltage difference VC1(t) , preferably two or more orders of magnitude. The static voltage conversion unit may include a programmable resistor series or array controlled by a plurality of control signals. Therefore, the correction voltage difference VC1(t) decreases in proportion to the scanning deflection voltage difference VSp(t). Thereby, a plurality of scan correction elements synchronized with the convergence raster scanner can be controlled at high speed. Typically, the scanning deflection has a temporal frequency of about 80 MHz to 200 MHz, for example 100 MHz. Using the static voltage conversion unit according to the embodiment of the present invention, the same time frequency of about 80 MHz to 200 MHz can be used to provide a plurality of synchronously corrected voltage differences to a plurality of calibration elements. Using an electrostatic voltage conversion unit according to an embodiment of the present invention for long stroke scanning deflection of each of the plurality of primary charged particle beamlets, for example a scanning deflection voltage difference VSp(t) of 10 μm Reduced to correct voltage difference VC1(t) for short-stroke scan deflection of each of the plurality of primary charged particle beamlets, eg 5 nm, to reduce distortion induced by individual scans of the primary charged particle beamlets. Thus, with specific embodiments of the present invention, the scan voltage deflectable over a large range is synchronized with the scan deflection voltage difference VSp(t) and has, for example, a frequency of 100 MHz Between the same scan frequency), a scan deflection voltage difference VSp(t) of about -100 V to 100 V is generated using a scan frequency of about eg 100 MHz.

In one example, the first scan corrector element is a first scan deflection element configured for short run deflection of at least a first primary charged particle beamlet synchronized with long run deflection. In one example, a plurality of charged particle beamlets are rastered by a first long-range raster scanner in the dimension of image sub-field D, e.g. +/- 5 μm, in parallel and synchronously with the long-range raster scanner , the distortion caused by the scanning of each of a plurality of primary beamlets is compensated by a plurality of short-stroke raster scanners to form a scanning corrector array, and the distortion caused by the maximum scanning is as high as +/- 5 nm. Each short-stroke scan deflection element used to reduce scanning-induced aberrations of individual beamlets is synchronized with the long-stroke scan operation, reducing scan power by approximately 3 orders of magnitude. Each small beam is focused on the predetermined scanning coordinate by the objective lens of the multi-beam charged particle microscope, and the precision is more than 3 orders of magnitude higher than that of the scanning coordinate. For example, a predetermined maximum scan coordinate at the maximum image height in the image subfield of 5.0 μm is achieved with an accuracy below 3 nm, preferably below 0.3 nm or even below 0.1 nm.

The multi-beam charged particle microscope may comprise a further scan corrector element to which, during use, a further correction voltage difference VCi(t) is provided which is synchronized and proportional to the scan deflection voltage difference VSp(t). Thereby, scanning-induced aberrations, such as scanning-induced telecentric aberration or scanning-induced astigmatism, are reduced during image scanning. In addition to the scanning deflection voltage difference VSp(t) for a long-stroke scanning deflection of the beamlet in the first or p direction, a second scanning deflection voltage difference VSq(t) may be provided to the long-stroke raster scanner to For long-stroke scan deflection in the second or q direction (perpendicular to the p direction). During use, an additional correction voltage difference VCj(t) is supplied to the scan corrector element, which is synchronized and proportional to the second scan deflection voltage difference VSq(t).

In a first embodiment, a multi-beam charged particle microscope includes a convergent multi-beam raster scanner for long-range scanning deflection of a plurality of primary charged particle beamlets. The first scan corrector element is disposed within the converged multi-beam raster scanner, and scanning-induced aberrations of the converged multi-beam raster scanner are minimized by the improved raster scanner design. In general, scanning-induced aberrations increase as the beamlet propagation angle β propagating through the intersecting volume of a converged multi-beam raster scanner increases. Using a modified deflection scanner design, an inhomogeneous variable electrostatic deflection field is generated whereby for beamlets propagating through the intersecting volume at an angle β, and especially for beamlets propagating through the intersecting volume at a large angle β, the scanning The resulting aberrations are minimized. In one example, a convergent multibeam raster scanner includes a set of deflection electrodes and at least a first set of correction electrodes configured to generate a correction field in addition to a scanning deflection field during use. The non-uniform correction field is a scanning correction field generated synchronously by the scanning voltage difference supplied to the set of correction electrodes and the scanning voltage difference supplied to the set of deflection electrodes. In one example, aberrations induced by additional scanning, such as those induced in the objective of a multi-beam charged particle microscope, are minimized by a predetermined non-uniform electrostatic deflection field. The set of correction electrodes and the scanning voltage difference supplied to the set of correction electrodes are configured to generate a predetermined non-uniform electrostatic deflection field which is synchronized with the scanning voltage difference supplied to the set of deflection electrodes, and the scanning of the multi-beam charged particle microscope Aberrations are minimized.

In the first specific embodiment, the multi-beam charged particle microscope (1) for wafer inspection includes a charged particle multi-beamlet generator (300), which is used to generate a plurality of primary charged particle beamlets ( 3); and an object irradiation unit (100), which is used to irradiate an image block ( 17.1), thereby generating a plurality of secondary electron beamlets (9) emitted from the wafer surface (25) during use; and a detection unit (200) having a projection system (205) and a an image sensor (207) for imaging a plurality of secondary electron beamlets (9) on the image sensor (207) and for acquiring the image of the wafer surface (25) during use Digital image of block (17.1). The multi-beam charged particle microscope (1) further comprises a converging multi-beam raster scanner (110) comprising at least a first set of deflection electrodes and an intersecting body (189), the plurality of primary charged particle beamlets the beam (3) passes through the intersecting body (189) during use; and a control unit (800) configured to provide at least a first scanning voltage difference VSp(t) to the first set of deflection electrodes during use, For converging and raster scanning a plurality of primary charged particle beamlets (3) in the first or p direction. The converging multi-beam raster scanner (110) is configured to produce a predetermined non-uniform scanning deflection field distribution in the intersecting volume (189) to deviate from the inclination of the optical axis of the multi-beam charged particle microscope (1) to reduce incident Aberrations caused by scanning of a charged particle beamlet on a volume (189).

In one example, the deflection electrodes of the first set of deflection electrodes consist of two spaced apart electrodes, and the control unit (800) is configured to provide, during use, first and second scanning voltage differences VSp1(t) and VSp2(t ) to the two spaced apart electrodes, wherein the first and second scan voltage differences VSp1(t) and VSp2(t) are different.

In an example, the convergent multibeam scanning raster scanner (110) of the multibeam charged particle microscope (1) comprises a second set of deflection electrodes for generating a second predetermined non-uniform scanning deflection field distribution during use, A plurality of primary charged particle beamlets (3) passing through a second predetermined non-uniform scanning deflection field distribution in the intersecting volume (189) for the plurality of primary charging in a second or q direction perpendicular to the first direction The particle beamlet (3) is scan deflected, and the control unit (800) is configured to provide, during use, at least a second scan voltage difference VSq(t) to the second set of deflection electrodes.

In one example, the shape and geometry of at least one first or second set of deflection electrodes of a converging multi-beam raster scanner (110) is adapted to intersect (189) a plurality of primary charged particle beamlets (3) ) of the profile. In one example, the cross section of the intersecting body (189) is hexagonal, and the first group or the second group of deflection electrodes are arranged on the periphery of the ellipse. In one example, the cross section of the intersecting body ( 189 ) is quadrilateral, and the first group or the second group of deflection electrodes are arranged on the periphery of the quadrilateral. Thereby, a predetermined field inhomogeneity of an inhomogeneous electrostatic field distribution can be generated.

In one example, the first set of deflecting electrodes and the second set of deflecting electrodes have different lengths in the average propagation direction of the plurality of primary charged particle beamlets (3). Thereby, a predetermined field inhomogeneity of an inhomogeneous electrostatic field distribution can be generated.

In an example, the convergent multibeam raster scanner (110) further includes a first set of correction electrodes (185, 193) configured to generate, during use, a predetermined scanning correction field that contributes to a predetermined non-uniform electrostatic field distribution. In one example, the electrodes (185.1, 185.2, 185.3, 185.4) of the first set of correction electrodes are arranged outside the intersecting body (189), in the space between the electrodes of the first set of deflection electrodes and the electrodes of the second set of deflection electrodes. In one example, the convergent multibeam raster scanner (110) further includes a second set of correction electrodes (187, 195) configured to produce a predetermined second scan during use that contributes to a predetermined non-uniform electrostatic field distribution correction field.

In one example, the converging multibeam raster scanner (110) is configured to adjust the lateral position of a predetermined non-uniform scanning deflection field distribution relative to the intersecting volume, and the control unit (800) is configured to provide a voltage offset during use to At least one of the first set of deflection electrodes or the second set of deflection electrodes. Thereby, the position of the predetermined non-uniform electrostatic field distribution is adjusted, and the aberration difference caused by scanning among the plurality of primary charged particle beamlets is minimized.

In one example, the multi-beam charged particle microscope (1) comprises a first static deflection system (701) arranged between the charged particle multi-beamlet generator (300) and the converging multi-beam raster scanner (110) , configured and constructed for adjusting the lateral position of the plurality of primary charged particle beamlets (3) relative to the intersection body (189). Thereby, the positions of the plurality of primary charged particle beamlets relative to the predetermined non-uniform electrostatic field distribution are adjusted, and the aberration difference caused by scanning among the plurality of primary charged particle beamlets is minimized.

In an example, the multi-beam charged particle microscope (1) comprises a second static deflection system (701) between the charged particle multi-beam belt generator (300) and the converging multi-beam raster (110), It is arranged and constructed for adjusting the average angle of incidence of the plurality of primary charged particle beamlets (3) at the entrance side of the intersecting body (189), and the average angle of incidence of the plurality of primary charged particle beamlets (3) is The average value of a plurality of angles of incidence for each individual primary beamlet. As a result, the difference in aberrations caused by scanning between the plurality of primary charged particle beamlets is minimized.

In a second embodiment, the object irradiation unit of a multibeam charged particle microscope comprises a first multibeam scanning corrector or a multibeam scanning correction system, such as an array of scanning distortion compensators, for individually compensating gratings or images Aberrations induced by each beamlet scan during scanning. During convergent rastering using the long stroke convergent multi-beam raster scanner, the first multi-beam scan correction system controls the position of the convergent raster on the sample surface. The converging multi-beam raster scanner concentrates and deflects a plurality of small beams of primary charged particles on each image subfield on the substrate surface, and the image subfield expansion is about D = 8 μm or 12 μm. The converging multi-beam scanning deflector may be an optimized multi-beam scanning deflector according to the first specific embodiment. The first multi-beam scanning correction system is configured as an array element having a plurality of apertures, and a plurality of deflection elements are arranged at the plurality of apertures, and each of the plurality of primary beamlets can pass through a different amount of scanning The deflection is an individual scan deflection synchronized with the converged raster scan of the plurality of primary beamlets by the converged multi-beam raster scanner. A multi-beam scan correction system, such as an array of scan distortion compensators, dynamically corrects residual scan distortion from about r = 1 nm to 5 nm to values below 0.3 nm, preferably below 0.2 nm, for each beamlet Or even below 0.1 nm.

According to the second specific embodiment of the present invention, a multi-beam charged particle microscope (1) for wafer inspection includes a charged particle multi-beamlet generator (300) for generating a plurality of primary charged particle beamlets beam (3); an object irradiation unit (100), used to irradiate an image block arranged on the wafer surface (25) in the object plane (101) by means of a plurality of primary charged particle beamlets (3) (17.1), thereby generating a plurality of secondary electron beamlets (9) emitted from the wafer surface (25) during use; a detection unit (200), which has a projection system (205) and a an image sensor (207) for imaging the plurality of secondary electron beamlets (9) on the image sensor (207) and for acquiring the image of the wafer surface (25) during use a digital image of the block (17.1); and a converging multi-beam raster scanner (110). The multi-beam charged particle microscope (1) further includes a multi-beam scanning correction system configured as a scanning distortion compensator array (601), which is arranged in a plurality of primary In the direction of propagation of charged particles, having a plurality of apertures, each of which is configured to transmit during use a plurality of primary charged particle beamlets relative to the primary charged particle beamlet, the plurality of apertures Each of them comprises a first deflection element for individually deflecting each relatively primary charged particle beamlet in a first or p direction; and a second deflection element for a second or q direction perpendicular to the first direction individually deflecting each of the relatively primary charged particle beamlets; and a control unit (800) configured, during use, to provide at least a first scanning voltage difference VSp(t) to the converging multi-beam rasterizer (110) , for scanning and deflecting a plurality of primary charged particle beamlets (3) in the first or p direction. The scanning distortion compensator array (601) further includes a scanning array control unit (622) having a first static voltage converting unit or array (611) configured to provide a plurality of first correction voltage differences to a plurality of first a deflection element; and a second electrostatic voltage conversion array (612), configured to provide a plurality of second correction voltage differences to the plurality of second deflection elements, so as to compensate the plurality of primary charged particle beamlets (3) along the Aberrations caused by scanning during scanning deflection in the first direction. The first static voltage conversion array (611) and the second static voltage conversion array (612) are coupled to the control unit (800), and are configured to control at least a plurality of the first static voltage conversion arrays (611) synchronized with the first scanning voltage difference VSp(t). A voltage differential component is supplied to each of the plurality of first and second deflection elements.

In an example, the control unit (800) is configured to provide, during use, a second scanning voltage difference VSq(t) to the converging multi-beam raster scanner (110) for scanning in a first direction perpendicular to the first direction. Scanning and deflecting a plurality of primary charged particle beamlets (3) in two or q directions. The first static voltage conversion array (611) and the second static voltage conversion array (612) are coupled to the control unit (800), and are configured to convert at least a plurality of first static voltages synchronized with the second scanning voltage difference VSq(t) Two differential voltage components are supplied to each of the plurality of first and second deflection elements. In one example, the first electrostatic voltage conversion array (611) is coupled to the control unit (800), and is configured to combine at least one first voltage component synchronized with the first scanning voltage difference VSp(t) and the second scanning A second voltage component synchronized with the voltage difference VSq(t) is supplied to each of the plurality of first deflection elements.

In one example, the first or the second static voltage conversion array (611, 612) is configured as a programmable resistor array.

In this way, the scanning positions of the multiple focal points of the multiple primary charged particle beamlets on the object surface are adjusted and synchronized with the image scanning, and the distortion difference caused by scanning between the multiple primary charged particle beamlets is minimized .

In a third specific embodiment, the object irradiation unit includes a second multi-beam scanning correction system, such as a scanning compensator array (602) for compensating the telecentric aberration caused by scanning, which is arranged on the first multi-beam Between the beam scanning correction system and the converging multi-beam raster scanner for individually controlling the angle of incidence of each individual beamlet on the sample surface. The second scanning compensator array (602) is used to compensate telecentric aberration caused by scanning, it is arranged near the intermediate image plane (321) of the multi-beam charged particle microscope (1), and has a plurality of deflection elements arranged in a plurality of A second scanning array control unit (622.2) on the aperture and having a second electrostatic voltage conversion array configured to provide a plurality of second correction voltage differences to each of the plurality of deflection elements to compensate for the Telecentric aberrations are induced by scanning each of the charged particle beamlets (3) once. Thereby, each beamlet of the plurality of primary beamlets can be individually deflected by different deflection amounts, synchronously with the collective deflection scanning of the plurality of primary beamlets by the convergent multi-beam deflection scanner. Thereby, the incident angles of the plurality of primary charged particle beamlets on the object surface are adjusted and synchronized with the image scanning, and the telecentric error caused by the scanning of each of the plurality of primary charged particle beamlets is minimized.

In one example, the multi-beam charged particle microscope (1) includes a further multi-beam scanning correction system configured as a scanning astigmatism array or a scanning lens array for compensating aberrations caused by scanning, such as scanning The resulting astigmatism, or deviation of the focal plane of each of the plurality of primary charged particle beamlets (3), during raster scanning of the plurality of primary charged particle beamlets (3). Thereby, the imaging aberration, such as astigmatism, of each of the plurality of primary charged particle beamlets on the object surface is adjusted in synchronization with image scanning, and the imaging aberration of each of the plurality of primary charged particle beamlets Scanning-induced imaging aberrations are minimized.

In a fourth embodiment, a method of operating a multi-beam charged particle microscope is provided, comprising the step of calibrating the charged particle microscope by measuring scanning-induced aberrations. In a further step, a static control parameter or signal is derived and a reduction factor for the correction electrode or the driving voltage difference VC(t) of the first or second scanning correction system is generated. The static control parameters and reduced drive voltage difference are provided to the first or second scan correction system. During image scanning, the scanning deflection voltage difference VS(t) is reduced by a reduction factor to at least a drive or correction voltage difference VC(t), which is supplied to the correction electrode, and scanning-induced aberrations are reduced during charged particle microscope operation .

According to a fifth embodiment of the present invention, a multi-beam charged particle microscope (1) for wafer inspection includes a charged particle multi-beamlet generator (300) for generating a plurality of primary charged particle beamlets beam (3); an object irradiation unit (100) for irradiating an image pattern arranged on a wafer surface (25) in the object plane (101) by means of a plurality of primary charged particle beamlets (3) block (17.1), thereby generating a plurality of secondary electron beamlets (9) emitted from the wafer surface (25) during use; a detection unit (200), which has a projection system (205) and a an image sensor (207) for imaging the plurality of secondary electron beamlets (9) on the image sensor (207) and for acquiring the image of the wafer surface (25) during use a digital image of a block (17.1); and a converging multi-beam raster scanner (110) having at least a first set of deflection electrodes and an intersecting body (189), the plurality of primary charged particle beamlets (3 ) through the intersecting body (189). The multi-beam charged particle microscope (1) further includes a first static deflection system (701) arranged between the charged particle multi-beam generator (300) and the converging multi-beam raster scanner (110), the structure of which is It is used to adjust the transverse position of the plurality of primary charged particle beamlets (3) relative to the intersection body (189). A control unit (800) configured to provide, during use, at least a first scanning voltage difference VSp(t) to the converging multi-beam raster scanner (110) for scanning deflecting a plurality of times in the first or p direction Charged particle beamlets (3). The converging multibeam raster scanner of a multibeam charged particle microscope is configured with an intersecting volume through which a plurality of primary charged particle beamlets propagate during use. According to a first particular embodiment, the converging multi-beam raster scanner is configured to generate a non-uniform electrostatic scanning deflection field in the intersecting volume. The aberrations induced by residual scanning depend on the laterally shifted positions and angles of incidence of the plurality of primary beamlets at the intersection of the converging multi-beam deflection scanner. In a fifth embodiment, a multi-beam charged particle microscope comprises a first static deflector upstream of a converging multi-beam deflection scanner. With this first static deflector, the laterally shifted position or angle of incidence of the plurality of primary charged particle beamlets is adjusted at the intersection volume. In one example, the object illumination unit of a multi-beam charged particle microscope comprises a second static deflector located between the first static deflector and the converging multi-beam raster for adjusting the primary beamlets Lateral shift position and angle of incidence. In the operation method, the moving position at the intersecting body is adjusted to a predetermined position by the first static deflector, and the average incident angle of the plurality of primary beamlets on the intersecting body is adjusted by the second static deflector.

In one example, the multi-beam charged particle microscope (1) comprises a second static deflection system (703) arranged between the charged particle multi-beamlet generator (300) and the converging multi-beam raster scanner (110) , the converging multi-beam raster scanner configured and constructed for adjusting the average angle of incidence of the plurality of primary charged particle beamlets (3) at the entrance side of the intersection body (189).

Thereby, imaging aberrations caused by scanning, such as distortion or astigmatism of each of the plurality of primary charged particle beamlets on the object surface, are reduced, synchronized with image scanning, and the plurality of primary charged particle beamlets The imaging aberrations caused by the scanning of each are minimized.

In a sixth embodiment, an improved multi-beam charged particle microscope is provided with a long-range raster scanner capable of lateral displacement or tilting. In one example, the lateral displacement is achieved by laterally shifting or tilting the electrostatic deflection field with respect to the intersecting volume by additional correction electrodes, or by providing a plurality of predetermined voltage offsets to the deflection electrodes and correction electrodes of the first embodiment of the present invention. shift or tilt. In an alternative example, the long-stroke raster scanner includes mechanical means including a guiding element or stage and at least one actuator for adjusting the lateral position or tilt angle of the deflection electrodes and selective correction electrodes relative to The electrostatic deflection field is volumetrically displaced at the point of intersection.

Thereby, imaging aberrations caused by scanning, such as distortion or astigmatism of each of the plurality of primary charged particle beamlets on the object surface, are reduced, synchronized with image scanning, and the plurality of primary charged particle beamlets The imaging aberrations caused by the scanning of each are minimized.

In a seventh embodiment, an improved multi-beam charged particle microscope combining the fifth and sixth embodiments is provided.

In one example, a method of operating a multi-beam charged particle microscope is provided. In a first step 1, the system is calibrated and the actual control parameters are stored in memory. In the second step 2, the beam positions of the plurality of primary beamlets at the intersection volume of the converging multi-beam raster scanner are adjusted. In an example according to the fifth embodiment, adjustment is achieved by a first static deflector and an optional second static deflector. In an example according to the sixth embodiment, the lateral displacement of the non-uniform deflection field is obtained by supplying an offset signal to a convergent multi-beam deflection scanner. In a third step, a control signal is provided. In one example, the correction field is generated by the control signal with the actual control parameters stored in step 1, and the scanning correction field is generated by the correction electrode providing a correction voltage difference synchronized with the scanning voltage difference. In one example, a plurality of correction voltage differences are generated by a static control signal, and each of the beamlets is individually deflected by a multi-beam scanning correction system. Thereby, the imaging aberration caused by scanning (such as the distortion or astigmatism of each of the plurality of primary charged particle beamlets on the object surface) is reduced and synchronized with the image scanning, and the plurality of primary charged particle beamlets are The imaging aberrations caused by the scanning of each of the beams are minimized.

In an eighth specific embodiment, at least two of the devices of the aforementioned first to seventh specific embodiments are combined, and the aberration caused by scanning is further reduced.

In a ninth embodiment of the present invention, there is provided a multi-beam charged particle microscope for wafer inspection, comprising a beamlet generator for generating at least one first primary charged particle beamlet, and An object irradiation unit for irradiating a sample surface image subfield arranged in the object plane by the first primary charged particle beamlet and the convergent raster scanner. The multi-beam charged particle microscope further comprises a control unit configured to provide, during use, at least a first scanning voltage difference VSp(t) to the convergent raster scanner for scanning in the first or p direction on the image subfield deflecting at least one first primary charged particle beamlet, the image subfield having a lateral extension of at least 5 μm, preferably 8 μm or greater, and at least one first scan corrector configured to generate during use for A first scanning correction field affecting the first primary charged particle beamlet. The control unit is configured to provide the first scan voltage difference VSp(t) to the first scan rectifier, and the first scan rectifier is configured to reduce the first time in synchronization with the focused scan deflection of the plurality of primary charged particle beamlets. Aberrations caused by the scanning of a small beam of charged particles. The first scan corrector comprises a static voltage conversion unit for converting the first scan voltage difference VSp(t) into at least one first scan correction voltage difference VCp(t), which is adapted to generate the first scan voltage difference VSp (t) Synchronized first scan correction field. The static voltage conversion unit may comprise at least one programmable resistor series configured to be programmed by a plurality of static control signals, so that the static voltage conversion unit is configured to generate a first scan correction voltage proportional to the first scan voltage difference VSp(t) Difference VCp(t). The control unit may comprise a first delay line configured to synchronize the first scanning correction field with the convergent raster scanning of the plurality of primary charged particle beamlets by the convergent raster scanner. The first scan corrector comprises at least one first deflection element configured to, during use, compensate distortions caused by scanning of the at least one first primary charged particle beamlet from about 0.5 nm to 5 nm to below 0.3 nm, preferably less than 0.2 nm or less than 0.1 nm. Likewise, other scanning-induced aberrations of multi-beam charged particle microscopy can be reduced, such as scan-induced astigmatism, which typically increases with the field height of the image subfield of the first primary charged particle beamlet And increase. In one example, the scanning-induced aberrations are residual scanning-induced distortions, and the first deflection elements are configured to individually compensate, during use, the aberrations caused by the scanning of the first primary charged particle beamlet in the first direction. The distortion is synchronized with the scanning deflection of the plurality of primary charged particle beamlets in the first direction by the converging raster scanner. The second deflection element may be configured to individually compensate, during use, for distortions caused by scanning of the first primary charged particle beamlets in the second direction, which is consistent with the passage of the plurality of primary charged particle beamlets through the converging raster scanner in conjunction with the first The scanning deflection of the first direction perpendicular to the two directions is synchronized. Typically, the scan-induced aberration is at least one of scan-induced distortion, scan-induced astigmatism, scan-induced telecentric aberration, scan-induced spherical aberration, or scan-induced hairline aberration. In one example, a multibeam charged particle microscope includes a static correction system for correcting for dispersion, field curvature, or static spherical aberration. In one example, the multi-beam charged particle microscope further includes a second scan corrector configured to reduce the second scan error during the first primary charged particle beamlet pass and raster scan with the raster scanner. The second scan-induced aberration is, for example, scan-induced astigmatism, scan-induced telecentric aberration, scan-induced spherical aberration, or scan-induced hair tail aberration (coma).

In a tenth specific embodiment of the present invention, a method for operating a multi-beam charged particle microscope (1) is provided, the microscope has a charged particle multi-beamlet generator (300), an object irradiation unit (100), a detector measurement unit (200), a convergent multi-beam raster scanner (110) for performing convergent raster scanning on a plurality of primary charged particle beamlets (3), and the convergent multi-beam raster scanner (110) A scanning distortion compensator array (601) in the upstream propagation direction of a plurality of primary charged particles, and a control unit (800). The method comprises the following steps: providing at least a first scanning voltage difference VSp(t) to the scanning array control unit (622); generating a plurality of voltage differential components from at least one first voltage difference VSp(t) and a plurality of static control signals; and providing a plurality of voltage difference components to a plurality of deflection elements of the scanning distortion compensator array (601), so as to individually scan and deflect each of the plurality of primary charged particle beamlets to compensate Distortions caused by scanning during the raster scan of the beamlet (3) convergent.

In an example, the operating method of the multi-beam charged particle microscope (1) further includes the following steps: Determining scanning-induced distortions by raster-scanning a plurality of primary charged particles on an image patch of a reference object; extracting a plurality of amplitudes of at least a linear portion of the distortion induced by each scan of the charged particle beamlet; deriving a plurality of static control signals from each of the plurality of amplitudes; and A scanning array control unit (622) providing a plurality of static control signals to the scanning distortion compensator array (601).

With various embodiments of the present invention, the aggregated raster scan operation of the plurality of primary beamlets is performed in parallel and synchronously to compensate for the aberrations caused by the scanning of individual primary beamlets. The aberrations caused by the scanning of individual beamlets are compensated by means of scanning correctors comprising a first scanning corrector in which a plurality of individual voltage differences are generated. The plurality of individual voltage differences are generated according to the voltage difference VSp(t) generated by the raster scanner for long stroke raster scanning in the first scanning direction. Accordingly, a multi-beam charged particle microscope for wafer inspection according to an embodiment comprises a generator for generating a plurality of primary beamlets, the beamlets comprising at least a first individual beamlet; an object an irradiation unit for irradiating an image patch on a sample surface arranged in the object plane with a plurality of primary beamlets, thereby generating a plurality of secondary electron beamlets emitted from the surface during use; and a A detection unit with a projection system and an image sensor is used to image a plurality of small beams of secondary electrons to the image sensor to obtain digital images of image blocks of the sample surface during use. The multi-beam microscope for wafer inspection according to various implementations further includes a converging multi-beam raster scanner comprising at least a first set of deflection electrodes and an intersecting volume, the plurality of beamlets traversing the intersecting body; at least one first scan modifier configured, during use, to generate a first scanned electrostatic field for influencing at least the first individual primary beamlet; and a control unit, configured to, during use, At least one first scanning voltage difference VSp(t) is supplied to the first set of deflection electrodes for convergent raster scanning of the plurality of primary beamlets in the first or p direction. The control unit is further configured to provide a first scan voltage difference VSp(t) to the first scan corrector configured to reduce aberrations induced by scanning of at least the first individual beamlet. In one example, the first scan corrector of the multi-beam charged particle microscope includes a first static voltage conversion unit for converting the first scan voltage difference VSp(t) into at least one first scan correction voltage difference VCp(t ) adapted to generate a first scan correction field synchronized with the first scan voltage difference VSp(t). In one example, the first static voltage conversion unit is configured to generate a first scan correction voltage difference VCp(t) proportional to the first scan voltage difference VSp(t). In one example, the static voltage conversion unit includes at least one programmable resistor series configured to be programmed by a plurality of static control signals. In one example, the control unit includes a first delay line configured to synchronize the first scan correction field with convergent raster scanning of the plurality of primary beamlets by the convergent multi-beam raster scanner.

In an example, a first scan corrector of a multi-beam charged particle microscope includes a plurality of deflection elements configured to compensate, during use, distortions induced by scanning of each of the plurality of primary beamlets. For example, the plurality of deflection elements includes a first deflection element configured, during use, to individually compensate for distortions caused by the scanning of the first individual beamlets in the first direction, which distortion is similar to that of the aggregated multi-beam raster scanner in The first direction is synchronized with the scanning deflection of the plurality of primary beamlets; and a second deflection element configured, during use, to individually compensate for distortions caused by the scanning of the first individual primary beamlets in the second direction, the The distortion is synchronized with the scanning deflection of the plurality of primary beamlets by the convergent multi-beam raster scanner in the first direction. The plurality of deflection elements further include a third deflection element configured to individually compensate during use for distortions caused by the scanning of the second individual beamlets in the first direction, the distortion being similar to that of the aggregated multi-beam raster scanner The scanning deflection of the plurality of primary beamlets is synchronized in the first direction. The plurality of deflection elements include other deflection elements configured to individually compensate during use for distortions caused by each individual scan of the beamlets in the first direction, and further deflection elements configured to individually compensate during use for each The distortion caused by the scanning of a single primary beamlet in a second direction, the distortion being synchronized with the scanning deflection of the plurality of primary beamlets in the first direction by a convergent multi-beam raster scanner. In one example, the static voltage conversion unit includes a plurality of programmable resistance series, each programmable resistance series is electrically connected to a deflection element among the plurality of deflection elements, and the plurality of programmable resistance series are formed by a plurality of statically controlled The signal-controlled programmable resistor array is configured to generate a plurality of scanning correction voltage differences VCap(i,t) during use, each scanning correction voltage difference being synchronized with the first scanning voltage difference VSp(t).

In one example, the first scan corrector comprises at least one correcting electrode configured to contribute during use to a non-uniform electrostatic field distribution generated in the intersecting volume of the convergent multi-beam deflection system, configured to reduce deviation from Aberrations induced by the scanning of individual primary beamlets incident on an intersecting body at an inclination angle of the optical axis of a multibeam charged particle microscope.

A method of operating a multi-beam charged particle microscope according to a specific embodiment comprises the following steps: generating a scanning voltage difference VSp(t) and supplying the scanning voltage difference VSp(t) to a convergent multi-beam raster scanner to use the convergent multi-beam The beam raster scanner converges and deflects and scans a plurality of primary beamlets in a first direction. The method further includes generating a first scan corrected voltage difference VCp(t) from the scan voltage difference VSp(t) at least synchronously with the scan voltage difference VSp(t), and providing the first scan corrected voltage difference VCp(t) to the scan A deflection element of the corrector for reducing aberrations caused by at least one scan of a single beamlet. In order to generate the first scan correction voltage difference VCp(t), the method includes the step of providing a plurality of static control signals to the scan calibrator to generate the first scan correction voltage difference VCp(t). In order to synchronize the scanning deflection of at least one beamlet with the reduction of aberrations induced by the scanning of at least one individual beamlet, the method further comprises the step of correcting the voltage difference VCp(t) and the scanning voltage difference VSp in the first scan (t) steps that generate a predetermined time delay between.

The multi-beam charged particle microscope according to the above-described embodiments comprises an electrostatic voltage conversion array configured to provide at least one scan correction voltage difference to At least one scan corrector or compensation element. The electrostatic voltage conversion array is configured to provide scan correction voltage differences from at least one common, long-stroke scan voltage difference, thereby maintaining the dependence of scan induced aberrations on scan position (p, q) in the image field during image scanning. In one example, the static voltage conversion array is programmable by a plurality of static control signals. The multi-beam charged particle microscope further includes a control unit for providing a plurality of static control signals to the static voltage conversion array. In an example, the control unit is configured to generate a plurality of static control signals from calibration measurements. In an example, the control unit is configured to generate a plurality of static control signals from calibration measurements.

The control unit is configured to provide, during use, at least a first scanning voltage difference VSp(t) to the first set of deflection electrodes for convergent raster scanning of the plurality of primary charged particle beamlets in the first or p direction. The control unit is further configured to provide a first scan voltage difference VSp(t) to the first scan corrector configured to reduce aberrations induced by at least the first single beamlet scan. In one example, the first scan corrector of the multi-beam charged particle microscope includes a first static voltage conversion unit for converting the first scan voltage difference VSp(t) into at least one first scan correction voltage difference VCp(t ) adapted to generate a first scanning electrostatic field synchronized with the first scanning voltage difference VSp(t). The first static voltage conversion unit is configured to generate a first scan correction voltage difference VCp(t) proportional to the first scan voltage difference VSp(t).

An exemplary static voltage translation array is implemented as a programmable resistor array configured to be programmed by a plurality of static control signals. Through the programmable resistor array, the dynamic signal required to compensate for the scan distortion of each of the plurality of beamlets is reduced to only two scan control voltage differences VCp(t) and VCq(t), which are generated from the scan control unit. The voltage difference VSp(t) and VSq(t) is obtained for driving the convergent multibeam raster. Through the two control voltage differences VCp(t) and VCq(t), compensation or correction of scanning-induced aberrations, such as scanning-induced distortion, scanning-induced telecentric aberration, or scanning-induced astigmatism, is realized. In one example, the control unit includes a first delay line configured to synchronize the first scan corrector field with the convergent raster scanning of the plurality of primary beamlets by the convergent multi-beam raster scanner. The compensation or correction is directly connected through the delay line, so it directly depends on the scanning voltage difference VSp(t) and VSq(t), so the compensation or correction of the scanning-induced aberration is synchronized with the scanning operation and with the scanning of each image sub-field The coordinates (p,q) are proportional. In one example, the linear part of the scan-induced aberration constituting the main part of the scan-induced aberration is controlled by the difference between the control voltage differences VCp(t) and VCq(t) and the scan voltage differences VSp(t) and VSq(t). ratio to compensate. For each of the plurality of image subfields and corresponding beamlets, the amplitude of the linear part of the aberration caused by scanning is different, and the required control signal comes from the common control voltage difference VCp(t) and VCq(t), for example Through the programmable resistor array, a relative proportional voltage difference is thus generated for each electrode from the common control voltage difference VCp(t) and VCq(t). Each individual voltage difference supplied to, for example, the electrodes of a scanning distortion compensator array or the correction electrodes of a converging multi-beam raster scanner is coupled directly to a common control voltage difference VCp( t) and VCq(t). For example, the individual voltage differences supplied to the electrodes to compensate for aberrations induced by the scanning of individual beamlets are controlled by a plurality of predetermined static control signals, thus programming each sequence of programmable resistors. Thus, the individual voltage differences are also proportional to the scan voltage differences VSp(t) and VSq(t) and thus to the scan coordinates (p,q) in each image subfield. Propagation effects (i.e. time delays of different deflectors) are reduced and with 50 MHz and High dynamic compensation of aberrations caused by scanning with a larger dynamic range, eg around 80 MHz, or even 100 MHz is possible. Static delay lines are implemented to synchronize the compensation of scanning-induced aberrations with the scanning deflection of the plurality of primary charged particle beamlets and the converging multi-beam deflection system. Furthermore, the conductive connections for supplying the electrodes with a highly dynamic correcting voltage difference can be designed as high-frequency connections and shielded, for example, by a ground wire and avoid interference or radiation losses.

In an example, a scan corrector of a multi-beam charged particle microscope includes a plurality of deflection elements configured to compensate, during use, for distortions induced by scanning of each of the plurality of primary beamlets. For example, the plurality of deflection elements includes a first deflection element configured, during use, to individually compensate for distortions caused by scanning of the first individual beamlets in a first direction, which distortions are similar to those of the aggregated multi-beam raster scanner in the first direction. synchronizing the scanning deflection of the plurality of primary beamlets in one direction; and comprising a second deflection element configured to individually compensate during use for distortions caused by scanning of the first individual primary beamlets in the second direction, the distortion being related to The converged multi-beam raster scanner synchronizes the scanning deflection of the plurality of primary beamlets in the first direction. The plurality of deflection elements further include a third deflection element configured, during use, to individually compensate for distortions caused by the scanning of the second individual beamlets in the first direction, which is consistent with the converged multi-beam raster scanner The first direction synchronizes the scanning deflection of the plurality of primary beamlets. In one example, the static voltage conversion unit includes a plurality of programmable resistor sequences, each programmable resistor sequence is connected to a deflection element among the plurality of deflection elements, and the plurality of programmable resistor sequences form a plurality of static control signals The controlled programmable resistor array is configured to generate a plurality of scanning correction voltage differences VCap(i,t) during use, each scanning correction voltage difference being synchronized with the first scanning voltage difference VSp(t).

In one example, the first scan corrector comprises at least one correcting electrode configured to contribute during use to a non-uniform electrostatic field distribution generated in the intersecting volume of the convergent multi-beam deflection system, configured to reduce Aberrations induced by the scanning of individual beamlets propagating in at least a portion of the intersecting volume at angles offset from the optical axis of a multibeam charged particle microscope.

A method of operating a multi-beam charged particle microscope according to a specific embodiment comprises the following steps: generating a scanning voltage difference VSp(t) and providing the scanning voltage difference VSp(t) to a convergent multi-beam grating scanner to use the convergent multi-beam The beam raster scanner converges and deflects and scans a plurality of primary beamlets in a first direction. The method further includes generating a first scan correction voltage difference VCp(t) from the scan voltage difference VSp(t) at least synchronously with the scan voltage difference VSp(t), and providing the first scan correction voltage difference VCp(t) to the scan A deflection element of the corrector for reducing aberrations caused by scanning of at least one individual beamlet of the plurality of primary beamlets. In order to generate the first scan correction voltage difference VCp(t), the method includes the step of providing a plurality of static control signals to the scan corrector to generate the first scan correction voltage difference VCp(t). In order to synchronize the reduction of aberrations induced by the aggregated raster scanning of a plurality of primary beamlets with the scanning of at least one individual beamlet, the method further comprises correcting the voltage difference VCp(t) and the scanning voltage difference VSp in the first scan (t) steps that generate a predetermined time delay between.

In some examples, the scanning of the plurality of primary charged particle beamlets above the wafer surface is accomplished in only the first direction by the first convergent multi-beam raster scanner (110), and the wafer is moved along the wafer stage Move continuously in the second direction. In this example, the scan voltage difference VSq(t) along the second direction is at a constant voltage difference or zero.

The convergent multi-beam raster scanner for convergent deflection scanning of a plurality of primary charged particles according to the first embodiment produces reduced scanning-induced aberrations during use. Through the optimal design of the converged multi-beam raster scanner, a predetermined non-uniform field distribution is generated for deflection scanning, and the aberration caused by scanning is reduced. The aberrations induced by the residual scanning of each beamlet are different because the angle of propagation through the intersecting volumes of the converging multi-beam raster is different for each beamlet. In general, even if nonlinear scanning aberrations are minimized eg for a number of striped field points with similar distances from the optical axis, there will be eg residual scanning distortions for other field points corresponding to other beamlets. Therefore, the present invention is very important for multi-beam systems comprising more than one beam passing through a deflection scanner at different symmetrical positions, and for large fields of view such as multi-beam scanning electron microscopes. The angular spread of the beam angle at the scanning deflector corresponds to the field patch size divided by the objective focal length f. Since the objective focal length f cannot be made very large, and is practically limited by the objective diameter, the angular spread of multi-SEM scanners is much larger compared to single-beam scanners. The field patch size is eg 10 times higher compared to a typical single beam SEM. For a superposition or absolute position accuracy of 1 nm, the convergent multibeam raster scanner provides a ratio of 100.000:1. Therefore, 16-bit resolution is not enough, at least 32-bit corresponding to 32-bit DAC conversion is required to generate the deflection voltage differences VSp(t) and VSq(t).

Typically, the objective lens consists of a thick magnetic lens. The traversal paths of the plurality of primary charged particle beamlets are different for all field points and will change during the scanning process. Thereby, during scanning, the objective introduces residual aberrations and aberration differences between the individual beamlets. Scanning-induced distortion in the image subfield is reduced during image scanning through an improved design of the deflection electrodes. For example, with deflection electrodes separated into deflection electrode pairs, deflection electrodes with modified azimuth or longitudinal extension, or with deflection electrodes optimized or tuned for a raster configuration of a plurality of primary charged particle beamlets, image subfields The distortion caused by scanning in the field is reduced. Scan distortion can be further reduced by using additional correction electrodes. In a preferred example, the performance of the deflection yoke is optimized together with imaging aberrations caused by other optical elements such as the objective lens (102), and the scanning in the plurality of image subfields of each primary charged particle beamlet is caused by The distortion is further reduced. Due to the additional degrees of freedom of more deflection electrodes and correction electrodes, manufacturing tolerances or drifts of the deflection yoke can be compensated by adjusting the multiple voltages applied to the multiple deflection electrodes and the multiple correcting electrodes. The modified deflection yoke according to the first embodiment may reduce residual scanning induced distortions by eg at least 15%, at least 20% or even 30%. A residual scan distortion of eg lower than 1.5 nm is achieved with the first embodiment, compared to uncorrected scan distortion using a conventional deflection system of eg around 2 nm. This allows further improvements, but increases sensitivity to alignment errors, noise and drift. Additional improvements in imaging performance are described in a second specific embodiment. Scan distortion is thereby reduced by at least 80%, achieving a residual scan-induced distortion of less than 0.3 nm. By means of any of the above-described embodiments, aberrations induced by the scanning of the self-converging multibeam raster scanner and other optical elements, such as the objective lens, are compensated and effectively minimized. By combining the specific embodiments described in the eighth specific embodiment, the residual scanning distortion is reduced by at least 90%, such as 95%, and the residual scanning distortion is eg lower than 0.2 nm, preferably lower than 0.1 nm or even lower.

With various embodiments of the present invention, the aberrations caused by the scanning of a single beamlet are compensated in parallel and synchronously with the convergent raster scanning of the plurality of beamlets. Aberrations caused by a single scan of the beamlets are compensated by scan correctors comprising a first scan corrector in which a plurality of individual voltage differences is provided or in which a plurality of individual voltage differences are generated. A plurality of individual voltage differences for correcting or compensating scanning-induced aberrations are generated from the voltage differences VSp(t) and VSq(t) produced by the convergent multi-beam raster scanner for convergent raster scanning. Embodiments of the present invention provide a solution for minimizing scanning-induced aberrations, especially distortions caused by multi-beam charged particle microscopy. The imaging performance of conventional multibeam charged particle microscopes is degraded by scanning distortion [dp,dq], i.e., scanning-induced distortions that produce overlay errors and differences in pixel pitch or pixel size on top of digital images of image tiles on the wafer surface. Variety. For systems with a large number of J beamlets, the distortion induced by scanning increases and can reach values of 2 nm to 5 nm or higher. In addition to scan distortion, other scan-induced imaging aberrations, such as scan astigmatism or scan defocus, degrade imaging performance. In an aspect of an embodiment of the present invention, the required scan correction is achieved by reducing the enormous data rate corresponding to the scan-induced aberrations, and the scan aberrations can be compensated for at high speed. The correction or compensation of scan-induced aberrations is determined by normalizing each of the plurality of image sub-fields by extending the scan-induced aberrations in the set of predetermined scan-induced aberration vectors for each image sub-field A plurality of amplitudes of the aberration vector caused by scanning is realized, and a plurality of electrostatic correction or compensation control signals are derived from the amplitude of each image sub-field, and the control voltage difference of the electrostatic compensation or correction element is obtained, and the control voltage difference proportional to the common scan voltage difference VSp(t), VSq(t) in the first and second scan directions (p,q) in each image subfield, whereby the proportionality is controlled by static correction or compensation Signal-controlled electrostatic voltage conversion array to achieve. For example, the plurality of J linear scans in the plurality of J image subfields are distorted by scanning the plurality of J primary charged particle beamlets in parallel by using a converged multi-beam raster scanner, at least by using Compensation is performed by an electrostatic correction field generated by at least one electrostatic compensation or correction element, whereby each correction voltage difference of the at least one electrostatic compensation or correction element of each of the J beamlets is provided by an electrostatic voltage conversion array. The static voltage conversion array is implemented as a programmable resistor array, for example, including a plurality of programmable resistor sequences, with two high dynamic driving signals proportional to the common scanning voltage difference VSp(t) and VSq(t), for a plurality of J Parallel scanning of primary charged particle beamlets in first and second directions (p,q) using a convergent multi-beam raster scanner.

Further details are described in the examples of specific embodiments. Further specific embodiments include combinations or variations of the foregoing examples and specific embodiments.

In the exemplary embodiments described below, functionally and structurally similar components are denoted by the same or identical reference numerals as much as possible.

Figure 1 is a schematic diagram illustrating the basic features and functions of a multi-beam charged particle microscope system 1 according to some embodiments of the present invention. It is to be noted that the symbols used in the figures do not represent the physical configuration of the illustrated components, but have been chosen to symbolize their respective functions. The type of system shown is a multi-beam scanning electron microscope (MSEM or Multi-SEM), which uses a plurality of primary electron beamlets 3 on a surface of an object 7, such as with a top surface 25 located in the object plane 101 of an objective 102 A plurality of primary charged particle beam spots 5 are generated. For simplicity, only five primary particle beamlets 3 and five primary particle beam spots 5 are shown. Electrons or other types of primary charged particles such as ions, especially helium ions, may be used to achieve the properties and functionality of the multi-beamlet charged particle microscope system 1 .

The microscope system 1 includes an object irradiation unit 100 , a detection unit 200 , and a beam splitter unit 400 for separating the secondary charged particle beam path 11 from the primary charged particle beam path 13 . The object irradiation unit 100 comprises a charged particle multi-beam generator 300 for generating a plurality of primary charged particle beamlets 3 and adapted to focus the plurality of primary charged particle beamlets 3 in the object plane 101, wherein the wafer 7 The surface 25 is positioned by the sample stage 500.

The primary beam generator 300 generates a plurality of small primary charged particle beam spots 311 in the intermediate image surface 321 , which is usually a spherically curved surface, so as to compensate the field curvature of the object irradiation unit 100 . The primary beam generator 300 comprises a source 301 of primary charged particles such as electrons. The primary charged particle source 301 emits a divergent primary charged particle beam 309 which is collimated by at least one collimating lens 303 to form a collimated beam. The collimating lens 303 is usually composed of one or more electrostatic or magnetic lenses, or a combination of electrostatic and magnetic lenses. The collimated primary charged particle beam is incident on the primary multi-beam forming unit 305 . The multi-beam forming unit 305 basically comprises a first perforated plate 306 . 1 irradiated by a primary charged particle beam 309 . The first perforated plate 306.1 includes a plurality of holes in a grating configuration for generating a plurality of small beams 3 of primary charged particles, and these small beams are generated by passing the collimated primary charged particle beam 309 through the plurality of holes . The multi-beamlet forming unit 305 comprises at least further perforated plates 306.2 and 306.3, which are located downstream of the first perforated plate 306.1 with respect to the direction of movement of the electrons in the electron beam 309. For example, a second perforated plate 306.2 has the function of a microlens array and is preferably set to a defined potential to adjust the focus position of the plurality of primary beamlets 3 in the intermediate image surface 321 . A third active multi-well plate configuration 306.3 (not shown) includes a separate electrostatic element for each of the plurality of wells to separately affect each of the plurality of beamlets. Active porous plate configuration 306.3 consists of one or more porous plates with electrostatic elements, such as circular electrodes for microlenses, multipolar electrodes, or a series of multipolar electrodes to form a static deflector array, microlens array, or aberration Compensator (Stigmator) array. The multi-beamlet forming unit 305 is composed of the adjacent first electrostatic field lens 307, and together with the second field lens 308 and the second perforated plate 306.2, focuses a plurality of primary charged particle beamlets 3 on the intermediate image plane 321 or near. Downstream of the multi-beamlet forming unit 305, a scanning distortion compensator array 601 according to a second embodiment of the present invention may be arranged. The scanning distortion compensator array 601 is described in more detail below.

In or near the intermediate image plane 321 , a static beam steering perforated plate 390 configures a plurality of holes with electrostatic elements (eg deflectors) to steer each of the plurality of charged particle beamlets 3 respectively. The apertures of the beam steering perforated plate 390 are configured with a larger diameter to allow the passage of the plurality of primary charged particle beamlets 3 even when the focal point of the primary charged particle beamlets 3 deviates from the intermediate image plane or its designed position in this way. Near the intermediate image plane, a scanning compensator array 602 for compensating the telecentric error caused by scanning according to the third embodiment of the present invention has been arranged. The scan compensator array 602 used to compensate for scan-induced telecentricity errors is described in more detail below. In one example, beam steering multi-well plate 390 and scanning compensator array 602 may also be formed as a single multi-well element.

The focal points of the primary charged particle beamlets 3 passing through the intermediate image plane 321 are imaged by the field lens group 103 and the objective lens 102 in the image plane 101 in which the investigation surface 25 of the object 7 is positioned. The object illumination system 100 further comprises a converging multi-beam raster 110 near the first beam intersection 108 so that the plurality of charged particle beamlets 3 can be directed along a direction perpendicular to the direction of beam propagation or to the optical axis 105 of the objective lens 102. direction deflection. In the example of FIG. 1 , the optical axis 105 is parallel to the z direction. The converged multi-beam raster scanner 110 according to the first embodiment of the present invention is optimized for the distortion caused by the minimum scanning of a plurality of primary charged particles through the converged multi-beam raster scanner 110 at different propagation angles β . Details of the converged multi-beam raster scanner 110 according to the first embodiment are described below. The objective lens 102 and the converging multi-beam raster scanner 110 are centered on the optical axis 105 of the multi-beamlet charged particle microscope system 1 perpendicular to the wafer surface 25 . The wafer surface 25 disposed in the image plane 101 is then raster scanned with a convergent multibeam raster scanner 110 . In this way, a plurality of primary charged particle beamlets 3 that form a plurality of beam spots 5 configured in a raster configuration are scanned synchronously on the wafer surface 101 . In one example, the grating configuration of the focal points 5 of the plurality of primary charged particle beamlets 3 is a hexagonal grating of about one hundred or more primary charged particle beamlets 3 . The primary beam spot 5 has a distance of about 6 µm to 15 µm and a diameter of less than 5 nm, eg 3 nm, 2 nm or even smaller. In one example, the beam spot size is about 2 nm, and the distance between two adjacent beam spots is 8 µm. At each scanning position of each of the plurality of primary beam spots 5, a plurality of secondary electrons are respectively generated, and a plurality of secondary electron small holes are formed with the same grating configuration as the primary beam spot 5. Beam 9. The intensity of the secondary charged particles generated at each beam spot 5 depends on the intensity of the impinging primary charged particle beamlets 3, the illumination of the opposing spot and the material composition and morphology of the object 7 beneath the beam spot 5. The small secondary charged particle beam 9 is accelerated by the electrostatic field generated by the sample charging unit 503 , collected by the objective lens 102 , and directed to the detection unit 200 by the beam splitter 400 . The detection unit 200 images the small secondary electron beam 9 onto the image sensor 207 to form a plurality of secondary charged particle spots 15 therein. The detector includes a plurality of detector pixels or individual detectors. The intensity is detected separately for each of the plurality of secondary charged particle beam spots 15, and the material composition of the wafer surface 25 is detected with high throughput and high resolution for large image tiles. For example, for a 10 x 10 beamlet grating with 8 µm pitch, one image scan with convergent multi-beam raster scanner 110, with an image resolution of, for example, 2 nm or less, yields an image pattern of approximately 88 µm by 88 µm piece. For example, the image tiles are sampled at half the beam spot size, so for each beamlet, the number of pixels per image row is 8000 pixels, showing the image tiles produced by 100 beamlets. The digital dataset consists of 6.4 billion pixels. The control unit 800 collects image data. Details of image data collection and processing using eg parallel processing are disclosed in German patent application 102019000470.1 and US patent US 9.536.702, which are incorporated herein by reference.

A plurality of secondary electron beamlets 9 pass through the first converging multi-beam raster scanner 110, are deflected by the first converging multi-beam raster scanner 110 and are guided by the beam splitter unit 400 to follow the detection unit 200 The secondary particle beam path 11 . The plurality of secondary electron beamlets 9 travel in opposite directions to the primary charged particle beamlets 3, and the beam splitter unit 400 is configured to separate the secondary particle beam paths 11 from the primary particle beamlets, usually by means of a combination of magnetic or electromagnetic fields. The beam paths 13 are separated. Optionally, additional magnetic correction elements 420 are present in either the primary particle beam path or the secondary particle beam path. The projection system 205 further includes at least one second convergent rasterizer 222 connected to the projection system control unit 820 . The control unit 800 is configured to compensate residual differences in positions of the plurality of focal points 15 of the plurality of secondary electron beamlets 9 , so that the positions of the plurality of secondary electron focal points 15 remain constant on the image sensor 207 .

The projection system 205 of the detection unit 200 comprises additional electrostatic or magnetic lenses 208, 209, 210 of the plurality of secondary electron beamlets 9 and a second cross over 212 in which an aperture 214 is located. In one example, the aperture 214 further includes a detector (not shown), which is connected to the projection control unit 820 . The projection system control unit 820 is further connected to at least one electrostatic lens 206 and the third deflection unit 218 . The projection system 205 further comprises at least one first porous modifier 220 having apertures and electrodes for separately influencing each of the plurality of secondary electron beamlets 9, and an optional further active element 216, such as a connection to the multipole element of the control unit 800 .

The image sensor 207 is composed of an array of sensing areas, and the sensing area pattern is compatible with the raster configuration of the secondary electron beamlets 9 focused onto the image sensor 207 by the projection lens 205 . This enables detection of each individual secondary electron beamlet independently of other secondary electron beamlets incident on image sensor 207 . A plurality of electrical signals are established and converted into digital image data, and processed by the control unit 800 . During image scanning, the control unit 800 is configured to trigger the image sensor 207 to detect a plurality of timely resolved intensity signals from the plurality of secondary electron beamlets 9 at predetermined time intervals, and the digital images of the image tiles are accumulated and All scan positions from the plurality of primary charged particle beamlets 3 are stitched together.

The image sensor 207 shown in FIG. 1 can be an array of electronic sensitive detectors, such as CMOS or CCD sensors. Such electron-sensitive detector arrays may comprise electron-to-photon conversion cells, such as scintillator elements or arrays of scintillator elements. In one example, the image sensor 207 can be configured as an electron-to-photon conversion unit or a scintillator plate disposed in the focal plane of the plurality of secondary electron particle spots 15 . In this example, image sensor 207 may further include a relay optics system for secondary charging on dedicated photon detection elements such as photomultiplier tubes or avalanche photodiodes (not shown). At the particle spot 15, the photons generated by the electron-to-photon conversion unit are imaged and guided. The above-cited image sensor is disclosed in US Pat. No. 9,536,702. In one example, the relay optical system further includes a beam splitter for splitting and directing light to the first slow light detector and the second fast light detector. The second fast photodetector is formed, for example, by a photodiode array such as an avalanche photodiode, and the speed of this detector is fast enough to resolve the plurality of primary charged particle beamlets 3 according to the scanning speed Image signal of the secondary electron beamlet 9 . The first slow light detector is preferably a CMOS or CCD sensor, which provides a high resolution sensor data signal to monitor the focal point 15 or the plurality of secondary electron beamlets 9 and control the multi-beam charged particle microscope operate.

In one example, the primary charged particle source is implemented in the form of an electron source 301 having an emitter tip and extraction electrodes. When primary charged particles other than electrons are used, such as helium ions, the configuration of the primary charged particle source 301 may be different from that shown. Primary charged particle source 301 and active perforated plate configurations 306 . 1 .

During the capture of image blocks by scanning the plurality of primary charged particle beamlets 3, the platform 500 is preferably not moved, and after capturing the image blocks, the platform 500 is moved to the next image block to be captured place. In an alternative embodiment, the stage 500 is continuously moved in the second direction while capturing images by scanning the plurality of primary charged particle beamlets 3 in the first direction with a converged multi-beam raster scanner 110 . Stage movement and stage position are monitored and controlled by sensors known in the industry, such as laser interferometers, grating interferometers, confocal microlens arrays, or similar instruments.

FIG. 2 is a more detailed description of the method of inspecting wafers by acquiring image blocks. The wafer is placed with its wafer surface 25 in the focal plane of the plurality of primary charged particle beamlets 3 and with the center 21.1 of the first image segment 17.1. The predetermined positions of the image tiles 17.1...k correspond to inspection sites on the wafer for semiconductor feature inspection. This application is not limited to the wafer surface 25 , but is also applicable, for example, in photolithography masks for semiconductor manufacturing. Accordingly, the term "wafer" should not be limited to semiconductor wafers, but encompasses general objects used in or produced during semiconductor manufacturing.

From the detection file in the standard file format, the predetermined positions of the first detection part 33 and the second detection part 35 are loaded. The predetermined first detection site 33 is divided into a plurality of image blocks, such as a first image block 17.1 and a second image block 17.2, and the first center position 21.1 of the first image block 17.1 is in the multi-beam charged particle The microscope 1 is aligned below the optical axis 105 for the first image acquisition step of the inspection task. The first center of the first image tile 21.1 is selected as the origin of the first local wafer coordinate system for acquiring the first image tile 17.1. Methods of aligning wafer 7 to register wafer surface 25 and generate a local coordinate system of wafer coordinates are well known in the art.

A plurality of primary beamlets 3 are distributed in each image block 17.1...k in a regular raster configuration, and are scanned by a raster scanning mechanism to generate a digital image of the image block. In this example, a plurality of primary charged particle beamlets 3 are arranged in a rectangular grating configuration, with N primary beam spots 5.11, 5.12 to 5.1N in the first row with N beam spots, and the Mth row It has beam spot 5.11 to beam spot 5.MN. For simplicity, only the number of spots M=5 by N=5 is shown, but the number of spots J=M by N could be larger, for example J=61 beamlets, or about 100 beamlets or more, and the plurality of beam spots 5.11 to 5.MN may have different grating configurations, such as hexagonal or circular gratings.

Each primary charged particle beamlet is scanned over the wafer surface 25 as shown in the example of a primary charged particle beamlet with beam spots 5.11 and 5.MN and scan paths 27.11 and 27.MN. For example, a scan of each of a plurality of primary charged particles is performed by moving back and forth along the scan path 27.11...27.MN, and the multi-beam scanning deflector system 110 causes each Focal points 5.11...5.MN move together along the x-direction starting from the starting position of the image subfield line, which in this example is e.g. the leftmost image point of image subfield 31.MN . Then, by converging and scanning the primary charged particle beamlets 3 to the correct position, each focal point 5.11...5. One moves in parallel to the line start position of the next line in each individual subfield 31.11...31.MN. The movement back to the line start of the next scan line is called flyback. A plurality of primary charged particle beamlets 3 follow in parallel scanning paths 27.11 to 27.MN, so as to simultaneously obtain a plurality of scanning images of each sub-field 31.11 to 31.MN. For image capture, as mentioned above, a plurality of secondary electrons are emitted at the focal points 5.11 to 5.MN, and a plurality of secondary electron beamlets 9 are generated. The plurality of small secondary electron beams 9 are collected by the objective lens 102 , pass through the first converging multi-beam raster scanner 110 , and are guided to the detection unit 200 for detection by the image sensor 207 . The sequential data streams of each of the plurality of secondary electron beamlets 9 are transformed synchronously with the scan paths 27.11...27.MN in the plurality of 2D data sets, thereby forming digital image data of each sub-field. Finally, the multiple digital images of the multiple image sub-fields are stitched together by the image stitching unit to form the digital image of the first image block 17.1. Each image subfield is configured to have a small overlap area with adjacent image subfields, as shown by the overlap area 39 of subfield 31.mn and subfield 31.m(n+1).

Next, the requirements or specifications of the wafer inspection task are explained. For high-throughput wafer inspection, the image acquisition time per image tile 17.1...k (including the time required for image post-processing) must be fast. On the other hand, strict image quality specifications such as image resolution, image accuracy and repeatability must be maintained. For example, image resolution requirements are typically 2 nm or below with high repeatability. Image accuracy is also called image fidelity, for example, the edge position of a part, usually the absolute position accuracy of a part will be determined with high absolute accuracy. Typically, the requirement for position accuracy is about 50% of the resolution requirement or even lower. For example, measurement tasks require absolute precision in the dimensions of semiconductor features, with accuracies below 1 nm, below 0.3 nm or even 0.1 nm. Therefore, the lateral position accuracy of each focal point 5 of the plurality of primary charged particle beamlets 3 must be less than 1 nm, for example less than 0.3 nm or even less than 0.1 nm. Under high image repeatability, it is understood that repeated image captures of the same area produce first and second repeated digital images, and the difference between the first and second repeated digital images is below a predetermined threshold. For example, the difference in image distortion between the first and second repeated digital images must be below 1 nm, such as 0.3 nm, or even preferably below 0.1 nm, and the difference in image contrast must be below 10%. In this way, similar image results can be obtained even by repeating imaging operations. This is important e.g. for image capture and comparison of similar semiconductor structures in different wafer dies, or for comparing acquired images with representative images obtained from CAD data or databases or image simulations of reference images .

One of the requirements or specifications for wafer inspection tasks is throughput. The measurement area per acquisition time is determined by the dwell time, resolution and number of beamlets. Typical examples of dwell times are between 20 ns and 80 ns. Thus, the pixel rate at the fast image sensor 207 is in the range between 12 Mhz and 50 MHz, and approximately 15 to 20 image tiles or frames per minute may be obtained. A typical example of throughput is about 0.045 sqmm/min (square millimeters per minute) in high resolution mode with a pixel size of 0.5 nm for 100 beamlets and a larger number of beamlets, e.g. 10000 beamlets beam and a dwell time of 25 ns, the flux may exceed 7 sqmm/min. However, in prior art systems, the requirement for digital image processing severely limits throughput, eg digital compensation of prior art scanning distortions is time consuming and therefore undesirable. In a specific embodiment of the invention, the requirements for image post-processing are reduced and the throughput of measurement tasks with high precision is increased. Embodiments of the present invention enable high throughput of wafer inspection tasks while maintaining imaging performance specifications well within the aforementioned requirements.

The imaging performance of the charged particle microscope 1 is limited by the design of the electrostatic or magnetic elements of the object irradiation unit 100 , as well as higher order aberrations and manufacturing tolerances of eg the primary multi-beamlet forming unit 305 . Imaging performance is limited by aberrations such as distortion of multiple charged particle beamlets, focusing aberrations, telecentricity and astigmatism. FIG. 3 illustrates by way of example typical static distortion aberrations of a plurality of primary charged particle beamlets 3 in the image plane 101 . The plurality of primary charged particle beamlets 3 are focused in the image plane to form a plurality of primary charged particle beam spots 5 (three listed) in a grating configuration, in this example a hexagonal grating. In an ideal system, with the converging multi-beam raster scanner 110 turned off, each beam spot 5 is formed at the center position 29.mn (see FIG. 2 ) relative to the image subfield 31.mn (index m is used for is the line number and n is the column number). However, in a practical system, the beam spots 5 are formed at slightly deviated positions that deviate from the ideal positions on the ideal grating, as shown by the static distortion vectors in Fig. 3 . For the illustrated example of the main beam spot 141 , the deviation from the ideal position on the hexagonal grating is described by the distortion vector 143 . Distortion vector Given a lateral difference [dx,dy] from the ideal position, the maximum absolute value of the distortion vector can be in the range of several nm, for example above 1 nm, 2 nm or even above 5 nm. Typically, the static distortion vector of a real system is measured and compensated by an array of static deflection elements, such as any active perforated plate configuration 306.2. Furthermore, drift or dynamic changes in static distortion are taken into account and compensated for as described in German Patent Application No. 102020206739.2 filed on May 28, 2020, which is hereby incorporated by reference. The control and compensation of the aberrations is achieved by means of a monitoring or detection system and a control loop capable of actuating the compensator, for example, multiple times during the image scan, thereby compensating for the aberrations of the multi-beam charged particle microscope 1 .

However, the imaging performance of a charged particle microscope is limited not only by design aberrations and drift aberrations of the electrostatic or magnetic elements of the object irradiation unit 100 , but also by the first converging multibeam raster 110 in particular. The deflection-scanning system and its properties for single-beam microscopy have been intensively studied. However, for multi-beam microscopy, conventional deflection scanning systems for scanning deflection of a plurality of charged particle beamlets exhibit inherent properties not disclosed in the prior art. The beam path through the deflection scanner in Figure 4 details the intrinsic properties in more detail.

Figure 4a illustrates the beam path of a single primary charged particle beam through a prior art scanning deflector 110 with deflection electrodes 153.1 and 153.2 and a voltage source. For simplicity, only the deflection scanner electrodes for raster scan deflection in the first direction are illustrated. During use, a scanning deflection voltage difference VSp(t) is applied and an electrostatic field is formed with equipotential lines 155 between electrodes 153.1 and 153.2. Axially charged particle beamlet 150a corresponding to image tile 31.c having image tile center 29.c coincident with optical axis 105 is deflected by an electrostatic field and follows true beam path 151f through deflector electrode 153.1 and 153.2 Intersecting bodies between 189. The beam trajectory can be approximated by first order beam paths 150a and 150f having a single virtual deflection at pivot point 159 . The charged particle beamlet traveling along path 150z is focused by objective lens 102 in object plane 101, as shown in the lower part of Fig. 4a. The subfield coordinates are given in relative coordinates (p,q) with respect to the center point 29.c of the subfield 31.c.

For maximum deflection to the maximum subfield point at coordinate _pf , apply a maximum voltage difference _VSpmax , and for deflection of incident beamlet 150a to a subfield point at distance _pz , apply an opposite voltage VSp, and The incident beamlet 150a is deflected by a deflection angle in the direction of the beam path 150z. The non-linearity of the deflector is compensated by determining the functional dependence of the deflection angle and the deflector voltage difference VSp. By calibration of the functional dependence VSp(sin(α)), a nearly ideal scanner for a single primary charged particle beamlet is achieved, with a single common pivot point 159 for deflected scanning of a single charged particle beamlet. Note that the lateral displacement (p, q) of the beam spot position in the image plane is proportional to the focal length f of the objective lens 102 multiplied by sin(α). For example, field points in the area, p _z = f sin(α _z ). For small angles α, the function sin(α) usually approximates α. As will be described in more detail below, while distortions induced by scanning with a single-beam microscope can be minimized, other scanning-induced aberrations such as astigmatism, defocus, hairline aberration, or spherical aberration vary with field size. Increases and decreases the resolution of charged particle microscopy. Furthermore, as the field size increases, the deviation from the virtual pivot point 159 becomes more and more significant.

In a multi-beam system, according to the functional correlation VSp(sin(α)), a plurality of small beamlets of charged particles are scanned in parallel using the same deflected scanning gas and the same voltage difference. In Fig. 4b, the intersection point 108 of the plurality of primary charged particle beamlets coincides with the virtual pivot point 159 of the axial primary beamlet 150a, and each charged particle beamlet passes through the electrostatic field at a different angle. Exemplifying a charged particle beamlet 157a with an incident angle β, the corresponding subfield 31.o has the center of the image subfield 29.o. The angle β is related to the distance X from the center coordinate 29.o to the optical axis 105 by sin() = X/f, and the focal length of the objective lens 102 is f. With the deflection scanner 110 off (VSp(t) = 0V), the beamlet traverses the path 157a and is focused by the objective lens 102 to the center point 29.o of the subfield 31.o. However, although the deflection scanner is approximately ideal for axial beamlets as shown in Fig. 4a, it is not ideal for field beamlets at angle of incidence β if a voltage difference is applied. Due to the finite thickness of the deflection field, the path lengths through the electrostatic field are different for each incident beamlet at different angles of incidence β, and the actual beam paths 157z and 157f deviate from the first-order ideal beam paths 163z and 163f. This is illustrated for the beam paths of the two subfield points with coordinates _pz and _pf , and the actual beam paths 157z and 157f. The angles of the actual beam paths 157z and 157f deviate from the angles of the ideal beam paths 163z and 163f, and each beam is virtually deflected at a different virtual pivot point 161z and 161f, offset from the beam intersection point 108. For example, if a voltage VSp(sin(α ₀ )) is applied, the primary charged particle beamlet 157a is deflected by an angle other than α ₀ , and follows beam path 157z with virtual deflection point 161z. Consequently, the charged particle beam spot is distorted by the local distortion vector dpz.

The deviation in the deflection angle increases as the angle of incidence increases, and so does the distortion caused by the scan produced by the converged multi-beam raster scanner 110 . In a first embodiment of the present invention, scanning-induced distortion is reduced by a modified design and operation of the converged multi-beam raster scanner 110 . In the second specific embodiment of the present invention, a first multi-beam scanning correction system 601 is provided to further reduce distortion caused by residual scanning.

Differences in deflection angles produce scan-induced distortion, and differences in the position of the virtual pivot point are responsible for scan-induced telecentric aberrations. FIG. 5 schematically illustrates the system 171 in front of the scanning converging multi-beam raster scanner 110 from which a plurality of primary charged particles are incident on the first converging multi-beam raster scanner 110 . The plurality of charged particle beamlets is shown by two beamlets comprising an on-axis charged particle beamlet 3.0 and an off-axis charged particle beamlet 3.1, which pass through the intersecting volume 189 of the raster scanner 110 and are focused by the objective lens 102 to form A plurality of focal points are shown by focal points 5.0 and 5.1 on the surface 25 of the wafer 7 . When the raster scanner 110 is in the off state and no voltage difference VSp is applied to the electrode 153, the beam spots 5.0 and 5.1 are located at the center points 29.0 and 29.1 of the respective image sub-fields. If the voltage difference VSp(sin(α ₀ )) has been applied, the beamlet 3.0 follows the ideal path 150 and is deflected to the strip field point Z ₀ . In the linear representation of Figure 5, the beamlet 3.0 appears to be deflected at the beam intersection point 108 corresponding to the virtual pivot point 159 of Figure 4a. The beamlet 3.0 therefore irradiates the wafer surface 25 at the same angle of incidence as the center position 29.0. The off-axis beamlet 3.1 has been deflected to the opposite ribbon field point _Z1 of the opposite image subfield. The off-axis beamlet 3 . 1 appears to be deflected along the representative beam path 157 at the virtual deflection point 161 , offset from the beam intersection 108 . Therefore, the deviation of the telecentric angle of the beamlet 3.1 at the scanning position with respect to the zonal field point _Z1 from the telecentric angle at the central field 29.1 corresponds, in addition to the aforementioned distortions, to the resulting distortion caused by the scanning of the beamlet 3.1. Telecentric aberration. In a third embodiment of the present invention, the second multi-beam scanning correction system 602 reduces the telecentric aberration caused by scanning.

The deviation of the focus position at the scan position of each of the plurality of charged particle beamlets 3 is described by the scan distortion vector field of each image sub-field 31.11 to 31.MN. Figure 6 illustrates scanning artifacts in an example image subfield 31.15 (see Figure 7). In this paper, the image subfield coordinates (p,q) relative to the respective centers of each image subfield 31.mn are used, while the scan distortion is described by the vector [dp,dq] for each individual image subfield 31. The function of the image subfield coordinates (p, q) of mn. The center position (p,q)=(0,0) of each image subfield is described by (x,y) coordinates relative to the optical axis 105 . Each image center coordinate can be distorted from a predetermined ideal raster configuration by a static offset (dx,dy) as a function of (x,y) coordinates, as shown in FIG. 3 . Static distortion is usually compensated by the static perforated plate 306.2 and is not considered in the scan distortion [dp,dq]. Since the scanning distortion in each image subfield 31.11…31.MN is different, the scanning distortion is generally described by the four-dimensional scanning distortion vector [dp,dq] = [dp,dq] (p,q;x _ij ,y _ij ) , with local image subfield coordinates (p,q) and discrete center coordinates (x _ij , y _ij ) of the image subfield.

Figure 6 shows the scanning distortion vector [dp,dq] on the image subfield 31.15. In this example, the maximum scan distortion is located at the maximum image subfield coordinate p = q = 6µm, with a scan distortion vector [dp,dq] = [2.7nm, -1.6nm]. The length of the largest scanning distortion vector in this image subfield is 3.5 nm. Typical maximum scan distortion aberrations in the imaging subfield are in the range of 1 nm to 4 nm, but may even exceed 5 nm.

Figure 7 illustrates the maximum scan distortion per image subfield 31.11 to 31.MN in a perfectly aligned conventional multibeam charged particle microscope paradigm with a plurality of J=61 primary charged particles in a hexagonal grating configuration small beam. The maximum scan distortion for each image subfield is indicated by the area of the circle. The maximum scanning distortion of the image sub-field 31.55 on the optical axis of the multi-beam charged particle microscope is small or almost zero. The maximum scan distortion increases with the distance of the image subfield from the optical axis, and the maximum of all maximum scan distortions is reached at the image subfield 31.15 or 31.91, and the distance to the optical axis is greatest, so relative to the optical axis 105 At beam intersection 108 there is a maximum propagation angle β. The area of the circle represents the maximum scan distortion for each subfield, and the diameter of the circle increases linearly with the distance from the center of the image subfield to the optical axis, as shown by line 197 . In one example, scan distortion has a dominant component that is linearly dependent on the subfield coordinates (p, q) and quadratic dependency on the image subfield center position (x, y).

In the example of FIG. 7, the converged multi-beam raster scanner 110 is configured to reduce the distortion caused by scanning at the axial beamlets of the central sub-field 31.55, and corresponds to the Distortion caused by a maximum scan of a subfield of a beamlet. In an example of the present invention, the scan deflection voltages VSp(t) and VSq(t) of the converged multi-beam raster scanner 110 are set to minimize the maximum scan The resulting distortion causes some scan-induced distortion for the axial beamlets of the central sub-field 31.55, but the maximum scan-induced distortion is reduced from eg 5 nm to below 3 nm.

In a first embodiment of the present invention, scanning imaging aberrations including scanning distortions of the multi-beam charged particle microscope 1 are reduced by an improved design of the converged multi-beam raster scanner 110 . The improved convergent multibeam raster scanner 110 according to the first embodiment minimizes scanning distortion by generating a laterally optimized electrostatic deflection field such that during operation, a single The beamlets are deflected by the corrected deflection angle α and are deflected approximately at a common virtual pivot point corresponding to the beam intersection point of the plurality of primary charged particle beamlets 3 . The improved convergent multibeam raster scanner 110 includes a set of deflection electrodes with an optimized deflection electrode physical design, and a set of correction electrodes for dynamically adjusting the electrostatic deflection field during the scanning deflection of a plurality of primary charged particle beamlets . In one example, the set of correction electrodes includes a correction electrode disposed between two deflection electrodes. In one example, the set of correction electrodes includes at least one correction electrode arranged upstream or downstream of at least one deflection electrode in the propagation direction of the primary charged particle beamlet. In a first embodiment, scanning imaging aberrations, including scanning distortions of a multi-beam charged particle microscope, are reduced by optimizing the multi-beam deflection scanner design, where the aberrations and charging of the deflection yoke 110 Additional scanning aberrations of the particle microscope (such as objective 102) are compensated.

Fig. 8a shows a first example of the first embodiment. A set of scanning deflection electrodes includes first deflection electrodes 181.1 and 181.2 for scanning and deflecting a plurality of primary charged particle beamlets in a first direction, and for scanning and deflecting a plurality of primary charged particle beamlets in a second direction The second deflection electrodes 183.1 and 183.2. For example, "DESIGN OF A NON-EQUISECTORED 20-ELECTRODE DEFLECTOR FOR E-BEAM LITHOGRAPHY USING A FIELD EMISSION ELECTRON BEAM" published by ER Weidlich in Microelectronic Engineering Vol. 11, p.347-350 (1990) , which describes the design of a set of deflection electrodes optimal for generating a uniform deflection field for a single electron beam system, which is hereby incorporated by reference. A plurality of primary charged particle beamlets are configured in a hexagonal grating configuration, and each beamlet has a different propagation angle (β _x , _βy ). The cross section of the intersecting body 189 of the plurality of primary charged particle beamlets is therefore approximately hexagonal in shape. To compensate for the rotation of the plurality of primary charged particle beamlets by the magnetic objective 102, the set of deflection electrodes 181 and 183 and the intersecting body 189 are rotated relative to the global xy coordinate system. The region of maximum scan distortion illustrated in FIG. 7 is indicated by arrow 191 . A modified deflection scanner design includes a set of deflection electrode configurations that deviate from the circular shape (dashed line). In one example, the deflection electrodes are arranged in an oval shape, and the distance between the deflection electrodes and the intersecting body 189 is closer in the direction of the maximum scanning distortion region indicated by the arrow 191 . In one example, the deflection electrodes have different azimuthal extensions. The deflection electrodes 183.1 and 183.2 for deflecting the scan in the second direction have a different azimuth spread ϕ3 compared to the deflection electrodes 181.1 and 181.2 for deflecting the scan in the first direction with the azimuth spread ϕ1.

Furthermore, a set of correction electrodes 185 comprising electrodes 185.1, 185.2, 185.3, 185.4 is arranged outside the intersecting body 189 and in sequence between the set of deflection electrodes. During use, a plurality of correction voltage differences VC (i=1...4, t) are applied to the correction electrodes, synchronized with the scanning voltage differences VSp(t) and VSq(t) of the set of deflection electrodes. During use, the correction electrode 185 produces a variable correction deflection field which is added to the deflection field produced by the set of deflection electrodes 181 and 183 . The set of correction electrodes is configured to generate, during use, a correction field which, during scanning, acts in particular on the beamlet with the largest angle of propagation in the corners of the hexagonal raster configuration. During scanning, the correction voltage difference VC (i=1...4,t) varies according to the scanning distortion, as shown in FIG. 6 . Thereby reducing scanning distortion during image scanning.

Fig. 8b illustrates a second example of the first embodiment, where a modified converged multi-beam raster scanner 110 is adapted to the symmetry of the grating configuration. In this example, the plurality of primary charged particle beamlets are arranged in a Cartesian or rectangular grating configuration with corresponding angles β _x , β _y , and the cross section of the intersecting volume 189 has an approximately rectangular form. As in FIG. 8a , the deflector system 110 of FIG. 8b is rotated relative to the global coordinate system (x,y) to pre-compensate the rotation by the objective lens 102 (see FIG. 1 ) arranged downstream of the converging multibeam raster scanner 110 . The set of deflection electrodes 181 and 183 for generating a deflection field for the scanning deflection of a plurality of primary charged particle beamlets is arranged in a rectangle, comprising deflection electrodes 181.11, 181.12, 181.21 for deflection or raster scanning in a first direction and 181.22, and deflection electrodes 183.11, 183.12, 183.21 and 183.22 for deflection or raster scanning in the second direction. The convergent multi-beam raster scanner 110 further comprises a first set of correction electrodes 185 comprising first correction electrodes 185.1 to 185.4 arranged near the beamlets with the largest propagation angle. The first set of correction electrodes 185 is configured to locally add a non-uniform correction field, which acts in particular on primary charged particle beamlets with distortions caused by large angles and thus large scans. Next, the converged multi-beam raster scanner 110 further includes a second set of correction electrodes 187.1 to 187.8, which are disposed between each pair of deflection electrodes 181 or 183 and the first correction electrode 185. With the second set of correction electrodes, an additional degree of freedom in correction field generation is provided, for example to control non-uniform correction field coverage produced by the first set of correction electrodes.

In this example, each deflection electrode for generating a deflection field during image scanning is configured as a pair of deflection electrodes, such as a first pair of deflection electrodes 181.11 and 181.12 and a second pair of deflection electrodes 181.21 and 181.22, for Scan deflection. A further degree of freedom is provided by configuring the deflection electrodes from a pair of two or a plurality of electrodes. For example, during image scanning in a first direction using deflection electrodes 181.11 to 181.22, a variable non-uniform scan deflection field can be produced which is uniform in the central region of intersecting volume 190 but for large propagation angles through region 189 The beamlets have a predetermined variable non-uniformity. In addition, during the image scanning of the deflection electrodes 183.11 to 183.22 in the second direction, the deflection electrodes 181.11 to 181.22 can generate a predetermined variable non-uniform scan correction field in the direction of the first scan direction, which is different from the scan deflection in the second direction. synchronization and, for example, scan distortion in the form of image rotation for beamlets with larger propagation angles can be compensated. Furthermore, by means of a further degree of freedom, for example manufacturing tolerances of a true convergent multibeam raster scanner 110 can be compensated.

Fig. 9 illustrates an aspect of the improved deflection scanner according to Fig. 8b, wherein the performance of the deflection scanner is optimized by an improved selection of the voltage difference between the deflection electrodes of the converging multibeam raster scanner 110. In one example, the deflection electrodes 181 for deflecting the scan in the first direction include a first pair of deflection electrodes 181.11 and 181.12 and a second pair of deflection electrodes 181.21 and 181.22. In Fig. 9a the required voltage difference is illustrated as a function of the deflection angle VSp(sin[alpha]) for a deflection scanner with a single deflection electrode. The graph illustrates the voltage difference 175 required to be applied to two individual deflection electrodes 181.1 and 181.2 to deflect scanning in a first direction. The non-linear effect as previously described is compensated by the deviation of the voltage difference 175 from the linear line 173 . The corrected voltage difference for two pairs of deflection electrodes is illustrated in Fig. 9b. During use, a first voltage difference 177.1 is applied to opposing electrodes 181.11 and 181.21 of opposite sign respectively, and a second voltage difference 177.2 is applied to opposing electrodes 181.12 and 181.22 of opposite sign respectively. The average voltage difference applied to the pair of electrodes is the same as voltage difference 175 . Axial beamlets and beamlets near the optical axis transmit the inner region 190 in Figure 8b. In this region, the electrostatic field difference generated by the voltage difference 177.1 and 177.2 has little effect. The remaining rotation can be compensated by applying variable offset voltages 179.1 and 179.2 (not shown to scale) to the pair of electrodes 183.11 to 183.22 to scan in the second direction. Consequently, the beamlets in the outer regions of the transmissive region 189 experience a slightly non-uniform deflection field. Therefore, distortion caused by scanning can be reduced.

FIG. 10 illustrates another example of the first embodiment. In this example, the set of correction electrodes comprises electrodes arranged upstream or downstream of the deflection electrodes in the direction of propagation of the plurality of primary charged particle beamlets 3 . The first and second deflection electrodes 181.11, 181.12 are opposite the first and second deflection electrodes 181.31, 181.32 and are configured for deflection scanning in a first direction X'. Due to the divergence of the plurality of primary charged particle beamlets, the plurality of beamlet transmission intersections 189 form a beam tube comprising z-sections 189.1 to 189.3 of different lateral extension. In an example, a set of first correction electrodes 195.1 to 195.4 is provided and arranged to add a correction field during the scanning deflection of the plurality of primary charged particle beamlets. The correction electrodes are arranged upstream and downstream of the deflection electrode 181 in the direction of propagation of the primary charged particle beamlet, in FIG. 10 it is the z direction. At these z positions, primary beamlets with larger propagation angles, such as beamlets 3.1 and 3.2, have a greater distance to the optical axis 105 and the influence of the non-uniform correction field produced by the correction electrode varies with the beamlet The propagation angle increases with increasing. The additional second set of correction electrodes 193.1 to 193.4 provides an additional degree of freedom to optimize this modified non-uniform scanning deflection field in the intersecting volume 189. The correction electrodes 193 or 195 are illustrated in cross-section in FIG. 10 and arranged in segments along the circumference of the primary beamlets for locally influencing the plurality of charged particle beamlets, similar to the correction electrodes illustrated in FIG. 8 . During use, a variable correction voltage difference is applied to the correction electrodes, and during deflection scanning, a time-varying non-uniform correction field is synchronously added to the scanning deflection field. For example, in the deflection field, the primary charged particle beamlet 3.1 is deflected to the right and propagates along the path 3.1f, and transmits the correction field generated by the correction electrodes 193.2 and 195.2, while the primary charged particle beamlet following the path 3.2f 3.2 is further away from the electrodes 193.2 and 195.2 and does not experience a non-uniform correction field. Thereby, variations of different local scan distortions in different image sub-fields can be corrected.

FIG. 11 illustrates another aspect of an improved deflection scanning system 110 . The length Z1 of the deflection electrodes 181.1 and 181.2 for scanning deflection along the first direction and the length Z1 between the deflection electrodes 183.1 and 183.2 for scanning deflection along the second direction are adjusted along the z-direction by adjusting the length or longitudinal extension of the deflection electrodes. The length Z3 reduces the increased scan distortion in the four corners, as shown by arrow 191 in Figure 8a.

Through the modified design of the deflection electrodes, a predetermined non-uniform electrostatic field is provided within the intersecting volume 189 of the converging multi-beam raster scanner 110 . Predetermined non-uniform electrostatic field varying with time, thereby enabling deflected scanning of multiple primary charged particle beamlets, thereby minimizing scanning-induced aberrations, such as transmission intersecting volumes with increasing angle to the optical axis Distortion caused by scanning of beamlets. In a first example, the deflection electrodes are configured to produce a predetermined non-uniform electrostatic scanning deflection field, wherein the non-uniformity of primary beamlet transmission intersection volume 189 increases with increasing angle β. In a second example, additional correction electrodes are provided for creating a variable increasing non-uniformity in primary beamlet transmission intersection volume 189 with increasing scan deflection angle a during image scanning. During the design and simulation of the multibeam charged particle microscope 1, the shape and position of the scanning electrodes and the shape and position of the correction electrodes are optimized. In one example, additional aberrations of other elements of the optical system are considered. Calculate the theoretical voltage differences VS(t) and VC(t) required to generate the scanning deflection field and the scanning correction field, and store the control signal for generating the scanning correction voltage difference VC(t) in the multi-beam charged particle microscope 1 In the memory of the control unit 800. During the adjustment and calibration of the multi-beam charged particle microscope 1, the voltage differences VS(t) and VC(t) required for scanning the deflection and correction fields are adjusted and calibrated, and the calibrated voltage difference VS(t) and used to generate The control signal of the scanning correction voltage difference VC(t) is stored in the memory of the control unit 800 of the multi-beam charged particle microscope 1 . During image scanning, calibration voltage differences VS(t) and VC(t) are generated. An example of generating the correction voltage difference VC(t) synchronously with the scanning voltage difference VS(t) is described below. In one example, the inhomogeneity of the scan deflection field is generated along the first or second scan direction with a parabolic or higher order shaped correction field. In an example, the inhomogeneity of the deflection field is produced by a correction field which has a saddle point shape on the optical axis and exhibits parabolic or higher order inhomogeneities of opposite signs in the first and second directions.

FIG. 21 illustrates another example of a converged raster scanner 110 with a predetermined non-uniform field distribution. In this example, additional electrodes 153.1a, 153.1c and 153.2a, 153.2c are provided which form an angle with the optical axis of the charged particle microscope. Thereby, on the charged particle beamlet entry side and exit side of the intersection body 189, the inclination angle of the electric field is controlled. Using the correction electrode that forms an inclination angle with the optical axis, the scanning deflection field effect of a plurality of small beams with different incident angles can be optimized, including small beams 3.0 parallel to the optical axis and those with the largest angle β2 with the optical axis Beamlet 3.1.

According to a second embodiment of the invention, the multi-beam charged particle microscope 1 comprises a multi-beam scan correction system, such as a scan distortion compensator array 601, configured to compensate for residual scan-induced distortion (see Figure 1). With the scan distortion compensator array 601 in the path of the primary charged particle beamlet, each individual primary charged particle beamlet is individually affected and deflected by scanning of each primary beamlet, for each individual image subfield , compensating for the scan distortion caused by the long-stroke convergent multi-beam raster scanner 110 by a few nm. The scan distortion compensator array 601 is illustrated in FIGS. 12-15 . The short-stroke scanning distortion compensator array 601 is configured as an aperture array 620 and includes apertures arranged in a raster configuration of primary charged particle beamlets 3 , in this example a hexagonal raster configuration. FIG. 12 illustrates an aspect of the porous array 620 . Three of these holes are identified with reference numbers 685.1 to 685.3. On the circumference of each of the plurality of holes, a plurality of electrodes 681.1 - 681.8 are arranged, in this example, the number of electrodes per hole 685 is eight, but other numbers, such as four or more, are also possible. The electrodes 681 are electrically insulated with respect to each other and with respect to the carrier of the porous array 620 . Each electrode is electrically connected to a fast array scanning control module through conductive lines 607 .

Although the design of the static porous array 620 is known in principle for static compensation of static distortions as described in FIG. 3 , scan correction or compensation of scan-induced aberrations is not possible using known methods. For scan correction synchronized with the scan operation, each beamlet has at least two highly dynamic scan correction voltage differences, e.g. eight scan correction voltage differences are generated and fed into J primary beamlets at full scan speed into vacuum bundle each one. Each primary charged particle beamlet passing through one of the apertures 685 undergoes scan deflection by applying a series of predetermined scan voltage differences VCA(t) to each of the electrodes 681 synchronized with the image raster scan, Synchronized with scanning deflection through the long-stroke convergent multi-beam raster scanner 110 . Thus, scan distortion in the image subfield compensates for the amount of distortion caused by, for example, residual scans of up to 3 nm by deflection in opposite directions of the individual beamlets corresponding to the image subfield. Since only electrostatic effects are concerned, the charged particle beamlets transmitted through the opposing aperture 685 can be individually adjusted or changed at high speed synchronously with the long run raster scan.

Further details are illustrated in the example of hole 685.3. Here a first set of electrodes 687.1 and 687.2 is provided for deflection scanning of a beamlet of charged particles through aperture 685.3 in the first or p direction. Here a second set of electrodes 688.1 and 688.2 is provided for deflection scanning of a charged particle beamlet through aperture 685.3 in the second or q direction. Additional electrodes may be provided here for further manipulation of the charged particle beamlets through the aperture 685.3, these electrodes being used to correct for astigmatism.

The plurality of scanning correction voltage differences VCA(t) applied to the first and second sets of deflection electrodes, and the raster scanning voltage difference VSp supplied to the converged multi-beam raster scanner 110 at a signal frequency of about 20 MHz to 50 MHz (t) and VSq(t) are provided synchronously. FIG. 13 illustrates the configuration of the scanning distortion compensator array 601 according to the second embodiment of the present invention, which can deflect and scan a plurality of J=M×N primary charged particle beamlets, wherein the number of charged particle beamlets is J More than 10 beamlets, preferably about J = 61 beamlets or more, for example J > 100 beamlets or even J > 1000 beamlets. Considering that each beamlet has at least 4 deflection electrodes, the number of driving signals or voltage differences VCA (i=1...4J,t) for J beamlet deflection scanning is at least 4J, and the 4J signal or voltage difference VCA(i = 1...4J,t) each provide a signal frequency of about 20 MHz to 50 MHz or even higher, based on a dwell time of about 25 ns at each pixel. Consequently, data rates typically exceed 10 Gbit/s. Figures 13 and 14 illustrate an example of achieving such a high data rate in the example of static voltage switching arrays 611 and 612 applied to aggregate scan voltages VSp(t) and VSq(t). The scan distortion compensator array 601 includes a perforated plate 620 with a plurality of holes 685 , deflection electrodes as shown in FIG. 12 , and a scan array control unit 622 . Each electrode for deflection scanning in the first direction is connected to the output of the first electrostatic voltage conversion array or unit 611 through a conductive line 607.1 and a first plurality of conductive lines 613. The first static voltage conversion array 611 is controlled by the first static control signal 615 provided by the operation control memory 626 of the scan array control unit 622 . A first scan deflection voltage difference VCAP(t) for parallel scan deflection of each of the plurality of primary charged particle beamlets in a first direction is provided by a scan voltage generator (not shown) via a first power supply line 609 . The first scan deflection voltage difference VCAP(t) is proportional to the aggregate scan voltage VSp(t) generated by the convergent multi-beam scan deflector 110 for deflecting the scan. The first direction is the direction of subfield coordinate p, which is parallel to the x direction in the image plane. The scan array control unit 622 includes a memory 626 for storing the first plurality of control signals 615, including static control signals for each set of deflection electrodes for scanning correction in the first direction, such as electrodes 687.1 and 687.2 of FIG. 12 . The first electrostatic voltage conversion array 611 generates a plurality of appropriate voltage differences VCAP(u=1...2J,t) to the group of u deflection electrodes for synchronizing with the first scanning deflection voltage difference VCAP(t) in the first direction Scanning deflection of each charged particle beamlet. Each voltage difference applied to the deflection electrodes for deflection in the first direction, such as electrodes 687.1 and 687.2, is proportional to the scan deflection voltage difference VCAP(t), and thus to the aggregated scan voltage difference VSp(t).

A second set of static control signals 616 is provided to the second static voltage conversion array 612, which is connected to each of the v second electrodes for deflection scanning in the second direction via conductive lines 614 and wiring 607.2, for example comprising holes Electrodes 688.1 and 688.2 of 685.3 are shown in FIG. 12 . The second static voltage conversion array 612 generates a plurality of second voltage differences VCAq (v=1...2J, t) for each of the v deflection electrodes for deflecting from the second scan provided via the second power supply line 610 The voltage difference VCAq(t) reduces the scanning deflection of the beamlets in the second direction (here the direction of the subfield coordinate q, parallel to the y direction in the image plane). Each voltage difference applied to each deflection electrode for deflection in the second direction, such as electrodes 688.1 and 688.2, is proportional to the scan deflection voltage difference VCAq(t), and thus to the aggregated scan voltage difference VSq(t).

As shown in FIG. 6 , the scanning distortion vector [dp,dq] in the image subfield usually has scanning distortion vector components in the first direction (here, the p coordinate) and the second direction (here, the q coordinate). Therefore, in the example of FIG. 13, the first and second voltage converting units 611, 612 are connected by a signal line 618, and, in addition to the foregoing, generate A plurality of voltage differences VCp(v,t) for scanning deflection in two directions is provided to a plurality of electrodes for scanning in a second direction, and vice versa for VCAq(u,t). Thereby, the residual scanning distortion vector components in the first direction dp(p,q) and the second direction dq(p,q) are related to the aggregated scanning signals VSp(t) and VSp (t) Synchronous Compensation. Since the scan distortion amplitude ||dp;dq|| is small, e.g. below 3 nm, or below 1.5 nm, the voltage difference required to individually compensate for the scan-induced distortion of each of the plurality of charged particle beamlets is very small. Low, such as below 100 mV, below 10 mV or even lower.

An example of a static voltage conversion array or unit 611 or 612 is given by a programmable resistor array, which generates multiple output voltages proportional to a variable input voltage. FIG. 14 illustrates an example of a static voltage conversion array 611 . In this example, the static voltage conversion array 611 is configured as a programmable resistor array for reducing the variable drive voltages VCAp(t) and VCAq(t) individually to a plurality of voltage differences VCAp(u,t) and VCAp(v , t) for individual compensation of the distortion (dp,dq) induced by the scanning of each of the plurality of charged particle beamlets. The static voltage conversion array 611 provides at least two voltage difference components to each of the u=1...2J correction deflection electrodes, including a first voltage difference VCAp(u,t) synchronized with the drive voltage VCap(t) and a first voltage difference VCAp(u,t) synchronized with the drive voltage VCap(t) The second voltage difference VCAq(u,t) of the driving voltage VCAq(t). The first and second driving voltages VCAp(u, t) and VCAq(u, t) are added by the voltage adder 641.u and provided to the opposite uth electrode, such as the electrode 687.1, for compensating Distortion caused by a single scan of a small beamlet. For each of j = 1...4J deflection electrodes, a first series of resistances 633.j of increasing impedance, for example a series of resistances of 1 Ω, 2 Ω, 4 Ω, 8 Ω are connected in series and in parallel with each resistor and configure a Sequence Transistor 639.n. For example, for the deflection electrode 687.1, a first series of resistors 633.11 to 633.14 are arranged in parallel with a first series of transistors 639.11 to 639.14 to reduce the driving voltage VCAp(t) provided at the power line 609, thereby reducing the voltage by Controlled by a plurality of static control signals 635.11 to 635.14 provided to the first sequence of transistors 639.11 to 639.14. By switching eg a transistor 639.13 from an off state to an on state by a control signal 635.13 supplied to the gate of the resistor 639.13, the opposite resistor 633.13 is bridged and the voltage is not dropped by the resistor 633.13. If the transistors 639.11 to 639.14 are in the off state, the driving voltage, eg, the scanning deflection voltage difference VCap(t), is lowered by the opposing resistors 633.11 to 633.14. If all transistors are switched to the off state, the drive voltage difference VCAp(t) is reduced to a minimum and a minimum deflection of the relatively small beam is achieved. If all transistors are switched to the conducting state, the full scan deflection voltage difference VCAp(t) is supplied to the opposite electrode and achieves maximum deflection of the relatively small beam. In this way, scanning distortion maxima of, for example, beamlets of approximately up to 5 nm are compensated. After 4 resistors are connected in series, the driving voltage difference VCAp(t) can be reduced to 16 different voltage levels between the maximum and minimum voltage difference, thereby reducing the maximum residual distortion of about 5 nm to about 0.3 nm.

The scanning deflection voltage difference VCAp(t) is directed to the plurality of electrodes of the porous array 620 in a predetermined manner by a sequence of static control signals 635 provided to the transistor 639 for switching the transistor and maintaining the transistor in an on or off state. Each of them decreases. The output voltage VCAp(u,t) 613.1 supplied to a particular uth electrode (such as electrode 687.1 of FIG. The scan deflection voltage difference VSp(t) is proportional to a long stroke raster scan of a charged particle beamlet in the first or p direction.

In one example, the scan correction in a first direction (eg, p-direction) depends on the scan position in a second direction (eg, q-direction). Therefore, the static voltage conversion array 611 further includes a voltage combiner 641.1 connected to a programmable resistor array including a resistor 633.3 driven by the second scanning deflection voltage difference VCAq(t) provided by the power supply line 610. Using a set of drive signals 637.11 to 637.14, a second correction voltage component VCAq(u,t) synchronized with the drive voltage VCAq(t) is generated to be proportional to the second scanning deflection voltage difference VCAq(t), and added to the first The correction voltage component is proportional to and synchronized with the second scan deflection voltage difference VSq(t) for long run raster scanning in the second or q direction.

In one example, the scan correction in the second direction (eg, q-direction) depends on the scan position in the first direction (eg, p-direction). Thus, the static voltage switching array 611 includes an array of other programmable resistors driven by the first scanning deflection voltage difference VCAp(t) provided by the power supply line 609 . Using a set of drive signals (not shown), a second correction voltage component VCAp(v,t) is generated in proportion to the first scanning deflection voltage difference VSp(t), which is synchronized with the drive voltage VCAp(t), but for The scan distortion vector component dq(p,q) in the second or q direction is compensated, proportional to the scan position in the first direction.

The number L of resistors, transistors and static control signals for reducing the scan deflection voltage difference to a predetermined voltage difference to compensate for scan induced distortion is illustrated as L=4, but the number L can be larger. The voltage combiner 641 may also be connected to an additional voltage difference signal, for example to provide an individual predetermined voltage offset to each aperture 685 to compensate for the static distortion offset, as shown in FIG. 3 . A programmable resistor array is an example of a quasi-static voltage converter by which large data rates can be generated and provided to the 4J electrodes of the scan distortion compensator array 601 . Equivalent implementations are also possible, such as an array of programmable source follower transistors that limits the drive voltage difference of each source follower transistor to that at the opposite gate of each source follower transistor. Provides a static signal proportional to the amount.

A plurality of static control signals comprising control signals 635.11 to 635.14 and control signals 637.11 to 637.14 are determined during the calibration step and stored in the memory 626 of the scanning array control unit 622 for scanning at least 4J of the distortion compensator array 601 each of the electrodes. The static control signals stored in memory 626 may be modified during operation of the multi-beam charged particle microscope, eg, between image acquisitions of a first image tile and a second image tile. Accordingly, the scan array control unit 622 is connected to the operation control unit 800 through the data connection 631 (see FIG. 13). In one example, scan array control unit 622 is connected to clock line 624 to synchronize the operation of scan distortion compensator array 601 with convergent multibeam raster scanner 110 . During image acquisition of an image tile, a plurality of static control signals 615 and 616 are constant and correct for scanning distortion in each image subfield by providing a plurality of 4J voltage differences to the 4J deflection electrodes, thereby Each 4J voltage difference includes first and second components proportional to the first and second scanning deflection voltage differences VCAp(t) and VCAq(t), which are provided to the long stroke convergent multibeam raster 110 The scanning deflection voltage differences VSp(t) and VSq(t) of the deflection scanner electrodes are synchronized. Thus, according to the second embodiment, the scan distortion produced by the convergent multibeam raster scanner 110 in combination with an additional optical element such as the objective lens 102 is compensated by the scan distortion compensator array 601 .

In one example, the number J of primary charged particle beamlets in the grating configuration is J=100. At least 4 electrodes with correction voltage differences are required to correct the distortion [dp,dq] caused by the scanning of each beamlet, so the programmable resistor array generates 4J=400 correction voltage differences and provides them to the plurality of electrodes. For each electrode, the voltage difference is the superposition of two components, the first component is linearly related to the first scan direction, the second component is linearly related to the second scan direction, 4J = 400 electrodes produce 8J = 800 voltage difference components required 8J = 800 programmable resistor sequences. For example, by sequentially using 4 resistors and four control signals for generating each voltage differential component, a reduction in residual scanning distortion of more than 10 times, eg up to 16 times, is achieved. A plurality of 32J = 3200 static control signals can be predetermined and provided by the memory of the operation control unit 622 .

A further reduction can be implemented by sequentially providing more than four programmable resistors, eg 8 resistors, whereby over 100 times reduction in scanning induced distortion can be achieved, eg up to 256 times. Accordingly, scanning distortion is reduced by at least a factor of 10, preferably by a factor of more than 100.

Typical first and second scanning deflection voltages VSp(t) and VSq(t) are used for scanning deflection of beamlets in first and second directions, as shown in FIG. 15 . For scanning deflection in the first direction (the p-coordinate in each subfield, parallel to the x-coordinate) using the converging multibeam raster scanner 110, a series of rapid voltage ramps VSp(t) are generated that deviate from the linear ramps by Compensate for non-linear effects of deflection scanners, as described above. After the time interval tl(n) of the nth row, the scan deflection voltage VSq(t) for deflection in the second direction (here the q direction on the wafer level, parallel to the y coordinate) is changed to deflect the next row Beamlet numbered (n+1), and the scan deflection voltage VSp(t) is set back to VSp _min . With the next voltage ramp during the time interval tl(n+1), the beamlet deflects the scan in row (n+1) until the end of the row is reached with VSp _max . The time interval tb is the aforementioned flyback interval. The two voltages are generated and supplied in a stepwise manner, e.g. the first voltage ramp VSp(t) consists of a series of constant voltages which are constant during the dwell time td of each pixel until the voltage VSp(t) changes to the deflection voltage , used to deflect the beam to the next pixel (see Zoom in for details).

It should be mentioned that in a system with a scanning wafer stage, the plurality of charged particle beamlets are deflected only in a first direction scan, while the position of the beamlets in a second direction is constant. In this example, VSq(t) is constant.

The voltage differences VSp(t), VSq(t) shown in FIG. 15 are the voltage differences VSp(t) and VSq( t) representative. The voltage differences VSp(t), VSq(t) also represent driving voltages VCAp(t) and VCAq(t), such as the power supply lines 609 and 610 supplied to the aforementioned scan distortion compensator array 601 . However, the maximum and minimum voltage differences VCAp _min , VCAp _max and VCAq _min , VCAq _max differ by at least two orders of magnitude. The maximum scan voltage difference of the long-stroke convergent multi-beam raster scanner 110 is typically about VSp _max =10 V or more, depending on the number of primary charged particles J . From the maximum scanning distortion, a maximum driving voltage difference VCAP _max for compensating for scanning distortion can be determined, for example for compensating for a maximum scanning distortion approximately below 5 nm, such as 2 nm or 1.5 nm. Thus, for scanning the distortion compensator array 601, the maximum voltage VCap _max according to the voltage ramp in FIG. 15 is typically in the range of 10 mV to 100 mV, eg about 50 mV.

Generally, for a symmetrical scanning system, the minimum value of the scanning voltage difference is symmetrical to the maximum scanning voltage difference. Especially for the linear part of the sweep distortion, the minimum voltage difference is given by VCApmin = -VCApmax, VCAqmin = -VCAqmax. Manufacturing errors or thermal drift of a multi-beam charged particle microscope can cause additional static distortion offsets for each of the plurality of primary charged particle beamlets, and can be compensated for by the static distortion compensator 306 as previously described.

In one example, the drive voltages VCAp(t) and VCAq(t) provided to the scan distortion compensator array 601 may be driven by the same scan voltage generator used for the converged multi-beam raster scanner 110, and the scan voltage difference VSp (t) and VSq(t) are generated synchronously, or are reduced from the scanning voltage difference VSp(t) and VSq(t) to the required maximum voltages VCAp _max and VCAq _max through a resistor. Thus, the scan distortion correction provided by the scan distortion compensator array 601 with a programmable resistor array is directly linked to the scan deflection produced by the convergent multibeam raster scanner 110 .

Fig. 15 is a simplified representation, only illustrating the scanning voltage differences VSp(t), VSq(t) of four lines, but the number of scanning lines is more, for example M = 5000 or more.

A similar implementation of the voltage conversion unit 611 or 612 for providing a plurality of correction voltage differences VCp(t) and VCq(t) proportional to the first and second scanning correction voltage differences VSp(t) and VSq(t), It can also be used for the control of the set of correction electrodes of the convergent multibeam raster scanner 110 according to the first embodiment, for example for the control of the set of correction electrodes 185.1 to 185.4, 187.1 to 187.4 or 195.1 to 195.4. Thus, a plurality of correction voltage differences are supplied to the correction electrodes synchronized with the drive voltage differences VSp(t) and VSq(t) for deflection scanning of the deflection electrodes.

In one example, other scan-induced aberrations, such as scan-induced astigmatism or focal plane variation, are additionally compensated for using the scan distortion compensator array 601 . Dynamic scan distortion is usually related to dynamic spot shape aberrations that occur in perturbed and unperturbed systems. In one example, a scanning astigmatizer array similar to a scanning distortion compensator array is provided, and the corrected voltage difference for each astigmatizer electrode is generated by a programmable resistor array or network as previously described. A plurality of, eg, two or three, such perforated plates are arranged in sequence, with opposing electrodes for compensating for aberrations such as astigmatism and defocus. A plurality of correction voltages are similarly provided according to the driving voltage differences VSp(t), VSq(t). For example, two voltage differences VCCp(t) and VCCq(t) are required for astigmatism correction. Likewise, the telecentric aberration scan compensator array 620 can be configured and operated as will be described in more detail below.

Some examples of aspects of the scanning distortion compensator array 601 are shown in FIG. 1 . In one example, the scanning distortion compensator array 601 is arranged in the propagation direction of the plurality of primary charged particle beamlets after the primary multi-beamlet forming unit 305, for example, between the primary multi-beamlet forming unit 305 and the first field between lenses 307 . In an example, the scan distortion compensator array 601 is configured as an additional element of the active multi-well plate configuration 306.1 or 306.2, eg by which static aberrations such as the static distortion offset shown in FIG. 3 are compensated. In another example, the scan distortion compensator array 601 is an element of the multi-pass beamlet forming unit 305 . As previously mentioned, the scan distortion compensator array 601 can also be configured to compensate for static distortion offsets, as shown in FIG. 3 . Using the scanning distortion compensator array 601, during image or raster scanning, the position of each charged particle beamlet focal point 311 in the intermediate image plane 321 is changed synchronously with the long-run raster scan, and the direction is the same as that obtained by using a converging multi-beam grating. The converging raster scanning of the plurality of primary charged particle beamlets by the scanner 110 results in the inverse of the distortion induced by this scanning.

In a third embodiment, the multi-beam charged particle microscope includes a second multi-beam scan correction system, such as a scan compensator array for compensating scan telecentricity errors as described above. A scanning compensator array 602 for compensating scanning telecentricity errors is arranged near the intermediate image surface 321 . The scanning compensator array 602 for compensating the scanning telecentricity error is configured similarly to the scanning distortion compensator array 601 and has a plurality of control signals for compensating the scanning induced telecentricity error. In addition to the static compensator 390 for compensating the static telecentric error, a scanning compensator array 602 for compensating the scanning telecentric error can also be configured, or it can be configured to additionally provide a plurality of deflection voltages for compensating the static deflection of the telecentric error . Utilize the scanning compensator array 602 for compensating the scanning telecentric error, by adjusting the individual propagation angle of each beamlet near the intermediate image plane 311 to compensate the telecentric error caused by scanning, so that during image scanning, the plurality of primary charged particles are small Each of the beams impinges on the wafer surface 25 at an angle of 90° with a deviation of less than 3 mrad or even lower.

其中根據下式的複數符號

，

掃描失真中a + b = 1的最低階或線性部分描述為

並且可寫成

According to a fourth embodiment, a multi-beam charged particle microscope with reduced scanning distortion and a method of operating a multi-beam charged particle microscope with reduced scanning distortion are provided. In order to optimize and adjust the deflection scanner, and to derive a plurality of control signals such as the scan distortion compensator array 601, the scan distortion [dp,dq] of each image subfield as shown in Fig. 6a is expanded into an enhanced sequence Coordinates (p,q) of the image subfield of :

where the plural notation according to

,

The lowest order or linear part of a + b = 1 in sweep distortion is described as

and can be written as

，

，

。 where the mixing angle μ, the orthogonality deviation ω and the rotation angle ρ. Thus, one way to describe the four linear scan distortions is given by the four linear distortion aberration scales M, squareness SQ, orthogonality OR, and rotation ROT, where

,

,

.

High-order distortion is, for example, third-order distortion such as pincushion distortion. Usually, the linear distortion aberration of each sub-field accounts for more than 80% of the distortion caused by the total scan. With the scan distortion compensator array 601 according to the second specific embodiment, linear scan distortion can be compensated by supplying a plurality of voltage differences to the deflection electrodes, which are proportional to the scan voltage differences VSp(t) and VSq(t) , which is proportional to the scan position (p,q) within each image subfield. The linear part of the scan distortion is described by four normalized linear distortion aberration vectors M, SQ, OR and ROT, each image subfield having raster coordinates (n,m). The linear part of the scan distortion (dp,dq) is thus compensated.

In one example, the linear parts M, SQ, OR and ROT are described by four normalization vectors SDV(i), where SDV(1) represents M, SDV(2) represents SQ, SDV(3) represents OR and SDV( 4) Representing ROT, the linear part of the scan distortion is described by the complex amplitude A(i;n,m) of the normalized scan distortion vector: [dp,dq](p,q;n,m) =

來實現正常化。然後比例因子E為乘法因子，代表掃描所引起的失真的最大強度[dp,dq](p,q;n,m)。 In one example, by setting the maximum value of each linear distortion vector SDV(i) to 1 nm, and by setting the maximum amplitude sum of all subfields with index (n,m)

to achieve normalization. The scale factor E is then a multiplicative factor representing the maximum intensity [dp,dq](p,q;n,m) of the distortion induced by the scan.

Figure 16 illustrates a method of operating a multi-beam charged particle microscope with reduced scanning distortion. In a first step S1 of the method of operating the multi-beam charged particle microscope 1 with reduced scanning distortion, the linear part of the residual scanning distortion is determined. This determination is achieved, for example, by a calibration measurement of the scan distortion at the calibration sample. A calibration sample may include a plurality of calibration structures at calibration locations and is disposed on the wafer stage. In one example, the calibration comprises a plurality of repeating patterns in a grating configuration similar to that of a plurality of charged particle beamlets, and the scanning distortion calibration measurement is repeated, wherein the relative displacement of the calibration pattern corresponds to the first The length of at least one image subfield between the second measurement. A difference between the first and second measurements can be derived, and a relative difference between image subfields corresponding to scan distortion can be determined. Analyze the measured scan distortion and calculate the linear part M(nm), SQ(nm ), OR(nm) and ROT(nm). A maximum scan distortion vector is determined, a scaling factor E is determined, and a complex number of amplitudes A(i;n,m) is determined.

In step S2, the maximum values of the correction voltage differences VCApmax, VCAqmax required for scanning the distortion compensator array 601 are determined according to the scaling factor E, and the first and second reduction factors F1 and F2 are determined. Determining the reduction factors F1 and F2 to realize the correction for the scanning correction of the plurality of primary charged particle beamlets according to the scanning voltage difference VSp(t), VSq(t) supplied to the converging multi-beam raster scanning gas 110 Voltage difference VCAp(t), VCAq(t).

In step S3, according to the correlation between the complex amplitudes A(i;n,m) of the linear distortion vector SDV(i) and the coordinates (n,m) of the image sub-field, the parameters used to control the programmable resistor array 611 and A plurality of control signals 635 and 637 of 612 (see reference numerals in FIGS. 12-14 ). For each of the deflection electrodes 687, 688 of each of the plurality of apertures 685 of the scanning distortion compensator array 601, for each image subfield of each beamlet or coordinate (n,m), respectively, A plurality of (at least 8) control signals 635 and 637 for controlling the programmable resistor arrays 611 and 612 are derived from the plurality of amplitudes A(i;n,m), and stored in the memory of the operation control unit 622 . The control signal comes from the required compensation of scanning-induced distortion in the image subfield at coordinates (n,m). Scaling the amplitude A(i; n,m) to the maximum distortion 1 in arbitrary units, the linear vector components correspond to the matrix elements, and the relative control parameters of the programmable resistor array can be calculated by matrix multiplication, and in bits according to the number of series resistors The length is converted to binary digits.

In step S4, a plurality of control signals 635 and 637 are provided to the programmable resistor arrays 611 and 612 during image scanning. The scan voltage differences VSp(t) and VSq(t) are reduced by reduction factors F1 and F2, and the reduced correction voltage differences VCAP(t), VCAq(t) are provided to the power supply line 609 of the programmable resistor array 611 and 610. Thereby, during image scanning, the plurality of primary charged particle beamlets are deflected and scanned by the convergent raster scanner 110 , and the linear part of the residual scan distortion is compensated by the scan distortion compensator array 601 .

Thereby, the residual scan distortion is reduced by at least 80%, eg by a factor of 10, and a residual scan-induced distortion of eg below 0.3 nm or even below 0.2 nm is achieved.

Figure 17 illustrates a typical field dependence of linear scan distortion vectors for a plurality of primary charged particle beamlets in the example of a multibeam charged particle microscope, where J = 61 beamlets have a hexagonal grating configuration. In images 17a, c, e and g, positive numbers are represented by circles, negative numbers are represented by squares, and the maximum or minimum value of the linear distortion vector is represented by the area of the circle or square. Fig. 17b shows the normalized linear scale SDV(1) ~ M, and Fig. 17a illustrates the linear scale SDV(1) for each of J = 61 beamlets forming image subfield center coordinates (x _nm , y _nm ) image patch correlation. Figure 17d shows the normalized squareness SDV(2)~SQ distributed over the image tile coordinates (x _nm , y _nm ) in Figure 17c. Figure 17f shows the typical normalized orthogonality SDV(3) ~ OR of the image subfield in the image subfield coordinates (p,q), and its image tile correlation is shown in Figure 17e. Fig. 17g shows the normalized rotation ROT = SDV(4) for each of the J = 61 beamlets at image coordinates (x _nm , y _nm ), and the normalized rotation is shown in Fig. 17h.

In one example, the field dependence of the linear distortion vector SDV(i) is described by a polynomial expansion of the amplitude A(i;n,m) A(i;n,m) =

描述線性掃描失真向量SDV與影像子場域中心位置的相關性。因此，掃描失真由兩多項式G和SDV的乘積描述，振幅由矩陣

描述 [dp,dq](p,q;n,m) =

where the polynomial

Describe the correlation between the linear scanning distortion vector SDV and the center position of the image subfield. Thus, the scan distortion is described by the product of two polynomials G and SDV, and the amplitude is given by the matrix

describe[dp,dq](p,q;n,m) =

描述。可在第一固定電阻陣列中實施G(j;x,y)的每個拋物線項，並在第二固定電阻陣列中實施每個掃描失真向量SDV(i)，而不是具有至少8J個可編程電阻序列的可編程電阻陣列，其中J為一次帶電粒子的數量。第一和第二固定電阻陣列依序提供給掃描失真補償器陣列601的複數個電極之電壓差，由具有3×4振幅矩陣

的可編程電阻陣列控制。 In general, the main part of the field dependence of the distortion amplitude is given by a small number of polynomials G, for example by the parabolic terms of the polynomial expansion G. In this example, the residual scan distortion is given by, for example, a 3 x 4 matrix

describe. Instead of having at least 8J programmable A programmable resistor array of resistor sequences, where J is the number of primary charged particles. The first and second fixed resistance arrays sequentially provide the voltage difference between the plurality of electrodes of the scanning distortion compensator array 601, which is composed of a 3×4 amplitude matrix

programmable resistor array control.

Using the mixing element 641 described in FIG. 14, the correction voltage provided comprises a first component proportional to the scanning voltage difference VSp(t) for scanning in the first direction of the p-coordinate in the image subfield; and A second component proportional to the scan voltage difference VSQ(t) for scanning in the second direction of the q-coordinate in the image subfield. The linear portion of the scanning-induced aberrations is thereby compensated. The driving voltage differences VCAp(t) and VCAq(t) provided at the power supply lines 609 and 610 may be subtracted from the scanning voltage differences VSp(t) and VSq(t) according to the maximum driving voltage difference required to drive the correction element. . The linear component of the linear image subfield correlation from the image subfield coordinates (p,q) is thereby compensated. The corrected or compensated amplitude for each image sub-field is provided, for example, by a static programmable resistor array 611, with each compensator or corrected electrode having a series of resistors. The higher-order part has a higher-order dependence on the aberrations caused by the scanning of the image subfield coordinates (p,q), which can be compensated by adding more voltage difference components, such as with the image subfield coordinates (p,q) A third component with a quadratic dependence, such as the product of p and q. In one example, the electrostatic voltage conversion array further includes a nonlinear voltage reduction unit or a nonlinear voltage amplifier, which generates a third driving voltage proportional to the product of the first and second driving voltage differences VCAp(t) and VCAq(t). The voltage difference VCApq(t). An example non-linear voltage step-down unit includes a source follower transistor having a first drive voltage difference VCAp(t) at the gate and a second drive voltage difference VCAq(t) at the drain, connected to an deflection electrodes. Other examples of nonlinear voltage conversion units exploit the nonlinear response of Zener diodes.

By similar setting, the dependence on image tile coordinates (xij, yij) can be compensated, and each image sub-field has at least a series of resistors. Thereby, the quadratic or higher order correlation of the maximum image subfield distortion from the image tile coordinates (xij, yij) is compensated.

In a similar way, scan compensator array 602 is operated to compensate for scan telecentricity errors during use of a multi-beam charged particle microscope. The scan-induced telecentricity error is similarly expanded into a linear component, and a control signal is derived relatively to compensate for the scan-induced telecentricity error.

Using a similar approach, the scanning compensator array for compensating scanning aberrations, such as astigmatism or defocus, is operated during use of the multi-beam charged particle microscope 1 . The scanning-induced aberrations are similarly expanded in the linear component and the control signals for the multi-beam astigmatizer array or the multi-beam lens array are derived to relatively compensate the scanning-induced aberrations.

In a similar manner, the calibration correction voltage differences VCp(t) and VCq(t) of the plurality of correction electrodes of the aggregated multi-beam raster scanner 110 according to the first embodiment can be derived and provided to the aggregated multi-beam A plurality of correction electrodes of the beam raster scanner 110 . Thereby, the residual scan distortion is reduced by at least 10%, such as by 20%, and a residual scan-induced distortion of eg below 1.5 nm is achieved.

In a similar method, the correction voltage differences VCp(t) and VCq(t) of the plurality of correction electrodes of the converging multi-beam raster scanner 110 according to the first embodiment, and the correction voltage differences VCp(t) and VCq(t) according to the second embodiment the deflection voltage differences VCAp(t) and VCAq(t) for the scan distortion compensator array 601 are derived and provided to means for correcting or compensating for scan distortion and the residual scan distortion is reduced by at least 90%, such as by 95%, And achieve, for example, residual scan-induced distortion below 0.2 nm, preferably below 0.1 nm.

According to a fifth embodiment, an improved multi-beam charged particle microscope with reduced scan distortion and an improved method of operating a multi-beam charged particle microscope with reduced scan distortion are provided. An improved multi-beam charged particle microscope includes a converging multi-beam raster scanner 110 according to a first embodiment with a predetermined non-uniform electrostatic scanning deflection field to reduce scanning distortion. The improved multi-beam charged particle microscope 1 further comprises at least a first static convergent multi-beam deflection system 701 for adjusting a plurality of primary charged particle sizes at the convergent multi-beam raster scanner 110 according to the first embodiment. beam position. Thus, distortions caused by residual scanning due to misalignment of the converged multi-beam raster scanner 110 relative to the plurality of primary charged particle beamlet raster configurations are reduced. FIG. 18 illustrates an improved multi-beam charged particle microscope 1 as an example. Some reference numbers are the same as those used in Fig. 1 . In addition to the elements described in FIG. 1, the improved multi-beam charged particle microscope according to the fifth embodiment comprises a first static convergent deflection system 701 for deflecting a plurality of primary Charged particle beamlets 3 , thereby adjusting the lateral position of the beam intersection 108 relative to the converging multi-beam raster 110 . Thereby, scanning distortion due to lateral misalignment of the plurality of primary charged particle beamlets of the convergent multi-beam raster scanner 110 relative to the transmission convergent multi-beam raster scanner 110 is further reduced.

In one example, the improved multi-beam charged particle microscope 1 according to the fifth embodiment further includes a second static convergent deflection system 703 for deflecting a plurality of primary charged particles in the transverse direction (x/y direction). beam, thereby adjusting the average propagation angle of the plurality of primary charged beamlets with respect to the optical axis. Thereby, scanning distortion due to lateral misalignment of the plurality of primary charged particle beamlets of the convergent multi-beam raster scanner 110 relative to the transmission convergent multi-beam raster scanner 110 is further reduced. The first static deflection system 701 and the second static deflection system 703 are connected to a static adjustment control unit 870, which provides a plurality of static voltage differences for adjusting a plurality of primary charged particle beamlets 3 through a converging multi-beam raster scanner The location and mean direction of propagation of the intersecting body 189 of 110.

The scan distortion is sensitive to the position and angle of propagation in which the beamlet propagates through the electrostatically scanned deflection field in the aforementioned intersecting volume. Especially for the optimized converged multi-beam raster scanner 110 according to the first embodiment of the present invention, the distortion caused by the residual scanning is very important for the converged multi-beam raster scanner 110 relative to the plurality of primary charged particle beamlets The lateral position of the beam intersection 108 of 3 is sensitive to misalignment. Through the first static deflection system 701 and the second static deflection system 703, the lateral positions and propagation angles of the plurality of primary charged particle beamlets can be adjusted.

In the improved multi-beam charged particle microscope operating method according to the fifth embodiment, the residual scan-induced distortion is measured as described in step 1 according to the fourth embodiment. The residual scan distortion is analyzed and the components of the scan distortion caused by the misalignment are determined. The static voltage is determined by the adjustment unit 870 and supplied to the first static deflection yoke 701 and the second static deflection yoke 703, and the residual scanning distortion is again measured. The residual scan distortion is analyzed and a residual scan distortion component caused by the residual misalignment is determined. This procedure is repeated until the residual scan distortion component caused by the residual misalignment is below a predetermined threshold. This adjustment method can be repeated during the operation of the multi-beam charged particle microscope, for example to compensate for aberrations caused by the scanning caused by the drift of the multi-beam charged particle microscope.

Figure 19 illustrates a typical field dependence of scan distortion caused by misalignment. In general, the scan distortion caused by misalignment has a different field dependence than the residual scan distortion of a perfectly aligned multi-beam charged particle microscope. In one example, the sensitivity of component displacement relative to the ideal position to different field dependencies of the scan distortion can be determined, and from scan distortion measurements and determination of the field dependence of the scan distortion can be deduced to achieve a perfectly tuned multi-beam charging Necessary adjustments for particle microscopes.

In a sixth embodiment, an improved multi-beam charged particle microscope is provided with a convergent multi-beam raster 110 capable of lateral displacement or tilting. In one example, lateral movement or tilting of the electrostatic deflection field by additional correction electrodes relative to the intersecting volume, or by providing a plurality of predetermined voltage offsets to the deflection electrodes and correction electrodes of the first embodiment of the present invention, is achieved. shift or tilt. In an alternative example, the converging multibeam raster scanner includes mechanical means including a guiding element or stage and at least one actuator for adjusting the lateral position or tilt angle of the deflection electrodes and selective correction electrodes relative to The electrostatic deflection field is displaced at intersection 189 .

Using additional components, lateral displacement or tilting of the non-uniform deflection field relative to the intersecting body 189 is provided, thereby enabling adjustment of the lateral position and average propagation angle of the non-uniform deflection field relative to the plurality of primary charged particle beamlets. One method is provided, for example, by generating a quadrupole or multipole field in the intersecting volume 189 in the converging deflection scanner 110 . A quadrupolar or multipolar field may be generated by applying a predetermined voltage difference to the deflection electrodes, for example a first identical voltage difference supplied to a first deflection electrode for deflecting the scan in a first direction, and a second deflection electrode for deflection scanning in a first direction. A second identical voltage difference deflects the scan in a second direction. For example, the second voltage difference is given by multiplying the first voltage difference by -1. During alignment or adjustment, the first and second voltage difference for generating the quadrupole or multipole field is varied and the central primary beamlet traveling along the optical axis 105 of the charged particle microscope 1 is monitored. The lateral position or tilt angle of the quadrupole or multipole field is then varied by varying the first and second voltage differences until the focal position of the central primary beamlet does not change during the quadrupole or multipole field change. If the quadrupole or multipole field is centered on the optical axis, the central primary beamlet will not move across the wafer when the quadrupole or multipole field strength is changed. Therefore, residual scanning distortion is minimized.

In a seventh embodiment, there is provided an improved multi-beam charged particle microscope in combination with the fifth and sixth embodiments; thus, the non-uniform electrostatic deflection field within the deflection scanner is laterally displaced relative to the intersecting volume, The non-uniform electrostatic deflection field is adjusted, for example with respect to an objective lens of a multi-beam charged particle microscope, for example by applying a predetermined offset voltage to the plurality of electrodes. Thus, scanning aberrations caused by misalignment of the raster scanner 110 and eg the objective lens 102 are compensated. Using the first and second static deflectors, the plurality of primary charged particle beamlets are then laterally adjusted relative to the adjusted position of the non-uniform electrostatic deflection field distribution.

According to various embodiments of the present invention, there is provided an improved multi-beamlet charged-particle microscopy system 1 and a method of operating the multi-beamlet charged-particle microscopy system 1 to perform high-precision and high-throughput wafer detection tasks. The improved multi-beamlet charged particle microscopy system 1 for wafer inspection has means to compensate or correct scan-induced aberrations, such as scan distortion, scan telecentricity or scan-induced astigmatism. In an eighth embodiment, the components of the preceding embodiments are combined and a maximum reduction of scanning-induced aberrations is achieved. FIG. 20 illustrates a multi-beamlet charged particle microscope 1 for wafer inspection according to an eighth embodiment. In an example of an eighth embodiment, further details of the improved multi-beamlet charged particle microscopy system 1 and the method of operation of each of the foregoing embodiments are described. The same reference numbers are used as in the previous figures and also refer to the previous figures.

The multi-beam charged particle microscope 1 for wafer inspection includes a charged particle multi-beamlet generator 300 for generating a plurality of primary charged particle beamlets 3 . The multibeam charged particle microscope 1 further comprises an object illumination unit 100 comprising a first converging multibeam raster scanner 110 for scanning each image segment on the wafer surface 25 arranged in the object plane 101. Each of the plurality of primary charged particle beamlets 3 in the field produces a plurality of secondary electron beamlets 9 emitted from the wafer surface. The plurality of secondary electron beamlets 9 are imaged by the detection unit 200 and the second convergent multi-beam raster scanner 222 for imaging the plurality of secondary electron beamlets 9 onto the image sensor 207, and A digital image of the first image tile 17 of the wafer surface 25 is acquired during use. The multi-beam charged particle microscope 1 further includes a sample stage 500 for positioning and maintaining the wafer surface 25 in the object plane 101 during the acquisition of the digital image of the first image tile 17 .

The multi-beam charged particle microscope 1 includes a control unit 800 . The control unit 800 further includes an image data acquisition unit 810 . During use, the electron sensitivity image sensor 207 receives a large image data stream of image sensor data of a plurality of secondary electron intensity values and feeds the image data to the image data acquisition unit 810 of the control unit 800 . The image data acquisition unit 810 is used for providing the sensor signal of the image sensor 207 to the image stitching unit 812 . By reducing scanning-induced aberrations, such as reducing scanning-induced distortion according to specific embodiments of the present invention, fast image stitching without digital image processing is achieved, and digital data from each image sub-field is stitched together, To form digital images of image tiles with high speed and low computational load. Thereby, the throughput of wafer inspection tasks is increased. Since the image stitching unit 812 is configured to perform fast image stitching without digital image processing, the final digital image is provided directly to the output unit 814, where the digital image is analyzed for defects or dimensions of semiconductor features, for example.

A plurality of primary charged particle beamlets 3 propagate during use through the intersecting volume 189 of the first converging multi-beam raster scanner 110 according to the first embodiment of the invention. The first scanning electrodes of the first converging multi-beam raster scanner 110 generate a first scanning deflection field distribution in the intersecting volume 189 during use for the long run scanning deflection of the plurality of primary charged particle beamlets 3 . The second scanning electrode of the first converging multi-beam raster scanner 110 generates a second scanning deflection field distribution in the intersecting volume during use for the plurality of primary charged particle beamlets 3 in the second direction or q direction (with The first direction is perpendicular to the long stroke scanning deflection. The control unit 800 includes a scan deflection control module 860 configured to generate scan deflection voltage differences VSp(t) and VSq(t) for a plurality of primary charged particle beamlets 3 in the first or p direction and the second Or scan deflection in the q direction. An example of scanning deflection voltage differences VSp(t) and VSq(t) is shown in FIG. 15 .

The control unit 800 includes an array of delay lines 862 . Scanning deflection control module 860 is configured to provide scanning deflection voltage differences VSp(t) and VSq(t) to delay line array 862, which is configured to generate a time delay between scanning deflection voltage differences VSp(t) and VSq(t). multiple copies. For example, a first copy of the scanning deflection voltage difference VSp(t) with a first time delay t1 is provided to the first converging multi-beam raster scanner 110 for scanning deflecting the plurality of primary charged particle beamlets in a first direction. bundle 3.

The first converging multi-beam raster scanner 110 further includes a correction element 112, which includes a plurality of correction electrodes according to the first embodiment, such as the correction electrodes 185, 187, 193 or 195 shown in FIGS. 8 and 10 . The correction element 112 is configured to generate a variable non-uniformity of the electrostatic deflection field distribution in the intersecting volume to reduce scanning-induced distortions during the scanning deflection of the plurality of primary charged particle beamlets 3 . The first convergent multibeam raster scanner 110 further includes a scan correction control module 120 having an electrostatic voltage conversion array connected to the scan deflection control module 860 through a delay line in a delay line array 862 . The setup of the scan calibration control module 120 is similar to the scan array control unit 622 of the second embodiment. As previously mentioned, elements and features of scan array control unit 622 in FIGS. 13 and 14 may be similarly applied to other scan correction elements, such as correction element 112 .

The delay line array 862 is configured to provide a second copy of the scan deflection voltage differences VSp(t) and VSq(t) with a second time delay t2 to the scan correction control module 120 . The scan correction control module 120 further includes a static voltage reduction unit that reduces the second copy of the scan deflection voltage differences VSp(t) and VSq(t) to the first correction voltage differences VC1p(t) and VC1q(t), Required to create a predetermined non-uniformity of electrostatic field distribution. The first correction voltage difference VC1p(t) is for example at least an order of magnitude smaller than the scanning deflection voltage difference VSp(t) for scanning deflection in the first or p direction. The static voltage conversion array of the scan calibration control module 120 generates a plurality of calibration voltage differences from the first calibration voltage differences VC1p(t) and VC1q(t). In one example, the electrostatic voltage conversion array is a programmable resistor array, as shown in FIGS. 13 and 14 . The correction voltage differences are formed as correction electrodes of the correction element 112 . The programmable resistor array of the scan calibration control module 120 is controlled by a plurality of first static control signals, and these signals are stored in the memory of the scan calibration control module 120 . During the calibration step, the plurality of first static control signals may be changed by the beam path control module 830 once.

The delay line array 862 is further configured to provide a third copy of the scanning deflection voltage difference VSp(t) and VSq(t) with a third time delay t3 to the second convergent multi-beam raster scanner 222 for scanning the plurality of two Secondary electron beamlets9. Thereby, the beam spot of the secondary electron beamlet 9 remains constant at the image detector 207 .

According to a second embodiment of the present invention, the multi-beam charged particle microscope 1 comprises a scanning distortion compensator array 601 with a first scanning array control unit 622.1. The first scan array control unit 622.1 is connected to the scan deflection control module 860 via a delay line array 862. The delay line array 862 is configured to provide a fourth copy of the scan deflection voltage difference VSp(t) and VSq(t) with a fourth time delay t4 to the first scan array control unit 622.1. The first scan array control unit 622.1 includes a static voltage reduction unit that reduces a fourth copy of the scan deflection voltage differences VSp(t) and VSq(t) to the second correction voltage differences VC2p(t) and VC2q(t) , required for generating a predetermined maximum deflection of the beamlets by scanning the distortion compensator array 601 . The second correction voltage difference VC2p(t) is for example at least two orders of magnitude smaller than the scanning deflection voltage difference VSp(t) for scanning deflection in the first or p direction. In the above description, VCap(t) is used as a notation for VC2p(t).

According to a third embodiment of the present invention, the multi-beam charged particle microscope 1 includes a scanning compensator array 602 for compensating telecentricity errors caused by scanning. The scan compensator array 602 includes a second scan array control unit 622.2. The second scan array control unit 622.2 is connected to the scan deflection control module 860 via a delay line array 862. The delay line array 862 is configured to provide a fifth copy of the scan deflection voltage differences VSp(t) and VSq(t) with a fifth time delay t5 to the second scan array control unit 622.2. The second scan array control unit 622.2 includes a static voltage reduction unit that reduces a fifth copy of the scan deflection voltage differences VSp(t) and VSq(t) to third correction voltage differences VC3p(t) and VC3q(t), A predetermined maximum correction for the beamlet propagation angle is generated by the scanning compensator array 602 as needed to compensate for scanning induced telecentricity errors. The third correction voltage difference VC3p(t) is for example at least two orders of magnitude smaller than the scanning deflection voltage difference VSp(t) for scanning deflection in the first or p direction.

By providing a plurality of copies of the scan deflection voltage differences VSp(t) and VSq(t) with a plurality of predetermined time delays, the plurality of charged particle small The scan deflection of beam 3 is synchronized to compensate for aberrations caused by the scan. The first to fifth time delays t1 . . . t5 are eg determined during design and adjusted in a setup or calibration step of the multi-beam charged particle microscope 1 and stored in the delay line array 862 .

The multi-beam charged particle microscope 1 of the eighth embodiment further includes a first static deflector 701 according to the fifth embodiment of the present invention, which is connected to the primary beam path control module 830 . The static adjustment control unit 870 illustrated in FIG. 18 may be part of the primary beam path control module 830 . During the calibration step, the lateral positions of the plurality of primary charged particle beamlets at the first converging multi-beam raster scanner 110 are determined. During use, the multibeam charged particle microscope 1 is configured to adjust the lateral position of the plurality of primary charged particle beamlets at the intersection 189 of the first converging multibeam raster scanner 110 and the first static deflector 701 . The multi-beam charged particle microscope 1 includes a second static deflector 703 connected to the primary beam path control module 830 . During the calibration step, the average angle of incidence of the plurality of primary charged particle beamlets at the first converging multi-beam raster scanner 110 is determined. During use, the multibeam charged particle microscope 1 is configured to adjust the average angle of incidence of the plurality of primary charged particle beamlets 3 at the intersection 189 of the first converging multibeam raster scanner 110 and the second static deflector 703 .

The scan correction control module 120 and the first and second scan array control units 622.1 and 622.2 are further connected to the primary beam path control module 830, wherein the static control for the static voltage conversion unit is adjusted according to the calibration results or by other means. The signal is as described in the fourth embodiment of the present invention. The primary beam path control module 830 is connected to a control operations processor 840 which derives, for example from calibration measurements according to the fourth embodiment, a set of actual static control signals from the calibration step, including the measurement step of the scanning-induced distortion.

In one example, the image stitching unit 812 is connected to the control operation processor 840 , and the image stitching unit 812 is configured to derive and provide the stitching quality parameter to the control operation processor 840 . If the stitch quality parameter is below a predetermined threshold, the control operations processor 840 is configured to initiate calibration of the multi-beam charged particle microscope 1 to generate a set of actual control signals for compensating for scanning-induced distortions. An example of a stitching quality parameter is the image contrast in the overlapping region 39 of two adjacent image sub-fields, as shown in FIG. 2 . Since the scanning-induced aberrations are reduced, for example below 0.3 nm, preferably below 0.1 nm, image stitching without digital image processing is also possible and by superimposing digital image data from two image sub-fields in the overlap region 39 Overlapping image stitching produces high image contrast. Distortions caused by residual scans such as drift or misalignment of the multi-beam charged particle microscope 1 degrade the image contrast in the overlapping region 39 . The image contrast in the overlapping area 39 is an example of a stitching quality parameter and can be taken as an indicator of the quality of compensation or correction of scanning-induced aberrations and thus of eg drift or misalignment of the multi-beam charged particle microscope 1 . In a calibration step, the scan-induced aberrations are determined for each image subfield. For example, the control operation processor 840 is configured to analyze the scanning-induced distortion [dp,dq](p,q;xij,yij), for example, by unfolding the scanning-induced distortion as described in the fourth embodiment, And the control operation processor 840 is configured to derive a plurality of actual static control signals to the correction element 112 of the converging multibeam raster scanner 110, the scanning distortion compensator array 601, the telecentric aberration scanning compensator array 602, the first static multi-beam A beam deflection system 701 and a second static multi-beam deflection system 703 . The control operations processor 840 is configured to provide a plurality of actual static control signals to the primary beam path control module 830 configured to provide a plurality of actual static control signals to individual compensators or corrections of the multi-beam charged particle microscope 1 Element 112, 601, 602, 701 or 701.

The foregoing embodiments are preferably applied to the primary beam path 13 to compensate for aberrations caused by scanning or scanning of a plurality of primary charged particles 3 . However, it is also possible to apply the embodiment to the secondary beam path 11 in order to correct eg scanning induced contrast changes. Please refer to Figure 1 now. The plurality of secondary electron beamlets are deflected and scanned by the combined deflection of first convergent multibeam rasterizer 110 and second convergent multibeam rasterizer 222 , and the image contrast is controlled, for example, by aperture filter 214 . Aberrations caused by scanning in the secondary beam path 11, for example, telecentric aberrations caused by scanning of the secondary electron beamlet 11 lead to changes in contrast caused by scanning, which can be achieved by means similar to the second or third specific embodiment A multi-beam scanning correction system is used to compensate for this, for example configured in the secondary beam path 11 at the location of the element 220 .

With multi-beam charged particle microscopy and multi-beam charged particle microscope operating methods such as compensation for distortions caused by scanning. A converging multi-beam rasterizer (110) forms an intersecting volume (189) and is configured to perform a converging rastering of a plurality of primary beamlets (3) to form an image scan of an image tile (17). The plurality of primary beamlets comprises at least a first primary beamlet (3.55) scanned over at least a first image subfield (31.55) and a second image subfield (31.15) in an image tile (17) The second small beam (3.15) of the upper synchronous scan. The first primary beamlet traverses the intersection body (189) at a first angle 1, and the second primary beamlet traverses the intersection body (189) at a second angle 2 different from the first angle 1. Thus, with conventional raster scanners and conventional methods of raster scanner operation, a significant difference arises in the distortion induced by the scanning between the first beamlet and the second beamlet. The first scan corrector (601) is connected to the control unit (800), the first primary beamlet (3.55) in the first image subfield (31.55) and the first primary beamlet (31.55) in the second image subfield (31.55) The distortion difference caused by scanning between the two primary beamlets (3.15) is reduced. In addition, similar to the distortion difference caused by scanning, the first primary beamlet (3.55) in the first image subfield (31.55) is different from the second primary beamlet in the second image subfield (31.15) The telecentric difference caused by the scanning between (3.15) is compensated by the second scanning compensator array of the telecentric aberration 602 .

The first convergent raster scanner 110 is configured to scan each beamlet Do long stroke raster scan. The first scan corrector (601) forms a second short-stroke raster scanner by which distortions caused by the scanning of each beamlet are individually corrected with a small scanning range, for example up to 5 nm. Thereby, the distortion caused by scanning is reduced and the raster scanning coordinates are realized with an accuracy better than 3 orders of magnitude, for example, for a scanning coordinate of 5.0 μm, the accuracy is better at 0.5 nm, preferably 0.3 nm or even lower.

The invention is important for multi-beam charged particle systems when multiple primary charged particle beamlets pass through the intersecting volume at different angles. The multi-beam charged particle microscope includes a multi-beamlet generator for generating a plurality of primary beamlets. In this multi-beam charged particle microscope (1), the beamlet generator generates at least first and second primary charged particle beamlets (3.0, 3.1, 3.2), and the first scan corrector further comprises a plurality of deflection elements configured to individually compensate during use, for example, distortions caused by the scanning of the second primary charged particle beamlet (3.1 or 3.2). The multi-beam charged particle microscope further includes an object irradiation unit for illuminating a plurality of image sub-fields, through which a plurality of primary small beams form image blocks together on the sample surface arranged in the object plane, so that during use generating a plurality of secondary electron beamlets emitted from the surface; and a detection unit having a projection system and an image sensor for imaging the plurality of secondary electron beamlets to the image sensor , to acquire a digital image of the sample surface image tile during use. The multi-beam microscope for wafer inspection according to an embodiment further includes a converged multi-beam raster scanner. The converging multi-beam raster scanner includes at least a first set of deflection electrodes and an intersection body between the first set of deflection electrodes, through which a plurality of primary beamlets pass through the intersection body. The intersecting body is designed to transmit a plurality of primary beamlets impinging on the intersecting body at different angles of incidence. The multi-beam charged particle microscope further includes at least one first scan corrector or compensation element for correcting aberrations caused by scanning. The first scan corrector is configured, during use, to generate a first scan electrostatic field to affect at least the first individual beamlet.

A multi-beam charged particle microscope according to an embodiment of the present invention comprises a beamlet generator for generating a plurality of beamlets of primary charged particles, a surface 25 for illuminating the sample 7 arranged in the object plane 101 The object irradiation unit 100 of the upper image subfields, thereby generating during use a plurality of secondary electron beamlets 9 emitted from the focal point 5 of the primary beamlets 3 in each image subfield. The subfields generally have a lateral extension of at least 5 μm, preferably 8 μm, 12 μm or more. The object irradiation unit 100 further includes first to third electrostatic or magnetic lenses and an objective lens 102 . The multi-beam charged particle microscope 1 further includes a detection unit 200 for acquiring digital images of each image sub-field on the sample surface during use. The detection unit 200 includes an electronic sensor 207 and an optional electrostatic or electromagnetic deflection element 222 . The multi-beam charged particle microscope 1 further includes an electromagnetic beam splitting system 400 for directing the primary beamlet 3 on the primary beam path 13 and guiding the secondary beamlet 9 on the secondary beam path 11 . The secondary beamlet 9 collected by the objective lens 102 propagates opposite to the primary beamlet 3 and is thus separated from the primary beamlet 3 by the magnetic beam splitting system 400 .

According to a specific embodiment, the multi-beam charged particle microscope 1 for wafer inspection further includes a long-stroke convergent grating scanner 110, and the convergent grating scanner 110 includes at least a first set of deflection electrodes (181) and an intervening first The intersecting body 189 between the set of deflection electrodes (181), through which a plurality of small beams 3 of primary charged particles pass. The charged particle microscope 1 for wafer inspection according to the ninth embodiment further comprises a control unit 800 configured to provide at least a first scanning voltage difference VSp(t) to the first group of deflection electrodes (181) during use ), for generating an electrostatic deflection field in the intersecting body 189 for the long-range scanning deflection of the plurality of first primary charged particle beamlets 3 in the first or p direction, so that during use the entire image subfield The beamlet is scanned once over a domain extending beyond 1 μm, for example about 8-10 μm.

The multi-beam charged particle microscope 1 further includes at least one first scan corrector 112 for correcting aberrations caused by the scanning of a plurality of primary charged particle beamlets 3 . The first scan corrector 112 is configured to generate a first scan electrostatic field during use to affect the plurality of primary beamlets 3, and the control unit 800 is further configured to provide a first scan voltage difference VSp(t) to the first scan corrector 112, the first scan corrector configured to reduce aberrations caused by scanning of at least a first primary charged particle beamlet 3.1. In one example, the first scan corrector 112 includes a first static voltage conversion unit for converting the first scan voltage difference VSp(t) into at least one first scan correction voltage difference VCp(t), which is adapted to The first scanning correction field synchronized with the first scanning voltage difference VSp(t) is generated by the scanning correction electrode 185 . As mentioned above, the static voltage conversion unit may include at least one programmable resistor series configured to be programmed by a plurality of static control signals for generating the scanning correction voltage difference VCp(t). Therefore, the first scan corrector 112 is connected to the primary beam path control module 830 . In one example, the first static voltage converting unit is configured to generate the first scanning correction voltage difference VCp(t) which is proportional or linearly related to the first scanning voltage difference VSp(t). In order to correct the aberration caused by synchronous scanning, the control unit 800 further includes a delay line array 862, including at least one first delay line, which is configured to make the first scanning correction field pass through the raster scanner (110) and a plurality of primary charged Multiple long-range scanning deflections of particle beamlets 3 are synchronized. With the aforementioned elements, the first scan corrector 112 comprising at least one first short-stroke deflection element 185 is configured to compensate for scan-induced aberrations during use, for example by an amount of about 0.5 nm to 3 nm to Astigmatism caused by residual scanning below 0.3 nm, preferably below 0.2 nm or 0.1 nm. In one example, the first correction element 185 is configured to individually compensate for the astigmatism caused by the scanning of the first primary charged particle beamlet 3.1 during use, so as to be aligned with the first primary charged particle beamlet 3.1 by the raster scanner 1110 in the first direction. The scan deflection of particle beamlet 1003 is synchronized.

In another example, residual distortion is compensated. When the primary beamlet 3.1 passes through the long-stroke scanning deflector 110 and scans over the image sub-field extending beyond 1 μm, the first scan corrector 112 acts as a synchronous short-stroke deflector during use, passing through the primary beamlet 3.1 The beam 3.1 is deflected in the opposite direction of the scan-induced distortion by a synchronous short-stroke scan to compensate for the scan-induced distortion up to approximately 5 nm. In one example, the first scan corrector 112 includes a second corrector element 187 configured to individually compensate, during use, distortions caused by the scan of the first primary charged particle beamlet 3.1 in the second direction, which is identical to The scanning deflection of the first primary charged particle beamlet 3.1 by the convergent raster scanner 110 in the first direction perpendicular to the second direction is synchronized.

The multi-beam charged particle microscope 1 with reduced scanning-induced aberrations according to the ninth embodiment comprises a long-range deflection system 110 for long-range deflection of a plurality of primary charged particle beamlets 3, which are applied to The deflection voltage difference VSp(t) generation of the deflection yoke 110; and a scanning correction system for correcting the aberrations caused by the scanning of each individual beamlet of the plurality of primary beamlets, which provides the correction voltage during use Difference VC(t). The correction voltage difference VC(t) is generated from the deflection voltage difference Vp(t) using a static voltage conversion unit, such as a programmable resistor series or array, controlled by a set of static control signals. Thus, aberrations induced by small scans of eg 0.5 nm to 5 nm are effectively reduced to residual aberrations below 0.3 nm, preferably below 0.2 nm or even below 0.1 nm.

The invention and some specific embodiments may be further described using the following various sub-items. However, the present invention should not be limited to the following sub-items.

Subitem 1: A multi-beam charged particle microscope (1) for wafer inspection comprising: Charged particle multi-beamlet generator (300), used to generate a plurality of primary charged particle beamlets (3); An object irradiation unit (100) for irradiating an image block (17.1) arranged on the wafer surface (25) in the object plane (101) by means of a plurality of primary charged particle beamlets (3), thereby generating during use a plurality of secondary electron beamlets (9) emanating from the wafer surface (25), A detection unit (200), which has a projection system (205) and an image sensor (207), for imaging the plurality of small secondary electron beams (9) on the image sensor (207 ) and for acquiring a digital image of the image tile (17.1) of the wafer surface (25) during use; A converging multi-beam raster scanner (110) comprising at least a first set of deflection electrodes and an intersecting body (189) through which the plurality of primary charged particle beamlets (3) pass during use (189); a control unit (800) configured to provide, during use, at least a first scanning voltage difference VSp(t) to the first set of deflection electrodes for scanning deflecting the plurality of primary charged particles in the first or p direction beamlet(3), Wherein the converging multi-beam raster scanner (110) is configured to generate a predetermined non-uniform scanning deflection field distribution in the intersecting body (189) to reduce the Aberrations caused by scanning of the first charged particle beamlet incident on the intersecting volume (189).

Sub-item 2: The multi-beam charged particle microscope (1) of sub-item 1, wherein a deflection electrode of the first set of deflection electrodes consists of two spaced apart electrodes, and the control unit (800) is configured to During use, first and second scanning voltage differences VSp1(t) and VSp2(t) are supplied to the two spaced apart electrodes, wherein the first and second scanning voltage differences VSp1(t) and VSp2(t) are different.

Sub-item 3: The multi-beam charged particle microscope (1) of sub-item 1 or 2, wherein the converging multi-beam scanning raster (110) comprises a second set of deflection electrodes for generating, during use a second predetermined non-uniform scanning deflection field distribution through which a plurality of primary charged particle beamlets (3) pass through the intersection body (189) to scan in the second or q direction deflecting the plurality of primary charged particle beamlets (3); and the control unit (800) configured, during use, to provide at least a second scanning voltage difference VSq(t) to the second set of deflection electrodes.

Sub-item 4: The multi-beam charged particle microscope (1) as described in sub-item 3, wherein the shape and geometry of the at least one first or second set of deflection electrodes of the converging multi-beam raster scanner (110) The shape is adapted to the section of the intersecting body (189).

Sub-item 5: The multi-beam charged particle microscope (1) as described in sub-item 3 or 4, wherein in the average propagation direction of the plurality of primary charged particle beamlets (3), the first set of deflection electrodes and The second set of deflection electrodes has different lengths.

Sub-item 6: The multi-beam charged particle microscope (1) of any one of sub-items 1 to 5, wherein the convergent multi-beam raster scanner (110) further comprises a first set of correction electrodes (185, 193) which during use produces a predetermined scanning correction field which contributes to the predetermined non-uniform electrostatic field distribution.

Sub-item 7: The multi-beam charged particle microscope (1) as described in sub-item 6, wherein the electrodes (185.1, 185.2, 185.3, 185.4) of the first set of correction electrodes are arranged between the electrodes of the first set of deflection electrodes and The intersecting body (189) in the interelectrode space of the second set of deflection electrodes is outside.

Sub-item 8: The multi-beam charged particle microscope (1) according to any one of sub-items 6 or 7, wherein the convergent multi-beam raster scanner (110) further comprises a second set of correction electrodes (187, 195) configured to generate, during use, a predetermined second scan correction field that contributes to the predetermined non-uniform electrostatic field distribution.

Sub-item 9: The multi-beam charged particle microscope (1) of any one of sub-items 1 to 8, wherein the converging multi-beam raster scanner (110) is configured to adjust a predetermined non- The lateral position of the deflection field distribution is scanned uniformly, and the control unit (800) provides a voltage offset during use to at least one of the deflection electrodes of the first set or the deflection electrodes of the second set.

Sub-item 10: The multi-beam charged particle microscope (1) as described in any one of sub-items 1 to 9, which further includes the charged particle multi-beamlet generator (300) and the converging multi-beam A first static deflection system (701) between the raster scanners (110), configured to adjust the lateral position of the plurality of primary charged particle beamlets (3) relative to the intersection body (189).

Sub-item 11: The multi-beam charged particle microscope (1) as described in any one of sub-items 1 to 10, which further includes the charged particle multi-beamlet generator (300) and the converging multi-beam A second static deflection system (701) between the raster scanners (110) is used to adjust the average incidence angle of the plurality of primary charged particle beamlets (3) on the entrance of the intersecting body (189).

Sub-item 12: The multi-beam charged particle microscope (1) of any one of sub-items 1 to 11, further comprising a scanning distortion compensator array (601) having a plurality of deflection elements and a first scanning array control unit (622.1) having a first electrostatic voltage conversion array, for providing a plurality of first correction voltage differences to each of a plurality of deflection elements, so as to compensate for Aberrations induced by the scanning of each of the primary charged particle beamlets (3).

Sub-item 13: The multi-beam charged particle microscope (1) of sub-item 12, wherein each of the plurality of first correction voltage differences is connected to a scanning voltage via the first scanning array control unit (622.1) difference at least one of VSp(t) or VSq(t) to scan the plurality of primary charged particle beamlets (3) by the convergent multi-beam raster scanner (110).

Sub-item 14: The multi-beam charged particle microscope (1) according to any one of sub-items 1 to 13, which further comprises a scanning compensator array (602), used to compensate telecentric aberration caused by scanning, It is arranged near the intermediate image plane (321) of the multi-beam charged particle microscope (1), and the scanning compensator array (602) has a plurality of deflection elements arranged on a plurality of apertures and a second electrostatic voltage conversion array The second scanning array control unit (622.2) is used to provide a plurality of second correction voltage differences to each of a plurality of deflection elements to compensate for scanning the primary charged particle beamlets (3) during image scanning The telecentric aberration caused by each.

Sub-item 15: The multi-beam charged particle microscope (1) of sub-item 14, wherein each of the plurality of second correction voltage differences comprises at least one of the scanning voltage differences VSp(t) or VSq(t) connected to A voltage difference is used to scan the plurality of primary charged particle beamlets (3) by the converging multi-beam raster scanner (110).

Subitem 16: A multi-beam charged particle microscope (1) for wafer inspection, comprising: Charged particle multi-beamlet generator (300), used to generate a plurality of primary charged particle beamlets (3); an object irradiation unit (100) for irradiating an image patch (17.1) arranged on the wafer surface (25) in the object plane (101) by means of the plurality of primary charged particle beamlets (3), thereby generating, during use, a plurality of secondary electron beamlets (9) emanating from the wafer surface (25); A detection unit (200), which has a projection system (205) and an image sensor (207), for imaging the plurality of small secondary electron beams (9) on the image sensor (207 ) and for acquiring a digital image of the image tile (17.1) of the wafer surface (25) during use; a converging multi-beam raster scanner (110); A scanning distortion compensator array (601) having a plurality of apertures arranged upstream of the converging multi-beam raster scanner (110) in the propagation direction of the plurality of primary charged particle beamlets, each of the plurality of apertures or transmit a respective one of the plurality of primary charged particle beamlets during use, the plurality of apertures comprising a plurality of first deflection elements for deflecting individually in the first or p direction each respective primary charged particle beamlet; and the plurality of apertures includes a plurality of second deflection elements for individually deflecting each respective primary charged particle beamlet in a second or q direction perpendicular to the first direction beams, each of the plurality of deflection elements disposed within the perimeter of each of the plurality of apertures; a control unit (800) which, during use, provides at least a first scanning voltage difference VSp(t) to the converging multi-beam raster scanner (110) for scanning deflecting the a plurality of primary charged particle beamlets (3); Wherein the scanning distortion compensator array (601) further includes a scanning array control unit (622), which has a first static voltage conversion array (611), configured to provide a plurality of first correction voltage differences to a plurality of the first The deflection element, and having a second electrostatic voltage conversion array (612), is configured to provide a plurality of second correction voltage differences to the plurality of second deflection elements, so as to compensate the plurality of primary charged particle beamlets (3) in Aberrations induced by scanning during scanning deflection in the first direction.

Sub-item 17: The multi-beam charged particle microscope (1) for wafer inspection according to sub-item 16, wherein the first electrostatic voltage conversion array (611) is coupled to the control unit (800), and At least a plurality of first voltage difference components synchronized with the first scanning voltage difference VSp(t) are supplied to each of the plurality of first and second deflection elements.

Sub-item 18: The multi-beam charged particle microscope (1) for wafer inspection as described in sub-item 16 or 17, wherein the control unit (800) changes a second scanning voltage difference VSq(t) during use to The converging multi-beam raster scanner (110) is provided for scanning deflecting the plurality of primary charged particle beamlets (3) in the second or q direction.

Sub-item 19: The multi-beam charged particle microscope (1) for wafer inspection as described in sub-item 18, wherein the first electrostatic voltage conversion array (611) and the second electrostatic voltage conversion array (612) are coupled connected to the control unit (800), and providing at least a plurality of second voltage differential components synchronized with the second scanning voltage difference VSq(t) to each of the plurality of first and second deflection elements.

Sub-item 20: The multi-beam charged particle microscope (1) for wafer inspection as described in sub-item 18 or 19, wherein the first electrostatic voltage conversion array (611) is coupled to the control unit (800), and supplying at least a first voltage difference component synchronized with the first scan voltage difference VSp(t) and a second voltage difference component synchronized with the second scan voltage difference VSq(t) to the plurality of first deflection elements each of them.

Sub-item 21: The multi-beam charged particle microscope (1) according to any one of sub-items 16 to 20, wherein the first or second electrostatic voltage conversion array (611, 612) is configured as a programmable resistor array.

Sub-item 22: The multi-beam charged particle microscope (1) of any one of sub-items 16 to 20, wherein the convergent multi-beam raster scanner (110) comprises at least a first set of deflection electrodes and intersecting volumes (189), the plurality of primary charged particle beamlets (3) passing through the intersecting volume (189), wherein the converging multi-beam rasterizer (110) is configured to generate a predetermined non-uniform scanning deflection field distribution to reduce the image caused by the scanning of a primary charged particle beamlet incident on the intersecting body (189) at an inclination angle β deviating from the optical axis of the multi-beam charged particle microscope (1) Difference.

Sub-item 23: The multi-beam charged particle microscope (1) of sub-item 22, wherein the deflection electrodes of the first set of deflection electrodes consist of two spaced apart electrodes, and the control unit (800) during use providing the first scanning voltage difference VSp1(t) and the second scanning voltage difference VSp2(t) to the two spaced-apart electrodes, wherein the first scanning voltage difference VSp1(t) and the second scanning voltage difference VSp2 (t) different.

Sub-item 24: The multi-beam charged particle microscope (1) of sub-item 22 or 23, wherein the converging multi-beam scanning raster (110) comprises a second set of deflection electrodes for generating in use a second predetermined non-uniform scanning deflection field distribution, a plurality of primary charged particle beamlets (3) pass through the second predetermined non-uniform scanning deflection field distribution in the intersecting body (189) to The upscan deflects the plurality of primary charged particle beamlets (3).

Sub-item 25: The multi-beam charged particle microscope (1) of sub-item 24, wherein the shape and geometry of the at least one first or second set of deflection electrodes of the converging multi-beam raster scanner (110) are adapted Become the section of this intersecting body (189).

Sub-item 26: The multi-beam charged particle microscope (1) as described in sub-item 24 or 25, wherein in the average direction of propagation of the plurality of primary charged particle beamlets (3), the first set of deflection electrodes and The second set of deflection electrodes has different lengths.

Sub-item 27: The multi-beam charged particle microscope (1) of any one of sub-items 16 to 26, wherein the convergent multi-beam raster scanner (110) further comprises a first set of correction electrodes (185, 193) which during use produces a predetermined scanning correction field which contributes to the predetermined non-uniform electrostatic field distribution.

Sub-item 28: The multi-beam charged particle microscope (1) as described in sub-item 27, wherein the electrodes (185.1, 185.2, 185.3, 185.4) of the first set of correction electrodes are arranged between the electrodes of the first set of deflection electrodes and the first set of deflection electrodes In the space between the electrodes of the two sets of deflection electrodes.

Sub-item 29: The multi-beam charged particle microscope (1) of any one of sub-items 27 or 28, wherein the convergent multi-beam raster scanner (110) further comprises a second set of correction electrodes (187, 195 ), which during use produces a predetermined second scanning correction field that contributes to the predetermined non-uniform electrostatic field distribution.

Sub-item 30: The multi-beam charged particle microscope (1) of any one of sub-items 16 to 29, wherein the converging multi-beam raster (110) is configured to adjust a predetermined non- The lateral position of the deflection field distribution is scanned uniformly, and the control unit (800) provides a voltage offset during use to at least one of the deflection electrodes of the first set or the deflection electrodes of the second set.

Sub-item 31: The multi-beam charged particle microscope (1) as described in any one of sub-items 16 to 30, which further includes the charged particle multi-beamlet generator (300) and the converging multi-beam A first static deflection system (701) between the raster scanners (110), configured to adjust the lateral position of the plurality of primary charged particle beamlets (3) relative to the intersection body (189).

Sub-item 32: The multi-beam charged particle microscope (1) as described in any one of sub-items 16 to 31, which further includes the charged particle multi-beamlet generator (300) and the converging multi-beam A second static deflection system (701) between the raster scanners (110) is used to adjust the average incidence angle of the plurality of primary charged particle beamlets (3) on the entrance of the intersecting body (189).

Sub-item 33: The multi-beam charged particle microscope (1) according to any one of sub-items 16 to 32, which further comprises a scanning compensator array (602) for compensating telecentric aberration caused by scanning, It is arranged near the intermediate image plane (321) of the multi-beam charged particle microscope (1); the scanning compensator array (602) has a plurality of deflection elements arranged on a plurality of apertures and has a second electrostatic voltage conversion a second scanning array control unit (622.2) of the array for providing a plurality of second correction voltage differences to each of the plurality of deflection elements to compensate for scanning the primary charged particle beamlets during image scanning (3) The telecentric aberration caused by each.

Sub-item 34: A multi-beam charged particle microscope (1) according to any one of sub-items 16 to 33, further comprising a further array of scanning compensators for compensating scanning induced aberrations such as Astigmatism or focal plane deviation caused by the scanning of each of the plurality of primary charged particle beamlets (3).

Sub-item 35: A multi-beam charged particle microscope (1) for wafer inspection, comprising: Charged particle multi-beamlet generator (300), used to generate a plurality of primary charged particle beamlets (3); an object irradiation unit (100) for irradiating an image patch (17.1) arranged on the wafer surface (25) in the object plane (101) by means of the plurality of primary charged particle beamlets (3), thereby generating, during use, a plurality of secondary electron beamlets (9) emanating from the wafer surface (25); A detection unit (200), which has a projection system (205) and an image sensor (207), for imaging the plurality of small secondary electron beams (9) on the image sensor (207 ) and for acquiring a digital image of the image tile (17.1) of the wafer surface (25) during use; A converging multi-beam raster scanner (110) having at least a first set of deflection electrodes and an intersecting body (189) through which the plurality of primary charged particle beamlets (3) pass during use (189); a control unit (800) configured to provide, during use, at least a first scanning voltage difference VSp(t) to the convergent multi-beam raster scanner (110) for scanning deflection in the first or p direction a plurality of primary charged particle beamlets (3); a first static deflection system (701), arranged between the charged particle multi-beamlet generator (300) and the converging multi-beam raster scanner (110), configured to adjust the plurality of primary charged The lateral position of the particle beamlet (3) relative to the intersection volume (189).

Sub-item 36: The multi-beam charged particle microscope (1) as described in sub-item 35, which further includes the charged particle multi-beamlet generator (300) and the converging multi-beam raster scanner (110) A second static deflection system (701) in between is used to adjust the average incident angle of the plurality of primary charged particle beamlets (3) on the entrance of the intersecting body (189).

Sub-item 37: A method of operating a multi-beam charged particle microscope (1), the microscope having a charged particle multi-beamlet generator (300), an object irradiation unit (100), a detection unit (200), for detecting A convergent multi-beam raster scanner (110) for performing convergent raster scanning on a plurality of small primary charged particle beams (3), and the convergent multi-beam raster scanner arranged in the propagating direction of the plurality of small primary charged particle beams (110) upstream scanning distortion compensator array (601), and a control unit (800), which comprises the following steps: providing at least a first scanning voltage difference VSp(t) to a scanning array control unit (622); generating a plurality of voltage differential components from at least the first voltage difference VSp(t) and a plurality of control signals; providing the plurality of voltage differential components to the plurality of deflection elements of the scanning distortion compensator array (601) to individually scan and deflect each beamlet of the plurality of primary charged particle beamlets to compensate Distortion caused by multiple scans during one scan deflection of a charged particle beamlet (3).

Sub-item 38: The operation method of the multi-beam charged particle microscope (1) as described in sub-item 37, which further includes the following steps: determining scanning-induced distortion by scanning the plurality of primary charged particles on an image patch of a reference object; extracting a plurality of amplitudes of at least one linear portion of each of the plurality of scans of the primary charged particle beamlet induced distortion; deriving a plurality of control signals from each of the plurality of amplitudes; The plurality of control signals are provided to the scanning array control unit of the scanning distortion compensator array (601).

Sub-item 39: A multi-beam microscope (1) for wafer inspection, comprising: A multi-beamlet generator (300) for generating a plurality of primary beamlets (3), including at least one first individual beamlet; An object irradiation unit (100) for irradiating with the plurality of primary beamlets (3) an image patch (17.1) arranged on the sample surface (25) in the object plane (101) so as to generate during use a plurality of secondary electron beamlets (9) emanating from the surface (25); A detection unit (200), which has a projection system (205) and an image sensor (207), for imaging the plurality of small secondary electron beams (9) on the image sensor (207 ) and for acquiring a digital image of the image tile (17.1) of the surface (25) during use; a converging multibeam raster scanner (110) comprising at least a first set of deflection electrodes and an intersecting body (189) through which the plurality of primary beamlets (3) pass; at least one first scan corrector configured, during use, to generate a first scan electrostatic field to affect at least the first individual beamlet; a control unit (800) configured to provide, during use, at least a first scanning voltage difference VSp(t) to the first set of deflection electrodes for collectively raster scanning the plurality of once in the first or p direction beamlet(3), Wherein the control unit (800) further provides the first scan voltage difference VSp(t) to the first scan corrector, and the first scan corrector reduces aberrations caused by scanning of at least the first individual beamlet.

Sub-item 40: The multi-beam charged particle microscope (1) as described in sub-item 39, wherein the first scan corrector comprises a first static voltage conversion unit for the first scan voltage difference VSp(t) Converted to at least one first scanning correction voltage difference VCp(t) adapted to generate the first scanning electrostatic field synchronously with the first scanning voltage difference VSp(t).

Sub-item 41: The multi-beam charged particle microscope (1) according to sub-item 40, wherein the static voltage conversion unit comprises at least one programmable resistor series configured to be programmed by a plurality of static control signals.

Sub-item 42: The multi-beam charged particle microscope (1) as described in sub-item 40 or 41, wherein the first static voltage conversion unit generates the first scan proportional to the first scan voltage difference VSp(t) Correct the voltage difference VCp(t).

Sub-item 43: The multi-beam charged particle microscope (1) according to any one of sub-items 39 to 42, wherein the control unit (800) further comprises a first delay line which makes the first scan corrector The field is synchronized with the convergent rastering of the plurality of primary beamlets (3) by the convergent multi-beam raster scanner (110).

Sub-item 44: The multi-beam charged particle microscope (1) of any one of sub-items 39 to 43, wherein the first scan corrector comprises a plurality of deflection elements configured to compensate during use The distortion caused by the scanning of each primary beamlet of the plurality of primary beamlets (3).

Sub-item 45: The multi-beam charged particle microscope (1) of sub-item 44, wherein the plurality of deflection elements comprises a first deflection element which during use individually compensates the first individual beamlets along The distortion caused by scanning in the first direction is synchronized with the scanning deflection of the plurality of primary beamlets (3) in the first direction by the converging multi-beam raster scanner (110).

Sub-item 46: The multi-beam charged particle microscope (1) of sub-item 45, wherein the plurality of deflection elements further comprise a second deflection element which, during use, individually compensates the first individual beamlets for The distortion caused by the scanning in the second direction is related to the scanning of the plurality of primary beamlets (3) in the first direction perpendicular to the second direction by the converging multi-beam raster scanner (110) deflection synchronization.

Sub-item 47: A multi-beam charged particle microscope (1) as described in sub-item 45 or 46, wherein the plurality of deflection elements further comprises a third deflection element which individually compensates the second individual beamlets during use The distortion caused by the scanning of the beams in the first direction is synchronized with the scanning deflection of the plurality of primary beamlets (3) in the first direction by the converging multi-beam raster scanner (110).

Sub-item 48: The multi-beam charged particle microscope (1) of any one of sub-items 44 to 47, wherein the static voltage conversion unit comprises a plurality of programmable resistor series, each programmable resistor series connected to a plurality of A deflection element among the deflection elements, the plurality of programmable resistance arrays form a programmable resistance array controlled by a plurality of static control signals, which generate a plurality of scanning correction voltage differences VCap(i,t) during use, each time A scanning correction voltage difference is synchronized with the first scanning voltage difference VSp(t).

Sub-item 49: The multi-beam charged particle microscope (1) of any one of sub-items 39 to 43, wherein the first scanning corrector comprises at least one correcting electrode configured to contribute during use to The inhomogeneous electrostatic field distribution generated in the intersecting body (189) of the converging multi-beam deflection system (110) reduces incidence at the intersection at an inclination angle β deviating from the optical axis of the multi-beam charged particle microscope (1) Aberrations caused by individual beamlet scans on the volume (189).

Subitem 50: A method of operating a multi-beam charged particle microscope (1), comprising the steps of: Generate a scanning voltage difference VSp(t); providing the scanning voltage difference VSp(t) to the convergent multi-beam raster scanner (110), so as to use the convergent multi-beam raster scanner (110) to converge deflection scan a plurality of primary beamlets in a first direction (3); generating at least a first scanning correction voltage difference VCp(t) from the scanning voltage difference VSp(t), which is synchronized with the scanning voltage difference VSp(t); providing the first scan correction voltage difference VCp(t) to a deflection element of a scan corrector to reduce aberrations caused by scanning of at least one individual beamlet of the plurality of primary beamlets (3) .

Sub-item 51: The operation method of the multi-beam charged particle microscope (1) as described in sub-item 50, which further includes providing a plurality of static control signals to the scan calibrator to generate the first scan calibration voltage difference VCp(t ) steps.

Sub-item 52: The multi-beam charged particle microscope (1) operation method as described in sub-item 50 or 51, which further includes between the first scanning correction voltage difference VCp(t) and the scanning voltage difference VSp(t). A step of generating a predetermined time delay between the converged raster scans of the plurality of primary beamlets (3) and reducing aberrations caused by the scanning of the at least one individual beamlet.

Sub-item 53: A multi-beam charged particle microscope (1, 1001) for wafer inspection, comprising: a beamlet generator for generating at least a first primary charged particle beamlet (3.0, 3.1, 3.2); An object irradiation unit (100) for irradiating an image field of a sample surface (25) arranged in an object plane (101) with the first primary charged particle beamlet (3.0, 3.1, 3.2); A raster scanner (110) comprising at least a first set of deflection electrodes (153) and an intersecting body (189) through which the first primary charged particle beamlets (3.0, 3.1, 3.2) pass (189); a control unit (800) configured to provide during use at least a first scanning voltage difference VSp(t) to the first set of deflection electrodes (153) for the first or p direction on the image field Scanning deflection of the first charged particle beamlet (3.0, 3.1, 3.2), the lateral extension of the image field is at least 5 μm, preferably 8 μm or more; at least one first scan rectifier (601, 185, 193) configured, during use, to generate a first scan rectification field for influencing the first primary charged particle beamlet (3.0, 3.1, 3.2), Wherein the control unit (800) is further configured to provide individual first scan voltage differences VSp(t) to the first scan correctors (601, 185, 193), the first scan correctors (601, 185, 193 ) reduces the aberrations caused by the scanning of the first primary charged particle beamlet (3.0, 3.1, 3.2) synchronized with the scanning deflection of the first primary charged particle beamlet (3.0, 3.1, 3.2).

Sub-item 54: The multi-beam charged particle microscope (1) of sub-item 53, wherein the first scan corrector (601, 185, 193) comprises a first electrostatic voltage conversion unit for the first The scan voltage difference VSp(t) is converted into at least one first scan correction voltage difference VCp(t) adapted to generate the first scan correction field synchronously with the first scan voltage difference VSp(t).

Sub-item 55: The multi-beam charged particle microscope (1) according to sub-item 54, wherein the static voltage conversion unit comprises at least one programmable resistor series configured to be programmed by a plurality of static control signals.

Sub-item 56: The multi-beam charged particle microscope (1) as described in sub-item 54 or 55, wherein the static voltage conversion unit generates the first scan correction voltage proportional to the first scan voltage difference VSp(t) Difference VCp(t).

Sub-item 57: The multi-beam charged particle microscope (1) according to any one of sub-items 53 to 56, wherein the control unit (800) further comprises a first delay line which makes the first scan corrector The field is synchronized with the raster scanning of the first primary charged particle beamlets (3.0, 3.1, 3.2) by the raster scanner (110).

Sub-item 58: The multi-beam charged particle microscope (1) according to any one of sub-items 53 to 57, wherein the first scan corrector (601, 185, 193) comprises at least one first deflection element, the During use of the first deflection element, the aberrations caused by the scanning of the first primary charged particle beamlet (3.0, 3.1, 3.2) from about 0.5 nm to 5 nm are compensated to below 0.3 nm, preferably below A reduction of 0.2 nm or less than 0.1 nm.

Sub-item 59: The multi-beam charged particle microscope (1) as described in sub-item 58, wherein the scanning-induced aberration is scanning-induced distortion.

Sub-item 60: The multi-beam charged particle microscope (1) of sub-item 58 or 59, wherein the first deflection element is configured to individually compensate the first primary charged particle beamlets (3.0, 3.1 , 3.2) the distortion caused by scanning along the first direction, which is related to the first primary charged particle beamlet (3.0, 3.1, 3.2) Scan deflection synchronization.

Sub-item 61: A multi-beam charged particle microscope (1) according to sub-item 60, further comprising a second deflection element configured to individually compensate the first primary charged particle beamlets (3.0, 3.1, 3.2) The distortion caused by scanning along the second direction is smaller than that of the first primary charged particles in the first direction perpendicular to the second direction by the raster scanner (110) Scanning deflection synchronization of the beams (3.0, 3.1, 3.2).

Sub-item 62: The multi-beam charged particle microscope (1) as described in sub-item 58, wherein the scanning-induced aberration is at least scanning-induced distortion, scanning-induced astigmatism, scanning-induced telecentric aberration, One of the groups of scanning-induced spherical aberration or scanning-induced hairline aberration.

Sub-item 63: The multi-beam charged particle microscope (1) according to any one of sub-items 53 to 62, further comprising a beamlet generator for generating at least one second primary charged particle Beam (3.1 or 3.2).

Sub-item 64: The multi-beam charged particle microscope (1) of sub-item 63, wherein the first scan corrector further comprises a third deflection element which individually compensates the second primary charged particle size during use aberrations caused by the scanning of the beam (3.1 or 3.2).

Sub-item 65: The multi-beam charged particle microscope (1) of sub-item 64, wherein the static voltage conversion unit comprises at least one first programmable resistor series connected to the first deflection element and Controlled by a plurality of static control signals, a scanning correction voltage difference VCAp(t) synchronous with the first scanning voltage difference VSp(t) is generated during use.

Sub-item 66: The multi-beam charged particle microscope (1) of any one of sub-items 53 to 65, further comprising a second scan corrector (602, 187, 195) for During raster scanning of at least a first primary charged particle beamlet (3.0, 3.1, 3.2) by the scanner (110), aberrations induced by the second scanning are reduced.

Sub-item 67: A multi-beam charged particle microscope (1) for wafer inspection, comprising: A multi-beamlet generator (300), used to generate a plurality of primary beamlets (3), including at least a first primary beamlet and a second primary beamlet; An object illumination unit (100) for illuminating an image patch (17) of a wafer surface (25) arranged in an object plane (101), thereby generating during use a plurality of secondary electron beamlet (9); a converging multi-beam raster scanner (110) forming an intersecting volume (189) for performing converging raster scanning of a plurality of primary beamlets (3) to form an image scan of the image block (17), which comprising at least the first primary beamlet (3.55) scanned over a first image subfield (31.55) and simultaneously scanned over a second image subfield (31.15) of the image tile (17) The second primary beamlet (3.15); A detection unit (200), which has a projection system (205) and an image sensor (207), for imaging a plurality of small secondary electron beams (9) on the image sensor (207) and used to acquire a digital image during image scanning; a first scan corrector (601) connected to the control unit (800) and reducing the first primary beamlet (3.55) in the first image subfield (31.55) and the The distortion difference caused by scanning between the second primary beamlets (3.15) in the second image subfield (31.55).

Sub-item 68: The multi-beam charged particle microscope (1) of sub-item 67, wherein the first scan corrector (601) generates, during use, a plurality of scanning electrostatics for affecting the plurality of primary beamlets Fields comprising a first scanning electrostatic field for influencing the first primary beamlet (3.55) and a second scanning electrostatic field for independently influencing the second primary beamlet (3.15).

Sub-item 69: The multi-beam charged particle microscope (1) of sub-item 68, wherein the first scan corrector (601) comprises a plurality of deflection elements including a first deflection element and a second deflection element , which during use compensates for distortions caused by the plurality of scans of each of the plurality of primary beamlets (3), including a first scan of the first primary beamlet (3.55) and the distortion caused by a second scan of the second primary beamlet (3.15).

Sub-item 70: The multi-beam charged particle microscope (1) of any one of sub-items 68 to 69, wherein the control unit (800) provides a first scanning voltage difference VSp(t) to the A converging multi-beam raster scanner (110), wherein the first scan corrector (601) includes a scan array control unit (622) for converting the first scan voltage difference VSp(t) into a plurality of scan correctors The voltage difference VCAp(i,t) is adapted to generate, during use, a plurality of electrostatic fields synchronized with the first scanning voltage difference VSp(t).

Sub-item 71: The multi-beam charged particle microscope (1) as described in sub-item 70, wherein the scanning array control unit (622) comprises a plurality of electrostatic voltage conversion units (611, 612), which during use are from the first A scanning voltage difference VSp(t) generates the plurality of scanning correction voltage differences VCAp(i,t).

Sub-item 72: The multi-beam charged particle microscope (1) as described in sub-item 71, wherein each of the plurality of electrostatic voltage conversion units (611, 612) is configured as a programmable resistance series, which is configured as Controlled by a plurality of static control signals.

Sub-item 73: The multi-beam charged particle microscope (1) according to any one of sub-items 68 to 72, wherein the control unit (800) further comprises a first delay line which makes the first scan corrector (601) The scanning electrostatic field is synchronized with the convergent raster scanning of the plurality of primary beamlets (3) by the convergent multi-beam raster scanner (110).

Sub-item 74: The multi-beam charged particle microscope (1) of any one of sub-items 69 to 73, wherein the first deflection element is configured to individually compensate the first primary beamlets (3.55 ) distortion caused by scanning along a first direction, which is synchronized with scanning deflection of the plurality of primary beamlets (3) in the first direction by the converging multi-beam raster scanner (110).

Sub-item 75: The multi-beam charged particle microscope (1) of sub-item 74, wherein the first deflection element is further configured to individually compensate the first primary beamlets (3.55) during use along the second The distortion caused by the scanning in the direction, which is related to the scanning deflection of the plurality of primary beamlets (3) in the first direction perpendicular to the second direction by the converging multi-beam raster scanner (110) Synchronize.

Sub-item 76: The multi-beam charged particle microscope (1) of sub-item 74 or 75, wherein the second deflection element is configured to individually compensate the second primary beamlets along the first direction during use The distortion caused by the scanning of the convergent multi-beam raster scanner (110) is synchronized with the scanning deflection of the plurality of primary beamlets (3) in the first direction.

Sub-item 77: The multi-beam charged particle microscope (1) of sub-item 67 to 76, wherein during use the first primary beamlet passes through the intersecting body (189) at a first angle β1, And the second primary beamlet passes through the intersecting volume (189) at a second angle β2 different from the first angle β1.

Sub-item 78: The multi-beam charged particle microscope (1) as described in sub-items 67 to 77, further comprising a second scan corrector (602) connected to a control unit (800) and during image scanning , reducing the distance between the first primary beamlet (3.55) in the first image subfield (31.55) and the second primary beamlet (3.15) in the second image subfield (31.55) The telecentric difference caused by the scan.

Sub-item 79: A method of operating a multi-beam charged particle microscope (1), comprising the steps of: Generate a scanning voltage difference VSp(t); providing the scanning voltage difference VSp(t) to the convergent multi-beam raster scanner (110), so as to use the convergent multi-beam raster scanner (110) to converge deflection scan a plurality of primary beamlets in a first direction (3); Generate a plurality of scanning correction voltage differences VCAp(i,t) from the scanning voltage difference VSp(t) through a plurality of electrostatic voltage conversion units, which are synchronized with the scanning voltage difference VSp(t); A plurality of scan correction voltage differences VCAp(i,t) are provided to deflection elements of the scan corrector to reduce distortions caused by the scans of the plurality of primary beamlets (3).

Sub-item 80: The operation method of the multi-beam charged particle microscope (1) as described in sub-item 79, which further includes providing a plurality of static control signals to the plurality of static voltage conversion units to generate the plurality of scanning correction voltage differences Steps of VCAp(i,t).

Sub-item 81: The multi-beam charged particle microscope (1) operating method as described in any one of sub-items 79 or 80, which further includes the difference between the plurality of scanning correction voltage differences VCAp(i,t) and the scanning voltage A predetermined time delay is created between the differences VSp(t) to synchronize the convergent raster scanning of the plurality of primary beamlets (3) and to reduce scanning-induced distortion steps.

Sub-item 82: The operation method of the multi-beam charged particle microscope (1) as described in sub-item 79, which further includes the following steps: Determining the distortion caused by fixed scanning by scanning a plurality of primary charged particles on an image patch of a reference object; extracting a plurality of amplitudes of at least a linear portion of the distortion induced by each scan of the charged particle beamlet; - Deriving a plurality of static control signals from each of the plurality of amplitudes.

Sub-item 83: A multi-beam charged particle beam microscope (1) for wafer inspection, comprising: a first long-stroke raster scanner (110) for performing raster scanning of a plurality of primary charged particle beamlets (3), comprising at least one first primary beamlet (3.0, 3.1, 3.2), and Convergent scanning deflects each of the plurality of primary charged particle beamlets (3) within a scan range extending D = 5 μm to 12 μm corresponding to an image subfield (31) on a wafer surface (25) By; a second short-stroke raster scanner (601) configured to individually correct aberrations induced by scanning of each primary charged particle beamlet comprising the first primary beamlet (3.0, 3.1, 3.2), the scan-induced aberrations are introduced during convergent scan deflection of the first long-stroke raster scanner (110); A control unit (800) configured to synchronize the scanning deflection of the first long-stroke raster scanner (110) with the second short-stroke raster scanner (601) to correct aberrations caused by individual scanning.

Sub-item 84: The multi-beam charged particle microscope (1) of sub-item 83, wherein the scanning-induced aberration is scanning distortion, and wherein the second short-stroke raster scanner (601 ) corresponds to a Scanning deflects each primary beamlet within the scanning range of maximum scanning distortion rm, where |rm| < D/1000.

Sub-item 85: The multi-beam charged particle microscope (1) of sub-item 83 or 84, wherein the charged particle beam microscope (1) comprises a third short-stroke raster scanner (602) for scanning the The telecentric aberration caused by scanning is corrected, which corrects the telecentric aberration caused by the scanning introduced during the scanning deflection of the plurality of primary beamlets (3) of the first long-stroke raster scanner (110), and wherein the control The unit (800) combines the scanning deflection of the plurality of primary beamlets with the first long-stroke raster scanner (602) with the first long-stroke raster scanner (110) and with the second short-stroke raster scanner (601) Scan correction synchronization for aberrations induced by the scan.

Sub-item 86: The multi-beam charged particle microscope (1) according to any one of sub-items 83 to 85, further comprising at least one scanning array control unit (622), which is used to apply a scanning voltage difference VSp( t) is converted into a plurality of scanning correction voltage differences VCap(i,t), so as to perform scanning correction of aberrations caused by scanning.

Sub-item 87: The multi-beam charged particle microscope (1) as described in sub-item 86, wherein the scanning array control unit (622) comprises a plurality of electrostatic voltage conversion units (611, 612), which during use from the first A scanning voltage difference VSp(t) generates the plurality of scanning correction voltage differences VCAp(i,t).

Sub-item 88: The multi-beam charged particle microscope (1) as described in sub-item 87, wherein each of the plurality of electrostatic voltage conversion units (611, 612) is configured as a programmable resistor series configured to Controlled by a plurality of static control signals.

Sub-item 89: The multi-beam charged particle microscope (1) according to any one of sub-items 83 to 88, further comprising a beamlet generator (300) for generating a plurality of primary beamlets (3 ); and an object irradiation unit (100) for illuminating a plurality of image tiles (17) of the surface (25) of the object (7) arranged in the object plane (101), thereby generating during use from the surface ( 25) A plurality of secondary electron beamlets (9) emitted.

Sub-item 90: The multi-beam charged particle microscope (1) of sub-item 89, wherein the beamlet generator (300) is configured to generate at least a second primary beamlet, and the first A long-stroke raster scanner (110) collectively scans deflects each of the at least one first and second primary beamlets over a scan range corresponding to an image subfield extension D on the wafer surface, and wherein the The second short-stroke raster scanner (601) is configured to individually correct for aberrations induced by scanning of the first and second primary beamlets.

Sub-item 91: The multi-beam charged particle microscope (1) according to any one of sub-items 83 to 90, further comprising a detection unit (200) having a projection system (205) and an image sensor A detector (207) is used to image the plurality of small secondary electron beams (9) on the image sensor (207) and to obtain a digital image during image scanning.

It will be clear from the description that combinations and various modifications of various examples and embodiments are possible, and can be applied similarly to various examples and examples. The primary beam charged particles may eg be electrons, but also other charged particles such as helium ions. Secondary electrons include these and electrons in the narrow sense, but also include any other secondary charged particles produced by the interaction of a primary charged particle beamlet with a sample, such as backscattered electrons or secondary electrons produced by backscattered electrons. secondary electrons. In another example, secondary ions may be collected instead of secondary electrons.

1: Multi-beamlet charged particle microscope system 3: A small beam of primary charged particles, forming a plurality of small beams of primary charged particles 5: Primary charged particle beam spot 7: Object 9: Secondary electron beamlets, forming multiple secondary electron beamlets 11: Secondary electron beam path 13: primary beam path 15:Secondary Charged Particle Spots 17:Image block 19: Overlapping area of image tiles 21: The center position of the image block 25: Wafer surface 27: Scanning path of a small beam 29: The center of the image subfield 31: Image subfield 33: The first detection part 35: The second detection part 39: Overlapping area of subfield 31 100: object irradiation unit 101: Object plane or image plane 102: objective lens 103: field lens group 105:Optical axis of multi-beamlet charged particle microscope system 108: First Beam Intersection 110: The first multi-beam raster scanner 112: Correction elements for multi-beam raster scanners 120:Scan correction control module 141:Example of primary beam spot position 143: Static displacement vector of primary beam spot 150: center small beam 151:Real Beamlet Orbit 153: deflector electrode 155: Equipotential lines of electrostatic potential 157: Off-axis or field beamlets 159:Virtual Shared Pivot Point 161:Virtual pivot point 163: First order beam path 171: Scanner 110 in front of the system 173: Linear curve 175: Voltage difference as a function of deflection angle 177: The voltage difference as a function of the deflection angle is applied to the deflection electrodes consisting of electrode pairs 179: The offset voltage as a function of the deflection angle is applied to the deflection electrodes consisting of electrode pairs 181: a deflection electrode deflected along a first direction 183: the deflection electrode deflected along the second direction 185: The first set of calibration electrodes 187: The second set of calibration electrodes 189: Intersecting bodies of traveling bundles 190: Internal area of intersecting volumes 191: Asymmetric direction 193: The first set of calibration electrodes 195: The second set of calibration electrodes 197: Lines illustrating linear dependence 200: detection unit 205:Projection system 206: Electrostatic lens 207: Image sensor 208: Imaging lens 209: Imaging lens 210: imaging lens 212:Second Intersection 214: Aperture filter 216: Active components 218: The third deflection yoke 220: Porous corrector 222: Second deflection yoke 300: Charged Particle Multiple Beamlet Generator 301: Charged particle source 303: collimating lens 305: Multiple beamlet forming unit at once 306: active porous plate 307: The first lens 308: second field lens 309: electron beam 311: Primary electron beamlet spot 321: intermediate image plane 390: Beam steering perforated plate 400: beam splitter unit 420: Magnetic components 500: sample carrier 503: sample voltage supply 601: First scan corrector or scan distortion compensator array 602: Second scan corrector or scan compensator array for telecentric aberration 607: conductive thread 609: The first power cord 610: Second power cord 611: the first voltage conversion unit 612: the second voltage conversion unit 613: The first multiple conductive lines 614: second plurality of conductive lines 615: the first plurality of control signals 616: the second plurality of control signals 618: Connect the signal line 620: perforated plate 622:Scan array control module 624: clock line 626: Operation control memory 631: data or voltage connection line 633: Resistance sequence 635: The first group of control signals 637: The second group of control signals 639: Transistor sequence 641:Voltage combiner 681: electrode 685: hole or multiple holes 687: Electrode Deflected Along a First Direction 688: Electrode Deflected Along Second Direction 701: The first static multi-beam deflection system 703: Second static multi-beam deflection system 800: control unit 810: image data acquisition unit 812: Image splicing unit 814: Image data output 820:Projection system control module 830: primary beam path control module 840: Control Operations Processor 860: Scan deflection control module 862: delay line array 870: Static adjustment control module

More details will be disclosed below with reference to the accompanying drawings. It shows: FIG. 1 is a diagram of a multi-beam charged particle microscope system according to an embodiment. FIG. 2 is a diagram including the coordinates of the first detection location and the second detection location of the first and second image blocks. Fig. 3 is a static distortion offset diagram of a plurality of primary charged particle beamlets (3). Figure 4 is a scan deflection diagram at the scan deflector, (a) for on-axis beamlets and (b) distortion induced by scanning for off-axis beamlets with propagation angle β. FIG. 5 is a diagram of telecentric aberrations induced by scanning of off-axis beamlets with propagation angle β. Figure 6 is a diagram of the distortion induced by a typical scan of a single beamlet during scanning over an image subfield with image subfield coordinates (p, q); a) scan distortion vectors dp, dq; b) Sweep distortion amplitude. Fig. 7 is a maximum scanning distortion vector diagram of each image sub-field of a plurality of primary charged particle beamlets having center coordinates x _ij , y _ij of the image sub-field. 8 is two exemplary diagrams of deflection electrodes and correction electrodes of a convergent multi-beam raster scanner for generating a non-uniform electrostatic deflection field within an intersecting volume of multiple primary charged particle beamlets. Figure 9 shows the voltage difference for scanning deflection depending on the scanning angle α; a) for a single deflection electrode; b) for a deflection electrode constructed from two separate electrodes. 10 is a schematic diagram of deflection electrodes and correction electrodes of a converging multi-beam raster scanner arranged in the propagation direction for generating a non-uniform electrostatic deflection field inside a plurality of intersecting volumes of primary charged particle beamlets. Figure 11 is a diagram of deflection electrodes of different lengths for generating a non-uniform electrostatic deflection field within an intersecting volume of multiple primary charged particle beamlets. FIG. 12 is a diagram of a plurality of deflection elements arranged at a plurality of apertures of a multi-beam scanning distortion compensator array or a telecentric aberration scanning compensator array. FIG. 13 is a diagram of a scanning array control unit taking the scanning distortion compensator array as an example. FIG. 14 is a diagram of a programmable resistor array taking the static voltage conversion unit as an example. FIG. 15 is an example of driving signals taking the scanning voltage difference as an example. 16 is a schematic diagram of a method of operation of a multi-beam charged particle microscope with reduced scanning-induced aberrations. Figures 17a-h are typical field correlations over image patch coordinates (x,y) for four linear distortion vectors SDV(i) and their relationship in image subfields with subfield coordinates (p,q). characteristic schema. Figure 18 is a diagram of a multi-beam charged particle microscope including additional first and second static multi-beam deflection systems for adjustment. Figure 19 is a typical field dependence of distortion aberrations on image tile coordinates (x,y) for a scan with a misaligned system. Fig. 20 is a multi-beam charged particle microscope according to an eighth embodiment of the present invention. Figure 21 is an example of a scanning correction electrode with a tilt angle relative to the optical axis for generating a non-uniform electrostatic deflection field in an intersecting volume of multiple primary charged particle beamlets.

1: Multi-beamlet charged particle microscope system

100: object irradiation unit

110: The first multi-beam raster scanner

112: Correction elements for multi-beam raster scanners

120:Scan correction control module

200: detection unit

207: Image sensor

222: Second deflection yoke

300: Charged Particle Multiple Beamlet Generator

500: sample carrier

601: First scan corrector or scan distortion compensator array

602: Second scan corrector or scan compensator array for telecentric aberration

701: The first static multi-beam deflection system

703: Second static multi-beam deflection system

800: control unit

810: image data acquisition unit

812: Image splicing unit

814: Image data output

830: primary beam path control module

840: Control Operations Processor

860: Scan deflection control module

862: delay line array

Claims (64)

A multi-beam charged particle microscope (1) for wafer inspection comprising: Charged particle multi-beamlet generator (300), used to generate a plurality of primary charged particle beamlets (3); An object irradiation unit (100) for irradiating an image block (17.1) arranged on a surface (25) of an object (7) in an object plane (101) by means of the plurality of primary charged particle beamlets (3) ), thereby generating a plurality of secondary electron beamlets (9) emitted from the surface (25) during use; A detection unit (200), which has a projection system (205) and an image sensor (207), for imaging the plurality of small secondary electron beams (9) on the image sensor (207 ) and for acquiring a digital image of the image tile (17.1) of the surface (25) during use; a converging multi-beam raster scanner (110); A scanning distortion compensator array (601) having a plurality of apertures arranged upstream of the converging multi-beam raster scanner (110) in the propagation direction of the plurality of primary charged particle beamlets, between the plurality of apertures Each transmits a corresponding one of the plurality of primary charged particle beamlets (3) during use (3.0, 3.1, 3.2), each of the plurality of apertures comprising a first deflection element for individually deflecting each respective primary charged particle beamlet (3.0, 3.1, 3.2) in the first or p direction; and each of the plurality of apertures comprises a second deflection element for individually deflecting each respective primary charged particle beamlet (3.0, 3.1, 3.2) in a second or q direction perpendicular to the first direction; a control unit (800) which, during use, provides at least a first scanning voltage difference VSp(t) to the converging multi-beam raster scanner (110) to scan deflect the complex a primary charged particle beamlet (3), Wherein the scanning distortion compensator array (601) further includes a scanning array control unit (622), which has a first electrostatic voltage conversion array (611), which is configured to provide a plurality of first correction voltage differences to the plurality of a first deflection element; and a second electrostatic voltage conversion array (612), which is configured to provide a plurality of second correction voltage differences to the plurality of second deflection elements to compensate the plurality of primary charged particle beamlets ( 3) Aberrations caused by scanning during scanning deflection in the first direction. The multi-beam charged particle microscope (1) for wafer inspection according to claim 1, wherein the first static voltage conversion array (611) is coupled to the control unit (800), and will communicate with the first At least a plurality of first voltage difference components synchronized with the scanning voltage difference VSp(t) are supplied to each of the plurality of first and second deflection elements. The multi-beam charged particle microscope (1) according to claim 1 or 2, wherein the control unit (800) provides a second scanning voltage difference VSq(t) to the converging multi-beam raster scanner during use (110), for scanning and deflecting the plurality of primary charged particle beamlets (3) in the second or q direction. The multi-beam charged particle microscope (1) for wafer inspection according to claim 3, wherein the first static voltage conversion array (611) and the second static voltage conversion array (612) are coupled to the control unit (800), and provide at least a plurality of second voltage differential components synchronized with the second scanning voltage difference VSq(t) to each of the plurality of first and second deflection elements. The multi-beam charged particle microscope (1) for wafer inspection according to claim 3 or 4, wherein the first static voltage conversion array (611) is coupled to the control unit (800), and at least communicates with A first voltage difference component synchronized with the first scan voltage difference VSp(t) and a second voltage difference component synchronized with the second scan voltage difference VSq(t) are supplied to each of the plurality of first deflection elements . The multi-beam charged particle microscope (1) according to any one of claims 1 to 5, wherein the first or second static voltage conversion array (611, 612) is configured as a programmable resistor array. The multi-beam charged particle microscope (1) according to any one of claims 1 to 6, wherein the convergent multi-beam raster scanner (110) comprises at least a first set of deflection electrodes and an intersecting body (189) , the plurality of primary charged particle beamlets (3) pass through the intersecting volume (189), wherein the converging multi-beam raster scanner (110) generates a predetermined non-uniform scanning deflection field in the intersecting volume (189) distribution to reduce aberrations caused by scanning a primary charged particle beamlet incident on the intersecting body (189) at an inclination angle off the optical axis of the multi-beam charged particle microscope (1). The multi-beam charged particle microscope (1) as claimed in claim 7, wherein a deflection electrode of the first set of deflection electrodes consists of two spaced apart electrodes, and the control unit (800) provides the first set of deflection electrodes during use A scanning voltage difference VSp1(t) and the second scanning voltage difference VSp2(t) are applied to the two spaced apart electrodes, wherein the first scanning voltage difference VSp1(t) and the second scanning voltage difference VSp2(t) different. A multi-beam charged particle microscope (1) as claimed in claim 7 or 8, wherein the converging multi-beam scanning raster scanner (110) comprises a second set of deflection electrodes for generating a second predetermined non-uniform scanning deflection field distribution, the plurality of primary charged particle beamlets (3) pass through a second predetermined non-uniform scanning deflection field distribution in the intersection volume (189) to scan in the second or q direction The plurality of primary charged particle beamlets are deflected (3). The multi-beam charged particle microscope (1) of claim 9, wherein the shape and geometry of the at least one first or second set of deflection electrodes of the converging multi-beam raster scanner (110) are adapted to the Cross section of intersecting body (189). The multi-beam charged particle microscope (1) as claimed in claim 9 or 10, wherein in the average propagation direction of the plurality of primary charged particle beamlets (3), the first set of deflection electrodes and the second set The deflection electrodes have different lengths. The multi-beam charged particle microscope (1) according to any one of claims 7 to 11, wherein the convergent multi-beam raster scanner (110) further comprises a first set of correction electrodes (185, 193), which A predetermined scanning correction field is generated during use that contributes to the predetermined non-uniform electrostatic field distribution. The multi-beam charged particle microscope (1) according to claim 12, wherein the electrodes (185.1, 185.2, 185.3, 185.4) of the first set of correction electrodes are arranged between one electrode of the first set of deflection electrodes and the second In the space between electrodes of a set of deflection electrodes. The multi-beam charged particle microscope (1) according to any one of claims 11 or 12, wherein the converging multi-beam raster scanner (110) further comprises a second set of correction electrodes (187, 195), which A predetermined second scan correction field is generated during use that contributes to the predetermined non-uniform electrostatic field distribution. The multi-beam charged particle microscope (1) according to any one of claims 1 to 14, wherein the converging multi-beam raster scanner (110) adjusts the predetermined non-uniform scanning deflection field distribution relative to the intersecting volume lateral position, and the control unit (800) provides a voltage offset to at least one of the first set of deflecting electrodes or the second set of deflecting electrodes during use. The multi-beam charged particle microscope (1) according to any one of claims 1 to 15, further comprising the charged particle multi-beamlet generator (300) and the converging multi-beam raster scanner ( 110) between a first static deflection system (701), which is used to adjust the lateral position of the plurality of primary charged particle beamlets (3) relative to the intersection body (189). The multi-beam charged particle microscope (1) according to any one of claims 1 to 16, further comprising the charged particle multi-beamlet generator (300) and the converging multi-beam raster scanner ( 110) between a second static deflection system (701), which is used to adjust the average incident angle of the plurality of primary charged particle beamlets (3) on the entrance of the intersecting body (189). The multi-beam charged particle microscope (1) according to any one of claims 1 to 17, further comprising a scanning compensator array (602) for compensating the telecentric aberration caused by scanning, which is arranged in the Near the intermediate image plane (321) of the multi-beam charged particle microscope (1), the scanning compensator array (602) has a plurality of deflection elements arranged on a plurality of apertures; and one of the second static voltage conversion arrays The second scanning array control unit (622.2), configured to provide a plurality of second correction voltage differences to each of the plurality of deflection elements to compensate for scanning the primary charged particle beamlets (3 ) The telecentric aberration caused by each. The multi-beam charged particle microscope (1) according to any one of claims 1 to 18, further comprising another array of scanning compensators for compensating aberrations caused by scanning, such as the plurality of primary charged Astigmatism or focal plane deviation caused by the scanning of each of the particle beamlets (3). A method for operating a multi-beam charged particle microscope (1), the microscope has a charged particle multi-beam generator (300), an object irradiation unit (100), a detection unit (200), a A convergent multi-beam raster scanner (110) for performing convergent raster scanning on a plurality of small primary charged particle beams (3), and a convergent multi-beam raster scanner arranged in the propagating direction of the plurality of small primary charged particle beams (110) upstream scanning distortion compensator array (601), and a control unit (800), which includes the following steps: providing at least a first scanning voltage difference VSp(t) to a scanning array control unit (622); generating a plurality of voltage differential components from at least the first voltage difference VSp(t) and a plurality of static control signals (635); The plurality of voltage differential components are provided to the plurality of deflection elements of the scanning distortion compensator array (601) to individually scan and deflect each beamlet (3.0, 3.1) of the plurality of primary charged particle beamlets (3) , 3.2) to compensate for the distortion caused by the plurality of scans during the scan deflection of the plurality of primary charged particle beamlets (3). The operation method of the multi-beam charged particle microscope (1) as described in claim 20, which further includes the following steps: Determining the distortion caused by scanning by scanning the plurality of primary charged particles (3) on an image patch (17) of a reference object; extracting amplitudes of at least one linear portion of each of the distortions induced by the plurality of scans of each primary charged particle beamlet (3.0, 3.1, 3.2); deriving a plurality of control signals from each of the plurality of amplitudes (635); The plurality of control signals (635) are provided to the scanning array control unit (622) of the scanning distortion compensator array (601). A multi-beam microscope (1) for wafer inspection comprising: A multi-beamlet generator (300) for generating a plurality of primary beamlets (3), including at least one first individual beamlet; An object irradiation unit (100), configured to irradiate an image block (17.1) arranged on the surface (25) of the object (7) in the object plane (101) through the plurality of primary beamlets (3), thereby generating a plurality of secondary electron beamlets (9) emanating from the surface (25) during use; A detection unit (200), which has a projection system (205) and an image sensor (207), for imaging the plurality of small secondary electron beams (9) on the image sensor (207 ) and for acquiring a digital image of the image tile (17.1) on the surface (25) during use; a converging multibeam raster scanner (110) comprising at least a first set of deflection electrodes and an intersecting body (189) through which the plurality of primary beamlets (3) pass; at least one first scan corrector configured, during use, to generate a first scan electrostatic field to affect at least the first individual beamlet; a control unit (800) configured to provide, during use, at least a first scanning voltage difference VSp(t) to the first set of deflection electrodes for collectively raster scanning the plurality of once in the first or p direction beamlet(3), Wherein the control unit (800) further provides the first scan voltage difference VSp(t) to the first scan corrector, and the first scan corrector reduces aberrations caused by scanning of at least the first individual beamlet. The multi-beam charged particle microscope (1) as claimed in claim 22, wherein the first scan corrector includes a first static voltage conversion unit for converting the first scan voltage difference VSp(t) into at least one The first scanning correction voltage difference VCp(t) is adapted to generate the first scanning electrostatic field synchronously with the first scanning voltage difference VSp(t). The multi-beam charged particle microscope (1) according to claim 23, wherein the static voltage conversion unit comprises at least one programmable resistor series configured to be programmed by a plurality of static control signals (635). The multi-beam charged particle microscope (1) as claimed in claim 22 or 23, wherein the first static voltage conversion unit generates the first scanning correction voltage difference VCp proportional to the first scanning voltage difference VSp(t) (t). The multi-beam charged particle microscope (1) according to any one of claims 22 to 25, wherein the control unit (800) further comprises a first delay line, which makes the first scan corrector field and by The converging multi-beam raster scanner (110) synchronizes the converging raster scanning of the plurality of primary beamlets (3). A multi-beam charged particle microscope (1) as claimed in any one of claims 22 to 26, wherein the first scan corrector comprises a plurality of deflection elements configured to compensate, during use, a plurality of primary small The distortion caused by the scanning of each beamlet in beam (3). A multi-beam charged particle microscope (1) as claimed in claim 27, wherein the plurality of deflection elements comprise a first deflection element which during use individually compensates the first individual beamlets along the first direction The distortion caused by the scanning of the convergent multi-beam raster scanner (110) is synchronized with the scanning deflection of the plurality of primary beamlets (3) in the first direction. The multi-beam charged particle microscope (1) according to claim 28, wherein the plurality of deflection elements further comprise a second deflection element which individually compensates the first individual beamlets in the second direction during use The distortion caused by the scanning of the convergent multi-beam raster scanner (110) is synchronized with the scanning deflection of the plurality of primary beamlets (3) in the first direction perpendicular to the second direction. The multi-beam charged particle microscope (1) as claimed in claim 28 or 29, wherein the plurality of deflection elements further comprise a third deflection element which individually compensates the second individual beamlets during use in the first The distortion caused by scanning in one direction is synchronized with the scanning deflection of the plurality of primary beamlets (3) in the first direction by the converging multi-beam raster scanner (110). The multi-beam charged particle microscope (1) as claimed in any one of claims 27 to 30, wherein the static voltage conversion unit comprises a plurality of programmable resistance series, each programmable resistance series is connected to a plurality of deflection elements A deflection element, the plurality of programmable resistance arrays form a programmable resistance array controlled by a plurality of static control signals, which generate a plurality of scanning correction voltage differences VCap(i,t) during use, and each scanning correction voltage The difference is synchronized with the first scan voltage difference VSp(t). A method of operating a multi-beam charged particle microscope (1), comprising the following steps: Generate a scanning voltage difference VSp(t); The scanning voltage difference VSp(t) is provided to a convergent multi-beam raster scanner (110) to converge deflection scan a plurality of primary beamlets in a first direction using the convergent multi-beam raster scanner (110). bundle(3); generating at least a first scanning correction voltage difference VCp(t) from the scanning voltage difference VSp(t), which is synchronized with the scanning voltage difference VSp(t); The first scan correction voltage difference VCp(t) is supplied to a deflection element of a scan corrector to reduce aberrations caused by scanning of at least one individual beamlet of the plurality of primary beamlets (3). The operating method of the multi-beam charged particle microscope (1) as claimed in claim 32, further comprising a step of providing a plurality of static control signals to the scan calibrator to generate the first scan calibration voltage difference VCp(t). The operating method of the multi-beam charged particle microscope (1) as claimed in claim 32 or 33, further comprising generating a predetermined time between the first scanning correction voltage difference VCp(t) and the scanning voltage difference VSp(t) The step of delaying to synchronize the converged raster scans of the plurality of primary beamlets (3) and to reduce aberrations induced by the scanning of the at least one individual beamlet. A multi-beam charged particle microscope (1) for wafer inspection comprising: A beamlet generator (300) for generating a plurality of primary charged particle beamlets comprising at least a first primary charged particle beamlet (3.0, 3.1, 3.2); An object irradiation unit (100), irradiating an image field of a surface (25) of a sample arranged in an object plane (101) with the plurality of primary charged particle beamlets (3); A converging raster scanner (110) comprising at least a first set of deflection electrodes (153) and an intersecting body (189) through which the plurality of primary charged particle beamlets (3) pass ; a control unit (800), which during use provides at least a first scanning voltage difference VSp(t) to the first set of deflection electrodes (153) for the first or p direction on its corresponding image field For scanning deflection of each of a plurality of primary charged particle beamlets (3), the lateral extension of the image field is at least 5 μm, preferably 8 μm or more; at least one first scan rectifier (601, 185, 193) configured to generate, during use, a first scan rectification field for individually influencing the plurality of primary charged particle beamlets (3), Wherein the control unit (800) further provides the first scanning voltage difference VSp(t) to the first scanning corrector (601, 185, 193), and the first scanning corrector (601, 185, 193) reduces and Aberrations caused by scanning of the plurality of primary charged particle beamlets (3) in synchronization with the scanning deflection of each of the plurality of primary charged particle beamlets (3). The multi-beam charged particle microscope (1) as claimed in claim 35, wherein the first scan corrector (601, 185, 193) includes a first static voltage conversion unit for the first scan voltage difference VSp (t) is converted into at least one first scan correction voltage difference VCp(t) adapted to generate the first scan correction field synchronously with the first scan correction voltage difference VSp(t). The multi-beam charged particle microscope (1) as claimed in claim 36, wherein the static voltage conversion unit comprises at least one programmable resistor series configured to be programmed by a plurality of static control signals. The multi-beam charged particle microscope (1) as claimed in claim 36 or 37, wherein the static voltage conversion unit generates the first scanning correction voltage difference VCp(t) proportional to the first scanning voltage difference VSp(t) ). The multi-beam charged particle microscope (1) according to any one of claims 35 to 38, wherein the control unit (800) further comprises a first delay line, which makes the first scan corrector field and by The convergent raster scanner (110) is synchronized to the raster scanning of the first primary charged particle beamlets (3.0, 3.1, 3.2). The multi-beam charged particle microscope (1) according to any one of claims 35 to 39, wherein the first scan corrector (601, 185, 193) comprises at least one first deflection element, the first deflection element The aberrations caused by the scanning of the first primary charged particle beamlet (3.0, 3.1, 3.2) from about 0.5 nm to 5 nm during use are compensated to below 0.3 nm, preferably below 0.2 nm or lower A decrease of 0.1 nm. The multi-beam charged particle microscope (1) as claimed in Claim 40, wherein the aberration caused by scanning is distortion caused by scanning. A multi-beam charged particle microscope (1) as claimed in claim 40 or 41, wherein the first deflection element is configured to individually compensate the first primary charged particle beamlets (3.0, 3.1, 3.2) during use along Distortion caused by scanning in the first direction, which is related to scanning deflection of the first primary charged particle beamlet (3.0, 3.1, 3.2) in the first direction by the raster scanner (110) Synchronize. The multi-beam charged particle microscope (1) according to claim 42, further comprising a second deflection element configured to individually compensate the first primary charged particle beamlets (3.0, 3.1, 3.2) during use ) scanning along the second direction, which is related to the first primary charged particle beamlet ( 3.0, 3.1, 3.2) scan deflection synchronization. The charged particle microscope (1) according to claim 40, wherein the aberration caused by the scanning is distortion caused by a scan, astigmatism caused by a scan, telecentric aberration caused by a scan, spherical surface caused by a scan Aberrations or at least one of a group of scan-induced hair-tail aberrations. The multi-beam charged particle microscope (1, 1001) according to any one of claims 35 to 44, wherein the beamlet generator (300) generates at least one second primary charged particle beamlet (3.1 or 3.2). A multi-beam charged particle microscope (1) as claimed in claim 45, wherein the first scan corrector further comprises a third deflection element which individually compensates the second primary charged particle beamlets (3.1 or 3.2) Aberrations caused by scanning. A multi-beam charged particle microscope (1) as claimed in any one of claims 36 to 46, wherein the electrostatic voltage conversion unit comprises at least one first programmable resistor series connected to the first deflection The device is also controlled by a plurality of static control signals, which generate a scanning calibration voltage difference VCAp(t) synchronously with the first scanning voltage difference VSp(t) during use. The multi-beam charged particle microscope (1) as claimed in any one of claims 35 to 47, further comprising a second scan corrector (602, 187, 195) for scanning in the raster scanner (110 ) reduces aberrations caused by the second scan during the raster scan of the at least one first primary charged particle beamlet (3.0, 3.1, 3.2). A multi-beam charged particle microscope (1) for wafer inspection comprising: A multi-beamlet generator (300), used to generate a plurality of primary beamlets (3), including at least a first primary beamlet and a second primary beamlet; an object illumination unit (100) for illuminating an image patch (17) of a surface (25) of a wafer (7) arranged in the object plane (101) so as to generate, during use, images from the surface (25) A plurality of secondary electron beamlets (9) emitted; a converging multi-beam rasterizer (110) forming an intersecting volume (189) for performing converging rastering of a plurality of primary beamlets (3) to form an image scan of the image tile (17), comprising at least the first primary beamlet (3.55) scanned on a first image subfield (31.55) and synchronized on a second image subfield (31.15) of the image tile (17) The second primary beamlet scanned (3.15); A detection unit (200), which has a projection system (205) and an image sensor (207), for imaging a plurality of small secondary electron beams (9) on the image sensor (207) and used to acquire a digital image during image scanning; a first scan corrector (601) connected to a control unit (800) and reducing the first primary beamlet (3.55) and The distortion difference caused by scanning between the second primary beamlets (3.15) in the second image subfield (31.55). The multi-beam charged particle microscope (1) as claimed in claim 49, wherein the first scan corrector (601) generates a plurality of scanning electrostatic fields for affecting the plurality of primary beamlets during use, comprising A first scanning electrostatic field for influencing the first primary beamlet (3.55) and a second scanning electrostatic field for independently influencing the second primary beamlet (3.15). The multi-beam charged particle microscope (1) according to claim 50, wherein the first scan corrector (601) comprises a plurality of deflection elements, and the plurality of deflection elements includes a first deflection element and a second deflection element , compensating during use the distortion caused by the plurality of scans of each of the plurality of primary beamlets (3) including the distortion of the first primary beamlet (3.55) The distortion caused by the first scan and the distortion caused by the second scan of the second primary beamlet (3.15). The multi-beam charged particle microscope (1) according to any one of claims 49 to 51, wherein the control unit (800) provides a first scanning voltage difference VSp(t) to the converging multi-beam during use A raster scanner (110), wherein the first scan corrector (601) includes a scan array control unit (622), configured to convert the first scan voltage difference VSp(t) into a plurality of scan correction voltage differences VCAp( i,t), adapted to generate, during use, a plurality of electrostatic fields synchronized with the first scanning voltage difference VSp(t). The multi-beam charged particle microscope (1) as claimed in claim 52, wherein the scanning array control unit (622) includes a plurality of electrostatic voltage conversion units (611, 612), which are scanned from the first scanning voltage difference during use VSp(t) generates the plurality of scan correction voltage differences VCAp(i,t). The multi-beam charged particle microscope (1) as described in Claim 53, wherein each of the plurality of static voltage conversion units (611, 612) is configured as a programmable resistance series, which is configured by a plurality of static Control signal control. The multi-beam charged particle microscope (1) according to any one of claims 49 to 54, wherein the control unit (800) further includes a first delay line, which makes the first scan corrector (601) Scanning the electrostatic field is synchronized with the convergent raster scanning of the plurality of primary beamlets (3) by the convergent multi-beam raster scanner (110). The multi-beam charged particle microscope (1) according to any one of claims 51 to 55, wherein the first deflection element is configured to individually compensate the first primary beamlets (3.55) during use along the first Distortion caused by scanning in a direction synchronized with scanning deflection of the plurality of primary beamlets (3) in the first direction by the converging multi-beam raster scanner (110). The multi-beam charged particle microscope (1) as claimed in claim 56, wherein the first deflection element is further configured to individually compensate for the scanning effect of the first primary beamlet (3.55) along the second direction during use The resulting distortion is synchronized with the scanning deflection of the plurality of primary beamlets (3) by the converging multi-beam raster scanner (110) in the first direction perpendicular to the second direction. A multi-beam charged particle microscope (1) as claimed in claim 56 or 57, wherein the second deflection element is configured to individually compensate during use caused by scanning of the second primary beamlets along the first direction The distortion of the plurality of primary beamlets (3) is synchronized with the scanning deflection of the convergent multi-beam raster scanner (110) in the first direction. A multi-beam charged particle microscope (1) as claimed in any one of claims 49 to 58, wherein during use the first primary beamlet passes through the intersecting body (189) at a first angle β1, and The second primary beamlet passes through the intersection volume (189) at a second angle β2 different from the first angle β1. The multi-beam charged particle microscope (1) according to any one of claims 49 to 59, further comprising a second scan corrector (602), which is connected to the control unit (800) and during image scanning, reducing the distance between the first primary beamlet (3.55) in the first image subfield (31.55) and the second primary beamlet (3.15) in the second image subfield (31.55) Telecentricity caused by scanning. A method of operating a multi-beam charged particle microscope (1), comprising the following steps: Generate a scanning voltage difference VSp(t); The scanning voltage difference VSp(t) is provided to a converging multi-beam raster scanner (110), and the converging multi-beam raster scanner (110) converges and deflects and scans a plurality of primary beamlets in a first direction (3); Generate a plurality of scanning correction voltage differences VCAp(i,t) from the scanning voltage difference VSp(t) through a plurality of electrostatic voltage conversion units, which are synchronized with the scanning voltage difference VSp(t); A plurality of scan correction voltage differences VCAp(i,t) are supplied to deflection elements of a scan corrector to reduce distortions caused by the scans of the plurality of primary beamlets (3). The operating method of the multi-beam charged particle microscope (1) as described in Claim 61, further comprising providing a plurality of static control signals to the plurality of static voltage conversion units to generate the plurality of scanning correction voltage differences VCAp(i, t) step. The operation method of the multi-beam charged particle microscope (1) as described in any one of claim 61 or 62, which further includes the scanning correction voltage difference VCAp(i,t) and the scanning voltage difference VSp(t ) to generate a predetermined time delay between the steps of synchronizing the convergent raster scanning of the plurality of primary beamlets (3) and reducing distortion caused by the scanning. The method for operating a multi-beam charged particle microscope (1) as described in claim 62, further comprising the following steps: Determining scanning-induced distortion by scanning a plurality of primary charged particles on an image patch of a reference object; extracting a plurality of amplitudes of at least a linear portion of the distortion induced by each scan of the charged particle beamlet; A plurality of static control signals are derived from each of the plurality of amplitudes.

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