TW202207265A - Source-conversion unit, multi-beam apparatus and method to configure a multi-beam apparatus - Google Patents

Abstract

A new multi-beam apparatus with a total FOV variable in size, orientation and incident angle, is proposed. The new apparatus provides more flexibility to speed the sample observation and enable more samples observable. More specifically, as a yield management tool to inspect and/or review defects on wafers/masks in semiconductor manufacturing industry, the new apparatus provide more possibilities to achieve a high throughput and detect more kinds of defects.

Description

Source conversion unit, multi-beam device and method of configuring multi-beam device

The present invention relates to a device with multiple charged particle beams, and more particularly to a device for simultaneously obtaining images of multiple scanning areas by using multiple charged particle beams. Accordingly, the apparatus provided by the present invention can be used to inspect and/or review wafers or masks in the field of semiconductor manufacturing in a high-resolution and high-throughput manner.

The following description and examples in this section are not admitted as prior art by this application.

In the process of manufacturing semiconductor circuit chips, pattern defects or unacceptable particles (eg, residues) inevitably appear on the surface of the wafer or mask, resulting in a significant drop in yield. Therefore, defects or particles must be detected or re-inspected with yield management tools. In order to meet the ever-increasing demands of wafer performance, smaller patterns and smaller critical feature sizes are employed. Thus, due to the diffraction effect, the traditional yield management tools using beams gradually become incapable, and are gradually replaced by the yield management tools using particle beams. Compared to photon beams, electron beams have shorter wavelengths and thus provide better spatial resolution. At present, the yield management tool using electron beam adopts the principle of single electron beam of Scanning Electron Microscope (SEM), which is known to have the disadvantage that the capability of processing samples cannot cope with mass production. Although increasing the beam current can improve the yield, as the current increases, the Coulomb effect can cause a significant decrease in spatial resolution.

To increase productivity, a better approach is to use multiple electron beams, where each electron beam has a small current. The multiple electron beams form a plurality of probe spots on the observation surface of the sample to be tested, or a probe spot array for short. The plurality of detection points can respectively and simultaneously scan a plurality of small scanning areas within a large observation area on the surface of the sample. The electrons at each detection point hit the surface of the sample and thereby generate secondary electrons. Secondary electrons include slow secondary electrons (energy less than 50 eV) as well as backscatter electrons (energy close to the landing energy of the electron). Secondary electrons reflected from multiple small scanning areas can be collected separately and simultaneously by multiple electron detectors. Thus, multi-electron beam scanning can obtain images of large observation areas with multiple small scanning areas faster than scanning using a single electron beam.

The multiple electron beams can each be from multiple electron sources, or from a single electron source. For a multi-electron source, multiple electron beams are usually focused through individual electron cavities to scan multiple small scanning areas, and the secondary electrons generated from each small scanning area are set in the corresponding Detected by an electronic detector in the electronic cavity. Therefore, such devices are often referred to as multi-electron cavity devices or devices. At the sample surface, the multiple electron beams are spaced from each other on the order of several or tens of millimeters (mm).

For a single electron source, an electron source conversion unit is usually used to convert the single electron source into a plurality of sub-sources. The electron source conversion unit includes a beamlet-limiting or beamlet-forming tool or method having a plurality of beam-limiting openings, and a multi-electron optical element for image forming. tool or method. The plurality of beam-limiting openings divide a primary-electron beam generated by a single electron source into a plurality of sub-beams or beams, respectively. The plurality of electron optical elements affect the plurality of beams to respectively form a plurality of first parallel (virtual or real) images of the single electron source. Each first image is an intersection of a beam and can be seen as a source of secondary electrons emitting the corresponding beam. To increase the amount of beams, the spacing between beams is on the order of micro meters. In addition, a one-shot imaging system and a skew scanning unit disposed in the electron cavity are used to respectively project a plurality of first parallel images and respectively scan the plurality of small scanning areas. The secondary electrons generated from the scanning are guided by a beam splitter to a secondary projection imaging system, and then the secondary projection imaging system focuses the secondary electrons to be respectively collected by a plurality of electron detection devices arranged in a single electron cavity. detected by a detection unit. The plurality of detection units may be a plurality of electronic detectors arranged side by side, or a plurality of pixels of one electronic detector. Due to the above characteristics, the above-mentioned device is often referred to as a multi-electron beam device.

A tool or method for beam confinement, typically a conductive plate having a plurality of perforations that act as beam confinement openings. In the work or method of image formation, each electron optical element focuses a beam to form a real image (such as US Pat. No. 7,244,949 and the fourth application in related applications filed in this case), or a The beam is deflected to form a virtual image (eg, US Pat. No. 7,244,949 and others in the related applications filed here). Figures 1 and 2 show two examples in the fifth related application of the present application. For clarity of presentation, only three beams are shown in the figure, and the skew scanning unit, beam splitter, reprojection imaging system, and electronic detection device are omitted.

As shown in FIG. 1A , the primary electron beam 102 generated by the electron source 101 is focused by the condenser lens 110 and incident on the electron source conversion unit 120 . The electron source conversion unit 120 comprises a pre-beam bending tool 123 with three pre-bending micro-deflectors (123_1, 123_2, 123_3), a beam limiting tool 121 with three beam-limiting openings (121_1, 121_2, 121_3), And the image forming tool 122 of the three electro-optical elements (122_1, 122_2, 122_3). Three pre-bent micro-deflectors (123_1, 123_2, 123_3) deflect the three beams (102_1, 102_2, 102_3) to be orthogonal to the three beam-limiting openings (121_1, 121_2, 121_3), respectively . And each beam-limiting opening ( 121_1 , 121_2 , 121_3 ) acts as a beam-limiting opening to limit the current of the corresponding beam. The three electron optical elements (122_1, 122_2, 122_3) respectively deflect the three beams (102_1, 102_2, 102_3) toward the optical axis 100_1, and form three first virtual images of the electron source 101, that is, Each beam has a virtual crossover. The primary projection imaging system is constituted by the objective lens 131 , which focuses the three deflected beams 102_1 to 3 on the surface 7 of the sample 8 , ie, projects three first virtual images on the surface 7 . Therefore, the three beams 102_1-3 form three detection points (102_1s, 102_2s, 102_3s) on the surface 7 . The current of the detection point (102_1s, 102_2s, 102_3s) can be changed by adjusting the power of the condenser lens 110 . As shown in FIG. 1B , the movable condenser lens 210 focuses the primary electron beam 102 so that its normal line is incident on the beam limiting tool 121 of the electron source conversion unit 220 , so the pre-beam bending tool 123 as shown in FIG. 1A is not required. . Therefore, the current of the detection points (102_1s, 102_2s, 102_3s) can be changed by adjusting the magnification and position of the movable condenser lens 210 . As shown in FIGS. 1A and 1B , the landing energy of the beams ( 102_1 , 102_2 , 102_3 ) impinging on the surface 7 of the sample can be changed by adjusting the potential of the electron source 101 and/or the surface 7 of the sample.

In a multiple electron beam setup, each beam scans a sub-FOV (field of view) of the sample surface 7, and the total field of view is the sum of the sub-fields of all beams. Each subfield is equal to or smaller than the beam spacing (Ps, Figure 1A) of the sample surface. To increase productivity, each subfield preferably has its imaging resolution selected so that its beam spacing is varied to maintain the knitting of the subfields. For high resolution, use smaller size pixels and require a smaller subfield of view to avoid excessive pixel counts. If it is a low image resolution, use larger size pixels and require a larger subfield of view to increase productivity. FIG. 2A shows an example of low image resolution. 2A, if the detection points 102_2s and 102_3s can be moved to the right and left, respectively, the beam spacing Ps will change from P1 to P2, and the total field of view will increase from 3×P1 to 3×P2, resulting in increased productivity . Therefore, it would be a more preferred function to make the beam pitch Ps selectable.

Continuous scan mode (where a sample is continuously moved so as to be normal to a scan direction of a primary electron beam) is a known method that increases the productivity of conventional single electron beam devices. If this method is used in a multiple electron beam setup, it is best to match the overall field of view, or orientation of the array of detection spots, to the direction of movement of the stage. It is well known that if there is a magnetic lens in a primary projection imaging system, its magnetic field will rotate the beam and the total field of view. Since the magnetic field changes with observation conditions, such as the landing energy and the currents of multiple beams, the rotation angle of the total field of view also changes. FIG. 2B shows an example in which the objective lens 131 of FIG. 1A is replaced by a magnetic or electromagnetic compound lens. For example, when the landing energy of the beams 102_1 to 102_3 is changed from 1 keV to 2 keV, the detection points 102_2S and 102_3S are rotated by an angle θ around the optical axis 100_1 represented by the dotted line. The change in orientation of the total field of view, however, impacts the characteristics of the continuous scan mode. Keeping the orientation of the array of detection points consistent or selectable provides more flexibility to improve productivity and is therefore a preferred feature.

For some samples, the orientation of the pattern on the sample and the orientation of the array of detection points may require a specific match. Making the orientation of the probe point array selectable can compensate for mismatches due to limited landing accuracy, thereby avoiding the time it takes to re-impact, which can increase productivity. Furthermore, in order to effectively observe some patterns of a sample, multiple beams may need to strike the surface of the sample at specific angles of incidence. If the angle of incidence was made selectable, it would provide observability of various samples, so this would be a more preferred function.

The present invention will provide a method or apparatus to achieve the desired functions described above, practiced in the form of multiple electron beam apparatuses, particularly those implemented in the related applications presented here, and as a yield management tool in the field of semiconductor manufacturing.

The applications related to this case are listed below:

(1) US patent application, publication number US 6,943,349, application date April 2001, inventor Pavel Adanec et al.

(2) US patent application, publication number US 7,244,949, filed in March 2006, inventor Ranier Knippelmeyer et al.

(3) US Patent Application, Application No. 15/065,342, filed in March 2016, inventor Weiming Ren et al.

(4) US patent application, application number 15/078,369, application date March 2016, inventor Weiming Ren et al.

(5) US patent application, application number 15/150,858, application date May 2016, inventor Xuedong Liu et al.

(6) US patent application, application number 15/213,781, application date July 2016, inventor Shuai Li et al.

(7) US patent application, application number 15/216,258, application date July 2016, inventor Weiming Ren et al.

(8) US Patent Application, Application No. 15/365,145, filing date November 2016, inventor Weiming Ren et al.

It is an object of the present invention to provide a new multi-charged particle beam apparatus that observes a sample with higher analysis rate and productivity, and increases flexibility for changing observation conditions. Based on the conventional multi-electron beam device proposed in the related application of the present invention, the present invention provides several methods to realize a new multi-charged particle beam device with variable field of view. The new multi-charged particle beam device features variable size, orientation, and angle of incidence. As a result, the novel multi-charged particle beam device can provide more flexibility to accelerate the observation of samples and make more samples observable. More specifically, the novel multi-charged particle beam apparatus can be used as a yield management tool in the semiconductor manufacturing industry to inspect and/or re-inspect wafers/reticles, and the novel multi-charged particle beam apparatus will likely be able to Achieve high productivity and detect a wider variety of defects.

According to the above object, an embodiment of the present invention provides a multi-charged particle beam device for observing a surface of a sample, which includes an electron source, a condenser lens, an electron source conversion unit, an objective lens, and a skew scanning unit , a sample stage, a beam splitter, a secondary projection imaging system, and an electronic detection device. The condenser lens is located below the electron source. The electron source conversion unit is located below the condenser lens. The thing is located below the electron source conversion unit. The skew scanning unit is located below the electron source conversion unit. The sample stage is located below the objective. The beam splitter is located below the electron source conversion unit. The electronic detection device has a plurality of detection elements. The electron source, the condenser lens, and the objective lens are aligned with an optical axis of the multi-charged particle beam device, the sample stage supports the sample, and the surface of the sample faces the objective lens. The electron source conversion unit includes a beam limiting tool having a plurality of beam limiting openings, and an image forming tool having a plurality of electron optical elements, the image forming tool being movable along the optical axis. The electron source generates a primary electron beam along the optical axis, and the condenser lens focuses the primary electron beam. The beams of the primary electron beam pass through the beam-limiting openings, respectively, and are deflected toward the optical axis by the electron optical elements to form a plurality of virtual images of the electron source, respectively. The objective lens focuses the plurality of beams on the surface of the sample to form a plurality of detection points on the surface, and the deflection scanning unit deflects the plurality of beams to be within an observation area of the surface The plurality of detection points are scanned in a plurality of scanning areas. The plurality of detection points respectively generate a plurality of secondary electron beams from the plurality of scanning areas, the secondary electron beams are guided by the beam splitter to the secondary projection imaging system, and the secondary projection imaging system focuses and maintains the The plurality of secondary electron beams are respectively detected by the plurality of detection elements, and each of the detection elements thus provides an image signal corresponding to one of the scanning areas.

In one embodiment, the deflection angles of the plurality of beams caused by the plurality of electron optical elements in the above-mentioned multi-charged particle beam device are respectively set to reduce the off-axis deflection of the plurality of detection points. By moving the image forming tool along the optical axis, the spacing between detection points can be adjusted together. The objective lens includes a magnetic lens and an electrostatic lens. The orientations of the plurality of detection points are selectable, and the orientation of the detection points can be changed by changing the zoom magnification of the magnetic lens and the electrostatic lens.

In one embodiment, the skew angle in the above-described multi-charged particle beam device ensures that the plurality of beams land on the surface in a direction orthogonal or substantially orthogonal to the surface. The skew angle ensures that multiple beams land on the surface at a specific angle. The skew scanning unit is located on a front focusing surface of the objective lens. The deflection scanning unit tilts the plurality of beams so that each beam lands on the surface at the same or substantially the same landing angle. The multi-charged particle beam apparatus may further include a beam tilt deflector located between the electron source conversion unit and the front focal plane of the objective lens. The beam tilt deflector tilts the plurality of beams so that each beam lands on the surface at the same or substantially the same landing angle.

According to the above object, an embodiment of the present invention provides a multi-charged particle beam device for observing a surface of a sample, which includes an electron source, a condenser lens, an electron source conversion unit, an objective lens, and a skew scanning unit , a sample stage, a beam splitter, a secondary projection imaging system, and an electronic detection device. The electron source conversion unit is located below the condenser lens. The objective lens is located below the electron source conversion unit. The skew scanning unit is located below the electron source conversion unit. The sample stage is located below the objective. The beam splitter is located below the electron source conversion unit. The electronic detection device has a plurality of detection elements. The electron source, the condenser lens, and the objective lens are aligned with an optical axis of the multi-charged particle beam device, the sample stage supports the sample, and the surface of the sample faces the objective lens. The electron source conversion unit includes a beam-limiting tool having a plurality of beam-limiting openings, a first image forming tool having a plurality of first electron optical elements, and a second image having a plurality of second electron optical elements A tool is formed, the second image forming tool is located under the first image forming tool and moves along a radial direction, and the first image forming tool or the second image forming tool is used as an active image forming tool. The electron source generates a primary electron beam along the optical axis, and the condenser lens focuses the primary electron beam. The beams of the primary electron beam pass through the beam-limiting openings, respectively, and are deflected toward the optical axis by the electron optical elements to form a plurality of virtual images of the electron source, respectively. The objective lens focuses the plurality of beams on the surface of the sample to form a plurality of detection points on the surface, and the deflection scanning unit deflects the plurality of beams to be within an observation area of the surface The plurality of detection points are scanned in a plurality of scanning areas. The plurality of detection points respectively generate a plurality of secondary electron beams from the plurality of scanning areas, the secondary electron beams are guided by the beam splitter to the secondary projection imaging system, and the secondary projection imaging system focuses and maintains the The plurality of secondary electron beams are respectively detected by the plurality of detection elements, and each of the detection elements thus provides an image signal corresponding to one of the scanning areas.

In one embodiment, the skew angles of the plurality of beams caused by the active image forming tool in the above-mentioned multi-charged particle beam device are respectively set to reduce the off-axis deviation of the plurality of detection points. By switching to the active image forming tool between the first image forming tool and the second shadow forming tool, the spacing between the detection points can be adjusted together. When the first image forming tool is selected, the second image forming tool is moved out to avoid blocking the plurality of beams. The objective lens includes a magnetic lens and an electrostatic lens. By changing a zoom magnification ratio of the magnetic lens and the electrostatic lens, the orientation of a plurality of detection points can be changed.

In one embodiment, the skew angle in the above-described multi-charged particle beam device ensures that the plurality of beams land on the surface in a direction orthogonal or substantially orthogonal to the surface. The skew angle ensures that multiple beams land on the surface at a specific angle. The skew scanning unit is located on a front focusing surface of the objective lens. The deflection scanning unit tilts the plurality of beams so that each beam lands on the surface at the same or substantially the same landing angle. The multi-charged particle beam apparatus may further include a beam tilt deflector located between the electron source conversion unit and the front focal plane of the objective lens. The beam tilt deflector tilts the plurality of beams so that each beam lands on the surface at the same or substantially the same landing angle.

According to the above purpose, an embodiment of the present invention provides a multi-charged particle beam device for observing a surface of a sample, comprising an electron source, a condenser lens, an electron source conversion unit, an objective lens, a skew scanning unit, A sample stage, a beam splitter, a secondary projection imaging system, and an electron detection device. The condenser lens is located below the electron source. The electron source conversion unit is located below the condenser lens. The objective lens is located below the electron source conversion unit. The skew scanning unit is located below the electron source conversion unit. The sample stage is located below the objective. The beam splitter is located below the electron source conversion unit. The electronic detection device has a plurality of detection elements. The electron source, the condenser lens, and the objective lens are aligned with an optical axis of the multi-charged particle beam device, a first principle plane of the objective lens can move along the optical axis, the sample stage supports the sample, the sample of the surface facing the objective. The electron source conversion unit includes a beam-limiting tool having a plurality of beam-limiting openings, and an image forming tool having a plurality of electron optical elements. The electron source generates a primary electron beam along the optical axis, and the condenser lens focuses the primary electron beam. The beams of the primary electron beam pass through the beam-limiting openings, respectively, and are deflected toward the optical axis by the electron optical elements to form a plurality of virtual images of the electron source, respectively. The objective lens focuses the plurality of beams on the surface of the sample to form a plurality of detection points on the surface, and the deflection scanning unit deflects the plurality of beams to be within an observation area of the surface The plurality of detection points are scanned in a plurality of scanning areas. The plurality of detection points respectively generate a plurality of secondary electron beams from the plurality of scanning areas, the secondary electron beams are guided by the beam splitter to the secondary projection imaging system, and the secondary projection imaging system focuses and maintains the The plurality of secondary electron beams are respectively detected by the plurality of detection elements, and each of the detection elements thus provides an image signal corresponding to one of the scanning areas.

In one embodiment, the deflection angles of the plurality of beams caused by the plurality of electron optical elements in the above-mentioned multi-charged particle beam device are respectively set to reduce the off-axis deflection of the plurality of detection points. By moving the first principle plane along the optical axis, the spacing between detection points can be adjusted together.

In one embodiment, the skew angle in the above-described multi-charged particle beam device ensures that the plurality of beams land on the surface in a direction orthogonal or substantially orthogonal to the surface. The skew angle ensures that multiple beams land on the surface at a specific angle. The skew scanning unit is located on a front focusing surface of the objective lens. The deflection scanning unit tilts the plurality of beams so that each beam lands on the surface at the same or substantially the same landing angle. The multi-charged particle beam apparatus may further include a beam tilt deflector located between the electron source conversion unit and the front focal plane of the objective lens. The beam tilt deflector tilts the plurality of beams so that each beam lands on the surface at the same or substantially the same landing angle. The objective lens includes a magnetic lens and an electrostatic lens. The electrostatic lens includes a field control electrode and a field moving electrode, and generates an electrostatic field. The potential of the field control electrodes is set to control the electrostatic field on the surface to ensure that electrical breakdown of the surface does not occur. The potential of the field shifting electrodes is set to shift the electrostatic field to shift the first principle plane. The orientation of the plurality of detection points can be changed by changing the potentials of the field electrodes and/or the field moving electrodes. The multi-charged particle beam device further includes an upper magnetic lens located above the lower magnetic lens. The first principle plane can be moved by changing the zoom magnification ratio of the upper magnetic lens and the lower magnetic lens. By setting the polarities of the upper magnetic lens and the lower magnetic lens, the orientation of a plurality of detection points can be changed.

According to the above object, an embodiment of the present invention provides a multi-charged particle beam device for observing a surface of a sample, comprising an electron source, a condenser lens, an electron source conversion unit, a conversion lens, a field lens, and an objective lens , a skew scanning unit, a sample stage, a beam splitter, a secondary projection imaging system, and an electronic detection device. The electron source conversion unit is located below the condenser lens. The conversion lens is located below the electron source conversion unit. The field lens is located below the conversion lens. The objective is located below the field lens. The skew scanning unit is located below the electron source conversion unit. The sample stage is located below the objective. The beam splitter is located below the electron source conversion unit. The electronic detection device has a plurality of detection elements. The electron source, the condenser lens, the conversion lens, the field lens, and the objective lens are aligned with an optical axis of the multi-charged particle beam device, the sample stage supports the sample, and the surface of the sample faces the objective lens. The electron source conversion unit includes a beam-limiting tool having a plurality of beam-limiting openings, and an image forming tool having a plurality of electron optical elements. The electron source generates a primary electron beam along the optical axis, and the condenser lens focuses the primary electron beam. The beams of the primary electron beam pass through the beam-limiting openings, respectively, and are deflected toward the optical axis by the electron optical elements to form a plurality of first virtual images of the electron source, respectively. The conversion lens images the plurality of first virtual images on an intermediate image plane, thereby forming a plurality of second real images on the intermediate image plane, and the field lens is located on the intermediate image plane and transmits the plurality of beams Bending, the lens images the plurality of second real images on the surface of the sample to form a plurality of detection points on the surface, the deflection scanning unit deflects the plurality of beams for an observation on the surface The plurality of detection points are scanned in a plurality of scanning areas in the area. The plurality of detection points respectively generate a plurality of secondary electron beams from the plurality of scanning areas, the secondary electron beams are guided by the beam splitter to the secondary projection imaging system, and the secondary projection imaging system focuses and maintains the The plurality of secondary electron beams are respectively detected by the plurality of detection elements, and each of the detection elements thus provides an image signal corresponding to one of the scanning areas.

In one embodiment, the bending angles of the plurality of beams caused by the field lens in the above-mentioned multi-charged particle beam device are respectively set to reduce the off-axis deviation of the plurality of detection points. The deflection angles of the plurality of beams due to the plurality of optical electronic elements are respectively set to adjust the spacing between the plurality of detection points. The objective lens includes a first magnetic lens and a first electrostatic lens. By changing the zoom magnification ratio of the first magnetic lens and the first electrostatic lens, the orientation of the plurality of detection points can be changed. The field lens includes a third magnetic lens and a third electrostatic lens. By changing the zoom magnification ratio of the third magnetic lens and the third electrostatic lens, the orientation of the plurality of detection points can be changed.

In one embodiment, the skew angle and bending angle of the plurality of beams due to the plurality of optical elements in the above-mentioned multi-charged particle beam device can ensure that the plurality of beams are orthogonal or substantially orthogonal to the surface. The direction landed on the surface. The skew and bending angles of the beams due to the optical elements ensure that the beams land on the surface at a particular angle. The skew scanning unit is located on a front focusing surface of the objective lens. The deflection scanning unit tilts the plurality of beams so that each beam lands on the surface at the same or substantially the same landing angle. The multi-charged particle beam apparatus may further include a beam tilt deflector located between the electron source conversion unit and the front focal plane of the objective lens. The beam tilt deflector tilts the plurality of beams so that each beam lands on the surface at the same or substantially the same landing angle.

In accordance with the above object, an embodiment of the present invention provides a method for configuring a multi-charged particle beam device for observing a surface of a sample, including the following steps: configuring an image forming tool of an electron source conversion unit, which can be along the moving an optical axis; forming a plurality of virtual images of an electron source with the image forming tool; imaging a plurality of virtual images on the surface with an objective lens and forming a plurality of detection points on the surface; and moving the image forming tool to change the spacing between the plurality of detection points.

In accordance with the above objects, embodiments of the present invention provide a method for configuring a multi-charged particle beam device for observing a surface of a sample, including the following steps: configuring a first image forming tool and a second image forming tool an electron source conversion unit, wherein the distance between the second image forming tool and an electron source is longer than the distance between the first image forming tool and the electron source, the second image forming tool can be along the multi-charged particle beam device radial movement; using the first image forming tool or the second image forming tool as an active image forming tool, wherein when the first image forming tool is used, the second image forming tool is moved away; using the active image forming tool forming tools to respectively form a plurality of virtual images of the electron source; imaging a plurality of virtual images on the surface with an objective lens and forming a plurality of detection points on the surface; and changing the active image forming tool to the first image forming tool or the second image forming tool to change the spacing between the plurality of detection points.

In accordance with the above object, an embodiment of the present invention provides a method for configuring a multi-charged particle beam device for observing a surface of a sample, comprising the following steps: configuring an objective lens having a first principle plane, the objective lens can be along the An optical axis of a multi-charged particle beam device is moved; a plurality of virtual images of an electron source are respectively formed by an image forming tool of an electron source conversion unit; a plurality of virtual images are imaged on the surface and on the surface by the objective lens forming a plurality of detection points; and moving the first principle plane to change the spacing between the plurality of detection points.

According to the above object, an embodiment of the present invention provides a method for configuring a multi-charged particle beam device for observing a surface of a sample, including the following steps: configuring a magnetic lens and a magnetic lens in the multi-charged particle beam device. The objective lens of electrostatic lens; respectively form a plurality of virtual images of an electron source with an image forming tool of an electron source conversion unit; use the objective lens to image the plurality of virtual images on the surface and form a plurality of detection points on the surface; and changing a ratio of the zoom magnification of the lower magnetic lens and the electrostatic lens to select an orientation of the plurality of detection points.

In one embodiment, the method further includes an upper magnetic lens disposed on the objective lens, the upper magnetic lens being farther from the surface than the lower magnetic lens. In one embodiment, the above method further includes changing the polarities of the upper magnetic lens and the lower magnetic lens to change the orientation of the detection point.

In accordance with the above object, an embodiment of the present invention provides a method configured in a multi-charged particle beam device for observing a surface of a sample, comprising the following steps: converting an electron source into an image processing tool of an electron source conversion unit Deviating a plurality of beams to form a plurality of first virtual images of the electron source; imaging the plurality of first virtual images on the surface with an objective lens and forming a plurality of detection points on the surface; and setting due to the The deflection angle of the plurality of beams caused by the image processing tool causes the plurality of beams to land on the surface at the same or substantially the same landing angle.

In one embodiment, the above method further includes the step of changing the landing angle by the same change amount by changing the deflection angle. In one embodiment, the above-mentioned method further includes a step of using an inclined scanning unit that tilts the plurality of beams to change the landing angle by the same amount of change. In one embodiment, the above method further includes a step of utilizing a beam tilt deflector that tilts the plurality of beams to change the landing angles of the plurality of beams by the same amount of change.

In accordance with the above object, an embodiment of the present invention provides a method configured in a multi-charged particle beam device for observing a surface of a sample, comprising the following steps: converting an electron source into an image processing tool of an electron source conversion unit A plurality of beams are deflected to form a plurality of first virtual images of the electron source; a conversion lens is used to image the plurality of first virtual images on an intermediate image plane and a plurality of second real images are formed; a field lens is used to form a plurality of second real images; set on the intermediate image plane to bend the plurality of beams; and image a plurality of second real images on the surface with an objective lens and form a plurality of detection points on the surface.

In one embodiment, the above method further includes the step of changing the deflection angle of the plurality of beams caused by the image forming tool to change the spacing of the plurality of detection points. In one embodiment, the above method further includes the step of changing the skew angle of the plurality of beams due to the image forming tool and the bending angle of the plurality of beams due to the field lens so that the plurality of beams are the same or substantially the same. The same landing angle landed on the surface. In one embodiment, the above method further includes the step of changing the tilt angle to change the landing angles of the plurality of beams by the same amount of change. In one embodiment, the above method further includes the step of using a skew scanning unit to skew the skew angles of the plurality of beams by an equal amount. In one embodiment, the above method further includes the step of using a beam tilt deflector to deflect the deflection angles of the plurality of beams by an equal amount. In one embodiment, the above method further includes the step of configuring an objective lens having a first magnetic lens and a first electrostatic lens. In one embodiment, the above method further includes the step of changing the zoom magnification ratio of the first magnetic lens and the first electrostatic lens to select an orientation of the plurality of detection points. In one embodiment, the above method further includes the step of configuring a conversion lens having a second magnetic lens and a second electrostatic lens. In one embodiment, the above-mentioned method further includes the step of selecting an orientation of the plurality of detection points by changing the zoom magnification of the second magnetic lens and the second electrostatic lens. In one embodiment, the above method further includes the step of configuring a field lens having a third magnetic lens and a third electrostatic lens. In one embodiment, the above method further includes the step of selecting an orientation of the plurality of detection points by changing the zoom magnification of the third magnetic lens and the third electrostatic lens.

According to the above objective, an embodiment of the present invention provides an apparatus including a particle source, a particle source conversion unit, and an objective lens. The particle source is used to provide a primary charged particle beam. The particle source conversion unit divides the primary charged particle beam into a plurality of charged particle beams, and forms a plurality of images of the particle source. The objective lens is located in the particle source conversion unit, and is used for projecting the plurality of images on a surface of a sample. The spacing of the charged particle beams on the surface is adjusted by changing the tilt angle of the charged particle beams before entering the objective lens.

In accordance with the above objects, embodiments of the present invention provide a device comprising a particle source for providing a primary charged particle beam, a particle source for dividing the primary charged particle beam into a plurality of charged particle beams and forming the particle source A tool for a plurality of images, an objective for projecting a plurality of images onto a surface of a sample to form a plurality of detection points on the surface, and an objective for adjusting the distance between the detection points on the surface Spacing tool.

According to the above object, an embodiment of the present invention provides a method for observing a sample surface, comprising the following steps: providing a plurality of charged particle beams having a plurality of intersections; forming a plurality of detection points on the sample surface; scanning the plurality of detection points on the sample surface; and changing the deflection angles of the plurality of charged particle beams, so that the spacing between the plurality of detection points is adjusted.

Other advantages and features of the present invention can be more clearly understood from the various embodiments described in the following drawings and related texts.

The various embodiments of the present case will be described in detail below, and the drawings will be used as examples. By way of illustration and not limitation, the drawings and descriptions are of an electron beam by way of example. However, in other embodiments of the invention, other charged particle beams may also be used.

In the drawings, the dimensions of elements may be exaggerated for clarity, and the elements may not be shown in scale. The same or similar reference numerals in the drawings represent the same or similar elements, and only the differences between the individual elements are described.

For each/all embodiments disclosed in this specification, those skilled in the art can make various modifications, changes, combinations, exchanges, omissions, substitutions, and equivalent changes accordingly, as long as they are not mutually exclusive, they all belong to the concept of the present invention , belong to the scope of the present invention. The detailed descriptions made in the embodiments of the present invention are illustrative rather than limiting.

In this specification, "axial" refers to an electronic optical element, such as a round lens or a multipole lens, or the direction of the optical axis of an imaging system or a device. "Radial" refers to a radial direction orthogonal to the optical axis. "On-axial" means on or aligned with the optical axis. "Off-axial" means not on or aligned with the optical axis.

In this specification, "an imaging system aligned with an optical axis" means that all electronic optical elements, such as a round lens or a multipole lens, are aligned with the optical axis.

In this specification, the X, Y, and X coordinates form Cartesian coordinates, and the optical axis of the primary projection imaging system is at the Z coordinate along which the primary electron beam travels.

In this specification, "primary electrons" refer to electrons emitted from an electron source and incident on a surface to be observed or inspected of a sample. "Secondary electrons" refer to electrons generated by primary electrons incident on the surface of the sample to be measured.

In this specification, "spacing" refers to the distance between two adjacent beamlets or charged particle beams in a plane.

In this specification, "the effective deflection plane of the deflector" refers to the plane of the deflector that is equivalent to the total deflection function (the plane where the total deflection function of the deflector can be equivalent to happen).

Based on some of the multi-electron beam devices proposed in the related applications of the present application, the present invention proposes a new multi-charged particle beam device with a variable field of view (FOV). Among other things, the overall field of view of the new multi-charged particle beam device can vary in size, orientation, and illumination angle. In order to express the method of the present case clearly, the present embodiment takes the multi-electron beam device of FIG. 1B as an example. In order to simplify the description, the number of beams of the new multi-charged particle beam device is simplified to three. However, in other embodiments of the present invention, the number of beams is not limited and can be any number. Additionally, one of the three beams is on-axis, but in other embodiments, all three beams may be off-axis. Furthermore, elements not relevant to the present invention, such as the skew scanning unit and the beam splitter, are not shown in the figures or even mentioned in the description.

。同理，探測點102_1s和102_3s的間距是由偏斜角α3以及物鏡131的第一焦距f所決定，並可簡單表示成

。In each of the known multiple electron beam devices, an image forming tool is used to deflect the plurality of beams towards the optical axis. The skew angles of the multiple beams are set such that the off-axis deviation of the multiple detection points due to the objective lens is minimized. Thus, the plurality of deflected beams typically pass through or near the front focal point of the objective, that is, form an on-axis intersection at or near the front focal plane of the objective ( on-axis crossover). Therefore, the spacing between the detection points depends on the deflection angles of the beams and the first or object focal length of the objective. Therefore, the spacing of the beams can be adjusted by changing the deflection angle and/or the first focal length of the objective lens. For example, as shown in FIGS. 1A and 1B , the skew angles α2 and α3 of the two off-axis beams 102_2 and 102_3 may be set such that the off-axis deviation of the detection points 102_2s and 102_3s due to the objective lens 131 is minimized. Therefore, the beams 102_2 and 102_3 generally pass through or near the front focal point of the objective lens 131 , that is, crossover (CV) with the optical axis at or near the front focal plane of the objective lens 131 . The distance between the detection points 102_1s and 102_2s is determined by the deflection angle α2 and the first focal length f of the objective lens 131, and can be simply expressed as

. Similarly, the distance between the detection points 102_1s and 102_3s is determined by the deflection angle α3 and the first focal length f of the objective lens 131, and can be simply expressed as

.

3A, FIG. 4A and FIG. 5A show the embodiment of the multi-charged particle beam device 300A, 400A, 500A by changing the skew angle to adjust the detection point spacing according to the embodiment of the present invention, and FIG. 6A shows the embodiment of the present invention 600A by changing the first An embodiment of adjusting the distance between detection points by the focal length. As shown in FIG. 3A , the electron source conversion unit 320 of the multi-charged particle beam apparatus 300A includes a beam limiting tool 121 having three beam limiting openings 121_1 , 121_2 , and 121_3 . The electron source conversion unit 320 also includes a movable image forming tool 322 having three electron optical elements 322_1, 322_2, 322_3. The effective deflection plane 322_0 of the movable image forming tool 322 can be moved along the optical axis 300_1 within a variation range 322_or. When the effective deflection plane 322_0 moves closer to the objective lens 131, the distance between the detection points will become larger, and vice versa.

和

，其中f是物鏡131的第一焦距。圖3C的有效偏斜平面322_0是在靠近物鏡131的D2位置上，而不是D1位置。因此，偏斜角α2和α3被增加，而偵測點之間的間距變大。如圖3C所示，探測點102_2s和102_3s由原先的圖3B的虛線位置向外移動。Figure 3B shows the paths of the three beams 102_1, 102_2, 102_3 when the effective deflection plane 322_0 is at position D1. The movable condenser lens 210 collimates the primary electron beam 102 to enter the electron source conversion unit 320 at a normal angle within the variation range 210_2. Beam limiting openings 121_1, 121_2, 121_3 divide the electron source into an on-axis beam 102_1 and two off-axis beams 102_2, 102_3. The two off-axis electron optical elements 322_2, 322_3 deflect the beams 102_2, 102_3, respectively, towards the optical axis 300_1. The objective lens 131 focuses the three beams 102_1, 102_2, 102_3 on the surface 7 of the sample 8, thereby forming three detection points 102_1s, 102_1s, 102_3s, respectively. The deflection angles α2 and α3 of the beams 102_2 and 102_3, respectively, are set such that the off-axis deviation of the detection points 102_2 and 102_3 is minimized. The beams 102_2 and 102_3 thus pass through the front focal point of the objective lens 131 , that is to say, form an intersection on the optical axis 300_1 of the front focal plane of the objective lens 131 . The two distances formed by the three detection points are approximately

and

, where f is the first focal length of the objective lens 131 . The effective deflection plane 322_0 of FIG. 3C is at the D2 position near the objective lens 131 instead of the D1 position. Therefore, the skew angles α2 and α3 are increased, and the distance between the detection points becomes larger. As shown in FIG. 3C, the detection points 102_2s and 102_3s are moved outward from the original dotted line positions of FIG. 3B.

Compared with the prior art of FIG. 1B , as shown in FIG. 4A , the electron source conversion unit 420 of the multi-charged particle beam device 400A of the present embodiment further includes an image forming tool 124 having three electron optical elements 124_1 , 124_2 , and 124_3 . The image forming tool 124 is located below the image forming tool 122 and can be moved in the radial direction; therefore, the electron source conversion unit 420 has two modes of operation. As shown in FIG. 4B, in the first mode, the image forming tool 122 is used to form the three first virtual images of the single electron source 101, and the image forming tool 124 is moved out of the path of the beams 102_1, 102_2, 102_3 . As shown in FIG. 4B , in the second mode, the image forming tool 122 is turned off and the image forming tool 124 is moved back to its original position to form three first virtual images of the electron source 101 . In the first mode, the deflection angles α2 and α3 of the beams 102_2 and 102_3 are smaller than the deflection angles α2 and α3 in the second mode. Therefore, the two spacings of the three detection points in the second mode will be larger than those in the first mode.

As shown in FIG. 5A , compared with the multi-electron beam device of FIG. 1B , the multi-charged particle beam device 500A of this embodiment further includes a conversion lens 533 and a field lens 534 between the electron source conversion unit 220 and the objective lens. Therefore, the conversion lens 533, the field lens 534, and the objective lens 131 constitute a primary projection imaging system. Figure 5B shows the paths of the beams 102_1, 102_2, 102_3. The movable condenser lens 210 collimates the primary electron beam 102 so that it is orthogonally incident into the electron source conversion unit 220 . The beam-limiting openings 121_1, 121_2, 121_3 divide the primary electron beam into one on-axis beam 102_1, and two off-axis beams 102_2 and 102_3. The two off-axis electron optical elements 122_2 and 122_3 deflect the beams 102_2 and 102_3, respectively, towards the optical axis 500_1. Three first virtual images of the single electron source are then formed. The conversion lens 533 then focuses the three beams 102_1 , 102_2 , 102_3 on the intermediate image plane PP1 , ie projects three virtual first images thereon. Thus, three second real images 102_1m, 102_2m, 102_3m of the single electron source 101 are formed. Field lens 534 is located on intermediate image plane PP1 and steers off-axis beams 102_2 and 102_3 towards optical axis 500_1 without affecting their focusing. The objective 131 then focuses the three beams 102_1 , 102_2 , 102_3 on the surface 7 of the sample 8 , ie projects three second real images on the surface 7 . Next, on the surface 7 of the sample 8, three detection points 102_1s, 102_2s, and 102_3s are respectively formed.

。同理，探測點102_1s和102_3s是由彎曲角γ3以及物鏡131的第一焦距f決定，亦可以簡單表示成

。彎曲角γ2和γ3會隨著第二真實影像102_2m和102_3m的徑向移動而改變，而由於電子光學元件122_2和122_3，徑向移動會隨著射束102_2和102_3的偏斜角α2和α3而改變。因此，探測點之間的兩個間距可透過調整偏斜角α1和α2而改變。如圖5C所示，偏斜角α1和α2被調整使其大於圖5B的偏斜角α1和α2，使兩個離軸的探測點102_2s和102_3s由原先的虛線位置(圖5B)移動到現在圖5C所示的位置，造成探測點之間的兩個間距變大。As shown in FIG. 5B, the bending angles γ2 and γ3 of the beams 102_2 and 102_3 due to the field lens 534, respectively, are set such that the off-axis deviation of the detection points 102_2s and 102_3s is minimized. The beams 102_2 and 102_3 thus pass through or are close to the front focus of the objective lens 131 , ie make a cross on the optical axis 500_1 at or near the front focus plane of the objective lens 131 . The detection points 102_1s and 102_2s are determined by the bending angle γ2 and the first focal length f of the objective lens 131, which can also be simply expressed as

. Similarly, the detection points 102_1s and 102_3s are determined by the bending angle γ3 and the first focal length f of the objective lens 131, which can also be simply expressed as

. The bending angles γ2 and γ3 vary with the radial movement of the second real images 102_2m and 102_3m, while the radial movement varies with the deflection angles α2 and α3 of the beams 102_2 and 102_3 due to the electron optical elements 122_2 and 122_3 Change. Therefore, the two spacings between the detection points can be changed by adjusting the deflection angles α1 and α2. As shown in Fig. 5C, the deflection angles α1 and α2 are adjusted to be larger than the deflection angles α1 and α2 of Fig. 5B, so that the two off-axis detection points 102_2s and 102_3s are moved from the original dotted line positions (Fig. 5B) to the present The position shown in Fig. 5C causes the two distances between the detection points to become larger.

As shown in FIG. 6A , the first-principle plane 631_2 of the objective lens 631 of the multi-charged particle beam device 600A can be displaced along the optical axis 600_1 within a variation range 631_2r. This axial displacement can be accomplished by mechanically moving the position of the objective lens 631, or by electronically changing the shape or position of the objective lens field. As the first principle plane approaches the surface 7 of the sample 8 , the first focal length f becomes smaller and the first focal plane will move towards the surface 7 . In addition, when the first focusing surface is moved downward, the deflection angles of the plurality of beams become smaller; thus, the spacing between the plurality of detection points becomes smaller.

6B and 6C respectively show the paths of the three beams when the first principle plane 631_2 is at positions D3 and D4, respectively. The D3 position is closer to the surface 7 of the sample 8 than the D4 position. Therefore, the first focal length f of FIG. 6B and the deflection angles α2 and α3 of the beams 102_2 and 102_3 are smaller than the first focal length f of FIG. 6C and the deflection angles α2 and α3 of the beams 102_2 and 102_3 . As shown in FIG. 6C , the detection points 102_2s and 102_3s are moved outward from the original dotted line positions ( FIG. 6B ), and the distance between the two detection points becomes larger compared to FIG. 6B .

As shown in FIG. 1C, the objective lens 131-1 of the conventional multi-electron beam device is an electromagnetic compound lens. The objective includes a magnetic lens and an electrostatic lens, and operates in a delayed mode (the landing energy of electrons is lower than the energy of electrons passing through the objective) due to low geometric aberrations and low radiation damage to the sample. The magnetic lens is composed of a coil 131_c1 and a yoke 131_y1 having magnetic poles 131_mp1 and 131_mp2. The electrostatic lens is composed of the magnetic pole 131_mp1 , the field control electrode 131_e1 and the sample 8 . The potential of the magnetic pole 131_mp1 is higher than that of the sample 8 . The potential of the field control electrode 131_e1 is set to control the electric field of the surface 7 of the sample 8 . The electric field can ensure no electrical breakdown of the surface 7, reduce geometric aberrations at multiple detection points, control the charge of the surface 7 by reflecting some of the secondary electrons, or increase the collection of secondary electrons. As shown in Figure 1C, the shape of the magnetic field cannot be changed, while the shape of the electrostatic field can only be changed within a limited range. As a result, conventional objective lenses are hardly electrically controllable, that is, by changing the potential of the electrodes and/or changing the excitation current of the coils to move them.

According to the conventional objective lens 131-1 of Fig. 1C, Figs. 7A, 7B and 7C of the present invention respectively provide three novel movable objective lenses 631-1, 631-2 and 631-3. As shown in FIG. 7A, compared to FIG. 1C, the objective lens 631-1 further includes an electrode 631-1_e2 between the magnetic pole 131_mp1 and the field control electrode 131_e1. Therefore, the electrostatic lens is composed of the magnetic pole 131_mp1, the electrode 631-1_e2, the field control electrode 131_e1, and the sample 8. The shape of the electrostatic field of the electrostatic lens can be changed by adjusting the potential of the field control electrode 131_e1 and the potential of the electrode 631-1_e2. When the potential of the electrode 631-1_e2 is adjusted to be close to the potential of the magnetic pole 131_mp1, the electrostatic field is compressed toward the sample 8, which is equivalent to moving the objective lens 631-1 toward the sample 8. Therefore, the electrode 631-1_e2 may also be referred to as a field moving electrode.

As shown in FIG. 7B, compared to FIG. 1C, the objective lens 631-2 further includes two electrodes 631-2_e2 and 631-2_e3 located in the groove of the yoke 131_y1 and on the field control electrode 131_e1. Therefore, the electrostatic lens is composed of the electrodes 631-2_e3 and 631-2_e2, the field control electrode 131_e1, and the sample 8. The potential of the electrode 631-2_e3 is higher than that of the sample 8, and may also be equal to the potential of the magnetic pole 131_mp1. The shape of the electrostatic field of the electrostatic lens can be changed by adjusting the potential of the electrode 131_e1 and the potential of the electrode 631-2_e2. Similar to the embodiment of FIG. 7A, in the embodiment of FIG. 7B, when the potential of the electrode 631-2_e2 is adjusted to be close to the potential of the electrode 631-1_e3, the electrostatic field is compressed toward the sample 8, which is equivalent to moving the objective lens 631-2 toward the sample 8. Therefore, the electrode 631-2_e2 may also be referred to as a field moving electrode. Compared to the objective lens 631-1 of FIG. 7A, the magnetic lens of the embodiment of FIG. 7B can be placed closer to the sample 8, thus providing a deeper magnetic immersion of the sample 8, resulting in smaller deviation.

As shown in FIG. 7C , compared with FIG. 1C , the objective lens 631-3 further includes a coil 631-3_c2 and a yoke 631-3_y2 located in the groove of the yoke 131_y1 and on the magnetic pole 131_mp1. Therefore, a lower magnetic lens, an upper magnetic lens, and an electrostatic lens are formed. Wherein, the lower magnetic lens is generated by the coil 131_c1 through the low magnetic current gap G1 between the magnetic pole 131_mp1 and the magnetic pole 131_mp2 of the yoke 131_1 to generate a lower magnetic field. The upper magnetic lens is generated by the coil 631-3_c2 through the magnetic current gap G2 between the magnetic pole 131_mp1 and the magnetic pole 631-3_mp3 of the yoke 631-3_y2 to generate an upper magnetic field. The electrostatic lens is composed of the magnetic pole 131_mp1, the field control electrode 131_e1, and the sample 8. The distribution shape of the total magnetic field of the objective lens 631-3 will change with the combination of the above-mentioned upper and lower magnetic fields. Therefore, the excitation ratio of the lower magnetic lens and the upper magnetic lens can be adjusted, or the current ratio of the coils 131_c1 and 631-3_c2 can be adjusted. and change. When the adjustment current is relatively high, the total magnetic field of the objective lens 631-3 is squeezed toward the sample 8, which is equivalent to moving the objective lens 631-3 toward the sample 8. Two extreme examples are illustrated here. When the coil 131_c1 is turned off and the coil 631-3_c2 is turned on, the total magnetic field of the objective lens 631-3 is located at the upper side; in addition, when the coil 131_c1 is turned on and the coil 631-3_c2 is turned off, the total magnetic field of the objective lens 631-3 is located. at the bottom. The embodiment of FIG. 7C can be arbitrarily combined with the embodiments of FIGS. 7A and 7B to practice more embodiments of the objective lens 631 .

In the following embodiments, methods of rotating the detection point array will be proposed, which can be used to eliminate azimuthal variation of the overall field of view with respect to the observation conditions, and/or to precisely match the orientation of the sample pattern and the orientation of the detection point array. As mentioned earlier, the objective lens of the conventional multi-electron beam device is an electromagnetic compound lens, such as the objective lens 131-1 shown in FIG. 1C. Therefore, a proper combination of the zoom magnifications of the magnetic lens and the electrostatic lens can make the detection point rotate by an angle around the optical axis. For example, if objective 131 in FIG. 1A is similar to objective 131-1 in FIG. 1C , field control electrodes 131_e1 can be used to rotate detection points 102_2s and 102_3s to an angle and control the electric field of surface 7 of sample 8 . In order to maintain the electric field of the surface 7 below an allowable value based on the safety of the sample, the potential of the field control electrode 131_e1 can be adjusted within a certain range, for example, between 3 kV and 5 kV relative to the sample. The focusing magnification of the electrostatic lens changes with the potential of the field control electrode 131_e1 , so the focusing magnification of the magnetic lens must be changed to keep the multiple beams focused on the surface 7 of the sample 8 . The change of the focus magnification of the magnetic lens causes the rotation angle of the detection points 102_2S and 102_3S to change. Therefore, the rotation angles of the detection points 102_2s and 102_3s can be changed by adjusting the potential of the field control electrode 131_e1 within a specific range.

For the multi-charged particle beam devices 300A, 400A and 500A of FIGS. 3A , 4A and 5A, if the structure of the objective lens 131 is similar to that of the objective lens 131-1 of FIG. 1C, the angle of the detection point array can be adjusted by this method. For the multi-charged particle beam device 600A of FIG. 6A, if the objective lens 631 has the structures of the objective lenses 631-1, 631-2, 631-3 as shown in FIGS. 7A to 7C, the field control electrode 131_e1 and/or the corresponding field move Electrodes can be used to control the rotation of the array of detection points. For the objective lens 631-3, the orientation of the detection point can be changed by changing the polarities of the magnetic fields of the upper and lower magnetic lenses. For magnetic lenses, it is well known that the rotation angle is related to the polarity of the magnetic field but not to the focusing magnification. When the polarities of the magnetic fields of the upper magnetic lens and the lower magnetic lens are the same, the upper magnetic lens and the lower magnetic lens rotate the detection point array in the same direction. When the polarities of the magnetic fields of the upper magnetic lens and the lower magnetic lens are opposite, the upper magnetic lens and the lower magnetic lens rotate the detection point array in opposite directions. Therefore, for a required focusing magnification and the corresponding position of the first principle plane, the objective lens 631-3 can generate two different rotation directions of the detection point array.

As shown in Figure 5A, the conversion lens 533 and field lens 534 of the multi-charged particle beam 500A provide more possibilities for rotating the array of detection spots. 8A shows a multi-charged particle beam device 510A according to another embodiment of the present invention, wherein the electromagnetic compound conversion lens 533-1 includes an electrostatic conversion lens 533_11 and a magnetic conversion lens 533_12. The magnetic field of the magnetic conversion lens 533_12 can be adjusted to change the rotation angle of the detection point array; thus the electrostatic field of the electrostatic conversion lens 533_11 can be changed accordingly to keep the three real images 102_1m, 102_2m, 102_3m on the intermediate image plane PP1. 8B shows a multi-charged particle beam apparatus 520A according to another embodiment of the present invention, wherein the electromagnetic compound field lens 534-1 includes an electrostatic field lens 534_11 and a magnetic field lens 534_12. The magnetic field of the magnetic field lens 531_12 can be adjusted to change the rotation angle of the detection point array. The electrostatic field of the electrostatic field lens 534_11 can be changed accordingly to generate the required bending angles of the multiple beams.

In each of the foregoing embodiments, the plurality of beams are incident orthogonally or substantially orthogonally to the surface 7 of the sample 8, that is, the angle of incidence or landing angle of the beams (the angle between the beam and the normal vector of the surface 7) close to zero. In order to effectively observe some patterns of sample 8, the angle of incidence is preferably slightly greater than zero. To ensure that multiple beams behave the same, the multiple beams must have the same angle of incidence. To achieve this, the crossover of the multiple beams must be moved out of the optical axis. This can be achieved using an image forming tool or a further beam tilt deflector.

FIG. 9A shows a method of how the image forming tool 122 tilts the plurality of beams 102_1 , 102_2 , 102_3 in the multi-charged particle beam apparatus 100A. The skew angle α1 of FIG. 1B is zero, while the skew angles α1 , α2 , α3 of FIG. 9A are increased by the same amount, so that the intersection of the beams 102_1 , 102_2 , 102_3 is moved away from the optical axis 100_1 and moved to or Close to the first focal plane of the objective lens 131 . The beams 102_1 , 102_2 , 102_3 thus land obliquely on the surface 7 of the sample 8 with the same deflection or landing angle. Likewise, the previously described multi-charged particle beam apparatuses 300A, 400A, 500A, and 600A can tilt each beam with the corresponding image forming tool. For the beams 102_1, 102_2, 102_3 of the multi-charged particle beam devices 300A, 400A, and 600A, the paths are similar to those of the respective beams of FIG. 9A. However, the paths of each beam of the multi-charged particle beam device 500A are slightly different, as shown in FIG. 9B . The skew angle α of FIG. 5B is zero, while the skew angles α1 , α2 , α3 of the three beams 102_1 , 102_2 , 102_3 of FIG. 9B are offset by three second real images 102_1m , 102_2m , 102_3m The same or substantially the same distance. The intersection of the beams 102_1 , 102_2 , 102_3 bent by the field lens 534 is thus still on or close to the first focal plane, but offset from the optical axis 500_1 .

FIG. 10 shows a multi-charged particle beam apparatus 700 that utilizes a beam tilt deflector 135 to tilt the beams 102_1 , 102_2 , 102_3 according to another embodiment of the present invention. Compared to FIG. 1B , the beam tilt deflector 135 simultaneously deflects the beams 102_1 , 102_2 , 102_3 so that their cross CVs are all moved out of the optical axis and moved to the first focus surface of the objective lens 131 or close to the first focus face. Likewise, the beam tilt deflector 135 can also be applied to other embodiments of the present invention, such as multi-charged particle beam devices 300A, 400A, 500A, 600A, to deflect multiple beams together. The beam tilt deflector 135 can be disposed between the electron source conversion unit and the front focal plane of the objective lens, and preferably, close to the electron source conversion unit. Furthermore, if the skew scan unit of the previous embodiments is on the front focal plane of the objective, the skew scan unit can move the intersection of the multiple beams, thus eliminating the need for a beam skew deflector 135.

Although the multi-charged particle beam devices of the embodiments of the present application use one or two methods to change the size, orientation, or incident angle of the field of view, those skilled in the art can make various combinations accordingly, as long as they are not mutually exclusive, All belong to the concept and scope of the present invention. For example, in one embodiment of the multi-charged particle beam apparatus, a movable image forming tool may be used, as well as a movable objective lens. In another embodiment, an objective lens, a conversion lens, and a field lens are used. Although the multi-electron beam apparatus 200A of FIG. 2B is used as an example in each embodiment, the apparatuses, components and/or methods of the present invention can also be applied to other conventional multi-electron beam apparatuses, such as the multi-electron beam apparatus of FIG. 1A , These variant embodiments all belong to the scope of the present invention.

In conclusion, based on the various conventional multi-charged particle beam devices proposed in the related applications, the present invention proposes a new multi-charged particle beam device including a variety of methods or components to make the overall field of view of the device variable in size, orientation, and / or angle of incidence. Therefore, the novel multi-charged particle beam device provides more flexibility, so that the observation speed of the sample and the observation quality of the sample are improved. More specifically, the novel multi-charged particle device as a yield management tool has the opportunity to achieve high productivity and detect a wider variety of defects. The present invention proposes three methods to vary the spacing at which multiple beams are incident on the surface of the sample. The methods include using a movable image forming tool in the electron source conversion unit, or including using a movable objective lens, or using a conversion lens and a field lens between the electron source conversion unit and the objective lens to change the size of the total field of view. The present invention proposes three methods to rotate the array of detection points so that the orientation of the total field of view is changed. These methods include using an electromagnetic compound objective and changing its electric field, using an objective with two magnetic lenses and setting the two magnetic lenses to have opposite polarities, using a magnetic lens and a conversion lens or field lens, or the magnetic lens plus Conversion lens and field lens. The present invention proposes three methods to move the intersection of the multiple beams off the optical axis so that the landing angles of the multiple beams on the surface of the sample are changed the same. The deflection of the beams can be accomplished by image forming tools, or by adding beam tilt deflectors, or tilting the scanning unit.

The above-mentioned embodiments are only intended to illustrate the technical ideas and characteristics of the present invention, and their purpose is to enable those who are familiar with the art to understand the content of the present invention and implement them accordingly. Various equivalent changes or modifications accomplished without departing from the spirit disclosed in the present invention are all included in the scope disclosed in the present invention, and should be included in the following patent application scope.

7: Surface 8: Sample 101: Electron Source 102: Primary Electron Beam 110: Condenser lens 120: Electron source conversion unit 121: Beam Limiting Tool 122: Image forming tools 123: Pre-beam bending tool 124: Image forming tools 131: Objective lens 131-1: Objective lens 210: Movable condenser lens 210_2: Range of change 220: Electron source conversion unit 300: Multi-charged particle beam device 320: Electron Source Conversion Unit 322: Movable Image Forming Tool 420: Electron Source Conversion Unit 533: Conversion Lens 534: Field Lens 631: Objective lens 100_1: Optical axis 100_1: Optical axis 100_1: Optical axis 100A: Multi-charged particle beam device 102_1: Beam 102_1: Probe point 102_1m: The second real image 102_2: Beam 102_2: Probe point 102_2m: The second real image 102_3: Beam 102_3: Probe point 102_3m: The second real image 121_1: Electron beam confinement opening 121_2: Electron beam confinement opening 121_3: Electron beam confinement opening 122_1: Electron Optical Components 122_2: Electron Optical Components 122_3: Electron Optical Components 123_1: Pre-bend Microdeflector 123_2: Pre-bend Microdeflector 123_3: Pre-bend Microdeflector 124_1: Electron Optical Components 124_2: Electron Optical Components 124_3: Electron Optical Components 131_c1: Coil 131_e1: Field control electrode 131_mp1: Magnetic pole 131_mp2: Magnetic pole 131_y1: Yoke 135: Beam tilt deflector 300_1: Optical axis 300A: Multi-charged particle beam device 322_0: Effective skew plane 322_1: Electron Optical Components 322_2: Electron Optical Components 322_3: Electron Optical Components 322_or: range of change 400A: Multi-charged particle beam device 500_1: Optical axis 500A: Multi-charged particle beam device 510A: Multiple Charged Particle Beam Apparatus 520A: Multi-charged particle beam device 533_11: Electrostatic conversion lens 533_12: Magnetic conversion lens 533-1: Electromagnetic Compound Conversion Lens 534_11: Electrostatic field lens 534_12: Magnetic Field Lens 534-1: Electromagnetic Compound Field Lenses 600_1: Optical axis 600A: Multi-charged particle beam device 631_1: First Principles Plane 631_2r: Variation range 631-1: Objective lens 631-1_e2: Electrode 631-2: Objective lens 631-2_e2: Electrode 631-2_e3: Electrode 631-3 : Objective lens 631-3_2: Yoke 631-3_c2: Coil 700_1: Optical axis 700A: Multi-charged particle beam device G1: Magnetic current spacing G2: Magnetic current spacing PP1: Intermediate image plane Ps: Spacing α1: skew angle α2: skew angle α3: skew angle γ2: Bending angle γ3: Bend angle

The technical content of this case can be easily understood through the following description and drawings. Similar element numbers in the drawings represent the same or similar structural elements, and the drawings include:

1A and FIG. 1B are schematic diagrams showing the structure of the conventional multi-electron beam device of the fifth application as listed in the related antecedents of the present application.

FIG. 1C is a schematic diagram showing the structure of a conventional electromagnetic compound objective lens.

2A and 2B are schematic diagrams showing the total field of view of variable size and orientation.

3A is a schematic diagram showing the structure of a multi-charged particle beam apparatus according to an embodiment of the present invention.

3B and 3C are schematic diagrams showing the overall field of view of variable size and orientation of a multi-charged particle beam device according to the embodiment of FIG. 3A.

FIG. 4A is a schematic diagram showing the structure of a multi-charged particle beam apparatus according to another embodiment of the present invention.

4B and 4C are schematic diagrams showing the overall field of view of variable size and orientation of a multi-charged particle beam device according to the embodiment of FIG. 4A.

FIG. 5A is a schematic diagram showing the structure of a multi-charged particle beam apparatus according to another embodiment of the present invention.

5B and 5C are schematic diagrams showing the overall field of view of variable size and orientation of a multi-charged particle beam device according to the embodiment of FIG. 5A.

6A is a schematic diagram showing the structure of a multi-charged particle beam apparatus according to another embodiment of the present invention.

6B and 6C are schematic diagrams showing the overall field of view of variable size and orientation of a multi-charged particle beam device according to the embodiment of FIG. 5A.

7A to 7C show the structure of the movable objective lens as shown in FIG. 6A according to another three embodiments of the present invention.

8A and 8B are schematic diagrams showing the structure of a multi-charged particle beam apparatus according to another embodiment of the present invention.

FIG. 9A shows tilting the multiple electron beams of the multiple electron beam device of FIG. 1B according to another embodiment of the present invention.

9B shows the tilt of the multi-charged particle beam of the multi-charged particle beam apparatus according to the embodiment of FIG. 5A of the present invention.

FIG. 10 is a schematic diagram showing the structure of a multi-charged particle beam apparatus according to another embodiment of the present invention.

7: Surface

8: Sample

131: Objective lens

210: Movable condenser lens

320: Electron Source Conversion Unit

322: Movable Image Forming Tool

121_1: Electron beam confinement opening

121_2: Electron beam confinement opening

121_3: Electron beam confinement opening

210_2: Range of change

300_1: Optical axis

300A: Multi-charged particle beam device

322_0: Effective skew plane

322_1: Electron Optical Components

322_2: Electron Optical Components

322_3: Electron Optical Components

322_or: range of change

Claims (21)

A source-conversion unit comprising: a beamlet-limit device having a plurality of beam-limiting openings configured to allow passage of the plurality of beams; and An image forming device movable along a principal optical axis and comprising a plurality of electron-optical elements, wherein at least a portion of the plurality of electron-optical elements is configured to direct at least a portion of the plurality of beams The principal optical axis is skewed. The source conversion unit of claim 1, wherein the deflection of the at least a portion of the plurality of beams toward the main optical axis forms a plurality of virtual images of an electron source. A source conversion unit as in claim 1 or 2, wherein the at least a portion of the plurality of electron optical elements is configured to deflect at least a portion of the plurality of beams at a skew angle to reduce the plurality of detections Off-axis aberrations of probe spots. The source conversion unit of claim 3, wherein the plurality of detection points have a distance that can be changed together by moving the image forming device along the main optical axis. The source conversion unit of claim 3, wherein the plurality of detection points have an orientation selectable by changing a ratio of focusing powers of a magnetic lens and an electrostatic lens. The source conversion unit of claim 3, wherein the skew angles cause the at least a portion of the plurality of beams to land orthogonally or substantially orthogonally on a surface of a sample. The source conversion unit of claim 3, wherein the deflection angles cause the at least a portion of the plurality of beams to land obliquely on a surface of a sample at the same or substantially the same landing angle. A multi-beam device comprising: an electron source configured to generate a charged particle beam along a principal optical axis; A source conversion unit, which includes: a beam-limiting device having a plurality of beam-limiting openings configured to allow passage of a plurality of beams of the charged particle beam; An image forming device movable along the principal optical axis and comprising a plurality of electron-optical elements, wherein at least a portion of the plurality of electron-optical elements is configured to direct at least a portion of the plurality of beams the principal optical axis is skewed; and An objective lens that can be configured to focus the plurality of beams on a surface of a sample to form a plurality of detection points. The multi-beam device of claim 8, wherein the deflection of the at least a portion of the plurality of beams toward the main optical axis forms a plurality of virtual images of the electron source. The multi-beam device of claim 8 or 9, wherein the objective lens comprises a magnetic lens and an electrostatic lens. The multi-beam device of claim 10, wherein the magnetic lens and the electrostatic lens are configured to select an orientation of the plurality of detection points by changing a ratio of zoom magnifications of the magnetic lens and the electrostatic lens. A multi-beam device as in claim 8 or 9, wherein the plurality of detection points have a spacing that can be changed together by moving the image forming device along the main optical axis. A multi-beam device as in claim 8 or 9, wherein the at least a portion of the plurality of electron optical elements is configured to deflect at least a portion of the plurality of beams at a skew angle to reduce the plurality of beams off-axis aberration of each detection point. The multi-beam device of claim 13, wherein the deflection angles cause the at least a portion of the plurality of beams to land orthogonally or substantially orthogonally on a surface of a sample. The multi-beam device of claim 13, wherein the deflection angles cause the at least a portion of the plurality of beams to land obliquely on a surface of a sample at the same or substantially the same landing angle. The multi-beam device of claim 8, further comprising a skew scanning unit positioned above a front focal plane of the objective. The multi-beam device of claim 16, wherein the deflection scanning unit is configured to tilt the plurality of beams to land obliquely on the surface at the same or substantially the same landing angle. The multi-beam device of claim 8, further comprising a beam tilt deflector located between the source conversion unit and a front focal plane of the objective. The multi-beam device of claim 18, wherein the beam tilt deflector is configured to tilt the plurality of beams to land obliquely on the surface at the same or substantially the same landing angle. A method of configuring a multi-beam device for viewing a surface of a sample, the method comprising: forming virtual images of an electron source using an image forming device, wherein the virtual images are used to form detection points on the surface; The image forming device is moved along a main axis to change the distance between the plurality of detection points. The method of claim 20, further comprising forming the plurality of detection points on the sample using an objective lens to image the plurality of virtual images on the surface.

Images