JP7442376B2 - Multi-electron beam inspection device and multi-electron beam inspection method - Google Patents

Description

The present invention relates to a multi-electron beam inspection apparatus and a multi-electron beam inspection method. For example, the present invention relates to an inspection device that performs inspection using a secondary electron image of a pattern emitted by irradiating multiple beams of electron beams.

In recent years, as large-scale integrated circuits (LSIs) have become more highly integrated and have larger capacities, the circuit line width required for semiconductor devices has become increasingly narrower. Improving yield is essential for manufacturing LSIs, which require a large manufacturing cost. However, as typified by 1 gigabit class DRAM (random access memory), the patterns constituting LSIs are on the order of submicrons to nanometers. In recent years, as the dimensions of LSI patterns formed on semiconductor wafers have become smaller, the dimensions that must be detected as pattern defects have also become extremely small. Therefore, there is a need for higher precision pattern inspection equipment that inspects defects in ultrafine patterns transferred onto semiconductor wafers. Another major factor that reduces yield is pattern defects in masks used when exposing and transferring ultra-fine patterns onto semiconductor wafers using photolithography. Therefore, there is a need for higher precision pattern inspection equipment that inspects defects in transfer masks used in LSI manufacturing.

The inspection method is to compare a measurement image of a pattern formed on a substrate such as a semiconductor wafer or lithography mask with design data or a measurement image of the same pattern on a substrate. It has been known. For example, pattern inspection methods include "die to die inspection," which compares measurement image data obtained by capturing images of the same pattern at different locations on the same substrate, and design image inspection based on pattern design data. There is a "die to database inspection" in which data (reference image) is generated and compared with a measurement image that is measurement data obtained by capturing a pattern. The captured image is sent to the comparison circuit as measurement data. After aligning the images, the comparison circuit compares the measurement data and reference data according to an appropriate algorithm, and if they do not match, it is determined that there is a pattern defect.

The above-mentioned pattern inspection apparatus includes a device that irradiates a substrate to be inspected with a laser beam and captures a transmitted or reflected image thereof, as well as a device that scans the substrate to be inspected with a primary electron beam. Progress is also being made in the development of inspection devices that acquire pattern images by detecting secondary electrons emitted from a substrate to be inspected upon irradiation with a secondary electron beam. Among inspection devices that use electron beams, development of devices that use multiple electron beams is also progressing. In an inspection apparatus using multiple electron beams, a sensor is arranged to detect secondary electrons resulting from irradiation with each beam of the multiple primary electron beams, and an image is acquired for each beam. However, since multiple primary electron beams are irradiated simultaneously, there is a problem in that the sensor for each beam is mixed with secondary electrons from other beams, which is so-called crosstalk. Crosstalk becomes a noise factor and deteriorates the image accuracy of the measurement image, which in turn deteriorates the inspection accuracy. In order to avoid crosstalk, it is necessary to reduce the electron energy of the primary electron beam on the sample surface, but this reduces the number of secondary electrons generated. Therefore, in order to obtain the number of secondary electrons necessary for desired image accuracy, it is necessary to lengthen the irradiation time, resulting in deterioration of throughput.

Here, a method has been disclosed in which the interval between the primary electron beams is made larger than the aberration of the secondary optical system in order to eliminate crosstalk between a plurality of secondary electron beams (see, for example, Patent Document 1). .

Japanese Patent Application Publication No. 2002-260571

Accordingly, one aspect of the present invention provides an inspection apparatus and method that can perform inspection with high accuracy even when so-called crosstalk occurs, in which secondary electrons from other beams mix into the sensor of each beam.

A multi-electron beam inspection device according to one embodiment of the present invention includes:
A patterned sample is irradiated with a multi-primary electron beam, and a multi-secondary electron beam emitted due to the irradiation of the sample with the multi-primary electron beam is detected, and crosstalk components are detected. a secondary electron image acquisition mechanism that acquires the included secondary electron image;
a correction unit that generates a corrected secondary electron image in which the crosstalk component is removed from the secondary electron image using preset gain information for removing the crosstalk component from the secondary electron image;
a comparison unit that compares the corrected secondary electron image and a predetermined image;
It is characterized by having the following.

In addition, the secondary electron image acquisition mechanism irradiates the sample with each preset primary electron beam among the multiple secondary electron beams emitted due to the irradiation of the sample with the multiple primary electron beams. It has a multi-detector with multiple sensors arranged to detect the secondary electron beam emitted due to the
For each primary electron beam, an evaluation board different from the sample is irradiated with the primary electron beam, and secondary electron beams emitted due to the irradiation of the evaluation board with the primary electron beam are detects the electron beam,
The primary electron beam detected by a sensor for detecting a secondary electron beam resulting from irradiation of the primary electron beam for each sensor of the plurality of sensors and for each primary electron beam of the multi-primary electron beam. The method further includes a gain calculation unit that calculates, as a gain value, a ratio of the intensity value of the secondary electron beam caused by another primary electron beam detected by the same sensor to the intensity value of the secondary electron beam caused by the irradiation of the sensor. suitable.

Further, as gain information, it further includes an inverse matrix calculation unit that calculates an inverse matrix of a gain matrix whose elements are gain values for each sensor of the plurality of sensors and for each primary electron beam of the multi-primary electron beam,
Preferably, the correction unit generates a corrected secondary electron image from which crosstalk components are removed by multiplying the acquired secondary electron image by an inverse matrix.

Further, it is preferable to further include a beam selection aperture substrate for selecting one primary electron beam from the multiple primary electron beams.

A multi-electron beam inspection method according to one embodiment of the present invention includes:
A sample with a pattern formed thereon is irradiated with multiple primary electron beams, and the multiple secondary electron beams emitted due to the irradiation of the sample with the multiple primary electron beams are detected, and the multiple secondary electron beams containing crosstalk components are detected. a step of acquiring a secondary electron image obtained by
generating a corrected secondary electron image from which crosstalk components are removed from the secondary electron image using preset gain information for removing crosstalk components from the secondary electron image;
Comparing the corrected secondary electron image and a predetermined image and outputting the result;
Equipped with
Using a multi-detector in which a plurality of sensors are arranged, preset primary electrons are detected among the multi-secondary electron beams emitted when the sample is irradiated with the multi-primary electron beams. detecting a secondary electron beam emitted due to the beam irradiating the sample;
For each primary electron beam, an evaluation board different from the sample is irradiated with the primary electron beam, and secondary electron beams emitted due to the irradiation of the evaluation board with the primary electron beam are detects the electron beam,
For each sensor of the plurality of sensors and for each primary electron beam of the multi-primary electron beam, the one detected by the sensor for detecting a secondary electron beam resulting from irradiation of the primary electron beam. calculating the ratio of the intensity value of the secondary electron beam caused by another primary electron beam detected by the same sensor to the intensity value of the secondary electron beam caused by irradiation with the secondary electron beam as a gain value;
as the gain information, calculating an inverse matrix of a gain matrix whose elements are gain values for each sensor of the plurality of sensors and for each primary electron beam of the multi-primary electron beam;
Furthermore,
generating a corrected secondary electron image from which the crosstalk component is removed by multiplying the obtained secondary electron image by the inverse matrix ;
It is characterized by

According to one aspect of the present invention, highly accurate inspection is possible even when so-called crosstalk occurs, in which secondary electrons from other beams mix into the sensor of each beam.

1 is a configuration diagram showing an example of the configuration of a pattern inspection device in Embodiment 1. FIG. 2 is a conceptual diagram showing the configuration of a molded aperture array substrate in Embodiment 1. FIG. 3 is a diagram showing an example of a plurality of chip regions formed on a semiconductor substrate in Embodiment 1. FIG. FIG. 3 is a diagram for explaining a multi-beam scanning operation in the first embodiment. FIG. 3 is a diagram showing an example of the spread of secondary electron beams per primary electron beam in the first embodiment. FIG. 3 is a flowchart showing main steps of the inspection method in the first embodiment. FIG. 3 is a diagram for explaining scanning of a sub-irradiation area and measured secondary electron intensity in Embodiment 1. FIG. 3 is a diagram showing an example of a secondary electron intensity map in Embodiment 1. FIG. 3 is a diagram showing an example of a gain matrix in Embodiment 1. FIG. 5 is a diagram showing an example of a configuration of each gain value in the first embodiment. FIG. 3 is a diagram showing a relational expression between a secondary electronic image P' including a crosstalk image component, a gain matrix G, and a secondary electronic image P not including a crosstalk image component in Embodiment 1. FIG. FIG. 3 is a diagram showing an example of a gain inverse matrix in Embodiment 1. FIG. 3 is a diagram showing a relational expression between a secondary electron image P′ including a crosstalk image component, a gain inverse matrix G ⁻¹ , and a secondary electron image P from which the crosstalk image component has been removed in Embodiment 1. FIG. FIG. 2 is a configuration diagram showing an example of a configuration inside a comparison circuit in Embodiment 1. FIG.

Embodiment 1.
FIG. 1 is a configuration diagram showing an example of the configuration of a pattern inspection apparatus according to the first embodiment. In FIG. 1, an inspection apparatus 100 that inspects a pattern formed on a substrate is an example of a multi-electron beam inspection apparatus. The inspection device 100 includes an image acquisition mechanism 150 (secondary electronic image acquisition mechanism) and a control system circuit 160. The image acquisition mechanism 150 includes an electron beam column 102 (electron lens barrel) and an examination chamber 103. Inside the electron beam column 102, there are an electron gun 201, an electromagnetic lens 202, a shaping aperture array substrate 203, a beam selection aperture substrate 219, an electromagnetic lens 205, a bulk blanking deflector 212, a limiting aperture substrate 213, an electromagnetic lens 206, and an electromagnetic lens. 207 (objective lens), a main deflector 208, a sub-deflector 209, a beam separator 214, a deflector 218, an electromagnetic lens 224, an electromagnetic lens 226, and a multi-detector 222 are arranged. In the example of FIG. 1, an electron gun 201, an electromagnetic lens 202, a shaping aperture array substrate 203, a beam selection aperture substrate 219, an electromagnetic lens 205, a collective blanking deflector 212, a limiting aperture substrate 213, an electromagnetic lens 206, an electromagnetic lens 207 ( The main deflector 208 and the sub-deflector 209 constitute a primary electron optical system that irradiates the substrate 101 with multiple primary electron beams. The beam separator 214, the deflector 218, the electromagnetic lens 224, and the electromagnetic lens 226 constitute a secondary electron optical system that irradiates the multiple detector 222 with multiple secondary electron beams.

A stage 105 movable at least in the XYZ directions is arranged within the examination room 103. A substrate 101 (sample) to be inspected is placed on the stage 105 . The substrate 101 includes an exposure mask substrate and a semiconductor substrate such as a silicon wafer. When the substrate 101 is a semiconductor substrate, a plurality of chip patterns (wafer die) are formed on the semiconductor substrate. When the substrate 101 is an exposure mask substrate, a chip pattern is formed on the exposure mask substrate. The chip pattern is composed of a plurality of graphic patterns. A plurality of chip patterns (wafer die) are formed on the semiconductor substrate by exposing and transferring the chip pattern formed on the exposure mask substrate a plurality of times onto the semiconductor substrate. The case where the substrate 101 is a semiconductor substrate will be mainly described below. For example, the substrate 101 is placed on the stage 105 with the pattern formation surface facing upward. Further, a mirror 216 is arranged on the stage 105 to reflect a laser beam for laser length measurement irradiated from a laser length measurement system 122 arranged outside the examination room 103. Multi-detector 222 is connected to detection circuit 106 external to electron beam column 102.

In the control system circuit 160, a control computer 110 that controls the entire inspection apparatus 100 controls a position circuit 107, a comparison circuit 108, a reference image creation circuit 112, a stage control circuit 114, a lens control circuit 124, and a blanking circuit via a bus 120. Control circuit 126, deflection control circuit 128, secondary electron intensity measurement circuit 129, gain calculation circuit 130, correction circuit 132, inverse matrix calculation circuit 134, storage device 109 such as a magnetic disk device, monitor 117, memory 118, and printer 119 It is connected to the. The deflection control circuit 128 is also connected to DAC (digital-to-analog conversion) amplifiers 144, 146, and 148. DAC amplifier 146 is connected to main deflector 208 , and DAC amplifier 144 is connected to sub-deflector 209 . DAC amplifier 148 is connected to deflector 218.

Further, the detection circuit 106 is connected to a chip pattern memory 123 and a secondary electron intensity measurement circuit 129. Chip pattern memory 123 is connected to comparison circuit 108. Further, the stage 105 is driven by a drive mechanism 142 under the control of a stage control circuit 114. The drive mechanism 142 includes, for example, a drive system such as a 3-axis (X-Y-θ) motor that drives in the X direction, Y direction, and θ direction in the stage coordinate system, and the stage 105 is movable in the XYθ directions. It has become. For these X motor, Y motor, and θ motor (not shown), for example, a step motor can be used. The stage 105 is movable in the horizontal direction and rotational direction by motors for each of the XYθ axes. Furthermore, the drive mechanism 142 uses, for example, a piezo element or the like to control the stage 105 to be movable in the Z direction (height direction). The moving position of the stage 105 is then measured by the laser length measurement system 122 and supplied to the position circuit 107. The laser length measurement system 122 measures the position of the stage 105 using the principle of laser interferometry by receiving the reflected light from the mirror 216. In the stage coordinate system, for example, the X direction, Y direction, and θ direction are set with respect to a plane perpendicular to the optical axis (electron trajectory center axis) of the multi-primary electron beam.

The electromagnetic lens 202, the electromagnetic lens 205, the electromagnetic lens 206, the electromagnetic lens 207 (objective lens), the electromagnetic lens 224, the electromagnetic lens 226, and the beam separator 214 are controlled by the lens control circuit 124. The collective blanking deflector 212 is composed of two or more electrodes, and each electrode is controlled by the blanking control circuit 126 via a DAC amplifier (not shown). The sub-deflector 209 is composed of four or more electrodes, and each electrode is controlled by the deflection control circuit 128 via the DAC amplifier 144. The main deflector 208 is composed of four or more electrodes, and each electrode is controlled by the deflection control circuit 128 via the DAC amplifier 146. The deflector 218 is composed of four or more electrodes, and each electrode is controlled by the deflection control circuit 128 via the DAC amplifier 148.

In addition, the beam selection aperture substrate 219 has, for example, a passage hole formed in the center through which one beam can pass, and is driven by a drive mechanism (not shown) in a direction perpendicular to the orbit center axis (optical axis) of the multiple primary electron beams. It is configured to be movable in (two-dimensional direction).

A high-voltage power supply circuit (not shown) is connected to the electron gun 201, and an accelerating voltage is applied from the high-voltage power supply circuit between a filament (cathode) (not shown) and an extraction electrode (anode) in the electron gun 201, and another extraction electrode is connected to the electron gun 201. By applying a (Wehnelt) voltage and heating the cathode to a predetermined temperature, a group of electrons emitted from the cathode are accelerated and emitted as an electron beam 200.

Here, FIG. 1 shows a configuration necessary for explaining the first embodiment. The inspection apparatus 100 may normally include other necessary configurations.

FIG. 2 is a conceptual diagram showing the configuration of the molded aperture array substrate in the first embodiment. In FIG. 2, the molded aperture array substrate 203 has a two-dimensional horizontal (x direction) m ₁ column x vertical (y direction) n ₁ stage (m ₁ , n ₁ is an integer of 2 or more, and the other is an integer of 2 or more; Holes (openings) 22 (an integer of 1 or more) are formed at a predetermined array pitch in the x and y directions. The example in FIG. 2 shows a case where 23×23 holes (openings) 22 are formed. Ideally, each hole 22 is formed in a rectangular shape with the same size and shape. Alternatively, they may ideally be circular with the same outer diameter. When a portion of the electron beam 200 passes through each of these plurality of holes 22, m ₁ ×n _one (=N) multi-primary electron beams 20 are formed.

Next, the operation of the image acquisition mechanism 150 in the inspection apparatus 100 will be explained.

An electron beam 200 emitted from an electron gun 201 (emission source) is refracted by an electromagnetic lens 202 and illuminates the entire shaped aperture array substrate 203. As shown in FIG. 2, a plurality of holes 22 (openings) are formed in the shaped aperture array substrate 203, and the electron beam 200 illuminates a region including all the plurality of holes 22. A multi-primary electron beam 20 is formed by each part of the electron beam 200 irradiated to the positions of the plurality of holes 22 passing through the plurality of holes 22 of the shaped aperture array substrate 203. During normal image acquisition, the beam selection aperture substrate 219 is retracted to a position where it does not interfere with the multiple primary electron beams 20.

The formed multi-primary electron beam 20 is refracted by an electromagnetic lens 205 and an electromagnetic lens 206, and is placed at the crossover position of each beam of the multi-primary electron beam 20 while repeating intermediate images and crossovers. The beam passes through a beam separator 214 and advances to an electromagnetic lens 207 (objective lens). Then, the electromagnetic lens 207 focuses the multi-primary electron beam 20 onto the substrate 101. The multi-primary electron beam 20 focused on the substrate 101 (sample) surface by the electromagnetic lens 207 (objective lens) is deflected all at once by the main deflector 208 and the sub-deflector 209. Each beam is applied to a respective irradiation position on the substrate 101. Note that when the entire multi-primary electron beam 20 is deflected all at once by the collective blanking deflector 212, it is displaced from the center hole of the limiting aperture substrate 213 and is shielded by the limiting aperture substrate 213. On the other hand, the multi-primary electron beam 20 that has not been deflected by the collective blanking deflector 212 passes through the center hole of the limited aperture substrate 213, as shown in FIG. Blanking control is performed by turning ON/OFF the collective blanking deflector 212, and ON/OFF of the beam is collectively controlled. In this way, the limited aperture substrate 213 shields the multi-primary electron beam 20 that has been deflected by the collective blanking deflector 212 so as to turn the beam OFF. Then, a multi-primary electron beam 20 for inspection (for image acquisition) is formed by a group of beams that have passed through the limiting aperture substrate 213 and are formed from when the beam is turned on until when the beam is turned off.

When a desired position of the substrate 101 is irradiated with the multi-primary electron beam 20, a beam corresponding to each of the multi-primary electron beams 20 is emitted from the substrate 101 due to the irradiation of the multi-primary electron beam 20. , a bundle of secondary electrons (multiple secondary electron beam 300) including reflected electrons is emitted.

Multi-secondary electron beam 300 emitted from substrate 101 passes through electromagnetic lens 207 and advances to beam separator 214 .

Here, the beam separator 214 generates an electric field and a magnetic field in orthogonal directions on a plane perpendicular to the direction in which the central beam of the multi-primary electron beam 20 travels (electron orbit center axis). The electric field exerts a force in the same direction regardless of the direction in which the electrons travel. On the other hand, a magnetic field exerts a force according to Fleming's left-hand rule. Therefore, the direction of the force acting on the electrons can be changed depending on the direction in which the electrons enter. For the multi-primary electron beam 20 entering the beam separator 214 from above, the force due to the electric field and the force due to the magnetic field cancel each other out, and the multi-primary electron beam 20 travels straight downward. On the other hand, the force due to the electric field and the force due to the magnetic field act in the same direction on the multiple secondary electron beam 300 that enters the beam separator 214 from below, and the multiple secondary electron beam 300 is directed diagonally upward. It is bent and separated from the multi-primary electron beam 20.

The multi-secondary electron beam 300 that is bent diagonally upward and separated from the multi-primary electron beam 20 is further bent by a deflector 218 and projected onto a multi-detector 222 while being refracted by electromagnetic lenses 224 and 226. Ru. The multiple detector 222 detects the projected multiple secondary electron beams 300. The reflected electrons and secondary electrons may be projected onto the multi-detector 222, or the reflected electrons may diverge midway and the remaining secondary electrons may be projected onto the multi-detector 222. The multi-detector 222 has a two-dimensional sensor that will be described later. Then, each secondary electron of the multi-secondary electron beam 300 collides with a corresponding region of the two-dimensional sensor to generate electrons, thereby generating secondary electron image data for each pixel. In other words, the multi-detector 222 has the primary electron beams 10i (i indicates an index) of the multi-primary electron beams 20. For 23×23 multi-primary electron beams 20, i=1 to 529 ), a detection sensor is arranged for each. Then, a corresponding secondary electron beam emitted by irradiation with each primary electron beam 10i is detected. Therefore, each detection sensor of the plurality of detection sensors of the multi-detector 222 detects the intensity signal of the image secondary electron beam resulting from the irradiation of the primary electron beam 10i for which it is responsible. The intensity signal detected by the multi-detector 222 is output to the detection circuit 106.

FIG. 3 is a diagram illustrating an example of a plurality of chip regions formed on a semiconductor substrate in the first embodiment. In FIG. 3, when the substrate 101 is a semiconductor substrate (wafer), a plurality of chips (wafer die) 332 are formed in a two-dimensional array in an inspection area 330 of the semiconductor substrate (wafer). A mask pattern for one chip formed on an exposure mask substrate is reduced to, for example, 1/4 and transferred onto each chip 332 by an exposure device (stepper) not shown. The area of each chip 332 is divided, for example, into a plurality of stripe areas 32 with a predetermined width in the y direction. The scanning operation by the image acquisition mechanism 150 is performed for each stripe area 32, for example. For example, while moving the stage 105 in the −x direction, the scanning operation of the stripe region 32 is relatively progressed in the x direction. Each stripe area 32 is divided into a plurality of frame areas 33 in the longitudinal direction. The movement of the beam to the target frame region 33 is performed by collectively deflecting the entire multi-primary electron beam 20 by the main deflector 208.

FIG. 4 is a diagram for explaining the multi-beam scanning operation in the first embodiment. The example in FIG. 4 shows the case of a 5×5 array of multi-primary electron beams 20. The irradiation area 34 that can be irradiated by one irradiation with the multi-primary electron beam 20 is (x-direction calculated by multiplying the inter-beam pitch in the x-direction of the multi-primary electron beams 20 on the surface of the substrate 101 by the number of beams in the x-direction). size)×(y-direction size obtained by multiplying the inter-beam pitch in the y-direction of the multi-primary electron beams 20 on the surface of the substrate 101 by the number of beams in the y-direction). It is preferable that the width of each stripe area 32 is set to be the same as the y-direction size of the irradiation area 34, or to a size narrower by the scan margin. The examples in FIGS. 3 and 4 show a case where the irradiation area 34 has the same size as the frame area 33. However, it is not limited to this. The irradiation area 34 may be smaller than the frame area 33. Or it doesn't matter if it's big. Each beam of the multi-primary electron beam 20 is irradiated into a sub-irradiation area 29 surrounded by the inter-beam pitch in the x direction and the inter-beam pitch in the y direction, where its own beam is located, and the sub-irradiation area 29 is Scan inside (scanning operation). Each primary electron beam 10 constituting the multi-primary electron beam 20 is responsible for one of the different sub-irradiation areas 29. Then, during each shot, each primary electron beam 10 irradiates the same position within the assigned sub-irradiation area 29. Movement of the primary electron beam 10 within the sub-irradiation area 29 is performed by deflecting the entire multi-primary electron beam 20 at once by the sub-deflector 209. This operation is repeated to sequentially irradiate one sub-irradiation area 29 with one primary electron beam 10. When scanning of one sub-irradiation area 29 is completed, the entire multi-primary electron beam 20 is collectively deflected by the main deflector 208, so that the irradiation position moves to an adjacent frame area 33 within the same stripe area 32. This operation is repeated to sequentially irradiate the inside of the stripe area 32. When scanning of one stripe area 32 is completed, the irradiation position is moved to the next stripe area 32 by moving the stage 105 and/or deflecting the entire multi-primary electron beam 20 at once by the main deflector 208. As described above, a secondary electron image is obtained for each sub-irradiation area 29 by irradiation with each primary electron beam 10i. By combining these secondary electron images for each sub-irradiation area 29, a secondary electron image of the frame area 33, a secondary electron image of the stripe area 32, or a secondary electron image of the chip 332 is constructed.

Note that it is also preferable that, for example, a plurality of chips 332 lined up in the x direction are grouped into the same group, and each group is divided into a plurality of stripe regions 32 with a predetermined width in the y direction, for example. Furthermore, the movement between the stripe regions 32 is not limited to each chip 332, and it is also suitable to move each group.

Here, when the multi-primary electron beam 20 is irradiated onto the substrate 101 while the stage 105 is continuously moving, the main deflector 208 deflects the multi-primary electron beam 20 at once so that the irradiation position follows the movement of the stage 105. Tracking operation is performed by Therefore, the emission position of the multiple secondary electron beams 300 changes every moment with respect to the orbital center axis of the multiple primary electron beams 20. Similarly, when scanning the sub-irradiation area 29, the emission position of each secondary electron beam changes momentarily within the sub-irradiation area 29. The deflector 218 collectively deflects the multiple secondary electron beams 300 so that each of the secondary electron beams whose emission positions have changed in this way is irradiated into the corresponding detection area of the multiple detector 222.

FIG. 5 is a diagram showing an example of the spread of secondary electron beams per primary electron beam in the first embodiment. The example in FIG. 5 shows the case of a 5×5 array of multi-primary electron beams 20. In the multi-detector 222, a plurality of detection sensors 223 corresponding to the number of multi-primary electron beams 20 are arranged two-dimensionally. The plurality of detection sensors 223 are configured such that each of the preset primary electron beams 10 out of the multiple secondary electron beams 300 emitted due to the irradiation of the multiple primary electron beams 20 onto the substrate 101 This is a sensor for detecting the secondary electron beam 12 emitted due to the irradiation of the secondary electron beam 12. However, in order to obtain a desired throughput in the inspection process using the inspection apparatus 100, it is necessary to irradiate the substrate 101 with electron energy corresponding to the throughput. In this case, there is a problem in that the detection sensor 223 of each primary electron beam 10 is mixed with secondary electrons from other primary electron beams 10, which is so-called crosstalk. In the example of FIG. 5, the secondary electron beam 12 that is scheduled to enter the detection sensor 223 in the second row from the left and the fourth row from the bottom ends up having some secondary electrons mixed into other detection sensors 223 around it. Indicates the condition. Although most of the secondary electron beam 12 caused by the irradiation of the primary electron beam 10 is incident on the detection sensor 223 set in advance for the primary electron beam 10, some of the secondary electrons are The beam enters the beam detection sensor 223. As the electron energy of the multi-primary electron beam 20 on the substrate 101 increases, the distribution of secondary electrons becomes wider. In the multi-beam scanning operation, since the multiple primary electron beams 20 are irradiated simultaneously, the secondary electron data detected by the detection sensor 223 for each beam includes 2 This also includes electronic information. Such crosstalk becomes a noise factor and deteriorates the image accuracy of the measurement image.

On the other hand, a reference image used for comparison when inspecting the measurement image is created based on design data that is the basis of the graphic pattern formed on the substrate 101, for example. Therefore, when comparing the measurement image (image to be inspected: secondary electron image) containing the crosstalk image with the reference image created based on the design data, it is found that there is a difference in the image even though it is not a defect. Therefore, a so-called pseudo defect may occur, which is determined to be a defect. In this way, crosstalk degrades inspection accuracy. In order to avoid crosstalk, it is necessary to reduce the electron energy of the primary electron beam 10 on the surface of the substrate 101, but this reduces the number of secondary electrons generated. Therefore, in order to obtain the number of secondary electrons required for desired image accuracy, it is necessary to lengthen the irradiation time, resulting in deterioration of throughput. Therefore, in the first embodiment, the gain matrix of the crosstalk component is determined, and the inverse matrix of the gain is calculated in advance to correct the scanned image with the inverse matrix and remove the crosstalk component. This will be explained in detail below.

FIG. 6 is a flowchart showing the main steps of the inspection method in the first embodiment. In FIG. 6, the inspection method in the first embodiment includes a secondary electron intensity measurement step (S102), a gain calculation step (S104), an inverse matrix calculation step (S108), and a secondary electron image acquisition step (S110). Then, a series of steps are performed: an image correction step (S112), a reference image creation step (S114), an alignment step (S120), and a comparison step (S122).

As the secondary electron intensity measurement step (S102), the secondary electron intensity measurement circuit 129 measures the secondary electron intensity detected by each detection sensor 223 in the multi-detector 222 for each primary electron beam 10 of the multi-primary electron beam 20. Measure electron intensity. Specifically, it operates as follows. First, the beam selection aperture substrate 219 is moved to select one primary electron beam 10 out of the multiple primary electron beams 20 that passes through the passage hole of the beam selection aperture substrate 219 . The other primary electron beam 10 is blocked by the beam selection aperture substrate 219. Then, using this single primary electron beam 10, the sub-irradiation area 29 of the evaluation board is scanned. As described above, the scanning method is such that the irradiation position (pixel) of the primary electron beam 10 is sequentially moved by deflection by the sub-deflector 209. Here, it is sufficient to know the difference in the secondary electron intensity detected by each detection sensor 223 due to irradiation with the same primary electron beam, so for example, the evaluation board 1 on which no pattern is formed is irradiated with the primary electron beam 10. do it. By using the evaluation substrate on which no pattern is formed in this way, it is possible to obtain the effect that the characteristics of each sub-irradiation area are made uniform. However, it is also possible to use the evaluation board 2 on which an evaluation pattern is formed.

FIG. 7 is a diagram for explaining the scanning of the sub-irradiation area and the measured secondary electron intensity in the first embodiment. In FIG. 7, for example, a case is shown in which the sub-irradiation area 29 is scanned with beam 1 of the N×N multi-primary electron beams 20. The sub-irradiation area 29 has a size of, for example, n×n pixels. For example, it is composed of 1000×1000 pixels. It is preferable that the pixel size is approximately the same as the beam size of the primary electron beam 10, for example. However, it is not limited to this. The pixel size may be smaller than the beam size of the primary electron beam 10. Alternatively, the pixel size may be larger than the beam size of the primary electron beam 10, although the resolution of the image will be lower. When each pixel is sequentially irradiated with beam 1, the secondary electron beam resulting from the irradiation of beam 1 onto each pixel is sequentially detected by the detection sensor 223 for beam 1 of the multi-detector 222. If the distribution of the secondary electron beam is wider than the area of the detection sensor 223 for the target beam, as shown in FIG. 5, the secondary electron beam can be sequentially detected by the detection sensor 223 for other beams at the same time. The intensity signals detected by the multi-detector 222 are output to the detection circuit 106 in the order of measurement. Within the detection circuit 106, analog detection data is converted into digital data by an A/D converter (not shown) and output to the secondary electron intensity measurement circuit 129. The secondary electron intensity measurement circuit 129 uses the input intensity signal to measure the secondary electron intensity, which is composed of a map having secondary electron intensities i(1,1) to i(n,n) of each pixel as elements. Measure I(1,1). (a, b) of the secondary electron intensity i(a, b) of each pixel indicates the coordinates of each pixel. a=1 to n, b=one of the values 1 to n.

FIG. 8 is a diagram showing an example of a secondary electron intensity map in the first embodiment. In FIG. 8, A of secondary electron intensity I(A, B), which is an element of the secondary electron intensity map, indicates a beam number and B indicates a detection sensor number. A=1 to N and B=1 to N. By scanning the sub-irradiation area 29 for beam 1 using beam 1, the secondary electron intensities I(1,1) to I(1,N) can be measured. By moving the beam selection aperture board 219 and sequentially selecting the target primary electron beams 10, for example, using beam 2, the secondary electron intensities I(2,1) to I(2,N) can be changed. Using beam 3, secondary electron intensities I(3,1) to I(3,N) can be measured. By similarly measuring using each primary electron beam 10, the secondary electron intensity measurement circuit 129 calculates the secondary electron intensity I(1,1) to I (N, N) can be measured. Information on the measured secondary electron intensities I(1,1) to I(N,N) is output to the gain calculation circuit 130.

As the gain calculation step (S104), the gain calculation circuit 130 calculates a gain value for each detection sensor 223 and for each primary electron beam 10. Specifically, the gain calculation circuit 130 calculates the gain value of the primary electron beam 10 detected by the detection sensor 223 for detecting the secondary electron beam 12 resulting from the irradiation of the primary electron beam 10. The ratio of the intensity value of the secondary electron beam 12 caused by another primary electron beam 10 detected by the same detection sensor 223 to the intensity value of the secondary electron beam 12 caused by the irradiation is calculated.

FIG. 9 is a diagram showing an example of a gain matrix in the first embodiment. In FIG. 9, A of gain values G(A, B) serving as each element of the gain matrix G indicates a beam number. B indicates the detection sensor number. A=1 to N and B=1 to N. The gain value G(m,k) of beam m (primary electron beam) at detection sensor k for beam k (primary electron beam) is defined by the following equation (1).
(1) G(m,k)=I(m,k)/I(k,k)

By calculating the gain value for each detection sensor 223 and each primary electron beam 10, gain values G(1,1) to G(N,N) can be obtained as shown in FIG. Then, a gain matrix having such gain values G(1,1) to G(N,N) as elements can be created. In addition, as is clear from equation (1), the gain values G(1,1), G(2,2), ..., G(N,N) with the same beam number and detection sensor number are Since also becomes 1, the calculation can be omitted.

FIG. 10 is a diagram showing an example of the configuration of each gain value in the first embodiment. As shown in FIG. 7, the secondary electron intensities I(1,1) to I(N,N) are the secondary electron intensities i(1,1) to i(n,n) of each pixel, respectively. Since it is composed of maps as elements, as shown in FIG. It is composed of a map whose elements are n, n). In other words, the gain value may be different for each pixel. Information on the created gain matrix G is stored in the storage device 109.

FIG. 11 is a diagram showing a relational expression between the secondary electronic image P' including the crosstalk image component, the gain matrix G, and the secondary electronic image P not including the crosstalk image component in the first embodiment. . In FIG. 11, a set of secondary electron images P'=(P1', P2', . . . , PN') containing crosstalk image components for each sub-irradiation area 29 of each primary electron beam 10 is as follows: The product of the gain matrix G and the set of secondary electron images P = (P1, P2, ..., PN) that does not include crosstalk image components for each sub-irradiation area 29 of each primary electron beam 10. Can be defined. Briefly stated, the relationship between the secondary electron image P' containing the crosstalk image component, the gain matrix G, and the secondary electron image P not containing the crosstalk image component is defined by the following determinant (2). can.
(2) P'=G・P

Therefore, by determining the gain inverse matrix G ^-1 , which is the inverse matrix of the gain matrix G, the crosstalk image is extracted from the secondary electron image P' containing the crosstalk image component, as shown in the following equation (3). A secondary electron image P containing no components can be obtained.
(3) P=G ^-1・P'

As the inverse matrix calculation step (S108), the inverse matrix calculation circuit 134 (inverse matrix calculation unit) calculates, as gain information, a gain value for each sensor of the plurality of sensors and for each primary electron beam of the multi-primary electron beams. A gain inverse matrix G ⁻¹ (gain information), which is an inverse matrix of this gain matrix G, is calculated from the gain matrix G shown in FIG. 9 whose elements are . A conventional method may be used for the inverse matrix calculation.

FIG. 12 is a diagram showing an example of the gain inverse matrix G ⁻¹ in the first embodiment. In FIG. 12, A of the inverse gain value G ^-1 (A, B) which is each element of the gain inverse matrix G ^-1 indicates a beam number. B indicates the detection sensor number. A=1 to N and B=1 to N. Through such calculation, as ^{shown in} FIG. The matrix G ⁻¹ can be obtained. The gain information of the calculated gain inverse matrix G ⁻¹ is stored in the memory 118 or the storage device 109.

After performing the above steps as pre-processing, the substrate 101 to be inspected is placed on the stage 105, and actual inspection processing is performed.

As the secondary electron image acquisition step (S110), the image acquisition mechanism 150 (secondary electron image acquisition mechanism) irradiates the substrate 101 on which a plurality of graphic patterns are formed with the multi-primary electron beam 20 to obtain the multi-primary electron beam 20. A multi-secondary electron beam 300 emitted due to irradiation of the substrate 101 with the electron beam 20 is detected, and a secondary electron image containing crosstalk components for each sub-irradiation area 29 is acquired. As described above, reflected electrons and secondary electrons may be projected onto the multi-detector 222, or reflected electrons may diverge midway and remaining secondary electrons may be projected onto the multi-detector 222.

As described above, the image is acquired by irradiating the multiple primary electron beams 20 and generating the multiple secondary electron beams 300 containing reflected electrons emitted from the substrate 101 due to the irradiation of the multiple primary electron beams 20. It is detected by the multi-detector 222. The detection data of secondary electrons for each pixel in each sub-irradiation area 29 detected by the multi-detector 222 (measurement image data: secondary electron image data: image data to be inspected) is output to the detection circuit 106 in the order of measurement. Ru. In the detection circuit 106, analog detection data is converted into digital data by an A/D converter (not shown) and stored in the chip pattern memory 123. The obtained measurement image data is then transferred to the correction circuit 132 together with information indicating each position from the position circuit 107. It goes without saying that the secondary electron image data for each pixel obtained here still contains crosstalk image components.

In the image correction step (S112), the correction circuit 132 (correction unit) uses the gain information (gain inverse matrix G ⁻¹ ) stored in the memory 118 or storage device 109 in advance in the inverse matrix calculation step (S108). , a corrected secondary electron image is generated by removing crosstalk components from the secondary electron image. Specifically, the correction circuit 132 multiplies the acquired secondary electron image containing the crosstalk image component for each sub-irradiation area 29 by the gain inverse matrix G ⁻¹ read from the memory 118 or the storage device 109. As a result, a corrected secondary electron image for each sub-irradiation area 29 with crosstalk components removed is generated.

FIG. 13 shows a relational expression between the secondary electron image P′ including the crosstalk image component, the gain inverse matrix G ⁻¹ , and the secondary electron image P from which the crosstalk image component has been removed in the first embodiment. It is a diagram. In FIG. 13, a set of secondary electron images P=(P1, P2, ..., PN) from which crosstalk image components have been removed for each sub-irradiation area 29 of each primary electron beam 10 is a gain inverse matrix G ^-1 and a set of secondary electron images P'=(P1', P2',..., PN') containing crosstalk image components for each sub-irradiation area 29 of each primary electron beam 10. It can be defined as a product. Briefly, the corrected secondary electron image P from which the crosstalk image component has been removed is obtained from the gain inverse matrix G ⁻¹ and the secondary electron image P' containing the crosstalk image component according to equation (3). You can ask for it. The corrected image data of the corrected secondary electronic image P is transferred to the comparison circuit 108 together with information indicating each position from the position circuit 107.

As the reference image creation step (S114), the reference image creation circuit 112 creates a reference image corresponding to the mask die image based on the design data that is the basis of the plurality of graphic patterns formed on the substrate 101. Specifically, it operates as follows. First, design pattern data is read from the storage device 109 through the control computer 110, and each graphic pattern defined in the read design pattern data is converted into binary or multivalued image data.

As mentioned above, the shapes defined in the design pattern data are basic shapes such as rectangles and triangles, and include the coordinates (x, y) at the reference position of the shape, the length of the sides, rectangles, triangles, etc. Graphic data is stored that defines the shape, size, position, etc. of each pattern graphic using information such as a graphic code serving as an identifier for distinguishing the graphic type.

When design pattern data serving as such graphic data is input to the reference image creation circuit 112, it is developed into data for each graphic, and the graphic code, graphic dimensions, etc. indicating the graphic shape of the graphic data are interpreted. Then, it is expanded into binary or multivalued design pattern image data as a pattern arranged in a grid with a grid of a predetermined quantization size as a unit, and output. In other words, read the design data, calculate the occupancy rate occupied by the figure in the design pattern for each square created by virtually dividing the inspection area into squares with predetermined dimensions as units, and calculate the n-bit occupancy data. Output. For example, it is preferable to set one square as one pixel. If one pixel has a resolution of ^1/28 (=1/256), a small area of 1/256 is allocated for the area of the figure placed within the pixel, and the occupancy rate within the pixel is calculated. calculate. This results in 8-bit occupancy data. Such squares (inspection pixels) may be aligned with pixels of measurement data.

Next, the reference image creation circuit 112 performs filter processing on the design image data of the design pattern, which is the image data of the figure, using a predetermined filter function. Thereby, the design image data, which is image data on the design side in which the image intensity (gradation value) is a digital value, can be matched to the image generation characteristics obtained by irradiation with the multi-primary electron beam 20. The image data for each pixel of the created reference image is output to the comparison circuit 108.

FIG. 14 is a configuration diagram showing an example of the internal configuration of the comparison circuit in the first embodiment. In FIG. 14, storage devices 52 and 56 such as magnetic disk devices, an alignment section 57, and a comparison section 58 are arranged in the comparison circuit 108. Each "section" such as the alignment section 57 and the comparison section 58 includes a processing circuit, and the processing circuit includes an electric circuit, a computer, a processor, a circuit board, a quantum circuit, a semiconductor device, or the like. Further, each "~ section" may use a common processing circuit (the same processing circuit). Alternatively, different processing circuits (separate processing circuits) may be used. Input data or calculated results required in the alignment section 57 and the comparison section 58 are stored in a memory (not shown) or in the memory 118 each time.

In the first embodiment, the sub-irradiation area 29 obtained by the scanning operation of one primary electron beam 10i is further divided into a plurality of mask die areas, and the mask die area is used as a unit area of the image to be inspected. Note that each mask die area is preferably configured so that the margin areas overlap each other so that there is no image omission.

In the comparison circuit 108, the transferred corrected secondary electron image data is temporarily stored in the storage device 56 as a mask die image (image to be inspected) for each mask die area. The similarly transferred reference image data is temporarily stored in the storage device 52 as a reference image for each mask die area.

As the positioning step (S120), the positioning unit 57 reads out the mask die image serving as the image to be inspected and the reference image corresponding to the mask die image, and positions both images in units of subpixels smaller than pixels. For example, alignment may be performed using the least squares method.

As a comparison step (S122), the comparison unit 58 compares the mask die image (corrected secondary electron image) and the reference image (an example of a predetermined image). In other words, the comparison unit 58 compares the reference image data and the corrected secondary electronic image data from which the crosstalk image component has been removed, pixel by pixel. The comparison unit 58 compares the two pixel by pixel according to predetermined determination conditions, and determines whether there is a defect such as a shape defect, for example. For example, if the gradation value difference for each pixel is larger than the determination threshold Th, it is determined that the pixel is defective. Then, the comparison result is output. The comparison result may be outputted to the storage device 109, monitor 117, or memory 118, or outputted from the printer 119.

In the above example, a case was explained in which a die database check was performed, but the present invention is not limited to this. Since the crosstalk image component has been removed from the image to be inspected, die-to-die inspection may be performed. A case of performing a die-to-die inspection will be explained.

As the positioning step (S120), the positioning unit 57 reads out the mask die image of die 1 (corrected image to be inspected) and the mask die image of die 2 on which the same pattern is formed (corrected image to be inspected), and Both images are aligned in small sub-pixel units. For example, alignment may be performed using the least squares method.

As a comparison step (S122), the comparison unit 58 compares the mask die image of die 1 (corrected image to be inspected) and the mask die image of die 2 (corrected image to be inspected). The comparison unit 58 compares the two pixel by pixel according to predetermined determination conditions, and determines whether there is a defect such as a shape defect, for example. For example, if the gradation value difference for each pixel is larger than the determination threshold Th, it is determined that the pixel is defective. Then, the comparison result is output. The comparison result is output to storage device 109, monitor 117, or memory 118.

As described above, according to the first embodiment, even when so-called crosstalk occurs, in which the sensor of each beam is mixed with secondary electrons from other beams, inspection can be performed with high accuracy.

In the above description, a series of "circuits" includes a processing circuit, and the processing circuit includes an electric circuit, a computer, a processor, a circuit board, a quantum circuit, a semiconductor device, and the like. Further, each "circuit" may use a common processing circuit (the same processing circuit). Alternatively, different processing circuits (separate processing circuits) may be used. A program for executing a processor or the like may be recorded on a recording medium such as a magnetic disk device, a magnetic tape device, an FD, or a ROM (read only memory). For example, the position circuit 107, the comparison circuit 108, the reference image creation circuit 112, the stage control circuit 114, the lens control circuit 124, the blanking control circuit 126, the deflection control circuit 128, the secondary electron intensity measurement circuit 129, the gain calculation circuit 130, The correction circuit 132 and the inverse matrix calculation circuit 134 may be configured with at least one processing circuit described above.

The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. The example in FIG. 1 shows a case where a multi-primary electron beam 20 is formed by a shaping aperture array substrate 203 from one beam irradiated from an electron gun 201 serving as one irradiation source, but the present invention is not limited to this. isn't it. An embodiment may be adopted in which the multi-primary electron beam 20 is formed by irradiating primary electron beams from a plurality of irradiation sources, respectively.

In addition, descriptions of parts not directly necessary for the explanation of the present invention, such as the device configuration and control method, have been omitted, but the necessary device configuration and control method can be selected and used as appropriate.

In addition, all multi-electron beam inspection apparatuses and multi-electron beam inspection methods that include the elements of the present invention and whose designs can be appropriately modified by those skilled in the art are included within the scope of the present invention.

10 Primary electron beam 12 Secondary electron beam 20 Multi-primary electron beam 22 Hole 29 Sub-irradiation area 32 Stripe area 33 Frame area 34 Irradiation area 52, 56 Storage device 57 Alignment section 58 Comparison section 100 Inspection device 101 Substrate 102 Electron Beam column 103 Examination room 105 Stage 106 Detection circuit 107 Position circuit 108 Comparison circuit 109 Storage device 110 Control computer 112 Reference image creation circuit 114 Stage control circuit 117 Monitor 118 Memory 119 Printer 120 Bus 122 Laser length measurement system 123 Chip pattern memory 124 Lens Control circuit 126 Blanking control circuit 128 Deflection control circuit 129 Secondary electron intensity measurement circuit 130 Gain calculation circuit 132 Correction circuit 134 Inverse matrix calculation circuit 142 Drive mechanism 144, 146, 148 DAC amplifier 150 Image acquisition mechanism 160 Control system circuit 200 Electronics Beam 201 Electron gun 202 Electromagnetic lens 203 Shaped aperture array substrate 205, 206, 207, 224, 226 Electromagnetic lens 208 Main deflector 209 Sub deflector 212 Collective blanking deflector 213 Limiting aperture substrate 214 Beam separator 216 Mirror 218 Deflector 219 Beam selection aperture board 222 Multi-detector 223 Detection sensor 300 Multi-secondary electron beam 330 Inspection area 332 Chip

Claims (3)

A patterned sample is irradiated with a multi-primary electron beam, and a multi-secondary electron beam emitted due to the irradiation of the sample with the multi-primary electron beam is detected, and crosstalk components are detected. a secondary electron image acquisition mechanism that acquires a secondary electron image containing;
a correction unit that generates a corrected secondary electron image in which the crosstalk component is removed from the secondary electron image using preset gain information for removing the crosstalk component from the secondary electron image;
a comparison unit that compares the corrected secondary electron image and a predetermined image;
Equipped with
The secondary electron image acquisition mechanism is configured such that each of preset primary electron beams among the multiple secondary electron beams emitted due to the irradiation of the multiple primary electron beams onto the sample It has a multi-detector in which multiple sensors are arranged to detect the secondary electron beam emitted due to irradiation with the
For each primary electron beam, an evaluation board different from the sample is irradiated with the primary electron beam, and secondary electron beams emitted due to the irradiation of the evaluation board with the primary electron beam are detects the electron beam,
For each sensor of the plurality of sensors and for each primary electron beam of the multi-primary electron beam, the one detected by the sensor for detecting a secondary electron beam resulting from irradiation with the primary electron beam. a gain calculation unit that calculates, as a gain value, a ratio of the intensity value of the secondary electron beam caused by another primary electron beam detected by the same sensor to the intensity value of the secondary electron beam caused by irradiation with the secondary electron beam; ,
an inverse matrix calculation unit that calculates, as the gain information, an inverse matrix of a gain matrix whose elements are gain values for each sensor of the plurality of sensors and for each primary electron beam of the multi-primary electron beam;
Furthermore,
The correction unit generates a corrected secondary electron image from which the crosstalk component is removed by multiplying the acquired secondary electron image by the inverse matrix .
A multi-electron beam inspection device characterized by: 2. The multi-electron beam inspection apparatus according to claim 1 , further comprising a beam selection aperture substrate for selecting one primary electron beam from the multiple primary electron beams. A patterned sample is irradiated with a multi-primary electron beam, and a multi-secondary electron beam emitted due to the irradiation of the sample with the multi-primary electron beam is detected, and crosstalk components are detected. a step of acquiring a secondary electron image containing;
generating a corrected secondary electron image in which the crosstalk component is removed from the secondary electron image using preset gain information for removing the crosstalk component from the secondary electron image;
Comparing the corrected secondary electron image and a predetermined image and outputting the result;
Equipped with
Using a multi-detector in which a plurality of sensors are arranged, preset primary electrons are detected among the multi-secondary electron beams emitted when the sample is irradiated with the multi-primary electron beams. detecting a secondary electron beam emitted due to the beam irradiating the sample;
For each primary electron beam, an evaluation board different from the sample is irradiated with the primary electron beam, and secondary electron beams emitted due to the irradiation of the evaluation board with the primary electron beam are detects the electron beam,
For each sensor of the plurality of sensors and for each primary electron beam of the multi-primary electron beam, the one detected by the sensor for detecting a secondary electron beam resulting from irradiation with the primary electron beam. calculating a ratio of the intensity value of the secondary electron beam caused by another primary electron beam detected by the same sensor to the intensity value of the secondary electron beam caused by the irradiation of the secondary electron beam as a gain value;
as the gain information, calculating an inverse matrix of a gain matrix whose elements are gain values for each sensor of the plurality of sensors and for each primary electron beam of the multi-primary electron beam;
Furthermore,
generating a corrected secondary electron image from which the crosstalk component is removed by multiplying the obtained secondary electron image by the inverse matrix ;
A multi-electron beam inspection method characterized by:

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