JP2021106108A - Electron beam inspection device - Google Patents

Abstract

To provide an electron beam inspection device capable of mounting a substrate to be inspected such that the upper face of the substrate has a predetermined reference height.SOLUTION: An electron beam inspection device includes: a movable stage on which a substrate to be inspected is mounted, the substrate having a pattern formed thereon; an image acquisition part irradiating the substrate with an electron beam to acquire a secondary electronic image of the substrate; and a comparison part comparing the secondary electronic image with a corresponding reference image. The stage includes: an XY stage movable in a planar direction; a pedestal provided above the XY stage; a lifting part provided on the pedestal to lift and lower the substrate; a canopy part provided with an opening in the central part thereof; and a cover provided on the outer periphery of the canopy part and including a peripheral wall part extending below the canopy part. The lower edge part of the peripheral wall part of the cover is directly or indirectly fixed to the pedestal. The substrate is inspected in a state where the substrate lifted by the lifting part is brought into contact with the lower face of the canopy part and the canopy part covers the periphery of the upper face of the substrate.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electron beam inspection device.

With the increasing integration of LSIs, the circuit line width required for semiconductor devices has been miniaturized year by year. In order to form a desired circuit pattern on a semiconductor device, a method of reducing and transferring a high-precision original image pattern formed on quartz on a wafer by using a reduction projection exposure apparatus is adopted.

Improving the yield is indispensable for manufacturing LSIs, which require a large manufacturing cost. With the miniaturization of the LSI pattern size formed on the semiconductor wafer, the size that must be detected as a pattern defect is also extremely small. Therefore, it is necessary to improve the accuracy of the pattern inspection apparatus for inspecting the defects of the ultrafine pattern transferred on the semiconductor wafer.

Further, one of the factors for lowering the yield is a pattern defect of a mask used when an ultrafine pattern is exposed and transferred on a semiconductor wafer by a photolithography technique. Therefore, it is necessary to improve the accuracy of the pattern inspection apparatus for inspecting defects in the transfer mask used in LSI manufacturing.

As a pattern defect inspection method, a method of comparing a measurement image obtained by imaging a pattern formed on a substrate such as a semiconductor wafer or a lithography mask with a measurement image obtained by imaging a design data or the same pattern on the substrate is known. Has been done. For example, "die to die inspection" that compares measurement image data obtained by imaging the same pattern at different locations on the same substrate, or design image data (reference image) based on pattern-designed design data. There is a "die to database (die database) inspection" in which the data is generated and the measured image, which is the measurement data obtained by capturing the pattern, is compared with the measured image. If the compared images do not match, it is determined that there is a pattern defect.

Development of an inspection device that scans (scans) the substrate to be inspected with an electron beam, detects secondary electrons emitted from the substrate due to the irradiation of the electron beam, and acquires a pattern image is in progress. In an inspection device using an electron beam, a column containing an electron gun or the like that emits an electron beam and an inspection room accommodating a stage on which an inspection target substrate is placed are connected. As the stage moves, the electron beam scans the substrate for inspection. In the inspection device, it is necessary to improve the measurement accuracy and suppress the damage to the substrate due to the irradiation of the electron beam. Therefore, the electron beam is accelerated with high energy, and a retarding voltage is applied to the substrate to decelerate the electron beam immediately before the electron beam is incident on the substrate.

In order to perform high-precision and high-resolution inspection, it is necessary to place the substrate on the stage so that the distance between the upper surface of the substrate to be inspected and the column is constant. However, since the thickness varies depending on the substrate, it is difficult to keep the distance between the upper surface of the substrate placed on the stage and the column constant.

In an electron beam drawing device, which is an example of a device that irradiates a substrate with an electron beam, a mask substrate (mask blanks) on which a glass substrate, a chrome film, and a resist film are laminated is irradiated with an electron beam to draw a desired pattern. .. In the electron beam drawing apparatus, a mask cover H as shown in FIGS. 9 (a) and 9 (b) is used to ground the mask substrate. 9 (b) is a cross-sectional view taken along the line IXb-IXb of FIG. 9 (a).

The mask cover H has conductivity, and is provided with a plurality of grounding mechanisms 32 on a frame-shaped frame 31 having an opening 30 at the center. The size of the frame 31 is slightly larger than that of the mask substrate, and the size of the opening 30 is slightly smaller than that of the mask substrate.

Each grounding mechanism 32 has a grounding plate 33 which is a plate-shaped conductor connected to the frame body 31. The ground plate 33 is provided so that one end projects to the outside of the frame body 31 and the other end projects to the inside of the opening of the frame body 31. At one end of the ground plate 33, a support pin 34 that supports the ground plate 33 and grounds during drawing is provided. At the other end of the ground plate 33, a ground pin 35 is provided so as to project downward. FIG. 9A shows an example in which three grounding mechanisms 32 are provided. The plurality of grounding mechanisms 32 are arranged at equal intervals on the frame body 31.

As shown in FIG. 9C, when the mask cover H is set on the mask substrate 90 in which the light-shielding film (for example, a chrome film) 92 and the resist film 93 are laminated on the glass substrate 91, the earth pin 35 is set by the weight of the mask cover H. Breaks through the resist film 93 and comes into contact with the light-shielding film 92, which is a conductor.

With the mask cover H placed on the mask substrate 90 in this way, drawing by an electron beam is performed on the mask substrate 90. At this time, the mask cover H is connected to a ground (not shown). The electric charge accumulated on the mask substrate 90 by the irradiation of the electron beam is discharged through the mask cover H.

Since the mask cover H used in the electron beam drawing apparatus is simply placed on the mask substrate 90, the height of the upper surface of the mask substrate 90 changes depending on the thickness of the mask substrate 90. Therefore, even if the mask cover H is applied to the inspection device, it is difficult to keep the distance between the upper surface of the substrate to be inspected placed on the stage and the column constant.

Japanese Unexamined Patent Publication No. 2008-27737 Japanese Unexamined Patent Publication No. 2016-127023 Japanese Unexamined Patent Publication No. 2009-245953 JP-A-2010-257994

An object of the present invention is to provide an electron beam inspection apparatus capable of mounting a substrate on a stage so that the upper surface of the substrate has a predetermined reference height.

The electron beam inspection apparatus according to one aspect of the present invention has a movable stage on which a substrate to be inspected having a pattern is placed, and the substrate is irradiated with an electron beam to acquire a secondary electron image of the substrate. An image acquisition unit and a comparison unit for comparing the secondary electronic image with a corresponding reference image are provided. The stage includes an XY stage that can be moved in the plane direction, a pedestal provided on the XY stage, an elevating portion provided on the pedestal for raising and lowering the substrate, and a canopy provided with an opening in the center. It has a portion and a cover provided on the outer periphery of the canopy portion and including a peripheral wall portion extending below the canopy portion. The lower end of the peripheral wall portion of the cover is directly or indirectly fixed to the pedestal, the substrate raised by the elevating portion comes into contact with the lower surface of the canopy portion, and the canopy portion is on the upper surface of the substrate. The substrate is inspected while covering the peripheral edge portion.

In one aspect of the present invention, the canopy portion has a support portion and an inward extending portion extending from the supporting portion toward the opening, and projects downward from the lower surface of the inward extending portion. An electrode pin for applying a predetermined retarding voltage is provided on the substrate.

In one aspect of the present invention, the support portion projects below the inwardly extending portion.

In one aspect of the present invention, a plurality of the electrode pins are provided.

In one aspect of the present invention, the elevating part has an elevating plate on which the substrate is placed, and an electrode for applying a predetermined retarding voltage to the substrate is provided on the upper surface of the plate. ..

According to the present invention, the substrate can be placed on the stage so that the upper surface of the substrate has a predetermined reference height.

It is a schematic block diagram of the pattern inspection apparatus by embodiment of this invention. It is a top view of the molded aperture array substrate. It is a schematic block diagram of a stage. It is a schematic block diagram of a lift table. It is a perspective view of a cover. It is a perspective view of the cover turned upside down. FIG. 5 is a cross-sectional view taken along the line VII-VII of FIG. (A) to (e) are diagrams for explaining the movement of the substrate. (A) is a plan view of a mask cover according to a comparative example, (b) is a cross-sectional view of the mask cover, and (c) is a view showing a state in which the mask cover is set on a mask substrate.

Hereinafter, in the embodiment, as an example of a method of imaging the pattern formed on the substrate to be inspected (acquiring the image to be inspected), the substrate to be inspected is irradiated with a multi-beam by an electron beam to obtain a secondary electron image. The configuration for imaging will be described. However, the present invention is not limited to the multi-beam, and the substrate to be inspected may be irradiated with a single beam to image a secondary electron image.

FIG. 1 shows a schematic configuration of a pattern inspection device according to an embodiment of the present invention. In FIG. 1, the inspection device 100 for inspecting a pattern formed on a substrate is an example of an electron beam inspection device. The inspection device 100 is an example of a multi-beam inspection device. The inspection device 100 is an example of an electron beam image acquisition device. Further, the inspection device 100 is an example of a multi-beam image acquisition device.

The inspection device 100 includes an image acquisition mechanism 150 and a control system circuit 160 (control unit). The image acquisition mechanism 150 includes a main electron beam column 102, a sub-electron beam column 104, an examination room 103, a detection circuit 106, a chip pattern memory 123, a drive mechanism 142, and a laser length measuring system 122.

In the main electron beam column 102, an electron gun 201, an illumination lens 202, a molded aperture array substrate 203, a reduction lens 205, a limiting aperture substrate 206, an objective lens 207, a main deflector 208, a sub-deflector 209, and a batch blanking deflection are included. A vessel 212 and a beam separator 214 are arranged. The primary electron optics system is composed of a reduction lens 205, a limiting aperture substrate 206, an objective lens 207, a main deflector 208, a sub-deflector 209, and a batch blanking deflector 212. However, the configuration of the primary electron optics system is not limited to this. Other optical elements and the like may be arranged.

A projection lens 224, 226, a deflector 228, and a multi-detector 222 are arranged in the sub-electron beam column 104. The beam separator 214, the projection lenses 224, 226, and the deflector 228 constitute a secondary electron optics system. However, the configuration of the secondary electron optics system is not limited to this. Other optical elements and the like may be arranged. The multi-detector 222 is connected to the detection circuit 106 outside the sub-electron beam column 104. The detection circuit 106 is connected to the chip pattern memory 123.

In the examination room 103, a stage 400 that can be moved in the XY plane direction and the height direction is arranged. A substrate 101 to be inspected is arranged on the stage 400. 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. By exposing and transferring the chip pattern formed on the exposure mask substrate to the semiconductor substrate a plurality of times, a plurality of chip patterns (wafer dies) are formed on the semiconductor substrate.

The substrate 101 is arranged on the stage 400, for example, with the pattern forming surface facing upward. Further, on the stage 400, a mirror 216 that reflects the laser beam for laser length measurement emitted from the laser length measuring system 122 arranged outside the examination room 103 is arranged.

In the control system circuit 160, the control computer 110 that controls the entire inspection device 100 uses a bus to control the position circuit 107, the comparison circuit 108, the reference image creation circuit 112, the stage control circuit 114, the lens control circuit 124, and the blanking control. It is connected to a circuit 126, a deflection control circuit 128, a storage device 109 such as a magnetic disk device, a monitor 117, a memory 118, and a printer 119.

The deflection control circuit 128 is connected to DAC (digital-to-analog conversion) amplifiers 144 and 146. The DAC amplifier 146 is connected to the main deflector 208, and the DAC amplifier 144 is connected to the sub-deflector 209. The chip pattern memory 123 is connected to the comparison circuit 108.

The stage 400 is driven by a drive mechanism 142 under the control of the stage control circuit 114. The stage 400 can move in the horizontal direction, the height direction, and the rotational direction. The moving position of the stage 400 is measured by the laser length measuring system 122 and supplied to the position circuit 107. The laser length measuring system 122 measures the position of the stage 400 by the principle of the laser interferometry method by receiving the reflected light from the mirror 216.

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 the filament and the extraction electrode (not shown) in the electron gun 201, and the voltage of a predetermined extraction electrode (Wenert) is applied. By the application and heating of the cathode at a predetermined temperature, the electron group emitted from the cathode is accelerated and emitted as an electron beam 200.

For the illumination lens 202, the reduction lens 205, the objective lens 207, and the projection lenses 224 and 226, for example, an electromagnetic lens is used, and both are controlled by the lens control circuit 124. The beam separator 214 is also controlled by the lens control circuit 124.

The collective blanking deflector 212 and the deflector 228 are each composed of a group of electrodes having at least two poles, and are controlled by the blanking control circuit 126. The main deflector 208 and the sub deflector 209 are composed of a group of electrodes having at least four poles. The main deflector 208 is controlled by the deflection control circuit 128 via a DAC amplifier 146 arranged for each electrode. Similarly, the sub-deflector 209 is controlled by the deflection control circuit 128 via the DAC amplifier 144 arranged for each electrode.

As shown in FIG. 2, the molded aperture array substrate 203 is formed with openings 22 of vertical (y direction) m rows × horizontal (x directions) n columns (m, n ≧ 2) at a predetermined arrangement pitch. .. Each opening 22 is formed by a rectangle having the same dimensions and shape. Each opening 22 may be circular with the same outer diameter.

The image acquisition mechanism 150 acquires an image to be inspected of the graphic pattern from the substrate 101 on which the graphic pattern is formed by using the multi-beam 20 using the electron beam.

The electron beam 200 emitted from the electron gun 201 (emission source) illuminates the entire molded aperture array substrate 203 substantially vertically by the illumination lens 202. As shown in FIG. 2, a plurality of rectangular openings 22 are formed in the molded aperture array substrate 203, and the electron beam 200 illuminates the area including all the openings 22. By passing a part of the electron beam 200 through the plurality of openings 22 of the molded aperture array substrate 203, for example, a plurality of rectangular primary electron beams (multi-beams) 20 are formed.

The multi-beam 20 then formed a crossover (CO), passed through a beam separator 214 located at the crossover position, was reduced by the reduction lens 205, and was formed on the limiting aperture substrate 206. Proceed towards the central hole.

When the entire multi-beam 20 is collectively deflected by the batch blanking deflector 212 arranged between the molded aperture array substrate 203 and the reduction lens 205, the position is located from the central hole of the limiting aperture substrate 206. The multi-beam 20 is shielded by the detached and limiting aperture substrate 206.

On the other hand, the multi-beam 20 not deflected by the batch blanking deflector 212 passes through the central hole of the limiting aperture substrate 206 as shown in FIG. By turning ON / OFF of the batch blanking deflector 212, blanking control is performed, and ON / OFF of the beam is collectively controlled.

In this way, the limiting aperture substrate 206 shields the multi-beam 20 deflected so that the beam is turned off by the batch blanking deflector 212. Then, the multi-beam 20 for inspection is formed by the beam group that has passed through the limiting aperture substrate 206 formed from the time when the beam is turned on to the time when the beam is turned off.

The multi-beam 20 that has passed through the limiting aperture substrate 206 is focused on the substrate 101 surface by the objective lens 207 to obtain a pattern image (beam diameter) having a desired reduction ratio, and is restricted by the main deflector 208 and the sub-deflector 209. The entire multi-beam 20 that has passed through the aperture substrate 206 is collectively deflected in the same direction, and each beam is irradiated to each irradiation position on the substrate 101.

For example, scanning is performed while continuously moving the stage 400. Therefore, the main deflector 208 performs tracking deflection so as to follow the movement of the stage 400. Then, the sub-deflector 209 collectively deflects the entire multi-beam 20 so that each beam scans in the corresponding region.

The multi-beams 20 irradiated at one time are ideally arranged at a pitch obtained by multiplying the arrangement pitch of the plurality of openings 22 of the molded aperture array substrate 203 by the desired reduction ratio described above.

In this way, the main electron beam column 102 irradiates the substrate 101 with the two-dimensional multi-beam 20 at a time. A bundle of secondary electrons containing backscattered electrons (multi-secondary electron beam 300) corresponding to each beam from the substrate 101 to the multi-beam 20 due to the irradiation of the multi-beam 20 at a desired position on the substrate 101 (multi-secondary electron beam 300). (Dashed line in FIG. 1) is emitted.

The multi-secondary electron beam 300 emitted from the substrate 101 is refracted by the objective lens 207 toward the center side of the multi-secondary electron beam 300, and proceeds toward the central hole formed in the limiting aperture substrate 206. The multi-secondary electron beam 300 that has passed through the limiting aperture substrate 206 is refracted by the reduction lens 205 substantially parallel to the optical axis, and proceeds to the beam separator 214.

The beam separator 214 generates an electric field and a magnetic field in a direction orthogonal to each other on a plane orthogonal to the direction (optical axis) in which the multi-beam 20 travels. The electric field exerts a force in the same direction regardless of the traveling direction of the electron. 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 electron can be changed depending on the invasion direction of the electron.

The force due to the electric field and the force due to the magnetic field cancel each other out to the multi-beam 20 (primary electron beam) that enters the beam separator 214 from above, and the multi-beam 20 travels straight downward. On the other hand, in the multi-secondary electron beam 300 that invades the beam separator 214 from below, both the force due to the electric field and the force due to the magnetic field act in the same direction, and the multi-secondary electron beam 300 is obliquely upward. Can be bent.

The multi-secondary electron beam 300 bent obliquely upward is collectively guided to the multi-detector 222 side while being refracted by the projection lenses 224 and 226. The induced multi-secondary electron beam 300 is projected onto the multi-detector 222. The multi-detector 222 detects the projected multi-secondary electron beam 300.

The secondary electron detection data (measured image: secondary electron image: inspected image) detected by the multi-detector 222 is output to the detection circuit 106 in the order of measurement. In the detection circuit 106, analog detection data is converted into digital data by an A / D converter (not shown) and stored in the chip pattern memory 123. In this way, the image acquisition mechanism 150 acquires a measurement image of the pattern formed on the substrate 101.

The reference image creation circuit 112 is a reference image for each mask die based on the design data that is the basis for forming the pattern on the substrate 101 or the design pattern data defined in the exposure image data of the pattern formed on the substrate 101. To create. For example, the design pattern data is read from the storage device 109 through the control computer 110, and each graphic pattern defined in the read design pattern data is converted into binary or multi-valued image data.

The figure defined in the design pattern data is, for example, a basic figure of a rectangle or a triangle. For example, the coordinates (x, y) at the reference position of the figure, the length of the side, and the figure type such as the rectangle or the triangle are distinguished. Graphical data that defines the shape, size, position, etc. of each pattern graphic is stored with information such as a graphic code that serves as an identifier.

When the design pattern data to be the graphic data is input to the reference image creation circuit 112, the data is expanded to the data for each graphic, and the graphic code indicating the graphic shape of the graphic data, the graphic dimensions, and the like are interpreted. Then, the image data of a binary or multi-valued design pattern is developed and output as a pattern arranged in a grid having a grid of predetermined quantization dimensions as a unit.

In other words, the design data is read, the inspection area is virtually divided into squares with a predetermined dimension as a unit, the occupancy rate of the figure in the design pattern is calculated for each square, and the n-bit occupancy rate data is obtained. Output. For example, it is preferable to set one square as one pixel. Then, when to have a resolution of 1/2 8 ^{(= 1/256)} to 1 pixel, the occupancy rate of the pixel allocated the small area region amount corresponding 1/256 of figures are arranged in a pixel Calculate. Then, it is output to the reference circuit 112 as 8-bit occupancy rate data. The squares (inspection pixels) may be matched with the pixels of the measurement data.

Next, the reference image creation circuit 112 applies an appropriate filter process to the design image data of the design pattern, which is the image data of the figure. The optical image data as a measurement image is in a state in which a filter is acted by an optical system, in other words, a continuously changing analog state. Therefore, the image data of the design pattern whose image intensity (shade value) is the image data on the design side of the digital value can also be filtered to match the measurement data. The image data of the created reference image is output to the comparison circuit 108.

The comparison circuit 108 compares the measured image measured from the substrate 101 with the corresponding reference image. Specifically, the aligned image to be inspected and the reference image are compared for each pixel. Using a predetermined determination threshold value, the two are compared for each pixel according to a predetermined determination condition, and the presence or absence of a defect such as a shape defect is determined. For example, if the gradation value difference for each pixel is larger than the determination threshold value Th, it is determined as a defect candidate. Then, the comparison result is output. The comparison result may be stored in the storage device 109 or the memory 118, displayed on the monitor 117, or printed out from the printer 119.

In addition to the die-database inspection described above, a die-die inspection may be performed. When performing a die-die inspection, measurement image data obtained by capturing the same pattern at different locations on the same substrate 101 are compared with each other. Therefore, the image acquisition mechanism 150 uses the multi-beam 20 (electron beam) to form one graphic pattern (first graphic pattern) from the substrate 101 in which the same graphic patterns (first and second graphic patterns) are formed at different positions. The measurement image which is the secondary electronic image of each of the graphic pattern (the graphic pattern of the above) and the other graphic pattern (the second graphic pattern) is acquired. In this case, the measured image of one of the acquired graphic patterns becomes the reference image, and the measured image of the other graphic pattern becomes the image to be inspected. The images of one graphic pattern (first graphic pattern) and the other graphic pattern (second graphic pattern) to be acquired may be in the same chip pattern data, or may be divided into different chip pattern data. May be good. The inspection method may be the same as the die database inspection.

Next, the configuration of the stage 400 will be described. As shown in FIG. 3, the stage 400 includes an XY stage 404 installed on the bottom surface of the examination room 103 via a spacer 402, a Z stage 408 installed on the XY stage via an adapter plate 406, and Z. It includes a pedestal 410 provided on the stage 408, a lift table 420 fixed on the pedestal 410, and a cover 430 provided on the lift table 420.

As shown in FIG. 4, the lift table 420 (elevating portion) has a main body 421, a rod 422 extending in the vertical direction from the main body 421, and a plate 423 provided at the upper end of the rod 422. The substrate 101 is placed on the plate 423. The rod 422 supports the plate 423 in an ascending / descending manner. When the rod 422 moves up and down (or expands and contracts) by a vertical actuator (not shown), the substrate 101 moves up and down together with the plate 423. When irradiating the substrate 101 with a beam, the lift table 420 raises the substrate 101 to the electrode pins 435 (see FIG. 7) provided on the lower surface side of the canopy portion 431 (see FIGS. 5 to 7) of the cover 430. The upper surface of the substrate 101 is pressed against it.

5 is a perspective view of the cover 430, FIG. 6 is an upside-down perspective view of the cover 430, and FIG. 7 is a sectional view taken along line VII-VII of FIG.

The cover 430 is made of titanium, for example, and is provided on a stepped (L-shaped cross section) canopy portion 431 (ceiling portion) having a substantially rectangular opening 432 in the center portion and on the outer periphery of the canopy portion 431. It has a peripheral wall portion 433 that extends downward from the canopy portion 431. The lower surface of the peripheral wall portion 433 is fixed to the upper surface of the main body 421 of the lift table 420, and the main body 421 of the lift table 420 and the cover 430 are connected to each other. The upper surface of the canopy portion 431 and the upper surface of the peripheral wall portion 433 are flush with each other (substantially flush with each other).

A notch 434 is provided in a part of the lower edge portion of the peripheral wall portion 433. As will be described later, the notch 434 serves as a carry-in / out port for carrying the board 101 into the cover 430 and carrying out the board 101 from the cover 430.

A plurality of electrode pins 435 are provided in the vicinity of the opening 432 on the lower surface of the canopy portion 431 so as to project downward. For example, three electrode pins 435a, 435b, and 435c (not shown) are provided on the peripheral edge of the opening 432 so as to be stable and self-supporting. As shown in FIG. 8C, when the substrate 101 is raised by the lift table 420 and comes into contact with the electrode pins 435, the electrode pins 435 to the substrate 101 are predetermined via a conducting wire (not shown) provided inside the cover 430. The retarding voltage can be applied.

Further, when the substrate 101 to be inspected is a mask substrate 90 in which a glass substrate 91, a chromium film 92, and a resist film 93 are laminated as shown in FIG. 9C, the resist film which is an insulating film is pierced. It is necessary to make the chromium film, which is a conductive film, and the electrode pin 435 conductive, and apply a retarding voltage. In the present embodiment, the substrate 101 is pressed against the electrode pin 435 by the lift table 420 to break through the insulating film and apply the retarding voltage. For example, among the electrode pins 435a, 435b, and 435c, the electrode pin 435a As a structure that insulates from other electrode pins 435b, 435c and the inward extending portion 431a, by applying a voltage different from the other electrode voltage to the electrode pin 435a, the potential difference causes dielectric breakdown in the insulating film of the substrate 101. It is also possible to generate conduction.

The canopy portion 431 is composed of a support portion 431b and an inward extending portion 431a extending from the support portion 431b toward the inner opening 432. The upper surface of the inward extending portion 431a and the upper surface of the supporting portion 431b are flush with each other (substantially flush with each other). The inward extending portion 431a is thinner than the supporting portion 431b, and the supporting portion 431b projects downward from the inward extending portion 431a. The electrode pin 435 is provided so as to project downward from the lower surface of the inward extending portion 431a. The inward extending portion 431a and the supporting portion 431b may be adhesively bonded or integrally processed. Further, the canopy portion 431 may be adhesively bonded to the peripheral wall portion 433, or may be integrally processed.

When the width of the opening 432 is W1, the width of the inward extending portion 431a is W2, and the size (width) of the substrate 101 is D, W1 <D <W1 + 2 × W2. W1 is about 120 to 150 mm, and W2 is about 1 to 3 mm.

As shown in FIGS. 8A and 8B, the substrate 101 to be inspected is carried into the cover 430 through the notch 434 and placed on the plate 423. As shown in FIG. 8C, the plate 423 is raised, the substrate 101 is pressed against the lower surface side of the canopy portion 431, and comes into contact with the electrode pin 435. The lift table 420 monitors the load applied to the rod 422, detects the load change due to the substrate 101 coming into contact with the cover 430 (electrode pin 435), and stops the plate 423 from rising. A retarding voltage is applied to the substrate 101 via the electrode pins 435.

When the inspection of the substrate 101 is completed, as shown in FIGS. 8 (d) and 8 (e), the plate 423 is lowered, and the substrate 101 is carried out of the cover 430 through the notch 434.

As described above, since the diameter W1 of the opening 432 is smaller than the size D of the substrate 101, when the substrate 101 is inspected, the peripheral edge of the upper surface of the substrate 101 is formed by the inward extending portion 431a of the canopy portion 431 of the cover 430. Be covered. Further, since the substrate 101 is arranged inside the support portion 431b in a state where the substrate 101 is in contact with the electrode pin 435, it is possible to suppress the positional deviation in the plane direction.

As described above, when the mask cover H as shown in FIGS. 9 (a) and 9 (b) is used, it is difficult to keep the distance between the upper surface of the substrate placed on the stage and the column constant. there were. On the other hand, in the present embodiment, the substrate 101 is inspected by pressing the substrate 101 against the lower surface side of the canopy portion 431 of the cover 430. The cover 430 is fixed to the main body 421 of the lift table 420. The height of the upper surface of the substrate 101 at the time of inspection is constant regardless of the thickness of the substrate 101, the distance between the upper surface of the substrate 101 and the main electron beam column 102 can be kept constant, and the discharge risk can be reduced. Further, since the rigidity of the retarding voltage application electrode structure can be increased by a simple structure in which the substrate 101 is pressed against the lower surface side of the canopy portion 431, it is easy to thin the structure above the substrate 101, and the substrate 101 The distance between the upper surface of the main electron beam column 102 and the main electron beam column 102 can be reduced. As a result, high-precision and high-resolution inspection becomes possible.

In the above embodiment, an example in which a retarding voltage is applied from the electrode pin 435 to the substrate 101 has been described, but a flat plate-shaped electrode that applies a retarding voltage to the upper surface of the plate 423 of the lift table 420 from the lower surface side of the substrate 101. May be provided. The substrate 101 to be inspected is, for example, an EUV mask. In this case, the electrode pin 435 provided on the cover 430 does not need to be connected to a conducting wire for applying a voltage, and may simply be a pin for contacting the upper surface of the substrate 101, or the pin may be omitted. You may.

In the above embodiment, the cover 430 (the lower end of the peripheral wall portion 433) is connected to the main body 421 of the lift table 420, that is, the cover 430 is indirectly fixed to the pedestal 410 via the main body 421. , The cover 430 (the lower end of the peripheral wall portion 433) may be directly fixed to the pedestal 410.

In the above embodiment, the example of using the electron beam has been described, but other charged particle beams such as an ion beam may be used.

The present invention is not limited to the above embodiment as it is, and at the implementation stage, the components can be modified and embodied within a range that does not deviate from the gist thereof. In addition, various inventions can be formed by an appropriate combination of the plurality of components disclosed in the above-described embodiment. For example, some components may be removed from all the components shown in the embodiments. In addition, components across different embodiments may be combined as appropriate.

20 Primary electron beam 100 Inspection device 101 Substrate 102 Main electron beam column 103 Inspection room 104 Secondary electron beam column 201 Electron gun 222 Multi detector 300 Multi secondary electron beam 400 Stage 402 Spacer 404 XY stage 406 Adapter plate 408 Z stage 410 Pedestal 420 lift table 430 cover

Claims (5)

A movable stage on which the patterned substrate to be inspected is placed, and
An image acquisition unit that irradiates the substrate with an electron beam and acquires a secondary electron image of the substrate.
A comparison unit that compares the secondary electron image with the corresponding reference image,
With
The stage
An XY stage that can be moved in the plane direction,
The pedestal provided on the XY stage and
An elevating part provided on the pedestal for raising and lowering the substrate,
A canopy portion having an opening in the central portion, and a cover provided on the outer periphery of the canopy portion and including a peripheral wall portion extending below the canopy portion.
Have,
The lower end of the peripheral wall portion of the cover is directly or indirectly fixed to the pedestal.
An electron beam inspection device for inspecting a substrate in a state where the substrate raised by the elevating portion comes into contact with the lower surface side of the canopy portion and the canopy portion covers the peripheral edge portion of the upper surface of the substrate. .. The canopy portion has a support portion and an inward extending portion extending from the supporting portion toward the opening, and projects downward from the lower surface of the inward extending portion to form a litter on the substrate. The electron beam inspection apparatus according to claim 1, wherein an electrode pin for applying a ding voltage is provided. The electron beam inspection apparatus according to claim 2, wherein the support portion projects below the inward extending portion. The electron beam inspection apparatus according to claim 2 or 3, wherein a plurality of the electrode pins are provided. The elevating portion has a plate that can be raised and lowered on which the substrate is placed, and an electrode for applying a predetermined retarding voltage to the substrate is provided on the upper surface of the plate. The electron beam inspection apparatus according to 1.

Images