Multi-electron beam image acquisition apparatus and multi-electron beam image acquisition method

Abstract

A shift in the electron beam position occurs due to a change in the electric field corresponding to the tilt of the substrate to which the desired potential is applied. [Solution] A multi-electron beam image acquisition apparatus according to one aspect of the present invention is characterized by comprising: a primary electron optical system 151 having a first deflector that irradiates a substrate with a multi-primary electron beam; a multi-detector 222 that detects a multi-secondary electron beam separated from the trajectory of the multi-primary electron beam; a secondary electron optical system 152 having a second deflector that projects the separated multi-secondary electron beam onto the multi-detector; and a deflection control circuit 128 that controls the first and second deflectors to correct the positional displacement of the multi-primary electron beam on the substrate caused by the change in the electric field between the primary electron optical system and the substrate to which a desired potential is applied, according to the inclination of the substrate obtained based on the height position of the substrate at multiple positions, using the first deflector, and correcting the positional displacement of the multi-secondary electron beam on the detection surface of the multi-detector using the second deflector.

Description

[Technical Field]

[0001] The present invention relates to a multi-electron beam image acquisition apparatus and a multi-electron beam image acquisition method. For example, it relates to an image acquisition method for a multi-electron beam inspection apparatus that performs pattern inspection using secondary electron images resulting from irradiation with multiple primary electron beams. [Background technology]

[0002] 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 submicron to nanometer. 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, there is a need for highly accurate pattern inspection equipment to inspect defects in ultrafine patterns transferred onto semiconductor wafers.

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

[0004] Furthermore, in devices that acquire images using electron beams, such as inspection equipment, a retarding potential may be applied to the substrate to improve the resolution of the image obtained from the substrate being inspected. The distance between the bottom surface of the optical system housing and the substrate may change due to the running accuracy of the stage, changes in the thickness of the mask, and the deflection of the mask.

[0005] Regarding technologies related to substrate tilt, a technique has been disclosed for correcting errors in the drawing position corresponding to the tilt of the substrate on the stage in a drawing apparatus that does not apply a retarding potential (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 8-274008 [Overview of the project] [Problems that the invention aims to solve]

[0007] In devices that acquire images using an electron beam, such as inspection equipment, applying a retarding potential generates an electric field between the substrate surface and the bottom surface of the optical system body. However, as mentioned above, it has been found that if the distance between the bottom surface of the optical system housing and the substrate changes, that is, if the substrate is tilted relative to the bottom surface of the optical system housing, the electric field changes due to this tilt, and the trajectory of the electron beam changes. This has led to problems such as the irradiation position of the multi-primary electron beam on the substrate shifting. Furthermore, changes in the electric field affect not only the trajectory of the multi-primary electron beam but also the trajectory of the multi-secondary electron beam emitted from the substrate. When the trajectory of the multi-secondary electron beam changes, the position of the multi-secondary electron beam on the multi-detector shifts, leading to problems such as the inability to obtain an image.

[0008] One aspect of the present invention provides an apparatus and method capable of correcting the misalignment of an electron beam caused by changes in the electric field corresponding to the tilt of a substrate to which a desired potential is applied. [Means for solving the problem]

[0009] A multi-electron beam image acquisition apparatus according to one aspect of the present invention is: A stage on which the circuit board is placed, A power supply that applies the desired potential to the circuit board, A measuring mechanism that measures the height position at multiple locations on the circuit board on the stage, A multi-primary electron beam formation mechanism that forms multiple primary electron beams, A primary electron optical system having a first deflector and irradiating a substrate with a multi-primary electron beam, A separator that separates the multi-secondary electron beam emitted as a result of the substrate being irradiated with the multi-primary electron beam from the trajectory of the multi-primary electron beam, A multi-detector that individually detects the multi-secondary electron beams separated from the orbit of the multi-primary electron beam, A secondary electron optical system that projects the multi-secondary electron beam onto a multi-detector, having a second deflector positioned on the trajectory of a multi-secondary electron beam separated from the trajectory of a multi-primary electron beam, A deflection control circuit controls the first and second deflectors to correct the positional displacement of the multi-primary electron beam on the substrate caused by the change in the electric field between the primary electron optical system and the substrate to which a desired potential is applied, in accordance with the inclination of the substrate obtained based on the height position of the substrate at multiple positions, using the first deflector, and to correct the positional displacement of the multi-secondary electron beam on the detection surface of the multi-detector due to the change in the electric field, using the second deflector. It is characterized by having the following features.

[0010] Furthermore, a first position correction map creation unit creates a first position correction map in which a correction amount is defined to correct the positional displacement of the multi-primary electron beam on the substrate according to the inclination of the substrate at each position on the substrate, A second position correction map creation unit that creates a second position correction map in which a correction amount for correcting a positional deviation on the detection surface of the multi-secondary electron beam detector according to the inclination of the substrate at each position on the substrate is defined. Further comprising The deflection control circuit preferably controls the first deflector to correct the positional deviation of the multi-primary electron beam by referring to the first position correction map, and controls the second deflector to correct the positional deviation of the multi-secondary electron beam by referring to the second position correction map.

[0011] It is also preferable to further include an inclination map creation unit that creates an inclination map in which the inclination of the substrate at each position on the substrate is defined.

[0012] Also, a retarding potential is used as the desired potential. The first position correction map and the second position correction map preferably depend on the retarding potential applied to the substrate.

[0013] Also, the first deflector is preferably controlled by a deflection vector obtained by adding a scanning deflection vector for scanning the substrate with the multi-primary electron beam and a deflection vector for correcting the positional deviation of the multi-primary electron beam on the substrate caused by a change in the electric field.

[0014] Also, the second deflector is preferably controlled by a deflection vector obtained by adding a return deflection vector for keeping the position on the detection surface of the multi-secondary electron beam detector that varies when the substrate is scanned with the multi-primary electron beam stationary, and a deflection vector for correcting the positional deviation on the detection surface of the multi-secondary electron beam caused by a change in the electric field.

[0015] A multi-electron beam image acquisition method according to one aspect of the present invention A step of measuring height positions at a plurality of positions on the surface of a substrate placed on a stage and to which a desired potential is applied. A process of irradiating a substrate with a multi-primary electron beam using a primary electron optical system having a first deflector, while correcting the positional displacement of the multi-primary electron beam on the substrate caused by the change in the electric field between the primary electron optical system and the substrate to which a desired potential is applied, according to the tilt of the substrate obtained based on the height position of the substrate at multiple positions, using the first deflector, A process to separate the multi-secondary electron beam emitted as a result of the substrate being irradiated with the multi-primary electron beam from the trajectory of the multi-primary electron beam, A process of individually detecting the multi-secondary electron beams separated from the trajectory of the multi-primary electron beam using a multi-detector, The process involves projecting the multi-secondary electron beam onto a multi-detector using a secondary electron optical system having a second deflector positioned on the trajectory of a multi-secondary electron beam separated from the trajectory of a multi-primary electron beam, while correcting the positional shift of the multi-secondary electron beam on the detection surface of the multi-detector due to changes in the electric field using the second deflector, and It is characterized by having the following features. [Effects of the Invention]

[0016] According to one aspect of the present invention, it is possible to correct the misalignment of the electron beam caused by changes in the electric field corresponding to the tilt of a substrate to which a desired potential is applied. [Brief explanation of the drawing]

[0017] [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 is a diagram illustrating the image acquisition process in Embodiment 1. [Figure 4] This figure shows an example of the electric field and beam trajectory when the substrate in Embodiment 1 is placed horizontally (zero tilt). [Figure 5] This figure shows an example of the electric field and beam trajectory when the substrate is positioned at an angle in Embodiment 1. [Figure 6] This is a block diagram showing an example of the internal configuration of the correction circuit in Embodiment 1. [Figure 7] This is a flowchart illustrating an example of the main steps of the inspection method in Embodiment 1. [Figure 8] This is a top view showing an example of a beam-selection aperture substrate in Embodiment 1. [Figure 9] This figure shows an example of an evaluation substrate in Embodiment 1. [Figure 10] This figure shows an example of the relationship between the x-direction tilt angle and the amount of positional displacement of the primary beam in Embodiment 1, as well as an example of a tilt correction coefficient. [Figure 11] This figure shows an example of the relationship between the y-direction tilt angle and the amount of positional displacement of the primary beam in Embodiment 1, as well as an example of a tilt correction coefficient. [Figure 12] This figure shows an example of the relationship between the x,y direction tilt angle and the amount of positional displacement of the primary beam in Embodiment 1, as well as an example of a tilt correction coefficient. [Figure 13] This figure shows an example of the relationship between the x-direction tilt angle and the amount of displacement of the secondary beam, as well as an example of the tilt correction coefficient, in Embodiment 1. [Figure 14] This figure shows an example of the relationship between the y-direction tilt angle and the amount of displacement of the secondary beam, as well as an example of the tilt correction coefficient, in Embodiment 1. [Figure 15] This figure shows an example of the relationship between the x,y direction tilt angle and the amount of positional displacement of the secondary beam in Embodiment 1, as well as an example of a tilt correction coefficient. [Figure 16] This figure shows an example of a beam trajectory when a substrate to which a retarding potential is applied so that the landing energy in Embodiment 1 is 2.5 keV is tilted by 1 mrad. [Figure 17] This figure shows an example of a beam trajectory when a substrate to which a retarding potential is applied so that the landing energy in Embodiment 1 is 0.5 keV is tilted by 1 mrad. [Figure 18] This figure shows an example of the trajectory of the primary beam due to differences in landing energy in Embodiment 1. [Figure 19] This figure shows an example of the trajectory of the secondary beam due to the difference in landing energy in Embodiment 1. [Figure 20] This figure shows an example of a processing area in Embodiment 1. [Figure 21] This figure shows an example of a height position map in Embodiment 1. [Figure 22] This figure shows an example of an extended height position map in Embodiment 1. [Figure 23] This figure shows an example of a tilt map in the x-direction in Embodiment 1. [Figure 24] This figure shows an example of a y-direction inclination map in Embodiment 1. [Figure 25] This figure shows an example of a primary beam position correction map in Embodiment 1. [Figure 26] This figure shows an example of a secondary beam position correction map in Embodiment 1. [Figure 27] This is a diagram illustrating how to perform corrections in a modified example of Embodiment 1. [Figure 28] This is a diagram showing an example of the configuration within the comparison circuit in Embodiment 1. [Modes for carrying out the invention]

[0018] 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.

[0019] Embodiment 1. Figure 1 is a configuration diagram showing the configuration of a pattern inspection apparatus in Embodiment 1. In Figure 1, the inspection apparatus 100 for inspecting patterns formed on a substrate is an example of a multi-electron beam inspection apparatus. The inspection apparatus 100 includes an image acquisition mechanism 150 and a control system circuit 160. The image acquisition mechanism 150 includes an electron beam column 102 (electron tube), an inspection chamber 103, a detection circuit 106, a chip pattern memory 123, a stage drive mechanism 142, and a laser length measurement system 122. The electron beam column 102 contains an electron gun 201, an electromagnetic lens 202, a shaped aperture array substrate 203, a beam shaping aperture substrate 215, a drive mechanism 217, an electromagnetic lens 205, a single deflector 212, a limiting aperture substrate 213, an electromagnetic lens 206, a deflector 208, an electromagnetic lens 207, a beam separator 214 (an example of a separator), a detector 221, a deflector 218, a deflector 226, an electromagnetic lens 224, and a multi-detector 222.

[0020] The deflector 208, electromagnetic lens 207, and beam separator 214 are positioned on the common trajectory of the multi-primary electron beam 20 and the multi-secondary electron beam 300. In addition, the detector 221, deflector 218, deflector 226, electromagnetic lens 224, and multi-detector 222 are positioned on the trajectory of the multi-secondary electron beam 300, which has been separated from the trajectory of the multi-primary electron beam 20.

[0021] The primary electron optical system 151 is composed of an electron gun 201, an electromagnetic lens 202, a shaped aperture array substrate 203, a beam-selective aperture substrate 215, a drive mechanism 217, an electromagnetic lens 205, a single deflector 212, a limiting aperture substrate 213, an electromagnetic lens 206, a deflector 208, and an electromagnetic lens 207 (objective lens). The secondary electron optical system 152 is composed of an electromagnetic lens 207 (objective lens), a deflector 208, a beam separator 214, a deflector 218, a deflector 226, and an electromagnetic lens 224.

[0022] The primary electron optical system 151 irradiates the substrate 101 with a multi-primary electron beam 20. The secondary electron optical system 152 projects the multi-secondary electron beam 300, separated from the trajectory of the multi-primary electron beam 20, onto the multi-detector 222.

[0023] The group of electronic lenses, such as electromagnetic lenses 202, 205, 206, 207, and 224, may consist of multiple stages of electronic lenses, not just a single stage. Furthermore, these groups of electronic lenses utilize electromagnetic lenses; however, this is not the only option. Electrostatic lenses may be used instead of electromagnetic lenses, or a combination of electromagnetic and electrostatic lenses may be used.

[0024] Furthermore, the deflectors 208 and 226 are not limited to single-stage deflectors, but may be composed of multiple stages.

[0025] A stage 105, movable in at least the X and Y directions, is arranged within the inspection chamber 103. Multiple support rods 210 are individually positioned on the stage 105 so as to be raised and lowered, and the substrate 101 (sample) to be inspected is supported by the multiple support rods 210. In other words, the substrate 101 is placed on the stage 105 with, for example, the pattern-forming surface facing upwards. In the example in Figure 1, for example, it is supported at three points by three support rods 210. The raising and lowering of each support rod 210 is driven by an angle adjustment mechanism (not shown).

[0026] The substrate 101 includes an exposure mask substrate and a semiconductor substrate such as a silicon wafer. When the substrate 101 is a semiconductor substrate, multiple chip patterns (wafer dies) are formed on the semiconductor substrate. When the substrate 101 is an exposure mask substrate, chip patterns are formed on the exposure mask substrate. The chip pattern is composed of multiple graphic patterns. By exposing and transferring the chip pattern formed on the exposure mask substrate onto the semiconductor substrate multiple times, multiple chip patterns (wafer dies) are formed on the semiconductor substrate. The following explanation will mainly focus on the case where the substrate 101 is an exposure mask substrate. Furthermore, a mirror 216 is positioned on the stage 105 to reflect the laser beam used for laser length measurement, which is emitted from the laser length measurement system 122 located outside the inspection room 103.

[0027] A z-sensor 211 is positioned above the inspection chamber 103. The z-sensor 211 includes an irradiator that obliquely incidents laser light onto the substrate, and a sensor that receives reflected light from the substrate 101 and measures the amount of height change from a reference height position at the irradiation position of the substrate 101 using the principle of optical levers. The irradiation position of the laser light is aligned, for example, with the intersection of the substrate surface and the trajectory center axis of the multi-primary electron beam 20.

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

[0029] Furthermore, the detector 221 is configured to be movable both on and off the trajectory of the multi-secondary electron beam 300. The movement of the detector 221 is performed by a drive mechanism (not shown). In the example in Figure 1, the detector 221 is shown to be positioned in front of the deflector 218 (bender), but this is not the only option. For example, it is even more preferable for the detector 221 to be positioned in an intermediate position between the deflector 218 and the trajectory of the multi-secondary electron beam 300 so that it can be moved in and out. The detector 221 is equipped with one detection element that has a sufficiently large detection surface compared to each detection element of the multi-detector 222.

[0030] 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, retarding control circuit 130, separator control circuit 132, correction circuit 134, beam selection aperture control circuit 136, detector control circuit 138, storage device 109 such as a magnetic disk drive, monitor 117, memory 118, and printer 119.

[0031] Furthermore, the deflection control circuit 128 is connected to DAC (digital-to-analog converter) amplifiers 146 and 149. DAC amplifier 146 is connected to deflector 208. DAC amplifier 149 is connected to deflector 226. Furthermore, the deflection control circuit 128 is connected to the voltage control power supply 148. The voltage control power supply 148 is connected to the deflector 218 (bender).

[0032] 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.

[0033] Electromagnetic lenses 202, 205, 206, 207, 224, and beam separator 214 are controlled by lens control circuit 124. The combined 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 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 226 is composed of four or more electrodes and is controlled by deflection control circuit 128 via a DAC amplifier 149 for each electrode.

[0034] The deflector 218 (bender) is configured, for example, as a cylindrical shape bent in an arc shape with multiple electrodes of four or more poles, and each electrode is controlled by a deflection control circuit 128 via a voltage control power supply 148. Alternatively, the deflector 218 may be configured as a flat plate with multiple electrodes of four or more poles, and each electrode may be controlled by a deflection control circuit 128 via a voltage control power supply 148.

[0035] The beam separator 214 has its electric and magnetic fields controlled by the separator control circuit 132. For example, an E×B separator is preferable as the beam separator 214. Alternatively, an electromagnetic prism is also preferable as the beam separator 214. Figure 1 shows an example where an E×B separator is used as the beam separator 214.

[0036] The retarding control circuit 130 applies a desired retarding potential to the substrate 101 to adjust the energy of the multi-primary electron beam 20 irradiated onto the substrate 101. For example, a negative potential is applied to the substrate 101.

[0037] Furthermore, the detector 221 is connected to the detector control circuit 138 outside the electron beam column 102.

[0038] The beam-selection aperture substrate 215 is moved by a drive mechanism 217 in a plane perpendicular to the trajectory center axis of the multi-primary electron beam, under the control of the beam-selection aperture control circuit 136.

[0039] 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.

[0040] The memory device 109 stores the design data (design pattern data) that forms the basis of the patterns formed on the substrate 101.

[0041] Here, Figure 1 shows the configuration necessary to explain Embodiment 1. The inspection device 100 may also have other configurations that are normally necessary.

[0042] Figure 2 is a conceptual diagram showing the configuration of a molded aperture array substrate in Embodiment 1. In Figure 2, the molded aperture array substrate 203 has two-dimensional holes (openings) 22 arranged in m1 horizontal (x-direction) rows × n1 vertical (y-direction) rows (m1, n1 are integers of 2 or more) at a predetermined arrangement pitch in the x and y directions. The example in Figure 2 shows a case where 5 × 5 holes (openings) 22 are formed. Each hole 22 is formed as a circle with the same outer diameter. Alternatively, they may be rectangles of the same dimensions and shape. A portion of the electron beam 200 passes through each of these multiple holes 22 to form a multi-primary electron beam 20. The molded aperture array substrate 203 is an example of a multi-primary electron beam formation mechanism for forming a multi-primary electron beam.

[0043] 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.

[0044] An electron gun 201 (an example of an emission source) emits an electron beam 200 in a divergent direction. The electron beam 200 emitted from the electron gun 201 is refracted in a focusing direction by an electromagnetic lens 202, illuminating the entire molded aperture array substrate 203. As shown in Figure 2, a plurality of holes 22 (openings) are formed in the molded aperture array substrate 203, and the electron beam 200 illuminates the region containing all of the plurality of holes 22. A multi-primary electron beam 20 is formed as each portion of the electron beam 200 irradiated at the location of the plurality of holes 22 passes through each of the plurality of holes 22 in the molded aperture array substrate 203.

[0045] The formed multi-primary electron beam 20 is refracted by electromagnetic lenses 205 and 206, respectively, and proceeds to the beam separator 214, which is positioned at the intermediate image plane (image plane conjugate position) of each beam of the multi-primary electron beam 20, while repeatedly creating intermediate images and crossovers. Furthermore, scattered beams can be shielded by placing a restricting aperture substrate 213 with limited passage holes near the crossover position of the multi-primary electron beam 20. 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.

[0046] When the multi-primary electron beam 20, having passed through the beam separator 214, enters the electromagnetic lens 207, the electromagnetic lens 207 images the multi-primary electron beam 20 onto the substrate 101. In other words, the electromagnetic lens 207 uses the multi-primary electron beam 20 to image the multi-primary electron beam 20 onto the substrate 101. The multi-primary electron beam 20, which has been focused (aligned) onto the surface of the substrate 101 (sample) by the electromagnetic lens 207, is deflected collectively by the 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 irradiates the surface of the substrate 101 with the multi-primary electron beam.

[0047] When the multi-primary electron beam 20 is irradiated onto a desired location on the substrate 101, a bundle of secondary electrons (multi-secondary electron beam 300) containing reflected electrons, corresponding to each beam of the multi-primary electron beam 20, is emitted from the substrate 101 as a result of the irradiation by the multi-primary electron beam 20.

[0048] The multi-secondary electron beam 300 emitted from the substrate 101 passes through the electromagnetic lens 207 and proceeds to the beam separator 214. The beam separator 214 (separator) separates the multi-secondary electron beam 300 from the trajectory of the multi-primary electron beam 20.

[0049] Here, an E×B separator, which is an example of a beam separator 214, has multiple magnetic poles (two or more) using coils and multiple electrodes (two or more). These multiple magnetic poles generate a directional magnetic field. Similarly, the multiple electrodes generate a directional electric field. Specifically, the E×B separator generates electric and magnetic fields in orthogonal directions on a plane perpendicular to the direction in which the central beam of the multi-primary electron beam 20 travels (orbital axis). The electric field exerts a force in the same direction regardless of the direction of electron propagation. In contrast, the magnetic field exerts a force according to Fleming's left-hand rule. Therefore, the direction of the force acting on the electrons can be changed depending on the direction of electron entry. For the multi-beam 20 entering the E×B separator from above, the force due to the electric field and the force due to the magnetic field cancel each other out, and the multi-primary electron beam 20 travels straight downwards. In contrast, the multi-secondary electron beam 300, which enters the E×B separator from below, is subjected to both electric and magnetic field forces acting in the same direction. This causes the multi-secondary electron beam 300 to be statically bent diagonally upward, separating it from the trajectory of the multi-primary electron beam 20.

[0050] The multi-secondary electron beam 300, which has been deflected diagonally upward and separated from the multi-primary electron beam 20, is projected onto the multi-detector 222 by the secondary electron optical system 152. Specifically, the multi-secondary electron beam 300 separated from the multi-primary electron beam 20 proceeds to the deflector 218. The deflector 218 is positioned on the trajectory of the multi-secondary electron beam 300, which has been separated from the trajectory of the multi-primary electron beam 20, and is conjugate to the detection surface of the multi-detector 222. Specifically, the deflector 218 is positioned such that an intermediate position within the deflector 218 (for example, an intermediate position) is conjugate to the detection surface of the multi-detector 222. The multi-secondary electron beam 300 is then further deflected by static deflection by the deflector 218. The multi-secondary electron beam 300, statically deflected by the deflector 218, is projected onto the multi-detector 222 at a position away from the trajectory of the multi-primary electron beam 20, while being refracted in the focusing direction by the electromagnetic lens 224. The multi-detector 222 (multi-secondary electron beam detector) individually detects the refracted and projected multi-secondary electron beam 300.

[0051] Then, each beam of the multi-secondary electron beam 300 collides with the detection element corresponding to each secondary electron beam of the multi-detector 222 on the detection surface of the multi-detector 222, generating electrons and creating secondary electron image data for each pixel. The intensity signal detected by the multi-detector 222 is output to the detection circuit 106. As described above, the multi-detector 222 is composed of multiple detection elements. The signal from each detection element is output to the detection circuit 106 for each detection element.

[0052] Figure 3 is a diagram illustrating the image acquisition process in Embodiment 1. As shown in Figure 3, the inspection area 330 of the substrate 101 is divided into a plurality of stripe areas 32 with a predetermined width in the y direction, for example. The scanning operation by the image acquisition mechanism 150 is performed for each stripe area 32, for example. For example, the scanning operation of the stripe areas 32 is advanced in the x direction relative to the stage 105 while moving the stage 105 in the -x direction. Each stripe area 32 is divided into a plurality of rectangular areas 33 in the longitudinal direction. The movement of the beam to the target rectangular area 33 is performed by simultaneous deflection of the entire multi-primary electron beam 20 by the deflector 208.

[0053] The example in Figure 3 shows, for example, a 5x5 row multi-primary electron beam 20. The irradiation area 34 that can be irradiated with one irradiation of the multi-primary electron beam 20 is defined as (x-direction size obtained by multiplying the design beam pitch in the x-direction of the multi-primary electron beam 20 on the surface of the substrate 10 by the number of beams in the x-direction) × (y-direction size obtained by multiplying the design beam pitch in the y-direction of the multi-primary electron beam 20 on the surface of the substrate 10 by the number of beams in the y-direction). The irradiation area 34 becomes the field of view of the multi-primary electron beam 20. Each primary electron beam 10 constituting the multi-primary electron beam 20 is irradiated into a sub-irradiation area 29 enclosed by the design beam pitch in the x-direction and the design beam pitch in the y-direction where its beam is located, and scans (scans) within the sub-irradiation area 29. Each primary electron beam 10 will be responsible for one of the sub-irradiation areas 29 which is different from each other. Each primary electron beam 10 then irradiates the same location within its assigned sub-irradiation area 29. The deflector 208 deflects the multi-primary electron beam 20 collectively, scanning the surface of the patterned substrate 101 with the multi-primary electron beam 20. In other words, the movement of the primary electron beam 10 within the sub-irradiation area 29 is performed by the collective deflection of the entire multi-primary electron beam 20 by the deflector 208. This operation is repeated, sequentially irradiating one sub-irradiation area 29 with one primary electron beam 10.

[0054] The width of each stripe region 32 is preferably set to be the same as the y-direction size of the irradiation region 34, or narrower by the scan margin. In the example in Figure 3, the case where the irradiation region 34 is the same size as the rectangular region 33 is shown. However, this is not the only case. The irradiation region 34 may be smaller than the rectangular region 33, or it may be larger. Each primary electron beam 10 constituting the multi-primary electron beam 20 is irradiated into the sub-irradiation region 29 where its beam is located, and scans (scans) within the sub-irradiation region 29. Once the scan of one sub-irradiation region 29 is completed, the entire multi-primary electron beam 20 is deflected by the deflector 208 and moves to an adjacent rectangular region 33 within the same stripe region 32. This operation is repeated, sequentially irradiating within the stripe region 32. Once scanning one stripe region 32 is complete, the irradiation region 34 moves to the next stripe region 32 by moving the stage 105 and / or by the deflector 208, which simultaneously deflects the entire multi-primary electron beam 20. In this way, each primary electron beam 10 irradiates a sub-irradiated region 29, and a secondary electron image is acquired. By combining these secondary electron images from each sub-irradiated region 29, a secondary electron image of the rectangular region 33, a secondary electron image of the stripe region 32, or a secondary electron image of the chip 332 is constructed. Furthermore, when actually comparing images, the sub-irradiated region 29 within each rectangular region 33 is further divided into multiple frame regions 30, and the frame images 31, which are the measurement images for each frame region 30, are compared. The example in Figure 3 shows a case where the sub-irradiated region 29 scanned by one primary electron beam 10 is divided into four frame regions 30, for example, by dividing it into two in each of the x and y directions.

[0055] In the example in Figure 3, the first stripe region 32 moves in the x-direction (forward (FWD) direction), the second stripe region 32 moves in the -x direction (backward (BWD) direction), and the third stripe region 32 moves in the x-direction (forward (FWD) direction), showing a case where the scanning direction alternates. However, this is not the only option. All stripe regions 32 may be scanned in the same direction. Also, the scanning direction of the sub-irradiation region 29 is reversed between FWD and BWD. In the example in Figure 3, the line scan repeat direction is shown as an FWD scan, moving from left to right within the sub-irradiation region 29. In BWD, the line scan repeat direction is from right to left within the sub-irradiation region 29. Each line scan is the same in that it moves, for example, from bottom to top (y direction).

[0056] In this case, when the stage 105 moves continuously and irradiates the substrate 101 with the multi-primary electron beam 20, the deflector 208 performs a tracking operation by simultaneous deflection so that the irradiation position of the multi-primary electron beam 20 follows the movement of the stage 105.

[0057] As described above, the image acquisition mechanism 150 proceeds with the scanning operation for each stripe region 32. As described above, the multi-primary electron beam 20 is irradiated, and the multi-secondary electron beam 300 emitted from the substrate 101 due to the irradiation of the multi-primary electron beam 20 forms an intermediate image plane in the deflector 218, is statically deflected by the deflector 218, and is then detected by the multi-detector 222. The detected multi-secondary electron beam 300 may contain backscattered electrons. Alternatively, the backscattered electrons may diverge while moving through the secondary electron optical system and may not reach the multi-detector 222. Then, a secondary electron image is acquired based on the signal of the detected multi-secondary electron beam 300.

[0058] Furthermore, when scanning is performed while the stage 105 is moving continuously, trunking control is performed by the deflector 208 so that the irradiation position of the multi-primary electron beam 20 on the substrate 101 follows the movement of the stage 105.

[0059] Furthermore, scanning the substrate 101 with the multi-primary electron beam 20 causes the emission position of the emitted multi-secondary electron beam 300 to change moment by moment. Similarly, the emission position of the emitted multi-secondary electron beam 300 also changes moment by moment due to trunking control. If left as is, the position of the multi-secondary electron beam 300 on the detection surface of the multi-detector 222 will shift, preventing each secondary electron beam from entering its corresponding detection element. Therefore, the multi-secondary electron beam 300 is dynamically deflected collectively by the deflector 226 to correct the distance shifted by scanning with the multi-primary electron beam 20 and trunking control, thereby fixing the position of the multi-secondary electron beam 300 on the detection surface of the multi-detector 222. When scanning is performed in step-and-repeat operation, trunking control is unnecessary, in which case the multi-secondary electron beam 300 can be dynamically deflected collectively by the deflector 226 to correct the distance shifted by scanning with the multi-primary electron beam 20.

[0060] Figure 4 shows an example of the electric field and beam trajectory when the substrate in Embodiment 1 is placed horizontally (zero tilt). Figure 5 shows an example of the electric field and beam trajectory when the substrate is tilted in Embodiment 1. In the lower graphs of Figures 4 and 5, the vertical axis represents the distance from the substrate, and the horizontal axis represents the distance from the axis. As shown in Figures 4 and 5, a retarding potential (a desired potential) is applied to the substrate 101 from the power supply 9 in the retarding control circuit 130. For example, a negative potential is applied. This adjusts the energy of electrons colliding with the substrate 101, thereby improving the resolution of the image obtained from the substrate 101.

[0061] Here, when a retarding potential is applied to the inspection device 100, an electric field is generated between the surface of the substrate 101 and the underside of the primary electron optical system 151. In the example in Figure 1, the underside of the primary electron optical system 151 corresponds to, for example, the underside of the electromagnetic lens 207. A ground (GND) potential is applied to the underside of the primary electron optical system 151. Therefore, an electric field is generated by the potential difference between the surface of the substrate 101 and the underside of the primary electron optical system 151.

[0062] As shown in Figure 4, when the substrate is placed horizontally (zero tilt), the distance between the surface of the substrate 101 and the bottom surface of the primary electron optical system 151 is uniform. Therefore, the electric field is uniform on the surface of the substrate 101, and as shown in Figure 4, the primary electron beam travels straight down. Similarly, the secondary electron beam travels straight up.

[0063] In contrast, as shown in Figure 5, if the substrate 101 is tilted, the electric field changes due to the tilt. This change in the electric field causes a shift in the trajectory of the primary electron beam near the surface of the substrate 101. Also, the trajectory of the secondary electron beam emitted from the substrate 101 moves in an oblique direction. If the trajectory of the multi-primary electron beam 20 is shifted, it becomes impossible to irradiate the desired position. Furthermore, if the trajectory of the multi-secondary electron beam changes, the position of the multi-secondary electron beam on the multi-detector shifts, and the brightness of the image changes. It may also incident on detection elements other than the desired detection element, resulting in increased crosstalk.

[0064] Furthermore, the change in the electric field depends on the tilt of the substrate 101 and the retarding voltage. In other words, the amount of trajectory deviation (movement) of the multi-primary electron beam 20 depends on the tilt of the substrate 101. Similarly, the amount of trajectory deviation (movement) of the multi-secondary electron beam 300 depends on the tilt of the substrate 101.

[0065] Therefore, in Embodiment 1, a primary beam position correction amount is calculated to correct the trajectory deviation (movement) of the multi-primary electron beam 20, which depends on the tilt amount of the substrate 101, and a secondary beam position correction amount is calculated to correct the trajectory deviation (movement) of the multi-secondary electron beam 300. Then, the irradiation position of the multi-primary electron beam 20 and the irradiation position of the multi-secondary electron beam 300 are corrected using these position correction amounts. A detailed explanation follows below.

[0066] Figure 6 is a block diagram showing an example of the internal configuration of the correction circuit in Embodiment 1. In Figure 6, the correction circuit 134 includes storage devices such as magnetic disk drives 61, 63, 78, 91, 92, 93, a beam selection unit 60, a substrate angle setting unit 62, a height measurement processing unit 64, a substrate tilt calculation unit 68, a primary beam position deviation measurement unit 70, a secondary beam position deviation measurement unit 72, a primary beam tilt correction coefficient calculation unit 74, a secondary beam tilt correction coefficient calculation unit 76, a region division unit 80, a height measurement processing unit 81, a height position map creation unit 82, an extended height position map creation unit 84, a tilt map creation unit 86, a primary beam position correction map creation unit 88, and a secondary beam position correction map creation unit 90.

[0067] The "~ section" in the beam selection section 60, substrate angle setting section 62, height measurement processing section 64, substrate tilt calculation section 68, primary beam position deviation measurement section 70, secondary beam position deviation measurement section 72, primary beam tilt correction coefficient calculation section 74, secondary beam tilt correction coefficient calculation section 76, region division section 80, height measurement processing section 81, height position map creation section 82, extended height position map creation section 84, tilt map creation section 86, primary beam position correction map creation section 88, and secondary beam position correction map creation section 90 includes a processing circuit, which may include an electrical circuit, computer, processor, circuit board, quantum circuit, or semiconductor device. Furthermore, each "~ section" may use a common processing circuit (the same processing circuit), or it may use different processing circuits (separate processing circuits). The necessary input data or calculated results for the beam selection unit 60, substrate angle setting unit 62, height measurement processing unit 64, substrate inclination calculation unit 68, primary beam position deviation measurement unit 70, secondary beam position deviation measurement unit 72, primary beam tilt correction coefficient calculation unit 74, secondary beam tilt correction coefficient calculation unit 76, region division unit 80, height measurement processing unit 81, height position map creation unit 82, extended height position map creation unit 84, tilt map creation unit 86, primary beam position correction map creation unit 88, and secondary beam position correction map creation unit 90 are stored in a memory (not shown) within the correction circuit 134 or in memory 118 each time.

[0068] Figure 7 is a flowchart showing an example of the main steps of the inspection method in Embodiment 1. In Figure 7, the inspection method in Embodiment 1 performs a series of steps: beam selection step (S102), substrate angle setting step (S104), height position measurement step (S106), substrate inclination calculation step (S108), primary beam position displacement measurement step (S110), secondary beam position displacement measurement step (S112), primary beam tilt correction coefficient calculation step (S114), secondary beam tilt correction coefficient calculation step (S116), region division step (S202), height position measurement step (S204), extended height position map creation step (S206), tilt map creation step (S208), primary beam position correction map creation step (S210), secondary beam position correction map creation step (S220), scan (position correction) step (S230), and comparison step (S240).

[0069] The beam selection process (S102), substrate angle setting process (S104), height position measurement process (S106), substrate inclination calculation process (S108), primary beam position deviation measurement process (S110), secondary beam position deviation measurement process (S112), primary beam tilt correction coefficient calculation process (S114), and secondary beam tilt correction coefficient calculation process (S116) are performed in advance using an evaluation substrate.

[0070] First, using the evaluation board, a correction coefficient is determined to calculate the position correction amount that depends on the tilt of the board 101. To do this, the evaluation board is transported to the inspection device 100 and placed on the stage 105. Furthermore, the detector 221 is moved into the orbit of the multi-secondary electron beam 300.

[0071] In the beam selection process (S102), the beam selection unit 60 drives the beam selection aperture substrate 215 with the drive mechanism 217 to select one representative primary electron beam from the multi-primary electron beams 20. For example, the central primary electron beam is selected as the representative primary electron beam. Information on the selected representative primary electron beam is output to the beam selection aperture control circuit 136.

[0072] Figure 8 is a top view showing an example of a beam-selection aperture substrate 215 in Embodiment 1. In Figure 8, the beam-selection aperture substrate 215 has a large aperture 11 that allows the entire multi-primary electron beam 20 to pass through, and a small aperture 13 that allows one primary electron beam to pass through and shields the rest. Under the control of the beam-selection aperture control circuit 136, the drive mechanism 217 moves the beam-selection aperture substrate 215 to a position where only the selected primary electron beam can pass through the small aperture 13.

[0073] As part of the substrate angle setting process (S104), the substrate angle setting unit 62 sets the tilt angle of the evaluation substrate. As will be described later, multiple tilt angles θ are changed sequentially and measured, so here, one of the multiple tilt angles θ is set. The tilt angle is set as the tilt angle θx in the x direction and the tilt angle θy in the y direction. Initially, for example, θx=0 and θy=0 are set. The angle adjustment mechanism (not shown) individually controls the height position of the support rod 210 to roughly adjust the tilt of the substrate 101 so that it matches the set tilt angle. High-precision adjustment is not necessary here; a rough adjustment is sufficient.

[0074] In the height position measurement process (S106), the height measurement processing unit 64 controls the stage control circuit 144 and the z sensor 211 to measure the height position z at any three or more positions (x,y) on the evaluation board. First, the stage control circuit 144 moves the stage 105 so that one of these three or more positions is located at the illumination position of the z sensor 211. Then, the z sensor 211 measures the height position of the board surface at this position. The measured information is output to the correction circuit 134 and stored in the storage device 61. Similarly, the height position is measured at each of the remaining three or more positions, output to the correction circuit 134, and stored in the storage device 61.

[0075] As part of the substrate tilt calculation process (S108), the substrate tilt calculation unit 68 calculates the tilt angles θx and θy of the evaluation substrate using information (coordinates (x,y,z)) of three or more arbitrary points (x,y) on the evaluation substrate and their height position z.

[0076] Figure 9 shows an example of an evaluation substrate in Embodiment 1. In Figure 9, position measurement marks 12 are formed on the evaluation substrate 400. In the example in Figure 9, the marks 12 are shown to be placed at the center of the substrate, but this is not the only case. The marks 12 can be formed at any position. Also, the number of marks 12 is not limited to one; multiple marks 12 may be formed. For example, a cross pattern is preferable as the marks 12.

[0077] As a primary beam misalignment measurement process (S110), the primary beam misalignment measurement unit 70 controls the image acquisition mechanism 150 to measure the amount of misalignment (movement) of the primary electron beam at the current tilt angle of the evaluation substrate 400. Specifically, it operates as follows: The stage 105 is moved so that the mark 12 on the evaluation substrate 400 when the tilt angle is zero is positioned at the irradiation position of the representative primary electron beam when the deflection amount of the deflector 208 is set to zero. In this state, the representative primary electron beam is irradiated toward the evaluation substrate 400, and the region on the evaluation substrate 400 including the mark 12 is scanned with the representative primary electron beam by beam deflection by the deflector 208. A representative secondary electron beam is emitted from the evaluation substrate 400 as a result of scanning with the representative primary electron beam. The representative secondary electron beam is detected by the detector 221. The detection data detected by the detector 221 is output to the detector control circuit 138, and the detector control circuit 138 generates a secondary electron image of the mark 12. The position of the mark center in the obtained secondary electron image is then set as the irradiation position at the given tilt angle. If the tilt angle is θx=0, θy=0, then the position of the mark center is set as the reference position (shift amount=0) of the representative primary electron beam. If the tilt angle is not θx=0, θy=0, then the position of the mark center is shifted from the reference position, so the deflector 208 is used to deflect the mark center to correct the shift in position from the reference irradiation position. The tilt angle and the amount of deflection used to correct the positional shift of the representative primary electron beam are then associated and stored in the memory device 62.

[0078] After measuring the primary beam displacement, the detector 221 is moved outside the trajectory of the multi-secondary electron beam 300.

[0079] As part of the secondary beam misalignment measurement process (S112), the secondary beam misalignment measurement unit 72 controls the image acquisition mechanism 150 to measure the amount of misalignment (movement) of the secondary electron beam at the current tilt angle of the evaluation substrate 400. Specifically, it operates as follows: First, if the misalignment amount of the representative primary electron beam is not zero at the current tilt angle, the deflection amount of the deflector 208 is adjusted so that the misalignment amount becomes zero. In this state, the evaluation substrate is irradiated with the representative primary electron beam without scanning. Irradiation with the representative primary beam causes a representative secondary beam (for example, the central secondary electron beam) to be emitted from the evaluation substrate 400. Next, the representative secondary beam is scanned over the multi-detector 222 by the secondary system deflector 226 over an area larger than the detection elements. This irradiates each detection element with the representative secondary beam. When the representative secondary beam irradiates a detection element, information is sent as a signal to the detection circuit 106. By combining the signals from each detection element, edge information of the detection elements can be obtained, resulting in an image of the multiple detection elements of the multi-detector 222. When the signals from the representative detection element corresponding to the representative secondary beam are imaged, an image of a single detection element is obtained. From the information in these images, the position of the representative secondary beam on the multi-detector 222 can be determined. For example, the image position of the multi-detector 222 when the tilt angle is θx=0, θy=0 is determined. This position is used as a reference. If the tilt angle is not θx=0, θy=0, the position of the representative secondary electron beam on the detection surface of the multi-detector 222 shifts, so the deflector 226 deflects it so that it is detected by the corresponding detection element. Then, the tilt angle and the deflection amount used to correct the positional displacement of the representative secondary electron beam are associated and stored in the memory device 62.

[0080] Then, the process returns to the substrate angle setting step (S104), and the tilt angle of the evaluation substrate 400 is changed sequentially by multiple tilt angles θ. Each time the tilt angle is changed, the steps from the substrate angle setting step (S104) to the secondary beam position displacement measurement step (S112) are repeated. For example, it is preferable to measure by changing the tilt angle at several points in both the x and y directions.

[0081] As a primary beam tilt correction coefficient calculation step (S114), the primary beam tilt correction coefficient calculation unit 74 calculates a tilt correction coefficient of a function to correct the positional displacement of the multi-primary electron beam 20 which depends on the tilt angle of the substrate.

[0082] Figure 10 shows an example of the relationship between the x-direction tilt angle and the primary beam displacement, and an example of the tilt correction coefficient in Embodiment 1. In the example in Figure 10, the x-direction deflection (movement) δx and y-direction deflection (movement) δy are shown to correct the displacement of the representative primary electron beam when the x-direction tilt angle θx of the evaluation substrate 400 is -1, -0.5, 0, 0.5, and 1. The unit of each value is an arbitrary unit [au]. The vertical axis shows the x-direction deflection (movement) δx and the y-direction deflection (movement) δy, and the horizontal axis shows the x-direction tilt angle θx. The approximate function and its coefficients are calculated by fitting the measurement results with, for example, a linear function. The approximations are δx = a × θx + b and δy = c × θx + d. In the example in Figure 10, they can be approximated as follows. δx = 2.0 × θx δy = 0.1 × θx - 2.8 × 10 -18 In such an example, the tilt correction coefficients a and b for the primary beam δx with respect to the x-direction tilt angle θx are, for example, 2.0 and 0, and the tilt correction coefficients c and d for the primary beam δy are, for example, 0.1 and -2.8 × 10 -18 This is the result.

[0083] Figure 11 shows an example of the relationship between the y-direction tilt angle and the primary beam displacement, and an example of the tilt correction coefficient in Embodiment 1. In the example in Figure 11, the x-direction deflection (movement) δx and y-direction deflection (movement) δy that correct the displacement of the representative primary electron beam when the y-direction tilt angle θy of the evaluation substrate 400 is -1, -0.5, 0, 0.5, and 1 are shown. The unit of each value is [au]. The vertical axis shows the x-direction deflection (movement) δx and the y-direction deflection (movement) δy, and the horizontal axis shows the x-direction tilt angle θx. The measurement results are plotted and, for example, the approximate function and its coefficients are calculated by fitting with a linear function. The approximations are δx = a × θx + b and δy = c × θx + d. In the example in Figure 11, they can be approximated as follows. δx = -1.46 × θy + 2.0 × 10 -3 δy = 1.42 × θy - 2.0 × 10 -2 In such an example, the tilt correction coefficients a and b for the primary beam δx with respect to the x-direction tilt angle θx are, for example, -1.46 and 2.0 × 10⁻⁶. -3 Therefore, the tilt correction coefficients c and d for the δy of the primary beam are, for example, 1.42 and -2.0 × 10⁻⁶. -2 This is the result.

[0084] Figure 12 shows an example of the relationship between the x and y tilt angles and the displacement of the primary beam, as well as an example of the tilt correction coefficient in Embodiment 1. In the example in Figure 12, the deflection amount (movement) δx in the x direction and the deflection amount (movement) δy in the y direction are shown for each combination of the x-direction tilt angle θx and the y-direction tilt angle θy. The unit of each value is [au]. The approximate function and its coefficients are calculated by fitting the measurement results with, for example, a two-variable linear function. The approximation is given by δx = a × θx + b × θy + c and δy = d × θx + e × θy + f. In the example shown in Figure 12, the least squares method is used for approximation. As a result, the values ​​shown in Figure 12 can be obtained as the tilt correction coefficients a, b, c for the primary beam δx and d, e, f for the primary beam δy.

[0085] As a secondary beam tilt correction coefficient calculation step (S116), the secondary beam tilt correction coefficient calculation unit 76 calculates a tilt correction coefficient of a function to correct the positional displacement of the multi-primary electron beam 20 which depends on the tilt angle of the substrate.

[0086] Figure 13 shows an example of the relationship between the x-direction tilt angle and the displacement of the secondary beam, and an example of the tilt correction coefficient in Embodiment 1. In the example in Figure 13, the x-direction deflection (movement) δx and y-direction deflection (movement) δy that correct the displacement of the representative secondary electron beam when the x-direction tilt angle θx of the evaluation substrate 400 is -1, -0.5, 0, 0.5, and 1 are shown. The unit of each value is [au]. The vertical axis shows the x-direction deflection (movement) δx and y-direction deflection (movement) δy, and the horizontal axis shows the x-direction tilt angle θx. The approximate function and its coefficients are calculated by fitting the measurement results with, for example, a linear function. The approximations are δx = a × θx + b and δy = c × θx + d. In the example in Figure 13, they can be approximated as follows. δx = 3.0 × θx δy = 0.2 × θx In such an example, the tilt correction coefficients a and b for the secondary beam δx with respect to the x-direction tilt angle θx are, for example, 3.0 and 0, and the tilt correction coefficients c and d for δy are, for example, 0.2 and 0.

[0087] Figure 14 shows an example of the relationship between the y-direction tilt angle and the displacement of the secondary beam, and an example of the tilt correction coefficient in Embodiment 1. In the example in Figure 14, the x-direction deflection (movement) δx and y-direction deflection (movement) δy that correct the displacement of the representative secondary electron beam when the y-direction tilt angle θy of the evaluation substrate 400 is -1, -0.5, 0, 0.5, and 1 are shown. The unit of each value is [au]. The vertical axis shows the x-direction deflection (movement) δx and the y-direction deflection (movement) δy, and the horizontal axis shows the x-direction tilt angle θx. The measurement results are plotted and the approximate function and its coefficients are calculated by fitting, for example, a linear function. The approximations are δx = a × θx + b and δy = c × θx + d. In the example in Figure 14, they can be approximated as follows. δx = -3.0 × 10-1 ×θy - 1.11×10 -11 δy = 2.84×θy In such an example, the tilt correction coefficients a and b of δx of the secondary beam with respect to the tilt angle θx in the x direction are, for example, -3.0×10 -1 , -1.11×10 -11 and the tilt correction coefficients c and d of δy of the secondary beam are, for example, 2.84 and 0.

[0088] FIG. 15 is a diagram showing an example of the relationship between the tilt angles in the x and y directions and the amount of displacement of the secondary beam and an example of the tilt correction coefficient in Embodiment 1. In the example of FIG. 15, the displacement vectors (movement amounts) δx in the x direction and δy in the y direction for each combination of the tilt angle θx in the x direction and the tilt angle θy in the y direction are shown. The unit of each value is [a.u.]. By fitting the measurement results with, for example, a two-variable linear function, an approximation function and its coefficients are calculated. It is approximated by δx = a×θx + b×θy + c and δy = d×θx + e×θy + f. In the example of FIG. 15, it is approximated by the least squares method. As a result, the values shown in FIG. 15 can be obtained as the tilt correction coefficients a, b, c of δx of the secondary beam and the tilt correction coefficients d, e, f of δy of the secondary beam, respectively.

[0089] The tilt correction coefficients calculated as described above are stored in the storage device 78. The amount of displacement of the multi-primary electron beam 20 on the substrate 101 due to the change in the electric field according to the tilt of the substrate 101 shows the same behavior as the amount of displacement of the representative primary electron beam on the evaluation substrate 400. Similarly, the amount of displacement of the multi-secondary electron beam 300 on the detection surface of the multi-detector 222 due to the change in the electric field shows the same behavior as the amount of displacement of the representative secondary electron beam when using the evaluation substrate 400. Therefore, when acquiring an image of the substrate 101 to be inspected, the multi-primary electron beam 20 and the multi-secondary electron beam 300 are corrected using the obtained tilt correction coefficients.

[0090] Figure 16 shows an example of a beam trajectory when a substrate to which a retarding potential is applied so that the landing energy is 2.5 keV is tilted by 1 mrad in Embodiment 1. Figure 17 shows an example of a beam trajectory when a substrate to which a retarding potential is applied so that the landing energy is 0.5 keV is tilted by 1 mrad in Embodiment 1. Figure 18 shows an example of the trajectory of the primary beam due to differences in landing energy in Embodiment 1. Figure 19 shows an example of the trajectory of the secondary beam due to differences in landing energy in Embodiment 1. In Figures 16 and 17, the vertical axis represents the distance from the substrate, and the horizontal axis represents the distance from the axis. In Figures 18 and 19, the vertical axis represents the distance from the axis, and the horizontal axis represents the tilt angle. As shown in Figures 16 to 19, when the landing energy changes, the beam trajectory also changes according to the tilt of the substrate. Since the landing energy depends on the retarding potential, in other words, the amount of displacement of the primary beam and the amount of displacement of the secondary beam depend on the retarding potential applied to the substrate 101.

[0091] The evaluation substrate 400 is removed from the stage 105, and the substrate 101 to be inspected is placed on the stage 105. The position of the beam selection aperture substrate 215 is controlled so that the large aperture 11 is positioned on the trajectory of the multi-primary electron beam 20. The detector 221 is also moved to the outside of the trajectory of the multi-secondary electron beam 300.

[0092] As part of the region division process (S202), the region division unit 80 divides the surface of the substrate 101 into a mesh-like structure of multiple processing regions.

[0093] Figure 20 shows an example of a processing area in Embodiment 1. The surface of the substrate 101 is divided into a plurality of processing areas 15. In the example in Figure 20, for example, it is shown when it is divided into 5 × 5 processing areas 15. To keep the positional variation of the primary electron beam below 1 nm, the following limitations on the tilt angle θ are necessary. 1 x 10 -9 = 4.13 × 10 -6 ·θ Therefore, θ = 4.8 × 10 -7 rad Furthermore, if the accuracy of the z-sensor 211 is set to 10 nm, the size L of the processing area 15 must satisfy the following relationship. (10×10 -9 ) / L≦2.4×10 -7 Therefore, (10×10 -9 ) / (2.4×10 -7 ) = 0.023 ≤ L To achieve sufficient accuracy for the primary electron beam, the required length (L) is greater than 23 mm.

[0094] Next, we will explain the secondary electron beam. Above, for example, 10 mm from the substrate 101, the beam enters the magnetic pole of the electromagnetic lens 207, which acts as the objective lens, creating a drift space where no electric field exists, and the beam travels in a straight line. The linear approximation of the trajectory in the drift space is shifted from the origin on the substrate 101. The position obtained by transferring this shift in the secondary system becomes the position of the beam on the detector. When the substrate 101 is tilted by 1 mrad, the amount of shift on the substrate 101 is 1.47e -6 m. If the secondary system transcription is expanded by, for example, 200 times, then on the multi-detector 222, 1.47 × 10 -6 ×200 = 2.94 × 10 -4 m This is the result. The accuracy of the beam position on the multi-detector 222 depends on the multi-detector 222 and the shape of the beam on the multi-detector 222. For example, it has been found that a 20 μm change in beam position has no effect on a detector diameter of 1 mm. Therefore, 20×10 -6 ≥2.94 × 10 -4 ·θ mrad (20×10 -6 ) / (2.94×10 -4 ) = 0.068 mrad≧θ If the accuracy of the Z sensor 211 is set to 10 nm, the size L of the processing area 15 must satisfy the following relationship. (10×10 -9 ) / L≦0.068×10 -3 rad Therefore, (10×10 -9 ) / (0.068×10 -3 ) = 1.47 × 10 -4 ≤L To achieve sufficient accuracy for the secondary electron beam, L needs to be greater than 147 μm. Therefore, to satisfy both the size requirements for the primary electron beam and the size requirements for the secondary electron beam, a size greater than L=23mm is sufficient. For example, if the size of the substrate 101 is 150 × 150 mm, it is preferable to divide it into, for example, 5 × 5 processing areas 15, with L = 30 mm. Each processing area 15 is divided to a size sufficiently larger than the beam array area (irradiation area 34) of the multi-primary electron beam 20.

[0095] As a height position measurement step (S204), the height measurement processing unit 81 controls the measurement mechanism to measure the height position z at each of the multiple processing areas 15 (x,y) on the substrate 101. The measurement mechanism measures the height position z at the multiple processing areas 15 (positions) on the substrate 101 on the stage 105. The stage control circuit 144 and z sensor 211 are examples of measurement mechanisms. It is preferable that the height position z is measured at, for example, the center position coordinates (x,y) of each processing area 15. Specifically, it operates as follows: First, the stage control circuit 144 moves the stage 105 so that each processing area 15 is positioned at the irradiation position of the z sensor 211. Then, the z sensor 211 measures the height position of the substrate surface at that position. The measured information is output to the correction circuit 134 and stored in the storage device 61.

[0096] Next, the height position map creation unit 82 creates a height position map (z map) in which the height position is defined for each processing area 15.

[0097] Figure 21 shows an example of a height position map in Embodiment 1. In the example in Figure 21, the unit of each value is [au]. In the example in Figure 21, a height position map is shown in which the height position z of a 5x5 processing area 15 is the element.

[0098] As part of the extended height position map creation process (S206), the extended height position map creation unit 84 creates an extended height position map by adding one row of map elements to the outer perimeter of the created height position map. Figure 22 shows an example of an extended height position map in Embodiment 1. In the example in Figure 22, the unit of each value is [au]. In the example in Figure 22, an extended height position map is shown with the height position z of a 7x7 processing area 15 as an element. In the extended area, the same value as the adjacent area on the outer edge of the height position map is defined.

[0099] As part of the tilt map creation process (S208), the tilt map creation unit 86 creates a tilt map in which the tilt θ of the substrate 101 in each processing area 15 on the substrate 101 is defined.

[0100] Figure 23 shows an example of a tilt map in the x-direction in Embodiment 1. Figure 24 shows an example of a y-direction inclination map in Embodiment 1. In the x-direction slope map shown in Figure 23, for each of the 5x5 processing regions 15, the slope angle θx of the processing region 15 is calculated and defined using the height position z of the processing region 15 and the height positions z of the processing regions adjacent to it in the x-direction. For example, the slope angle can be calculated by differentiation. In the y-direction slope map shown in Figure 24, for each of the 5x5 processing regions 15, the slope angle θy of the processing region 15 is calculated and defined using the height position z of the processing region 15 and the height positions z of the adjacent processing regions on both sides in the y direction. For example, the slope angle can be calculated by differentiation.

[0101] As part of the primary beam position correction map creation process (S210), the primary beam position correction map creation unit 88 (first position correction map creation unit) calculates a correction amount (deflection amount: displacement amount) to correct the positional displacement of the multi-primary electron beam on the substrate 101 according to the inclination angle (slope) of the substrate 101 in each processing area 15 on the substrate 101. Then, it creates a primary beam position correction map (first position correction map) in which the calculated correction amount is defined.

[0102] Figure 25 shows an example of a primary beam position correction map in Embodiment 1. In Figure 25, the primary beam position correction map calculates a correction amount δx to correct the x-direction positional deviation of the multi-primary electron beam on the substrate 101, and a correction amount δy to correct the y-direction positional deviation, corresponding to the x-direction tilt angle θx and y-direction tilt angle θy defined in the tilt map. In the example in Figure 25, the correction amount δx is defined in the upper section and the correction amount δy is defined in the lower section for each processing area of ​​the primary beam position correction map.

[0103] The primary beam position correction map creation unit 88 reads the correction coefficients a, b, c, d, e, and f of the primary electron beam from the storage device 78, and uses the x-direction tilt angle θx and y-direction tilt angle θy defined in the tilt map and the approximation function (a two-variable linear equation) defined by the correction coefficients shown in Figure 12 to calculate the correction amounts δx and δy, taking into account the x-direction tilt angle θx and y-direction tilt angle θy. The primary beam position correction map creation unit 88 then creates a primary beam position correction map as shown in Figure 25. The created primary beam position correction map is stored in the storage device 92.

[0104] Alternatively, a primary beam position correction map for the x-direction tilt angle θx and a primary beam position correction map for the y-direction tilt angle θy may be created independently. In this case, the operation would be as follows. The primary beam position correction map creation unit 88 reads a correction coefficient from the storage device 78 to determine the correction amount δx for the x-direction tilt angle θx shown in Figure 10, and calculates the correction amount δx for the x-direction tilt by substituting the x-direction tilt angle θx defined in the tilt map into the approximation function (linear equation) defined by this correction coefficient. Similarly, the primary beam position correction map creation unit 88 reads a correction coefficient from the storage device 78 to determine the correction amount δy for the x-direction tilt angle θx shown in Figure 10, and calculates the correction amount δy for the x-direction tilt by substituting the x-direction tilt angle θx defined in the tilt map into the approximation function (linear equation) defined by this correction coefficient. The primary beam position correction map creation unit 88 then creates a primary beam position correction map that depends on the x-direction tilt (not shown). In this primary beam position correction map that depends on the x-direction tilt, for example, the correction amount δx is defined in the upper section and the correction amount δy is defined in the lower section for each processing area.

[0105] Similarly, the primary beam position correction map creation unit 88 reads a correction coefficient for determining the correction amount δx for the y-direction tilt angle θy from the storage device 78, as shown in Figure 11, and calculates the correction amount δx for the y-direction tilt by substituting the y-direction tilt angle θy defined in the tilt map into the approximation function (linear equation) defined by the correction coefficient. Similarly, as shown in Figure 11, the correction coefficient for determining the correction amount δy for the y-direction tilt angle θy is read from the storage device 78, and calculates the correction amount δy for the y-direction tilt by substituting the y-direction tilt angle θy defined in the tilt map into the approximation function (linear equation) defined by the correction coefficient. The primary beam position correction map creation unit 88 then creates a primary beam position correction map that depends on the y-direction tilt (not shown). In such a primary beam position correction map that depends on the y-direction tilt, for example, the correction amount δx is defined in the upper section and the correction amount δy is defined in the lower section for each processing area.

[0106] As part of the secondary beam position correction map creation process (S220), the secondary beam position correction map creation unit 90 (second position correction map creation unit) calculates a correction amount (deflection amount: displacement amount) to correct the positional displacement of the detection surface of the multi-detector 222 of the multi-secondary electron beam 300 according to the tilt angle (slope) of the substrate 101 in each processing area 15 on the substrate 101. Then it creates a secondary beam position correction map (second position correction map) in which the calculated correction amount is defined.

[0107] Figure 26 shows an example of a secondary beam position correction map in Embodiment 1. In Figure 26, the secondary beam position correction map calculates a correction amount δx to correct the positional displacement of the detection surface of the multi-detector 222 of the multi-secondary electron beam 300 according to the x-direction tilt angle θx and y-direction tilt angle θy defined in the tilt map, and a correction amount δy to correct the positional displacement in the y-direction. In the example in Figure 26, the correction amount δx is defined in the upper section and the correction amount δy is defined in the lower section for each processing area of ​​the secondary beam position correction map.

[0108] The secondary beam position correction map creation unit 90 reads the correction coefficients a, b, c, d, e, and f for the secondary electron beam from the storage device 78, and uses the x-direction tilt angle θx and y-direction tilt angle θy defined in the tilt map and the approximation function (a linear equation with two variables) defined by the correction coefficients shown in Figure 15 to calculate the correction amounts δx and δy, taking into account the x-direction tilt angle θx and y-direction tilt angle θy. Then, the secondary beam position correction map creation unit 90 creates a secondary beam position correction map as shown in Figure 26.

[0109] Alternatively, a secondary beam position correction map for the x-direction tilt angle θx and a secondary beam position correction map for the y-direction tilt angle θy may be created independently. In this case, the operation would be as follows. The secondary beam position correction map creation unit 90 reads a correction coefficient from the storage device 78 to determine the correction amount δx for the x-direction tilt angle θx shown in Figure 13, and calculates the correction amount δx for the x-direction tilt by substituting the x-direction tilt angle θx defined in the tilt map into the approximation function (linear equation) defined by this correction coefficient. Similarly, the unit reads a correction coefficient from the storage device 78 to determine the correction amount δy for the x-direction tilt angle θx shown in Figure 13, and calculates the correction amount δy for the x-direction tilt by substituting the x-direction tilt angle θx defined in the tilt map into the approximation function (linear equation) defined by this correction coefficient. The secondary beam position correction map creation unit 90 then creates a secondary beam position correction map that depends on the x-direction tilt (not shown). In this x-direction tilt-dependent secondary beam position correction map, for example, the correction amount δx is defined in the upper section and the correction amount δy is defined in the lower section for each processing area.

[0110] Similarly, the secondary beam position correction map creation unit 90 reads a correction coefficient for determining the correction amount δx for the y-direction tilt angle θy from the storage device 78, as shown in Figure 14, and calculates the correction amount δx for the y-direction tilt by substituting the y-direction tilt angle θy defined in the tilt map into the approximation function (linear equation) defined by the correction coefficient. Similarly, as shown in Figure 14, for example, the correction coefficient for determining the correction amount δy for the y-direction tilt angle θy is read from the storage device 78, and calculates the correction amount δy for the y-direction tilt by substituting the y-direction tilt angle θy defined in the tilt map into the approximation function (linear equation) defined by the correction coefficient. The secondary beam position correction map creation unit 90 then creates a secondary beam position correction map that depends on the y-direction tilt (not shown). In such a secondary beam position correction map that depends on the y-direction tilt, for example, the correction amount δx is defined in the upper section and the correction amount δy is defined in the lower section for each processing area.

[0111] As shown in Figures 16 to 19, the primary beam displacement and secondary beam displacement depend on the retarding potential applied to the substrate 101. Therefore, the primary beam position correction map and secondary beam position correction map depend on the retarding potential applied to the substrate 101. Consequently, changing the retarding potential will change the values ​​defined in the primary beam position correction map and secondary beam position correction map, even if the tilt angle remains the same.

[0112] As a scanning (position correction) step (S230), the image acquisition mechanism 150 scans the substrate 101 with the multi-primary electron beam 20, detects the multi-secondary electron beam 300 emitted from the substrate 101, and acquires a secondary electron image of the substrate 101. Specifically, it operates as follows: The primary electron optical system 151 irradiates the substrate 101 with the multi-primary electron beam 20 while correcting the positional shift of the multi-primary electron beam 20 on the substrate 101 caused by the change in the electric field between the primary electron optical system 151 and the substrate 101 to which a retarding potential is applied, according to the tilt of the substrate 101 obtained based on the height position of the substrate 101 in multiple processing regions 15, using a deflector 208 (first deflector). Then, the secondary electron optical system 152 projects the multi-secondary electron beam 300 onto the multi-detector 222 while correcting the positional displacement of the multi-secondary electron beam 300 on the detection surface of the multi-detector 222 due to the aforementioned change in the electric field using the deflector 226 (second deflector).

[0113] At that time, the deflection control circuit 128 controls the deflector 208 to correct the positional displacement of the multi-primary electron beam 20 on the substrate caused by the change in the electric field between the primary electron optical system 151 and the substrate 101 to which a retarding potential is applied, based on the tilt of the substrate 101 obtained based on the height position z of the substrate 101 in multiple processing regions 15. Simultaneously, the deflection control circuit 128 controls the deflector 226 to correct the positional displacement of the multi-secondary electron beam 300 on the detection surface of the multi-detector 222 due to the change in the electric field. Specifically, it operates as follows: The deflection control circuit 128 controls the deflector 208 to correct the positional displacement of the multi-primary electron beam 20 by referring to the primary beam position correction map stored in the memory device 92, and controls the deflector 226 to correct the positional displacement of the multi-secondary electron beam 300 by referring to the secondary beam position correction map stored in the memory device 93.

[0114] The deflector 208 is controlled by a deflection amount that is the sum of a deflection amount for scanning the substrate 101 with the multi-primary electron beam 20 and a deflection amount for correcting the positional shift of the multi-primary electron beam 20 on the substrate 101 caused by changes in the electric field.

[0115] Furthermore, the deflector 226 is controlled by a deflection amount which is the sum of a swing-back deflection amount to fix the position of the detection surface of the multi-detector 222 of the multi-secondary electron beam 300, which fluctuates as the multi-primary electron beam 20 scans the substrate 101, and a deflection amount to correct the positional displacement of the detection surface of the multi-secondary electron beam 300 caused by changes in the electric field.

[0116] Here, for example, assuming that the beam is incident perpendicularly without considering changes in the electric field, and assuming a simple positional variation due to the inclination θ of the substrate, the deflection amount DEFp' of the multi-primary electron beam 20 can be defined by the following equation. DEFp′=ap·θx·x+bp·θy·y+Cp In the above equation, the coefficient ap is simply corrected by θx. Similarly, the coefficient bp is simply corrected by θy.

[0117] In contrast, the deflection amount DEFp of the multi-primary electron beam 20 in Embodiment 1 can be defined, for example, by the following equation. DEFp=ap·θx·x+ep·θx·x+bp·θy·y+ep·θy·y+Cp Thus, in Embodiment 1, the correction term ep·θx·x and the correction term ep·θy·y due to the change in the electric field are added together.

[0118] Furthermore, assuming, for example, that the beam is emitted straight up without considering changes in the electric field, and assuming a simple positional variation due to the inclination θ of the substrate, the deflection amount DEFs' of the multi-secondary electron beam 20 can be defined by the following equation. DEFs′=as·θx·x+bs·θy·y+Cs In the above equation, the coefficient as is simply corrected by θx. Similarly, the coefficient bs is simply corrected by θy.

[0119] In contrast, the deflection amount DEFs of the multi-secondary electron beam 300 in Embodiment 1 can be defined, for example, by the following equation. DEFs=as·θx·x+es·θx·x+bs·θy·y+es·θy·y+Cs Thus, in Embodiment 1, the correction term es·θx·x and the correction term es·θy·y due to the change in the electric field are added together.

[0120] Therefore, Embodiment 1 differs in content from a simple positional variation due to the inclination θ of the substrate, which assumes that the primary beam is incident perpendicularly and the secondary beam is emitted straight up, without considering the changes in the electric field described above.

[0121] The image acquisition mechanism 150 proceeds with the scanning operation for each stripe area 32. The processing area 15 is larger than the width of the stripe area 32. Therefore, even if the stripe areas 32 are different, the same correction amount is used when scanning within the same processing area 15.

[0122] Furthermore, the processing area 15 is larger than the beam array area (irradiation area 34) of the multi-primary electron beam 20. Therefore, the amount of positional displacement of each primary electron beam in the multi-primary electron beam 20 due to changes in the electric field will be the same. Thus, it is sufficient to correct the entire multi-primary electron beam 20 at once using the deflector 208. Similarly, the processing area 15 is larger than the beam array area on the substrate of the multi-secondary electron beam 300. Therefore, the amount of positional displacement of each secondary electron beam in the multi-secondary electron beam 300 due to changes in the electric field will be the same. Thus, it is sufficient to correct the entire multi-secondary electron beam 300 at once using the deflector 226.

[0123] Then, the multi-secondary electron beam 300 emitted from the substrate 101 due to irradiation by the multi-primary electron beam 20 is separated from the trajectory of the multi-primary electron beam 20 by static deflection by the beam separator 214, further statically deflected by the deflector 218, and then detected by the multi-detector 222. The detected multi-secondary electron beam 300 may contain backscattered electrons. Alternatively, the backscattered electrons may diverge while moving through the secondary electron optical system and not reach the multi-detector 222. Then, a secondary electron image is acquired based on the signal of the detected multi-secondary electron beam 300. Specifically, the detection data of secondary electrons for each pixel in each sub-irradiation area 29 detected by the multi-detector 222 (measured image data: secondary electron image data: image data under inspection) is output to the detection circuit 106 in the order of measurement. Within the detection circuit 106, the analog detection data is converted to digital data by an A / D converter (not shown) and stored in the chip pattern memory 123. The obtained measurement image data, along with information indicating each position from the position circuit 107, is then transferred to the comparison circuit 108.

[0124] As described above, the positional displacement of the multi-primary electron beam 20 and the multi-secondary electron beam 300 due to the change in the electric field corresponding to the tilt of the substrate 101 are corrected. In the example described above, the case in which the positional displacement of the multi-primary electron beam 20 is corrected with the deflector 208 was explained, but this is not the only case.

[0125] Figure 27 is a diagram illustrating the correction method in a modified example of Embodiment 1. The positional displacement of the multi-secondary electron beam 300 caused by the change in the electric field is corrected by the deflector 226 as described above. On the other hand, no correction is performed by the deflector 208. If left as is, the positional displacement of the multi-primary electron beam 20 may cause each secondary electron beam to be misaligned from the corresponding detection element 221 of the multi-detector 222. Therefore, the deflector 226 is used to correct the positional displacement of the multi-primary electron beam 20 so that it is incident on the corresponding detection element 221. Note that the multi-primary electron beam 20 is not corrected before it is incident on the substrate 101, so it will irradiate the substrate at a misaligned position, but since the entire area is scanned with a shift, scan area omissions can be avoided.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] Next, the reference image creation circuit 112 applies a filter to the design image data of the design pattern, which is the image data of the shape, using a predetermined filter function. This makes it possible to match the design image data, which is the design-side image data with digital image intensity (grayscale values), to the image generation characteristics obtained by irradiation with the multi-primary electron beam 20. The image data of each pixel of the created reference image is output to the comparison circuit 108.

[0130] In the comparison step (S240), the comparison circuit 108 compares the image under inspection with a reference image. Specifically, it operates as follows:

[0131] Figure 28 is a diagram showing an example of the configuration within the comparison circuit in Embodiment 1. In Figure 28, 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.

[0132] The measurement image data (stripe image) transferred to the comparison circuit 108 is stored in the storage device 50. The reference image data transferred to the comparison circuit 108 is stored in the storage device 52.

[0133] The frame image creation unit 54 then creates frame images 31 for each of the multiple frame regions 30 obtained by further dividing the stripe image data acquired by the scanning operation of each primary electron beam 10. The frame regions 30 are then used as unit regions of the image under inspection. Preferably, each frame region 30 is configured so that its margin regions overlap with each other to prevent any gaps in the image. The created frame images 31 are stored in the storage device 56.

[0134] 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.

[0135] The comparison unit 58 then compares at least a portion of the acquired secondary electron image with a predetermined image. Here, frame images obtained by further dividing the image of the sub-irradiation region 29 acquired for each beam are used. The comparison unit 58 then compares the frame image 31 and the reference image pixel by pixel. The comparison unit 58 compares the two pixel by pixel according to predetermined judgment conditions and determines the presence or absence of defects, such as shape defects. For example, if the difference in grayscale value for each pixel is greater than the judgment threshold Th, it is determined to be a defect. The comparison result is then output. The comparison result can be output to the storage device 109 or memory 118, or output from the printer 119.

[0136] As described above, according to Embodiment 1, it is possible to correct the positional shift of the electron beam caused by the change in the electric field corresponding to the tilt of the substrate to which the desired potential is applied.

[0137] 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.

[0138] The embodiments have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In the examples described above, a configuration for correcting positional displacement caused by changes in the electric field that occur when, for example, a negative retarding potential is applied to the substrate 101 has been described, but the invention is not limited to this. An electric field can be generated on the substrate 101 by applying some kind of potential to the substrate 101. Therefore, the embodiments described above can be applied to correct positional displacement caused by changes in the electric field corresponding to the tilt of the substrate 101, as long as an electric field is generated on the substrate.

[0139] 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.

[0140] Furthermore, all multi-electron beam image acquisition apparatuses and multi-electron beam image acquisition methods that incorporate elements of the present invention and can be appropriately modified in design by those skilled in the art are included within the scope of the present invention. [Explanation of Symbols]

[0141] 9 Power supply 10 Primary electron beam 11 Large opening 12 marks 13 Small opening 15 Processing area 20. Multi-primary electron beam 22 holes 29 Sub-irradiation area 30 frame area 31 frame images 32 Stripe Area 33 Rectangular area 34 Irradiation area 50,52,56 storage device 54 Frame Image Creation Section 57 Alignment section 58 Comparison Section 61,63,78,91,92,93 Storage device 60 Beam selection section 62 Circuit board angle setting section 64 Height Measurement Processing Unit 68. Substrate tilt calculation unit 70 Primary beam misalignment measurement unit 72 Secondary beam misalignment measurement unit 74 Primary beam tilt correction coefficient calculation unit 76 Secondary beam tilt correction coefficient calculation unit 80 Area division part 81 Height measurement processing unit 82 Height Position Map Creation Section 84 Extended Height Position Map Creation Unit 86. Slope Map Creation Section 88 Primary Beam Position Correction Map Creation Section 90 Secondary beam position correction map creation section 100 Inspection device 101 circuit board 102 Electron beam column 103 Laboratory 106 Detection Circuit 107 Position circuit 108 Comparison circuit 109 Storage device 110 Control Computer 112 Reference Image Creation Circuit 114 Stage Control Circuit 117 Monitors 118 memory 119 Printer 120 bus 122 Laser length measuring system 123 Chip Pattern Memory 124 Lens control circuit 126 Blanking control circuit 128 Deflection control circuit 130 Retarding control circuit 132 Separator control circuit 134 Correction Circuit 136 Beam Selection Aperture Control Circuit 138 Detector control circuit 142 Stage drive mechanism 148 Voltage-controlled power supply 150 Image acquisition mechanism 151 Primary electron optical system 152 Secondary electron optical system 160 Control System Circuits 200 electron beam 201 Electron Gun 202, 205, 207 Electromagnetic lenses 203,204 Molded aperture array substrates 208 Deflector 210 Support rod 211 z sensor 212 Bulk deflector 213 Limiting Aperture Substrate 214 Beam Separator 215 Beam-selective aperture substrate 216 Mirror 217 Drive mechanism 218 Deflector 221 Detectors 222 Multi-detector 224 Electromagnetic Lens 226 Deflector 300 Multi-Secondary Electron Beam 400 evaluation boards

Claims

1. A stage on which the circuit board is placed, A power supply for applying a desired potential to the aforementioned substrate, A measuring mechanism for measuring the height positions at multiple locations on the substrate on the stage, A multi-primary electron beam formation mechanism that forms multiple primary electron beams, A primary electron optical system having a first deflector and irradiating the substrate with the multi-primary electron beam, A separator for separating the multi-secondary electron beam emitted as a result of the substrate being irradiated with the multi-primary electron beam from the trajectory of the multi-primary electron beam, A multi-detector for individually detecting the multi-secondary electron beams separated from the orbit of the multi-primary electron beam, A secondary electron optical system that projects the multi-secondary electron beam onto the multi-detector, having a second deflector positioned on the trajectory of the multi-secondary electron beam separated from the trajectory of the multi-primary electron beam, A deflection control circuit controls the first and second deflectors to correct the positional displacement of the multi-primary electron beam on the substrate caused by the change in the electric field between the primary electron optical system and the substrate to which the desired potential is applied, in accordance with the tilt of the substrate obtained based on the height position of the substrate at the aforementioned plurality of positions, using the first deflector, and to correct the positional displacement of the multi-secondary electron beam on the detection surface of the multi-detector due to the change in the electric field using the second deflector. A multi-electron beam image acquisition apparatus characterized by being equipped with the following features.

2. A first position correction map creation unit creates a first position correction map in which a correction amount is defined for correcting the positional displacement of the multi-primary electron beam on the substrate according to the inclination of the substrate at each position on the substrate, A second position correction map creation unit creates a second position correction map in which a correction amount is defined for correcting the positional misalignment of the multi secondary electron beam on the detection surface of the multi detector according to the inclination of the substrate at each position on the substrate, Furthermore, The multi-electron beam image acquisition apparatus according to claim 1, characterized in that the deflection control circuit controls the first deflector to correct the positional misalignment of the multi-primary electron beam by referring to the first position correction map, and controls the second deflector to correct the positional misalignment of the multi-secondary electron beam by referring to the second position correction map.

3. The multi-electron beam image acquisition apparatus according to claim 1 or 2, further comprising a tilt map creation unit that creates a tilt map in which the tilt of the substrate at each position on the substrate is defined.

4. The retarding potential is used as the desired potential. The multi-electron beam image acquisition apparatus according to claim 1 or 2, characterized in that the first position correction map and the second position correction map depend on the retarding potential applied to the substrate.

5. The multi-electron beam image acquisition apparatus according to claim 1 or 2, characterized in that the first deflector is controlled by a deflection amount obtained by adding a deflection amount for scanning the substrate with the multi-primary electron beam and a deflection amount for correcting the positional displacement of the multi-primary electron beam on the substrate caused by the change in the electric field.

6. The multi-electron beam image acquisition apparatus according to claim 1 or 2, characterized in that the second deflector is controlled by a deflection amount obtained by adding a deflection amount for fixing the position of the multi-secondary electron beam, which fluctuates by scanning the substrate with the multi-primary electron beam, on the detection surface of the multi-detector, and a deflection amount for correcting the positional displacement of the multi-secondary electron beam on the detection surface caused by the change in the electric field.

7. A process of measuring the height positions at multiple locations on the surface of a substrate placed on a stage to which a desired potential is applied, A step of irradiating the substrate with a multi-primary electron beam using a primary electron optical system having a first deflector, while correcting the positional displacement of the multi-primary electron beam on the substrate caused by the change in the electric field between the primary electron optical system and the substrate to which the desired potential is applied, according to the tilt of the substrate obtained based on the height position of the substrate at the plurality of positions, using the first deflector, A step of separating the multi-secondary electron beam emitted as a result of the substrate being irradiated with the multi-primary electron beam from the trajectory of the multi-primary electron beam, A step of individually detecting the multi-secondary electron beams separated from the trajectory of the multi-primary electron beam using a multi-detector, A secondary electron optical system having a second deflector positioned on the trajectory of the multi-secondary electron beam separated from the trajectory of the multi-primary electron beam, projects the multi-secondary electron beam onto the multi-detector while correcting the positional displacement of the multi-secondary electron beam on the detection surface of the multi-detector due to the change in the electric field using the second deflector, A multi-electron beam image acquisition method characterized by comprising the following features.

Images