Electron beam adjustment method, multi-electron beam position evaluation method, and electron beam image acquisition device

Abstract

This invention provides a method for adjusting an electron beam that can bring the beam size irradiated onto the sample surface closer to an optimal state. [Configuration] An electron beam adjustment method according to one aspect of the present invention is characterized by comprising the steps of: scanning a sample with a primary electron beam; detecting a secondary electron beam emitted from the sample due to scanning; obtaining parameters from a secondary electron image using a secondary electron image obtained from the detection result of the secondary electron beam; and adjusting the incidence angle of the primary electron beam onto the sample using the parameters.

Description

[Technical Field]

[0001] The present invention relates to an electron beam adjustment method, a multi-electron beam position evaluation method, and an electron beam image acquisition apparatus. For example, the present invention relates to an electron beam adjustment method for acquiring a pattern image using a secondary electron image caused by irradiation of multiple primary electron beams. [Background Art]

[0002] In recent years, along with the higher integration and larger capacity of large-scale integrated circuits (LSI), the circuit line width required for semiconductor devices has become increasingly narrower. Improvement of yield is indispensable for the manufacture of LSIs which require enormous manufacturing costs. However, as typified by 1-gigabit class DRAM (dynamic random access memory), the patterns constituting LSIs are on the order of submicrons to nanometers. In recent years, along with the miniaturization of LSI pattern dimensions formed on semiconductor wafers, the dimensions that must be detected as pattern defects have also become extremely small. Therefore, there is a demand for higher accuracy of pattern inspection apparatuses that inspect defects of ultrafine patterns transferred onto semiconductor wafers.

[0003] In inspection equipment, for example, a multi-beam system using electron beams is used to irradiate the substrate under inspection, and secondary electrons corresponding to each beam emitted from the substrate are individually detected to capture a pattern image. Inspection is then performed by comparing the captured measurement image with design data or measurement images of the same pattern on the substrate. For example, there is "die-to-die inspection," which compares measurement image data of the same pattern at different locations on the same substrate, and "die-to-database inspection," which generates design image data (reference image) based on the design data of the pattern, and compares it with measurement images that capture the pattern. The captured images are sent to a comparison circuit as measurement data. In the comparison circuit, after aligning the images, the measurement data and reference data are compared according to an appropriate algorithm, and if they do not match, it is determined that there is a pattern defect.

[0004] Furthermore, in devices that acquire images using electron beams, such as inspection equipment, the trajectory of the primary electron beam irradiating the sample is adjusted as a preliminary step before capturing an image of the sample. Conventionally, the primary electron beam was adjusted so that it passed through the center of the lens of the primary electron optical system, but this alone made it difficult to optimize the beam size on the sample surface. In particular, when using multi-electron beams, optimizing the beam size distribution was difficult.

[0005] Here, a technique is disclosed in which the source conversion unit minimizes and compensates for off-axis aberrations of the objective lens and condenser lens, thereby minimizing the size of multiple probe spots (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Special Publication No. 2018-520495 [Overview of the project] [Problems that the invention aims to solve]

[0007] One aspect of the present invention provides an electron beam adjustment method and apparatus that can bring the beam size irradiated onto a sample surface closer to an optimal state. [Means for solving the problem]

[0008] One embodiment of the present invention is an electron beam adjustment method, The process involves scanning the sample with a primary electron beam, A step of detecting a secondary electron beam emitted from the sample due to scanning, The process involves using a secondary electron image obtained from the detection results of a secondary electron beam to acquire parameters from the secondary electron image, A step of adjusting the incidence angle of the primary electron beam onto the sample using parameters, It is characterized by having the following features.

[0009] Furthermore, the process of setting multiple small regions in the secondary electronic image is further included. It is preferable to obtain the vector from the center of the secondary electron image to the subregion where an image was obtained with a beam having a smaller beam area among several subregions as a parameter.

[0010] Furthermore, it is preferable to adjust the angle of incidence so that the parameter or the value obtained using the parameter is below the allowable value.

[0011] Furthermore, a multi-primary electron beam is used as the primary electron beam. The process involves setting multiple sub-regions in each of the multiple secondary electron images using multiple secondary electron images corresponding to multiple primary electron beams in a multi-primary electron beam, and For each secondary electron image, the process involves calculating a vector from the center of the secondary electron image to a subregion among several subregions where an image was obtained with a beam having a smaller beam area, and The process involves calculating the sum of the vectors calculated for each secondary electron image, Furthermore, It is preferable to adjust the angle of incidence so that the sum of the vectors is less than or equal to the allowable value.

[0012] A multi-electron beam position evaluation method according to one aspect of the present invention is: The process involves scanning the sample with a multi-primary electron beam, A step of detecting a multi-secondary electron beam emitted from the sample due to scanning, The process involves setting multiple sub-regions in each of the multiple secondary electron images using multiple secondary electron images obtained from the detection results of multiple secondary electron beams among the multiple secondary electron beams, and For each secondary electron image, the process involves determining the subregion from among several subregions where an image was obtained with a beam having a smaller beam area, and For each secondary electron image, the process involves calculating a vector from the center of the secondary electron image to a determined small region, The process involves calculating and outputting the sum of the vectors obtained from each secondary electron image. It is characterized by having the following features.

[0013] An electron beam image acquisition apparatus according to one aspect of the present invention is: A stage on which the sample is placed, A first deflector scans the sample with the primary electron beam by deflecting the beam, A detector that detects a secondary electron beam emitted from the sample due to scanning, A parameter acquisition unit that uses a secondary electron image obtained from the detection results of a secondary electron beam to acquire parameters from the secondary electron image, A second deflector adjusts the incident angle of the primary electron beam onto the sample by using parameters to deflect the beam, It is characterized by having the following features. [Effects of the Invention]

[0014] According to one aspect of the present invention, the beam size irradiated onto the sample surface can be brought closer to an optimal state. [Brief explanation of the drawing]

[0015] [Figure 1] It is a configuration diagram showing the configuration of the pattern inspection apparatus according to the first embodiment. [Figure 2] It is a conceptual diagram showing the configuration of the shaped aperture array substrate according to the first embodiment. [Figure 3] It is a diagram for explaining image acquisition processing according to the first embodiment. [Figure 4] It is a flowchart showing an example of main steps of the electron beam adjustment method according to the first embodiment. [Figure 5] It is a diagram for explaining the electron beam adjustment method according to the first embodiment. [Figure 6] It is a block diagram showing an example of the internal configuration of the beam adjustment circuit according to the first embodiment. [Figure 7] It is a diagram showing an example of secondary electron images obtained by primary electron beams at the center and four corners according to the first embodiment. [Figure 8] It is a diagram showing an example of a processing region on a secondary electron image and a spatial frequency image according to the first embodiment. [Figure 9] It is a diagram for explaining vector calculation according to the first embodiment. [Figure 10] It is a diagram showing an example of a secondary electron image obtained by multiple electron beams before incident angle adjustment according to the first embodiment. [Figure 11] It is a diagram showing an example of a secondary electron image obtained by multiple electron beams after incident angle adjustment according to the first embodiment. [Figure 12] It is a configuration diagram showing an example of the internal configuration of a comparison circuit according to the first embodiment. [Figure 13] It is a diagram for explaining an electron beam adjustment method in a modification of the first embodiment. Mode for Carrying Out the Invention

[0016] In the following embodiments, a multi-electron beam inspection system will be described as an example of an electron beam image acquisition system. However, the image acquisition system is not limited to inspection systems; any system that acquires images using an electron beam is acceptable. For example, a scanning electron microscope (SEM) may also be used.

[0017] Embodiment 1. Figure 1 is a configuration diagram showing the configuration of a pattern inspection apparatus in Embodiment 1. In Figure 1, the inspection apparatus 100 for inspecting patterns formed on a substrate is an example of a multi-electron beam inspection apparatus. The inspection apparatus 100 includes an image acquisition mechanism 150 and a control system circuit 160. The image acquisition mechanism 150 includes an electron beam column 102 (electron tube), an inspection chamber 103, a detection circuit 106, a chip pattern memory 123, a stage drive mechanism 142, and a laser length measurement system 122. Inside the electron beam column 102 are an electron gun 201, a molded aperture array substrate 203, an electromagnetic lens 205, a deflector 212, a limiting aperture substrate 213, an electromagnetic lens 206, a deflector 211, a deflector 208, an electromagnetic lens 207, a beam separator 214 (an example of a separator), a deflector 218, a deflector 226, an electromagnetic lens 224, and a multi-detector 222.

[0018] The deflector 208, electromagnetic lens 207, and beam separator 214 are positioned on the common trajectory of the multi-primary electron beam 20 and the multi-secondary electron beam 300. The deflector 218, deflector 226, electromagnetic lens 224, and multi-detector 222 are positioned on the trajectory of the multi-secondary electron beam 300, which has been separated from the trajectory of the multi-primary electron beam 20.

[0019] The primary electron optical system 151 is composed of an electron gun 201, a molded aperture array substrate 203, an electromagnetic lens 205, a deflector 212, a limiting aperture substrate 213, an electromagnetic lens 206, a deflector 211, a deflector 208, and an electromagnetic lens 207 (objective lens). The secondary electron optical system 152 is composed of an electromagnetic lens 207 (objective lens), a deflector 208, a beam separator 214, a deflector 218, a deflector 226, and an electromagnetic lens 224.

[0020] The primary electron optical system 151 irradiates the substrate 101 with a multi-primary electron beam 20. The secondary electron optical system 152 projects the multi-secondary electron beam 300, separated from the trajectory of the multi-primary electron beam 20, onto the multi-detector 222.

[0021] The electromagnetic lens group, consisting of electromagnetic lenses 205, 206, 207, and 224, is not limited to a single-stage electromagnetic lens; it may consist of multiple stages of electromagnetic lenses. Furthermore, electrostatic lenses may be used in place of each of the electromagnetic lenses in this group. Alternatively, it may be composed of a combination of electromagnetic and electrostatic lenses. In short, the electromagnetic lens group can consist of any type of electronic lens.

[0022] Furthermore, the deflectors 212, 211, 208, and 226 are not limited to single-stage deflectors, but may be composed of multiple stages. Also, the deflectors 212, 211, 208, and 226 may be, for example, electrostatic deflectors. However, they are not limited to this. Electromagnetic deflectors may be used instead of electrostatic deflectors. Alternatively, they may be composed of a combination of electrostatic and electromagnetic deflectors.

[0023] In the example shown in Figure 1, the case in which electromagnetic deflectors such as alignment coils are used as deflectors 212 and 211 is explained. Furthermore, the case in which electrostatic deflectors such as electrostatic deflectors are used as deflectors 208 and 226 is explained.

[0024] Furthermore, the deflector 211 is preferably positioned upstream of the beam separator 214 on the primary electron beam trajectory. Similarly, the deflector 212 is preferably positioned upstream of the deflector 211 on the primary electron beam trajectory. The deflector 212 is positioned offset in the direction of the electron beam trajectory center axis from the intermediate image plane of each beam of the multi-primary electron beam.

[0025] A stage 105, which is movable in at least the X and Y directions, is placed inside the inspection chamber 103. Multiple support rods 210 are individually positioned on the stage 105, and the substrate 101 (sample) to be inspected is supported by the multiple support rods 210. In other words, the substrate 101 is placed on the stage 105 with, for example, the pattern-forming surface facing upwards. In the example in Figure 1, for example, it is supported at three points by three support rods 210. In addition, an evaluation substrate 400 for electron beam adjustment is placed on the stage instead of substrate 101.

[0026] 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, multiple chip patterns (wafer dies) are formed on the semiconductor substrate. When the substrate 101 is an exposure mask substrate, chip patterns are formed on the exposure mask substrate. The chip pattern is composed of multiple graphic patterns. By exposing and transferring the chip pattern formed on the exposure mask substrate onto the semiconductor substrate multiple times, multiple chip patterns (wafer dies) are formed on the semiconductor substrate. The following explanation will mainly focus on the case where the substrate 101 is an exposure mask substrate.

[0027] Furthermore, a mirror 216 is positioned on the stage 105 to reflect the laser beam used for laser length measurement, which is emitted from the laser length measurement system 122 located outside the inspection room 103.

[0028] Furthermore, the multi-detector 222 is connected to the detection circuit 106 outside the electron beam column 102. The detection circuit 106 is connected to the chip pattern memory 123. Multiple detection elements are arranged in the multi-detector 222 in an arrangement similar to that of the multi-secondary electron beam 300.

[0029] In the control system circuit 160, the control computer 110, which controls the entire inspection device 100, is connected via the bus 120 to the position circuit 107, comparison circuit 108, reference image creation circuit 112, stage control circuit 114, lens control circuit 124, blanking control circuit 126, deflection control circuit 128, separator control circuit 132, beam adjustment circuit 134, storage device 109 such as a magnetic disk drive, monitor 117, memory 118, and printer 119.

[0030] Furthermore, the deflection control circuit 128 is connected to DAC (digital-to-analog converter) amplifiers 146 and 149. DAC amplifier 146 is connected to deflector 208. DAC amplifier 149 is connected to deflector 226. Furthermore, the deflection control circuit 128 is connected to the voltage-controlled power supply 148. The voltage-controlled power supply 148 is connected to the deflector 218 (bender).

[0031] Furthermore, the chip pattern memory 123 is connected to the comparison circuit 108. The stage 105 is driven by the drive mechanism 142 under the control of the stage control circuit 114. The drive mechanism 142 is configured with a drive system such as a 3-axis (XY-θ) motor that drives in the X, Y, and θ directions in the stage coordinate system, allowing the stage 105 to move in the XYθ direction. These X motor, Y motor, and θ motor, which are not shown, can be, for example, stepper motors. The stage 105 is movable in the horizontal and rotational directions by the motors of each XYθ axis. The movement position of the stage 105 is measured by the laser length measuring system 122 and supplied to the position circuit 107. The laser length measuring system 122 measures the position of the stage 105 by receiving reflected light from the mirror 216 using the principle of laser interferometry. The stage coordinate system is set, for example, with respect to a plane perpendicular to the optical axis of the multi-primary electron beam 20, where the X, Y, and θ directions of the primary coordinate system are set.

[0032] The deflectors 212, 211, electromagnetic lenses 205, 206, 207, 224, and beam separator 214 are controlled by the lens control circuit 124. The 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 226 is composed of four or more electrodes, and each electrode is controlled by the deflection control circuit 128 via the DAC amplifier 149.

[0033] The deflector 218 (bender) is configured, for example, as a cylindrical shape bent in an arc shape with multiple electrodes of four or more poles, and each electrode is controlled by a deflection control circuit 128 via a voltage control power supply 148. Alternatively, the deflector 218 may be configured as a flat plate with multiple electrodes of four or more poles, and each electrode may be controlled by a deflection control circuit 128 via a voltage control power supply 148.

[0034] The beam separator 214 has its electric and magnetic fields controlled by the separator control circuit 132. For example, an E×B separator is preferable as the beam separator 214. Alternatively, an electromagnetic prism is also preferable as the beam separator 214. Figure 1 shows an example where an E×B separator is used as the beam separator 214.

[0035] In addition, it is preferable to configure the system to adjust the energy of the multi-primary electron beam 20 irradiated onto the substrate 101 by applying a desired retarding potential to the substrate 101 from a retarding control circuit (not shown). For example, a negative potential is applied to the substrate 101.

[0036] A high-voltage power supply circuit (not shown) is connected to the electron gun 201. An acceleration voltage from the high-voltage power supply circuit is applied between a filament (not shown) and an extraction electrode within the electron gun 201. Simultaneously, a voltage is applied to a predetermined extraction electrode (Wähnelt), and the cathode is heated to a predetermined temperature. This accelerates the group of electrons emitted from the cathode, which are then emitted as an electron beam 200.

[0037] The memory device 109 stores the design data (design pattern data) that forms the basis of the patterns formed on the substrate 101.

[0038] Here, Figure 1 shows the configuration necessary to explain Embodiment 1. The inspection device 100 may also have other configurations that are normally necessary.

[0039] Figure 2 is a conceptual diagram showing the configuration of a molded aperture array substrate in Embodiment 1. In Figure 2, the molded aperture array substrate 203 has two-dimensional holes (openings) 22 arranged in m1 horizontal (x-direction) rows × n1 vertical (y-direction) rows (m1, n1 are integers of 2 or more) at a predetermined arrangement pitch in the x and y directions. The example in Figure 2 shows a case where 5 × 5 holes (openings) 22 are formed. Each hole 22 is formed as a circle with the same outer diameter. Alternatively, they may be rectangles of the same dimensions and shape. A portion of the electron beam 200 passes through each of these multiple holes 22 to form a multi-primary electron beam 20. The molded aperture array substrate 203 is an example of a multi-primary electron beam formation mechanism for forming a multi-primary electron beam.

[0040] The image acquisition mechanism 150 uses a multi-beam electron beam to acquire an image of the graphic pattern from the substrate 101 on which the graphic pattern is formed. The operation of the image acquisition mechanism 150 in the inspection apparatus 100 will be described below.

[0041] An electron gun 201 (an example of an emission source) emits an electron beam 200 in a divergent direction. The electron beam 200 emitted from the electron gun 201 illuminates the entire molded aperture array substrate 203. As shown in Figure 2, a plurality of holes 22 (openings) are formed in the molded aperture array substrate 203, and the electron beam 200 illuminates the region containing all of the plurality of holes 22. A multi-primary electron beam 20 is formed as each portion of the electron beam 200 irradiated at the location of the plurality of holes 22 passes through each of the plurality of holes 22 in the molded aperture array substrate 203.

[0042] The formed multi-primary electron beam 20 is refracted by electromagnetic lenses 205 and 206, respectively, and proceeds to the beam separator 214, which is located at the intermediate image plane (image plane conjugate position) of each beam of the multi-primary electron beam 20, while repeatedly creating intermediate images and crossovers. Furthermore, scattered beams can be shielded by placing a restricting aperture substrate 213 with limited passage holes near the crossover position of the multi-primary electron beam 20.

[0043] When the multi-primary electron beam 20, having passed through the beam separator 214, enters the electromagnetic lens 207, the electromagnetic lens 207 images the multi-primary electron beam 20 onto the substrate 101. In other words, the electromagnetic lens 207 uses the multi-primary electron beam 20 to image the multi-primary electron beam 20 onto the substrate 101. The multi-primary electron beam 20, which has been focused (aligned) onto the surface of the substrate 101 (sample) by the electromagnetic lens 207, is deflected collectively by the deflector 208 and irradiates each beam to its respective irradiation position on the substrate 101. In this way, the primary electron optical system 151 irradiates the surface of the substrate 101 with the multi-primary electron beam.

[0044] When the multi-primary electron beam 20 is irradiated onto a desired location on the substrate 101, a bundle of secondary electrons (multi-secondary electron beam 300) containing reflected electrons, corresponding to each beam of the multi-primary electron beam 20, is emitted from the substrate 101 as a result of the irradiation by the multi-primary electron beam 20.

[0045] The multi-secondary electron beam 300 emitted from the substrate 101 passes through the electromagnetic lens 207 and the deflector 208 and proceeds to the beam separator 214. The beam separator 214 (separator) separates the multi-secondary electron beam 300 from the trajectory of the multi-primary electron beam 20.

[0046] Here, an E×B separator, which is an example of a beam separator 214, has multiple magnetic poles (two or more) using coils and multiple electrodes (two or more). These multiple magnetic poles generate a directional magnetic field. Similarly, the multiple electrodes generate a directional electric field. Specifically, the E×B separator generates electric and magnetic fields in orthogonal directions on a plane perpendicular to the direction in which the central beam of the multi-primary electron beam 20 travels (orbital axis). The electric field exerts a force in the same direction regardless of the direction of electron propagation. In contrast, the 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 of electron entry. For the multi-primary electron beam 20 entering the E×B separator 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 downwards. In contrast, the multi-secondary electron beam 300, which enters the E×B separator from below, is subjected to both electric and magnetic field forces acting in the same direction. This causes the multi-secondary electron beam 300 to be statically bent diagonally upward, separating it from the trajectory of the multi-primary electron beam 20.

[0047] The multi-secondary electron beam 300, which has been deflected diagonally upward and separated from the multi-primary electron beam 20, is projected onto the multi-detector 222 by the secondary electron optical system 152. Specifically, the multi-secondary electron beam 300 separated from the multi-primary electron beam 20 proceeds to the deflector 218. The deflector 218 is positioned on the trajectory of the multi-secondary electron beam 300, which has been separated from the trajectory of the multi-primary electron beam 20, and is conjugate to the detection surface of the multi-detector 222. Specifically, the deflector 218 is positioned such that an intermediate position within the deflector 218 (for example, an intermediate position) is conjugate to the detection surface of the multi-detector 222. The multi-secondary electron beam 300 is then further deflected by static deflection by the deflector 218. The multi-secondary electron beam 300, statically deflected by the deflector 218, is projected onto the multi-detector 222 at a position away from the trajectory of the multi-primary electron beam 20, while being refracted in the focusing direction by the electromagnetic lens 224. The multi-detector 222 (multi-secondary electron beam detector) individually detects the refracted and projected multi-secondary electron beam 300.

[0048] Then, each beam of the multi-secondary electron beam 300 collides with the detection element corresponding to each secondary electron beam of the multi-detector 222 on the detection surface of the multi-detector 222, generating electrons and creating secondary electron image data for each pixel. The intensity signal detected by the multi-detector 222 is output to the detection circuit 106. As described above, the multi-detector 222 is composed of multiple detection elements. The signal from each detection element is output to the detection circuit 106 for each detection element.

[0049] Figure 3 is a diagram illustrating the image acquisition process in Embodiment 1. As shown in Figure 3, the inspection area 330 of the substrate 101 is divided into a plurality of stripe areas 32 with a predetermined width in the y direction, for example. The scanning operation by the image acquisition mechanism 150 is performed for each stripe area 32, for example. For example, the scanning operation of the stripe areas 32 is advanced in the x direction relative to the stage 105 while moving the stage 105 in the -x direction. Each stripe area 32 is divided into a plurality of rectangular areas 33 in the longitudinal direction. The movement of the beam to the target rectangular area 33 is performed by simultaneous deflection of the entire multi-primary electron beam 20 by the deflector 208.

[0050] The example in Figure 3 shows, for example, a 5x5 row multi-primary electron beam 20. The irradiation area 34 that can be irradiated with one irradiation of the multi-primary electron beam 20 is defined as (x-direction size obtained by multiplying the design beam pitch in the x-direction of the multi-primary electron beam 20 on the surface of the substrate 10 by the number of beams in the x-direction) × (y-direction size obtained by multiplying the design beam pitch in the y-direction of the multi-primary electron beam 20 on the surface of the substrate 10 by the number of beams in the y-direction). The irradiation area 34 becomes the field of view of the multi-primary electron beam 20. Each primary electron beam 10 constituting the multi-primary electron beam 20 is irradiated into a sub-irradiation area 29 enclosed by the design beam pitch in the x-direction and the design beam pitch in the y-direction where its beam is located, and scans (scans) within the sub-irradiation area 29. Each primary electron beam 10 will be responsible for one of the sub-irradiation areas 29 which is different from each other. Each primary electron beam 10 then irradiates the same location within its assigned sub-irradiation area 29. The deflector 208 deflects the multi-primary electron beam 20 collectively, scanning the surface of the patterned substrate 101 with the multi-primary electron beam 20. In other words, the movement of the primary electron beam 10 within the sub-irradiation area 29 is performed by the collective deflection of the entire multi-primary electron beam 20 by the deflector 208. This operation is repeated, sequentially irradiating one sub-irradiation area 29 with one primary electron beam 10.

[0051] The width of each stripe region 32 is preferably set to be the same as the y-direction size of the irradiation region 34, or narrower by the scan margin. In the example in Figure 3, the case where the irradiation region 34 is the same size as the rectangular region 33 is shown. However, this is not the only case. The irradiation region 34 may be smaller than the rectangular region 33, or it may be larger. Each primary electron beam 10 constituting the multi-primary electron beam 20 is irradiated into the sub-irradiation region 29 where its beam is located, and scans (scans) within the sub-irradiation region 29. Once the scan of one sub-irradiation region 29 is completed, the entire multi-primary electron beam 20 is deflected by the deflector 208 and moves to an adjacent rectangular region 33 within the same stripe region 32. This operation is repeated, sequentially irradiating within the stripe region 32. Once scanning one stripe region 32 is complete, the irradiation region 34 moves to the next stripe region 32 by moving the stage 105 and / or by the deflector 208, which simultaneously deflects the entire multi-primary electron beam 20. In this way, each primary electron beam 10 irradiates a sub-irradiated region 29, and a secondary electron image is acquired. By combining these secondary electron images from each sub-irradiated region 29, a secondary electron image of the rectangular region 33, a secondary electron image of the stripe region 32, or a secondary electron image of the chip 332 is constructed. Furthermore, when actually comparing images, the sub-irradiated region 29 within each rectangular region 33 is further divided into multiple frame regions 30, and the frame images 31, which are the measurement images for each frame region 30, are compared. The example in Figure 3 shows a case where the sub-irradiated region 29 scanned by one primary electron beam 10 is divided into four frame regions 30, for example, by dividing it into two in each of the x and y directions.

[0052] In the example in Figure 3, the first stripe region 32 moves in the x-direction (forward (FWD) direction), the second stripe region 32 moves in the -x direction (backward (BWD) direction), and the third stripe region 32 moves in the x-direction (forward (FWD) direction), showing a case where the scanning direction alternates. However, this is not the only option. All stripe regions 32 may be scanned in the same direction. Also, the scanning direction of the sub-irradiation region 29 is reversed between FWD and BWD. In the example in Figure 3, the line scan repeat direction is shown as an FWD scan, moving from left to right within the sub-irradiation region 29. In BWD, the line scan repeat direction is from right to left within the sub-irradiation region 29. Each line scan is the same in that it moves, for example, from bottom to top (y direction).

[0053] In this case, when the stage 105 moves continuously and irradiates the substrate 101 with the multi-primary electron beam 20, the deflector 208 performs a tracking operation by simultaneous deflection so that the irradiation position of the multi-primary electron beam 20 follows the movement of the stage 105.

[0054] As described above, the image acquisition mechanism 150 proceeds with the scanning operation for each stripe region 32. As described above, the multi-primary electron beam 20 is irradiated, and the multi-secondary electron beam 300 emitted from the substrate 101 due to the irradiation of the multi-primary electron beam 20 forms an intermediate image plane in the deflector 218, is statically deflected by the deflector 218, and is then detected by the multi-detector 222. The detected multi-secondary electron beam 300 may contain backscattered electrons. Alternatively, the backscattered electrons may diverge while moving through the secondary electron optical system and may not reach the multi-detector 222. Then, a secondary electron image is acquired based on the signal of the detected multi-secondary electron beam 300.

[0055] Furthermore, when scanning is performed while the stage 105 is moving continuously, trunking control is performed by the deflector 208 so that the irradiation position of the multi-primary electron beam 20 on the substrate 101 follows the movement of the stage 105.

[0056] Furthermore, scanning the substrate 101 with the multi-primary electron beam 20 causes the emission position of the emitted multi-secondary electron beam 300 to change moment by moment. Similarly, the emission position of the emitted multi-secondary electron beam 300 also changes moment by moment due to trunking control. If left as is, the position of the multi-secondary electron beam 300 on the detection surface of the multi-detector 222 will shift, preventing each secondary electron beam from entering its corresponding detection element. Therefore, the multi-secondary electron beam 300 is dynamically deflected collectively by the deflector 226 to correct the distance shifted by scanning with the multi-primary electron beam 20 and trunking control, thereby fixing the position of the multi-secondary electron beam 300 on the detection surface of the multi-detector 222. When scanning is performed in step-and-repeat operation, trunking control is unnecessary, in which case the multi-secondary electron beam 300 can be dynamically deflected collectively by the deflector 226 to correct the distance shifted by scanning with the multi-primary electron beam 20.

[0057] In order to acquire the image described above, the primary electron beam trajectory must be adjusted before acquiring an image of the substrate 101 to be inspected. Conventionally, the beam axis was adjusted so that the primary electron beam passed through the lens center of the primary electron optical system, but this alone made it difficult to optimize the beam size on the sample surface. In particular, when using a multi-primary electron beam 20, it was difficult to optimize the beam size distribution. Therefore, in Embodiment 1, a deflector 212 is used to deflect the multi-primary electron beam 20, and the evaluation substrate 400 is scanned with the multi-primary electron beam 20. Then, using the obtained secondary electron image, the incidence angle of the primary electron beam onto the evaluation substrate (sample) is adjusted so that the beam size distribution approaches an optimal state. A detailed explanation follows below.

[0058] Figure 4 is a flowchart showing an example of the main steps of the electron beam adjustment method in Embodiment 1. In Figure 4, the electron beam adjustment method in Embodiment 1 includes the following steps: evaluation substrate loading step (S102), scanning step (S104), image acquisition step (S106), processing area setting step (S108), spatial frequency image generation step (S112), signal area calculation step (S114), optimal processing area determination step (S116), vector calculation step (S118), vector sum calculation step (S120), determination step (S130), and incident angle adjustment step (S140).

[0059] Furthermore, the electron beam position evaluation method in Embodiment 1 includes the following steps from the series of steps described above: evaluation substrate loading step (S102), scanning step (S104), image acquisition step (S106), processing area setting step (S108), spatial frequency image generation step (S112), signal area calculation step (S114), optimal processing area determination step (S116), vector calculation step (S118), and vector sum calculation step (S120).

[0060] As part of the evaluation board loading process (S102), the evaluation board 400 is loaded into the inspection room 103 and placed on the stage 105.

[0061] For example, a large number of gold particles are arranged on the evaluation substrate 400. However, this is not limited to this. Any arrangement that allows for the measurement of blurring, etc., from the resulting image is acceptable. For example, it is also preferable to have multiple rectangular or circular patterns formed. The location and size of the area where the numerous gold particles or multiple patterns are arranged can be arbitrary, but here, it is preferable that the numerous gold particles or patterns are formed in an area larger than the irradiation area that the multi-primary electron beam 20 can irradiate. Note that the substrate 101 to be inspected may be placed instead of the evaluation substrate 400.

[0062] In the scanning process (S104), the deflector 212 (first deflector) scans the evaluation substrate 400 (sample) with a multi-primary electron beam 20 (an example of a primary electron beam).

[0063] Figure 5 is a diagram illustrating the electron beam adjustment method in Embodiment 1. As shown in Figure 5, the multi-primary electron beam 20 that has passed through the apertures of the deflector 212 and limiting aperture 213 is refracted by the electromagnetic lenses 206 and 207 and irradiates the evaluation substrate 400. At this time, the deflector 212 deflects the multi-primary electron beam 20. This allows the evaluation substrate 400 to be scanned with the multi-primary electron beam 20. During such scanning, beam deflection by the deflector 208 is not performed.

[0064] In the image acquisition process (S106), the multi-detector 222 detects the multi-secondary electron beam 300 (an example of a secondary electron beam) emitted from the evaluation substrate 400 due to scanning in the scanning process (S104). Specifically, the multi-secondary electron beam 300 emitted from the evaluation substrate 400 passes through the electromagnetic lens 207 and the deflector 208, then its trajectory is bent by the beam separator 214, and the positional shift caused by beam deflection during the scanning operation is swung back by the deflector 226 before it enters the multi-detector 222. As a result, the multi-detector 222 individually detects the multi-secondary electron beam 300 corresponding to the multi-primary electron beam 20. From this detection data, a secondary electron image of each secondary electron beam is individually generated.

[0065] Figure 6 is a block diagram showing an example of the internal configuration of a beam adjustment circuit in Embodiment 1. In Figure 6, the beam adjustment circuit 134 includes a processing area setting unit 60, a spatial frequency image generation unit 62, a signal area calculation unit 64, a processing area determination unit 68, a vector calculation unit 70, a vector sum calculation unit 72, and a determination unit 74. The "~ unit" in "~ unit" includes a processing circuit, and that processing circuit includes electrical circuits, computers, processors, circuit boards, quantum circuits, or semiconductor devices. Furthermore, each "~ unit" may use a common processing circuit (the same processing circuit), or it may use different processing circuits (separate processing circuits). The necessary input data or calculated results for the processing area setting unit 60, spatial frequency image generation unit 62, signal area calculation unit 64, processing area determination unit 68, vector calculation unit 70, vector sum calculation unit 72, and determination unit 74 are stored each time in a memory (not shown) or memory 118 within the beam adjustment circuit 134.

[0066] As a processing area setting step (S108), the processing area setting unit 60 sets multiple processing areas (small areas) in the secondary electron image. Here, using multiple secondary electron images obtained from the detection results of multiple secondary electron beams from the multi-secondary electron beam 300, the processing area setting unit 60 sets multiple processing areas (small areas) in each of the multiple secondary electron images. In other words, using multiple secondary electron images corresponding to multiple primary electron beams from the multi-primary electron beam 20, the processing area setting unit 60 sets multiple processing areas (small areas) in each of the multiple secondary electron images.

[0067] Figure 7 shows an example of a secondary electron image obtained with the central and four corner primary electron beams in Embodiment 1. In the example in Figure 7, the secondary electron images obtained when scanning the evaluation substrate 400 using 5 × 5 multi-primary electron beams 20 are shown, specifically those obtained by scanning with the central primary electron beam and the four corner primary electron beams. Each secondary electron image captures the aperture image of the limiting aperture substrate 213 obtained by scanning with the corresponding primary electron beam, and also captures gold particle images of the evaluation substrate 400 within the aperture image. The example in Figure 7 shows the secondary electron image obtained by scanning the primary electron beam at coordinate (2,2) in the center. The secondary electron image obtained by scanning the primary electron beam at coordinate (0,0) is shown in the lower left. The secondary electron image obtained by scanning the primary electron beam at coordinate (4,0) is shown in the lower right. The secondary electron image obtained by scanning the primary electron beam at coordinate (0,4) is shown in the upper left. The secondary electron image obtained by scanning the primary electron beam at coordinate (4,4) is shown in the upper right.

[0068] Figure 8 shows an example of a processing region and spatial frequency image on a secondary electron image in Embodiment 1. In the example in Figure 8, the secondary electron images obtained from scanning with the central primary electron beam and the four corner primary electron beams are shown, out of 5 × 5 secondary electron images obtained when scanning the evaluation substrate 400 using 5 × 5 multi-primary electron beams 20. In the example in Figure 8, a case is shown in which, for example, a 3 × 3 processing region 12 is set within the aperture image in each secondary electron image in Figure 7. In the example in Figure 8, each processing region 12 is shown as a rectangular region, but it is not limited to this. For example, it may be set as a circle or other shape. Also, the number of regions is not limited to 3 × 3. There may be more. For example, setting a 5 × 5 processing region is also preferable.

[0069] In the spatial frequency image generation process (S112), the spatial frequency image generation unit 62 performs a Fourier transform (2D FFT) on the image within each processing region 12 for each secondary electron image to generate a spatial frequency image. The example in Figure 8 shows an example of a spatial frequency image representing the frequency spectrum (signal) within each processing region 12.

[0070] As part of the signal area calculation process (S114), the signal area calculation unit 64 calculates the area of ​​the frequency spectrum (signal) of each processing region 12. The larger the area of ​​the signal, the more it indicates that the image was obtained with the smallest beam area in the spatial region of the processing region 12. Furthermore, the method for determining the beam area is not limited to spatial frequency. In addition to generating spatial frequency images for each processing region 12, the beam area can also be estimated by, for example, taking edge profiles in each representative direction for each processing region 12 and approximating them with an error function. For example, for a sample with edges in all directions, such as gold particles, the beam diameter for each direction can be calculated by extracting edge profiles from various directions (e.g., 8 directions) and approximating them with an error function, for example, using a general DR method.

[0071] As an optimal processing area determination step (S116), the processing area determination unit 68 determines, for each secondary electron image, the processing area 12 from among multiple processing areas 12 in which an image was obtained with the beam having the smallest beam area as the optimal processing area. In the example in Figure 8, for example, in the secondary electron image at coordinate (0,0), the lower left processing area 12 is determined as the optimal processing area. For example, in the secondary electron image at coordinate (4,0), the lower right processing area 12 is determined as the optimal processing area. For example, in the secondary electron image at coordinate (0,4), the left center processing area 12 is determined as the optimal processing area. For example, in the secondary electron image at coordinate (4,4), the upper right processing area 12 is determined as the optimal processing area. For example, in the secondary electron image at coordinate (2,2), the center processing area 12 is determined as the optimal processing area.

[0072] As part of the vector calculation process (S118), the vector calculation unit 70 (parameter acquisition unit) uses the secondary electron image obtained from the detection results of the secondary electron beam to acquire parameters from the secondary electron image. It then calculates a vector as the parameter.

[0073] Figure 9 is a diagram illustrating the vector calculation in Embodiment 1. In Figure 9, the processing region image is shown faintly to make it easier to understand the positional relationship of the vectors. Specifically, the vector calculation unit 70 obtains as a parameter the vector from the center of the secondary electron image to the processing region among the multiple processing regions 12 in which an image was obtained with a beam having a smaller beam area. Here, for each secondary electron image, the vector calculation unit 70 calculates the vector from the center of the secondary electron image to the processing region among the multiple processing regions 12 in which an image was obtained with a beam having a smaller beam area (the determined optimal processing region).

[0074] In the example in Figure 8, for example, in the secondary electron image at coordinate (0,0), the vector from the center of the secondary electron image to the center of the processing region 12 in the lower left is calculated. For example, in the secondary electron image at coordinate (4,0), the vector from the center of the secondary electron image to the center of the processing region 12 in the lower right is calculated. For example, in the secondary electron image at coordinate (0,4), the vector from the center of the secondary electron image to the center of the processing region 12 in the left center is calculated. For example, in the secondary electron image at coordinate (4,4), the vector from the center of the secondary electron image to the center of the processing region 12 in the upper right is calculated. For example, in the secondary electron image at coordinate (2,2), the central processing region 12 is the optimal processing region, so the center of the secondary electron image and the center of the central processing region 12 coincide. Therefore, the vector is zero.

[0075] As part of the vector sum calculation process (S120), the vector sum calculation unit 72 calculates the sum of the vectors calculated for each secondary electron image. In the example in Figure 8, the sum of the vector calculated for the secondary electron image at coordinate (0,0), the vector calculated for the secondary electron image at coordinate (4,0), the vector calculated for the secondary electron image at coordinate (0,4), the vector calculated for the secondary electron image at coordinate (4,4), and the vector calculated for the secondary electron image at coordinate (2,2) is calculated. The sum of the calculated vectors is output to and stored in the storage device 109.

[0076] By obtaining the sum of these vectors, if the sum of the vectors is greater than the allowable value Th, it can be determined that the beam size distribution of the multi-primary electron beam is not the desired distribution (the vectors obtained in each sub-region are symmetrical with respect to the central beam) (ideally, the sum of the vectors should be zero). In other words, it can be determined that the incident position of the multi-primary electron beam is misaligned and the incident angle is incorrect. In this way, the position of the multi-primary electron beam can be evaluated by obtaining the sum of the vectors. In Embodiment 1, if the beam position evaluation is not acceptable, further beam adjustment is performed.

[0077] In the determination step (S130), the determination unit 74 determines whether the sum of the calculated vectors is less than or equal to the allowable value Th. If the sum of the vectors is less than or equal to the allowable value Th, the primary electron beam adjustment is completed. If the sum of the vectors is not less than or equal to the allowable value Th, the process proceeds to the incident angle adjustment step (S140).

[0078] In the incident angle adjustment process (S140), the deflector 211 (second deflector) adjusts the incident angle of the multi-primary electron beam 20 (primary electron beam) onto the evaluation substrate 400 (sample) by beam deflection using the obtained parameters. In other words, the deflector 211 adjusts the incident angle of the multi-primary electron beam 20 so that the parameters or the values ​​obtained using the parameters are less than or equal to the allowable value Th. Specifically, the deflector 211 adjusts the incident angle of the multi-primary electron beam 20 by beam deflection as shown in Figure 5 so that the sum of the vectors is less than or equal to the allowable value Th.

[0079] For example, the deflector 211 deflects the multi-primary electron beam 20 by a predetermined deflection amount θ in the opposite direction to the direction of the sum of the vectors. Then, the process returns to the scanning process (S104), and each step from the scanning process (S104) to the incident angle adjustment process (S140) is repeated until the sum of the vectors is less than or equal to the allowable value Th. Although the deflector 211 is a dedicated deflector for adjusting the deflection angle, the deflection angle may also be adjusted using a deflector for aligning the lens axis (not shown).

[0080] Herein, the electron beam adjustment method of Embodiment 1 is not limited to cases where a multi-electron beam is used as the electron beam. It can also be applied when a single beam is used. When a single beam is used, the deflector 211 should adjust the incident angle of the primary electron beam so that the calculated vector itself for the secondary electron image obtained by scanning with the beam is below an acceptable value, rather than the sum of the vectors. In other words, when adjusting a single primary electron beam, the deflector 211 adjusts the incident angle of the primary electron beam 20 so that the parameter is below an acceptable value Th.

[0081] Figure 10 shows an example of a secondary electron image obtained with a multi-electron beam before adjusting the incident angle in Embodiment 1. Figure 11 shows an example of a secondary electron image obtained with a multi-electron beam after adjusting the incident angle in Embodiment 1. As shown in Figure 10, blurring occurs in the secondary electron images obtained with the beams at the four corners, for example, near the center (deflection center). In contrast, by adjusting the incident angle, the blurring in the secondary electron images obtained with the beams at the four corners, for example, near the center (deflection center), can be improved, as shown in Figure 11.

[0082] As a result, the beam size can be brought closer to the optimal state.

[0083] After the electron beam adjustment is completed as described above, the evaluation substrate is removed and the substrate 101 to be inspected is placed on the stage 105. Then, the inspection process is started. The inspection process will be described below.

[0084] As part of the scanning process, the image acquisition mechanism 150 scans the substrate 101 with a multi-primary electron beam 20, detects the multi-secondary electron beam 300 emitted from the substrate 101, and acquires a secondary electron image of the substrate 101. Specifically, it operates as follows: The primary electron optical system 151 irradiates the substrate 101 with the multi-primary electron beam 20. The image acquisition mechanism 150 proceeds with the scanning operation for each stripe region 32.

[0085] Then, the multi-secondary electron beam 300 emitted from the substrate 101 due to irradiation by the multi-primary electron beam 20 is separated from the trajectory of the multi-primary electron beam 20 by static deflection by the beam separator 214, further statically deflected by the deflector 218, and then detected by the multi-detector 222. The detected multi-secondary electron beam 300 may contain backscattered electrons. Alternatively, the backscattered electrons may diverge while moving through the secondary electron optical system and not reach the multi-detector 222. Then, a secondary electron image is acquired based on the signal of the detected multi-secondary electron beam 300. Specifically, the detection data of secondary electrons for each pixel in each sub-irradiation area 29 detected by the multi-detector 222 (measured image data: secondary electron image data: image data under inspection) is output to the detection circuit 106 in the order of measurement. Within the detection circuit 106, the analog detection data is converted to digital data by an A / D converter (not shown) and stored in the chip pattern memory 123. The obtained measurement image data, along with information indicating each position from the position circuit 107, is then transferred to the comparison circuit 108.

[0086] Meanwhile, the reference image creation circuit 112 creates a reference image corresponding to the frame image 31 for each frame region 30, based on the design data that forms the basis of the multiple graphic patterns formed on the substrate 101. Specifically, it operates as follows: First, it reads the design pattern data from the storage device 109 through the control computer 110, and converts each graphic pattern defined in this read-out design pattern data into binary or multi-level image data.

[0087] As mentioned above, the shapes defined in the design pattern data are based on basic shapes such as rectangles and triangles. The data stores shape data that defines the shape, size, position, etc., of each pattern shape, including information such as the coordinates (x, y) at the reference position of the shape, the length of the sides, and a shape code that serves as an identifier to distinguish between different types of shapes such as rectangles and triangles.

[0088] When the design pattern data, which will become such graphic data, is input to the reference image creation circuit 112, it is expanded into data for each graphic, and the graphic code and dimensions indicating the shape of the graphic data are interpreted. Then, it is expanded into binary or multi-level design pattern image data as a pattern to be placed in a grid of predetermined quantization dimensions and output. In other words, the design data is read, the inspection area is virtually divided into a grid of predetermined dimensions, the occupancy rate of the graphic in the design pattern is calculated for each resulting grid, and n-bit occupancy rate data is output. For example, it is preferable to set one grid as one pixel. Then, 1 / 2 8 If we assume a resolution of (=1 / 256), we allocate a small area of ​​1 / 256 the size of the area of ​​the shape placed within the pixel and calculate the occupancy rate within the pixel. This results in 8-bit occupancy rate data. The grid (inspection pixels) used for this should match the pixels of the measurement data.

[0089] Next, the reference image creation circuit 112 applies a filter to the design image data of the design pattern, which is the image data of the shape, using a predetermined filter function. This makes it possible to match the design image data, which is the design-side image data with digital image intensity (grayscale values), to the image generation characteristics obtained by irradiation with the multi-primary electron beam 20. The image data of each pixel of the created reference image is output to the comparison circuit 108.

[0090] As part of the comparison process, the comparison circuit 108 compares the image under inspection with a reference image. Specifically, it operates as follows:

[0091] Figure 12 is a diagram showing an example of the configuration within the comparison circuit in Embodiment 1. In Figure 12, the comparison circuit 108 includes storage devices 50, 52, and 56 such as magnetic disk drives, a frame image creation unit 54, a alignment unit 57, and a comparison unit 58. Each of the "~ unit"s, such as the frame image creation unit 54, the alignment unit 57, and the comparison unit 58, includes a processing circuit, which may include an electrical circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Furthermore, each of the "~ unit" may use a common processing circuit (the same processing circuit), or it may use different processing circuits (separate processing circuits). The necessary input data or calculated results within the frame image creation unit 54, the alignment unit 57, and the comparison unit 58 are stored in a memory (not shown) or memory 118 each time.

[0092] The measurement image data (stripe image) transferred to the comparison circuit 108 is stored in the storage device 50. The reference image data transferred to the comparison circuit 108 is stored in the storage device 52.

[0093] The frame image creation unit 54 then creates frame images 31 for each of the multiple frame regions 30 obtained by further dividing the stripe image data acquired by the scanning operation of each primary electron beam 10. The frame regions 30 are then used as unit regions of the image under inspection. Preferably, each frame region 30 is configured so that its margin regions overlap with each other to prevent any gaps in the image. The created frame images 31 are stored in the storage device 56.

[0094] Next, the alignment unit 57 reads the frame image 31, which is the image to be inspected, and the reference image corresponding to the frame image 31, and aligns the two images in units of sub-pixels smaller than pixels. For example, the least squares method can be used for alignment.

[0095] The comparison unit 58 then compares at least a portion of the acquired secondary electron image with a predetermined image. Here, frame images obtained by further dividing the image of the sub-irradiation region 29 acquired for each beam are used. The comparison unit 58 then compares the frame image 31 and the reference image pixel by pixel. The comparison unit 58 compares the two pixel by pixel according to predetermined judgment conditions and determines the presence or absence of defects, such as shape defects. For example, if the difference in grayscale value for each pixel is greater than the judgment threshold Th, it is determined to be a defect. The comparison result is then output. The comparison result can be output to the storage device 109 or memory 118, or output from the printer 119.

[0096] Figure 13 is a diagram illustrating an electron beam adjustment method in a modified embodiment of Embodiment 1. In Figure 13, a beam selection aperture substrate 240 and an electromagnetic lens 242 are placed between the electromagnetic lens 206 and the deflector 211. The beam selection aperture substrate 240 is positioned at a location different from the crossover of the multi-primary electron beam 20. The beam selection aperture substrate 240 has a large aperture through which the entire multi-primary electron beam 20 can pass, and a small aperture through which one primary electron beam passes and the remaining primary electron beams are shielded. The beam selection aperture substrate 240 is positioned to be movable in a direction perpendicular to the trajectory center axis of the primary electron beam by a drive mechanism (not shown).

[0097] Furthermore, a detector 244 is positioned on the secondary electron orbital. Preferably, the detector 244 is positioned upstream of the deflector 218 in the secondary electron orbital. The detector 244 is positioned to be movable between the secondary electron orbital and outside the secondary electron orbital by a drive mechanism (not shown). The detector 244 is composed of a single detection element, and the size of the detection surface of this detection element is formed to be sufficiently larger than the detection surface of each detection element of the multi-detector 222. Preferably, it is formed to be large enough to detect objects on the detection surface even without deflection to correct positional shifts caused by the scanning operation of the deflector 226.

[0098] Then, in the scanning process (S104), when the scanning operation is performed by deflecting the multi-primary electron beam 20 with the deflector 212, the beam selection aperture substrate 240 allows only the desired primary electron beam 21 from the multi-primary electron beam 20 to pass through. As a result, in the image acquisition process (S106), the detector 244 can detect the secondary electron beam 301 emitted by scanning the evaluation substrate 400 with the desired primary electron beam 21, and a secondary electron image of the secondary electron beam 301 can be generated. By performing this operation for the required number or positions of primary electron beams, multiple secondary electron images necessary for beam adjustment can be obtained. For example, multiple secondary electron images obtained by scanning with the central primary electron beam and the four corner primary electron beams can be acquired.

[0099] The contents of each step from the processing area setting step (S108) onward are the same as those described above.

[0100] Thus, it is also preferable to scan the primary electron beam one by one and create multiple secondary electron images at different times.

[0101] As described above, according to Embodiment 1, the beam size irradiated onto the sample surface can be brought closer to an optimal state.

[0102] In the above description, the series of "~circuits" include processing circuits, which include electrical circuits, computers, processors, circuit boards, quantum circuits, or semiconductor devices. Furthermore, each "~circuit" may use a common processing circuit (the same processing circuit), or it may use different processing circuits (separate processing circuits). The program that causes the processor, etc., to run may be recorded on a recording medium such as a magnetic disk drive, magnetic tape drive, FD, or ROM (read-on memory). For example, the position circuit 107, comparison circuit 108, reference image creation circuit 112, and beam adjustment circuit may be composed of at least one of the processing circuits described above.

[0103] The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples.

[0104] Furthermore, while descriptions of the device configuration, control methods, and other aspects not directly necessary for explaining the present invention have been omitted, the necessary device configuration and control methods can be appropriately selected and used.

[0105] Furthermore, all electron beam adjustment methods, multi-electron beam position evaluation methods, and electron beam image acquisition devices that incorporate elements of the present invention and can be appropriately modified by those skilled in the art are included within the scope of the present invention. [Explanation of Symbols]

[0106] 10 Primary electron beam 20. Multi-primary electron beam 22 holes 29 Sub-irradiation area 30 frame area 31 frame images 32 Stripe Area 33 Rectangular area 34 Irradiation area 50,52,56 storage device 54 Frame Image Creation Section 57 Alignment section 58 Comparison Section 60 Processing area setting unit 62 Spatial frequency image generation unit 64 Signal Area Calculation Unit 68 Processing area determination unit 70 Vector Calculation Unit 72 Vector sum calculation unit 74 Judgment section 100 Inspection device 101 circuit board 102 Electron beam column 103 Laboratory 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 Monitors 118 memory 119 Printer 120 bus 122 Laser length measuring system 123 Chip Pattern Memory 124 Lens control circuit 126 Blanking control circuit 128 Deflection control circuit 130 Retarding control circuit 132 Separator control circuit 134 Beam adjustment circuit 142 Stage drive mechanism 148 Voltage-controlled power supply 150 Image acquisition mechanism 151 Primary electron optical system 152 Secondary electron optical system 160 Control System Circuits 200 electron beam 201 Electron Gun 202, 205, 207 Electromagnetic lenses 203 Molded aperture array substrate 208 Deflector 211,212 Deflector 213 Limiting Aperture Substrate 214 Beam Separator 216 Mirror 218 Deflector 222 Multi-detector 224 Electromagnetic Lens 226 Deflector 240 Beam Selective Aperture Substrate 242 Electromagnetic Lens 244 detectors 300 Multi-Secondary Electron Beam 400 evaluation boards

Claims

1. The process involves scanning the sample with a primary electron beam, A step of detecting a secondary electron beam emitted from the sample due to the aforementioned scanning, A step of obtaining parameters from the secondary electron image obtained from the detection results of the secondary electron beam, A step of adjusting the incidence angle of the primary electron beam onto the sample using the aforementioned parameters, An electron beam adjustment method characterized by comprising the following features.

2. The process further comprises setting a plurality of small regions in the secondary electronic image, The electron beam tuning method according to claim 1, characterized in that a vector from the center of the secondary electron image to a small region among the plurality of small regions where an image was obtained with a beam having a smaller beam area is obtained as the parameter.

3. The electron beam adjustment method according to claim 1 or 2, characterized in that the incidence angle is adjusted so that the parameter or the value obtained using the parameter is less than or equal to an allowable value.

4. A multi-primary electron beam is used as the primary electron beam. The process of setting multiple sub-regions in each of the multiple secondary electron images using multiple secondary electron images corresponding to multiple primary electron beams from the aforementioned multi-primary electron beam, For each secondary electron image, the process involves calculating a vector from the center of the secondary electron image to the small region among the multiple small regions where an image was obtained with a beam having a smaller beam area, The process involves calculating the sum of the vectors obtained from each secondary electron image, Furthermore, The electron beam adjustment method according to claim 1, characterized in that the incident angle is adjusted so that the sum of the vectors is less than or equal to an allowable value.

5. The process involves scanning the sample with a multi-primary electron beam, A step of detecting the multi-secondary electron beam emitted from the sample due to the scanning, The process involves setting multiple sub-regions in each of the multiple secondary electron images using multiple secondary electron images obtained from the detection results of multiple secondary electron beams among the aforementioned multi-secondary electron beams, For each secondary electron image, the process involves determining the small region from among the plurality of small regions for which an image was obtained with a beam having a smaller beam area, For each secondary electron image, the process involves calculating a vector from the center of the secondary electron image to a determined small region, The process involves calculating and outputting the sum of the vectors obtained from each secondary electron image. A method for evaluating the position of multiple electron beams, characterized by comprising the following features.

6. A stage on which the sample is placed, A first deflector that scans the sample with the primary electron beam by beam deflection, A detector for detecting a secondary electron beam emitted from the sample due to the aforementioned scanning, A parameter acquisition unit that uses a secondary electron image obtained from the detection results of the secondary electron beam to acquire parameters from the secondary electron image, A second deflector adjusts the incident angle of the primary electron beam onto the sample by beam deflection using the aforementioned parameters, An electron beam image acquisition apparatus characterized by being equipped with the following features.

Images