Electromagnetic lens, scanning electron microscope, and multi electron beam inspection device

Abstract

PURPOSE: To provide an electromagnetic lens and a device, capable of suppressing a discharge between an objective lens and a sample.CONSTITUTION: An electromagnetic lens 207 (an objective lens) of an embodiment of the present invention, comprises: a coil 40; a yoke 42 that is formed by a magnetic body, includes an upper wall on an upstream side of a progressing direction of a primary electron beam to be passed, an outer peripheral wall, an inner peripheral wall, and a lower wall in which a gap is formed to a downstream side of a progressing direction of a primary electron beam or an oblique wall in which the gap is formed to the downstream side of the progressing direction of the primary electron beam, is constructed so that the primary electron beam passes a space surrounded by the inner peripheral wall, and surrounds the coil by the upper wall, the outer peripheral wall, the inner peripheral wall, the lower wall, or the oblique wall; and a cover 44 that contacts and covers an end surface containing an inner peripheral side corner part of a downstream end of the progressing direction of the primary electron beam of the yoke, is formed by a non-magnetic conductor, and in which a corner part is formed to a curvature surface.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an electromagnetic lens, a scanning electron microscope, and a multi-electron beam inspection apparatus. For example, it relates to an electromagnetic lens mounted on a multi-beam inspection apparatus for pattern inspection using a secondary electron image caused by irradiation with a multi-primary electron beam.

Background Art

[0002] In recent years, with the increasing integration and large capacity of large-scale integrated circuits (LSIs), the circuit line width required for semiconductor elements has been becoming increasingly narrow. And for the manufacture of LSIs that require a great deal of manufacturing cost, improvement in yield is essential. However, as represented by 1-gigabit-class DRAMs (random access memories), the patterns constituting LSIs are on the order of sub-microns to nanometers. In recent years, with the miniaturization of LSI pattern dimensions formed on a semiconductor wafer, the dimensions that must be detected as pattern defects have also become extremely small. Therefore, in order to inspect defects in ultra-fine patterns transferred onto a semiconductor wafer, it is necessary to capture highly accurate images.

[0003] In an inspection apparatus, for example, after focusing a multi-primary electron beam using an electron beam on an inspection target substrate, the inspection target substrate is scanned with the multi-primary electron beam, and a multi-secondary electron beam emitted from the inspection target substrate is separated from the orbit of the multi-primary electron beam. Then, the separated multi-secondary electron beam is guided to a detector. Then, the multi-secondary electron beam is detected by the detector to capture a pattern image.

[0004] Here, increasing the acceleration voltage of the inspection apparatus can reduce the aberration caused by the lens barrel. However, when irradiating the sample with the acceleration voltage as it is, the scattering region of the primary electron beam becomes large and the resolution deteriorates. Therefore, a retarding method is used in which a negative potential is applied to the surface of the substrate to be inspected to attenuate the primary electron beam immediately before the sample, reducing the aberration and performing high-resolution inspection. The retarding method allows the beam to pass through the lens barrel at high acceleration to suppress the influence of aberration, and by applying a negative voltage to the sample, it is decelerated immediately before reaching the sample, reducing the scattering region of the primary electron beam and improving the resolution. At this time, while an electric field is generated between the objective lens and the substrate to be inspected, if the distance between the lower surface of the objective lens and the surface of the substrate to be inspected is reduced, there is a problem that discharge due to electric field concentration may occur at the corner of the yoke end of the objective lens.

[0005] Here, a technique of disposing a control electrode plate between the objective lens and the sample to avoid discharge is disclosed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] Therefore, one aspect of the present invention provides an electromagnetic lens and an apparatus capable of suppressing discharge between an objective lens and a sample.

Means for Solving the Problems

[0008] An electromagnetic lens according to one aspect of the present invention is a coil, It is formed of a magnetic material and has an upper wall, an outer peripheral wall, and an inner peripheral wall on the upstream side in the traveling direction of the primary electron beam passing therethrough, and a lower wall having a gap formed on the downstream side in the traveling direction of the primary electron beam or an inclined wall forming a gap on the downstream side in the traveling direction of the primary electron beam. The primary electron beam is configured to pass through the space surrounded by the inner peripheral wall, and a yoke that surrounds the coil with the upper wall, the outer peripheral wall, the inner peripheral wall, and the lower wall or the inclined wall, A cover formed of a non-magnetic conductor that contacts and covers an end surface including an inner peripheral side corner portion at the downstream end of the yoke in the traveling direction of the primary electron beam, and having a corner portion formed as a curved surface, characterized by comprising.

[0009] Further, on the downstream side in the traveling direction of the primary electron beam of the electron lens, a substrate that is irradiated with the primary electron beam and to which a retarding potential is applied is disposed, It is preferable that the radius of curvature of the curved surface of the corner portion of the cover is set such that the electric field strength at the corner portion is equal to or less than a threshold value in a state where a ground potential is applied to the yoke and a retarding potential is applied to the substrate.

[0010] Further, the cover A first cover member that covers an end surface including an inner peripheral side corner portion at the downstream end of the inner wall in the traveling direction of the primary electron beam, A second cover member that covers an end surface including an inner peripheral side corner portion at the downstream end of the lower wall or the inclined wall in the traveling direction of the primary electron beam, is preferably provided.

[0011] Further, the cover also covers a part of the inner peripheral surface continuing from the downstream end surface of the yoke in the traveling direction of the multi-electron beam, It is preferable that a first thickness covering a part of the inner peripheral surface is larger than a second thickness covering the downstream end surface.

[0012] A scanning electron microscope according to one aspect of the present invention A coil, It is formed of a magnetic material and has an upper wall, an outer peripheral wall, and an inner peripheral wall on the upstream side in the traveling direction of the primary electron beam passing therethrough, and a lower wall having a gap formed on the downstream side in the traveling direction of the primary electron beam or an inclined wall forming a gap on the downstream side in the traveling direction of the primary electron beam. The primary electron beam is configured to pass through the space surrounded by the inner peripheral wall. A yoke surrounds the coil with the upper wall, the outer peripheral wall, the inner peripheral wall, and the lower wall or the inclined wall. A cover formed of a non-magnetic conductor that contacts and covers an end surface including an inner peripheral side corner portion at the downstream end of the yoke in the traveling direction of the primary electron beam, and having a corner portion formed as a curved surface. An electromagnetic lens having the same. A stage on which a sample that receives irradiation of the primary electron beam that has passed through the electromagnetic lens is placed. A detector that detects a secondary electron beam emitted from the sample. It is characterized by comprising the same.

[0013] A multi-electron beam inspection apparatus according to an aspect of the present invention. A coil. It is formed of a magnetic material and has an upper wall, an outer peripheral wall, and an inner peripheral wall on the upstream side in the traveling direction of the primary electron beam passing therethrough, and a lower wall having a gap formed on the downstream side in the traveling direction of the primary electron beam or an inclined wall forming a gap on the downstream side in the traveling direction of the primary electron beam. The primary electron beam is configured to pass through the space surrounded by the inner peripheral wall. A yoke surrounds the coil with the upper wall, the outer peripheral wall, the inner peripheral wall, and the lower wall or the inclined wall. A cover formed of a non-magnetic conductor that contacts and covers an end surface including an inner peripheral side corner portion at the downstream end of the yoke in the traveling direction of the primary electron beam, and having a corner portion formed as a curved surface. An electromagnetic lens having the same. A stage on which a sample that receives irradiation of the primary electron beam that has passed through the electromagnetic lens is placed. A detector that detects a secondary electron beam emitted from the sample. It is characterized by comprising the same.

Advantages of the Invention

[0014] According to one aspect of the present invention, discharge between the objective lens and the sample can be suppressed.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Modes for Carrying Out the Invention

[0016] Hereinafter, in the embodiments, as an example of an electron beam, a multi-electron beam will be used for explanation. In other words, as an example of a primary electron beam, a multi-primary electron beam will be used for explanation. As an example of a secondary electron beam, a multi-secondary electron beam will be used for explanation. However, the electron beam is not limited to a multi-electron beam, and may be a single electron beam with one beam number. Further, as an example of an electron beam irradiation device, an electron beam inspection device will be described. However, the electron beam irradiation device is not limited to an inspection device, and may be, for example, a scanning electron microscope or an electron beam image acquisition device.

[0017] Embodiment 1. FIG. 1 is a configuration diagram showing the configuration of the pattern inspection apparatus according to Embodiment 1. In FIG. 1, an inspection apparatus 100 for inspecting a pattern formed on a substrate is an example of a multi-electron beam inspection apparatus. The inspection apparatus 100 is an example of an electron beam irradiation apparatus. The inspection apparatus 100 is an example of a scanning electron microscope or an electron beam image acquisition apparatus. The inspection apparatus 100 includes an image acquisition mechanism 150 and a control system circuit 160 (control unit). The image acquisition mechanism 150 includes an electron beam column 102 (electron lens barrel), an inspection chamber 103, a detection circuit 106, a chip pattern memory 123, a stage drive mechanism 142, and a laser length measurement system 122. Inside the electron beam column 102, an electron gun 201, an electromagnetic lens 202, an electromagnetic lens 205, a blanker deflector 212, a limiting aperture substrate 213, an electromagnetic lens 206, an E×B separator 214 (separator), an electromagnetic lens 207 (objective lens), deflectors 208, 209, deflector 218, deflector 225, an electromagnetic lens 224, and a multi-detector 222 are arranged. During the operation of the inspection apparatus 100, the inside of the electron beam column 102 and the inside of the inspection chamber 103 are evacuated by a vacuum pump (not shown) or the like and adjusted to a vacuum state.

[0018] The electron gun 201, the electron gun 201, the electromagnetic lens 202, the electromagnetic lens 205, the blanker deflector 212, the limiting aperture substrate 213, the electromagnetic lens 206, the E×B separator 214 (separator), the electromagnetic lens 207, and the deflectors 208, 209 constitute a primary electron optical system 151 (illumination optical system). Also, the electromagnetic lens 207, the deflectors 208, 209, the E×B separator 214, the deflector 218, the deflector 225, and the electromagnetic lens 224 constitute a secondary electron optical system 152 (detection optical system).

[0019] In the example of FIG. 1, although the illustration of the yokes surrounding the coils for the electromagnetic lenses 202, 205, 206, 224 other than the electromagnetic lens 207 and the E×B separator 214 is omitted, it goes without saying that yokes are arranged for all of them. In these electromagnetic lenses, the shape of the yoke may be different for each electromagnetic lens, or the shapes of the yokes of two or more electromagnetic lenses may be the same.

[0020] The multi-detector 222 has a plurality of detection elements arranged in an array (lattice) shape.

[0021] In the inspection chamber 103, at least a stage 105 movable in the XY directions is arranged. On the stage 105, a substrate 101 (sample) to be inspected is arranged. The substrate 101 includes an exposure mask substrate and a semiconductor substrate such as a silicon wafer. When the substrate 101 is a semiconductor substrate, a plurality of chip patterns (wafer dice) are formed on the semiconductor substrate. When the substrate 101 is an exposure mask substrate, a chip pattern is formed on the exposure mask substrate. The chip pattern is composed of a plurality of graphic patterns. By exposing and transferring the chip pattern formed on such an exposure mask substrate onto the semiconductor substrate a plurality of times, a plurality of chip patterns (wafer dice) are formed on the semiconductor substrate. The substrate 101 is arranged on the stage 105, for example, with the pattern formation surface facing upward. Also, on the stage 105, a mirror 216 that reflects the laser light for laser length measurement irradiated from a laser length measurement system 122 arranged outside the inspection chamber 103 is arranged. Also, on the stage 105, a mark 111 arranged at the same height position as the surface of the substrate 101 is arranged. For example, a cross pattern is formed on the mark 111.

[0022] Also, the multi-detector 222 is connected to a detection circuit 106 outside the electron beam column 102. The detection circuit 106 is connected to a chip pattern memory 123.

[0023] In the control system circuit 160, a control computer 110 that controls the entire inspection apparatus 100 is connected via a bus 120 to a position circuit 107, a comparison circuit 108, a reference image creation circuit 112, a stage control circuit 114, a lens control circuit 124, a blanking control circuit 126, a deflection control circuit 128, a retardation control circuit 130, an E×B separator control circuit 132, a storage device 109 such as a magnetic disk device, a monitor 117, a memory 118, and a printer 119. Also, the deflection control circuit 128 is connected to DAC (digital-to-analog conversion) amplifiers 144, 146, 147, and a DC power supply 148. The DAC amplifier 146 is connected to the deflector 208, the DAC amplifier 144 is connected to the deflector 209. The DC power supply 148 is connected to the deflector 218. The DAC amplifier 147 is connected to the deflector 225.

[0024] Also, the chip pattern memory 123 is connected to the comparison circuit 108. Also, the stage 105 is driven by a drive mechanism 142 under the control of the stage control circuit 114. In the drive mechanism 142, for example, a drive system such as a three-axis (X-Y-θ) motor that drives in the X direction, Y direction, and θ direction in the stage coordinate system is configured, and the stage 105 can move in the XYθ directions. These X motor, Y motor, and θ motor (not shown) can use, for example, a stepping motor. The stage 105 can move in the horizontal direction and the rotational direction by the motors of each of the XYθ axes. And the moving position of the stage 105 is measured by a laser length measurement system 122 and supplied to the position circuit 107. The laser length measurement system 122 measures the length of the position of the stage 105 based on the principle of laser interference by receiving the reflected light from the mirror 216. The stage coordinate system is set, for example, with the X direction, Y direction, and θ direction of the primary coordinate system with respect to the plane orthogonal to the optical axis of the multi-primary electron beam 20.

[0025] The electromagnetic lens 202, electromagnetic lens 205, electromagnetic lens 206, electromagnetic lens 207, and electromagnetic lens 224 are controlled by the lens control circuit 124.

[0026] In addition, the batch deflector 212 is composed of two or more electrodes and is controlled by the blanking control circuit 126 via a DAC amplifier (not shown) for each electrode. The deflector 209 is composed of four or more electrodes and is controlled by the deflection control circuit 128 via the DAC amplifier 144 for each electrode. The deflector 208 is composed of four or more electrodes and is controlled by the deflection control circuit 128 via the DAC amplifier 146 for each electrode. Further, the deflector 225 is composed of four or more electrodes and is controlled by the deflection control circuit 128 via the DAC amplifier 147 for each electrode.

[0027] The deflector 218 (vendor) is configured, for example, in a cylindrical shape curved in an arc by a plurality of four or more electrodes and is controlled by the deflection control circuit 128 via the DC power supply 148 for each electrode. Alternatively, the deflector 218 may be configured by a plurality of four or more flat electrodes and may be configured to be controlled by the deflection control circuit 128 via the DC power supply 148 for each electrode.

[0028] The E×B separator 214 is controlled by the E×B separator control circuit 132.

[0029] The retarding control circuit 130 applies a retarding potential to the surface of the substrate 101 so that the multi-primary electron beam 20 can obtain a desired landing energy on the surface of the substrate 101. Generally, a negative potential is applied as the retarding potential.

[0030] A high-voltage power supply circuit (not shown) is connected to the electron gun 201. With the application of an acceleration voltage from the high-voltage power supply circuit between a filament (not shown) and a extraction electrode in the electron gun 201, along with the application of a voltage to a predetermined extraction electrode and the heating of a cathode at a predetermined temperature, the electron group emitted from the cathode is accelerated and emitted as the electron beam 200.

[0031] Here, in FIG. 1, the configurations necessary for explaining the first embodiment are described. The inspection apparatus 100 may usually be provided with other necessary configurations.

[0032] FIG. 2 is a top view showing an example of the configuration of the shaping aperture array substrate in Embodiment 1. In FIG. 2, on the shaping aperture array substrate 203, a two-dimensional horizontal (x-direction) m 1 columns × vertical (y-direction) n 1 stages (m 1 , n 1 are integers of 2 or more) of holes (openings) 22 are formed at a predetermined array pitch in the x and y directions. In the example of FIG. 2, for example, the case where 23×23 holes (openings) 22 are formed is shown. Each of the holes 22 is formed in a circular shape with the same dimensional shape. Alternatively, as shown in FIG. 2, they may all be rectangles with the same dimensional shape. When a part of the electron beam 200 passes through each of these plurality of holes 22, a multi-primary electron beam 20 is formed. The shaping aperture array substrate 203 is an example of a multi-beam forming mechanism for forming the multi-primary electron beam 20.

[0033] The electron beam 200 emitted from the electron gun 201 (emission source) is refracted by the electromagnetic lens 202 and illuminates the entire shaping aperture array substrate 203. As shown in FIG. 2, a plurality of holes 22 (openings) are formed in the shaping aperture array substrate 203, and the electron beam 200 illuminates the region including all the plurality of holes 22. Each part of the electron beam 200 irradiated at the positions of the plurality of holes 22 passes through the plurality of holes 22 of the shaping aperture array substrate 203 respectively, thereby forming a multi-primary electron beam 20.

[0034] The formed multi-primary electron beam 20 is refracted by the electromagnetic lens 205 and the electromagnetic lens 206 respectively, and while repeating intermediate images and crossovers, passes through the E×B separator 214 arranged on the intermediate image plane of each beam of the multi-primary electron beam 20 and proceeds to the electromagnetic lens 207 (objective lens).

[0035] When the multi-primary electron beam 20 is incident on the electromagnetic lens 207 (objective lens), the electromagnetic lens 207 focuses the multi-primary electron beam 20 on the substrate 101. The multi-primary electron beam 20 focused (brought into focus) on the surface of the substrate 101 (sample) by the objective lens 207 is collectively deflected by the deflector 208 and the deflector 209, and is irradiated onto the respective irradiation positions of each beam on the substrate 101. When the entire multi-primary electron beam 20 is collectively deflected by the collective blanking deflector 212, the position deviates from the center hole of the limiting aperture substrate 213, and the entire multi-primary electron beam 20 is shielded by the limiting aperture substrate 213. On the other hand, the multi-primary electron beam 20 that has not been deflected by the collective blanking deflector 212 passes through the center hole of the limiting aperture substrate 213 as shown in FIG. 1. By turning the collective blanking deflector 212 ON / OFF, blanking control is performed, and the ON / OFF of the beam is collectively controlled. In this way, the limiting aperture substrate 213 shields the multi-primary electron beam 20 deflected to the beam OFF state by the collective blanking deflector 212. Then, a multi-primary electron beam 20 for image acquisition is formed by the beam group that has passed through the limiting aperture substrate 213 and is formed from the time when the beam is ON until it becomes OFF.

[0036] When the multi-primary electron beam 20 is irradiated on a desired position of the substrate 101, a bundle of secondary electrons including reflected electrons (multi-secondary electron beam 300) corresponding to each beam of the multi-primary electron beam 20 is emitted from the substrate 101 due to the irradiation of such multi-primary electron beam 20.

[0037] The multi-secondary electron beam 300 emitted from the substrate 101 passes through the electromagnetic lens 207 and proceeds to the E×B separator 214. The E×B separator 214 has a plurality of magnetic poles of two or more poles using coils and a plurality of electrodes of two or more poles. For example, it has four-pole magnetic poles (electromagnetic deflection coils) with phases shifted by 90° each and four-pole electrodes (electrostatic deflection electrodes) also with phases shifted by 90° each. And, for example, by setting the opposing two-pole magnetic poles as the N pole and the S pole, a directional magnetic field is generated by such a plurality of magnetic poles. Similarly, for example, by applying voltages V with opposite signs to the opposing two-pole electrodes, a directional electric field is generated by such a plurality of electrodes. Specifically, the E×B separator 214 generates an electric field and a magnetic field in directions orthogonal to each other on a plane orthogonal to the direction (orbit center axis) in which the central beam of the multi-primary electron beam 20 travels. The electric field exerts a force in the same direction regardless of the traveling direction of the electrons. 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 intrusion direction of the electrons. In the multi-primary electron beam 20 that intrudes into the E×B separator 214 from above, the force by the electric field and the force by the magnetic field cancel each other out, and the multi-primary electron beam 20 travels straight downward. In contrast, in the multi-secondary electron beam 300 that intrudes into the E×B separator 214 from below, both the force by the electric field and the force by the magnetic field act in the same direction, and the multi-secondary electron beam 300 is bent obliquely upward and separated from the orbit of the multi-primary electron beam 20.

[0038] The multi-secondary electron beam 300 bent obliquely upward is further bent by the deflector 218 and projected onto the multi-detector 222 while being refracted by the electromagnetic lens 224.

[0039] The multi-detector 222 detects the multi-secondary electron beam 300 projected through the openings of the detector aperture array substrate 225. Each beam of the multi-primary electron beam 20 collides with a detection element corresponding to each secondary electron beam of the multi-secondary electron beam 300 on the detection surface of the multi-detector 222, amplifying and generating electrons to generate secondary electron image data for each pixel. The intensity signal detected by the multi-detector 222 is output to the detection circuit 106. Each primary electron beam is irradiated within a sub-irradiation region surrounded by the beam pitch in the x-direction and the beam pitch in the y-direction where its own beam is located on the substrate 101, and scans (scans) within the sub-irradiation region.

[0040] Also, tracking control is performed by deflecting the multi-primary electron beam 20 by the deflectors 208 and 209 so as to follow the continuous movement of the stage 105. Due to such beam deflection by tracking control and scanning on the substrate 101 with the multi-primary electron beam 20, the emission positions of the secondary electron beams corresponding to each primary electron beam change moment by moment. Therefore, as it is, each secondary electron beam will deviate from its corresponding detection element. For this reason, by collectively performing the return deflection of the multi-secondary electron beam 300 by the deflector 225, the positions of the secondary electron beams on the detection surface of the multi-detector 222 are made immovable. Thereby, each secondary electron beam can be incident on its corresponding detection element.

[0041] As described above, the acquisition of the secondary electron image is performed by irradiating the substrate 101 with the multi-primary electron beam 20 and detecting the multi-secondary electron beam 300 emitted from the substrate 101 due to the irradiation of the multi-primary electron beam 20 with the multi-detector 222.

[0042] FIG. 3 is a diagram showing an example of an objective lens in the comparative example of Embodiment 1. In FIG. 3, in the comparative example, an electromagnetic lens 407 in which a coil 440 is surrounded by a yoke 442 is shown. In the example of FIG. 3, a cross section of the right half is shown with respect to the orbital central axis of the electron beam. The illustration of the left half is omitted. In the comparative example, an example of a semi-in lens type objective lens 407 is shown in which the gap G of the objective lens 407 is directed downward and a sample is placed below the objective lens 407. In the semi-in lens method, by reducing the distance (WD: working distance) between the lower surface of the objective lens and the sample, high resolution equivalent to that of an in-lens type electromagnetic lens can be achieved. Also, like an out-lens type electromagnetic lens, it can be used for a sample having a size larger than the diameter of the inner circumference of the yoke of the electromagnetic lens. At that time, a negative retardation potential is applied to the sample, and a ground (GND) potential is applied to the yoke 442 of the electromagnetic lens. Therefore, an electric field is generated between the lower surface of the objective lens and the sample. Here, the electron beam is affected by aberration due to the processing accuracy of the components and the assembly accuracy of the apparatus. Therefore, usually, as much as possible, the processing accuracy and assembly accuracy are made non-existent, but since there are mechanical limitations, correction is performed using, for example, a deflection electromagnetic lens or the like. In the edge processing of components, it is very difficult to uniformly perform R processing or chamfering processing with a desired size. Therefore, non-uniformity on the circumference becomes a major problem in terms of the influence on aberration. Therefore, it is necessary to consider the influence of extra aberration. Therefore, by making the shape such that chamfering processing and R processing are not performed on the corner portions (edge portions) of the yoke end face of the objective lens, the influence of aberration is reduced. However, as a result, there is a problem that electric field concentration occurs at the corner portions of the yoke end face and discharge may occur.

[0043] Therefore, in Embodiment 1, such electric field concentration occurring at the corner portions of the yoke end face is avoided or reduced. This will be specifically described below.

[0044] FIG. 4 is a diagram showing an example of an objective lens in Embodiment 1. In FIG. 4, an electromagnetic lens 207 serving as an objective lens includes a coil 40, a yoke (also referred to as a pole piece) 42, and a cover 44. In the example of FIG. 4, a right - half cross - section is shown with respect to the orbital central axis 11 of the multi - primary electron beam 20. Illustration of the left - half is omitted.

[0045] The coil 40 is arranged in an annular shape so as to surround the passing region of the multi - primary electron beam 20.

[0046] The yoke 42 is formed of a magnetic material. Also, the yoke 42 is formed of a conductor. The yoke 42 has an upper wall 12, an outer peripheral wall 16, an inner peripheral wall 18, and an inclined wall 14, each having a thickness. The yoke 42 is arranged in an annular shape so as to surround the passing region of the multi - primary electron beam 20 and surrounds the coil 40. In other words, the coil 40 is surrounded by the upper wall 12, the outer peripheral wall 16, the inner peripheral wall 18, and the inclined wall 14. Also, the yoke 42 is configured such that the multi - primary electron beam 20 passes through the space surrounded by the inner peripheral wall 18. Note that the upper wall 12 is arranged on the upstream side in the traveling direction of the passing multi - primary electron beam 20.

[0047] The upper wall 12 and the inclined wall 14 are formed in a concentric - disk shape with a central opening. The outer peripheral wall 16 and the inner peripheral wall 18 are formed in concentric - cylindrical shapes with different diameter sizes. The distance between the upper wall 12 and the inclined wall 14 is set to a size that can sandwich the coil 40 therebetween. The distance between the outer peripheral wall 16 and the inner peripheral wall 18 is set to a size that can sandwich the coil 40 therebetween.

[0048] In the example of FIG. 4, the inclined wall 14 is arranged continuously from the end of the outer peripheral wall 16, and the cross-section extends obliquely toward the inner peripheral side so as to taper on the downstream side in the traveling direction of the multi-primary electron beam 20. Then, a gap G is formed between the downstream end of the multi-primary electron beam 20 of the inner peripheral wall 18 and the downstream end of the multi-primary electron beam 20 of the inclined wall 14 in the traveling direction of the multi-primary electron beam 20. In other words, the inclined wall 14 forms a gap G on the downstream side in the traveling direction of the multi-primary electron beam 20. In the example of FIG. 4, the downstream end face of the multi-primary electron beam 20 of the inner peripheral wall 18 and the downstream end face of the multi-primary electron beam 20 of the inclined wall 14 in the traveling direction of the multi-primary electron beam 20 are arranged at the same height position.

[0049] In Embodiment 1, as shown in FIG. 4, a semi-in-lens type objective lens is configured in which the gap G of the objective lens 207 is directed downward and the substrate 101 is arranged below the objective lens 207. As described above, in the semi-in-lens type, by reducing the distance (WD: working distance) between the lower surface of the objective lens and the sample, an image with the same high resolution as that of the in-lens type electromagnetic lens can be obtained. Also, similar to the out-lens type electromagnetic lens, it can be used for a sample having a size larger than the diameter of the inner circumference of the yoke of the electromagnetic lens. At that time, a negative retardation potential is applied to the substrate 101, and a ground (GND) potential is applied to the yoke 42. For this reason, an electric field is generated between the lower surface of the objective lens and the sample. In addition, the corner portions (edge portions) of the end faces of the yoke 42 of the objective lens 207 are not chamfered or R-processed in order to reduce the influence of aberration. As it is, as described with reference to FIG. 3, electric field concentration occurs at the corner portions of the yoke end face. Therefore, in Embodiment 1, the yoke end face is covered with a cover 44.

[0050] The cover 44 contacts and covers an end face including the inner peripheral side corner on the downstream side in the traveling direction of the multi-primary electron beam 20 of the yoke 42. The cover 44 is formed of a non-magnetic conductor. For example, it is preferable to use titanium (Ti), gold (Ag), or beryllium copper (BeCu). In the example of FIG. 4, since the outer peripheral side corner of the end face on the downstream side of the yoke 42 is formed at an obtuse angle sufficiently larger than 90°, electric field concentration hardly occurs. Therefore, in the example of FIG. 4, the cover 44 covers the inner peripheral side corner formed at an angle of about 90° among both corner portions of the end face on the downstream side. When both corner portions are formed at an angle of 90° or less, or an angle not sufficiently larger than 90° (for example, 120° or less), it is preferable to cover both corner portions with the cover 44.

[0051] The cover 44 is disposed on both sides of the gap G respectively. Specifically, the cover 44 includes a cover member 48 (first cover member) that covers an end face including the inner peripheral side corner of the downstream end in the traveling direction of the multi-primary electron beam 20 of the inner wall 18, and a cover member 46 (second cover member) that covers an end face including the inner peripheral side corner of the downstream end in the traveling direction of the multi-primary electron beam 20 of the inclined wall 14. The cover member 48 is preferably press-fitted and fixed to the end face of the inner wall 18. Similarly, the cover member 46 is preferably press-fitted and fixed to the end face of the inclined wall 14. Thereby, a plurality of screws and stays (supporting members) for connecting the cover members 46 and 48, which are factors of aberration, can be made unnecessary. Further, since the cover members 46 and 48 are only disposed on the end face including the inner peripheral side corner of the downstream end of the yoke 42, for example, interference with the mirror 216 can be prevented even when the stage moves.

[0052] Further, the cover 44 has corners formed as curved surfaces. In other words, the two cover members 46 and 48 each have corners formed as curved surfaces. The radius of curvature of the curved surface of the corner of the cover 44 is set such that the electric field strength at the corner becomes equal to or less than a threshold value in a state where a ground potential is applied to the yoke 42 and a retarding potential is applied to the substrate 101. For example, it is preferable to use 6 kV / mm or less as the threshold value.

[0053] Further, the cover 44 covers both the downstream end face of the yoke 42 facing the substrate in the traveling direction of the multi-electron beam and a part of the inner peripheral surface facing the orbital central axis of the multi-electron beam continuing from such downstream end face. Thereby, the inner peripheral side corner portion of the downstream end face is covered. And it is preferable that the thicknesses d2 and d3 (first thickness) covering a part of the inner peripheral surface are formed to be larger than the thickness d1 (second thickness) covering the downstream end face. Thereby, while reducing the thickness d1 of the cover 44 covering the downstream end face, the radius of curvature R of the curved surface of the corner portion can be increased. The thicknesses d2 and d3 may be the same thickness or different thicknesses. In order to increase the radius of curvature R of the curved surface of the corner portion, it is necessary to increase at least one of the thickness d1 or the thicknesses d2 and d3 according to the size of the radius of curvature R. If the thickness d1 is increased, the distance from the substrate 101 becomes smaller, so the electric field strength at the yoke end face becomes larger. As a result, discharge is likely to occur. On the contrary, by increasing the thicknesses d2 and d3 by the amount by which the thickness d1 is reduced, it is possible to suppress an increase in the electric field strength at the yoke end face. Therefore, the risk of discharge can be reduced. Further, if the thickness d1 of the cover 44 covering the downstream end face is increased, the WD will be reduced accordingly. By making the thicknesses d2 and d3 (first thickness) covering a part of the inner peripheral surface larger than the thickness d1 (second thickness) covering the downstream end face, the radius of curvature R of the curved surface of the corner portion can be increased while maintaining the allowable WD. By increasing the radius of curvature of the curved surface of the corner portion, the electric field concentration can be further alleviated. It is preferable that the thicknesses of the downstream end faces of the two cover members 46 and 48 are both set to d1.

[0054] FIG. 5 is a diagram showing another example of the objective lens in Embodiment 1. In the example of FIG. 5, a right half cross-section is shown with respect to the orbital central axis 11 of the multi-primary electron beam 20. The illustration of the left half is omitted. In the example of FIG. 5, it is the same as FIG. 4 except that a lower wall 15 is arranged instead of the inclined wall 14. The coil 40 is surrounded by the upper wall 12, the outer peripheral wall 16, the inner peripheral wall 18, and the lower wall 15. The lower wall 15 is formed in a concentric disk shape with an opening at the center. Then, a gap G is formed between the downstream end portion of the inner peripheral wall 18 in the traveling direction of the multi-primary electron beam 20 and the inner peripheral side end portion of the lower wall 15. In other words, the lower wall 15 forms a gap G on the downstream side in the traveling direction of the multi-primary electron beam 20. In the example of FIG. 5, it is preferable that the downstream end face of the inner peripheral wall 18 in the traveling direction of the multi-primary electron beam 20 and the downstream side face of the lower wall 15 in the traveling direction of the multi-primary electron beam 20 are arranged at the same height position.

[0055] The cover 44 has a cover member 48 (first cover member) that covers the end face including the inner peripheral side corner portion of the downstream end of the inner wall 18 in the traveling direction of the multi-primary electron beam 20, and a cover member 46 (second cover member) that covers the end face including the inner peripheral side corner portion of the downstream end of the lower wall 15 in the traveling direction of the multi-primary electron beam 20. Also in the example of FIG. 5, as in the case of FIG. 4, it is preferable that the thicknesses d2 and d3 (first thickness) covering a part of the inner peripheral surface are formed to be larger than the thickness d1 (second thickness) covering the downstream end face. In the example of FIG. 5, it is preferable that the cover member 46 covers a part of the outer peripheral surface continuing from the downstream end face of the lower wall 15 with a thickness d2.

[0056] FIG. 6 is a diagram showing the analysis result by simulation of the electric field at the yoke end in the comparative example of Embodiment 1 without a cover. FIG. 7 is a diagram showing the analysis result by simulation of the electric field at the yoke end in the state with the cover in Embodiment 1. As shown in FIG. 6, in the state without the cover at the yoke end, electric field concentration occurred, and under predetermined conditions, an electric field strength of approximately 13 kV / mm at maximum was shown. On the other hand, as shown in FIG. 7, in the state with the cover 44 at the yoke end, the electric field concentration was greatly alleviated, and it was possible to suppress the electric field strength to 6 kV / mm or less which is the threshold value.

[0057] Next, the substrate 101 is inspected using the electromagnetic lens 207 in which discharge could be avoided or reduced.

[0058] FIG. 8 is a diagram for explaining the inspection region and inspection method in Embodiment 1. In FIG. 8, when the substrate 101 is a mask substrate, the inspection region 330 of the mask substrate is divided into a plurality of stripe regions 32 with a predetermined width in the y direction, for example. The scanning operation by the image acquisition mechanism 150 is carried out for each stripe region 32, for example. For example, while moving the stage 105 in the -x direction, the scanning operation of the stripe region 32 is advanced relatively in the x direction. Each stripe region 32 is divided into a plurality of rectangular regions 33 in the longitudinal direction. The movement of the beam to the target rectangular region 33 is performed by batch deflection of the entire multi-primary electron beam 20 by the deflectors 208 and 209.

[0059] In the example of FIG. 8, for example, the case of a 5×5 column multi-primary electron beam 20 is shown. The irradiation region 34 that can be irradiated by one irradiation of the multi-primary electron beam 20 is defined as (the x-direction size obtained by multiplying the beam pitch in the x direction of the multi-primary electron beam 20 on the substrate 101 surface by the number of beams in the x direction)×(the y-direction size obtained by multiplying the beam pitch in the y direction of the multi-primary electron beam 20 on the substrate 101 surface by the number of beams in the y direction). The irradiation region 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 within a sub-irradiation region 29 surrounded by the beam pitch in the x direction and the beam pitch in the y direction where its own beam is located, and scans (scanning operation) within the sub-irradiation region 29. Each primary electron beam 10 will be in charge of a different sub-irradiation region 29. And at each shot, each primary electron beam 10 will irradiate the same position within the sub-irradiation region 29 in charge. The movement of the primary electron beam 10 within the sub-irradiation region 29 is performed by collective deflection of the entire multi-primary electron beam 20 by the deflectors 208 and 209. By repeating such an operation, one primary electron beam 10 sequentially irradiates within one sub-irradiation region 29.

[0060] 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 a size that is narrower by the scan margin. In the example of FIG. 8, the case where the irradiation region 34 has the same size as the rectangular region 33 is shown. However, it is not limited to this. The irradiation region 34 may be smaller than the rectangular region 33 or may be larger. And each primary electron beam 10 that constitutes the multi-primary electron beam 20 is irradiated within the sub-irradiation region 29 where its own beam is located and scans (performs a scanning operation) within the sub-irradiation region 29. Then, when the scan of one sub-irradiation region 29 is completed, the irradiation position moves to an adjacent rectangular region 33 within the same stripe region 32 by a batch deflection of the entire multi-primary electron beam 20 by the deflectors 208, 209. Such an operation is repeated to sequentially irradiate within the stripe region 32. When the scan of one stripe region 32 is completed, the irradiation region 34 moves to the next stripe region 32 by the movement of the stage 105 or / and a batch deflection of the entire multi-primary electron beam 20 by the deflectors 208, 209. As described above, the scanning operation for each sub-irradiation region 29 and the acquisition of the secondary electron image are performed by the irradiation of each primary electron beam 10. By combining the secondary electron images for each of these sub-irradiation regions 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 inspection region 330 is constituted. Also, when actually performing image comparison, the sub-irradiation regions 29 within each rectangular region 33 are further divided into a plurality of frame regions 30, and the frame images 31 for each frame region 30 are compared. In the example of FIG. 8, the case of dividing the sub-irradiation region 29 scanned by one primary electron beam 10 into four frame regions 30 formed by dividing it into two in the x and y directions respectively is shown.

[0061] Here, when the stage 105 continuously moves while irradiating the substrate 101 with the multi-primary electron beam 20, the deflectors 208 and 209 perform a tracking operation by batch deflection so that the irradiation position of the multi-primary electron beam 20 follows the movement of the stage 105. Therefore, the emission position of the multi-secondary electron beam 300 changes moment by moment with respect to the orbital central axis of the multi-primary electron beam 20. Similarly, when scanning within the sub-irradiation region 29, the emission position of each secondary electron beam changes moment by moment within the sub-irradiation region 29. The deflector 225 batch deflects the multi-secondary electron beam 300 so that each secondary electron beam with a changed emission position is irradiated into the corresponding detection region of the multi-detector 222.

[0062] As described above, the image acquisition mechanism 150 proceeds with the scanning operation for each stripe region 32. The image (secondary electron image) used for inspection is obtained by irradiating the substrate 101 to be inspected on the stage 105 with the multi-primary electron beam 20 and the multi-detector 222 detecting the multi-secondary electron beam 300 emitted from the substrate 101 by the irradiation of the multi-primary electron beam 20. The detected multi-secondary electron beam 300 may contain reflected electrons. Alternatively, the reflected electrons may be separated during the movement of the secondary electron optical system 152 and may not reach the multi-detector 222. The detection data (measurement image data: secondary electron image data: inspected image data) of the secondary electrons for each pixel within each sub-irradiation region 29 detected by the multi-detector 222 is output to the detection circuit 106 in the order of measurement. In the detection circuit 106, the analog detection data is converted into digital data by an A / D converter (not shown) and stored in the chip pattern memory 123. Then, the obtained measurement image data is transferred to the comparison circuit 108 together with the information indicating each position from the position circuit 107.

[0063] FIG. 9 is a configuration diagram showing an example of the configuration within the comparison circuit in Embodiment 1. In FIG. 9, within the comparison circuit 108, storage devices 50, 52, 56 such as magnetic disk devices, a frame image creation unit 54, an alignment unit 57, and a comparison unit 58 are arranged. Each "~ unit" such as the frame image creation unit 54, the alignment unit 57, and the comparison unit 58 includes a processing circuit, and the processing circuit includes an electric circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device, etc. Also, each "~ unit" may use a common processing circuit (the same processing circuit). Alternatively, different processing circuits (separate processing circuits) may be used. 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 each time) or the memory 118 each time.

[0064] The measurement image data (beam image) transferred into the comparison circuit 108 is stored in the storage device 50.

[0065] Then, the frame image creation unit 54 creates frame images 31 for each of the plurality of frame regions 30 obtained by further dividing the image data of the sub-irradiation region 29 acquired by the scanning operation of each primary electron beam 10. And the frame region 30 is used as a unit region of the image to be inspected. Note that it is preferable that each frame region 30 is configured such that the margin regions overlap each other so that there is no missing part in the image. The created frame images 31 are stored in the storage device 56.

[0066] On the other hand, 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 is the basis of the plurality of graphic patterns formed on the substrate 101. Specifically, it operates as follows. First, the design pattern data is read from the storage device 109 through the control computer 110, and each graphic pattern defined in the read design pattern data is converted into binary or multi-valued image data.

[0067] As described above, the shapes defined in the design pattern data are based on basic shapes such as rectangles and triangles. For example, shape data that defines the shape, size, position, etc. of each pattern shape with information such as the coordinates (x, y) at the reference position of the shape, the side length, and a shape code that serves as an identifier for distinguishing shape types such as rectangles and triangles is stored.

[0068] When such design pattern data that becomes such shape data is input to the reference image creation circuit 112, it is expanded into data for each shape, and the shape code indicating the shape of the shape data, the shape dimensions, etc. are interpreted. Then, it is expanded into binary or multi-valued design pattern image data as a pattern arranged in a grid with a predetermined quantization dimension as a unit and output. In other words, the design data is read, the inspection area is virtually divided into grids with a predetermined dimension as a unit, and the occupancy rate occupied by the shape in the design pattern is calculated for each grid, and n-bit occupancy rate data is output. For example, it is suitable to set one grid as one pixel. And if a resolution of 1 / 2 8 (=1 / 256) is given, a small area of 1 / 256 is allocated for the area of the shape arranged in the pixel, and the occupancy rate in the pixel is calculated. And it becomes 8-bit occupancy rate data. Such a grid (inspection pixel) may be matched with the pixel of the measurement data.

[0069] Next, the reference image creation circuit 112 performs a filtering process on the design image data of the design pattern, which is the image data of the shape, using a predetermined filter function. Thereby, the design image data, which is the image data on the design side where the image intensity (shading value) is a digital value, can be adjusted to the image generation characteristics obtained by the irradiation of the multi-primary electron beam 20. The image data for each pixel of the created reference image is output to the comparison circuit 108. The reference image data transferred into the comparison circuit 108 is stored in the storage device 52.

[0070] Next, the alignment unit 57 reads out the frame image 31 that becomes the inspection target image 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, alignment may be performed by the least squares method.

[0071] Then, the comparison unit 58 compares the secondary electron image of the substrate 101 placed on the stage 105 with a predetermined image. Specifically, the comparison unit 58 compares the frame image 31 and the reference image pixel by pixel. The comparison unit 58 compares the two pixel by pixel according to a predetermined determination condition, and determines the presence or absence of a defect such as a shape defect. For example, if the gradation value difference per pixel is larger than the determination threshold Th, it is determined as a defect. Then, the comparison result is output. The comparison result may be output to the storage device 109, or the memory 118, or may be output from the printer 119.

[0072] Note that, in the above example, the die-database inspection has been described, but the present invention is not limited to this. The die-die inspection may be performed. In the case of performing the die-die inspection, the above-described alignment and comparison processes may be performed between the target frame image 31 (die 1) and the frame image 31 (die 2) (another example of the reference image) in which the same pattern as the frame image 31 is formed.

[0073] As described above, according to the first embodiment, discharge between the electromagnetic lens 207 (objective lens) and the substrate 101 (sample) can be suppressed.

[0074] In the above description, a series of "~ circuits" includes a processing circuit, and the processing circuit includes an electric circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device, etc. Also, each "~ circuit" may use a common processing circuit (the same processing circuit), or may use different processing circuits (separate processing circuits). The program for causing a processor or the like to execute may be recorded on a recording medium such as a magnetic disk device, a magnetic tape device, an FD, or a ROM (read-only memory). For example, the position circuit 107, the comparison circuit 108, the reference image creation circuit 112, etc. may be configured by at least one of the above-described processing circuits.

[0075] As described above, the embodiments have been described with reference to specific examples. However, the present invention is not limited to these specific examples.

[0076] Also, parts that are not directly necessary for the description of the present invention, such as the device configuration and control method, etc., have been omitted, but the required device configuration and control method can be appropriately selected and used.

[0077] In addition, all electromagnetic lenses, scanning electron microscopes, and multi-electron beam inspection devices that have the elements of the present invention and can be appropriately designed and modified by those skilled in the art are included in the scope of the present invention.

Explanation of Reference Numerals

[0078] 10 Primary electron beam 11 Orbit central axis 12 Upper wall 14 Diagonal wall 15 Lower wall 16 Outer peripheral wall 18 Inner peripheral wall 20 Multi-primary electron beam 22 Hole 29 Sub-irradiation region 30 Frame region 31 Frame image 32 Stripe region 33 Rectangular region 34 Irradiation region 40 Coil 42 Yoke 44 Cover 46, 48 Cover member 50, 52, 56 Memory device 54 Frame image creation unit 57 Alignment unit 58 Comparison unit 100 Inspection device 101 Substrate 102 Electron beam column 103 Inspection chamber 105 Stage 106 Detection circuit 107 Position circuit 108 Comparison circuit 109 Memory device 110 Control computer 111 Mark 112 Reference image creation circuit 114 Stage control circuit 117 Monitor 118 Memory 119 Printer 120 Bus 122 Laser length measurement system 123 Chip pattern memory 124 Lens control circuit 126 Blanking control circuit 128 Deflection control circuit 130 Retarding control circuit 132 E×B separator control circuit 142 Stage drive mechanism 144, 146, 147 DAC amplifier 148 DC power supply 150 Image acquisition mechanism 151 Primary electron optical system 152 Secondary electron optical system 160 Control system circuit 200 Electron beam 201 Electron gun 202, 205 Electromagnetic lens 203 Shaping aperture array substrate 206, 207 Electromagnetic lens 208 Deflector 209 Deflector 212 Batch Deflector 213 Restriction Aperture Substrate 214 E×B Separator 216 Mirror 218 Deflector 222 Multi-Detector 224 Electromagnetic Lens 225 Deflector 300 Multi-Scattered Electron Beam 330 Inspection Area 407 Objective Lens 440 Coil 442 Yoke

Claims

1. A coil, formed of a magnetic material, having an upper wall, an outer peripheral wall, and an inner peripheral wall on the upstream side in the traveling direction of the primary electron beam passing therethrough, and a lower wall having a gap formed on the downstream side in the traveling direction of the primary electron beam or an inclined wall forming a gap on the downstream side in the traveling direction of the primary electron beam, configured such that the primary electron beam passes through the space surrounded by the inner peripheral wall, and a yoke surrounding the coil by the upper wall, the outer peripheral wall, the inner peripheral wall, and the lower wall or the inclined wall, a cover formed of a non-magnetic conductor, covering and contacting an end surface including an inner peripheral side corner portion at the downstream end of the yoke in the traveling direction of the primary electron beam, and having a corner portion formed as a curved surface, An electromagnetic lens characterized by comprising the above.

2. On the downstream side in the traveling direction of the primary electron beam of the electromagnetic lens, a substrate irradiated with the primary electron beam and to which a retarding potential is applied is disposed, The radius of curvature of the curved surface of the corner portion of the cover is set such that the electric field strength at the corner portion is equal to or less than a threshold value in a state where a ground potential is applied to the yoke and the retarding potential is applied to the substrate. The electromagnetic lens according to Claim 1.

3. The cover, a first cover member covering the downstream end surface of the inner wall in the traveling direction of the primary electron beam, a second cover member covering an end surface including an inner peripheral side corner portion at the downstream end of the lower wall or the inclined wall in the traveling direction of the primary electron beam, The electromagnetic lens according to Claim 1 or 2, characterized by comprising the above.

4. The cover also covers a part of the inner peripheral surface continuing from the downstream end surface of the yoke in the traveling direction of the multi-electron beam, The electromagnetic lens according to Claim 1 or 2, characterized in that a first thickness covering a part of the inner peripheral surface is larger than a second thickness covering the downstream end surface.

5. A coil, formed of a magnetic material, having an upper wall, an outer peripheral wall, and an inner peripheral wall on the upstream side in the traveling direction of the primary electron beam passing therethrough, and a lower wall having a gap formed on the downstream side in the traveling direction of the primary electron beam or an inclined wall forming a gap on the downstream side in the traveling direction of the primary electron beam, configured such that the primary electron beam passes through the space surrounded by the inner peripheral wall, and a yoke surrounding the coil by the upper wall, the outer peripheral wall, the inner peripheral wall, and the lower wall or the inclined wall, A cover formed of a non-magnetic conductor that contacts and covers an end face including an inner peripheral side corner portion at the downstream end in the traveling direction of the primary electron beam of the yoke, and having a curved corner portion; An electromagnetic lens having; A stage on which a sample that receives irradiation of the primary electron beam that has passed through the electromagnetic lens is placed; A detector that detects a secondary electron beam emitted from the sample; A scanning electron microscope characterized by comprising.

6. A coil; Formed of a magnetic material, having an upper wall, an outer peripheral wall, and an inner peripheral wall on the upstream side in the traveling direction of the primary electron beam passing therethrough, and a lower wall having a gap formed on the downstream side in the traveling direction of the primary electron beam or an inclined wall that forms a gap on the downstream side in the traveling direction of the primary electron beam, configured such that the primary electron beam passes through the space surrounded by the inner peripheral wall, and a yoke that surrounds the coil with the upper wall, the outer peripheral wall, the inner peripheral wall, and the lower wall or the inclined wall; A cover formed of a non-magnetic conductor that contacts and covers an end face including an inner peripheral side corner portion at the downstream end in the traveling direction of the primary electron beam of the yoke, and having a curved corner portion; An electromagnetic lens having; A stage on which a sample that receives irradiation of the primary electron beam that has passed through the electromagnetic lens is placed; A detector that detects a secondary electron beam emitted from the sample; An electron beam inspection apparatus characterized by comprising.

Images