Multibeam image acquisition system and drift correction method for multi-secondary electron beams

Abstract

A multi-beam image acquisition device according to one aspect of the present invention is characterized by comprising: a deflector which, in a state in which a prescribed period elapses from an irradiation start of multiple primary electron beams, causes at least one detector among a detector array to detect a signal waveform through beam deflection of multiple secondary electron beams, the signal waveform being formed due to an incident position of the detector where a secondary electron beam is incident and detected, the detector array detecting the multiple secondary electron beams emitted by irradiating an object with the multiple primary electron beams; a deviation amount calculation circuit which uses the signal waveform formed due to the incident position of the at least one detector to calculate a deviation amount of the incident position; and a corrector which corrects the incident position of the multiple secondary electron beams with respect to the detector array so as to reduce the deviation amount.

Description

[Technical Field]

[0001] This application claims priority over JP2022-187096 (application number), which was filed in Japan on November 24, 2022. All contents of JP2022-187096 are incorporated into this application by reference.

[0002] The present invention relates to a multibeam image acquisition device and a drift correction method for multiple secondary electron beams. For example, it relates to a multibeam inspection device that performs pattern inspection using secondary electron images caused by irradiation with multiple primary electron beams. [Background technology]

[0003] In recent years, with the increasing integration and capacity of large-scale integrated circuits (LSIs), the circuit line width required for semiconductor devices has been getting narrower and narrower. Furthermore, improving yield is essential for the production of LSIs, which incur significant manufacturing costs. However, as exemplified by 1-gigabit class DRAM (random access memory), the patterns constituting LSIs are on the order of submicrons to nanometers. In recent years, 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, high-precision imaging is necessary to inspect defects in ultrafine patterns transferred onto semiconductor wafers.

[0004] In the inspection device, for example, a multi-primary electron beam is used to scan the substrate to be inspected, separating the multi-secondary electron beam emitted from the substrate from the trajectory of the multi-primary electron beam. Then, the multi-secondary electron beam is detected by a detector, and a pattern image is captured.

[0005] In order to image each secondary electron beam with a multi-detector, it is necessary to guide the separated multi-secondary electron beams to their respective detectors. High-resistance contaminants adhere to the components of the secondary electron optical system during the operation of the inspection device. When scattered electrons and secondary electron beams that have spread out due to blurring are incident on these contaminants, charge accumulates. This generates an electric field, which bends the trajectory of the secondary electrons. As a result, the incident position of the secondary electron beam shifts from the desired position on the detector. This problem is not limited to inspection devices, but can occur similarly in all devices that detect multi-secondary electron beams and acquire secondary electron images.

[0006] Here, although not an inspection device, a technique has been disclosed in which a test mark is placed on the region above the objective aperture through which the primary electron beam of a single beam deflected by a blanker passes in an electron beam lithography system. Then, the amount of drift in the beam position of the primary electron beam is calculated from the signal from the detector of secondary electrons generated when the primary electron beam is deflected by the blanker, and the deflector is corrected as needed (see, for example, Patent Document 1). However, in the device configuration of such a method, the distance between the secondary electron generation site and the detector is short, and the concept of charge-up of the secondary electron optical system does not exist. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 09-115475 [Overview of the project] [Problems that the invention aims to solve]

[0008] Therefore, one aspect of the present invention provides an apparatus and method capable of correcting the misalignment of the incident position of a multi-secondary electron beam to a detector caused by charge-up of the secondary electron optical system. [Means for solving the problem]

[0009] A multi-beam image acquisition device according to one aspect of the present invention includes a stage on which an object irradiated with a multi-primary electron beam is placed, a primary electron optical system that irradiates the object with a multi-primary electron beam, a detector array that detects a multi-secondary electron beam emitted due to the object being irradiated with the multi-primary electron beam, a secondary electron optical system that guides the multi-secondary electron beam to the detector array, a deflector that causes a signal waveform resulting from the incident position of the secondary electron beam detected by at least one detector of the detector array that detects the multi-secondary electron beam emitted due to the object being irradiated with the multi-primary electron beam in a state where a predetermined period has elapsed since the start of irradiation of the multi-primary electron beam to be detected by the detector by deflecting the multi-secondary electron beam, a deviation amount calculation circuit that calculates the deviation amount of the incident position using the signal waveform resulting from the incident position on at least one detector, a corrector that corrects the incident position of the multi-secondary electron beam to the detector array so that the deviation amount becomes small, and is characterized by including 、 The deflector causes the detector to detect the signal waveform by scanning the detector with the secondary electron beam detected by the detector. The aforementioned deviation calculation circuit uses the signal waveform detected by scanning with the deflector after the predetermined period has elapsed and the secondary electron beam has drifted, to calculate the deviation from the signal waveform obtained when the secondary electron beam has not drifted. This is the feature.

[0010] A method for correcting the drift of a multi-secondary electron beam according to one aspect of the present invention includes irradiating with a multi-primary electron beam Object and detecting, with a detector array, a multi-secondary electron beam emitted due to Object being irradiated with the multi-primary electron beam, <000​ The amount of deviation in the incident position is calculated using the signal waveform caused by the incident position of at least one detector. The incidence position of the multi-secondary electron beam onto the detector array is corrected to minimize the amount of misalignment. death, By using a deflector, the secondary electron beam detected by the detector is scanned over the detector, thereby causing the detector to detect the signal waveform. Using the signal waveform detected by scanning with the deflector after the predetermined period has elapsed and drift has occurred in the secondary electron beam, the deviation from the signal waveform obtained when no drift occurs in the secondary electron beam is calculated. It is characterized by the following: [Effects of the Invention]

[0011] According to one aspect of the present invention, it is possible to correct the misalignment of the incident position of the multi-secondary electron beam to the detector caused by the charge-up of the secondary electron optical system. [Brief explanation of the drawing]

[0012] [Figure 1] This is a configuration diagram showing the configuration of the pattern inspection device in Embodiment 1. [Figure 2] This is a conceptual diagram showing the configuration of the molded aperture array substrate in Embodiment 1. [Figure 3] This figure shows an example of multiple chip regions formed on a semiconductor substrate in Embodiment 1. [Figure 4] This is a diagram illustrating the image acquisition process in Embodiment 1. [Figure 5] This figure shows an example of a secondary electron beam trajectory due to contamination in Embodiment 1. [Figure 6] This is a flowchart illustrating an example of the main steps of the inspection method in Embodiment 1. [Figure 7] This is a diagram showing an example of the configuration within the comparison circuit in Embodiment 1. [Figure 8] This is a block diagram showing an example of the configuration within the beam adjustment circuit in Embodiment 1. [Figure 9] This figure shows an example of a substrate and mark in Embodiment 1. [Figure 10] This figure shows another example of the substrate and mark in Embodiment 1. [Figure 11] This diagram illustrates how to measure the amount of secondary electron beam incident position displacement in Embodiment 1. [Figure 12] This figure illustrates the positional relationship between the secondary electron beam incidence position and the detection element when secondary electron drift does not occur in Embodiment 1. [Figure 13] This figure shows an example of the signal intensity distribution of detection data when secondary electron drift does not occur in Embodiment 1. [Figure 14] This diagram illustrates the positional relationship between the secondary electron beam incidence position and the detection element when secondary electron drift occurs in Embodiment 1. [Figure 15] This figure shows an example of the signal intensity distribution of detection data when secondary electron drift occurs in Embodiment 1. [Figure 16] This figure shows an example of the distribution of incident position displacement of the secondary electron beam in Embodiment 1. [Figure 17] This figure shows an example of a configuration for performing translation correction in Embodiment 1. [Figure 18] This figure shows an example of a configuration for performing magnification correction or rotation correction in Embodiment 1. [Figure 19A] This figure shows another example of the configuration for performing focus correction in Embodiment 1. [Figure 19B] This figure shows an example of the signal intensity distribution for each of the multiple excitations in Embodiment 1. [Figure 19C] This figure shows an example of the deflection direction in Embodiment 1. [Figure 19D] This figure shows an example of the signal intensity distribution in the x and y directions due to multiple excitations in Embodiment 1. [Figure 20] This figure shows an example of a configuration for performing astigmatism correction in Embodiment 1. [Figure 21A] This figure shows an example of a configuration for performing distortion correction in Embodiment 1. [Figure 21B] This figure shows another example of the configuration for performing distortion correction in Embodiment 1. [Figure 21C] This figure shows another example of the configuration for performing distortion correction in Embodiment 1. [Figure 22] This figure shows an example of a configuration for performing individual corrections in Embodiment 1. [Figure 23] This is a block diagram showing an example of the configuration within the beam adjustment circuit in Embodiment 2. [Figure 24] This is a flowchart illustrating an example of the main steps of the inspection method in Embodiment 2. [Figure 25] This figure shows an example of a mark in Embodiment 2. [Figure 26] This figure shows an example of a signal waveform in Embodiment 2. [Figure 27] This is a diagram illustrating the method for calculating the mark center in Embodiment 2. [Figure 28] This figure shows another example of the mark in Embodiment 2. [Figure 29] This figure shows an example of performing parallel shift correction for a multi-primary electron beam in Embodiment 2. [Figure 30] This figure shows an example of performing rotational correction for a multi-primary electron beam in Embodiment 2. [Figure 31] This figure shows an example of performing magnification correction for a multi-primary electron beam in Embodiment 2. [Modes for carrying out the invention]

[0013] In the following embodiments, a multi-electron beam inspection device will be described as an example of a multi-electron beam image acquisition device. However, the image acquisition device is not limited to an inspection device; any device that acquires images using multiple beams is acceptable. [Embodiment 1]

[0014] 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 is an example of a multi-electron beam image acquisition apparatus. The inspection apparatus 100 includes an image acquisition mechanism 150 and a control system circuit 160 (control unit). 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. The electron beam column 102 contains an electron gun 201, an illumination lens 202, a shaped aperture array substrate 203, an electromagnetic lens 205, a single deflector 212, a limiting aperture substrate 213, an electromagnetic lens 206, an E×B separator 214 (separator), an electromagnetic lens 207 (objective lens), deflectors 208, 209, deflector 218, deflectors 225, 226, a multi-stage electromagnetic lens 224, deflector 227, deflector 228, a detector aperture array substrate 223, and a multi-detector 222. Furthermore, it is preferable to place a multipole lens 229 within the magnetic field of the multi-stage electromagnetic lens 224. Although the multi-stage electromagnetic lens 224 is composed of multiple electromagnetic lenses as described later, it is also acceptable to use a single-stage electromagnetic lens instead of the multi-stage electromagnetic lens 224.

[0015] The primary electron optical system 151 (illumination optical system) is composed of an electron gun 201, an illumination lens 202, a molded aperture array substrate 203, an electromagnetic lens 205, a single deflector 212, a limiting aperture substrate 213, an electromagnetic lens 206, an E×B separator 214 (separator), an electromagnetic lens 207, and deflectors 208 and 209. The secondary electron optical system 152 (detection optical system) is composed of an electromagnetic lens 207, an E×B separator 214, a deflector 218, deflectors 225 and 226, and a multi-stage electromagnetic lens 224.

[0016] Furthermore, the deflector 227 (an example of a measurement mechanism) functions as a measuring deflector. Also, the deflector 228 is an example of a corrector. In addition, the multi-stage electromagnetic lens 224 is part of the secondary electron optical system 152 and also functions as another example of a corrector. Furthermore, the multipole lens 229 is another example of a corrector.

[0017] The multi-detector 222 has multiple detection elements arranged in an array (grid) configuration. Multiple openings are formed in the detector aperture array substrate 225 at the array pitch of the multiple detection elements. The multiple openings are formed, for example, in a circular shape. The center position of each opening is formed to match the center position of the corresponding detection element. In addition, the size of the openings is formed to be smaller than the area size of the electron detection surface of the detection element.

[0018] A stage 105, movable in at least the XY direction, is arranged inside the inspection chamber 103. The 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. If the substrate 101 is a semiconductor substrate, multiple chip patterns (wafer dies) are formed on the semiconductor substrate. If the substrate 101 is an exposure mask substrate, a chip pattern is 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 substrate 101 is placed on the stage 105, for example, with the pattern-forming surface facing upwards. Also on the stage 105 is a mirror 216 that reflects laser light for laser measurement emitted from a laser measurement system 122 located outside the inspection chamber 103. Also on the stage 105 is a mark 111 positioned at the same height as the surface of the substrate 101. For example, a cross pattern is formed on Mark 111.

[0019] 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.

[0020] 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, E×B separator control circuit 132, beam adjustment circuit 134, storage device 109 such as a magnetic disk drive, monitor 117, memory 118, and printer 119. The deflection control circuit 128 is connected to DAC (digital-to-analog conversion) amplifiers 143, 144, 145, 146, 147, 149, and DC power supply 148. DAC amplifier 146 is connected to deflector 208, and DAC amplifier 144 is connected to deflector 209. DC power supply 148 is connected to deflector 218. DAC amplifier 147 is connected to deflector 225. DAC amplifier 149 is connected to deflector 226. DAC amplifier 145 is connected to deflector 228. DAC amplifier 143 is connected to deflector 227.

[0021] Furthermore, if the multipole lens 229 is placed within the magnetic field of the multi-stage electromagnetic lens 224, the multipole lens control circuit 130 is connected to the control computer 110 via the bus 120. The multipole lens 229 is then controlled by the multipole lens control circuit 130.

[0022] 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.

[0023] Electromagnetic lenses 202, 205, 206, 207, and multi-stage electromagnetic lens 224 are controlled by lens control circuit 124. The collective deflector 212 is composed of two or more electrodes and is controlled by blanking control circuit 126 via a DAC amplifier (not shown) for each electrode. The deflector 209 is composed of four or more electrodes and is controlled by deflection control circuit 128 via a DAC amplifier 144 for each electrode. The deflector 208 is composed of four or more electrodes and is controlled by deflection control circuit 128 via a DAC amplifier 146 for each electrode. The deflector 225 is composed of four or more electrodes and is controlled by deflection control circuit 128 via a DAC amplifier 147 for each electrode. The deflector 226 is composed of four or more electrodes and is controlled by deflection control circuit 128 via a DAC amplifier 149 for each electrode. Furthermore, the deflector 227 is composed of four or more electrodes, and each electrode is controlled by the deflection control circuit 128 via the DAC amplifier 143. Similarly, the deflector 228 is composed of four or more electrodes, and each electrode is controlled by the deflection control circuit 128 via the DAC amplifier 145.

[0024] The deflector 218 (bender) is composed of, for example, multiple opposing electrodes formed in an arc-shaped cylindrical shape, and is controlled by a deflection control circuit 128 via a DC power supply 148. Alternatively, the deflector 218 may be composed of four or more electrodes, and each electrode may be controlled by the deflection control circuit 128 via a DC power supply 148 to improve the uniformity of the deflection electric field.

[0025] The E×B separator 214 is controlled by the E×B separator control circuit 132.

[0026] 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.

[0027] Here, Figure 1 shows the configuration necessary to explain Embodiment 1. The inspection device 100 may also have other configurations that are normally necessary.

[0028] 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 23 × 23 holes (openings) 22 are formed. Each hole 22 is formed as a rectangle of the same dimensions and shape. Alternatively, they may be circles with the same outer diameter. A multi-primary electron beam 20 is formed by a portion of the electron beam 200 passing through each of these multiple holes 22. The molded aperture array substrate 203 is an example of a multi-beam formation mechanism that forms a multi-primary electron beam 20. In this example, an optical system that reduces and transfers the image of the molded aperture array onto the material surface is shown as an example. Alternatively, a lens array can be provided downstream of the molded aperture array, causing the array of light source images to be imaged downstream of the lens array, and the resulting light source image array to be reduced and transferred onto the sample surface.

[0029] 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 device 100 will be described below.

[0030] The electron beam 200 emitted from the electron gun 201 (emission source) is refracted by the electromagnetic lens 202, illuminating the entire molded aperture array substrate 203. As shown in Figure 2, multiple holes 22 (openings) are formed in the molded aperture array substrate 203, and the electron beam 200 illuminates the region containing all of the multiple holes 22. A multi-primary electron beam 20 is formed as each portion of the electron beam 200 irradiated at the location of the multiple holes 22 passes through each of the multiple holes 22 in the molded aperture array substrate 203.

[0031] The formed multi-primary electron beam 20 is refracted by electromagnetic lenses 205 and 206, respectively, and proceeds to the E×B separator 214, which is positioned at the height of the intermediate image plane (image plane conjugate position: IIP) of each beam of the multi-primary electron beam 20, while repeatedly creating intermediate images and crossovers. After passing through the E×B separator 214, it proceeds to the electromagnetic lens 207. Furthermore, by placing a restricting aperture substrate 213 with limited passage holes near the crossover position of the multi-primary electron beam 20, scattered beams can be shielded. In addition, the entire multi-primary electron beam 20 can be blanked by deflecting the entire multi-primary electron beam 20 collectively with a single deflector 212 and shielding the entire multi-primary electron beam 20 with the restricting aperture substrate 213.

[0032] When the multi-primary electron beam 20 is incident on 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 irradiates the substrate 101 with the multi-primary electron beam 20. In this way, the primary electron optical system 151 illuminates the substrate 101 with the multi-primary electron beam 20.

[0033] The multi-primary electron beam 20, focused onto the substrate 101 (sample) surface by the electromagnetic lens 207, is deflected collectively by the deflectors 208 and 209, and each beam is directed to its respective irradiation position on the substrate 101. In this way, the primary electron optical system 151 illuminates the substrate 101 with the multi-primary electron beam 20.

[0034] When the multi-primary electron beam 20 is irradiated to a desired location on the substrate 101, a bundle of secondary electrons (multi-secondary electron beam 300) containing reflected electrons is emitted from the substrate 101 as a result of the irradiation by the multi-primary electron beam 20. A secondary electron beam corresponding to each beam of the multi-primary electron beam 20 is emitted.

[0035] The multi-secondary electron beam 300 emitted from the substrate 101 passes through the electromagnetic lens 207 and proceeds to the E×B separator 214.

[0036] The E×B separator 214 separates the multi-secondary electron beam 300 from the orbit of the multi-primary electron beam 20.

[0037] The E×B separator 214 has multiple magnetic poles (electromagnetic deflection coils) with two or more poles using coils, and multiple electrodes (electrostatic deflection electrodes) with two or more poles. For example, two opposing magnetic poles and two opposing electrodes shifted in phase by 90° can be arranged. The arrangement is not limited to this. For example, the electrodes can also serve as magnetic poles, and four or eight electrode-magnetic poles can be arranged. The E×B separator 214 deflects the multi-secondary electron beam 300 to produce a separation effect. The E×B separator 214 generates a directional magnetic field using multiple magnetic poles. Similarly, it generates a directional electric field using multiple electrodes. Specifically, the E×B separator 214 generates an electric field E and a magnetic field B 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 propagation. For the multi-primary electron beam 20 entering the E×B separator 214 from above, the force FE due to the electric field and the force FB due to the magnetic field cancel each other out, and the multi-primary electron beam 20 travels straight downwards. In contrast, for the multi-secondary electron beam 300 entering the E×B separator 214 from below, the force FE due to the electric field and the force FB due to the magnetic field both act in the same direction, and the multi-secondary electron beam 300 is deflected in a predetermined direction, bending diagonally upwards and separating from the trajectory of the multi-primary electron beam 20.

[0038] The multi-secondary electron beam 300, which is bent diagonally upward and separated from the multi-primary electron beam 20, is guided to 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 is deflected by the deflector 218, further bending it, and proceeds to the multi-stage electromagnetic lens 224. The multi-secondary electron beam 300 is then 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 multi-stage electromagnetic lens 224. The multi-detector 222 (multi-secondary electron beam detector) detects the multi-secondary electron beam 300 that has been separated from the trajectory of the multi-primary electron beam 20. In other words, the multi-detector 222 detects the refracted and projected multi-secondary electron beam 300. The multi-detector 222 has multiple detection elements (e.g., diode-type two-dimensional sensors, not shown). Then, each beam of the multi-primary electron beam 20 collides with the detection element corresponding to each secondary electron beam of the multi-secondary electron beam 300 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.

[0039] Figure 3 shows an example of multiple chip regions formed on a semiconductor substrate in Embodiment 1. In the example in Figure 3, the substrate 101 is shown as a semiconductor wafer. Multiple chips (wafer dies) 332 are formed in a two-dimensional array in the inspection region 330 of the substrate 101. A mask pattern for one chip formed on an exposure mask substrate is transferred to each chip 332, reduced to, for example, 1 / 4 of its original size by an exposure apparatus (stepper) not shown.

[0040] Figure 4 is a diagram illustrating the image acquisition process in Embodiment 1. As shown in Figure 4, the area of ​​each chip 332 is divided into a plurality of stripe areas 32 with a predetermined width in the y direction, for example. If the substrate 101 is a mask substrate, the pattern formation area (inspection area) formed on the mask is divided into a plurality of stripe areas 32 with a predetermined width in the y direction, for example.

[0041] The scanning operation by the image acquisition mechanism 150 is performed, for example, for each stripe region 32. For example, the scanning operation of the stripe region 32 is advanced in the x direction relative to the stage 105 while moving the stage 105 in the -x direction. Each stripe region 32 is divided into multiple rectangular regions 33 in the longitudinal direction. The movement of the beam to the target rectangular region 33 is performed by simultaneous deflection of the entire multi-primary electron beam 20 by two stages of deflectors 208, 209 (electrostatic deflectors).

[0042] The example in Figure 4 shows, for example, the case of 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 (size in the x direction obtained by multiplying the x-direction beam pitch of the multi-primary electron beam 20 on the surface of the substrate 10 by the number of beams in the x direction) × (size in the y direction obtained by multiplying the y-direction beam pitch 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 x-direction beam pitch and the y-direction beam pitch in which 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 different sub-irradiation areas 29. Each primary electron beam 10 will irradiate the same position within its assigned sub-irradiation area 29. The two-stage deflectors 208 and 209 deflect the multi-primary electron beam 20 collectively, thereby scanning the patterned substrate 101 surface 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 collectively deflected multi-primary electron beam 20 by the two-stage deflectors 208 and 209. This operation is repeated, sequentially irradiating one sub-irradiation area 29 with one primary electron beam 10.

[0043] 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 4, 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 simultaneously by the two-stage deflectors 208 and 209 to move 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 simultaneous deflection of the entire multi-primary electron beam 20 by the two-stage deflectors 208 and 209. In this way, each primary electron beam 10 performs a scan operation and acquires a secondary electron image for each sub-irradiation region 29. By combining these secondary electron images for each sub-irradiation 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 performing image comparison, the sub-irradiation 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 4 shows a case where the sub-irradiation 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.

[0044] Furthermore, when the stage 105 moves continuously and irradiates the substrate 101 with the multi-primary electron beam 20, tracking operation is performed by simultaneous deflection using two-stage deflectors 208 and 209 so that the irradiation position of the multi-primary electron beam 20 follows the movement of the stage 105. As a result, the emission position of the multi-secondary electron beam 300 changes moment by moment with respect to the trajectory center axis of the multi-primary electron beam 20. Similarly, when scanning within the sub-irradiation area 29, the emission position of each secondary electron beam changes moment by moment within the sub-irradiation area 29. To irradiate each secondary electron beam whose emission position has changed in this way into the corresponding detection area of ​​the multi-detector 222, for example, the two-stage deflectors 225 and 226 simultaneously deflect the multi-secondary electron beam 300. In other words, the deflectors 225 and 226 fix the position of the multi-secondary electron beam 300 on the detection surface of the multi-detector 222, which fluctuates due to scanning with the multi-primary electron beam 20, by deflecting the multi-secondary electron beam back. This allows each secondary electron beam to be detected by the corresponding detection element of the multi-detector 222. Note that the deflectors 225 and 226 are not limited to two-stage deflectors, but may also be configured as single-stage deflectors.

[0045] Figure 5 shows an example of a secondary electron beam trajectory due to contamination in Embodiment 1. As shown in Figure 5, high-resistance contaminants adhere to the surface of components constituting the secondary electron optical system 152 (for example, the deflector 225) during the operation of the inspection device 100. The components to which contaminants adhere are not limited to the deflector 225, but also other components constituting the secondary electron optical system 152 and the inner surface of the microscope tube.

[0046] Furthermore, when scattered electrons and secondary electron beams (peripheral electrons) spread out by blurring enter these contaminants, charge accumulates. This generates an electric field, which bends the trajectory of the secondary electrons. As a result, the trajectory of the secondary electron beam deviates from the original trajectory adjusted by calibration. In other words, drift occurs over time. This caused a problem where the incident position of the secondary electron beam shifted from the desired position on the detector. Therefore, Embodiment 1 corrects this drift of the secondary electron beam. Embodiment 1 describes, for example, the case in which drift is corrected between the start and end of inspection. In other words, it describes the case in which drift is corrected between the start and end of image acquisition of a single substrate 101.

[0047] Figure 6 is a flowchart showing an example of the main steps of the inspection method in Embodiment 1. In Figure 6, the inspection method in Embodiment 1 performs a series of steps: a scanning step (S102), a comparison step (S104), a determination step (S106), a determination step (S108), a secondary electron beam incidence position displacement measurement step (S120), a determination step (S122), and a secondary electron beam incidence position correction step (S124).

[0048] As a scanning process (S102) (image acquisition process), the image acquisition mechanism 150 scans the object (in this case, the substrate 101) with the multi-primary electron beam 20. Here, the image acquisition mechanism 150 scans each stripe region 32 with the multi-primary electron beam 20. As described above, the primary electron optical system 151 irradiates the object (in this case, the substrate 101) with the multi-primary electron beam 20. The multi-secondary electron beam 300 emitted as a result of the substrate 101 being irradiated with the multi-primary electron beam 20 is guided by the secondary electron optical system 152 to the multi-detector 222 (detector array). The guided multi-secondary electron beam 300 is then detected by the multi-detector 222 (detector array). 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 detected signal of the multi-secondary electron beam 300. Specifically, the detection data of secondary electrons for each pixel within 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 into digital data by an A / D converter (not shown) and stored in the chip pattern memory 123. The obtained measured image data is then transferred to the comparison circuit 108 along with information indicating each position from the position circuit 107.

[0049] Figure 7 is a diagram showing an example of the configuration within the comparison circuit in Embodiment 1. In Figure 7, 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.

[0050] In the comparison step (S104), the comparison circuit 108 compares the acquired secondary electron image with a predetermined reference image. Specifically, it operates as follows, for example.

[0051] The measurement image data (beam image) transferred to the comparison circuit 108 is stored in the storage device 50.

[0052] The frame image creation unit 54 then creates a frame image 31 for each of the multiple frame regions 30 obtained by further dividing the image data of the sub-irradiation region 29 acquired by the scanning operation of each primary electron beam. The frame region 30 is then used as the unit region 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] Next, the reference image creation circuit 112 applies a filter to the design image data of the design pattern, which is image data of the shape, using a predetermined filter function. This makes it possible to match the design image data, which is digital image data of the design side with image intensity (grayscale value), 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. The reference image data transferred to the comparison circuit 108 is stored in the storage device 52.

[0057] 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.

[0058] The comparison unit 58 then compares the secondary electronic image of the substrate 101 placed on the stage 105 with a predetermined image. Specifically, the comparison unit 58 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 whether there are any defects, such as shape defects. For example, if the difference in gradation value between pixels 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.

[0059] In addition to the die-database inspection described above, it is also preferable to perform die-die inspection, which involves comparing measurement image data of the same pattern captured at different locations on the same substrate. Alternatively, inspection can be performed using only the measurement images of the product itself.

[0060] The above operation will be repeated for all stripe areas 32.

[0061] Figure 8 is a block diagram showing an example of the configuration within the beam adjustment circuit in Embodiment 1. In Figure 8, the beam adjustment circuit 134 includes a determination unit 60, an incident position shift amount measurement processing unit 61, an incident position shift amount calculation unit 63, an incident position shift distribution creation unit 64, a determination unit 65, and a correction processing unit 66. Each of these "~units"—determination unit 60, incident position shift amount measurement processing unit 61, incident position shift amount calculation unit 63, incident position shift distribution creation unit 64, determination unit 65, and correction processing unit 66—has a processing circuit. Such processing circuits include, for example, electrical circuits, computers, processors, circuit boards, quantum circuits, or semiconductor devices. Each of these "~units" may use a common processing circuit (the same processing circuit) or different processing circuits (separate processing circuits). Information input to and output to the determination unit 60, the incident position deviation amount measurement processing unit 61, the incident position deviation amount calculation unit 63, the incident position deviation distribution creation unit 64, the determination unit 65, and the correction processing unit 66, as well as information being calculated, are stored each time in the memory 118 or a memory (not shown) in the beam adjustment circuit 134.

[0062] In the determination step (S106), the control computer 110 determines whether the inspection of the entire inspection area of ​​the substrate 101 has been completed. If it has been completed, the inspection process is terminated. If there are still stripe areas 32 that have not yet been inspected, the process proceeds to the determination step (S108).

[0063] As a determination step (S108), the determination unit 60 determines whether a specified time has elapsed since the start of the inspection. If the time has not yet elapsed, the process returns to the scanning step (S102), and each step from the scanning step (S102) to the determination step (S108) is repeated until the specified time has elapsed. If the specified time has elapsed, the process proceeds to the secondary electron beam incidence position displacement measurement step (S120). For example, while the comparison step (S104) of the nth (n is a natural number) stripe region 32 is being performed, the scanning step (S102) of the (n+1)th or (n+2)th stripe region 32 is executed. The specified time is set to be between several tens of minutes and several hours. For example, it is preferable to set the time required for scanning several stripes. For example, it may be set to 30 minutes.

[0064] As a secondary electron beam incident position displacement measurement process (S120) (drift measurement process), under the control of the incident position displacement measurement processing unit 61, the deflector 227 causes at least one detection element (detector) of the multi-detector 222, which detects the multi-secondary electron beam 300 emitted when the substrate 101 or mark 111 (another example of the target object) is irradiated by the multi-primary electron beam 20 after a specified time (determined) has elapsed since the start of irradiation of the multi-primary electron beam 20, to detect the signal waveform caused by the incident position of the secondary electron beam to the detection element by the beam deflection of the multi-secondary electron beam 300. Specifically, it operates as follows.

[0065] Figure 9 shows an example of a substrate and marks in Embodiment 1. Figure 9 shows the case where a mask substrate is used as the substrate 101. In Figure 9, in addition to the substrate 101, marks 111 are arranged on the stage 105 as described above. In the example of Figure 9, a case is shown where multiple marks 111 are arranged along one side of the substrate 101. It is preferable that each mark 111 be made of a material with a higher secondary electron yield than the substrate 101. For example, tungsten (W) is preferable. It is preferable that each mark 111 is formed to a size that allows the entire multi-primary electron beam 20 to be irradiated, and that the entire surface is made of a material with a high yield. Alternatively, as will be described later, each mark 111 may have multiple mark patterns equal to or greater than the number of multi-primary electron beams 20 arranged at the array pitch of the multi-primary electron beam 20. For example, a cross pattern is preferable as the mark pattern.

[0066] Starting from the first stripe region 32, marks 111 are placed adjacent to the stripe region 32 at intervals of several stripe regions 32 in the y-direction. For example, if marks 111 are placed at intervals of k stripe regions 32, the scan operation is repeated from the (nk+1)th stripe region 32 (where k is an integer greater than or equal to 3, and n is an integer greater than or equal to 0)th stripe region 32 to the (k+nk-1)th stripe region 32 (where k is an integer greater than or equal to 3) without performing the secondary electron beam incidence position displacement measurement process (S120). After the scan operation of the (k+nk)th stripe region 32 is completed, the secondary electron beam incidence position displacement measurement process (S120) is then performed at that y-direction position. In other words, after each scan operation of k stripe regions 32, the secondary electron beam incidence position displacement measurement process (S120) is performed at that y-direction position. Therefore, the specified time is set to be greater than or equal to the time required for the scan operation of (k-1) stripe regions 32, and less than the time required for the scan operation of k stripe regions 32. It is desirable to perform the secondary electron beam incidence position displacement measurement step (S120) after the scanning operation of the stripe region 32 is completed and before the scanning operation of the next stripe region 32.

[0067] Figure 10 shows another example of the substrate and mark in Embodiment 1. Figure 10 shows the case where a mask substrate is used as the substrate 101. In the example of Figure 10, for example, a single elongated mark 111 (e.g., a secondary electron generating film) is placed along one side of the substrate 101 in the y-direction where the stripe regions 32 are aligned. It is preferable that the mark 111 be made of a material with a higher secondary electron yield than the substrate 101. For example, tungsten (W) is preferable. The elongated mark 111 is formed with a width size that allows the entire multi-primary electron beam 20 to be irradiated, and it is preferable that the entire surface is made of a high-yield material. It is not necessary to place a pattern within the mark 111. Since the mark 111 is located adjacent to the longitudinal ends of all the stripe regions 32, for example, the number of times the secondary electron beam trajectory is corrected according to the substrate 101 can be arbitrarily changed.

[0068] Figure 11 is a diagram illustrating the method for measuring the incident position shift of the secondary electron beam in Embodiment 1. Figure 11 shows the trajectory of one of the outermost secondary electron beams 302 of the multi-secondary electron beam 300. It also shows an example of the trajectory 303 of the imaging system of the multi-secondary electron beam 300. Furthermore, in the example of Figure 11, it is shown that three electromagnetic lenses 42, 43, and 44 are used as the multi-stage electromagnetic lens 224.

[0069] In Figure 11, the measurement deflector 227 is positioned between the multi-stage electromagnetic lens 224 and the multi-detector 222 (and detector aperture array substrate 223). Without scanning the multi-primary electron beam 20, the deflector 227 collectively deflects the multi-secondary electron beam 300 emitted by irradiating each primary electron beam to a single point on the mark 111. This allows the deflector 227 to scan the multi-detector 222 with the multi-secondary electron beam 300. The example in Figure 11 shows the scanning of one of the outermost secondary electron beams 302 of the multi-secondary electron beam 300, but the other secondary electron beams are scanned in the same manner.

[0070] Figure 12 is a diagram illustrating the positional relationship between the secondary electron beam incidence position and the detection element when no secondary electron drift occurs in Embodiment 1. Figure 13 shows an example of the signal intensity distribution of detection data when no secondary electron drift occurs in Embodiment 1. For example, a multi-primary electron beam 20 is incident on mark 111 at the deflection center. If no drift occurs in the secondary electron trajectory, each secondary electron beam is incident on the corresponding detection element 40, for example, at the center position, at the deflection center of the deflector 227, through beam calibration before the start of device operation. In the example of Figure 12, the trajectory of the outer secondary electron beam 302 is shown. By deflecting the multi-secondary electron beam 300 with the deflector 227, the detection element 40 is scanned with the secondary electron beam 302. Here, it is deflected to a position outside the detection surface of the detection element 40. This allows the signal intensity distribution of the secondary electron beam 302 shown in Figure 13 to be measured. The signal intensity is high while the entire secondary electron beam 302 is detected by the detection surface of the detection element 40, and the signal intensity decreases as the amount of beam deflection increases and the amount it extends beyond the detection surface. Furthermore, the entire uniform portion of the signal intensity distribution with high signal intensity is detected within the deflection range of the deflector 227.

[0071] Figure 14 is a diagram illustrating the positional relationship between the secondary electron beam incidence position and the detection element when secondary electron position drift occurs in Embodiment 1. Figure 15 shows an example of the signal intensity distribution of detection data when secondary electron drift occurs in Embodiment 1. For example, a multi-primary electron beam 20 is incident on mark 111 at the deflection center. If drift occurs in the secondary electron trajectory, each secondary electron beam is incident at a position off-center, for example, on the corresponding detection element 40 at the deflection center of the deflector 227. In the example in Figure 14, the trajectory of the outer secondary electron beam 302 is shown. By deflecting the multi-secondary electron beam 300 with the deflector 227, the detection element 40 is scanned with the secondary electron beam 302. Here, it is deflected to a position off-center from the detection surface of the detection element 40. This allows the signal intensity distribution of the secondary electron beam 302 shown in Figure 15 to be measured. The signal intensity is high while the entire secondary electron beam 302 is detected on the detection surface of the detection element 40, and the signal intensity decreases as the amount of beam deflection increases and the beam extends beyond the detection surface. If the trajectory of the secondary electron beam is shifted due to drift, the entire uniform portion of the signal intensity distribution with high signal intensity will be detected as not falling within the deflection range of the deflector 227.

[0072] The incident position shift calculation unit 63 (shift calculation circuit) calculates the shift in the incident position to at least one detection element 40 (detector) using the signal waveform resulting from the incident position to the detection element 40. Specifically, the incident position shift calculation unit 63 calculates the shift amount dx between the signal intensity distribution detected in Figure 13 and the signal intensity distribution detected in Figure 15. The shift amount dx between the reference signal intensity distribution detected in Figure 13 and the signal intensity distribution detected in Figure 15 after a predetermined period has elapsed is measured as the secondary electron beam incident position shift amount. Here, the shift amount in the x-direction is shown, but the shift amount in the y-direction is measured similarly.

[0073] The deflector 227 causes the multi-detector 222, which detects the multi-secondary electron beam 300 emitted due to the irradiation of the mark 111 (object) by the multi-primary electron beam 20 after a predetermined period has elapsed since the start of irradiation of the multi-primary electron beam 20, to detect a plurality of signal waveforms caused by the incident positions of the plurality of secondary electron beams detected by a plurality of detection elements among the plurality of detection elements, by deflecting the multi-secondary electron beam 300. In other words, for the other secondary electron beams other than the outer peripheral secondary electron beam 302 of the multi-secondary electron beam 300, the amount of displacement of the secondary electron beam incident position is measured in the same manner. Therefore, the incident position displacement amount calculation unit 63 (displacement amount calculation circuit) calculates the amount of displacement of the plurality of incident positions to the plurality of detectors using the plurality of signal waveforms caused by the incident positions to the plurality of detection elements. The method of calculating the amount of displacement of each incident position is the same as the above-described content.

[0074] Here, as the displacement of the incident position over the entire multi-secondary electron beam 300, a displacement due to parallel movement (translation), a displacement due to rotation, a displacement due to magnification, or a displacement due to distortion occurs. The tendency of these displacements can be grasped by creating a displacement amount distribution.

[0075] Therefore, the incident position displacement distribution creation unit 64 (distribution creation circuit) creates an incident position displacement distribution using the amounts of displacement of the plurality of incident positions. In other words, the incident position displacement distribution creation unit 64 creates an incident position displacement distribution using the amount of displacement of the incident position 11 of each secondary electron beam. Further, it is preferable that the incident position displacement distribution creation unit 64 approximates the incident position displacement distribution by a polynomial and obtains it as a function. For example, it is approximated by a quadratic polynomial represented by the following equations (1) and (2). It may also be approximated by a polynomial of the third degree or higher. a ij , b ij are coefficients. (1) Δx = a 00 + a 10 x + a 01 y + a 20 x 2 + a 11 xy + a 02 y 2 (2) Δy=b 00 +b 10 x+b 01 y+b 20 x 2 +b 11 xy+b 02 y 2

[0076] The distribution of the displacement of the incident position 11 of each secondary electron beam is approximated by the least squares method, and each coefficient a ij , b ij We find the coefficient a. 00 , b 00 The first term corresponds to the displacement of translation. The first-order term corresponds to the displacement of rotation, the displacement of magnification, and the first-order distortion. The second-order term corresponds to the higher-order distortion.

[0077] Figure 16 shows an example of the distribution of incident position displacement of the secondary electron beam in Embodiment 1. As shown in Figure 16, in a normal state where no drift occurs, the incident position 11 of each secondary electron beam is, for example, the center position of each detection element 40. In contrast, when drift occurs, the incident position 11 of each secondary electron beam is shifted from, for example, the center position of each detection element 40. By creating an incident position displacement distribution, it can be seen that the trend of incident position displacement is due to parallel (translational) displacement, rotational displacement, magnification displacement, or distortion displacement, as shown in Figure 16. Furthermore, the amount of displacement in each displacement trend can be seen.

[0078] As a determination step (S122), the determination unit 65 determines whether the incident position displacement Δ is greater than the threshold th. It is preferable to use statistical values ​​such as the maximum value, average value, or median value of the displacement dx of the incident position 11 of each secondary electron beam as the incident position displacement Δ. Alternatively, the incident position displacement Δ may be the displacement of the incident position 11 of one or more predetermined secondary electron beams. For example, the incident position displacement Δ may be the displacement of the incident position 11 of the central secondary electron beam of the multi-secondary electron beam 300. Alternatively, it is preferable to determine the incident position shape of the multi-secondary electron beam 300 using the displacement amounts of the incident position 11 of the four secondary electron beams at the four corners on the outer periphery of the multi-secondary electron beam 300, and then determine the x-direction displacement, y-direction displacement, rotational displacement, and / or magnification displacement of the incident position shape of the multi-secondary electron beam 300 using the respective predetermined threshold values. If the incident position deviation Δ is not greater than the threshold th, the process returns to the scanning process (S102), and each step from the scanning process (S102) to the determination process (S122) is repeated until the incident position deviation Δ becomes greater than the threshold th. If the incident position deviation Δ is greater than the threshold th, the process proceeds to the secondary electron beam incident position correction process (S124).

[0079] As a secondary electron beam incidence position correction process (S124), under the control of the correction processing unit 66, the corrector corrects the incidence position of the multi-secondary electron beam 300 onto the multi-detector 222 so that the amount of deviation is reduced.

[0080] Figure 17 shows an example of a configuration for performing translation correction in Embodiment 1. In Figure 17, the corrector has a deflector 228 that translates the incident position of the multi-secondary electron beam 300 to the multi-detector 222. In other words, the deflector 228 is an example of a corrector that performs translation correction. In the example in Figure 17, it is shown that three electromagnetic lenses 42, 43, and 44 are used as the multi-stage electromagnetic lens 224. Each secondary electron beam is refracted by these three electromagnetic lenses 42, 43, and 44. The corrective deflector 228 corrects the trajectory of the multi-secondary electron beam 300 by beam deflection and translates the incident position to the multi-detector 222 by the amount of the displacement in the direction that corrects the displacement. This corrects the incident position of the multi-secondary electron beam 300 to the multi-detector 222. Here, it is preferable that the corrective deflector 228 is positioned on a plane perpendicular to the trajectory center axis at the crossover position of the multi-secondary electron beam 300. For example, it is preferable to place it at the final crossover position. This allows the multi-secondary electron beam 300 to be deflected at essentially one point, thereby suppressing aberrations caused by the deflection. Thus, the correction accuracy can be improved.

[0081] Alternatively, instead of using the deflector 228 for correction, parallel shift correction may be performed by shifting the orbital center axis of the multi-secondary electron beam 300 using an air-core alignment coil.

[0082] Figure 18 shows an example of a configuration for performing magnification correction or rotation correction in Embodiment 1. In Figure 18, the corrector has a multi-stage lens that corrects the magnification of the distribution of the incident position of the multi-secondary electron beam 300 to the multi-detector 222. The corrector also has a multi-stage lens that corrects the rotation of the distribution of the incident position of the multi-secondary electron beam 300 to the multi-detector 222. In other words, the multi-stage electromagnetic lens 224 is an example of a corrector that performs magnification correction or rotation correction. In the example in Figure 18, a case is shown in which three electromagnetic lenses 42, 43, and 44 are used as the multi-stage electromagnetic lens 224. Each secondary electron beam is refracted by these three electromagnetic lenses 42, 43, and 44 controlled by the lens control circuit 124. At that time, the multi-stage electromagnetic lens 224 corrects the trajectory of the multi-secondary electron beam 300 and corrects the incident position to the multi-detector 222 by the amount of displacement in the direction of correction of the displacement, thereby correcting the magnification or rotation. Since adjustment of three parameters—focus, magnification, and rotation—is necessary, it is preferable to arrange three or more electromagnetic lenses as a multi-stage electromagnetic lens 224.

[0083] Figure 19A shows another example of the configuration for performing focus correction in Embodiment 1. In Figure 19A, the electrostatic lens 230 is an example of a corrector that performs focus correction. In the example in Figure 19A, a case is shown in which three electromagnetic lenses 42, 43, and 44 are used as the multi-stage electromagnetic lens 224. The electrostatic lens 230 corrects the trajectory of the multi-secondary electron beam 300 and corrects the focal point of the incident position on the multi-detector 222 by the amount of the displacement in the direction that corrects the displacement. Electrostatic lenses can generally focus faster than electromagnetic lenses. Here, the corrective electrostatic lens 230 is preferably positioned on a plane perpendicular to the trajectory center axis at the crossover position of the multi-secondary electron beam 300. For example, it is preferably positioned at the final crossover position. This allows for focal correction while suppressing changes in magnification.

[0084] Alternatively, a quadrupole lens with three or more stops may be used to correct magnification and focus.

[0085] Up to this point, we have explained the correction of beam position drift. However, if charging occurs in the region through which the electron beam passes, an electrostatic lensing effect occurs due to the electric field associated with that charging. This effect manifests as a shift in focus depending on the distribution of the electric field. Not only does the focus shift isotropically, but anisotropy also appears in the shift in focus. As anisotropy, if the focal positions in two orthogonal directions are shifted, it manifests as astigmatism. Below, astigmatism will be explained assuming that the focal positions in the x and y directions are shifted. When a shift in focus occurs, the distribution of each beam of the multi-secondary electron beam 300 incident on the detector surface, i.e., beam blur, becomes larger. Considering one beam, if the magnitude of this beam blur is equal to or greater than the dimensions of the detector element used to detect the child beam of the multi-detector 222, the amount of secondary electron beam current received by the detector element becomes small. Alternatively, a part of this beam may be incident on an adjacent detector. When these phenomena occur, the measurement accuracy deteriorates. Correction is necessary to reduce the beam blur.

[0086] Figure 19B shows an example of the signal intensity distribution for multiple excitations in Embodiment 1. In Figure 19B, the vertical axis shows the signal intensity, and the horizontal axis shows the scan amount. Figure 19B shows an example of the signal intensity distribution at the initial excitation 0, and the signal intensity distributions at excitation -1 and excitation +1 before and after excitation 0. Figure 19C shows an example of the deflection direction in Embodiment 1. Figure 19D shows an example of the signal intensity distribution in the x and y directions due to multiple excitations in Embodiment 1. In Figure 19D, the vertical axis shows the signal intensity, and the horizontal axis shows the scan amount. Figure 19D shows an example of the signal intensity distribution at the initial excitation 0, and the signal intensity distribution in the x and y directions at excitations -2, -1, +1, and +2 before and after excitation 0. To measure the focal shift, multiple different excitation settings are applied to one of the objective lenses 42, 43, or 44, and the multi-secondary electron beam 300 is measured. The change in the signal obtained at each detector element 40 is then used to determine the focal position shift. The deflection is performed in four different directions, each shifted by 45 degrees, as shown in Figure 19C. The edges of the detector elements 40 can be used as measurement edges, or measurement apertures can be placed immediately upstream of each detector element 40. If changing the excitation of only one lens causes problems with the measurement of the focal position due to changes in magnification and rotation, the excitation of the three lenses is adjusted so that the waveform distribution on the detector element 40 is sharpest while keeping the magnification and rotation constant. The focal position without drift is determined by the combination of excitation settings of the three lenses. This is measured beforehand and a table is created; when shifting the focal position, this table is used to determine the excitation settings of the three lenses.

[0087] The following explains the case where there is no positional drift. If there is no anisotropy in the focus shift, the excitation that yields the sharpest distribution will deviate from the initial value, as shown in Figure 19B, for example. This focus shift is independent of direction. When anisotropy in the focus shift occurs in the x and y directions, the excitation that yields the sharpest distribution shifts in the x and y directions, as shown in Figure 19D. In the 45-degree direction, it falls somewhere in between. If isotropic focus misalignment occurs, adjust the detector element 40 using one of the objective lenses 42, 43, or 44 so that the waveform distribution on the detector element 40 is sharpest.

[0088] Figure 20 shows an example of a configuration for performing astigmatism correction in Embodiment 1. In Figure 20, the astigmatism corrector 232 is an example of a corrector that performs astigmatism correction. When the focal position in the x direction and the focal position in the y direction are different, correction with an electromagnetic lens becomes difficult. In this case, the astigmatism corrector 232 is used to adjust so that the focal points in the x direction and the y direction coincide. For example, it is preferable to use a multipole lens (stigmata) with 8 or more poles as the astigmatism corrector 232. Here, it is preferable to position the astigmatism corrector 232 for correction on a plane perpendicular to the orbital center axis at the crossover position of the multi-secondary electron beam 300. For example, it is preferable to position it at the final crossover position. This allows the forces in the x and y directions of the multi-secondary electron beam 300 to be applied while suppressing the generation of distortion in the multi-beam distribution, thereby improving the correction accuracy.

[0089] Figure 21A shows an example of a configuration for distortion correction in Embodiment 1. In Figure 21A, the corrector has a multipole lens that corrects the distortion of the distribution of incident positions of the multi-secondary electron beam 300 to the multi-detector 222. In other words, the multipole lens 234 is an example of a corrector that performs distortion correction. If distortion occurs in the incident position distribution shape of the entire multi-secondary electron beam 300, the multipole lens 234 corrects the distortion of the incident position distribution shape. It is preferable to use a multipole lens with four or more poles as the multipole lens 234. Here, it is preferable that the corrective multipole lens 234 be positioned at a conjugate position conjugate to the detection surface of the multi-detector 222 and on a plane perpendicular to the orbital central axis. For example, it is preferable to position it at the conjugate position closest to the multi-detector 222. This makes it possible to correct the distortion of the incident position distribution shape of the entire multi-secondary electron beam 300 while suppressing the occurrence of astigmatism in the image. In reality, distortion changes when astigmatism correction is performed, and astigmatism occurs when distortion correction is performed. Therefore, the following configuration is preferable.

[0090] Figure 21B shows another example of the configuration for performing distortion correction in Embodiment 1. As shown in Figure 21B, it is desirable to adjust both the astigmatism corrector 232 and the multipole lens 234 so that astigmatism correction and distortion correction can be achieved simultaneously.

[0091] Furthermore, even when astigmatism correction is performed and the image position matches, the difference between the x-direction magnification and the y-direction magnification can sometimes be a problem. This can be addressed by providing two or more stages of astigmatism correction to suppress the anisotropy of the magnification.

[0092] Figure 21C shows another example of the configuration for distortion correction in Embodiment 1. The example in Figure 21C shows a configuration in which a multipole lens 234 and two-stage astigmatism correctors 232 are arranged. The example in Figure 21C shows the case where the two-stage astigmatism correctors 232 are arranged with the multipole lens 234 in between. Also, as the multi-stage magnetic lens 224, for example, a six-stage electromagnetic lens is shown. For example, in an optical system as shown in Figure 21C, it is also possible to provide three or more correctors in order to achieve compatibility with distortion correction.

[0093] Figure 22 shows an example of a configuration for performing individual correction in Embodiment 1. In the example described above, a method for correcting the entire multi-secondary electron beam 300 at once was explained. However, there may be cases where there is no trend in the incident position deviation or focal deviation of each secondary electron beam, and they deviate independently. In that case, the correction cannot be fully corrected by correcting the multi-secondary electron beam 300 at once. In Figure 22, the corrector array 236 is an example of a corrector that performs individual correction. It is preferable to use a multipole lens array as the corrector array 236. In the example in Figure 22, it is shown that three electromagnetic lenses 42, 43, and 44 are used as the multi-stage electromagnetic lens 224. The corrector array 236 individually corrects the trajectory of the multi-secondary electron beam 300 and individually corrects the incident position to the multi-detector 222 by the amount of deviation in the direction of correction. Here, it is preferable that the corrector array 236 be placed within the magnetic field of the final electromagnetic lens 44 of the multi-stage electromagnetic lens 224. Furthermore, astigmatism can be corrected by generating a quadrupole field with the multipole lenses of the corrector array 236. If the corrector array 236 includes not only multipole lenses but also an Einzel lens array, it becomes possible to correct the focus misalignment of individual beams. Here, if the Einzel lens array is placed within a magnetic field lens, the focal position can be adjusted in both the forward and backward directions of propagation. Alternatively, the Einzel lens array can be adjusted by applying a constant voltage before the inspection, and then increasing or decreasing the voltage applied to the Einzel lenses to adjust the focal position forward or backward. Furthermore, an Einzel lens array can also be used to measure the focus shift, as explained in Figure 20. In this case, instead of changing the excitation of objective lenses 42, 43, and 44, the focal length is shifted by changing the voltage applied to the focus of the Einzel lens array.

[0094] After correcting for the incident position misalignment and focus misalignment, the process returns to the secondary electron beam incident position misalignment and focus misalignment measurement process (S120). This measures the corrected incident position misalignment and confirms that it is below the threshold, and then the process returns to the scanning process (S102). Generally, measurements and corrections that require changing the excitation of the lens take longer than measurements and corrections that use only a deflector. Therefore, if the frequency of measurements and corrections that require changing the excitation of the electromagnetic lens is not expected to be as high as those that use only a deflector, the frequency of measurements and corrections that require changing the excitation of the electromagnetic lens can be made lower than the frequency of measurements and corrections that use only a deflector without changing the excitation of the electromagnetic lens, thereby shortening the overall correction time. This is also true for corrections in the primary electron optical system 151 described in Embodiment 2.

[0095] As described above, according to Embodiment 1, the shift in the incident position of the multi-secondary electron beam 300 to the multi-detector 222 caused by the charge-up of the secondary electron optical system 152 can be corrected. [Embodiment 2]

[0096] Embodiment 1 described a configuration for correcting drift in the multi-secondary electron beam 300 caused by charge-up in the secondary electron optical system 152. Beam drift is not limited to the multi-secondary electron beam 300. Beam drift can also occur in the multi-primary electron beam 20 due to charge-up in the primary electron optical system 151. Embodiment 2 describes a configuration that, in addition to correcting the drift of the multi-secondary electron beam 300, also corrects the drift of the multi-primary electron beam 20.

[0097] The configuration of the inspection apparatus 100 in Embodiment 2 is the same as in Figure 1. Furthermore, the details described below are the same as in Embodiment 1, except for the points specifically described.

[0098] Figure 23 is a block diagram showing an example of the configuration within the beam adjustment circuit in Embodiment 2. Figure 23 is the same as in Figure 8, except that the beam adjustment circuit 134 also includes a determination unit 70, an incident position deviation measurement processing unit 71, an incident position deviation calculation unit 73, an incident position deviation distribution creation unit 74, a determination unit 75, and a correction processing unit 76. Each of the "~ section," such as the determination section 60, the incident position deviation measurement processing section 61, the incident position deviation calculation section 63, the incident position deviation distribution creation section 64, the determination section 65, the correction processing section 66, the determination section 70, the incident position deviation measurement processing section 71, the incident position deviation calculation section 73, the incident position deviation distribution creation section 74, the determination section 75, and the correction processing section 76, has a processing circuit. Such a processing circuit includes, for example, an electrical circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Each of the "~ section" may use a common processing circuit (the same processing circuit) or may use different processing circuits (separate processing circuits). Information input to and output to the determination unit 60, the incident position deviation amount measurement processing unit 61, the incident position deviation amount calculation unit 63, the incident position deviation distribution creation unit 64, the determination unit 65, the correction processing unit 66, the determination unit 70, the incident position deviation amount measurement processing unit 71, the incident position deviation amount calculation unit 73, the incident position deviation distribution creation unit 74, the determination unit 75, and the correction processing unit 76, as well as information being calculated, is stored each time in the memory 118 or a memory (not shown) in the beam adjustment circuit 134.

[0099] Figure 24 is a flowchart showing an example of the main steps of the inspection method in Embodiment 2. In Figure 24, the inspection method in Embodiment 2 is the same as in Figure 6, except that a primary electron beam incident position deviation measurement step (S110), a determination step (S112), and a primary electron beam incident position correction step (S114) are performed between the determination step (S108) and the secondary electron beam incident position deviation measurement step (S120).

[0100] Embodiment 2 further includes a step to correct the drift of the multi-primary electron beam 20, in addition to the steps of Embodiment 1. Then, after correcting the drift of the multi-primary electron beam 20, the drift (incident position shift) of the multi-secondary electron beam 300 is corrected.

[0101] The contents of each step, the scanning step (S102), the comparison step (S104), the determination step (S106), and the determination step (S108), are the same as in Embodiment 1.

[0102] As a primary electron beam incident position shift measurement process (S110), under the control of the incident position shift measurement processing unit 71, the deflectors 208 and 209 deflect the multi-primary electron beam 20 after a specified time (determined) has elapsed since the start of irradiation of the multi-primary electron beam 20, thereby scanning the mark 111 with the multi-primary electron beam 20. Then, the multi-secondary electron beam 300 emitted from the mark 111 is detected by the multi-detector 222. Since the multi-secondary electron beam 300 is deflected back by the deflectors 225 and 226, it can be detected at the same position on the detection element even when scanning with the primary electron beam. Furthermore, it is acceptable even if drift occurs in the secondary electron beam. Here, it is sufficient that detection is possible regardless of the incident position of the secondary electron beam incident on the detection element. Then, the signal intensity distribution of the secondary electron beam detected by the multi-detector 222 is used to measure the incident position of each of the multi-primary electron beams 20. Specifically, it operates as follows.

[0103] Figure 25 shows an example of a mark in Embodiment 2. In Figure 25, multiple mark patterns 113 are arranged in an array within the mark 111 at the array pitch of the multi-primary electron beams 20 on the substrate 101. In the example of Figure 25, 3 × 3 mark patterns 113 are arranged in an array for 3 × 3 multi-primary electron beams 20. In other words, the same number of mark patterns 113 as the number of multi-primary electron beams 20 are arranged in an array. For example, a cross pattern is preferably used as the mark pattern 113.

[0104] Each primary electron beam of the multi-primary electron beam 20 scans the corresponding cross-shaped line pattern portions on the paper in the upper, lower, left, and right directions. Then, the corresponding detection elements of the multi-detector 222 detect the secondary electron beams for each of the upper, lower, left, and right line pattern portions. As a result, the signal intensity distribution (signal waveform) of the secondary electron beams is obtained for each of the upper, lower, left, and right line pattern portions.

[0105] The incident position displacement calculation unit 73 calculates the incident position displacement for each primary electron beam. Specifically, it operates as follows.

[0106] Figure 26 shows an example of a signal waveform in Embodiment 2. For the upper, lower, left, and right line pattern portions, the center of the half-width of the obtained signal waveforms can be considered as the center of the line pattern portion in the width direction.

[0107] Figure 27 is a diagram illustrating the method for calculating the mark center in Embodiment 2. The incident position shift amount calculation unit 73 calculates the mark center using the center positions of the four line pattern portions in the upper, lower, left, and right directions. Specifically, the incident position shift amount calculation unit 73 calculates the average position of the center positions of the upper and lower line pattern portions as the x-coordinate of the center of the cross pattern, and the average position of the center positions of the left and right line pattern portions as the y-coordinate of the center of the cross pattern. Then, the incident position shift amount calculation unit 73 calculates the amount of shift between the deflection center position during scanning and the center position of the cross pattern as the incident position shift amount of the target primary electron beam.

[0108] Figure 28 shows another example of the mark in Embodiment 2. In Figure 28, multiple mark patterns 113 are arranged in an array within the mark 111 at a pitch that is an integer multiple of the array pitch of the multi-primary electron beams 20 on the substrate 101. The example in Figure 28 shows a case where 3 × 3 mark patterns 113 are arranged in an array for 5 × 5 multi-primary electron beams 20. In the example in Figure 28, multiple mark patterns 113 are arranged in an array at a pitch twice the array pitch of the multi-primary electron beams 20. In other words, fewer mark patterns 113 are arranged in an array than the number of multi-primary electron beams 20. For example, a cross pattern is preferably used as the mark pattern 113.

[0109] Multiple primary electron beams from the multi-primary electron beam 20 scan the corresponding cross-shaped line pattern portions on the paper in the upper, lower, left, and right directions. Then, the corresponding detection elements of the multi-detector 222 detect the secondary electron beams for each of the upper, lower, left, and right line pattern portions. As a result, the signal intensity distribution (signal waveform) of the secondary electron beams is obtained for each of the upper, lower, left, and right line pattern portions.

[0110] The incident position displacement calculation unit 73 calculates the incident position displacement for each primary electron beam that scans the mark pattern 113. The calculation method is the same as described above.

[0111] The incident position shift distribution creation unit 74 (distribution creation circuit) creates an incident position shift distribution for the multi-primary electron beam 20 using multiple shift amounts. In other words, the incident position shift distribution creation unit 74 creates an incident position shift distribution using the shift amount of the incident position of each primary electron beam. Furthermore, it is preferable for the incident position shift distribution creation unit 74 to approximate the incident position shift distribution with a polynomial and obtain it as a function. For example, it is approximated by a second-order polynomial shown in the following equations (3) and (4). It may also be approximated by a polynomial of order 3 or higher. ij d ij This is a coefficient. (3) Δx=c 00 +c 10 x+c 01 y+c 20 x 2 +c 11 xy+c 02 y 2 (4) Δy=d 00 +d 10 x+d 01 y+d 20 x 2 +d 11 xy+d 02 y 2

[0112] The distribution of the displacement of the incident position of each primary electron beam is approximated by the least squares method, and each coefficient c ij d ij We find the coefficient c. 00 d 00The first term corresponds to the displacement of translation. The first-order term corresponds to the displacement of rotation, the displacement of magnification, and the first-order distortion. The second-order term corresponds to the higher-order distortion.

[0113] By creating an incidence position displacement distribution for the multi-primary electron beam 20, it can be seen that the incidence position displacement trends are similar to those of the multi-secondary electron beam 300, consisting of parallel (translational) displacement, rotational displacement, magnification displacement, or distortion displacement. Furthermore, the amount of displacement for each displacement trend can be determined.

[0114] As a determination step (S112), the determination unit 75 determines whether the incident position displacement Δ′ of the multi-primary electron beam 20 is greater than the threshold th′. It is preferable to use statistical values ​​such as the maximum, average, or median of the incident position displacement amounts of each primary electron beam as the incident position displacement amount Δ′. Alternatively, the incident position displacement amount Δ′ may be the incident position displacement amount of one or more predetermined primary electron beams. For example, the incident position displacement amount of the central primary electron beam of the multi-primary electron beam 20 may be used as the incident position displacement amount Δ′. Alternatively, it is preferable to determine the incident position shape of the multi-primary electron beam 20 using the incident position displacement amounts of the four primary electron beams at the four corners on the outer periphery of the multi-primary electron beam 20, and then determine the x-direction displacement amount, y-direction displacement amount, rotational displacement amount, and / or magnification displacement amount of the incident position shape of the multi-primary electron beam 20, and make a determination using the respective predetermined threshold values. If the incident position displacement amount Δ′ is not greater than the threshold value th′, the process proceeds to the secondary electron beam incident position displacement amount measurement process (S120). If the incident position displacement amount Δ′ is greater than the threshold value th′, the process proceeds to the primary electron beam incident position correction process (S114).

[0115] As a primary electron beam incidence position correction step (S114), under the control of the correction processing unit 76, the deflectors 208 and 209 correct the incidence position of the multi-primary electron beam 20 onto the substrate 101 so as to reduce the amount of deviation. Specifically, the deflection control circuit 128 receives the incidence position deviation amount of each primary electron beam of the multi-primary electron beam 20 and corrects the deflection amount when deflecting the multi-primary electron beam 20 collectively so as to reduce the deviation of the incidence position of the multi-primary electron beam 20. Specifically, it offsets the original deflection amount by a deflection amount to correct the deviation. It is also preferable to input coefficients c and d approximated by equations (3) and (4) as the incidence position deviation amount of each primary electron beam. Then, it is preferable for the deflection control circuit 128 to calculate the deviation amount from a polynomial using the coefficients c and d, calculate a deflection amount to correct the deviation amount, and add them together.

[0116] Figure 29 shows an example of performing parallel shift correction on a multi-primary electron beam in Embodiment 2. The incident position shape 13 of the multi-primary electron beam 20 is shifted in parallel to the position of incident position shape 14. This allows for parallel shift correction of the multi-primary electron beam 20.

[0117] Figure 30 shows an example of performing rotational correction of a multi-primary electron beam in Embodiment 2. The incident position shape 13 of the multi-primary electron beam 20 is rotated to the position of incident position shape 14.

[0118] Figure 31 shows an example of performing magnification correction on a multi-primary electron beam in Embodiment 2. The incident position shape 13 of the multi-primary electron beam 20 is magnified to the position of incident position shape 14. For magnification rotation correction, a group of magnification rotation correction lenses consisting of three or more electromagnetic lenses can be provided between the electromagnetic lens 206 and the E×B separator 214 to correct magnification and rotation fluctuations. In addition, a corrector for correcting the incident position of individual beams, having a structure similar to the corrector array 236 installed downstream of the multi-beam generation shaping aperture array 203, can be used.

[0119] As a result, drift correction for the multi-primary electron beam 20 is possible. After drift correction for the multi-primary electron beam 20, the incidence position correction (drift correction) for the multi-secondary electron beam 300 is performed. The contents of each of the steps, the secondary electron beam incidence position displacement measurement step (S120), the determination step (S122), and the secondary electron beam incidence position correction step (S124), are the same as in Embodiment 1.

[0120] As described above, according to Embodiment 2, in addition to correcting the incident position of the multi-secondary electron beam 300, drift correction of the multi-primary electron beam 20 is possible.

[0121] 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 rememory). For example, the position circuit 107, the comparison circuit 108, and the reference image creation circuit 112 may be composed of at least one of the processing circuits described above.

[0122] The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, one or both of the deflectors 225 and 226 may be used instead of the deflector 228 for correction. Also, although the above examples described a case in which the mark 111 is placed near the stripe region 32 after scanning the stripe region 32, the invention is not limited to this. It is also possible that the mark 111 is not placed near the target stripe region 32 at the timing of drift correction. In that case, the stage 105 can be moved to the position of the mark 111 and drift correction can be performed.

[0123] 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.

[0124] Furthermore, all multibeam image acquisition devices and multi-secondary electron beam drift correction methods 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. [Industrial applicability]

[0125] One aspect of the present invention relates to a multibeam image acquisition device and a drift correction method for multiple secondary electron beams. For example, it can be used in a multibeam inspection device that performs pattern inspection using secondary electron images caused by irradiation with multiple primary electron beams. [Explanation of symbols]

[0126] 10 Primary electron beam 11 Incident position 13,14 Injection position shape 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 40 detection elements 42, 43, 44 Electromagnetic lenses 60 Judgment section 61 Incident position deviation measurement processing unit 63 Incident position deviation calculation unit 64. Unit for creating the incident position deviation distribution. 65 Judgment section 66 Correction Processing Unit 70 Judgment section 71 Incident position deviation measurement processing unit 73. Incident position deviation calculation unit 74. Unit for creating the incident position deviation distribution. 75 Judgment section 76 Correction Processing Unit 100 Inspection device 101 circuit board 102 Electron beam column 103 Laboratory 105 Stages 106 Detection Circuit 107 Position circuit 108 Comparison circuit 109 Storage device 110 Control Computer 111 Mark 112 Reference Image Creation Circuit 113 Mark Patterns 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 Multipole Lens Control Circuit 132 E×B Separator Control Circuit 134 Beam adjustment circuit 142 Stage drive mechanism 143, 144, 145, 146, 147, 148, 149 DAC amplifier 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 209 Deflector 212 Bulk deflector 213 Limiting Aperture Substrate 214 E×B separator 216 Mirror 218 Deflector 222 Multi-detector 223 Detector aperture array substrate 224 Multi-stage electromagnetic lens 225,226, 227,228 deflector 229 Multipole Lens 230 Electrostatic Lens 232 Stigma corrector 234 Multipole Lens 236 Multipole Lens Array 300 Multi-Secondary Electron Beam 302 Secondary electron beam 330 Examination Areas 332 chips

Claims

1. A stage on which objects to be irradiated by a multi-primary electron beam are placed, A primary electron optical system that irradiates the target object with the aforementioned multi-primary electron beam, A detector array for detecting the multi-secondary electron beam emitted as a result of the object being irradiated with the multi-primary electron beam, A secondary electron optical system that guides the aforementioned multi-secondary electron beam to the detector array, A deflector that causes the detector to detect a signal waveform caused by the incident position of the secondary electron beam detected by at least one detector in the detector array, which detects the multi-secondary electron beam emitted due to the irradiation of the object with the multi-primary electron beam after a predetermined period has elapsed since the start of irradiation with the multi-primary electron beam, by deflecting the multi-secondary electron beam. A shift amount calculation circuit that calculates the amount of incident position shift using a signal waveform caused by the incident position of at least one detector, A corrector that corrects the incident position of the multi-secondary electron beam onto the detector array so that the amount of deviation is reduced, Equipped with, The deflector causes the detector to detect the signal waveform by scanning the detector with the secondary electron beam detected by the detector. The aforementioned deviation amount calculation circuit uses the signal waveform detected by scanning with the deflector after the predetermined period has elapsed and drift has occurred in the secondary electron beam, to calculate the deviation from the signal waveform obtained when no drift has occurred in the secondary electron beam. A multibeam image acquisition device characterized by the following features.

2. The deflector causes the detectors to detect, by beam deflection of the multi-secondary electron beam, a plurality of signal waveforms, each caused by the incident position of the plurality of secondary electron beams detected by a plurality of detectors in the detector array that detects the multi-secondary electron beams emitted as a result of the irradiation of the target object with the multi-primary electron beam after a predetermined period has elapsed since the start of irradiation of the multi-primary electron beam. The aforementioned displacement calculation circuit calculates the displacement amounts of multiple incident positions on multiple detectors using multiple signal waveforms caused by the incident positions on multiple detectors, The system further includes a distribution generation circuit that generates an incident position shift distribution using the aforementioned multiple incident position shift amounts, The multibeam image acquisition apparatus according to claim 1, characterized in that the corrector corrects the incident position of the multi-secondary electron beam to the detector array using the incident position displacement distribution.

3. The multibeam image acquisition apparatus according to claim 2, characterized in that the corrector has a deflector that parallel shifts the incident position of the multi-secondary electron beam onto the detector array.

4. The multibeam image acquisition apparatus according to claim 2, characterized in that the corrector has a multi-stage lens that corrects the magnification of the distribution of the incident positions of the multi-secondary electron beams to the detector array.

5. The multibeam image acquisition apparatus according to claim 2, characterized in that the corrector has a multi-stage lens that rotates and corrects the position of the distribution of the incident positions of the multi-secondary electron beams to the detector array.

6. The multibeam image acquisition apparatus according to claim 2, characterized in that the corrector has a multipole lens for correcting distortion in the distribution of the incident positions of the multi-secondary electron beams to the detector array.

7. It also features multiple marks arranged along one side of the circuit board being inspected, The multibeam image acquisition apparatus according to claim 1, characterized in that the object includes the plurality of marks.

8. The pattern formation region formed on the substrate to be inspected along one side of the substrate to be inspected is further provided with marks arranged adjacent to the longitudinal ends of all stripe regions, which are divided into a plurality of stripe regions with a predetermined width in a first direction. The multibeam image acquisition apparatus according to claim 1, characterized in that the object includes the mark.

9. The target object is irradiated with a multi-primary electron beam, and the multi-secondary electron beam emitted as a result of the target object being irradiated with the multi-primary electron beam is detected by a detector array. When a predetermined period has elapsed since the start of irradiation with the multi-primary electron beam, at least one detector in the detector array that detects the multi-secondary electron beam emitted as a result of the irradiation of the object with the multi-primary electron beam detects the signal waveform of the secondary electron beam detected by the detector, which is caused by the incident position of the secondary electron beam to the detector, and the beam deflection of the multi-secondary electron beam is used to detect this signal waveform. The amount of deviation in the incident position is calculated using the signal waveform caused by the incident position to at least one of the detectors. The incident position of the multi-secondary electron beam onto the detector array is corrected so that the amount of deviation is reduced. By using a deflector and scanning the detector with the secondary electron beam detected by the detector, the signal waveform is made to be detected by the detector. Using the signal waveform detected by scanning with the deflector after the predetermined period has elapsed and drift has occurred in the secondary electron beam, the deviation from the signal waveform obtained when no drift occurs in the secondary electron beam is calculated. A method for correcting drift in a multi-secondary electron beam, characterized by the features described above.

10. The drift of the aforementioned multi-primary electron beam is corrected, The drift correction method for a multi-secondary electron beam according to claim 9, characterized in that the measurement of the incident position is performed after correcting the drift of the multi-primary electron beam.

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