TW202318469A - 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 to a device that uses multiple charged particle beams to obtain images of multiple scanning areas simultaneously. Therefore, the apparatus provided by the present invention can be used to inspect and/or review wafers or reticles in the field of semiconductor manufacturing in a high-resolution and high-throughput manner.

The following descriptions and examples in this section are not the prior art admitted by this application.

In the process of manufacturing semiconductor circuit wafers, pattern defects or unacceptable particles (such as residues) will inevitably appear on the surface of the wafer or the 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 make the performance of the wafer meet the higher and higher requirements, smaller patterns and smaller critical feature sizes are adopted. Thus, due to the diffraction effect, the traditional yield management tools using light beams gradually become incompetent, and are gradually replaced by yield management tools using particle beams. Compared with photon beams, electron beams have shorter wavelengths and thus provide better spatial resolution. At present, the yield management tool using electron beams adopts the single electron beam principle of a Scanning Electron Microscope (SEM), which is known to have the disadvantage that the ability to process samples cannot cope with mass production. Although increasing the electron beam current can improve the yield, but with the increase of the current, the Coulomb Effect (Coulomb Effect) will cause the spatial resolution to be greatly reduced.

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. Electrons from each probe point strike the surface of the sample and thereby generate secondary electrons. Secondary electrons include slow secondary electrons (with energies less than 50 eV) and backscatter electrons (with energies close to the landing energy of electrons). The secondary electrons reflected from multiple small scanning areas can be separately and simultaneously collected by multiple electron detectors. Thus, multi-beam scanning can obtain images of a large viewing area with multiple small scanning areas faster than scanning using a single electron beam.

Multiple electron beams can come from multiple electron sources, respectively, or from a single electron source. For multi-electron sources, multiple electron beams are usually focused and scanned through individual electron cavities (columns), and scan multiple small scanning areas, and the secondary electrons generated from each small scanning area are provided by the corresponding Detected by the electron detector in the electron cavity. Therefore, such devices are often referred to as multi-chamber devices or devices. On the sample surface, the distance between multiple electron beams is 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 means or method having a plurality of beam-limiting openings, and a beamlet-forming beamlet-forming device having multiple electron optical elements. tool or method. The plurality of beam-limiting openings respectively divide a primary-electron beam generated by a single electron source into a plurality of sub-beams or beams. 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 a beam intersection and can be considered as a secondary electron source emitting the corresponding beam. In order to increase the amount of beams, the spacing between the beams is on the order of micrometers. In addition, a one-time projection imaging system and an oblique scanning unit disposed in the electronic chamber are used to respectively project a plurality of first parallel images and scan the plurality of small scanning areas respectively. The secondary electrons generated from the scanning are guided to a secondary projection imaging system by a beam splitter, and then the secondary projection imaging system focuses the secondary electrons to be respectively detected by a plurality of electron detection devices arranged in a single electron cavity. detected by a detection unit. The plurality of detection units can be a plurality of electronic detectors arranged side by side, or a plurality of pixels of an electronic detector. Due to the above characteristics, the above-mentioned device is often referred to as a multi-electron beam device.

The means or method used for beam confinement is typically a conductive plate with a plurality of perforations serving as beam confinement openings. As for the work or method of image formation, each electro-optical element focuses a beam to form a real image (such as US Pat. The beams are deflected to form a virtual image (eg, US Pat. No. 7,244,949 and others in this filed related application). Figures 1 and 2 show two examples from the fifth related application filed in this case. For clarity, only three beams are shown in the figure, and the skew scanning unit, beam splitter, secondary projection 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 enters the electron source conversion unit 120 . The electron source conversion unit 120 comprises a pre-beam bending tool 123 with three pre-bent 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 three electro-optical elements (122_1, 122_2, 122_3). Three pre-bent micro-deflectors (123_1, 123_2, 123_3) respectively deflect the three beams (102_1, 102_2, 102_3) so that they are respectively orthogonal to the three beam limiting openings (121_1, 121_2, 121_3) . And each beam limiting opening ( 121_1 , 121_2 , 121_3 ) serves 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) towards the optical axis 100_1, and form three first virtual images of the electron source 101, namely, Each beam has a virtual crossover. The primary projection imaging system is composed of the objective lens 131 , which focuses the three deflected beams 102_1 - 3 on the surface 7 of the sample 8 , that is, projects three first virtual images on the surface 7 . Thus, the three beams 102_1 - 3 form three detection points ( 102_1 s , 102_2 s , 102_3 s ) on the surface 7 . The current of the detection points (102_1s, 102_2s, 102_3s) can be changed by adjusting the magnification (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 is incident on the beam confinement 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 the position of the movable condenser lens 210 . As shown in FIGS. 1A and 1B , the landing energy (landing energy) of the beams ( 102_1 , 102_2 , 102_3 ) impacting the surface 7 of the sample can be changed by adjusting the potential of the electron source 101 and/or the sample surface 7 .

In a multi-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-FOVs of all beams. Each subfield of view is equal to or smaller than the beam spacing of the sample surface (Ps, FIG. 1A ). To increase productivity, each subfield of view preferably has its imaging resolution selected such that its beam spacing is changed to preserve the subfield's weave. In the case of high image resolutions, smaller sized pixels are used and smaller subfields are required to avoid excessive pixel counts. If it is a low image resolution, a larger pixel size is used and a larger subfield of view is required to improve productivity. Figure 2A shows an example of low image resolution. As indicated by the dotted line in Figure 2A, if the detection points 102_2s and 102_3s can be moved to the right and left respectively, the beam spacing Ps will be changed from P1 to P2, and the total field of view will be increased from 3×P1 to 3×P2, resulting in an increase in productivity . Therefore, making the beam spacing Ps selectable would be a preferred function.

Continuous scan mode (a sample continuously moved such that it is orthogonal to a scan direction of a primary electron beam) is a known method to increase the productivity of conventional single beam setups. If this approach is used in a multi-beam setup, it is desirable to match the overall field of view, or orientation of the array of detection points, to the direction of stage movement. If you have a magnetic lens in a primary projection imaging system, its magnetic field will rotate the beam and therefore the overall field of view, which is well known. As the magnetic field changes with viewing conditions such as landing energy and current across multiple beams, the rotation angle of the overall field of view also changes. FIG. 2B shows an example where 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_1~102_3 is changed from 1 keV to 2 keV, the detection points 102_2S and 102_3S will rotate an angle θ around the optical axis 100_1 indicated by the dotted line. The change in orientation of the total field of view impacts the characteristics of the continuous scan mode. Making the orientation of the probe point array consistent or selectable provides more flexibility to improve productivity and is therefore a preferred function.

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

The present invention will provide methods or apparatus for accomplishing the desired functions described above, practiced in the form of multiple electron beam apparatuses, particularly those implemented in the related applications filed in this application, 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, announcement number US 6,943,349, application date April 2001, inventor Pavel Adanec et al.

(2) US patent application, announcement number US 7,244,949, application date March 2006, inventor Ranier Knippelmeyer et al.

(3) US patent application, application number 15/065,342, filing date March 2016, inventor Weiming Ren et al.

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

(5) US patent application, application number 15/150,858, filing 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 number 15/365,145, filing date in November 2016, inventor Weiming Ren et al.

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

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, which includes an electron source, a condenser lens, an electron source conversion unit, an objective lens, and a deflection 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 under the condenser lens. The object 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 lens. 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 confining tool with a plurality of beam confining openings, and an image forming tool with a plurality of electron optical elements, the image forming tool is movable along an optical axis. The electron source generates a primary electron beam along the optical axis, and the condenser lens focuses the primary electron beam. Multiple beams of the primary electron beam respectively pass through the beam limiting openings and are deflected toward the optical axis by the electron optical elements to respectively form a plurality of virtual images of the electron source. 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, and 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 detection element therefore provides an image signal corresponding to one scanning area.

In an 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 deviation of the plurality of detection points. By moving the image forming tool along the optical axis, the spacing between a plurality of 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 optional, and the orientations of the detection points can be changed by changing the zoom ratio of the magnetic lens and the electrostatic lens.

In one embodiment, the deflection angle in the multiple charged particle beam device can ensure that the plurality of beams land on the surface in a direction normal or substantially normal to the surface. The deflection angle ensures that the beams land on the surface at a specific angle. The skew scanning unit is located on a front focus plane of the objective lens. The skew scan unit tilts the plurality of beams so that each beam lands on the surface at the same or substantially the same landing angle. The multiple charged particle beam device 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, which includes an electron source, a condenser lens, an electron source conversion unit, an objective lens, and a deflection 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 under 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 lens. 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 confining tool having a plurality of beam confining openings, a first image forming tool having a plurality of first electron optical elements, and a second image forming tool having a plurality of second electron optical elements A forming tool, the second image forming tool is located below 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. Multiple beams of the primary electron beam respectively pass through the beam limiting openings and are deflected toward the optical axis by the electron optical elements to respectively form a plurality of virtual images of the electron source. 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, and 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 detection element therefore provides an image signal corresponding to one scanning area.

In an embodiment, the deflection angles of the plurality of beams caused by the active image forming tool in the multi-charged particle beam device are respectively set to reduce the off-axis deviation of the plurality of detection points. By switching between the first image forming tool and the second shadow forming tool to the active image forming tool, the distances between the plurality of 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 ratio of the magnetic lens and the electrostatic lens, the orientations of a plurality of detection points can be changed.

In one embodiment, the deflection angle in the multiple charged particle beam device can ensure that the plurality of beams land on the surface in a direction normal or substantially normal to the surface. The deflection angle ensures that the beams land on the surface at a specific angle. The skew scanning unit is located on a front focus plane of the objective lens. The skew scan unit tilts the plurality of beams so that each beam lands on the surface at the same or substantially the same landing angle. The multiple charged particle beam device 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, including an electron source, a condenser lens, an electron source conversion unit, an objective lens, a deflection 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 under 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 lens. 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 arranged on 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, and the sample The surface of the lens faces the objective. The electron source conversion unit includes a beam confinement tool with a plurality of beam confinement openings, and an image forming tool with 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. Multiple beams of the primary electron beam respectively pass through the beam limiting openings and are deflected toward the optical axis by the electron optical elements to respectively form a plurality of virtual images of the electron source. 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, and 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 detection element therefore provides an image signal corresponding to one scanning area.

In an 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 deviation of the plurality of detection points. By moving the first principle plane along the optical axis, the spacing between the plurality of detection points can be adjusted together.

In one embodiment, the deflection angle in the multiple charged particle beam device can ensure that the plurality of beams land on the surface in a direction normal or substantially normal to the surface. The deflection angle ensures that the beams land on the surface at a specific angle. The skew scanning unit is located on a front focus plane of the objective lens. The skew scan unit tilts the plurality of beams so that each beam lands on the surface at the same or substantially the same landing angle. The multiple charged particle beam device 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 the surface does not undergo electrical breakdown. The potential of the field moving electrodes is set to move the electrostatic field to move the first principle plane. The orientations of the plurality of detection points can be changed by changing the potential of the field electrode and/or the field moving electrode. 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 ratio of the upper magnetic lens and the lower magnetic lens. By setting the polarity of the upper magnetic lens and the lower magnetic lens, the orientations of a plurality of detection points can be changed.

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, including 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 under 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 lens 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 lens. 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 confinement tool with a plurality of beam confinement openings, and an image forming tool with 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. A plurality of beams of the primary electron beam respectively pass through the beam limiting openings, and are deflected by the electron optical elements to be directed toward the optical axis, so as to respectively form a plurality of first virtual images of the electron source. 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 directs the plurality of beams curved, 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, and 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 within the area. The plurality of detection points respectively generate a plurality of secondary electron beams from the plurality of scanning areas, and 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 detection element therefore provides an image signal corresponding to one scanning area.

In an embodiment, the bending angles of the multiple beams caused by the field lens in the multiple charged particle beam device are respectively set to reduce the off-axis deviation of the multiple detection points. The deflection angles of the plurality of beams caused by the plurality of optical and electronic components are respectively set to adjust the distance between the plurality of detection points. The objective lens includes a first magnetic lens and a first electrostatic lens. By changing the zoom ratio of the first magnetic lens and the first electrostatic lens, the orientations 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 ratio of the third magnetic lens and the third electrostatic lens, the orientations of the plurality of detection points can be changed.

In one embodiment, the deflection angle and bending angle of the plurality of beams caused by the plurality of optical elements in the above-mentioned multi-charged particle beam device can ensure that the plurality of beams are perpendicular or substantially perpendicular to the surface. direction to land on the surface. The deflection and bending angles of the beams due to the optical elements ensure that the beams land on the surface at a specific angle. The skew scanning unit is located on a front focus plane of the objective lens. The skew scan unit tilts the plurality of beams so that each beam lands on the surface at the same or substantially the same landing angle. The multiple charged particle beam device 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 method configured in a multi-charged particle beam device for observing a surface of a sample, comprising the following steps: configuring an image forming tool of an electron source conversion unit, which can be along moving an optical axis; forming a plurality of virtual images of an electron source with the image forming tool; imaging the 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 distance between the plurality of detection points.

According to the above purpose, 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: configuring a device having 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 moved along the multiple charged particle beam device the radial movement of 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 removed; the active image forming tool The forming tool respectively forms a plurality of virtual images of the electron source; uses an objective lens to image the plurality of virtual images on the surface and forms a plurality of detection points on the surface; and changes the active image forming tool to the first image forming tool or the second image forming tool to change the distance between the plurality of detection points.

According to the above purpose, 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: configuring an objective lens with a first principle plane, the objective lens can be moved along An optical axis movement of a multi-charged particle beam device; 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 by the objective lens and on the surface forming a plurality of detection points; and moving the first principle plane to change the distance between the plurality of detection points.

According to the above purpose, 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: configuring a multi-charged particle beam device with a lower magnetic lens and a An objective lens of an electrostatic lens; 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 by the objective lens and a plurality of detection points are formed on the surface; And changing a ratio of the zoom ratio of the lower magnetic lens and the electrostatic lens to select an azimuth 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 polarity of the upper magnetic lens and the lower magnetic lens to change the orientation of the detection point.

According to the above purpose, 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: using an image processing tool of an electron source conversion unit to convert an electron source to A plurality of beams are deflected to form a plurality of first virtual images of the electron source; an objective lens is used to image the plurality of first virtual images on the surface and form 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 makes the plurality of beams 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 amount by changing the deflection angle. In one embodiment, the above method further includes a step of using the tilt scanning unit to tilt the plurality of beams to change the landing angle by the same amount. In one embodiment, the above method further includes a step of using a beam tilting deflector to tilt the plurality of beams to change the landing angles of the plurality of beams by the same amount.

According to the above purpose, 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: using an image processing tool of an electron source conversion unit to convert an electron source to 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 form a plurality of second real images; a field lens It is arranged on the intermediate image plane to bend the plurality of beams; and an objective lens is used to image a plurality of second real images on the surface and form a plurality of detection points on the surface.

In one embodiment, the above method further includes a step of changing the deflection angles of the plurality of beams caused by the image forming tool to change the distance between the plurality of detection points. 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 and the bending angle of the plurality of beams caused by the field lens, so that the plurality of beams have the same or substantially The same landing angle lands on the surface. In one embodiment, the above method further includes a step of changing the tilt angles to change the landing angles of the plurality of beams by the same amount. In one embodiment, the above method further includes a step of using a deflection scanning unit to deflect the deflection angles of the plurality of beams by an equal amount. In one embodiment, the above method further includes a step of using a beam tilting deflector to deflect the plurality of beams by an equal amount of deflection angles. 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 a step of changing the zoom 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 method further includes a step of configuring a conversion lens having a second magnetic lens and a second electrostatic lens. In one embodiment, the above method further includes a step of selecting an orientation of the plurality of detection points by changing the zoom ratio of the second magnetic lens and the second electrostatic lens. In one embodiment, the method further includes a step of configuring a field lens having a third magnetic lens and a third electrostatic lens. In one embodiment, the above method further includes a step of selecting an orientation of the plurality of detection points by changing the zoom ratio of the third magnetic lens and the third electrostatic lens.

According to the above purpose, an embodiment of the present invention provides a device including a particle source, a particle source conversion unit, and an objective lens. The particle source is used to provide a beam of primary charged particles. 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 plurality of charged particle beams on the surface is adjusted by changing the tilt angle of the plurality of charged particle beams before entering the objective lens.

According to the above purpose, an embodiment of the present invention provides a device, including 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 lens 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 lens for adjusting the distance between the plurality of detection points on the surface Spacing tool.

According to the above purpose, 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 with a plurality of intersections; projecting the plurality of intersections on the sample surface, so that forming a plurality of detection points; scanning the plurality of detection points on the surface of the sample; and changing the deflection angle of the plurality of charged particle beams, so that the distance between the plurality of detection points is adjusted.

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

Various embodiments of the present application will be described in detail below, and the accompanying drawings are used as examples. By way of illustration and not limitation, the drawings and descriptions are based on electron beams as an example. However, in other embodiments of the invention, other charged particle beams may also be used.

In the drawings, for the sake of clarity, the size of elements may be drawn exaggeratedly, and elements may not be shown in proportion to each other. The same or similar component symbols in the drawings represent the same or similar components, and only the differences between individual components 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, as long as they are not mutually exclusive, they all belong to the concept of the present invention , belonging to the scope of the present invention. The detailed descriptions made in the embodiments of the present invention are for illustration rather than limitation.

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

In this specification, "an imaging system is aligned with an optical axis" means that all electro-optical components, such as round lenses or multipole lenses, are aligned with the optical axis.

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

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

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

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

Based on some multiple electron beam devices proposed in related applications of this application, the present invention proposes a new multiple charged particle beam device with a variable overall field of view (FOV). Among other things, the total field of view of the new multi-charged particle beam device can be changed in size, orientation, and illumination angle. In order to express the method of this application clearly, this embodiment takes the multi-electron beam device of FIG. 1B as an example. 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. Also, one of the three beams is on-axis, but in other embodiments all three beams can be off-axis. Furthermore, elements that are not relevant to the invention, such as the skew scanning unit and the beam splitter, are not shown in the drawing, nor are they 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 conventional multiple electron beam arrangement, multiple beams are deflected toward the optical axis using an image forming tool. The deflection angles of the plurality of beams are set such that the off-axis deviation of the plurality of detection points due to the objective lens is minimized. Therefore, a plurality of deflected beams usually pass through or approach the front focal point (front focal point) of the objective lens, that is, form an on-axis crossing ( 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 lens. 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 deflection angles α2 and α3 of the two off-axis beams 102_2 and 102_3 can be set so 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 usually pass through or approach the front focus of the objective lens 131 , that is, form a 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

.

Fig. 3A, Fig. 4A and Fig. 5A show an embodiment in which multiple charged particle beam devices 300A, 400A, 500A adjust the distance between detection points by changing the deflection angle according to an embodiment of the present invention, and Fig. An embodiment of focal length adjustment detection point spacing. As shown in FIG. 3A , the electron source conversion unit 320 of the multiple charged particle beam device 300A includes a beam confinement tool 121 having three beam confinement openings 121_1 , 121_2 , 121_3 . The electron source conversion unit 320 further 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 move 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, it will become smaller.

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。 FIG. 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 condensing lens 210 collimates the primary electron beam 102 within a variation range 210_2 so that it enters the electron source conversion unit 320 at normal incidence. The beam limiting openings 121_1 , 121_2 , 121_3 split the electron source into an on-axis beam 102_1 and two off-axis beams 102_2 , 102_3 . The two off-axis electro-optical elements 322_2 , 322_3 respectively deflect the beams 102_2 , 102_3 towards the optical axis 300_1 . The objective lens 131 focuses the three radiation beams 102_1 , 102_2 , 102_3 on the surface 7 of the sample 8 so that three detection points 102_1 s , 102_1 s , 102_3 s are respectively formed. The deflection angles α2 and α3 of the beams 102_2 and 102_3 are respectively 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 , ie intersect 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 in FIG. 3C is at the position D2 close to the objective lens 131 instead of the position D1. Therefore, the deflection 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 in FIG. 3B .

Compared with the conventional technology in FIG. 1B , as shown in FIG. 4A , the electron source conversion unit 420 of the multi-charged particle beam device 400A of this embodiment further includes an image forming tool 124, which has three electron optical elements 124_1, 124_2, 124_3 . The image forming tool 124 is located below the image forming tool 122 and can move in the radial direction; therefore, the electron source conversion unit 420 has two operation modes. As shown in FIG. 4B, in the first mode, the image forming tool 122 is used to form 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 in the second mode. Therefore, the two intervals of the three detection points in the second mode are larger than the two intervals in the first mode.

As shown in FIG. 5A , compared with the multi-electron beam device in 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. Fig. 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 enters the electron source conversion unit 220 at normal incidence. The beam limiting openings 121_1 , 121_2 , 121_3 split the primary electron beam into one on-axis beam 102_1 , and two off-axis beams 102_2 and 102_3 . Two off-axis electro-optical elements 122_2 and 122_3 respectively deflect the beams 102_2 and 102_3 towards the optical axis 500_1 . Then three first virtual images of the single electron source are formed. Then the conversion lens 533 focuses the three beams 102_1 , 102_2 , 102_3 on the intermediate image plane PP1 , that is, 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. The field lens 534 is located on the intermediate image plane PP1 and turns the off-axis beams 102_2 and 102_3 towards the optical axis 500_1 without affecting their focus. Afterwards, the objective lens 131 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, 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 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 approach the front focus of the objective lens 131 , ie form an intersection 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, and 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, which due to the electro-optical elements 122_2 and 122_3 vary with the deflection angles α2 and α3 of the beams 102_2 and 102_3 Change. Therefore, the two distances 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 those of Fig. 5B, so that the two off-axis detection points 102_2s and 102_3s are moved from the original dotted line position (Fig. 5B) to the present The position shown in FIG. 5C causes the two intervals 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. When 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 toward the surface 7 . In addition, as the first focusing plane moves downward, the deflection angles of the plurality of beams become smaller; thus, the spacing between the plurality of detection points becomes smaller.

FIG. 6B and FIG. 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 and the deflection angles α2 and α3 of the beams 102_2 and 102_3 of FIG. 6B are smaller than the first focal length f and the deflection angles α2 and α3 of the beams 102_2 and 102_3 of FIG. 6C . As shown in FIG. 6C , the detection points 102_2 s and 102_3 s move 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 a conventional multi-electron beam device is an electromagnetic compound lens. The objective consists of a magnetic lens and an electrostatic lens, and operates in a delay mode (the landing energy of electrons is lower than that of electrons passing through the objective) due to low geometrical 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 a magnetic pole 131_mp1 , a field control electrode 131_e1 and a 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 that no electrical breakdown occurs on the surface 7, reduce the geometric aberration of multiple detection points, control the charge on the surface 7 by reflecting part 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. Therefore, the conventional objective lens can hardly be controlled electrically, that is, changing the potential of the electrodes and/or changing the excitation current of the coil to make it move.

According to the conventional objective lens 131-1 in FIG. 1C, the present invention provides three novel movable objective lenses 631-1, 631-2, and 631-3 in FIGS. 7A, 7B and 7C, respectively. As shown in FIG. 7A , compared with 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 called a field moving electrode.

As shown in FIG. 7B , compared with 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 located on the field control electrode 131_e1 . Therefore, the electrostatic lens is constituted by 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 in FIG. 7A, in the embodiment in 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 and faces 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 called a field moving electrode. Compared with 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 and making the deviation smaller.

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 . Thus, a lower magnetic lens, an upper magnetic lens, and an electrostatic lens are formed. Wherein, the lower magnetic lens generates a lower magnetic field through 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 . The upper magnetic lens generates an upper magnetic field through the magnetic current gap G2 between the magnetic pole 131-3_mp1 and the magnetic pole 631-3_mp3 of the yoke 631-3_y2 through the coil 631-3_c2. The electrostatic lens is composed of a magnetic pole 131_mp1, a field control electrode 131_e1, and a sample 8. The distribution shape of the total magnetic field of the objective lens 631-3 will change with the above-mentioned combination of the upper magnetic field and the lower magnetic field, so 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 at the upper side; at the bottom. The embodiment of FIG. 7C can be combined arbitrarily with the embodiments of FIGS. 7A and 7B to practice more embodiments of the objective lens 631 .

In the following examples, methods of rotating the array of probe points will be presented that can be used to eliminate azimuth variability as observation conditions change the overall field of view, and/or to precisely match the orientation of the sample pattern to the orientation of the array of probe points. As mentioned earlier, the objective lens of a 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 an angle around the optical axis. For example, if the objective lens 131 in FIG. 1A is similar to the objective lens 131-1 in FIG. 1C, the field control electrode 131_e1 can be used to rotate the detection points 102_2s and 102_3s to an angle and control the electric field of the surface 7 of the sample 8. In order to keep the electric field on the surface 7 lower than an allowable value based on the safety of the sample, the potential of the field control electrode 131_e1 can be adjusted within a specific range, for example, 3 kV to 5 kV relative to the sample. The focusing magnification of the electrostatic lens will vary with the potential of the field control electrode 131_e1 , so the focusing magnification of the magnetic lens must be changed to keep multiple beams focused on the surface 7 of the sample 8 . The focus magnification of the magnetic lens changes, causing the rotation angles 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 in FIGS. 3A, 4A, and 5A, if the structure of the objective lens 131 is similar to that of the objective lens 131-1 in FIG. 1C, the angle of the detection point array can be adjusted through this method. For the multi-charged particle beam device 600A of FIG. 6A, if the objective lens 631 has the structure of the objective lens 631-1, 631-2, 631-3 as shown in FIGS. 7A to 7C, the field control electrode 131_e1 and/or the corresponding field movement Electrodes can be used to control the rotation of the array of probing points. For the objective lens 631-3, the orientation of the detection point can be changed by changing the polarity of the magnetic fields of the upper magnetic lens and the lower magnetic lens. 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 power. 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 array of detection points 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 desired 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 the field lens 534 of the multi-charged particle beam 500A provide more possibilities for rotating the array of detection points. FIG. 8A shows a multiple 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. FIG. 8B shows a multiple charged particle beam device 520A according to another embodiment of the present invention, wherein the electromagnetic composite 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. And the electrostatic field of the electrostatic field lens 534_11 can be changed accordingly to generate the required bending angles of multiple beams.

In each of the aforementioned embodiments, the plurality of beams are normal or substantially normal incident on the surface 7 of the sample 8, that is, the angle of incidence or landing angle of the beams (the included angle between the beam and the normal vector of the surface 7) close to zero. In order to effectively observe some patterns of the sample 8, the incident angle is preferably slightly larger than zero. To ensure that multiple beams behave identically, the multiple beams must have the same angle of incidence. To achieve this, the crossover of multiple beams has to 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 how to tilt the multiple beams 102_1 , 102_2 , 102_3 with the image forming tool 122 in the multiple charged particle beam device 100A. The deflection angle α1 of FIG. 1B is zero, while the deflection 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 impinge obliquely on the surface 7 of the sample 8 with the same deflection angle or landing angle. Likewise, the multiple charged particle beam devices 300A, 400A, 500A, and 600A described above can tilt the respective beams with corresponding image forming tools. For the beams 102_1 , 102_2 , 102_3 of the multiple charged particle beam devices 300A, 400A, and 600A, the paths are similar to the paths of the respective beams in FIG. 9A . The paths of the beams of the multi-charged particle beam device 500A are slightly different, as shown in FIG. 9B . The deflection angle α of FIG. 5B is zero, while the deflection angles α1, α2, α3 of the three beams 102_1, 102_2, 102_3 of FIG. 9B offset the 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 multiple charged particle beam device 700 according to another embodiment of the present invention, which utilizes a beam tilting deflector 135 to tilt the beams 102_1 , 102_2 , 102_3 . Compared with FIG. 1B, the beam tilt deflector 135 deflects the beams 102_1, 102_2, and 102_3 at the same time, so that their cross CVs are all moved out of the optical axis, and moved to the first focal plane of the objective lens 131 or close to the first focal plane. face. Likewise, the beam tilt deflector 135 can also be applied to other embodiments of the present invention, such as multiple 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 focusing surface of the objective lens, and preferably, close to the electron source conversion unit. In addition, if the oblique scanning unit of the foregoing embodiments is on the front focal plane of the objective lens, the oblique scanning unit can move the intersection of multiple beams, so the beam oblique deflector 135 is not needed.

Although the multi-charged particle beam device in each embodiment of the present case uses 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 device, a movable image forming tool can be used, and a movable objective lens can also be used. In another embodiment, a movable objective lens, a conversion lens, and a field lens are used. Although the various embodiments use the multi-electron beam device 200A in FIG. 2B as an example, the devices, components and/or methods proposed in the present invention can also be applied to other conventional multi-electron beam devices, such as the multi-electron beam device in FIG. 1A , These modified embodiments all belong to the scope of the present invention.

In conclusion, based on various conventional multi-charged particle beam devices proposed in related applications, the present invention proposes a new multi-charged particle beam device, which includes various methods or elements to make the total field of view of the device have variable 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 particularly, when the novel multi-charged particle device is used as a yield management tool, it is possible to achieve high productivity and detect more types of defects. The present invention proposes three methods to vary the spacing at which the multiple beams are incident on the surface of the sample. These methods include using a movable image forming tool in the electron source conversion unit, or 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 overall field of view is changed. These methods include using an electromagnetic compound objective and varying its electric field, using an objective with two magnetic lenses and setting them so that the two magnetic lenses have opposite polarities, using a magnetic lens and a conversion lens or field lens, or using a magnetic lens plus Conversion lens and field lens. The present invention proposes three methods to move the intersection of multiple beams off the optical axis so that the landing angles of the multiple beams on the surface of the sample are changed in the same way. The deflection of the beams can be done by the image forming tool, or by adding a beam tilt deflector, or by tilting the scanning unit.

The above-mentioned embodiments are only to illustrate the technical ideas and characteristics of the present invention, and its purpose is to enable those familiar with the art to understand the content of the present invention and implement it accordingly, and should not limit the patent scope of the present invention, that is, all other Various equivalent changes or modifications made without departing from the spirit disclosed in the present invention are covered by the scope disclosed in the present invention, and should be included in the scope of the following patent applications.

7: surface 8: Sample 101: Electron source 102: Primary electron beam 110: Concentrating lens 120: Electron source conversion unit 121: Beam Limiting Tool 122:Image forming tool 123:Pre Beam Bending Tool 124:Image forming tool 131: objective lens 131-1: Objective lens 210: Movable condenser lens 210_2: range of change 220: Electron source conversion unit 300:Multiple 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: Multiple Charged Particle Beam Apparatus 102_1: Beam 102_1: Detection point 102_1m: Second real image 102_2: Beam 102_2: Detection point 102_2m: second real image 102_3: Beam 102_3: Detection point 102_3m: second real image 121_1: Electron beam limiting opening 121_2: Electron beam limiting opening 121_3: Electron beam limiting opening 122_1: Electron optical components 122_2: Electron optical components 122_3: Electron optical components 123_1: Pre-curved micro-skewers 123_2: Pre-curved micro-skewers 123_3: Pre-curved micro-deflector 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: Iron yoke 135: Beam Tilt Deviator 300_1: optical axis 300A: Multiple 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: change range 400A: Multiple charged particle beam device 500_1: optical axis 500A: Multiple charged particle beam device 510A: Multiple Charged Particle Beam Apparatus 520A: Multiple Charged Particle Beam Apparatus 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 Lens 600_1: optical axis 600A: Multiple 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: Iron yoke 631-3_c2: Coil 700_1: optical axis 700A: Multiple Charged Particle Beam Apparatus G1: magnetic current spacing G2: magnetic current spacing PP1: intermediate image plane Ps: Spacing α1: skew angle α2: Skew angle α3: Skew angle Gamma 2: Bend angle #3: Bend Angle

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

1A and 1B are schematic diagrams showing the structure of a conventional multi-electron beam device of the fifth application listed in the related prior application of this application.

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

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

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

3B and 3C are schematic diagrams showing the total field of view of variable size and orientation of the multiple 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 device according to another embodiment of the present invention.

4B and 4C are schematic diagrams showing the total field of view of variable size and orientation of the 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 device according to another embodiment of the present invention.

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

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

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

7A to 7C show the structure of the movable objective lens 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 device according to another embodiment of the present invention.

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

FIG. 9B shows the tilt of the multiple charged particle beams of the multiple charged particle beam device 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 device 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 limiting opening

121_2: Electron beam limiting opening

121_3: Electron beam limiting opening

210_2: range of change

300_1: optical axis

300A: Multiple 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: change range

Claims (21)

A source-conversion unit comprising: a beamlet-limit device having a plurality of beamlet-limiting openings configured to allow passage of a plurality of beamlets; and An image forming device movable along a principal optical axis and comprising a plurality of electro-optical elements, wherein at least a part of the plurality of electro-optical elements is configured so that at least a part of the plurality of beams is directed toward 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 principal optical axis forms a plurality of virtual images of an electron source. The source conversion unit as claimed in claim 1 or 2, wherein the at least a portion of the plurality of electro-optical elements is configured to deflect at least a portion of the plurality of beams at a deflection angle to reduce a plurality of detections Off-axis aberrations of probe spots. The source conversion unit as claimed in claim 3, wherein the plurality of detection points have an interval that can be changed together by moving the image forming device along the main optical axis. The source conversion unit as claimed in 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 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 source conversion unit of claim 3, wherein the deflection angles cause the at least a portion of the plurality of beams to obliquely land 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 beam of charged particles along a principal optical axis; A source translation unit comprising: A beam confinement device having beam confinement openings configured to allow passage of beams of the charged particle beam; An image forming device movable along the principal optical axis and comprising a plurality of electro-optical elements, wherein at least a portion of the plurality of electro-optical elements is configured so that at least a portion of the plurality of beams is directed toward the principal optical axis is deflected; 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 according to claim 8, wherein the deflection of at least a part of the plurality of beams toward the principal optical axis forms a plurality of virtual images of the electron source. The multi-beam device as claimed in claim 8 or 9, wherein the objective lens includes a magnetic lens and an electrostatic lens. The multi-beam device as claimed in 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 ratios of the magnetic lens and the electrostatic lens. The multi-beam device as claimed in claim 8 or 9, 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 multi-beam device as claimed in claim 8 or 9, wherein 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 an off angle to reduce the complex number The off-axis aberration of a 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 on a surface of a sample orthogonally or substantially orthogonally. The multi-beam device of claim 13, wherein the deflection angles cause the at least a portion of the plurality of beams to obliquely land on a surface of a sample at the same or substantially the same landing angle. The multi-beam device according to claim 8, further comprising a deflection scanning unit located above a front focal plane of the objective lens. The multi-beam device according to claim 16, wherein the skew scanning unit is configured to tilt the plurality of beams to obliquely land on the surface at the same or substantially the same landing angle. The multi-beam device according to claim 8, further comprising a beam tilt deflector located between the source conversion unit and a front focusing surface of the objective lens. 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 probe 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 according to claim 20, further comprising using an objective lens to form the plurality of detection points on the sample so that the plurality of virtual images are imaged on the surface.

Images