Multi-electron beam adjustment method and multi-electron beam inspection device

Abstract

To provide an adjustment method that enables multiple primary electron beams to be focused on a substrate to be inspected and enables an intermediate image plane to be formed near the center position of a deflector on the trajectory of multiple secondary electron beams separated from the multiple primary electron beams.SOLUTION: An adjustment method according to an aspect of the present invention includes the steps of acquiring a secondary electron image in which both a pattern image and an aperture image are captured together by scanning a substrate or a mark with a representative primary electron beam for each combination of input values of first and second lenses that guide the multiple primary electron beams to the substrate and a third lens that guides the multiple secondary electron beams to a detector, scanning an aperture substrate with a representative secondary electron beam to be discharged, and detecting the representative secondary electron beam with a detector. The adjustment method further includes a step of acquiring a combination of input values of each lens that focuses the representative secondary electron beam at a predetermined position of a first deflector, using the secondary electron image for each combination of input values of the first, second, and third lenses.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a method for adjusting multiple electron beams and a multiple electron beam inspection device, for example, to a multi-beam inspection device that performs pattern inspection using a secondary electron image caused by 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 elements has become increasingly narrow. Furthermore, improving the yield is essential for the manufacture of LSIs, which incur huge manufacturing costs. However, as typified by 1-gigabit-class DRAMs (random access memories), the patterns that make up LSIs are on the order of submicrons to nanometers. In recent years, with the miniaturization of LSI pattern dimensions formed on semiconductor wafers, the dimensions that must be detected as pattern defects have also become extremely small. Therefore, in order to inspect defects in ultra-fine patterns transferred onto semiconductor wafers, it is necessary to capture high-precision images.

[0003] In the inspection device, for example, a multi-primary electron beam using an electron beam is focused on a substrate to be inspected, the substrate to be inspected is scanned with the multi-primary electron beam, and the multi-secondary electron beam emitted from the substrate to be inspected is separated from the trajectory of the multi-primary electron beam. Then, the separated multi-secondary electron beam is guided to a detector (see, for example, Patent Document 1). Then, the multi-secondary electron beam is detected by the detector to capture a pattern image. In order to guide the multi-secondary electron beam to the multi-detector, the separated multi-secondary electron beam is further deflected by a deflector. Here, in order to capture an image of each secondary electron beam with the multi-detector, the multi-secondary electron beam needs to be separated from each other on the detection surface of the multi-detector. However, it is not possible to separate the multi-secondary electron beams sufficiently by simply irradiating the pattern image of the sample on the stage on the detection surface of the multi-detector. In order to separate the multi-secondary electron beams from each other on the detection surface of the multi-detector, it is necessary to form an intermediate image plane of the multi-secondary electron beam near the center position of the deflector.

[0004] However, conventionally, there was no method for focusing multiple primary electron beams on the substrate to be inspected and then imaging multiple secondary electron beams near the center position of the deflector, so the lenses had to be adjusted, for example, by simulation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2003-132834 A Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, one aspect of the present invention provides a method and apparatus that can focus multiple primary electron beams on a substrate to be inspected and adjust a lens upstream of a deflector so as to form an intermediate image plane of the multiple secondary electron beams near the center position of the deflector on the trajectory of the multiple secondary electron beams separated from the trajectory of the multiple primary electron beams. [Means for solving the problem]

[0007] A method for adjusting multiple electron beams according to one aspect of the present invention includes the steps of: a separator for separating multiple secondary electron beams emitted due to irradiation of a substrate or a mark with the multiple primary electron beams from the multiple primary electron beams; first and second lenses disposed between the separator and the substrate to guide the multiple primary electron beams to the substrate; a first deflector that deflects the multiple secondary electron beams separated from the multiple primary electron beams by the separator toward a detector having an aperture plate with an opening disposed on a detection element; a third lens disposed between the first deflector and the detector, the third lens directing the multiple secondary electron beams to the detector; A method for adjusting multiple electron beams of a multiple electron beam image acquisition apparatus, comprising: selecting one representative primary electron beam from the multiple primary electron beams; a step of acquiring a secondary electron image in which both a pattern image obtained by scanning the substrate or mark with the representative primary electron beam and an aperture image obtained by scanning the aperture substrate with the representative secondary electron beam are captured by scanning the substrate or mark with the representative primary electron beam for each combination of variable input values ​​to the first, second, and third lenses, by scanning the substrate or mark with the representative primary electron beam, and detecting the scanned representative secondary electron beam with a detector; a step of acquiring a combination of a first focus input value of a first lens, of the first and second lenses, which is disposed on the separator side and focuses the representative secondary electron beam on a predetermined position of the first deflector, a second focus input value of a second lens which focuses the representative primary electron beam on a substrate or a mark, and a third focus input value of a third lens which focuses the representative secondary electron beam on a detector, using a secondary electron image for each combination of input values ​​to the first, second, and third lenses; setting a first focus input value of the obtained combination to a first lens and setting a second focus input value of the obtained combination to a second lens; The present invention is characterized by comprising:

[0008] In addition, when acquiring a secondary electron image for each combination of input values ​​of the first, second, and third lenses, it is preferable to use a second deflector arranged between the separator and the substrate to scan the substrate or mark with a representative primary electron beam and to scan the aperture substrate with a representative secondary electron beam emitted from the substrate or mark.

[0009] Alternatively, when acquiring a secondary electron image for each combination of input values ​​of the first, second and third lenses, it is preferable to use a second deflector arranged between the separator and the substrate to scan the substrate or mark with a representative primary electron beam, and to use a third deflector arranged between the first deflector and the detector to scan the aperture substrate with a representative secondary electron beam emitted from the substrate or mark.

[0010] The step of obtaining the combination includes: determining a second focus input value of the second lens so that the pattern image is in focus; determining a third focus input value of the third lens so that the aperture image is in focus; determining a first focus input value of the first lens such that a position change amount of the aperture image becomes equal to or less than a threshold value when a fourth input value of the first deflector is changed; It is preferable to have the following.

[0011] In addition, it is preferable to use a detector in which an aperture substrate having a plurality of openings formed therein is disposed on a detection element.

[0012] A multi-electron beam inspection apparatus according to one aspect of the present invention comprises: a first lens and a second lens adjusted by the above-mentioned method for adjusting a multi-electron beam; A separator as described above; The first deflector described above; The third lens as described above; a detector for detecting the multiple secondary electron beams that have passed through the separator, the first deflector, and the third lens; The present invention is characterized by comprising:

[0013] Moreover, the above-mentioned detector is a first detector, It is preferable to further include a second detector for adjusting the first and second lenses.

[0014] In addition, it is preferable that the detector has an aperture substrate in which a plurality of openings are formed, disposed on one detection element.

[0015] A method for adjusting multiple electron beams according to another aspect of the present invention includes the steps of: a separator for separating the multiple secondary electron beams emitted due to irradiation of the substrate or the mark with the multiple primary electron beams from the multiple primary electron beams; first and second lenses disposed between the separator and the substrate to guide the multiple primary electron beams to the substrate; a first deflector that deflects the multiple secondary electron beams separated from the multiple primary electron beams by the separator toward a detector having an aperture substrate with openings formed therein and disposed on a detection element; a third lens disposed between the first deflector and the detector, the third lens directing the multiple secondary electron beams to the detector; A method for adjusting multiple electron beams of a multiple electron beam image acquisition apparatus, comprising: selecting one representative primary electron beam from the multiple primary electron beams; a step of acquiring a secondary electron image in which both a pattern image obtained by scanning the substrate or mark with the representative primary electron beam and an aperture image obtained by scanning the aperture substrate with the representative secondary electron beam are captured by scanning the substrate or mark with the representative primary electron beam for each combination of variable input values ​​to the first, second, and third lenses, by scanning the substrate or mark with the representative primary electron beam, and detecting the scanned representative secondary electron beam with a detector; a step of focusing the representative secondary electron beam at a predetermined position of the first deflector using a secondary electron image for each combination of input values ​​to the first, second, and third lenses, and acquiring a combination of first and second focus input values ​​of the first and second lenses that focus the representative primary electron beam on the substrate or mark, and a third focus input value of the third lens that focuses the representative secondary electron beam on a detector; setting a first focus input value of the obtained combination to a first lens and setting a second focus input value of the obtained combination to a second lens; The present invention is characterized by comprising:

[0016] A method for adjusting multiple electron beams according to another aspect of the present invention includes the steps of: a separator for separating the multiple secondary electron beams emitted due to irradiation of the substrate or the mark with the multiple primary electron beams from the multiple primary electron beams; first and second lenses disposed between the separator and the substrate to guide the multiple primary electron beams to the substrate; a first deflector that deflects the multiple secondary electron beams separated from the multiple primary electron beams by the separator toward a detector having an aperture substrate with openings formed therein and disposed on a detection element; a third lens disposed between the first deflector and the detector, the third lens directing the multiple secondary electron beams to the detector; A method for adjusting multiple electron beams of a multiple electron beam image acquisition apparatus, comprising: a step of acquiring a secondary electron image in which both a pattern image obtained by scanning the substrate or mark with the multi-primary electron beams and an aperture image obtained by scanning the aperture substrate with the multi-secondary electron beams are captured together, by scanning a substrate or mark with the multi-primary electron beams for each combination of variable combinations of input values ​​to the first, second, and third lenses, scanning an aperture substrate with the multi-secondary electron beams emitted from the substrate or mark by scanning with the multi-primary electron beams, and detecting the scanned multi-secondary electron beams with a detector so that two or more secondary electron beams are not incident on one aperture; acquiring a combination of first and second focus input values ​​of the first and second lenses for focusing the multiple secondary electron beams on a predetermined position of the first deflector and the multiple primary electron beams on a substrate or a mark, and a third focus input value of the third lens for focusing the multiple secondary electron beams on a detector, using the secondary electron image for each combination of input values ​​to the first, second, and third lenses; setting a first focus input value of the obtained combination to a first lens and setting a second focus input value of the obtained combination to a second lens; The present invention is characterized by comprising:

[0017] In addition, a multi-detector is used as the detector, in which an aperture substrate having a plurality of openings formed therein is arranged on a plurality of detection elements so that a different opening is located on each detection element, It is preferable to further include a step of setting a third focus input value of the acquired combination to a third lens.

[0018] Moreover, it is preferable that the aperture size of the plurality of openings is smaller than the beam pitch of the multiple secondary electron beams on the aperture substrate.

[0019] Another aspect of the present invention is a multi-electron beam inspection apparatus. a first lens and a second lens adjusted by the above-mentioned method for adjusting a multi-electron beam; A separator; A first deflector; The third lens, a multi-detector for detecting the multiple secondary electron beams that have passed through the separator, the first deflector, and the third lens; The present invention is characterized by comprising: Effect of the Invention

[0020] According to one aspect of the present invention, the multiple primary electron beams can be focused on a substrate to be inspected, and a lens upstream of the deflector can be adjusted to form an intermediate image plane of the multiple secondary electron beams near the center position of the deflector on the trajectory of the multiple secondary electron beams separated from the trajectory of the multiple primary electron beams. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a configuration diagram showing a configuration of a pattern inspection device according to a first embodiment. [Diagram 2] 2 is a conceptual diagram showing a configuration of a shaping aperture array substrate in the first embodiment. FIG. [Diagram 3] 1 is a diagram showing an example of a plurality of chip regions formed on a semiconductor substrate in the first embodiment. [Figure 4] FIG. 4 is a diagram for explaining an image acquisition process in the first embodiment. [Diagram 5] FIG. 11 is a diagram for explaining an electron beam adjusting method in a comparative example to the first embodiment. [Figure 6] 2 is a block diagram showing an example of a configuration within a beam adjustment circuit in the first embodiment. FIG. [Figure 7] FIG. 4 is a flowchart showing an example of main steps of a multi-electron beam adjustment method in the first embodiment. [Figure 8] FIG. 2 is a top view showing an example of a beam selection aperture substrate in the first embodiment. [Figure 9] FIG. 2 is a diagram for explaining an example of an image acquiring method in the first embodiment. [Figure 10]FIG. 4 is a top view of an example of a detector arranged in place of the multi-detector in the first embodiment. [Figure 11] FIG. 4 is a cross-sectional view of an example of a detector arranged in place of the multi-detector in the first embodiment. [Figure 12] FIG. 3 is a diagram showing an example of a secondary electron image in the first embodiment. [Figure 13] FIG. 4 is a diagram showing an example of a focus adjustment method according to the first embodiment. [Figure 14] FIG. 13 is a diagram for explaining an example of an image acquiring method in the first modification of the first embodiment. [Figure 15] FIG. 13 is a diagram for explaining an example of an image acquiring method in the second modification of the first embodiment. [Figure 16] FIG. 13 is a diagram for explaining an example of an image acquiring method in the third modification of the first embodiment. [Figure 17] FIG. 2 is a top view showing an example of a detector aperture array substrate in the first embodiment. [Figure 18] 1 is a cross-sectional view showing an example of a multi-detector in accordance with the first embodiment. [Figure 19] FIG. 13 is a diagram showing an example of a secondary electron image in Modification 3 of Embodiment 1. [Figure 20] FIG. 13 is a diagram showing another example of the secondary electron image in the third modification of the first embodiment. [Figure 21] 4 is a configuration diagram showing an example of the internal configuration of a comparison circuit according to the first embodiment. FIG. [Figure 22] FIG. 11 is a flowchart showing an example of main steps of a multi-electron beam adjustment method in the second embodiment. [Figure 23] FIG. 11 is a diagram for explaining an example of an image acquiring method in the second embodiment. [Figure 24] FIG. 11 is a diagram showing the relationship between a detector aperture array substrate and multiple secondary electron beams in the second embodiment. [Diagram 25] FIG. 11 is a diagram showing an example of a particle according to the second embodiment. [Figure 26] FIG. 11 is a diagram showing an example of a secondary electron image in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] In the following, in the embodiment, 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, and may be any device that acquires an image using multiple beams.

[0023] Embodiment 1 FIG. 1 is a configuration diagram showing the configuration of a pattern inspection apparatus in the first embodiment. 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 a multi-electron beam image acquisition apparatus. The inspection apparatus 100 includes an image acquisition mechanism 150 and a control system circuit 160 (control unit). The image acquisition mechanism 150 includes an electron beam column 102 (electron lens barrel), an inspection chamber 103, a detection circuit 106, a chip pattern memory 123, a stage driving mechanism 142, and a laser length measurement system 122. Arranged within the electron beam column 102 are an electron gun 201, an illumination lens 202, a shaping aperture array substrate 203, a beam selection aperture substrate 204, a driving circuit 215, an electromagnetic lens 205, a collective deflector 212, a limiting aperture substrate 213, an electromagnetic lens 206, an E×B separator 214 (separator), an electromagnetic lens 217 (first lens), an electromagnetic lens 207 (second lens), deflectors 208, 209, a deflector (bender) 218, a deflector 225, an electromagnetic lens 224 (third lens), a detector aperture array substrate 223, and a multi-detector 222.

[0024] The primary electron optical system 151 (illumination optical system) is configured by the electron gun 201, illumination lens 202, shaping aperture array substrate 203, beam selection aperture substrate 204, electromagnetic lens 205, collective deflector 212, limiting aperture substrate 213, electromagnetic lens 206, E×B separator 214 (separator), electromagnetic lens 217, electromagnetic lens 207, and deflectors 208 and 209. The secondary electron optical system 152 (detection optical system) is configured by the electromagnetic lenses 207 and 217, E×B separator 214, deflector 218, deflector 225, and electromagnetic lens 224.

[0025] The multi-detector 222 has a plurality of detection elements arranged in an array (grid). The plurality of detection elements are composed of detection elements equal to or greater than the number of the multiple secondary electron beams. Since the number of the multiple secondary electron beams 300 is the same as the number of the multiple primary electron beams 20, the plurality of detection elements are composed of detection elements equal to or greater than the number of the multiple primary electron beams 20. A plurality of openings are formed in the detector aperture array substrate 223 at the arrangement pitch of the plurality of detection elements. The plurality of openings are formed, for example, in a rectangular or circular shape. The center position of each opening is formed to match the center position of the corresponding detection element. The size of the openings is also formed to be smaller than the area size of the electron detection surface of the detection element.

[0026] Also, a detector 226 (an example of a second detector) is temporarily placed in the secondary electron optical system 152. The detector 226 has one detection element. For example, a solid-state detector (SSD) is preferably used as the detection element of the detector 226. The detector 226 is placed in a position between the electromagnetic lens 224 and the multi-detector 222, or in the position of the multi-detector 222, instead of the multi-detector 222 (an example of a first detector). When imaging the pattern of the substrate 101 to be inspected, the detector 226 is removed and the multi-detector 222 is placed instead. It is preferable that the detector 226 is moved to a position where it does not interfere with the secondary electron beam orbit in the secondary electron optical system 152 during a period when it is not in use. Alternatively, it may be taken out of the inspection apparatus 100.

[0027] In addition, a deflector 227 is disposed at a position between the electromagnetic lens 224 and the detector 226. Note that the mechanism performed by the deflector 227 can be substituted by the deflector 225, as described later, so the deflector 227 may be omitted.

[0028] In the inspection chamber 103, a stage 105 movable at least in the XY direction 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 dies) 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. The chip pattern formed on the exposure mask substrate is exposed and transferred onto the semiconductor substrate a plurality of times, thereby forming a plurality of chip patterns (wafer dies) on the semiconductor substrate. The following mainly describes the case where the substrate 101 is a semiconductor substrate. The substrate 101 is arranged on the stage 105 with, for example, a pattern forming surface facing upward. In addition, on the stage 105, a mirror 216 is arranged to reflect a laser beam for laser measurement irradiated from a laser measurement system 122 arranged outside the inspection chamber 103. Furthermore, a mark 111 is arranged on the stage 105 at the same height as the surface of the substrate 101. For example, a cross pattern, a plurality of rectangular patterns arranged in an array, and / or a line and space pattern, etc., are formed on the mark 111.

[0029] In addition, 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.

[0030] In the control system circuit 160, a control computer 110 that controls the entire inspection apparatus 100 is connected 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 retarding control circuit 130, an E×B separator control circuit 132, a beam adjustment circuit 134, a storage device 109 such as a magnetic disk device, a monitor 117, a memory 118, and a printer 119 via a bus 120. The deflection control circuit 128 is also connected to DAC (digital-to-analog conversion) amplifiers 144, 146, 147, and 149, and a power supply 148. The DAC amplifier 146 is connected to a deflector 208, and the DAC amplifier 144 is connected to a deflector 209. The DAC amplifier 147 is connected to a deflector 225. The DAC amplifier 149 is connected to a deflector 227. If the deflector 227 is omitted then the DAC amplifier 149 is similarly omitted. A power supply 148 is connected to the deflector 218.

[0031] The chip pattern memory 123 is connected to the comparison circuit 108. The stage 105 is driven by a driving mechanism 142 under the control of the stage control circuit 114. The driving mechanism 142 is configured with a driving system such as a three-axis (XY-θ) motor that drives in the X, Y, and θ directions in the stage coordinate system, and the stage 105 can be moved in the X, Y, and θ directions. These X, Y, and θ motors (not shown) can be, for example, step motors. The stage 105 can be moved in the horizontal and rotational directions by the motors of the X, Y, and θ axes. The moving position of the stage 105 is measured by a laser length measurement system 122 and supplied to a position circuit 107. The laser length measurement system 122 measures the position of the stage 105 by receiving the reflected light from the mirror 216 based on the principle of laser interference. For example, the X, Y, and θ directions of the primary coordinate system are set for the stage coordinate system with respect to a plane perpendicular to the optical axis of the multi-primary electron beams 20.

[0032] The electromagnetic lens 202, the electromagnetic lens 205, the electromagnetic lens 206, the electromagnetic lens 217, the electromagnetic lens 207, and the electromagnetic lens 224 are controlled by the lens control circuit 124. The collective 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 a 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 a DAC amplifier 146 for each electrode. The deflector 225 is composed of four or more electrodes, and is controlled by the deflection control circuit 128 via a DAC amplifier 147 for each electrode.

[0033] Although deflector 225 is shown as a single stage deflector, it may also be preferably configured as a two stage deflector, such as the pair of deflectors 208 and 209. Similarly, deflector 227 is shown as a single stage deflector, but it may also be preferably configured as a two stage deflector, such as the pair of deflectors 208 and 209.

[0034] The deflector 218 (bender) is composed of, for example, a plurality of electrodes facing each other, each formed in a cylindrical shape bent in an arc, and the potential of each electrode is controlled by the deflection control circuit 128 via the power supply 148. Alternatively, the deflector 218 may be composed of two or more electrodes, and the potential of each electrode may be controlled by the deflection control circuit 128 via the power supply 148, thereby improving the uniformity of the deflection electric field.

[0035] The retarding control circuit 130 (potential application circuit) applies a desired retarding potential to the substrate 101 and the mark 111 to adjust the energy of the multiple primary electron beams 20 irradiated onto the substrate 101 and the mark 111 .

[0036] The E×B separator 214 is controlled by the E×B separator control circuit 132 .

[0037] A high-voltage power supply circuit (not shown) is connected to the electron gun 201, and an acceleration voltage from the high-voltage power supply circuit is applied between a filament (not shown) and an extraction electrode (not shown) in the electron gun 201. A predetermined voltage is applied to the extraction electrode (Wehnelt) and the cathode is heated to a predetermined temperature, whereby a group of electrons emitted from the cathode are accelerated and emitted as an electron beam 200.

[0038] 1 shows the configuration necessary for explaining the embodiment 1. The inspection device 100 may also include other configurations that are normally required.

[0039] FIG. 2 is a conceptual diagram showing the configuration of the shaping aperture array substrate in the first embodiment. In FIG. 2, the shaping aperture array substrate 203 has two-dimensional holes (apertures) 22 of m1 rows (x direction)×n1 columns (y direction) (m1 and n1 are integers of 2 or more) formed at a predetermined arrangement pitch in the x and y directions. The example of FIG. 2 shows a case where 23×23 holes (apertures) 22 are formed. Each hole 22 is formed as a rectangle of the same size and shape. Alternatively, they may be circles of the same outer diameter. A part of the electron beam 200 passes through each of the multiple holes 22, thereby forming multiple primary electron beams 20. The shaping aperture array substrate 203 is an example of a multi-beam forming mechanism that forms multiple primary electron beams.

[0040] The image acquiring mechanism 150 acquires an inspection image of the geometric pattern from the substrate 101 on which the geometric pattern is formed, using multiple electron beams. The operation of the image acquiring mechanism 150 in the inspection device 100 will be described below.

[0041] An electron beam 200 emitted from an electron gun 201 (emission source) is refracted by an electromagnetic lens 202 and illuminates the entire shaping aperture array substrate 203. A plurality of holes 22 (openings) are formed in the shaping aperture array substrate 203 as shown in Fig. 2, and the electron beam 200 illuminates an area including all of the plurality of holes 22. Each portion of the electron beam 200 irradiated to the positions of the plurality of holes 22 passes through each of the plurality of holes 22 in the shaping aperture array substrate 203, thereby forming multiple primary electron beams 20.

[0042] The formed multi-primary electron beam 20 is refracted by the electromagnetic lens 205 and the electromagnetic lens 206, respectively, and advances to the E×B separator 214 arranged at the height position of the intermediate image plane (image plane conjugate position: IIP) of each beam of the multi-primary electron beam 20 while repeating intermediate images and crossovers. Then, the multi-primary electron beam 20 passes through the E×B separator 214 and advances to the electromagnetic lenses 217 and 207. Also, by arranging a limiting aperture substrate 213 with a limited passing hole near the crossover position of the multi-primary electron beam 20, it is possible to block the scattered beam. Also, by deflecting the entire multi-primary electron beam 20 collectively by the collective deflector 212 and shielding the entire multi-primary electron beam 20 with the limiting aperture substrate 213, it is possible to blank the entire multi-primary electron beam 20.

[0043] When the multi-primary electron beams 20 are incident on the electromagnetic lenses 217, 207 (two-stage objective lenses), the electromagnetic lenses 217 refract the multi-primary electron beams 20, and the electromagnetic lenses 207 form an image of the multi-primary electron beams 20 on the substrate 101. In other words, the electromagnetic lenses 217, 207 irradiate the substrate 101 with the multi-primary electron beams 20. In further other words, the electromagnetic lenses 217, 207 guide the multi-primary electron beams 20 to the substrate 101. In this manner, the primary electron optical system 151 illuminates the substrate 101 with the multi-primary electron beams 20.

[0044] The multiple primary electron beams 20 focused on the surface of the substrate 101 (sample) by the electromagnetic lens 207 are deflected collectively by the deflector 208 and the deflector 209, and each beam is irradiated onto a respective irradiation position on the substrate 101. In this manner, the primary electron optical system 151 illuminates the substrate 101 with the multiple primary electron beams 20.

[0045] When the multiple primary electron beams 20 are irradiated onto a desired position on the substrate 101, a bunch of secondary electrons including reflected electrons (multiple secondary electron beams 300) is emitted from the substrate 101 due to the irradiation of the multiple primary electron beams 20. A secondary electron beam corresponding to each beam of the multiple primary electron beams 20 is emitted.

[0046] The multiple secondary electron beams 300 emitted from the substrate 101 pass through electromagnetic lenses 207 and 217 and proceed to the E×B separator 214 .

[0047] The E×B separator 214 (separator) separates the multiple secondary electron beams 300 emitted as a result of the substrate 101 being irradiated with the multiple primary electron beams 20 from the trajectory of the multiple primary electron beams 20 .

[0048] The E×B separator 214 has a plurality of magnetic poles (electromagnetic deflection coils) with four or more poles using coils, and a plurality of electrodes (electrostatic deflection electrodes) with four or more poles. For example, a plurality of magnetic poles with a phase shift of 90° and a plurality of electrodes with a phase shift of 90° are arranged. Also, a plurality of magnetic poles and a plurality of electrodes are arranged alternately with a phase shift of 45°. The arrangement is not limited to this. A plurality of magnetic poles and a plurality of electrodes may be arranged overlapping in the same phase. The E×B separator 214 deflects the multi-secondary electron beam 300 to generate a separating action. In the E×B separator 214, a directional magnetic field is generated by the plurality of magnetic poles. Similarly, a directional electric field is generated by the plurality of electrodes. Specifically, the E×B separator 214 generates an electric field E and a magnetic field B in a direction perpendicular to the direction in which the central beam of the multi-primary electron beam 20 advances (the central axis of the orbit). The electric field exerts a force in the same direction regardless of the traveling direction of the electrons. On the other hand, 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 the electrons' entry. The force FE due to the electric field and the force FB due to the magnetic field cancel each other out for the multiple primary electron beams 20 entering the E×B separator 214 from above, and the multiple primary electron beams 20 travel straight downward. On the other hand, the force FE due to the electric field and the force FB due to the magnetic field act in the same direction on the multiple secondary electron beams 300 entering the E×B separator 214 from below, and the multiple secondary electron beams 300 are deflected in a predetermined direction and bent obliquely upward, separating from the trajectory of the multiple primary electron beams 20.

[0049] The multiple secondary electron beams 300, which have been bent obliquely upward and separated from the multiple primary electron beams 20, are guided to the multi-detector 222 by the secondary electron optical system 152. Specifically, the multiple secondary electron beams 300, which have been separated from the multiple primary electron beams 20, are deflected by the deflector (bender) 218, and are further bent, and proceed to the electromagnetic lens 224. In other words, the deflector (bender) 218 ​​deflects the multiple secondary electron beams 300, which have been separated from the multiple primary electron beams 20, toward the multi-detector 222 (or detector 226).

[0050] Then, the multiple secondary electron beams 300 are projected onto the multi-detector 222 while being refracted in the focusing direction by the electromagnetic lens 224 at a position away from the trajectory of the multiple primary electron beams 20. In other words, the electromagnetic lens 224 disposed between the deflector 218 and the multi-detector 222 (or the detector 226) guides the multiple secondary electron beams 300 to the multi-detector 222 (or the detector 226).

[0051] The multi-detector 222 (multi-secondary electron beam detector) detects the multi-secondary electron beams 300 separated from the orbit of the multi-primary electron beams 20. In other words, the multi-detector 222 detects the refracted and projected multi-secondary electron beams 300. The multi-detector 222 has a plurality of detection elements (for example, a diode-type two-dimensional sensor, not shown). Then, each beam of the multi-primary electron beams 20 collides with a detection element corresponding to each secondary electron beam of the multi-secondary electron beams 300 on the detection surface of the multi-detector 222, generating electrons, and generating secondary electron image data for each pixel. The intensity signal detected by the multi-detector 222 is output to the detection circuit 106.

[0052] Fig. 3 is a diagram showing an example of a plurality of chip regions formed on a semiconductor substrate in the embodiment 1. In Fig. 3, a plurality of chips (wafer dies) 332 are formed in a two-dimensional array in an inspection region 330 of a substrate (semiconductor wafer) 101. A mask pattern for one chip formed on an exposure mask substrate is transferred onto each chip 332, reduced to, for example, 1 / 4, by an exposure device (stepper) not shown.

[0053] FIG. 4 is a diagram for explaining the image acquisition process in the first embodiment. As shown in FIG. 4, the area of ​​each chip 332 is divided into a plurality of stripe areas 32 with a predetermined width in the y direction, for example. The scanning operation by the image acquisition mechanism 150 is performed, for example, for each stripe area 32. For example, while moving the stage 105 in the -x direction, the scanning operation of the stripe area 32 is relatively advanced 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 collective deflection of the entire multi-primary electron beam 20 by two-stage deflectors 208, 209 (electrostatic deflectors).

[0054] In the example of FIG. 4, for example, a case of 5×5 arrays of multi-primary electron beams 20 is shown. An irradiation area 34 that can be irradiated by one irradiation of the multi-primary electron beams 20 is defined as (x-direction size obtained by multiplying the inter-beam pitch in the x direction of the multi-primary electron beams 20 on the substrate 101 surface by the number of beams in the x direction)×(y-direction size obtained by multiplying the inter-beam pitch in the y direction of the multi-primary electron beams 20 on the substrate 101 surface by the number of beams in the y direction). The irradiation area 34 becomes the field of view of the multi-primary electron beams 20. Then, each primary electron beam 10 constituting the multi-primary electron beam 20 is irradiated into a sub-irradiation area 29 surrounded by the inter-beam pitch in the x direction and the inter-beam pitch in the y direction in which the beam is located, and scans (scans) the sub-irradiation area 29. Each primary electron beam 10 is responsible for one of the mutually different sub-irradiation areas 29. Then, each primary electron beam 10 irradiates the same position in the assigned sub-irradiation area 29. The two-stage deflectors 208, 209 collectively deflect the multiple primary electron beams 20, thereby scanning the surface of the substrate 101 on which the pattern is formed with the multiple primary electron beams 20. In other words, the movement of the primary electron beam 10 within the sub-irradiation region 29 is performed by collective deflection of the entire multiple primary electron beams 20 by the two-stage deflectors 208, 209. By repeating this operation, one primary electron beam 10 is successively irradiated within one sub-irradiation region 29.

[0055] The width of each stripe region 32 is preferably set to the same size as the irradiation region 34 in the y direction, or narrower by a scan margin. In the example of FIG. 3, the irradiation region 34 is the same size as the rectangular region 33. However, this is not limited to the above. The irradiation region 34 may be smaller than the rectangular region 33. Alternatively, it may be larger than the rectangular region 33. Each primary electron beam 10 constituting the multiple primary electron beams 20 is irradiated into the sub-irradiation region 29 in which the beam is located, and scans (scans) the sub-irradiation region 29. When scanning of one sub-irradiation region 29 is completed, the irradiation position is moved to the adjacent rectangular region 33 in the same stripe region 32 by collective deflection of the entire multiple primary electron beams 20 by the two-stage deflectors 208 and 209. This operation is repeated to sequentially irradiate the stripe region 32. When scanning of one stripe region 32 is completed, the irradiation region 34 moves to the next stripe region 32 by moving the stage 105 or / and deflecting the entire multi-primary electron beam 20 by the two-stage deflectors 208, 209. As described above, scanning operation and acquisition of secondary electron images are performed for each sub-irradiation region 29 by 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 chip 332 is formed. In addition, when actually performing image comparison, the sub-irradiation region 29 in each rectangular region 33 is further divided into a plurality of frame regions 30, and frame images 31 that are measurement images for each frame region 30 are compared. The example of FIG. 4 shows a case where the sub-irradiation region 29 scanned by one primary electron beam 10 is divided into four frame regions 30 formed by dividing it into two in the x and y directions, for example.

[0056] Furthermore, when the substrate 101 is irradiated with the multiple primary electron beams 20 while the stage 105 is moving continuously, a tracking operation is performed by collective deflection by the two-stage deflectors 208 and 209 so that the irradiation position of the multiple primary electron beams 20 follows the movement of the stage 105. Therefore, the emission position of the multiple secondary electron beams 300 changes from moment to moment with respect to the central axis of the orbit of the multiple primary electron beams 20. Similarly, when scanning within the sub-irradiation region 29, the emission position of each secondary electron beam changes from moment to moment within the sub-irradiation region 29. The deflector 225 collectively deflects the multiple secondary electron beams 300 so that each secondary electron beam with its emission position changed is irradiated within the corresponding detection region of the multi-detector 222. In other words, the deflector 225 fixes the position of the multiple secondary electron beams 300 on the detection surface of the multi-detector 222, which changes due to scanning using the multiple primary electron beams 20, by deflecting back the multiple secondary electron beams. Thereby, each secondary electron beam can be detected by a corresponding detection element of the multi-detector 222. The deflector 225 is not limited to a single-stage deflector, and may be suitably configured as a two-stage deflector similar to the deflectors 208 and 209.

[0057] Here, as described above, the separated multiple secondary electron beams 300 are further deflected by the deflector 218 and then guided to the multi-detector 222. In order to capture an image of each secondary electron beam by the multi-detector 222, the multiple secondary electron beams 300 must be separated from one another on the detection surface of the multi-detector 222. For this purpose, it is required to form an intermediate image plane of the multiple secondary electron beams 300 at the center position (deflection fulcrum) of the deflector 218. The center position of the deflector 218 corresponds to a position at a distance of 1 / 2 the distance of the beam trajectory in the deflector 218, in other words, the intermediate position (center position) of the beam trajectory in the deflector 218. The imaging (formation of an intermediate image plane) of the multiple secondary electron beams 300 is performed by the electromagnetic lens 217 arranged on the trajectory before separation from the multiple primary electron beams 20.

[0058] By forming an image of the multiple secondary electron beams 300 at the center position of the deflector 218, it is possible to minimize the deflection aberration caused by the deflector 218. This makes it possible to separate the multiple secondary electron beams 300 from one another on the detection surface of the multi-detector 222.

[0059] 5 is a diagram for explaining an electron beam adjustment method in a comparative example of the first embodiment. In the comparative example, a detector 429 is placed near the outlet of the deflector (bender) 218. Then, the potential (input value) applied to the deflector (bender) 218 ​​is first set to a potential that can deflect the multiple secondary electron beams 300 in a direction in which they collide with the detector 429. Also, the input values ​​(excitation) of the electromagnetic lenses 217, 207 are set to initial values.

[0060] In the comparative example, the multiple primary electron beams 20 are narrowed down to one representative primary electron beam 21 by the beam selection aperture substrate 204. The representative primary electron beam 21 is then scanned over the mark 111 by the deflectors 208 and 209. The representative secondary electron beam 301 emitted from the mark 111 is then separated from the representative primary electron beam 21 by the E×B separator 214, and the separated representative secondary electron beam 301 is deflected by the deflector (bender) 218 ​​towards the detector 429. As a result, the detector 429 detects the mark image.

[0061] In the comparative example, first, the input value (excitation) of the electromagnetic lens 207 is adjusted so that the mark image is brought into focus.

[0062] Next, in the comparative example, the potential (input value) applied to the deflector (bender) 218 ​​is reset to a potential that deflects the multiple secondary electron beams 300 in a direction that causes them to collide with the detector 226. Then, the representative primary electron beam 21 is irradiated onto the mark 111. Here, scanning using the representative primary electron beam 21 by the deflectors 208 and 209 is not performed. Then, the representative secondary electron beam 301 emitted from the mark 111 is separated from the representative primary electron beam 21 by the E×B separator 214, and the deflector (bender) 218 ​​deflects the separated representative secondary electron beam 301 toward the detector 226. The deflected representative secondary electron beam 301 passes through the deflector 225 and the electromagnetic lens 224 and proceeds to the deflector 227. The deflector 227 scans the aperture substrate in front of the detector 226 with the representative secondary electron beam 301. As a result, the detector 226 detects an opening image of the aperture substrate. Then, the input value (excitation) of the electromagnetic lens 224 is adjusted so that the aperture image obtained by the detector 226 is in focus.

[0063] In the comparative example, the potential (input value) applied to the deflector (bender) 218 ​​is changed to check whether the position of the image obtained by the detector 226 changes, and if the position of the image moves, the input value (excitation) of the electromagnetic lens 217 is changed until the position of the image stops moving, and the above-mentioned operation is repeated for each input value of the electromagnetic lens 217.

[0064] In this way, in the comparative example, the above-mentioned operation is repeated while capturing the primary scan image by detector 429 and the secondary scan image by detector 226 separately at different times. In this way, it becomes necessary to obtain information on the primary electron beam and information on the secondary electron beam from images captured separately, which makes beam adjustment complicated.

[0065] Therefore, in the first embodiment, beam adjustment is performed while obtaining information on the primary electron beam and information on the secondary electron beam from the same image.

[0066] Fig. 6 is a block diagram showing an example of the configuration within the beam adjustment circuit in embodiment 1. In Fig. 6, within the beam adjustment circuit 134, a storage device 71 such as a magnetic disk device, a beam selection unit 60, a vendor input value setting unit 75, and a combination acquisition unit 80 are arranged. Arranged within the combination acquisition unit 80 are an input value 1 setting unit 62, an input value 2 setting unit 64, an input value 3 setting unit 66, a sharpness calculation unit 68, a determination unit 70, a sharpness calculation unit 72, a determination unit 74, a bender input value setting unit 76, a position change amount calculation unit 78, and a determination unit 79. Also arranged are a beam selection unit 60, a bender input value setting unit 75, and a combination acquisition unit 80. Each "unit" such as the beam selection unit 60, the bender input value setting unit 75, and the combination acquisition unit 80 (input value 1 setting unit 62, input value 2 setting unit 64, input value 3 setting unit 66, sharpness calculation unit 68, judgment unit 70, sharpness calculation unit 72, judgment unit 74, bender input value setting unit 76, position change amount calculation unit 78, and judgment unit 79) has a processing circuit. Such a processing circuit includes, for example, an electric circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Each "unit" may use a common processing circuit (the same processing circuit) or may use different processing circuits (separate processing circuits). Information input and output to the beam selection unit 60, bender input value setting unit 75, and combination acquisition unit 80 (input value 1 setting unit 62, input value 2 setting unit 64, input value 3 setting unit 66, sharpness calculation unit 68, judgment unit 70, sharpness calculation unit 72, judgment unit 74, bender input value setting unit 76, position change amount calculation unit 78, and judgment unit 79) and information being calculated are stored each time in memory 118 or a memory not shown in the beam adjustment circuit 134.

[0067] Fig. 7 is a flow chart showing an example of main steps of the multi-electron beam adjustment method in the embodiment 1. In Fig. 7, the multi-electron beam adjustment method in the embodiment 1 performs a series of steps including a beam selection step (S102), a vendor input value setting step (S104), a lens input value combination acquisition step (S105), a vendor input value return step (S142), a lenses 1 and 2 setting step (S152), a detector reconfiguration step (S154), and a lens 3 adjustment step (S156).

[0068] The lens input value combination acquisition process (S105) implements a series of internal processes, including a lens input value 1 setting process (S106), a lens input value 2 setting process (S108), a lens input value 3 setting process (S110), a scanning process (S112), a primary scan image sharpness calculation process (S114), a judgment process (S116), a secondary scan image sharpness calculation process (S120), a judgment process (S122), a vendor input value changing process (S130), a scanning process (S132), and a judgment process (S140).

[0069] First, instead of the multi-detector 222, a detector 226 is placed on the trajectory of the secondary electron beam. The detector 226 is placed on the trajectory of the secondary electron beam between the electromagnetic lens 224 and the multi-detector 222. Alternatively, the detector 226 is placed at the position where the multi-detector 222 is placed. Alternatively, the multi-detector 222 may be used as it is. When the multi-detector 222 is used, it is sufficient to use information from only one detection element.

[0070] In the beam selection step (S102), the beam selection unit 60 selects one representative primary electron beam 21 from the multiple primary electron beams 20. More specifically, the operation is as follows.

[0071] 8 is a top view showing an example of the beam selection aperture substrate in the first embodiment. In FIG. 8, the beam selection aperture substrate 204 is formed with a large aperture 11 through which the entire multi-primary electron beams 20 can pass, and a small aperture 13 through which one primary electron beam passes and which blocks the remaining primary electron beams. The beam selection unit 60 selects, for example, a central primary electron beam as a representative primary electron beam 21 from the multi-primary electron beams 20. The drive circuit 215 horizontally moves the beam selection aperture substrate 204 to a position where the selected representative primary electron beam 21 passes through the small aperture 13. As a result, of the entire multi-primary electron beams 20, the representative primary electron beam 21 passes through the small aperture 13 and the remaining primary electron beams are blocked. Thus, one representative primary electron beam 21 is selected from the multi-primary electron beams 20.

[0072] As a bender input value setting step (S104), the bender input value setting unit 75 sets an input value (electric potential) for deflecting the multiple secondary electron beams 300 toward the multiple detector 222 (here, the detector 226), and outputs the input value to the deflection control circuit 128. The deflection control circuit 128 controls the power supply 148, so that the power supply 148 applies the set electric potential to each electrode of the deflector 218.

[0073] As a lens input value combination acquisition step (S105), the combination acquisition unit 80 acquires a combination of a lens input value 1 (first focus input value) of the electromagnetic lens 217 (first lens) that focuses a representative secondary electron beam 301 (described later) at a middle position (predetermined position) of a deflector (bender) 218 ​​(first deflector), a lens input value 2 (second focus input value) of the electromagnetic lens 207 (second lens) that focuses the representative primary electron beam 21 on the substrate 101 or the mark 111, and a lens input value 3 (third focus input value) of the electromagnetic lens 224 (third lens) that focuses the representative secondary electron beam 301 on the multi-detector 222 (here, the detector 226) by using a secondary electron image for each combination of the input values ​​of the electromagnetic lenses 217, 207, and 224. Specifically, it operates as follows.

[0074] As a lens input value 1 setting step (S106), the input value 1 setting unit 62 sets a provisional input value 1 (excitation value 1) for exciting the electromagnetic lens 217 (objective lens 1). The provisional input value 1 is set to one of a plurality of values ​​including a predicted value obtained from past performance or simulation, etc. It is preferable to set a plurality of values ​​with the predicted value as a median value. The lens control circuit 124 excites the electromagnetic lens 217 with the provisional input value 1 that has been set. In other words, the lens control circuit 124 passes a current of the provisional input value 1 that has been set to the coil of the electromagnetic lens 217. In order to sequentially increase or decrease the input value 1, it is preferable here to set, for example, the smallest value of the plurality of values ​​(input value 1 with n=0) as the initial value.

[0075] As a lens input value 2 setting step (S108), the input value 2 setting unit 64 sets a provisional input value 2 (excitation value 2) for exciting the electromagnetic lens 207 (objective lens 2). The provisional input value 2 is set to one of a plurality of values ​​including a predicted value obtained from past performance or simulation, etc. It is preferable to set a plurality of values ​​with the predicted value as a median value. The lens control circuit 124 excites the electromagnetic lens 207 with the provisional input value 2 that has been set. In other words, the lens control circuit 124 passes a current of the provisional input value 2 that has been set to the coil of the electromagnetic lens 207. In order to sequentially increase or decrease the input value 2, it is preferable here to set, for example, the smallest value of the plurality of values ​​(input value 2 with n=0) as the initial value.

[0076] As the lens input value 3 setting step (S110), the input value 3 setting unit 66 sets a provisional input value 3 (excitation value 3) for exciting the electromagnetic lens 224 (objective lens 3). The provisional input value 3 is set to one of a plurality of values ​​including a predicted value obtained from past performance or simulation, etc. It is preferable to set a plurality of values ​​with the predicted value as a median value. The lens control circuit 124 excites the electromagnetic lens 224 with the provisional input value 3 that has been set. In other words, the lens control circuit 124 passes a current of the provisional input value 3 that has been set to the coil of the electromagnetic lens 224. In order to sequentially increase or decrease the input value 3, it is preferable here to set, for example, the smallest value of the plurality of values ​​(input value 3 with n=0) as the initial value.

[0077] In the scanning step (S112), the image acquisition mechanism 150 scans the substrate 101 or the mark 111 with the representative primary electron beam 21 for each combination of variable combinations of input values ​​of the electromagnetic lenses 217, 207, and the electromagnetic lens 224, scans the aperture substrate of the detector 226 with the representative secondary electron beam 301 emitted from the substrate 101 or the mark 111 by the scanning with the representative primary electron beam 21, detects the scanned representative secondary electron beam 301 with the detector 226, and acquires a secondary electron image based on the detected detection signal. The operation of the image acquisition mechanism 150 will be described below.

[0078] FIG. 9 is a diagram for explaining an example of an image acquisition method in the first embodiment. In the example of FIG. 9, a case where the mark 111 is scanned is shown. Instead of the mark 111, the substrate 101 may be used. In the first embodiment, when acquiring a secondary electron image for each combination of input values ​​of the electromagnetic lenses 217, 207, and 224, the representative primary electron beam 21 is used to scan the substrate 101 or the mark 111 using the deflectors 208 and 209 (second deflectors). Then, the representative secondary electron beam 301 emitted from the substrate 101 or the mark 111 is scanned on the aperture substrate of the detector 226 using the deflector (bender) 218 ​​(first deflector) and the multi-detector 222 (here, the detector 226).

[0079] In the example of FIG. 9, the representative primary electron beam 21 of the multiple primary electron beams 20 is scanned over the mark 111 while the lens action of the electromagnetic lens 217 is occurring due to the input value 1. The scanning of the mark 111 is performed by deflecting the representative primary electron beam 21 with the deflectors 208 and 209. With this scanning, a representative secondary electron beam 301 is emitted from the mark 111. The representative secondary electron beam 301 is subjected to the lens action of the electromagnetic lenses 207 and 217, and is separated from the orbit of the multiple primary electron beams 20 by the E×B separator 214. The separated representative secondary electron beam is bent by the deflector 218 and proceeds to the deflector 225. The deflector 225 fixes the position of the representative secondary electron beam 301 on the detection surface of the detector 226, which changes due to the scanning using the representative primary electron beam 21, by deflecting the representative secondary electron beam 301 back. Then, the representative secondary electron beam 301 that has been deflected back is projected onto the detector 226 by the electromagnetic lens 224. At that time, the deflector 227 scans the detector 226 with the representative secondary electron beam 301.

[0080] FIG. 10 is a top view of an example of a detector arranged in place of the multi-detector in the first embodiment. FIG. 11 is a cross-sectional view of an example of a detector arranged in place of the multi-detector in the first embodiment. In the examples of FIGS. 10 and 11, the detector 226 has an aperture substrate 14, a detection element 16, a plurality of support columns 17, and a base 18. One detection element 16 is arranged on the base 18. As the detection element 16, it is preferable to use an SSD that receives irradiation of an electron beam and converts it into an electric signal. An aperture substrate 14 having a plurality of openings 15 formed therein is arranged on the detection element 16. The aperture substrate 14 is supported on the base 18 by a plurality of support columns 17. The examples of FIGS. 10 and 11 show a case where 8×8 openings 15 are formed on the aperture substrate 14. Each opening 15 is formed, for example, in a rectangular shape.

[0081] Therefore, scanning the detector 226 with the representative secondary electron beam 301 is equivalent to scanning the aperture substrate 14 in which a plurality of openings 15 are formed with the representative secondary electron beam 301 .

[0082] Then, the representative secondary electron beam 301 that has been scanned and passed through the aperture 15 is detected by the detector 226. The detection data detected by the detector 226 is output, for example, to the detection circuit 106, which generates a secondary electron image. Alternatively, the data may be output to a detection circuit (not shown), which generates a secondary electron image. The generated secondary electron image is output to the beam adjustment circuit 134 and stored in the storage device 61.

[0083] Fig. 12 is a diagram showing an example of a secondary electron image in the first embodiment. As shown in Fig. 12, the secondary electron image shows both a pattern image obtained by scanning the substrate 101 or the mark 111 with the representative primary electron beam 21 and an aperture image obtained by scanning the aperture substrate 14 of the detector 226 with the representative secondary electron beam 301. Since a plurality of apertures 15 exist on one detection element 16, a plurality of aperture images are shown and a pattern image is shown in each aperture image. In the example of Fig. 12, the inner periphery of one aperture image is shown by a line for ease of viewing.

[0084] In this way, by scanning the substrate 101 or the mark 111 with the representative primary electron beam 21 and scanning the aperture substrate 14 of the detector 226 with the representative secondary electron beam 301, it is possible to capture the pattern image, which is the primary scan image, and the aperture image, which is the secondary scan image, together in the same image.

[0085] In the primary scan image sharpness calculation step (S114), the sharpness calculation unit 68 calculates the sharpness of the primary scan image.

[0086] Fig. 13 is a diagram showing an example of a focus adjustment method in embodiment 1. Fig. 13 shows an image intensity profile of the pattern of mark 111 detected in a defocused state (a state in which the imaging plane is shifted from the mark plane) and an image intensity profile of the pattern of mark 111 detected in a just-focused state (a state in which the imaging plane coincides with the mark plane). The sharpness calculation unit 68 calculates the width D of the rising portion of the image intensity profile pattern as the sharpness value. For example, the width D is calculated at positions of 30% and 70% of the maximum detected intensity. In a defocused state, the rising is gentle, and in a just-focused state, the rising is steep. The steeper the rising is, the smaller the width D of the rising portion becomes. The calculated sharpness value is stored in the storage device 61 in association with the secondary electron image.

[0087] In the determination step (S116), the determination unit 70 determines whether the primary scan image is in focus. Specifically, it determines whether the width D of the rising portion of the pattern of the image intensity profile of the primary scan image is equal to or smaller than the threshold value Th1, or is at a minimum. If the primary scan image is in focus, the process proceeds to the secondary scan image sharpness calculation step (S120). If the primary scan image is not in focus, the process returns to the lens input value 2 setting step (S108), and the value of the lens input value 2 is changed, and each step from the lens input value 2 setting step (S108) to the determination step (S116) is repeated until the primary scan image is in focus.

[0088] A process of determining the lens input value 2 (second focus input value) of the electromagnetic lens 207 (second lens) is performed by repeating each process from the lens input value 2 setting process (S108) to the determination process (S116) while changing the value of the lens input value 2 until the primary scan image is focused, so that the pattern image of the substrate 101 or the mark 111 is focused. For example, images are captured at a plurality of lens input values ​​2, and the width D of the rising portion of the pattern of the image intensity profile of the obtained primary scan image is plotted to search for the lens input value 2 that provides the minimum measured value.

[0089] This completes the adjustment of the lens input value 2 under the lens action of the electromagnetic lens 217 with the set lens input value 1. In other words, under the lens action of the electromagnetic lens 217 with the set lens input value 1, the lens control circuit 124 adjusts the lens input value 2 of the electromagnetic lens 207 so that the width D of the rising portion of the pattern of the image intensity profile is minimized.

[0090] In the secondary scan image sharpness calculation step (S120), the sharpness calculation unit 72 calculates the sharpness of the secondary scan image.

[0091] The sharpness calculation unit 72 calculates, as a sharpness value, the width D of the rising portion of the pattern of the image intensity profile of the aperture image, which is the secondary scan image obtained by scanning the aperture substrate 14 as shown in FIG. 12. For example, the width D is calculated at positions of 30% and 70% of the maximum detection intensity. As shown in FIG. 13, in a defocused state, the rising is gentle, and in a just-focused state, the rising is steep. The steeper the rising is, the smaller the width D of the rising portion becomes. The calculated sharpness value is stored in the storage device 61 in association with the secondary electron image.

[0092] In the determination step (S122), the determination unit 74 determines whether the secondary scan image is in focus. Specifically, it determines whether the width D of the rising portion of the pattern of the image intensity profile of the secondary scan image is equal to or smaller than the threshold value Th2, or is at a minimum. If the secondary scan image is in focus, the process proceeds to the bender input value change step (S130). If the secondary scan image is not in focus, the process returns to the lens input value 3 setting step (S110), the value of the lens input value 3 is changed, and each step from the lens input value 3 setting step (S110) to the determination step (S122) is repeated until the secondary scan image is in focus.

[0093] A process of determining the lens input value 3 (third focus input value) of the electromagnetic lens 224 (third lens) so that the aperture image is focused is performed by repeating the steps from the lens input value 3 setting step (S110) to the determination step (S122) while changing the value of the lens input value 3 until the secondary scan image is focused. For example, images are captured with a plurality of lens input values ​​3, and the width D of the rising portion of the pattern of the image intensity profile of the obtained secondary scan image is plotted to search for the lens input value 2 that provides the minimum measured value.

[0094] This completes the adjustment of the lens input value 3 under the lens action of the electromagnetic lens 217 with the set lens input value 1 and under the lens action of the electromagnetic lens 207 with the lens input value 2. In other words, under the lens action of the electromagnetic lens 217 with the set lens input value 1 and under the lens action of the electromagnetic lens 207 with the lens input value 2, the lens control circuit 124 adjusts the lens input value 3 of the electromagnetic lens 224 so that the width D of the rising portion of the pattern of the image intensity profile is minimized.

[0095] As a bender input value changing step (S130), the bender input value setting unit 76 changes the input value (electric potential) of the deflector 218 for deflecting the multiple secondary electron beams 300 toward the multiple detector 222 (here, the detector 226), and outputs it to the deflection control circuit 128. Here, the deflection angle of the deflector 218 is changed within a range in which the representative secondary electron beam 301 can be detected by the detector 226. The deflection control circuit 128 controls the power supply 148, which applies the set electric potential to each electrode of the deflector 218.

[0096] In the scanning process (S132), the image acquisition mechanism 150 scans the substrate 101 or the mark 111 with the representative primary electron beam 21 while the deflection angle of the deflector 218 is changed in a combination of input values ​​of the electromagnetic lenses 217, 207, and the electromagnetic lens 224, scans the aperture substrate of the detector 226 with the representative secondary electron beam 301 emitted from the substrate 101 or the mark 111 by the scanning with the representative primary electron beam 21, detects the scanned representative secondary electron beam 301 with the detector 226, and acquires a secondary electron image based on the detected detection signal.

[0097] In the determination step (S140), the position change amount calculation section 78 calculates the amount of change in the position of the aperture image from before to after the input value of the deflector 218 is changed. Next, the determination unit 79 determines whether the amount of position change of the aperture image is equal to or less than the threshold Th3 or is stationary. If the amount of position change is equal to or less than the threshold Th3 or is stationary, the process proceeds to the vendor input value return step (S142). If the amount of position change is equal to or less than the threshold Th3 or is not stationary, the process returns to the lens input value 1 setting step (S106), changes the value of the lens input value 1, and repeats each step from the lens input value 1 setting step (S106) to the determination step (S140) until the amount of position change is equal to or less than the threshold Th3 or is stationary.

[0098] A process of determining the lens input value 1 (first focus input value) of the electromagnetic lens 217 (first lens) is performed such that the amount of change in the position of the aperture image becomes equal to or less than a threshold value when the input value (fourth input value) of the deflector (bender) 218 ​​(first deflector) is changed by repeating each process from the lens input value 1 setting process (S106) to the judgment process (S140) while changing the value of the lens input value 1. For example, the primary scan image and the secondary scan image are focused with a plurality of lens input values ​​1, and a lens input value 1 is searched for where the amount of change in the position of the aperture image before and after changing the input value (electric potential) of the deflector 218 is equal to or less than a threshold value Th3, or where the lens input value 1 is fixed.

[0099] If the image does not move even if the input value is changed, the image plane is located at the deflection fulcrum. Therefore, with the primary scan image and the secondary scan image in focus, an intermediate image plane of the multiple secondary electron beams 300 has been formed at the center position (deflection fulcrum) of the deflector (bender) 218.

[0100] From the above, a combination is obtained of the lens input value 1 (first focus input value) of the electromagnetic lens 217 (first lens) that focuses the representative secondary electron beam 301 at the central position of the deflector (bender) 218 ​​and focuses the representative primary electron beam 21 on the substrate 101 or the mark 111, and the lens input value 2 (second focus input value) of the electromagnetic lens 207 (second lens), and the lens input value 3 (third focus input value) of the electromagnetic lens 224 (third lens) that focuses the representative secondary electron beam 301 on the multi-detector 222 (here, detector 226). For example, a combination is acquired of a lens input value 1 (first focus input value) of the electromagnetic lens 217 (first lens) that focuses the representative secondary electron beam 301 at the middle position of the deflector (bender) 218, a lens input value 2 (second focus input value) of the electromagnetic lens 207 (second lens) that focuses the representative primary electron beam 21 on the substrate 101 or the mark 111, and a lens input value 3 (third focus input value) of the electromagnetic lens 224 (third lens) that focuses the representative secondary electron beam 301 on the multi-detector 222 (here, the detector 226). Information on the acquired combination is output to the lens control circuit 124.

[0101] In a bender input value returning step (S142), the bender input value setting unit 76 returns the changed input value of the deflector 218 to the original input value (electric potential) set in the bender input value setting step (S104), and outputs it to the deflection control circuit 128. Here, the deflection angle of the deflector 218 is changed within a range in which the representative secondary electron beam 301 can be detected by the detector 226. The deflection control circuit 128 controls the power supply 148, which applies the set electric potential to each electrode of the deflector 218.

[0102] As a lens 1, 2 setting step (S152), the lens control circuit 124 sets the lens input value 1 (first focus input value) of the acquired combination to the electromagnetic lens 217, and sets the lens input value 2 (second focus input value) of the acquired combination to the electromagnetic lens 207.

[0103] In the detector rearrangement step (S154), the detector 226 is removed and the multi-detector 222 is installed. In addition, the beam selection aperture substrate 204 is moved so that the entire multi-primary electron beams 20 pass through the large aperture 11.

[0104] In the lens 3 adjustment step (S156), in a state where the lens input values ​​1 and 2 of the determined combination are set to the electromagnetic lenses 217 and 207, respectively, the electromagnetic lens 224 is used to guide the multiple secondary electron beams 300 emitted due to the irradiation of the substrate 101 or the mark 111 with the multiple primary electron beams 20 to the multi-detector 222. Specifically, the multiple secondary electron beams 300 are scanned over the detector aperture array board 223 arranged in front of the multi-detector 222. Each detection element of the multi-detector 222 detects the secondary electron beam that has passed through the corresponding opening of the detector aperture array board 223. Since multiple secondary electron beams pass over the opening depending on the scan range, a secondary electron image of multiple aperture images in an array is obtained at each detection element. The lens input value 3 of the electromagnetic lens 224 is adjusted so that each detection element of the multi-detector 222 can detect multiple aperture images in an array. If each detection element can detect a plurality of array-like aperture images, it means that the multiple secondary electron beams 300 can be separated on the detection surface of the multi-detector 222. Then, the lens input value 3 of the electromagnetic lens 224 is adjusted so that the rise width D of the intensity profile of the aperture image in the secondary electron image obtained by each detection element is minimized (the rise becomes steep). This makes it possible for the electromagnetic lens 224 to guide the multiple secondary electron beams 300 so that information on the multiple secondary electron beams 300 can be obtained by the multi-detector 222.

[0105] FIG. 14 is a diagram for explaining an example of an image acquisition method in the first modification of the first embodiment. The example of FIG. 14 shows a case where the mark 111 is scanned. The substrate 101 may be used instead of the mark 111. In the example of FIG. 9, the representative secondary electron beam 301 is scanned on the detector 226 by the deflector 227, but the present invention is not limited to this. In the first modification of the first embodiment, when acquiring a secondary electron image for each combination of input values ​​of the electromagnetic lenses 217, 207, and 224, the representative primary electron beam 21 is scanned on the substrate 101 or the mark 111 by using the deflectors 208 and 209 (second deflectors). Then, the aperture substrate 14 is scanned with the representative secondary electron beam 301 emitted from the substrate 101 or the mark 111 using a deflector 225 (another example of a third deflector) disposed between the deflector (bender) 218 ​​(first deflector) and the multi-detector 222 (detector 226 in this case). In other words, the detector 226 is scanned with the representative secondary electron beam 301 by the deflector 225 without using the deflector 227.

[0106] The deflector 225, for example, deflects the representative secondary electron beam 301 with a deflection amount obtained by adding a deflection amount for scanning the detector 226 with the representative secondary electron beam 301 to a deflection amount for a return deflection that fixes the position of the representative secondary electron beam 301 on the detection surface of the detector 226, which position changes due to scanning with the representative primary electron beam 21. This makes it possible to obtain a secondary electron image as shown in Fig. 12. In other words, it is possible to obtain a secondary electron image in which both a pattern image obtained by scanning the substrate 101 or the mark 111 with the representative primary electron beam 21 and an aperture image obtained by scanning the aperture substrate 14 of the detector 226 with the representative secondary electron beam 301 are shown together.

[0107] FIG. 15 is a diagram for explaining an example of an image acquisition method in the second modification of the first embodiment. In the example of FIG. 15, the mark 111 is scanned. The substrate 101 may be used instead of the mark 111. In the examples of FIG. 9 and FIG. 14, the representative secondary electron beam 301 is scanned on the detector 226 by the deflector 225 or the deflector 227 of the secondary electron optical system 152, but the present invention is not limited to this. In the second modification of the first embodiment, when acquiring a secondary electron image for each combination of input values ​​of the electromagnetic lenses 217, 207, and 224, the representative primary electron beam 21 is scanned on the substrate 101 or the mark 111 using the deflectors 208 and 209 (second deflectors), and the representative secondary electron beam 301 emitted from the substrate 101 or the mark 111 is scanned on the aperture substrate 14. In other words, the representative secondary electron beam 301 is scanned over the detector 226 by the deflectors 208 and 209 without using the deflectors 225 and 227. Here, the case where the two-stage deflectors 208 and 209 are used has been described, but the representative primary electron beam 21 may be deflected by the one-stage deflector 208 (or 209).

[0108] Here, since no deflection is performed by the deflector 225, for example, the position of the representative secondary electron beam 301 on the detection surface of the detector 226 fluctuates due to scanning using the representative primary electron beam 21. Due to such fluctuation, the aperture substrate 14 of the detector 226 is scanned. Even in such a case, a secondary electron image such as that shown in Fig. 12 can be acquired. In other words, a secondary electron image can be acquired in which both a pattern image obtained by scanning the substrate 101 or the mark 111 with the representative primary electron beam 21 and an aperture image obtained by scanning the aperture substrate 14 of the detector 226 with the representative secondary electron beam 301 are captured together.

[0109] Fig. 16 is a diagram for explaining an example of an image acquisition method in the third modification of the first embodiment. The example of Fig. 16 shows a case where the mark 111 is scanned. The substrate 101 may be used instead of the mark 111. In the above-mentioned configurations, the case where the multi-detector 222 is transferred to the detector 226 and then the beam adjustment is performed has been described, but the present invention is not limited to this. The beam adjustment may be performed by using the multi-detector 222 as it is.

[0110] FIG. 17 is a top view showing an example of a detector aperture array substrate in the first embodiment. FIG. 18 is a cross-sectional view showing an example of the multi-detector in the first embodiment. As shown in FIG. 18, the multi-detector 222 has a plurality of detection elements 42 arranged in an array (grid). As shown in FIG. 17 and FIG. 18, a plurality of openings 45 are formed in the detector aperture array substrate 223 at the arrangement pitch of the plurality of detection elements 42 (detection elements). The example of FIG. 17 shows a case where 5×5 openings 45 are formed. The example of FIG. 17 shows a case where the opening 15 is formed in a rectangular shape. In this case, 5×5 detection elements 42 are arranged in the multi-detector 222. The plurality of detection elements 42 are arranged on a base 44. The detector aperture array substrate 223 is supported on the plurality of detection elements 42 by a plurality of support columns 43 extending from the base 44.

[0111] FIG. 19 is a diagram showing an example of a secondary electron image in the third modification of the first embodiment. FIG. 20 is a diagram showing another example of a secondary electron image in the third modification of the first embodiment. Unlike the detector 226, one corresponding aperture 45 is arranged on each detection element 42 of the multi-detector 222. Therefore, one aperture image 46 is captured in the obtained secondary electron image. Therefore, depending on the size of the scan range of the primary scan, it may occur that only one edge of both edges of the pattern image 47 is captured as shown in FIG. 19. In that case, by increasing the size of the scan range of the primary scan, both edges of the pattern image 47 can be captured in the aperture image 46 as shown in FIG. 20. However, increasing the size of the scan range of the primary scan reduces the image resolution. Furthermore, depending on the size of the scan range of the secondary scan, when the input value of the deflector (bender) 218 ​​is changed, the position of the aperture image may fluctuate, and the frame of the aperture image may extend beyond the secondary electron image.

[0112] In contrast, in the case of detector 226 in which multiple apertures 15 are formed on one detection element 16, multiple aperture images are captured in the obtained secondary electron image. Therefore, the probability that an aperture image exists in which both edges of a pattern image are captured inside can be increased significantly. Furthermore, when the input value of deflector (bender) 218 ​​is changed, it is possible to prevent the frames of all aperture images from going out of the secondary electron image even if the positions of the aperture images change. Therefore, although beam adjustment is possible with modification 3, it is more desirable to place detector 226 instead of multi-detector 222.

[0113] As described above, the electromagnetic lenses 217 and 207 (and the electromagnetic lens 224) are adjusted by the method for adjusting the multi-electron beam. Then, the inspection device 100 equipped with the electromagnetic lenses 217 and 207 and the electromagnetic lens 224 adjusted by the method for adjusting the multi-electron beam is used to perform the inspection process.

[0114] In the inspection process, as described above, the image acquisition mechanism 150 performs a scan 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 deflected by the deflector 218, and is then detected by the multi detector 222. The detected multi secondary electron beam 300 may include reflected electrons. Alternatively, the reflected electrons may diverge while moving through the secondary electron optical system and may not reach the multi detector 222. Then, a secondary electron image based on the signal of the detected multi secondary electron beam 300 is acquired. Specifically, the detection data of the secondary electrons (measurement image data: secondary electron image data: inspected image data) for each pixel in 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 to digital data by an A / D converter (not shown) and stored in the chip pattern memory 123. The obtained measurement image data is then transferred to the comparison circuit 108 together with information indicating each position from the position circuit 107.

[0115] FIG. 21 is a configuration diagram showing an example of the configuration in the comparison circuit in the first embodiment. In FIG. 21, the comparison circuit 108 includes storage devices 50, 52, 56 such as a magnetic disk device, a frame image creation unit 54, a positioning unit 57, and a comparison unit 58. Each "unit" such as the frame image creation unit 54, the positioning 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. In addition, each "unit" may use a common processing circuit (the same processing circuit). Alternatively, different processing circuits (separate processing circuits) may be used. Input data or calculation results required for the frame image creation unit 54, the positioning unit 57, and the comparison unit 58 are stored in a memory (not shown) or memory 118 each time.

[0116] The measured image data (beam image) transferred to the comparison circuit 108 is stored in the storage device 50.

[0117] Then, the frame image creation unit 54 creates a frame image 31 for each of a 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. The frame regions 30 are used as unit regions of the inspection image. It is preferable that each frame region 30 is configured so that the margin regions overlap each other to prevent any missing image. The created frame images 31 are stored in the storage device 56.

[0118] On the other hand, the reference image creation circuit 112 creates a reference image corresponding to the frame image 31 for each frame area 30 based on the design data that is the basis of the multiple graphic patterns formed on the substrate 101. Specifically, it operates as follows: First, it reads out the design pattern data from the storage device 109 through the control computer 110, and converts each graphic pattern defined in the read out design pattern data into binary or multi-value image data.

[0119] As described above, the figures defined in the design pattern data are based on basic figures such as rectangles and triangles, and the figure data stored defines the shape, size, position, etc. of each pattern figure using information such as the coordinates (x, y) at the reference position of the figure, the length of the sides, and a figure code that serves as an identifier to distinguish the type of figure, such as a rectangle or triangle.

[0120] When the design pattern data that constitutes such graphic data is input to the reference image creation circuit 112, it is expanded into data for each graphic, and the graphic code indicating the graphic shape of the graphic data, the graphic dimensions, etc. are interpreted. The circuit then expands the data into binary or multi-value design pattern image data as a pattern to be placed within a grid having a predetermined quantized dimension as a unit, and outputs the data. In other words, the design data is read, the inspection area is virtually divided into grids having a predetermined dimension as a unit, the occupancy rate of the graphic in the design pattern is calculated for each grid, and n-bit occupancy data is output. For example, it is preferable to set one grid as one pixel. Then, 1 / 2 pixel is assigned to one pixel. 8 If the resolution is to be 1 / 256, a small area of ​​1 / 256 is allocated for the area of ​​the figure placed in the pixel, and the occupancy rate within the pixel is calculated. This results in 8-bit occupancy data. This grid (inspection pixel) can be aligned with the pixels of the measurement data.

[0121] Next, the reference image creation circuit 112 applies a filter process to the design image data of the design pattern, which is image data of the graphic, using a predetermined filter function. This makes it possible to match the design image data, which is image data on the design side with image intensity (grayscale value) being a digital value, to the image generation characteristics obtained by irradiation with the multiple primary electron beams 20. The image data for each pixel of the created reference image is output to the comparison circuit 108. The reference image data transferred to the comparison circuit 108 is stored in the storage device 52.

[0122] Next, the alignment unit 57 reads out the frame image 31 to be 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 alignment may be performed using the least squares method.

[0123] 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 with the reference image for each pixel. The comparison unit 58 compares the two for each pixel according to a predetermined judgment condition, and judges the presence or absence of a defect such as a shape defect. For example, if the gradation value difference for each pixel is greater than the judgment threshold value Th, it is judged to be a defect. Then, the comparison result is output. The comparison result may be output to the storage device 109 or memory 118, or may be output from the printer 119.

[0124] In addition to the above-mentioned die-to-database inspection, it is also preferable to perform a die-to-die inspection in which measurement image data obtained by capturing the same pattern at different locations on the same substrate are compared. Alternatively, inspection may be performed using only the own measurement image.

[0125] As described above, according to the first embodiment, the multiple primary electron beams 20 can be focused on the substrate to be inspected, and the electromagnetic lens 217 upstream of the deflector (bender) 218 ​​can be adjusted so as to form an intermediate image plane of the multiple secondary electron beams 300 near the center position of the deflector (bender) 218 ​​on the trajectory of the multiple secondary electron beams 300 separated from the trajectory of the multiple primary electron beams 20.

[0126] Embodiment 2 In the above-mentioned first embodiment, the case where only one representative primary electron beam 21 of the multiple primary electron beams 20 is used to scan the substrate 101 or the mark 111 has been described, but the present invention is not limited to this. In the second embodiment, a configuration in which the substrate 101 or the mark 111 is scanned using the multiple primary electron beams 20 will be described. The contents other than those specifically described below may be the same as those in the first embodiment.

[0127] The configuration of the inspection device 100 in the second embodiment may be the same as that in Fig. 1. In the second embodiment, since the multiple primary electron beams 20 are not narrowed down to the representative primary electron beam 21, the beam selection aperture board 204 and the drive circuit 215 in Fig. 1 may be omitted. In addition, the configuration of the beam adjustment circuit 134 in the second embodiment may be the same as that in Fig. 6. In addition, in the second embodiment, since the multiple primary electron beams 20 are not narrowed down to the representative primary electron beam 21, the beam selection unit 60 in Fig. 6 may be omitted.

[0128] Fig. 22 is a flowchart showing an example of main steps of the multi-electron beam adjustment method in the embodiment 2. The flowchart shown in Fig. 22 is the same as Fig. 7 except that the beam selection step (S102) and the detector rearrangement step (S154) are omitted.

[0129] First, in the second embodiment, the multi-detector 222 is used as is without using the detector 226. As shown in Fig. 17 and Fig. 18, the multi-detector 222 has a detector aperture array substrate 223 on which a plurality of openings 45 are formed, and which is arranged above a plurality of detection elements 42 so that a different opening 45 is located above each detection element 42.

[0130] The contents of the vendor input value setting step (S104) are the same as those of embodiment 1. Of the lens input value combination acquisition step (S105), the contents of the lens input value 1 setting step (S106), the lens input value 2 setting step (S108), and the lens input value 3 setting step (S110) are the same as those of embodiment 1.

[0131] In the scanning step (S112), the image acquisition mechanism 150 scans the substrate 101 or the mark 111 with the multi primary electron beams 20 for each combination of variable combinations of input values ​​of the electromagnetic lenses 217, 207, and the electromagnetic lens 224, scans the aperture substrate of the multi detector 222 with the multi secondary electron beams 300 emitted from the substrate 101 or the mark 111 by the scanning with the multi primary electron beams 20, detects the scanned multi secondary electron beams 300 with the multi detector 222, and acquires a secondary electron image based on the detected detection signal. The operation of the image acquisition mechanism 150 will be described below.

[0132] FIG. 23 is a diagram for explaining an example of an image acquiring method in the second embodiment. FIG. 23 shows a case where the mark 111 is scanned. The substrate 101 may be used instead of the mark 111. FIG. 23 also shows an example of a trajectory of the representative primary electron beam 21 of the multiple primary electron beams 20, and an example of a trajectory of the representative secondary electron beam 301 of the multiple secondary electron beams 300. In the second embodiment, when acquiring a secondary electron image for each combination of input values ​​of the electromagnetic lenses 217, 207, and 224, the substrate 101 or the mark 111 is scanned with the multiple primary electron beam 20 using the deflectors 208 and 209 (second deflectors). Then, a deflector 227 (an example of a third deflector) arranged between the deflector (bender) 218 ​​(first deflector) and the multi-detector 222 is used to scan the aperture substrate of the detector 226 with the multi-secondary electron beam 300 emitted from the substrate 101 or the mark 111.

[0133] In the example of FIG. 23, similarly to the first embodiment, the mark 111 is scanned with the multi primary electron beams 20 in a state where the lens action of the electromagnetic lens 217 is occurring due to the input value 1. The scanning of the mark 111 is performed by deflecting the multi primary electron beams 20 with the deflectors 208 and 209. With this scanning, the multi secondary electron beams 300 are emitted from the mark 111. The multi secondary electron beams 300 are subjected to the lens action of the electromagnetic lenses 207 and 217, and are separated from the trajectory of the multi primary electron beams 20 by the E×B separator 214. The separated multi secondary electron beams 300 are bent by the deflector 218 and proceed to the deflector 225. The deflector 225 fixes the position of the multi secondary electron beams 300 on the detection surface of the multi detector 222, which changes due to the scanning using the multi primary electron beams 20, by deflecting the multi secondary electron beams 300 back. Then, the deflected multiple secondary electron beams 300 are projected onto the multi-detector 222 by the electromagnetic lens 224. At this time, the deflector 227 scans the multi-detector 222 with the multiple secondary electron beams 300. When the detector aperture array substrate 223 is scanned with the multiple secondary electron beams 300 emitted from the substrate 101 or the mark 111, the multi-detector 222 detects the multiple secondary electron beams 222 so that two or more secondary electron beams do not enter one opening 45 in the multi-detector 222.

[0134] FIG. 24 is a diagram showing the relationship between the detector aperture array substrate and the multiple secondary electron beams in the second embodiment. The size S of the multiple openings 45 of the detector aperture array substrate 223 of the multi-detector 222 is formed to be smaller than the beam pitch P of the multiple secondary electron beams 300 on the multi-detector 222 (on the detector aperture array substrate 223). When the size and beam pitch of the openings 45 are different in the x direction and the y direction, the size Sx of the openings 45 in the x direction is formed to be smaller than the beam pitch Px of the multiple secondary electron beams 300 in the same direction, and the size Sy of the openings 45 in the y direction is formed to be smaller than the beam pitch Py of the multiple secondary electron beams 300 in the same direction. This makes it possible to make each opening 45 detect only one secondary electron beam even if the detector aperture array substrate 223 is scanned with the multiple secondary electron beams 300. In other words, it is possible to make it possible to prevent two or more beams from being detected at the same time. The scan width is set to a range larger than the size S of the openings 45 (Sx in the x direction, Sy in the y direction). This allows an aperture image to be obtained. The scan width may be larger than the beam pitch P of the multiple secondary electron beams 300. Since a time lag occurs during detection between the information of the target secondary electron beam and the information of the other secondary electron beams, the information of two or more secondary electron beams can be separated for each detection element without being mixed.

[0135] 25 is a diagram showing an example of particles in embodiment 2. In embodiment 2, it is preferable to use a plurality of metal particles having random shapes, sizes, and arrangement positions for mark 111. By using a plurality of metal particles having random shapes, sizes, and arrangement positions, focusing can be facilitated.

[0136] FIG. 26 is a diagram showing an example of a secondary electron image in the second embodiment. In the example of FIG. 26, an example of an image of a mark 111 in which a plurality of metal particles having random shapes, sizes, and arrangement positions are arranged is shown. An image is obtained for each detection element. In other words, an image is obtained for each beam of the multi-secondary electron beam 300. If the position of the multi-secondary electron beam 300 is significantly shifted by scanning, the beam is not incident on at least some detection elements, and therefore a set of a pattern image and an aperture image is not obtained. Therefore, the multiple secondary electron images at the time when all images of the multi-secondary electron beam 300 are obtained are multiple secondary electron images when each secondary electron beam is detected by the corresponding detection element. The frame of each image indicates the aperture image obtained by scanning with the secondary electrons. The image within the frame of each image indicates the pattern image obtained by scanning with the primary electrons.

[0137] The contents of each of the steps within the lens input value combination acquisition step (S105), namely the primary scan image sharpness calculation step (S114), the judgment step (S116), the secondary scan image sharpness calculation step (S120), the judgment step (S122), the vendor input value change step (S130), the scanning step (S132), and the judgment step (S140), are the same as those in embodiment 1. In addition, in the primary scan image sharpness calculation step (S114), the judgment step (S116), the secondary scan image sharpness calculation step (S120), and the judgment step (S122), it is not necessary to use the secondary electron images of all detection elements; for example, it is sufficient to use the secondary electron image obtained by the detection element that detected the central secondary electron beam.

[0138] Moreover, in the determination step (S140), if the amount of change in the position of the aperture image is equal to or smaller than the threshold value Th3 or is stationary, the process proceeds to a bender input value returning step (S142).

[0139] As a result, a combination is acquired of the lens input value 1 (first focus input value) of the electromagnetic lens 217 (first lens) that focuses the multiple secondary electron beams 300 at the center position of the deflector (bender) 218 ​​and the lens input value 2 (second focus input value) of the electromagnetic lens 207 (second lens) that focuses the multiple primary electron beams 20 on the substrate 101 or the mark 111, and the lens input value 3 (third focus input value) of the electromagnetic lens 224 (third lens) that focuses the multiple secondary electron beams 300 on the multi-detector 222. Information on the acquired combination is output to the lens control circuit 124.

[0140] The contents of each of the vendor input value return step (S142), lens 1, 2 setting step (S152), and lens 3 adjustment step (S156) are the same as those in embodiment 1. Note that in embodiment 2, in the lens 3 adjustment step (S156), since the detectors are not rearranged, the lens input value 3 of the acquired combination can be set to the electromagnetic lens 224 (third lens).

[0141] 14 can be applied to the second embodiment. In this case, in the first modification of the second embodiment, when acquiring a secondary electron image for each combination of input values ​​of the electromagnetic lenses 217, 207, and 224, the multi primary electron beams 20 are used to scan the substrate 101 or the mark 111 using the deflectors 208 and 209 (second deflectors). Then, the detector aperture array substrate 223 of the multi detector 222 is scanned with the multi secondary electron beams 300 emitted from the substrate 101 or the mark 111 using the deflector (bender) 218 ​​(first deflector) and the multi detector 222 (another example of the third deflector).

[0142] 15 can be applied to the second embodiment. In this case, in the second modification of the second embodiment, when acquiring a secondary electron image for each combination of input values ​​of the electromagnetic lenses 217, 207, and 224, the multi primary electron beams 20 are scanned over the substrate 101 or the mark 111 using the deflectors 208 and 209 (second deflectors), and the multi secondary electron beams 300 emitted from the substrate 101 or the mark 111 are scanned over the aperture substrate 14. In other words, the multi secondary electron beams 300 are scanned over the multi detector 222 by the deflectors 208 and 209 without using the deflectors 225 and 227.

[0143] Here, since no deflection back is performed by the deflector 225, for example, the position of the multiple secondary electron beams 300 on the detection surface of the multi-detector 222 fluctuates due to scanning using the multiple primary electron beams 20. Due to such fluctuation, the detector aperture array substrate 223 of the multi-detector 222 is scanned.

[0144] As described above, according to the second embodiment, even when scanning is performed using multiple beams, the multiple primary electron beams 20 can be focused on the substrate to be inspected, and the electromagnetic lens 217 upstream of the deflector (bender) 218 ​​can be adjusted so as to form an intermediate image plane of the multiple secondary electron beams 300 near the center position of the deflector (bender) 218 ​​on the trajectory of the multiple secondary electron beams 300 separated from the trajectory of the multiple primary electron beams 20. Moreover, by making an adjustment using the inspection multi-detector 222, the electromagnetic lens 224 downstream of the deflector (bender) 218 ​​can also be adjusted.

[0145] In the above description, a series of "circuits" includes a processing circuit, which may include an electric circuit, a computer, a processor, a circuit board, a quantum circuit, or a semiconductor device. Each "circuit" may use a common processing circuit (the same processing circuit). Alternatively, different processing circuits (separate processing circuits) may be used. A program for executing the processor may be recorded on a recording medium such as a magnetic disk device, a magnetic tape device, a FD, or a ROM (read-only memory). For example, the position circuit 107, the comparison circuit 108, the reference image creation circuit 112, the stage control circuit 114, the lens control circuit 124, the blanking control circuit 126, the deflection control circuit 128, the retarding control circuit 130, the E×B separator control circuit 132, and the beam adjustment circuit 134 may be composed of at least one of the above-mentioned processing circuits.

[0146] Although the embodiments have been described above with reference to specific examples, the present invention is not limited to these specific examples.

[0147] Further, although the description of the device configuration, control method, and other parts not directly necessary for the explanation of the present invention have been omitted, the required device configuration and control method can be appropriately selected and used.

[0148] In addition, all other multi-electron beam adjustment methods and multi-electron beam inspection apparatuses that include the elements of the present invention and that can be appropriately modified by those skilled in the art are included within the scope of the present invention. [Explanation of symbols]

[0149] 10 Primary electron beam 11 Large Opening 13 Small opening 14 Aperture Board 15 Opening 16 Detector element 17 Posts 18 Foundation 20 Multi-primary electron beam 21 Representative primary electron beam 22 holes 29 Sub-irradiation area 30 Frame Area 31 Frame Images 32 Stripe Area 33 Rectangular area 34 Irradiation area 42 Detection element 43 Post 44 Foundation 45 Opening 46 Aperture image 47 Pattern Image 60 Beam selection section 62 Input value 1 setting section 64 Input value 2 setting section 66 Input value 3 setting section 68 Sharpness calculation section 70 Judgment section 71 Storage device 72 Sharpness calculation section 74 Judgment section 75 Vendor input value setting section 76 Vendor input value setting section 78 Position change amount calculation unit 79 Judgment section 80 Combination Acquisition Unit 100 Inspection Equipment 101 Substrate 102 Electron Beam Column 103 Examination Room 105 Stages 106 Detection circuit 107 Position circuit 108 Comparison circuit 109 Storage 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 134 Beam Adjustment Circuit 142 Stage drive mechanism 144,146,147,149 DAC Amplifiers 148 Power supply 150 Image Acquisition Mechanism 151 Primary electron optical system 152 Secondary electron optical system 160 Control Circuits 200 Electron Beam 201 Electron Gun 202, 205, 217, 207 Electromagnetic lenses 203 Shaped aperture array substrate 204 Beam selection aperture board 208 Deflector 209 Deflector 212 Bulk deflector 213 Limiting Aperture Substrate 214 E×B separator 215 Drive circuit 216 Mirror 218 Deflector 222 Multi-detector 223 Detector aperture array substrate 224 Electromagnetic Lens 225 Deflector 226 Detector 227 Deflector 300 Multi-Secondary Electron Beam 301 Representative secondary electron beam 330 Inspection Area 332 Chips

Claims

1. a separator for separating multiple secondary electron beams emitted due to irradiation of a substrate or a mark with the multiple primary electron beams from the multiple primary electron beams; first and second lenses disposed between the separator and the substrate to direct the multiple primary electron beams to the substrate; a first deflector that deflects the multiple secondary electron beams separated from the multiple primary electron beams by the separator toward a detector having an aperture substrate with openings disposed on a detection element; a third lens disposed between the first deflector and the detector, the third lens directing the multiple secondary electron beams to the detector; A method for adjusting multiple electron beams of a multiple electron beam image acquisition apparatus, comprising: selecting one representative primary electron beam from the multiple primary electron beams; a step of acquiring a secondary electron image in which both a pattern image obtained by scanning the substrate or mark with the representative primary electron beam and an aperture image obtained by scanning the aperture substrate with the representative secondary electron beam are captured together, by scanning the substrate or mark with the representative primary electron beam for each combination of variable input values ​​to the first, second, and third lenses, scanning the substrate or mark with a representative secondary electron beam emitted from the substrate or mark by scanning with the representative primary electron beam, and detecting the scanned representative secondary electron beam with the detector; a step of acquiring a combination of a first focus input value of the first lens, which is disposed on the separator side among the first and second lenses, for focusing the representative secondary electron beam on a predetermined position of the first deflector, a second focus input value of the second lens for focusing the representative primary electron beam on the substrate or the mark, and a third focus input value of the third lens for focusing the representative secondary electron beam on the detector, using a secondary electron image for each combination of input values ​​to the first, second, and third lenses; setting a first focus input value of the obtained combination to the first lens and setting a second focus input value of the obtained combination to the second lens; A method for adjusting multiple electron beams, comprising:

2. 2. The method for adjusting a multi-electron beam according to claim 1, wherein, when acquiring a secondary electron image for each combination of input values ​​of the first, second and third lenses, a second deflector arranged between the separator and the substrate is used to scan the substrate or mark with the representative primary electron beam and to scan the aperture substrate with the representative secondary electron beam emitted from the substrate.

3. 2. The method for adjusting a multi-electron beam according to claim 1, wherein, when acquiring a secondary electron image for each combination of input values ​​of the first, second and third lenses, the representative primary electron beam is used to scan the substrate or the mark using a second deflector arranged between the separator and the substrate, and the representative secondary electron beam emitted from the substrate is used to scan the aperture substrate using a third deflector arranged between the first deflector and the detector.

4. The step of obtaining the combination includes: determining the second focus input value of the second lens so that the pattern image is in focus; determining the third focus input value of the third lens such that the aperture image is in focus; determining the first focus input value of the first lens such that a position change amount of the aperture image becomes equal to or smaller than a threshold value when a fourth input value of the first deflector is changed; 4. The method for adjusting multiple electron beams according to claim 1, further comprising:

5. The method for adjusting a multi-electron beam according to any one of claims 1 to 3, characterized in that a detector in which an aperture substrate having a plurality of openings formed therein is arranged on a detection element is used as the detector.

6. the first and second lenses adjusted by the method for adjusting a multi-electron beam according to any one of claims 1 to 3; The separator; the first deflector; the third lens; a detector for detecting multiple secondary electron beams that have passed through the separator, the first deflector, and the third lens; A multi-electron beam inspection device comprising:

7. The detector is a first detector, 7. A multi-electron beam inspection apparatus according to claim 6, further comprising a second detector for adjusting said first and second lenses.

8. 6. The method for adjusting multiple electron beams according to claim 5, wherein the detector has an aperture substrate on which the plurality of openings are formed, the aperture substrate being disposed on one detection element.

9. a separator for separating multiple secondary electron beams emitted due to irradiation of a substrate or a mark with the multiple primary electron beams from the multiple primary electron beams; first and second lenses disposed between the separator and the substrate to direct the multiple primary electron beams to the substrate; a first deflector that deflects the multiple secondary electron beams separated from the multiple primary electron beams by the separator toward a detector having an aperture substrate on a detection element, the aperture substrate having an aperture formed therein; a third lens disposed between the first deflector and the detector, the third lens directing the multiple secondary electron beams to the detector; A method for adjusting multiple electron beams of a multiple electron beam image acquisition apparatus, comprising: selecting one representative primary electron beam from the multiple primary electron beams; a step of acquiring a secondary electron image in which both a pattern image obtained by scanning the substrate or mark with the representative primary electron beam and an aperture image obtained by scanning the aperture substrate with the representative secondary electron beam are captured together, by scanning the substrate or mark with the representative primary electron beam for each combination of variable input values ​​to the first, second, and third lenses, scanning the substrate or mark with a representative secondary electron beam emitted from the substrate or mark by scanning with the representative primary electron beam, and detecting the scanned representative secondary electron beam with the detector; using a secondary electron image for each combination of input values ​​to the first, second, and third lenses to focus the representative secondary electron beam at a predetermined position of the first deflector and to obtain a combination of first and second focus input values ​​of the first and second lenses for focusing the representative primary electron beam on the substrate or the mark, and a third focus input value of the third lens for focusing the representative secondary electron beam on the detector; setting a first focus input value of the obtained combination to the first lens and setting a second focus input value of the obtained combination to the second lens; A method for adjusting multiple electron beams, comprising:

10. a separator for separating multiple secondary electron beams emitted due to irradiation of a substrate or a mark with the multiple primary electron beams from the multiple primary electron beams; first and second lenses disposed between the separator and the substrate to direct the multiple primary electron beams to the substrate; a first deflector that deflects the multiple secondary electron beams separated from the multiple primary electron beams by the separator toward a detector having an aperture substrate with openings formed therein and disposed on a detection element; a third lens disposed between the first deflector and the detector, the third lens directing the multiple secondary electron beams to the detector; A method for adjusting multiple electron beams of a multiple electron beam image acquisition apparatus, comprising: a step of acquiring a secondary electron image in which both a pattern image obtained by scanning the substrate or mark with the multi-primary electron beams and an aperture image obtained by scanning the aperture substrate with the multi-secondary electron beams are captured together, by scanning the substrate or mark with the multi-primary electron beams for each combination of variable input values ​​to the first, second, and third lenses, scanning the substrate or mark with the multi-secondary electron beams emitted from the substrate or mark by scanning with the multi-primary electron beams, and detecting the scanned multi-secondary electron beams with the detector so that two or more secondary electron beams are not incident on one aperture; acquiring a combination of first and second focus input values ​​of the first and second lenses for focusing the multiple secondary electron beams at a predetermined position of the first deflector and for focusing the multiple primary electron beams on the substrate or the mark, and a third focus input value of the third lens for focusing the multiple secondary electron beams on the detector, using a secondary electron image for each combination of input values ​​to the first, second, and third lenses; setting a first focus input value of the obtained combination to the first lens and setting a second focus input value of the obtained combination to the second lens; A method for adjusting multiple electron beams, comprising:

11. As the detector, a multi-detector is used in which an aperture substrate having a plurality of openings formed therein is arranged on a plurality of detection elements such that a different opening is located on each detection element, 11. The method for adjusting multiple electron beams according to claim 10, further comprising the step of setting a third focus input value of the acquired combination to the third lens.

12. 11. The method for adjusting multiple electron beams according to claim 10, wherein the aperture size of the multiple openings is smaller than the beam pitch of the multiple secondary electron beams on the aperture substrate.

13. the first and second lenses adjusted by the method for adjusting a multi-electron beam according to claim 10; The separator; the first deflector; the third lens; a multi-detector for detecting multiple secondary electron beams that have passed through the separator, the first deflector, and the third lens; A multi-electron beam inspection device comprising:

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