JP2021096939A - Multi-electron beam image acquisition device - Google Patents

Abstract

To provide a multi-electron beam image acquisition device capable of performing inspection with excellent accuracy and efficiency regardless of beam deterioration.SOLUTION: A multi-electron beam image acquisition device includes an aberration detection unit for detecting the aberration of a multi-secondary electron beam, a deterioration determination unit for determining deterioration or non-deterioration of the multi-secondary electron beam based on the detected aberration, and a beam arrangement control unit for controlling a beam arrangement of a multi-primary electron beam so that the beam arrangement does not include a primary electron beam corresponding to a secondary electron beam determined to have been deteriorated and becomes a special beam arrangement with which an inspection area of a substrate can be scanned neither excessively nor deficiently.SELECTED DRAWING: Figure 1

Description

The present invention relates to a multi-electron beam image acquisition device.

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 narrower and narrower. Further, improvement of the yield is indispensable for manufacturing an LSI, which requires a large manufacturing cost. However, as represented by 1 gigabit class DRAM (random access memory), the patterns constituting the LSI are on the order of submicron to nanometer. In recent years, with the miniaturization of LSI pattern dimensions formed on semiconductor wafers, the dimensions that must be detected as pattern defects have become 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. In addition, one of the major factors for reducing the yield is a pattern defect of a mask used when exposing and transferring an ultrafine pattern on a semiconductor wafer by photolithography technology. 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 an inspection method, a method of inspecting by comparing a measurement image obtained by imaging a pattern formed on a substrate such as a semiconductor wafer or a lithography mask with design data or a measurement image obtained by imaging the same pattern on the substrate. It has been known. For example, as a pattern inspection method, "die to die inspection" in which measurement image data obtained by imaging the same pattern in different places on the same substrate are compared with each other, or a design image based on pattern-designed design data. There is a "die to database (die database) inspection" that generates data (reference image) and compares it with the measurement image that is the measurement data obtained by imaging the pattern. The captured image is sent to the comparison circuit as measurement data. In the comparison circuit, after the images are aligned with each other, the measurement data and the reference data are compared according to an appropriate algorithm, and if they do not match, it is determined that there is a pattern defect.

The pattern inspection device described above includes a device that irradiates a substrate to be inspected with a laser beam to capture a transmitted image or a reflected image thereof, and scans the substrate to be inspected with an electron beam to obtain an electron beam. Development of an inspection device that acquires a pattern image by detecting secondary electrons emitted from the substrate to be inspected due to irradiation is also in progress. As for the inspection device using the electron beam, the development of the device using the multi-beam is also in progress.

Japanese Unexamined Patent Publication No. 2004-200509

However, in an inspection device using a multi-beam, when the multi-beams are arranged in a rectangular shape as a whole, the beams arranged at the four corners of the multi-beams are separated from the center of the multi-beams and therefore have more aberrations than the other beams. It can grow. Further, as the optical characteristics of the inspection device change over time, the aberrations of the beams arranged at the four corners may become larger. If the aberrations of the beams arranged at the four corners become too large, the accuracy of the inspection will deteriorate. On the other hand, simply disabling the beams arranged at the four corners in order to suppress the aberration of the multi-beam does not allow the multi-beam to scan the inspection area in just proportion. The inability to scan the inspection area in just proportion deteriorates the accuracy and efficiency of inspection.

An object of the present invention is to provide a multi-electron beam image acquisition device capable of performing inspection with good accuracy and efficiency regardless of beam deterioration.

The multi-electron beam image acquisition device according to one aspect of the present invention is a multi-electron beam image acquisition device that irradiates a substrate with a multi-primary electron beam and acquires an image of a multi-secondary electron beam emitted from the substrate. , An aberration detection unit that detects the aberration of the multi-secondary electron beam, a deterioration judgment unit that determines the presence or absence of deterioration of the multi-secondary electron beam based on the detected aberration, and a secondary that is determined to be deteriorated. It is provided with a beam arrangement control unit that controls the beam arrangement of the multi-primary electron beam so as to have a specific beam arrangement that does not include the primary electron beam corresponding to the electron beam and can scan the inspection area of the substrate without excess or deficiency. ..

In the above-mentioned multi-electron beam image acquisition device, the specific beam arrangement is a square grid-like beam arrangement along the first movement direction of the stage on which the substrate is placed and the second movement direction orthogonal to the first movement direction. Therefore, even if the beam arrangement is such that the primary electron beams at the four corners including the primary electron beam corresponding to the secondary electron beam judged to be deteriorated when viewed as a whole multi-primary electron beam are missing. Good.

In the above-mentioned multi-electron beam image acquisition device, the square grid-like beam arrangement has the number of beams in the Kth row and the NA + Kth row when the first movement direction is the column direction and the second movement direction is the row direction. The beam arrangement may be such that the sum of the number of beams and the number of beams is M. However, M is the number of columns of the primary electron beam constituting the multi-primary electron beam, N is the number of rows of the primary electron beam constituting the multi-primary electron beam, and A is the number of beams in the column direction. 1/2 of the number of rows less than, K is any integer greater than or equal to 1 and less than or equal to A.

In the above-mentioned multi-electron beam image acquisition device, the beam arrangement control unit has a specific beam arrangement when the first inspection mode for inspecting the substrate in consideration of the deterioration state of the multi-secondary electron beam is set. When the second inspection mode is set to control the beam arrangement of the multi-primary electron beam and perform the inspection that prioritizes the inspection speed, the multi 1 is set so that the beam arrangement includes all the primary electron beams. When the third inspection mode is set to control the beam arrangement of the secondary electron beam and perform the inspection that prioritizes the inspection sensitivity, the multi-primary electrons are arranged so that the beam arrangement does not include the primary electron beam on the outer periphery. The beam arrangement of the beam may be controlled.

According to the present invention, the inspection can be performed with good accuracy and efficiency regardless of the deterioration of the beam.

It is a figure which shows an example of the pattern inspection apparatus by this embodiment. It is a perspective view which shows an example of the beam regulator in the pattern inspection apparatus by this Embodiment. It is a flowchart which shows the pattern inspection method by this Embodiment. It is a flowchart which shows the pattern inspection method by this embodiment different from FIG. It is a top view which shows the pattern inspection method by this Embodiment. FIG. 5 is a plan view showing a beam arrangement, a scanning area, and stripes in a high-speed inspection mode in the pattern inspection method according to the present embodiment. FIG. 5 is a plan view showing scanning of a scanning region by a multi-primary electron beam in a high-speed inspection mode in the pattern inspection method according to the present embodiment. FIG. 5 is a plan view showing a beam arrangement, a scanning region, and stripes in a high-sensitivity inspection mode in the pattern inspection method according to the present embodiment. FIG. 5 is a plan view showing a beam arrangement according to beam deterioration in the maintenance mode in the pattern inspection method according to the present embodiment. FIG. 5 is a plan view showing a beam arrangement according to beam deterioration different from that in FIG. 9 in the maintenance mode in the pattern inspection method according to the present embodiment. FIG. 5 is a plan view showing a beam arrangement according to beam deterioration different from that in FIGS. 9 and 10 in the maintenance mode in the pattern inspection method according to the present embodiment. It is a top view which shows the beam arrangement, the scanning area and the stripe in the maintenance mode in the pattern inspection method by this Embodiment. It is explanatory drawing for demonstrating the beam arrangement in the pattern inspection method by this Embodiment. FIG. 5 is a plan view showing a beam arrangement according to beam deterioration different from FIGS. 9 to 11 in the maintenance mode in the pattern inspection method according to the present embodiment. FIG. 5 is a plan view showing an example of beam arrangement in a high-speed inspection mode according to beam deterioration in the pattern inspection method of FIG. FIG. 5 is a plan view showing an example of beam arrangement in a high-sensitivity inspection mode according to beam deterioration in the pattern inspection method of FIG. FIG. 5 is a plan view showing a beam arrangement different from that of FIG. 16 in a high-sensitivity inspection mode according to beam deterioration in the pattern inspection method of FIG. It is a top view which shows the beam arrangement by one modification of this embodiment. It is a top view which shows the beam arrangement by one modification of this embodiment different from FIG. It is a figure which shows the pattern inspection apparatus by one modification of this embodiment.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. The embodiments are not limited to the present invention. Further, in the drawings referred to in the embodiment, the same parts or parts having the same functions are designated by the same reference numerals or similar reference numerals, and the repeated description thereof will be omitted.

(Pattern inspection device)
In the following embodiment, as an example of the multi-electron beam image acquisition device, a pattern inspection device for inspecting a pattern formed on a substrate using the multi-electron beam will be described.

FIG. 1 is a diagram showing an example of the pattern inspection device 1 in the present embodiment. The pattern inspection device 1 includes an image acquisition mechanism 2 and a control system circuit 3. The image acquisition mechanism 2 includes an electron beam column 21 (that is, an electron lens barrel) and an examination room 22.

Inside the electron beam column 21, an electron gun 23 (that is, a emission source), a condenser lens 24 composed of an electromagnetic lens, an aperture array substrate 25 which is an example of an aperture member, and a first intermediate composed of an electromagnetic lens. A lens 26, a beam adjuster 28 forming a part of a beam arrangement control unit, a first limiting diaphragm 29, and a second intermediate lens 210 composed of an electromagnetic lens are arranged. An electrostatic lens may be arranged inside each of the first intermediate lens 26 and the second intermediate lens 210. In the electron beam column 21, an objective lens 212 composed of an electromagnetic lens, an objective deflector 214, a beam separator 216, a bender 217, a first projection lens 218 composed of an electromagnetic lens, and electromagnetic waves are further contained. A second projection lens 220 composed of a lens, a second limiting aperture 221, a third projection lens 222 composed of an electromagnetic lens, a swingback deflector 223, and a multi-detector 224 are arranged. An electrostatic lens may be arranged inside each of the first projection lens 218, the second projection lens 220, and the third projection lens 222.

A stage 225 that can move at least in the XYZ direction is arranged in the examination room 22. A substrate 4 (that is, a sample) to be inspected is arranged on the stage 225. The substrate 4 includes a mask substrate for exposure and a semiconductor substrate such as a silicon wafer. When the substrate 4 is a semiconductor substrate, a plurality of chip patterns (that is, wafer dies) are formed on the semiconductor substrate. When the substrate 4 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 are formed on the semiconductor substrate. The substrate 4 is arranged on the stage 225, for example, with the pattern forming surface facing upward. Further, on the stage 225, a mirror 226 that reflects the laser beam for laser length measurement emitted from the laser length measuring system 5 arranged outside the examination room 22 is arranged. Further, a height position measurement sensor (that is, a Z sensor) 227 for measuring the height position of the four surfaces of the substrate is arranged on the inspection room 22. The Z sensor 227 irradiates the four surfaces of the substrate with laser light from diagonally above by a floodlight, receives the reflected light of the irradiated laser light with a receiver, and uses the received reflected light to position the height of the four surfaces of the substrate. To measure. The multi-detector 224 is connected to the detection circuit 6 outside the electron beam column 21. The detection circuit 6 is connected to the pattern memory 7 and the aberration detection circuit 315, which is an example of the aberration detection unit.

In the control system circuit 3, the control computer 31 that controls the entire pattern inspection device 1 uses the position detection circuit 33, the comparison circuit 34, the reference image creation circuit 35, the stage control circuit 36, the lens control circuit 38, and the deflection via the bus 32. It is connected to a control circuit 310, a beam arrangement setting circuit 317 that forms a part of a beam arrangement control unit, a storage device 311 such as a magnetic disk device, a monitor 312, a memory 313, and a printer 314.

DAC (digital-to-analog conversion) amplifiers 8A, 8B, and 8C are connected to the deflection control circuit 310. An objective deflector 214 is connected to the DAC amplifier 8A, a bender 217 is connected to the DAC amplifier 8B, and a swingback deflector 223 is connected to the DAC amplifier 8C. Each of the deflectors 214, 223 and the bender 217 is composed of electrodes having four or more poles, and is controlled by the deflection control circuit 310 for each electrode via the corresponding DAC amplifiers 8A, 8B, 8C.

A pattern memory 7 is connected to the comparison circuit 34. A drive mechanism 9 is connected to the stage control circuit 36, and a stage 225 is connected to the drive mechanism 9. The stage 225 is driven by the drive mechanism 9 under the control of the stage control circuit 36. The drive mechanism 9 is, for example, a three-axis motor that drives the stage 225 in the x, y directions (that is, the horizontal direction) and the θ direction (that is, the rotation direction) in the stage coordinate system orthogonal to the optical axis of the multi-primary electron beam. It has a drive system such as. As the 3-axis motor, for example, a step motor can be used. Further, the drive mechanism 9 can move the stage 225 in the Z direction (that is, the height direction) by using, for example, a piezo element or the like. The laser length measuring system 5 measures the position of the stage 225 by the principle of the laser interferometry by receiving the reflected light from the mirror 226, and supplies the measured moving position to the position detecting circuit 33.

The lens control circuit 38 controls the lenses 24, 26, 210, 212, 218, 220, 222 and the beam separator 216, respectively.

The beam arrangement setting circuit 317 sets the beam arrangement of the multi-primary electron beam 20, which will be described later. A beam adjustment control circuit 318 forming a part of the beam arrangement control unit is connected to the beam arrangement setting circuit 317. A beam adjuster 28 that forms a part of the beam arrangement control unit is connected to the beam adjustment control circuit 318. As shown in FIG. 2, the beam regulator 28 includes a substrate 281 provided with a hole 281a (that is, an opening) through which the multi-primary electron beam 20 passes for each individual primary electron beam 201, and a multi-primary electron. It has a pair of electrodes 282 and 283 arranged so as to sandwich the hole 281a on the surface of the substrate 281 on the incident side of the beam 20 and connected to the beam adjustment control circuit 318, respectively. Although FIG. 2 typically shows only one hole 281a, in reality, it is oriented in the x direction along the first moving direction of the stage 225 and in the second moving direction of the stage 225 orthogonal to the first moving direction. A plurality of holes 281a are provided in a square grid pattern at intervals in the y direction along the line. The beam adjustment control circuit 318 controls energization of the beam adjuster 28 according to the beam arrangement set by the beam arrangement setting circuit 317, and applies a voltage, that is, an electric field between the electrodes 282 and 283 of the beam adjuster 28. adjust. As a result, the beam regulator 28 applies an electromagnetic force corresponding to the applied voltage between the electrodes 282 and 283 to the primary electron beam 201 passing through the hole 281a, so that the multi 1 is applied to each primary electron beam 201. The focal point and directing direction of the next electron beam 20 are adjusted. By adjusting the focal point and the directivity direction of the multi-primary electron beam 20, the beam arrangement of the multi-primary electron beam 20 is controlled to be the beam arrangement set by the beam arrangement setting circuit 317. As shown in FIG. 1, a deterioration determination circuit 316, which is an example of a deterioration determination unit, is further connected to the beam arrangement setting circuit 317. An aberration detection circuit 315, which is an example of an aberration detection unit, is connected to the deterioration determination circuit 316, and a detection circuit 6 is connected to the aberration detection circuit 315.

A high-voltage power supply circuit (not shown) is connected to the electron gun 23. In the electron gun 23, an acceleration voltage is applied from a high-voltage power supply circuit between a filament (that is, a cathode) and an extraction electrode (that is, an anode) arranged inside, and a voltage is applied to another extraction electrode (that is, Wenert). Is applied, and the filament is further heated at a predetermined temperature to accelerate the electron group emitted from the filament and emit it as an electron beam 200.

The aperture array substrate 25 is provided with a plurality of holes (openings) 251 at intervals in the x-direction and the y-direction. The plurality of holes 251 are provided side by side in a square grid pattern at predetermined pitches along the x direction and the y direction.

Next, the operation of the image acquisition mechanism 2 in the pattern inspection device 1 will be described.

The electron beam 200 emitted from the electron gun 23 is refracted by the condenser lens 24 and illuminates the entire aperture array substrate 25. Then, a part of the electron beams 200 irradiated at the positions of the plurality of holes 251 of the aperture array substrate 25 pass through the plurality of holes 251 to form the multi-primary electron beam 20.

The formed multi-primary electron beam 20 is refracted by the first intermediate lens 26 and the second intermediate lens 210, and each primary electron beam constituting the multi-primary electron beam 20 is repeated while repeating the intermediate image and the crossover. It passes through the beam separator 216 arranged at the crossover position of 201 and proceeds to the objective lens 212. At this time, by adjusting the focal point and the directivity direction of the multi-primary electron beam 20 by the beam adjuster 28, the primary electron beam 201 deviated from the central hole of the first limiting diaphragm 29 is moved to the first limiting diaphragm 29. It can also be shielded by. The objective lens 212 focuses the multi-primary electron beam 20 on the substrate 4. The multi-primary electron beams 20 focused (that is, focused) on the four surfaces of the substrate by the objective lens 212 are collectively deflected by the objective deflector 214 and are collectively deflected on the substrate 4 of each primary electron beam 201. Each irradiation position is irradiated.

When the multi-primary electron beam 20 is irradiated to a desired position on the substrate 4, each primary of the multi-primary electron beam 20 is irradiated from the substrate 4 due to the irradiation of the multi-primary electron beam 20. A multi-secondary electron beam 300, which is a bundle of secondary electrons containing backscattered electrons corresponding to the electron beam 201, is emitted.

The multi-secondary electron beam 300 emitted from the substrate 4 passes through the objective lens 212 and proceeds to the beam separator 216.

Here, the beam separator 216 generates an electric field and a magnetic field in a direction orthogonal to the direction in which the central beam of the multi-primary electron beam 20 travels (that is, the central axis of the orbit). 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. With respect to the multi-primary electron beam 20 that penetrates the beam separator 216 from above, the force due to the electric field and the force due to the magnetic field cancel each other out, and the multi-primary electron beam 20 travels straight downward. On the other hand, with respect to the multi-secondary electron beam 300 that invades the beam separator 216 from below, 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 bent diagonally upward. It is separated from the multi-primary electron beam 20.

The multi-secondary electron beam 300 bent diagonally upward and separated from the multi-primary electron beam 20 is further bent by the bender 217 and projected onto the multi-detector 224 while being refracted by the projection lenses 218, 220 and 222. .. At this time, the secondary electron beam 301 deviated from the central hole of the second limiting diaphragm 221 due to refraction by the projection lenses 218 and 220 can be shielded by the second limiting diaphragm 221.

The multi-detector 224 has, for example, a diode-type two-dimensional sensor (not shown). The multi-detector 224 collides the multi-secondary electron beam 300 with the two-dimensional sensor to generate electrons from the two-dimensional sensor, so that the multi-secondary electron beam 300 projected on the multi-detector 224 is a two-dimensional electronic image. It is detected for each pixel as data. As a result, the image of the multi-secondary electron beam 300 is acquired. The multi-detector 224 outputs the detected two-dimensional electronic image data to the detection circuit 6.

The aberration detection circuit 315 acquires the detection result of the multi-secondary electron beam 300 by the detection circuit 6 from the detection circuit 6. The aberration detection circuit 315 detects the aberration of the multi-secondary electron beam 300 for each of the secondary electron beams 301 constituting the multi-secondary electron beam 300, based on the acquired detection result of the multi-secondary electron beam 300. .. The aberration detection circuit 315 outputs the aberration detection result of the multi-secondary electron beam 300 to the deterioration determination circuit 316.

The deterioration determination circuit 316 determines whether or not the multi-secondary electron beam 300 is deteriorated for each secondary electron beam 301 based on the aberration detection result of the multi-secondary electron beam 300 input from the aberration detection circuit 315. The deterioration determination circuit 316 outputs the determination result of the presence or absence of deterioration of the multi-secondary electron beam 300 to the beam arrangement setting circuit 317.

The beam arrangement setting circuit 317 sets the beam arrangement of the multi-primary electron beam 20 based on the determination result of the presence or absence of deterioration of the multi-secondary electron beam 300 input from the deterioration determination circuit 316. More specifically, the beam arrangement setting circuit 317 does not include the primary electron beam 201 corresponding to the secondary electron beam 301 determined to have deteriorated the beam arrangement of the multi-primary electron beam 20, and the substrate 4 has a beam arrangement setting circuit 317. The inspection area 41 (see FIG. 5) is set to a specific beam arrangement capable of scanning in just proportion. The beam arrangement setting circuit 317 outputs a setting result of a specific beam arrangement to the beam adjustment control circuit 318.

The beam adjustment control circuit 318 controls the energization of the beam regulator 28 corresponding to the specific beam arrangement based on the setting result of the specific beam arrangement input from the beam arrangement setting circuit 317, and controls the energization between the electrodes 282 and 283. Adjust the applied voltage. As a result, the focal point and directivity of the multi-primary electron beam 20 passing through the hole 281a are adjusted so as to have a specific beam arrangement, so that the beam arrangement of the multi-primary electron beam 20 is controlled to a specific beam arrangement. Will be done.

(Pattern inspection method)
Next, a pattern inspection method to which the pattern inspection apparatus 1 of FIG. 1 is applied will be described. Hereinafter, an example in which an exposure mask substrate is used as the substrate 4 will be described. FIG. 3 is a flowchart showing a pattern inspection method according to the present embodiment.

As shown in FIG. 3, first, the control computer 31 accepts an input operation of the inspection mode by the user prior to the inspection, and sets the inspection mode according to the input operation (step S1). In the present embodiment, as inspection modes, a maintenance mode (first inspection mode) in which an inspection considering the deterioration status of the multi-secondary electron beam 300 is performed and a high-speed inspection mode (first inspection mode) in which an inspection giving priority to the inspection speed is performed Two inspection modes) and a high-sensitivity inspection mode (third inspection mode) for performing an inspection that prioritizes inspection sensitivity can be selectively set. The beam arrangement setting circuit 317 acquires the inspection mode setting result from the control computer 31.

When the inspection mode setting result acquired from the control computer 31 is the high-speed inspection mode (step S2: high speed), the beam arrangement setting circuit 317 sets the beam arrangement for the high-speed inspection mode (step S3). More specifically, the beam arrangement setting circuit 317 sets the beam arrangement including all the primary electron beams 201 of the multi-primary electron beams 20.

After the beam arrangement for the high-speed inspection mode is set, the beam adjustment control circuit 318 performs energization control corresponding to the beam arrangement for the high-speed inspection mode set for the beam regulator 28.
The beam regulator 28 performs beam selection adjustment to select all the primary electron beams 201 according to this energization control (step S4). As a result, the beam arrangement of the multi-primary electron beam 20 is controlled to the beam arrangement for the high-speed inspection mode.

Under such a beam arrangement for the high-speed inspection mode, the pattern inspection apparatus 1 performs high-speed inspection (step S5).

The beam arrangement setting circuit 317 sets the beam arrangement for the high-sensitivity inspection mode when the inspection mode setting result acquired from the control computer 31 is the high-sensitivity inspection mode (step S2: high sensitivity) (step S6). .. More specifically, the beam arrangement setting circuit 317 sets the beam arrangement that does not include the primary electron beam 201 on the outer peripheral portion of the multi-primary electron beam 20.

After the beam arrangement for the high-sensitivity inspection mode is set, the beam adjustment control circuit 318 performs energization control corresponding to the beam arrangement for the high-sensitivity inspection mode set for the beam regulator 28, and the beam regulator 28 performs beam selection adjustment to select the primary electron beam 201 excluding the primary electron beam 201 on the outer peripheral portion according to this energization control (step S7). As a result, the beam arrangement of the multi-primary electron beam 20 is controlled to the beam arrangement for the high-sensitivity inspection mode.

Under such a beam arrangement for the high-sensitivity inspection mode, the pattern inspection apparatus 1 performs the high-sensitivity inspection (step S8).

When the inspection mode setting result acquired from the control computer 31 is the maintenance mode (step S2: maintenance), the beam arrangement setting circuit 317 transmits the aberration of the multi-secondary electron beam 300 to the aberration detection circuit 315 as the secondary electron beam. It is detected every 301 (step S9). The region on the substrate 4 on which the multi-secondary electron beam 300 for detecting the aberration is emitted, that is, the region on the substrate 4 on which the multi-primary electron beam 20 is irradiated to detect the aberration may be an arbitrary region. However, it may be a predetermined specific area. Further, the specific mode of detecting the aberration is not particularly limited, and for example, the intensity distribution of the detected secondary electron beam 301 with respect to the intensity distribution of the preset reference of the secondary electron beam 301 (when the aberration is zero). Aberrations may be detected by electrically detecting the difference between the two.

After the aberration of the multi-secondary electron beam 300 is detected, the deterioration determination circuit 316 determines whether or not the multi-secondary electron beam 300 is deteriorated for each secondary electron beam 301 based on the detected aberration (step S10). ). The deterioration determination circuit 316 determines whether or not the multi-secondary electron beam 300 is deteriorated based on whether or not the detected aberration is larger than the permissible value. That is, the deterioration determination circuit 316 determines that the corresponding secondary electron beam 301 is deteriorated when the detected aberration is larger than the allowable value, and on the other hand, when the detected aberration is equal to or less than the allowable value. , It is determined that the corresponding secondary electron beam 301 has not deteriorated.

When it is determined that at least one secondary electron beam 301 is deteriorated (step S10: Yes), the beam arrangement setting circuit 317 sets the beam arrangement for the maintenance mode according to the deterioration (step S11). More specifically, the beam arrangement setting circuit 317 does not include the primary electron beam corresponding to the secondary electron beam determined to be deteriorated, and can scan the inspection area 41 of the substrate 4 without excess or deficiency. To set. On the other hand, when it is determined that all the secondary electron beams 301 have not deteriorated (step S10: No), the process ends.

After the beam arrangement for the maintenance mode is set, the beam adjustment control circuit 318 performs energization control corresponding to the beam arrangement for the maintenance mode set for the beam adjuster 28, and the beam adjuster 28 performs this energization control. A beam that selects a primary electron beam 201 that does not include the primary electron beam 201 corresponding to the secondary electron beam 301 determined to be deteriorated according to the energization control and can scan the inspection area 41 of the substrate 4 without excess or deficiency. Selective adjustment is performed (step S12). As a result, the beam arrangement of the multi-primary electron beam 20 is controlled to the beam arrangement for the maintenance mode.

Under such a beam arrangement for the maintenance mode, the pattern inspection device 1 performs the maintenance mode inspection (step S13).

Next, with reference to the flowchart of FIG. 4, a pattern inspection method according to the present embodiment different from that of FIG. 3 will be described. FIG. 3 illustrates an example of setting the beam arrangement for the high-speed inspection mode in which all the primary electron beams 201 are used without considering the presence or absence of deterioration of the multi-secondary electron beam 300 when the high-speed inspection mode is set. did. On the other hand, in FIG. 4, the beam arrangement for the high-speed inspection mode is set according to the deterioration of the multi-secondary electron beam 300. Further, in FIG. 3, when the high-sensitivity inspection mode is set, the primary electron beam 201 that does not include the primary electron beam 201 on the outer peripheral portion is used without considering the presence or absence of deterioration of the multi-secondary electron beam 300. An example of setting the beam arrangement for the sensitivity inspection mode has been described. On the other hand, in FIG. 4, the beam arrangement for the high-sensitivity inspection mode is set according to the deterioration of the multi-secondary electron beam 300.

Specifically, as shown in FIG. 4, when the inspection mode setting result acquired from the control computer 31 is the high-speed inspection mode (step S2: high-speed), the beam arrangement setting circuit 317 is set in advance. It is determined whether or not the time (for example, period) for determining the deterioration of the secondary electron beam 300 has arrived (step S21).

When the time for determining deterioration has arrived (step S21: Yes), the beam arrangement setting circuit 317 causes the aberration detection circuit 315 to detect the aberration of the multi-secondary electron beam 300 for each secondary electron beam 301 (step S22). On the other hand, when the time for determining deterioration has not arrived (step S21: No), the beam arrangement setting circuit 317 has all the primary elements of the multi-primary electron beam 20 as the beam arrangement for the normal high-speed inspection mode. A beam arrangement including the electron beam 201 is set (step S3).

After the aberration of the multi-secondary electron beam 300 is detected, the deterioration determination circuit 316 determines whether or not the multi-secondary electron beam 300 is deteriorated for each secondary electron beam 301 based on the detected aberration (step S23). ).

When it is determined that at least one secondary electron beam 301 is deteriorated (step S23: Yes), the beam arrangement setting circuit 317 sets the beam arrangement for high-speed inspection according to the deterioration (step S24).

On the other hand, when it is determined that all the secondary electron beams 301 have not deteriorated (step S23: No), the beam arrangement setting circuit 317 sets the beam arrangement for the normal high-speed inspection mode (step S3).

After the beam arrangement for the high-speed inspection mode is set in step S24 or step S3, the beam adjustment control circuit 318 performs energization control corresponding to the beam arrangement for the high-speed inspection mode set for the beam regulator 28. , The beam adjuster 28 performs beam selection adjustment according to this energization control (step S4). Then, under the beam arrangement for the high-speed inspection mode, the pattern inspection device 1 performs the high-speed inspection (step S5).

On the other hand, as shown in FIG. 4, in the beam arrangement setting circuit 317, when the setting result of the inspection mode acquired from the control computer 31 is the high-sensitivity inspection mode (step S2: high sensitivity), the pre-set multi 2 It is determined whether or not the time has come to determine the deterioration of the secondary electron beam 300 (step S31).

When the time for determining deterioration has arrived (step S31: Yes), the beam arrangement setting circuit 317 causes the aberration detection circuit 315 to detect the aberration of the multi-secondary electron beam 300 for each secondary electron beam 301 (step S32). On the other hand, when the time for determining deterioration has not arrived (step S31: No), the beam arrangement setting circuit 317 has a beam arrangement that does not include the primary electron beam 201 on the outer peripheral portion as a beam arrangement for the normal high-sensitivity inspection mode. The arrangement is set (step S6).

After the aberration of the multi-secondary electron beam 300 is detected, the deterioration determination circuit 316 determines whether or not the multi-secondary electron beam 300 is deteriorated for each secondary electron beam 301 based on the detected aberration (step S33). ). At this time, the deterioration determination circuit 316 uses the primary electron beam 201 (the primary electron beam in the frame A in FIGS. 16 and 17 described later) excluding the primary electron beam 201 on the outer peripheral portion of the multi-primary electron beam 20. It is determined whether or not at least one secondary electron beam 301 corresponding to 201) is deteriorated.

When it is determined that at least one secondary electron beam 301 corresponding to the primary electron beam 201 excluding the primary electron beam 201 on the outer peripheral portion is deteriorated (step S33: Yes), the beam arrangement setting circuit 317 determines. The beam arrangement for high-sensitivity inspection according to the deterioration is set (step S34).

On the other hand, when it is determined that all the secondary electron beams 301 corresponding to the primary electron beam 201 except the primary electron beam 201 on the outer peripheral portion have not deteriorated (step S33: No), the beam arrangement setting circuit 317 , Set the beam arrangement for the normal high-precision inspection mode (step S6).

After the beam arrangement for the high-sensitivity inspection mode is set in step S34 or step S6, the beam adjustment control circuit 318 performs energization control corresponding to the beam arrangement for the high-sensitivity inspection mode set for the beam regulator 28. The beam adjuster 28 performs beam selection adjustment according to this energization control (step S7). Then, under the beam arrangement for the high-sensitivity inspection mode, the pattern inspection apparatus 1 carries out the high-sensitivity inspection (step S8).

<High-speed inspection mode>
Next, a specific example of the high-speed inspection mode will be described. FIG. 5 is a plan view showing a pattern inspection method according to the present embodiment. FIG. 6 is a plan view showing the beam arrangement, scanning region, and stripe of the multi-primary electron beam 20 in the high-speed inspection mode in the pattern inspection method according to the present embodiment.

In the high-speed inspection mode, the pattern inspection device 1 specifically operates as follows. First, in a state where the multi-primary electron beam 20 is focused on the reference position of the four surface of the substrate by the objective lens 212, the stage 225 on which the substrate 4 is placed by the drive mechanism 9 is placed under the control of the stage control circuit 36. Move it. Here, in the stage control circuit 36 and the deflection control circuit 310, as shown by the broken line arrow in FIG. 5, the stripe 42 in which the inspection area 41 of the substrate 4 to be inspected for the defect of the pattern is virtually divided into a plurality of strips is formed. The inspection region 41 is controlled to be scanned by the multi-primary electron beam 20 along the above. The stage control circuit 36 drives and controls the drive mechanism 9 so that the inspection region 41 is scanned by the multi-primary electron beam 20 along the stripe 42 (that is, along the x direction). The direction along the stripe 42 is the first movement direction of the stage 225, and the direction orthogonal to the stripe 42 is the second movement direction of the stage 225. As shown in FIG. 6, the stripe 42 is divided into scanning regions 43 corresponding to one irradiation (shot) of the multi-primary electron beam 20. The deflection control circuit 310 collectively deflects the entire multi-primary electron beam 20 for each of the plurality of scanning regions 43 constituting the stripe 42, and scans each scanning region 43 with the multi-primary electron beam 20. Controls 214. The movement of the stage 225 may be by a step-and-repeat method in which a settling time (that is, a waiting time for scanning) is taken until the stage position stabilizes each time the scanning area 43 is changed, or the scanning area 43 is changed. It may be a continuous movement method that does not take a settling time for each time.

FIG. 7 is a plan view showing scanning of the scanning region by the multi-primary electron beam in the high-speed inspection mode in the pattern inspection method according to the present embodiment. In FIG. 7, as all the primary electron beams 201 corresponding to the beam arrangement of the multi-primary electron beam 20 in the high-speed inspection mode, a multi composed of a total of 36 primary electron beams 201 in 6 rows × 6 columns. The primary electron beam 20 is shown.

The scanning area 43 is divided into a plurality of sub-scanning areas 44 that can be scanned by each of the primary electron beams 201. Each primary electron beam 201 scans the same position within the corresponding sub-scanning region 44. The scanning of the primary electron beam 201 for each sub-scanning region 44 is performed by the collective deflection of the entire multi-primary electron beam 20 by the objective deflector 214 as described above.

In the batch deflection of the multi-primary electron beams 20 by the objective deflector 214, the moving direction and the moving amount of each primary electron beam 201 are the same. As a result, the multi-primary electron beam 20 always maintains a state of being arranged in a square grid pattern. In other words, the y-coordinates of the adjacent primary electron beams 201 in the x-direction are kept the same, and the x-coordinates of the adjacent primary electron beams 201 in the y-direction are kept the same.

Further, the multi-primary electron beam 20 has a rectangular shape when viewed as a whole of the multi-primary electron beam 20. By scanning the entire corresponding sub-scanning region 44 by each primary electron beam 201 constituting such a multi-primary electron beam 20, the entire scanning region 43 is scanned. Then, this scan is repeated for all scan regions 43 on the stripe 42 while moving the stage 225.

According to the multi-primary electron beam 20 having such a beam arrangement in the high-speed inspection mode, as shown in FIG. 6, it is possible to scan the entire scanning region 43 that fills the inspection region 41 without duplication and gaps. As a result, the inspection area 41 can be scanned in excess or deficiency. Further, by using all the primary electron beams 201, the inspection can be performed quickly.

Due to the fact that the multi-primary electron beam 20 arranged as described above is irradiated to a desired position on the substrate 4, the multi-secondary containing the backscattered electrons corresponding to the multi-primary electron beam 20 from the substrate 4 The electron beam 300 is emitted. The multi-secondary electron beam 300 emitted from the substrate 4 advances to the beam separator 216 and is bent obliquely upward. The multi-secondary electron beam 300 bent diagonally upward is bent by the bender 217 and projected onto the multi-detector 224. The multi-detector 224 detects the projected multi-secondary electron beam 300 as two-dimensional electron image data. The detected two-dimensional electronic image data is output to the detection circuit 6 in the order of detection. In the detection circuit 6, analog two-dimensional electronic image data is converted into digital data by an A / D converter (not shown) and stored in the pattern memory 7.

In this way, the pattern inspection device 1 acquires the two-dimensional electronic image data of the pattern formed on the substrate 4 as the image data to be inspected. The acquired image data to be inspected is transferred to the comparison circuit 34 together with information indicating each position from the position detection circuit 33. The comparison circuit 34 temporarily stores the transferred image data to be inspected.

Next, the reference image creation circuit 35 creates a reference image corresponding to the image to be inspected. Specifically, the reference image creation circuit 35 reads out the design data that is the basis for forming the pattern on the substrate 4 from the storage device 311 and converts the read design data into binary or multi-valued image data. , The reference image data is created by applying appropriate filtering to the converted image data. Then, the reference image creation circuit 35 outputs the created reference image data to the comparison circuit 34. The comparison circuit 34 temporarily stores the output reference image data.

Next, the comparison circuit 34 reads out the stored image data to be inspected and the reference image data, and aligns both image data. After the alignment, the comparison circuit 34 determines the presence or absence of a defect such as a shape defect by comparing the aligned image data to be inspected with the reference image data. For example, the comparison circuit 34 determines that a defect is found if the gradation value difference between the image data to be inspected and the reference image data is larger than the determination threshold value, and outputs the determination result to the storage device 311, the monitor 312, the memory 313, or the printer 314. To do. In this way, the inspection in the high speed inspection mode is performed.

<High sensitivity inspection mode>
Next, a specific example of the high-sensitivity inspection mode will be described. In the high-sensitivity inspection, the moving method of the stage 255 and the deflection method of the multi-primary electron beam 20 are basically the same as those of the high-speed inspection described above. Therefore, the differences from the high-speed inspection will be mainly described below. ..

FIG. 8 is a plan view showing scanning of a scanning region by a multi-primary electron beam in a high-sensitivity inspection mode in the pattern inspection method according to the present embodiment. FIG. 8 shows the multi 1 composed of a total of 16 primary electron beams 201 in 4 rows × 4 columns as the primary electron beam 201 corresponding to the beam arrangement of the multi primary electron beam 20 in the high sensitivity inspection mode. The next electron beam 20 is shown. The multi-primary electron beam 20 corresponds to the primary electron beam 201 in the frame A of FIG. 6 in which the primary electron beam 201 on the outer peripheral portion is excluded from the high-speed inspection mode shown in FIG. The multi-primary electron beam 20 in such a high-sensitivity inspection mode is a rectangular multi-primary electron beam 20 as a whole, like the multi-primary electron beam 20 in the high-speed inspection mode.

According to the multi-primary electron beam 20 having such a high-sensitivity inspection mode beam arrangement, as shown in FIG. 8, it is possible to scan the entire scanning region 43 that fills the inspection region 41 without duplication and gaps. .. As a result, the inspection area 41 can be scanned in excess or deficiency. Further, by using the primary electron beam 201 excluding the outer peripheral portion, the inspection can be performed with high accuracy even when the primary electron beam 201 on the outer peripheral portion is deteriorated.

<Maintenance mode>
Next, a specific example of the maintenance mode will be described. FIG. 9 is a plan view showing a beam arrangement according to beam deterioration in the maintenance mode in the pattern inspection method according to the present embodiment. FIG. 12 is a plan view showing the beam arrangement, the scanning area, and the stripe in the maintenance mode in the pattern inspection method according to the present embodiment. FIG. 13 is an explanatory diagram for explaining the beam arrangement in the pattern inspection method according to the present embodiment.

In FIG. 9, as an example of a specific beam arrangement in the maintenance mode, an example of the beam arrangement according to the deterioration of the multi-secondary electron beam 300 is shown by the sub-scanning region 44. In FIG. 9, the black-painted rectangular region is a deteriorated region where the corresponding secondary electron beam 301 is determined to be deteriorated, and the primary electron beam 201, that is, the sub-scanning region 44 is arranged in this deteriorated region. This is the area to be invalidated without using it. The hatched rectangular region is a region where it is determined that the corresponding secondary electron beam 301 has not deteriorated, but is intentionally invalidated in order to form a specific beam arrangement. The white rectangular region 44 is a sub-scanning region 44 in which the primary electron beam 201 is arranged, and the scanning region 43, which is a set of the sub-scanning regions 44, is formed on the secondary electron beam 301 determined to be deteriorated. It corresponds to a specific beam arrangement that does not include the corresponding primary electron beam 201 and can scan the inspection area 41 of the substrate 4 in just proportion.

The specific beam arrangement is a square grid-like beam arrangement along the first moving direction (that is, x direction) of the stage 225 and the second moving direction (that is, y direction) of the stage 225 that is orthogonal to the first moving direction. In a beam arrangement in which the primary electron beams 201 at the four corners including the primary electron beam 201 corresponding to the secondary electron beam 301 determined to be deteriorated when viewed as a whole of the multi-primary electron beam 20 are missing. is there. In other words, a rectangular area surrounded by a line segment circumscribing the sub-scanning areas 44 at both ends in the x direction along the y direction and a line segment circumscribing the sub-scanning areas 44 at both ends in the y direction along the x direction ( The beam 201, that is, the scanning region 43 is not arranged at the four corners (see the broken line portion in FIG. 9).

As shown in FIG. 12, the stripe 42 corresponding to FIG. 9 has a shape whose width varies periodically. In other words, in the stripe 42 of FIG. 12, both ends of the stripe 42 in the second moving direction (that is, the y direction) are periodically in the second moving direction of the stripe 42 along the first moving direction (that is, the x direction). It has a shape in which approaching and separating from the center C of the above are alternately repeated (that is, the stripe width is alternately decreased and increased).

As shown in FIG. 12, the stripes 42 adjacent to each other in the second moving direction have the same period in which both ends of the stripes 42 in the second moving direction repeatedly approach and separate from each other, but the approach and separation are the same. The positions at which the above starts are arranged so as to deviate from each other in the first movement direction. That is, when it is considered that the stripes 42 extend in the first movement direction (x direction) (horizontally long) as shown in FIG. 12, the stripes 42 adjacent to each other in the second movement direction (y direction) are the second. The cycle and shape of the fluctuation in the second movement direction of one end (upper end) in the two movement directions and the other end (lower end) in the second movement direction are the same, and have a shape that is out of phase. Further, the stripes 42 adjacent to each other in the second moving direction are arranged so that the pitch, which is the distance between the centers C, is smaller than the maximum width of the stripes 42. That is, the stripes 24 adjacent to each other in the second moving direction are arranged so as to spread the inspection area 41 without gaps and overlaps. That is, the inspection area 41 has a shape without a gap.

More specifically, as shown in FIG. 13, the specific beam arrangement in the maintenance mode is a beam arrangement in which the sum of the number of beams in the K line and the number of beams in the NA + K line is M.

However, the row direction in the arrangement of the multi-primary electron beam 20 is the first moving direction of the stage 225, that is, the direction parallel to the x direction. Further, the row direction in the arrangement of the multi-primary electron beam 20 is a direction parallel to the second moving direction of the stage 225, that is, the y direction. Further, M is the number of columns of the primary electron beam 201 constituting the multi-primary electron beam 20, and in the example of FIG. 13, M is 6. Further, N is the number of rows of the primary electron beam 201 constituting the multi-primary electron beam 20, and in the example of FIG. 13, N is 6. Further, A is 1/2 of the number of rows in which the number of beams in the column direction is smaller than M, and in the example of FIG. 13, A is 2. Further, K is an arbitrary integer of 1 or more and A or less, and in the example of FIG. 13, K is 1 or 2.

More specifically, as shown in FIG. 13, the sum of two beams, which is K = the number of beams in the first row, and four beams, which is NA + K = (6-2 + 1) = the number of beams in the fifth row, is There are 6 or M. The sum of 4 beams, which is the number of beams in the second row of K =, and 2 beams, which is the number of beams in the 6th row of NA + K = (6-2 + 2), is 6.

Further, in the example of FIG. 13, the multi-primary electron beam 20 has an even number of beams of the primary electron beam 201 in the column direction and the row direction, and is arranged so as to be rotationally symmetric by 180 °. ..

According to the multi-primary electron beam 20 arranged as shown in FIG. 13, as shown in FIG. 12, it is possible to scan the entire scanning region 43 that fills the inspection region 41 without duplication and gaps. As a result, the inspection area 41 can be scanned in excess or deficiency, so that the accuracy and efficiency of the inspection can be improved.

As shown in FIG. 12, the scanning area 43 is displaced in the x direction between the adjacent stripes 42 in the y direction so that the scanning area 43 fills the inspection area 41. The process of shifting the position of the scanning region 43 in the x direction in this way can be performed, for example, by shifting the stage position. For example, in the step-and-repeat method, scanning is started at a position where the stage 225 is shifted, and in the case of the continuous movement method, the position in the x direction of the scanning area 43 is adjusted by shifting the timing at which scanning is started. be able to.

The specific beam arrangement in the maintenance mode is not limited to the example of FIG. For example, when considering the beam arrangement including the maximum number of primary electron beams 201 without including the primary electron beam 201 corresponding to the secondary electron beam 301 determined to be deteriorated, as shown in FIG. The movement of the stage 225 is simpler if it is made into a simple rectangular shape with one less line in the Y direction, there is no processing such as periodic phase shift, and the processing is not complicated. Further, as shown in FIG. 11, in the case of a simple rectangular shape having one row less in the X direction, scanning can be performed without gaps and overlaps by finely adjusting the speed of movement in the stripe direction.

FIG. 14 is a plan view showing a beam arrangement according to beam deterioration different from that in FIG. 9 in the maintenance mode in the pattern inspection method according to the present embodiment. The specific beam arrangement for the maintenance mode is not fixed to the beam arrangement shown in FIG. 9, and may be changed according to the mode of deterioration of the multi-secondary electron beam 300, for example, as shown in FIG. it can.

As described above, according to the present embodiment, the aberration of the multi-secondary electron beam 300 is detected for each secondary electron beam 301, and the presence or absence of deterioration of the multi-secondary electron beam 300 is determined based on the detected aberration. It can be determined for each secondary electron beam 301. Then, the multi-primary arrangement is such that the primary electron beam 201 corresponding to the secondary electron beam 301 determined to be deteriorated is not included and the inspection region 41 of the substrate 4 can be scanned without excess or deficiency. The beam arrangement of the electron beam 20 can be controlled. As a result, even if the multi-primary electron beam 20 is partially deteriorated, the inspection area 41 can be scanned without excess or deficiency by the undamaged multi-primary electron beam 20, so that it is good regardless of the deterioration of the beam. Inspection can be performed with high accuracy and efficiency.

Further, according to the present embodiment, the beam arrangement is a square grid along the first moving direction and the second moving direction of the stage 225 on which the substrate 4 is placed, and the multi-primary electron beam 20 is viewed as a whole. By using a beam arrangement in which the primary electron beams 201 at the four corners including the primary electron beam 201 corresponding to the secondary electron beam 301 determined to be deteriorated are missing, the multi-primary beam is not deteriorated. The electron beam 20 can scan the entire scanning region 43 that fills the inspection region 41 without overlap and gaps. As a result, the inspection area 41 can be scanned without excess or deficiency, so that the accuracy and efficiency of the inspection can be improved.

Further, according to the present embodiment, the multi-primary electron beam 20 is arranged so that the sum of the number of beams in the Kth row and the number of beams in the NA + Kth row is M, so that the inspection area is inspected. It is possible to reliably scan the entire scanning region 43 that fills 41 with no overlap and gaps.

Further, according to the present embodiment, a specific beam arrangement is set when the maintenance mode is set, and a beam arrangement including all primary electron beams 201 is set when the high-speed inspection mode is set, and the height is high. When the sensitivity inspection mode is set, by setting the beam arrangement that does not include the primary electron beam 201 on the outer peripheral portion, it is possible to set a suitable beam arrangement according to the inspection mode.

Further, according to the present embodiment, at least one of the focal point and the directivity of the multi-primary electron beam 20 is adjusted for each primary electron beam 201 by the beam regulator 28, so that the beam arrangement of the multi-primary electron beam 20 is performed. Can be controlled appropriately.

Further, according to the present embodiment, it is possible to easily and surely determine whether or not the multi-secondary electron beam 300 is deteriorated based on whether or not the aberration of the multi-secondary electron beam 300 is larger than the allowable value.
Further, according to the present embodiment, the multi-primary electron beam 20 can be easily arranged by arranging the multi-primary electron beam 20 so as to be rotationally symmetric by 180 °.

<High-speed inspection mode according to beam deterioration>
Next, a specific example of the high-speed inspection mode according to the deterioration of the multi-secondary electron beam 300 will be described. FIG. 15 is a plan view showing a beam arrangement in a high-speed inspection mode according to beam deterioration in the pattern inspection method of FIG. As shown in FIG. 15, when it is determined that at least one secondary electron beam 301 is deteriorated (step S23: Yes), the beam arrangement setting circuit 317 determines that the secondary electron beam is deteriorated. A beam arrangement is set that does not include the primary electron beam 201 corresponding to the beam 301 and can scan the inspection area 41 of the substrate 4 without excess or deficiency, and includes the maximum number of primary electron beams 201.

In this way, by performing the high-speed inspection according to the deterioration of the beam, it is possible to perform the high-speed inspection with good accuracy and efficiency regardless of the deterioration of the beam.

<High-sensitivity inspection mode according to beam deterioration>
Next, a specific example of the high-sensitivity inspection according to the deterioration of the multi-secondary electron beam 300 will be described. FIG. 16 is a plan view showing a beam arrangement in a high-sensitivity inspection mode according to beam deterioration in the pattern inspection method of FIG. FIG. 17 is a plan view showing a different beam arrangement from that of FIG. 16 in the high-sensitivity inspection mode according to the beam deterioration in the pattern inspection method of FIG. For example, as illustrated in FIGS. 16 and 17, when the beam arrangement setting circuit 317 determines that at least one secondary electron beam 301 corresponding to the primary electron beam 201 in the frame A has deteriorated ( Step S33: Yes) in FIG. 4, the beam arrangement does not include the primary electron beam 201 in the outer peripheral portion, and does not include the primary electron beam 201 corresponding to the secondary electron beam 301 determined to be deteriorated. Set the beam arrangement. As shown in FIG. 16, even in a high-sensitivity inspection, it is preferable that the effective area is as wide as possible from the viewpoint of inspection efficiency.

By performing the high-sensitivity inspection according to the deterioration of the beam in this way, the inspection can be performed with good accuracy and efficiency regardless of the deterioration of the beam.

(Modified example of beam arrangement)
Next, a modification of the arrangement of the multi-primary electron beam 20 will be described. 18 (A) to 18 (K) are plan views showing a modified example of the arrangement of the multi-primary electron beam 20. In addition, in FIGS. 18A to 18K, the arrangement of the multi-primary electron beam 20 is shown as the arrangement of the sub-scanning region 44. Although not shown, each sub-scanning region 44 is assigned a corresponding beam 201 of the multi-primary electron beams 20.

In FIG. 12, a total of 24 multi-primary electron beams 20 have been described, but the number of beams of the multi-primary electron beam 20 is a scanning region 43 in which the inspection region 41 is filled with the multi-primary electron beam 20 without duplication and gaps. The number is not limited to 24 as long as the entire image can be scanned.

For example, as shown in FIGS. 18A to 18C, the number of beams of the multi-primary electron beam 20 may be 40. In 2 * SQRT (12.5) shown in FIG. 18 (A), the distance between the farthest beams indicated by the bidirectional arrows in FIG. 18 (A) is the length of one side of the square sub-scanning region 44. Is shown as a relative value when 1 is set (hereinafter, the same applies). The larger this distance, the larger the field of view (FOV). In the examples of FIGS. 18 (B) and 18 (C), the distance between the farthest beams is 2 * SQRT (13.5), so that in FIG. 18 (A), FIG. 18 (B), The field of view is smaller than that of FIG. 916 (C).

The number of beams of the multi-primary electron beam 20 may be 60 as shown in FIGS. 18 (D) to 18 (F), or 80 as shown in FIG. 18 (G). It may be 90 as shown in FIG. 18 (H), or may be 100 as shown in FIG. 18 (I). Alternatively, the number of beams of the multi-primary electron beam 20 may be 96 as shown in FIG. 18 (J) or 108 as shown in FIG. 18 (K).

FIG. 19 is a plan view showing still another modification of the arrangement of the multi-primary electron beam 20. Further, as shown in FIG. 19, if the multi-primary electron beam 20 can scan the entire scanning region 43 that fills the inspection region 41 without overlap and gaps, the multi-primary electron beam 20 should not be 180 ° rotationally symmetric. It may be arranged.

(Modification example of pattern inspection device)
FIG. 20 is a diagram showing a pattern inspection device according to a modification of the present embodiment. So far, an example in which a specific beam arrangement of the multi-primary electron beam 20 is formed by adjusting the focal point and the directivity of the multi-primary electron beam 20 by the beam regulator 28 has been described. On the other hand, as shown in FIG. 20, the pattern inspection device 1 may form a specific arrangement by having the aperture array substrate 25 provided with holes 251 of the arrangement corresponding to the specific beam arrangement. Good. The aperture array substrate 25 in FIG. 20 has an aperture array unit 250A used for high-speed inspection, an aperture array unit 250B used for high-sensitivity inspection, and an aperture array unit 250C used for maintenance inspection. The moving mechanism 252 configured by the actuator selectively moves the aperture array units 250A to 250C according to the inspection mode set by the control computer 31 on the optical path of the electron beam 200.

According to this modification, the arrangement of the multi-primary electron beam 20 capable of scanning the inspection region 41 in excess or deficiency can be easily realized by arranging the holes 251 of the aperture array substrate 25.

At least a part of the pattern inspection device 1 may be configured by hardware or software. When configured by software, a program that realizes at least a part of the functions of the pattern inspection device 1 may be stored in a recording medium such as a flexible disk or a CD-ROM, read by a computer, and executed. The recording medium is not limited to a removable one such as a magnetic disk or an optical disk, and may be a fixed recording medium such as a hard disk device or a memory.

The above embodiments are presented as examples and are not intended to limit the scope of the invention. The embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

1 Pattern inspection device 28 Beam adjuster 315 Aberration detection circuit 316 Deterioration judgment circuit 317 Beam arrangement setting circuit 318 Beam adjustment control circuit 4 Board

Claims (4)

A multi-electron beam image acquisition device that irradiates a substrate with a multi-primary electron beam and acquires an image of the multi-secondary electron beam emitted from the substrate.
An aberration detection unit that detects the aberration of the multi-secondary electron beam, and
A deterioration determination unit that determines whether or not the multi-secondary electron beam is deteriorated based on the detected aberration, and a deterioration determination unit.
The beam of the multi-primary electron beam does not include the primary electron beam corresponding to the secondary electron beam determined to be deteriorated, and has a specific beam arrangement capable of scanning the inspection area of the substrate without excess or deficiency. A multi-electron beam image acquisition device including a beam arrangement control unit for controlling arrangement. The specific beam arrangement is a square grid-like beam arrangement along a first moving direction of the stage on which the substrate is placed and a second moving direction orthogonal to the first moving direction, and is the multi-primary. The first aspect of claim 1, wherein the primary electron beams at the four corners including the primary electron beam corresponding to the secondary electron beam determined to be deteriorated when viewed as the entire electron beam are missing. Multi-electron beam image acquisition device. In the square grid-like beam arrangement, when the first moving direction is the column direction and the second moving direction is the row direction, the sum of the number of beams in the K row and the number of beams in the NA + K row is The multi-electron beam image acquisition device according to claim 2, which has M beam arrangements.
However,
M: Number of columns of primary electron beams constituting the multi-primary electron beam N: Number of rows of primary electron beams constituting the multi-primary electron beam A: Number of rows in which the number of beams in the column direction is less than M 1/2
K: Any integer greater than or equal to 1 and less than or equal to A The beam arrangement control unit
When the first inspection mode for inspecting the substrate in consideration of the deterioration state of the multi-secondary electron beam is set, the beam arrangement of the multi-primary electron beam is controlled so as to have the specific beam arrangement. And
When the second inspection mode for carrying out the inspection that prioritizes the inspection speed is set, the beam arrangement of the multi-primary electron beam is controlled so that the beam arrangement includes all the primary electron beams.
When the third inspection mode for carrying out the inspection that gives priority to the inspection sensitivity is set, the beam arrangement of the multi-primary electron beam is controlled so that the beam arrangement does not include the primary electron beam on the outer peripheral portion. The multi-electron beam image acquisition device according to any one of claims 1 to 3.

Images