JP2022163680A - Multi electron beam image acquisition method, multi electron beam image acquisition device, and multi electron beam inspection device - Google Patents

Abstract

To provide a method of canceling positional movement of a multi secondary electron beam accompanying scanning of a multi primary electron beam.SOLUTION: A representative primary electron beam selected from a multi primary electron beam is irradiated onto a plurality of positions within a preset deflection range, and a representative secondary electron beam emitted from each of the plurality of positions within a representative primary beam deflection range is scanned under a temporary secondary beam deflection condition, and a plurality of coordinates corresponding to the plurality of positions are obtained on the basis of the detected image of the representative secondary electron beam detected by a predetermined detection element of a multi-detector, and a secondary beam deflection condition is calculated such that the movement of the representative secondary electron beam caused by the movement of the representative primary electron beam within the range of deflection of the primary beam is cancelled using the obtained plurality of coordinates.SELECTED DRAWING: Figure 6

Description

Embodiments of the present invention relate to a multi-electron-beam image acquisition method, a multi-electron-beam image acquisition apparatus, and a multi-electron-beam inspection apparatus, in which a substrate is irradiated with multiple primary electron beams, and multiple secondary electrons are emitted from the substrate. The present invention relates to a technique for detecting beams and obtaining images.

2. Description of the Related Art In recent years, as large-scale integrated circuits (LSIs) have become highly integrated and have large capacities, the circuit line width required for semiconductor elements has become increasingly narrow. In addition, the improvement of yield is essential for the manufacture of LSIs, which requires a great manufacturing cost. However, as typified by 1-gigabit-class DRAMs (random access memories), patterns forming LSIs are on the order of submicrons to nanometers. In recent years, as the dimensions of LSI patterns formed on semiconductor wafers have become finer, the dimensions that must be detected as pattern defects have become extremely small. Therefore, there is a need to improve the precision of a pattern inspection apparatus for inspecting defects in an ultrafine pattern transferred onto a semiconductor wafer. In addition, one of the major factors that lower the yield is the pattern defect of the mask used when exposing and transferring the ultra-fine pattern onto the semiconductor wafer by photolithography technology. Therefore, it is necessary to improve the precision of pattern inspection apparatuses for inspecting defects in transfer masks used in LSI manufacturing.

The inspection apparatus, for example, irradiates a substrate to be inspected with multiple beams using electron beams, detects secondary electrons corresponding to each beam emitted from the substrate to be inspected, and picks up a pattern image. Then, there is known a method of performing an inspection by comparing the captured measurement image with design data or a measurement image of the same pattern on the substrate. For example, "die to die inspection" that compares measurement image data obtained by imaging the same pattern at different locations on the same substrate, and design image data (reference image) based on pattern design data and compare it with a measurement image, which is the measurement data of the pattern captured. The captured image is sent to the comparison circuit as measurement data. After aligning the images, the comparison circuit compares the measurement data with the reference data according to an appropriate algorithm, and determines that there is a pattern defect if they do not match.

When imaging using multiple beams, a predetermined range is scanned with multiple primary electron beams. Therefore, the emission position of each secondary electron beam changes every moment. In order to irradiate the corresponding detection regions of the multi-detector with the secondary electron beams whose emission positions have changed, it is necessary to deflect the positional movement of the multi-secondary electron beams caused by the changes in the emission positions. .

Although it is not a multi-beam electron microscope, the sample is scanned with an electron beam, and the electron beam that has passed through the sample is deflected by a deflection coil and then detected by a detector. It is disclosed that the swing-back amount of the swing-back coil is calculated from the amount of change in an image captured in advance by a camera different from the detector (see, for example, Patent Document 1). Such a method has the problem of requiring a high-resolution imaging element separate from the detector for acquiring the image. Therefore, it becomes necessary to install two types of detectors, which leads to an increase in size and cost of the apparatus. In addition, the accuracy of adjustment may become insufficient.

Japanese Patent Application Laid-Open No. 2006-196236

In an embodiment of the present invention, multiple secondary electron beams that compensate for the positional movement of the multiple secondary electron beams accompanying the scanning of the multiple primary electron beams without using a measuring means separate from the detector for capturing an image. An apparatus and method capable of acquiring an image with beam deflection adjustment are provided.

A multi-electron beam image acquisition method according to one aspect of the present invention comprises:
a step of irradiating a representative primary electron beam selected from the multiple primary electron beams onto a plurality of positions within a preset primary beam deflection range on a stage on which the substrate is placed;
a step of scanning, for each of a plurality of positions in a representative primary beam deflection range, a representative secondary electron beam emitted from the position due to irradiation of the representative primary electron beam under a temporary secondary beam deflection condition; ,
A step of detecting a representative secondary electron beam scanned under a temporary secondary beam deflection condition with predetermined detection elements of a multi-detector having a plurality of detection elements for each of a plurality of positions in a representative primary beam deflection range. When,
a step of acquiring a plurality of coordinates corresponding to a plurality of positions based on the detected image of the representative secondary electron beam detected for each of the plurality of positions in the primary beam deflection range;
Using the acquired plurality of coordinates, the movement of the representative secondary electron beam due to the movement of the representative primary electron beam within the primary beam deflection range is offset, and the representative secondary electron beam is directed to the predetermined detection element. calculating the secondary beam deflection condition so that the irradiation position of is fixed;
The substrate placed on the stage is scanned using the multiple primary electron beams within the primary electron beam deflection range, and the multiple secondary electron beams emitted from the substrate are deflected according to the calculated secondary beam deflection conditions. obtaining a secondary electron image of the substrate by detecting the multi-secondary electron beams with a multi-detector while scanning the secondary electron beams;
characterized by comprising

Moreover, it is preferable to use four corner positions of the primary electron beam deflection range as the plurality of positions.

Moreover, it is preferable that the deflection conditions of the secondary electron beam include a deflection magnification and a deflection rotation angle.

Also, it is preferable to use the central beam of the multiple primary electron beams as the representative primary electron beam.

Alternatively, using beams at four corners of a multi-primary electron beam as representative primary electron beams,
It is preferable that the secondary beam deflection conditions are calculated for each of the four corner beams and statistical values of the values calculated for each beam are used.

The method further comprises a step of synthesizing detection images of representative secondary electron beams detected for each of a plurality of positions in the primary beam deflection range,
Preferably, the multiple coordinates are obtained using the combined composite image.

A multi-electron beam image acquisition device according to one aspect of the present invention comprises:
a stage on which the substrate is placed;
a primary system deflector that irradiates a representative primary electron beam selected from the multiple primary electron beams onto a plurality of positions within a preset primary beam deflection range on the stage;
A secondary scan for each position of a plurality of positions in a representative primary beam deflection range under a temporary secondary beam deflection condition with a representative secondary electron beam emitted from the position due to the irradiation of the representative primary electron beam. a system deflector;
a representative secondary electron beam scanned under a temporary secondary beam deflection condition at each position of a plurality of positions in a representative primary beam deflection range, with predetermined detecting elements of the plurality of detecting elements; a multi-detector for detecting;
a coordinate acquisition unit that acquires a plurality of coordinates corresponding to a plurality of positions based on the detected image of the representative secondary electron beam detected for each of the plurality of positions in the primary beam deflection range;
Using the acquired plurality of coordinates, the movement of the representative secondary electron beam due to the movement of the representative primary electron beam within the primary beam deflection range is offset, and the representative secondary electron beam is directed to the predetermined detection element. a deflection condition calculation unit for calculating a secondary beam deflection condition so that the irradiation position of is fixed;
with
The substrate placed on the stage is scanned by the primary system deflector using multiple primary electron beams within the primary electron beam deflection range, and the secondary system is deflected according to the calculated secondary beam deflection conditions. A secondary electron image of the substrate is acquired by detecting the multiple secondary electron beams with a multiple detector while scanning the multiple secondary electron beams emitted from the substrate by beam deflection by a detector.

A multi-electron beam inspection apparatus according to one aspect of the present invention includes
a stage on which the substrate is placed;
a primary system deflector that irradiates a representative primary electron beam selected from the multiple primary electron beams onto a plurality of positions within a preset primary beam deflection range on the stage;
A secondary scan for each position of a plurality of positions in a representative primary beam deflection range under a temporary secondary beam deflection condition with a representative secondary electron beam emitted from the position due to the irradiation of the representative primary electron beam. a system deflector;
a representative secondary electron beam scanned under a temporary secondary beam deflection condition at each position of a plurality of positions in a representative primary beam deflection range, with predetermined detecting elements of the plurality of detecting elements; a multi-detector for detecting;
a coordinate acquisition unit that acquires a plurality of coordinates corresponding to a plurality of positions based on the detected image of the representative secondary electron beam detected for each of the plurality of positions in the primary beam deflection range;
Using the acquired plurality of coordinates, the movement of the representative secondary electron beam due to the movement of the representative primary electron beam within the primary beam deflection range is offset, and the representative secondary electron beam is directed to the predetermined detection element. a deflection condition calculation unit for calculating a secondary beam deflection condition so that the irradiation position of is fixed;
with
The substrate placed on the stage is scanned by the primary system deflector using multiple primary electron beams within the primary electron beam deflection range, and the secondary system is deflected according to the calculated secondary beam deflection conditions. acquiring a secondary electron image of the substrate by detecting the multiple secondary electron beams with the multiple detector while scanning the multiple secondary electron beams emitted from the substrate by beam deflection by the detector;
It is characterized by further comprising a comparison unit that compares at least part of the obtained secondary electron image with a predetermined image.

A multi-electron beam image acquisition device according to another aspect of the present invention comprises:
a stage on which the substrate is placed;
a primary system deflector for sequentially irradiating representative primary electron beams representing the multiple primary electron beams onto a plurality of positions within a primary beam deflection range set in advance on the stage at different times;
A secondary scan for each position of a plurality of positions in a representative primary beam deflection range under a temporary secondary beam deflection condition with a representative secondary electron beam emitted from the position due to the irradiation of the representative primary electron beam. a system deflector;
a representative secondary electron beam scanned under a temporary secondary beam deflection condition at each position of a plurality of positions in a representative primary beam deflection range, with predetermined detecting elements of the plurality of detecting elements; a multi-detector for detecting;
an image synthesizing unit for synthesizing detection images of representative secondary electron beams detected for each of a plurality of positions in a primary beam deflection range;
The synthesized composite image is used to cancel the representative secondary electron beam movement due to the representative primary electron beam movement within the primary beam deflection range, and the representative secondary electron beam to the predetermined detector element. a deflection condition calculation unit that calculates a secondary beam deflection condition so that the irradiation position is fixed;
with
The substrate placed on the stage is scanned by the primary system deflector using multiple primary electron beams within the primary electron beam deflection range, and the secondary system is deflected according to the calculated secondary beam deflection conditions. A secondary electron image of the substrate is acquired by detecting the multiple secondary electron beams with the multiple detector while scanning the multiple secondary electron beams emitted from the substrate by beam deflection by the detector.

A multi-electron beam inspection apparatus according to another aspect of the present invention comprises:
a stage on which the substrate is placed;
a primary system deflector for sequentially irradiating representative primary electron beams representing the multiple primary electron beams onto a plurality of positions within a primary beam deflection range set in advance on the stage at different times;
A secondary scan for each position of a plurality of positions in a representative primary beam deflection range under a temporary secondary beam deflection condition with a representative secondary electron beam emitted from the position due to the irradiation of the representative primary electron beam. a system deflector;
a representative secondary electron beam scanned under a temporary secondary beam deflection condition at each position of a plurality of positions in a representative primary beam deflection range, with predetermined detecting elements of the plurality of detecting elements; a multi-detector for detecting;
an image synthesizing unit for synthesizing detection images of representative secondary electron beams detected for each of a plurality of positions in a primary beam deflection range;
The synthesized composite image is used to cancel the representative secondary electron beam movement due to the representative primary electron beam movement within the primary beam deflection range, and the representative secondary electron beam to the predetermined detector element. a deflection condition calculation unit that calculates a secondary beam deflection condition so that the irradiation position is fixed;
with
The substrate placed on the stage is scanned by the primary system deflector using multiple primary electron beams within the primary electron beam deflection range, and the secondary system is deflected according to the calculated secondary beam deflection conditions. acquiring a secondary electron image of the substrate by detecting the multiple secondary electron beams with the multiple detector while scanning the multiple secondary electron beams emitted from the substrate by beam deflection by the detector;
It is characterized by further comprising a comparison unit that compares at least part of the obtained secondary electron image with a predetermined image.

According to one aspect of the present invention, there is provided a multi-secondary electron beam detector that offsets the positional movement of the multi-secondary electron beams accompanying the scanning of the multi-primary electron beams without using a measuring means separate from a detector for capturing an image. An image in which the deflection of the next electron beam is adjusted can be obtained.

1 is a configuration diagram showing the configuration of an inspection apparatus according to Embodiment 1; FIG. FIG. 2 is a conceptual diagram showing the configuration of a shaping aperture array substrate according to Embodiment 1; 4 is a diagram showing an example of a plurality of chip regions formed on the semiconductor substrate according to Embodiment 1; FIG. 4 is a diagram for explaining inspection processing in the first embodiment; FIG. 3 is a diagram showing an example of an internal configuration of a deflection adjustment circuit according to Embodiment 1; FIG. FIG. 2 is a flow chart diagram showing an example of essential steps of an inspection method according to Embodiment 1; FIG. 4 is a diagram for explaining how beams are selected according to the first embodiment; FIG. 4 is a diagram for explaining the position of a representative secondary electron beam when the representative primary electron beam is applied to the scanning center of the scanning range of the primary electron beam in Embodiment 1. FIG. FIG. 4 is a diagram for explaining an example of the position of a representative secondary electron beam when the representative primary electron beam is applied to the lower left corner position of the scanning range of the primary electron beam in Embodiment 1; FIG. 4 is a diagram for explaining an example of the position of a representative secondary electron beam when the representative primary electron beam is applied to the lower right corner position of the scanning range of the primary electron beam in Embodiment 1; FIG. 4 is a diagram for explaining an example of the position of a representative secondary electron beam when the upper right corner position of the scanning range of the primary electron beam is irradiated with the representative primary electron beam in Embodiment 1; FIG. 4 is a diagram for explaining an example of the position of a representative secondary electron beam when the upper left corner position of the scanning range of the primary electron beam is irradiated with the representative primary electron beam in Embodiment 1; 4 is a diagram showing an example of a composite image according to Embodiment 1; FIG. 4 is a diagram showing an example of a relative relationship between a primary beam scanning range and a secondary beam scanning range in Embodiment 1. FIG. FIG. 10 is a diagram showing an example of a synthesized image after adjustment according to Embodiment 1; FIG. FIG. 2 is a configuration diagram showing an example of the internal configuration of a comparison circuit according to the first embodiment; FIG. FIG. 10 is a diagram for explaining a representative primary electron beam in Embodiment 2; FIG. 10 is a diagram for explaining an example of the position of a representative secondary electron beam when the representative primary electron beam is applied to the lower left corner position of the scanning range of the primary electron beam in Embodiment 2; FIG. 10 is a diagram for explaining an example of the position of a representative secondary electron beam when the representative primary electron beam is applied to the lower right corner position of the scanning range of the primary electron beam in Embodiment 2; FIG. 10 is a diagram for explaining an example of the position of a representative secondary electron beam when the upper left corner position of the scanning range of the primary electron beam is irradiated with the representative primary electron beam in Embodiment 2; FIG. 10 is a diagram for explaining an example of the position of a representative secondary electron beam when the upper right corner position of the scanning range of the primary electron beam is irradiated with the representative primary electron beam in Embodiment 2;

In the following embodiments, an inspection apparatus using multiple electron beams will be described as an example of a multiple electron beam image acquisition apparatus. However, it is not limited to this. Any apparatus may be used as long as it irradiates multiple primary electron beams and obtains an image using multiple secondary electron beams emitted from the substrate.

Embodiment 1.
FIG. 1 is a configuration diagram showing the configuration of an inspection apparatus according to Embodiment 1. FIG. In FIG. 1, an inspection apparatus 100 for inspecting a pattern formed on a substrate is an example of a multi-electron beam inspection apparatus. The inspection apparatus 100 has an image acquisition mechanism 150 and a control system circuit 160 . The image acquisition mechanism 150 includes an electron beam column 102 (electron lens barrel) and an inspection room 103 . Inside the electron beam column 102 are an electron gun 201, an electromagnetic lens 202, a shaping aperture array substrate 203, a beam selection aperture substrate 232, a driving mechanism 234, an electromagnetic lens 205, a batch blanking deflector 212, a limiting aperture substrate 213, and an electromagnetic lens. 206, electromagnetic lens 207 (objective lens), main deflector 208, sub-deflector 209, E×B separator 214 (beam separator), deflector 218, electromagnetic lens 224, deflector 226, detector aperture array substrate 228, and a multi-detector 222 are arranged. Electron gun 201, electromagnetic lens 202, shaping aperture array substrate 203, electromagnetic lens 205, batch blanking deflector 212, limiting aperture substrate 213, beam selection aperture substrate 232, electromagnetic lens 206, electromagnetic lens 207 (objective lens), main deflection A primary electron optical system 151 (illumination optical system) is composed of the detector 208 and the sub-deflector 209 . Also, the electromagnetic lens 207, the E×B separator 214, the deflector 218, the electromagnetic lens 224, and the deflector 226 constitute a secondary electron optical system 152 (detection optical system).

A stage 105 movable at least in the XY directions is arranged in the examination room 103 . A substrate 101 (sample) to be inspected is placed on the stage 105 . 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. A chip pattern is composed of a plurality of graphic patterns. A plurality of chip patterns (wafer dies) are formed on the semiconductor substrate by exposing and transferring the chip patterns formed on the mask substrate for exposure a plurality of times onto the semiconductor substrate. The following mainly describes the case where the substrate 101 is a semiconductor substrate. The substrate 101 is placed on the stage 105, for example, with the pattern formation surface facing upward. A mirror 216 is arranged on the stage 105 to reflect the laser beam for laser length measurement emitted from the laser length measurement system 122 arranged outside the inspection room 103 . A mark 111 is arranged on the stage 105 so as to be adjusted to the same height position as the surface of the substrate 101 . A cross pattern, for example, is formed as the mark 111 .

The multi-detector 222 is also connected to the detection circuit 106 outside the electron beam column 102 . The detection circuit 106 is connected to the chip pattern memory 123 .

The multi-detector 222 has multiple detection elements arranged in an array. A plurality of openings are formed in the detector aperture array substrate 228 at the array pitch of the plurality of detection elements. A plurality of openings are formed circularly, for example. The center position of each opening is aligned with the center position of the corresponding detection element. Also, the size of the opening is formed smaller than the area size of the electron detection surface of the detection element. Detector aperture array substrate 228 may be integrally configured as part of the multi-detector 222 configuration.

In the control system circuit 160, a control computer 110 that controls the inspection apparatus 100 as a whole is connected via a bus 120 to a position circuit 107, a comparison circuit 108, a reference image generation circuit 112, a stage control circuit 114, a lens control circuit 124, a blanking Connected to a control circuit 126, a deflection control circuit 128, an E×B control circuit 133, a deflection adjustment circuit 134, a beam selection aperture control circuit 136, an image composition circuit 138, a storage device 109 such as a magnetic disk device, a memory 118, and a printer 119. It is The deflection control circuit 128 is also connected to DAC (digital-to-analog conversion) amplifiers 144 , 146 , 148 and 149 . The DAC amplifier 146 is connected to the main deflector 208 and the DAC amplifier 144 is connected to the sub deflector 209 . DAC amplifier 148 is connected to deflector 218 . DAC amplifier 149 is connected to deflector 226 .

Also, the chip pattern memory 123 is connected to the comparison circuit 108 and the image synthesizing circuit 132 . Also, the stage 105 is driven by a drive mechanism 142 under the control of the stage control circuit 114 . In the drive mechanism 142, for example, a drive system such as a three-axis (XY-.theta.) motor that drives in the X, Y and .theta. It's becoming These X motor, Y motor, and θ motor (not shown) can be step motors, for example. The stage 105 can be moved in horizontal and rotational directions by motors on the XY and .theta. axes. The movement position of the stage 105 is measured by the laser length measurement system 122 and supplied to the position circuit 107 . The laser length measurement system 122 measures the position of the stage 105 based on the principle of laser interferometry by receiving reflected light from the mirror 216 . For the stage coordinate system, for example, the X direction, Y direction, and θ direction of the primary coordinate system are set with respect to a plane perpendicular to the optical axis of the multi primary electron beam 20 .

The electromagnetic lens 202 , the electromagnetic lens 205 , the electromagnetic lens 206 , the electromagnetic lens 207 and the electromagnetic lens 224 are controlled by the lens control circuit 124 . E×B separator 214 is controlled by E×B control circuit 133 . The collective deflector 212 is an electrostatic deflector composed of two or more electrodes, and each electrode is controlled by the blanking control circuit 126 via a DAC amplifier (not shown). The sub-deflector 209 is an electrostatic deflector composed of four or more electrodes, and is controlled by the deflection control circuit 128 via the DAC amplifier 144 for each electrode. The main deflector 208 is an electrostatic deflector composed of four or more electrodes, and is controlled by the deflection control circuit 128 via the DAC amplifier 146 for each electrode. The deflector 218 is an electrostatic deflector composed of four or more electrodes, and is controlled by the deflection control circuit 128 via the DAC amplifier 148 for each electrode. The deflector 226 is an electrostatic deflector composed of four or more electrodes, and is controlled by the deflection control circuit 128 via the DAC amplifier 149 for each electrode.

Beam-selective aperture substrate 232 is driven by drive mechanism 234 , which is controlled by beam-selective aperture control circuit 136 .

A high-voltage power supply circuit (not shown) is connected to the electron gun 201, and an acceleration voltage is applied from the high-voltage power supply circuit between a filament (cathode) and an extraction electrode (anode) (not shown) in the electron gun 201, and another extraction electrode is applied. A group of electrons emitted from the cathode is accelerated by application of a (Wehnelt) voltage and heating of the cathode to a predetermined temperature, and is emitted as an electron beam 200 .

Here, FIG. 1 describes the configuration necessary for explaining the first embodiment. The inspection apparatus 100 may have other configurations that are normally required.

FIG. 2 is a conceptual diagram showing the configuration of the shaping aperture array substrate according to the first embodiment. In FIG. 2, the shaping aperture array substrate 203 has two-dimensional holes (openings) of horizontal (x direction) m ₁ rows x vertical (y direction) n ₁ stages (m ₁ and n ₁ are integers of 2 or more). ) 22 are formed at a predetermined arrangement pitch in the x and y directions. The example of FIG. 2 shows a case where 23×23 holes (openings) 22 are formed. Each hole 22 is formed in a rectangle having the same size and shape. Alternatively, they may be circular with the same outer diameter. Part of the electron beam 200 passes through each of the plurality of holes 22 to form the multiple primary electron beams 20 . Next, the operation of the image acquisition mechanism 150 when acquiring a secondary electron image will be described. The primary electron optical system 151 irradiates the substrate 101 with the multiple primary electron beams 20 . Specifically, it operates as follows.

An electron beam 200 emitted from an electron gun 201 (emission source) is refracted by an electromagnetic lens 202 to illuminate the entire shaped aperture array substrate 203 . A plurality of holes 22 (openings) are formed in the shaping aperture array substrate 203, as shown in FIG. The multiple primary electron beams 20 are formed by each part of the electron beam 200 irradiated to the positions of the plurality of holes 22 passing through the plurality of holes 22 of the shaped aperture array substrate 203 .

The formed multiple primary electron beams 20 are refracted by the electromagnetic lens 205 and the electromagnetic lens 206, respectively, and arranged on the intermediate image plane of each beam of the multiple primary electron beams 20 while repeating intermediate images and crossovers. It passes through E×B separator 214 to electromagnetic lens 207 (objective lens).

When the multiple primary electron beams 20 enter the electromagnetic lens 207 (objective lens), the electromagnetic lens 207 focuses the multiple primary electron beams 20 onto the substrate 101 . The multi-primary electron beams 20 focused (focused) on the substrate 101 (specimen) surface by the objective lens 207 are collectively deflected by the main deflector 208 and the sub-deflector 209, and the substrate 101 of each beam is deflected. Each irradiation position above is irradiated. When the entire multi-primary electron beam 20 is collectively deflected by the collective blanking deflector 212 , the position of the multi-primary electron beam 20 deviates from the center hole of the limiting aperture substrate 213 , and the multi-primary electron beam is deflected by the limiting aperture substrate 213 . The entire beam 20 is blocked. On the other hand, the multi-primary electron beams 20 not deflected by the collective blanking deflector 212 pass through the center hole of the limiting aperture substrate 213 as shown in FIG. Blanking control is performed by turning ON/OFF the batch blanking deflector 212, and ON/OFF of the beam is collectively controlled. Thus, the limiting aperture substrate 213 shields the multiple primary electron beams 20 that are deflected by the collective blanking deflector 212 to a beam-OFF state. The multiple primary electron beams 20 for image acquisition are formed by the group of beams that have passed through the limiting aperture substrate 213 and are formed from the time the beam is turned on until the beam is turned off.

When a desired position of the substrate 101 is irradiated with the multiple primary electron beams 20, each beam of the multiple primary electron beams 20 from the substrate 101 corresponds to the irradiation of the multiple primary electron beams 20. , a bundle of secondary electrons (multi secondary electron beam 300) including reflected electrons is emitted.

A multi-secondary electron beam 300 emitted from substrate 101 passes through electromagnetic lens 207 to E×B separator 214 . The E×B separator 214 has a plurality of magnetic poles of two or more poles using coils and a plurality of electrodes of two or more poles. For example, it has four magnetic poles (electromagnetic deflection coils) whose phases are shifted by 90° and four poles (electrostatic deflection electrodes) whose phases are similarly shifted by 90°. Then, for example, by setting two magnetic poles facing each other as an N pole and an S pole, a directional magnetic field is generated by the plurality of magnetic poles. Similarly, a directional electric field is generated by a plurality of such electrodes, for example, by applying potentials V of opposite signs to oppositely polarized electrodes. Specifically, the E×B separator 214 generates an electric field and a magnetic field in orthogonal directions on a plane orthogonal to the direction in which the central beam of the multi-primary electron beam 20 travels (orbit center axis). The electric field exerts a force in the same direction regardless of the electron's direction of travel. On the other hand, the magnetic field exerts a force according to Fleming's left-hand rule. Therefore, the direction of the force acting on the electrons can be changed depending on the electron penetration direction. In the multi-primary electron beam 20 entering the E×B separator 214 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, on the multi-secondary electron beam 300 entering the E×B 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 It is bent obliquely upward and separated from the trajectory of the multi primary electron beam 20 .

The multi-secondary electron beam 300 bent obliquely upward is further bent by the deflector 218 and projected onto the multi-detector 222 while being refracted by the electromagnetic lens 224 . Multi-detector 222 detects multiple secondary electron beams 300 projected through openings in detector aperture array substrate 228 . Each beam of the multi-primary electron beam 20 collides with a detection element corresponding to each secondary electron beam of the multi-secondary electron beam 300 on the detection surface of the multi-detector 222 to amplify the electrons and generate the secondary electron beams. Electronic image data is generated for each pixel. The intensity signal detected by the multi-detector 222 is output to the detection circuit 106 . Each primary electron beam is irradiated within a sub-irradiation area surrounded by the beam pitch in the x direction and the beam pitch in the y direction where the beam is positioned on the substrate 101, and scans the sub-irradiation area ( scanning).

FIG. 3 is a diagram showing an example of a plurality of chip regions formed on the semiconductor substrate according to the first embodiment. In FIG. 3, when the substrate 101 is a semiconductor substrate (wafer), a plurality of chips (wafer dies) 332 are formed in a two-dimensional array in an inspection area 330 of the semiconductor substrate (wafer). A mask pattern for one chip formed on a mask substrate for exposure is transferred to each chip 332 in a reduced size of, for example, 1/4 by an exposure device (stepper) (not shown). A mask pattern for one chip is generally composed of a plurality of figure patterns.

FIG. 4 is a diagram for explaining inspection processing according to the first embodiment. As shown in FIG. 4, the area of each chip 332 is divided into a plurality of stripe areas 32 with a predetermined width in the y direction, for example. The scanning operation by the image acquisition mechanism 150 is performed for each stripe region 32, for example. For example, while moving the stage 105 in the -x direction, the scanning operation of the stripe region 32 is relatively advanced in the x direction. Each stripe region 32 is divided into a plurality of rectangular regions 33 in the longitudinal direction. The movement of the beam to the target rectangular area 33 is performed by collective deflection of the entire multi-primary electron beam 20 by the main deflector 208 .

The example of FIG. 4 shows, for example, the case of a 5×5 array of multi-primary electron beams 20 . The irradiation area 34 that can be irradiated by one irradiation of the multi primary electron beams 20 is (the x direction obtained by multiplying the beam pitch in the x direction of the multi primary electron beams 20 on the surface of the substrate 101 by the number of beams in the x direction. size)×(the y-direction size obtained by multiplying the inter-beam pitch in the y-direction of the multi-primary electron beams 20 on the substrate 101 surface by the number of beams in the y-direction). The irradiation area 34 becomes the field of view of the multiple primary electron beams 20 . Each primary electron beam 8 constituting the multi-primary electron beam 20 is irradiated within a sub-irradiation region 29 surrounded by the beam-to-beam pitch in the x direction and the beam-to-beam pitch in the y direction where the beams are positioned. , scans (scanning operation) the inside of the sub-irradiation region 29 . Each primary electron beam 8 is in charge of one of sub-irradiation regions 29 different from each other. At each shot, each primary electron beam 8 irradiates the same position within the assigned sub-irradiation region 29 . Movement of the primary electron beam 8 within the sub-irradiation region 29 is performed by collective deflection of the entire multi-primary electron beam 20 by the sub-deflector 209 . Such an operation is repeated to sequentially irradiate one sub-irradiation region 29 with one primary electron beam 8 .

It is preferable to set the width of each stripe region 32 to the same size as the y-direction size of the irradiation region 34, or to a size narrower by the scan margin. The example of FIG. 4 shows the case where the irradiation area 34 has the same size as the rectangular area 33 . However, it is not limited to this. The irradiation area 34 may be smaller than the rectangular area 33 . Or it doesn't matter if it's big. Each primary electron beam 8 constituting the multi primary electron beam 20 is irradiated in the sub-irradiation region 29 where the beam is positioned, and the entire multi primary electron beam 20 is collectively deflected by the sub deflector 209. scans (scanning operation) the inside of the sub-irradiation region 29 by . When the scanning of one sub-irradiation region 29 is completed, the main deflector 208 collectively deflects the entire multi-primary electron beam 20 to move the irradiation position to the adjacent rectangular region 33 within the same stripe region 32 . Such an operation is repeated to sequentially irradiate the inside of the stripe region 32 . After the scanning of one stripe region 32 is completed, the irradiation region 34 moves to the next stripe region 32 by moving the stage 105 and/or collectively deflecting the entire multi-primary electron beam 20 by the main deflector 208 . As described above, each sub-irradiation area 29 is scanned and a secondary electron image is acquired by irradiation with each primary electron beam 8 . A secondary electron image of the rectangular area 33 , a secondary electron image of the striped area 32 , or a secondary electron image of the chip 332 is constructed by combining the secondary electron images of the respective sub-irradiation areas 29 . Also, when actually performing image comparison, the sub-irradiation area 29 in each rectangular area 33 is further divided into a plurality of frame areas 30, and the frame image 31 of each frame area 30 is compared. The example of FIG. 4 shows a case where a sub-irradiation area 29 scanned by one primary electron beam 8 is divided into four frame areas 30 formed by, for example, dividing each into two in the x and y directions. .

As described above, the image acquisition mechanism 150 advances the scanning operation for each stripe region 32 . As described above, the multi-primary electron beams 20 are irradiated, and the multi-secondary electron beams 300 emitted from the substrate 101 due to the irradiation of the multi-primary electron beams 20 are detected by the multi-detector 222. . The detected multiple secondary electron beam 300 may contain backscattered electrons. Alternatively, reflected electrons may be separated while moving through the secondary electron optical system 152 and may not reach the multi-detector 222 . Secondary electron detection data (measurement image data: secondary electron image data: inspection image data) for each pixel in each sub-irradiation region 29 detected by the multi-detector 222 is output to the detection circuit 106 in the order of measurement. be. In the detection circuit 106 , the analog detection data is converted into digital data by an A/D converter (not shown) and stored in the chip pattern memory 123 . The obtained measurement image data is transferred to the comparison circuit 108 together with information indicating each position from the position circuit 107 .

Here, since the multiple primary electron beams 20 scan the sub-irradiation region 29, the emission position of each secondary electron beam changes within the sub-irradiation region 29 every moment. Therefore, if nothing is done, each secondary electron beam will be projected at a position shifted from the corresponding detection element of the multi-detector 222 . Therefore, it is necessary for the deflector 226 to collectively deflect the multi-secondary electron beams 300 so that the secondary electron beams whose emission positions are changed in this way are irradiated in the corresponding detection areas of the multi-detector 222. . In order to irradiate each secondary electron beam into the corresponding detection area of the multi-detector 222, it is necessary to deflect (to offset) the positional movement of the multi-secondary electron beams caused by the change in emission position. . Therefore, it is required to match the deflection range (scanning range) of each primary electron beam of the multi-primary electron beam 20 with the deflection range (scanning range) of each secondary electron beam of the multi-secondary electron beam 300 .

FIG. 5 is a diagram showing an example of the internal configuration of the deflection adjustment circuit according to the first embodiment. In FIG. 5, the deflection adjustment circuit 134 includes storage devices 67 and 69 such as magnetic disk devices, a beam selection section 60, a primary system scanning condition setting section 61, a secondary system scanning condition setting section 62, a corner position setting section. 63, a determination unit 64, a determination unit 65, a composite image acquisition unit 66, a coordinate acquisition unit 70, and a deflection condition calculation unit 68 are arranged. A beam selection unit 60, a primary system scanning condition setting unit 61, a secondary system scanning condition setting unit 62, a corner position setting unit 63, a determination unit 64, a determination unit 65, a composite image acquisition unit 66, a coordinate acquisition unit 70, and deflection Each "section" such as the condition calculation section 68 includes a processing circuit, such as an electric circuit, computer, processor, circuit board, quantum circuit, semiconductor device, or the like. Also, each of the "-units" may use a common processing circuit (same processing circuit). Alternatively, different processing circuits (separate processing circuits) may be used. A beam selection unit 60, a primary system scanning condition setting unit 61, a secondary system scanning condition setting unit 62, a corner position setting unit 63, a determination unit 64, a determination unit 65, a composite image acquisition unit 66, a coordinate acquisition unit 70, and deflection Necessary input data or calculated results in the condition calculation unit 68 are stored in a memory (not shown) or the memory 118 each time.

FIG. 6 is a flow chart showing an example of main steps of the inspection method according to the first embodiment. 6, the main steps of the inspection method in the first embodiment are a beam selection step (S102), a scanning condition setting step (S104), a primary beam position setting step (S106), and a primary beam irradiation step. (S108), a secondary beam scanning step (S110), a secondary beam detection (image acquisition) step (S112), a determination step (S114), a determination step (S116), and an image synthesizing step (S120) , a coordinate acquisition step (S121), a secondary beam deflection condition calculation step (S122), a secondary beam deflection condition setting step (S124), an inspection image acquisition step (S130), and a reference image creation step (S132). and a comparison step (S140).

As the beam selection step ( S<b>102 ), the beam selector 60 selects the representative primary electron beam 10 from the multiple primary electron beams 200 . For example, the central beam of the multiple primary electron beams 200 is selected as the representative primary electron beam 10 . The representative primary electron beam 10 is not limited to one. You may select two or more. When two or more are selected, they are sequentially irradiated one by one.

FIG. 7 is a diagram for explaining how beams are selected according to the first embodiment. In FIG. 7, the small aperture 13 is formed to have a size through which one primary electron beam can pass. The large aperture 11 is formed in a size that allows the entire multi primary electron beam 20 to pass through. Under the control of the beam selective aperture control circuit 136, the drive mechanism 234 horizontally moves the beam selective aperture substrate 232 to create a small aperture on the trajectory of one primary electron beam of the multi primary electron beams 20. The alignment of 13 selectively allows such a single primary electron beam to pass through. The remaining beams are blocked by the beam selection aperture substrate 232 .

As the scanning condition setting step ( S<b>104 ), the primary system scanning condition setting unit 61 sets scanning conditions for the multi primary electron beam 20 . Scanning widths in the x and y directions are set as scanning conditions for the multi-primary electron beam 20 . Here, the width of the sub irradiation area 29 in the x and y directions is set. Alternatively, it may be a width with a margin added. In addition, a relative angle with the mark 111 may be set.

Further, the secondary system scanning condition setting unit 62 sets temporary scanning conditions for the multi-secondary electron beam 300 . As temporary scanning conditions for the multi-secondary electron beam 300, scanning widths in the x and y directions are set.

In order to match the deflection range (scanning range) of each primary electron beam of the multi-primary electron beam 20 with the deflection range (scanning range) of each secondary electron beam of the multi-secondary electron beam 300, The four corner positions (four corner positions) of the scanning range and the corresponding four corner positions (four corner positions) of the scanning range of the secondary electron beam may be matched.

As the primary beam position setting step (S106), the corner position setting unit 63 sets one of the four corner positions of the scanning range of the primary electron beam. For example, the lower left corner position of the scanning range of the primary electron beam is set.

As the primary beam irradiation step (S108), the image acquisition mechanism 150 irradiates the stage 105 with a representative primary electron beam. At that time, the main deflector 208 aligns the center of the multi-primary electron beam with the trajectory central axis of the multi-primary electron beam. Even if it is not deflected, if it is positioned on the trajectory center axis of the multiple primary electron beams, it may be without deflection. As a result, each primary electron beam is irradiated to the scanning center position of the scanning range of the respective primary electron beam. Here, beams other than the representative primary electron beam are shielded by the beam selection aperture substrate 232 , so only the representative primary electron beam reaches the stage 105 . Here, an evaluation substrate is arranged at the irradiation position on the stage 105 . Alternatively, marks 111 may be placed. Alternatively, it may be the upper surface of the stage 105 .

FIG. 8 is a diagram for explaining the position of the representative secondary electron beam when the representative primary electron beam is applied to the scanning center of the scanning range of the primary electron beam in the first embodiment. In FIG. 8A, when the representative primary electron beam 21 is irradiated to the scanning center of the scanning range, a representative secondary electron beam 301 corresponding to the representative primary electron beam 21 is emitted from the stage 105 . A representative secondary electron beam 301 is projected onto the multi-detector 222 via the detector aperture array substrate 228 by the secondary electron optical system 152 . In this state, the representative secondary electron beam 301 is scanned within the currently set secondary beam scanning range by the deflector 226 . Thereby, an aperture image of the detector aperture array substrate 228 is captured by the corresponding detection element. If the representative primary electron beam 21 is the center beam of the multiple primary electron beams 20 , the corresponding element will be the center detection element of the multiple detector 222 . When the representative primary electron beam 21 is irradiated to the scanning center of the scanning range of the primary electron beam, as shown in FIG. coincides with the center of the detection area. Therefore, as shown in FIG. 8(c), the aperture image captured by the detection element is positioned at the center of the image.

Next, the sub deflector 209 (primary system deflector) shifts the representative primary electron beam 21 to a plurality of positions within a preset primary beam deflection range (scanning range) on the stage 105 at different times. Irradiate in order. Here, the representative primary electron beam is deflected so as to irradiate the lower left corner position of the set scanning range of the primary electron beam.

FIG. 9 is a diagram for explaining an example of the position of the representative secondary electron beam 301 when the representative primary electron beam 21 is applied to the lower left corner position of the scanning range of the primary electron beam in the first embodiment. . As shown in FIG. 9A, beam deflection by the sub-deflector 209 causes the representative primary electron beam 21 to irradiate the lower left corner position of the scanning range.

In the secondary beam scanning step (S110), the deflector 226 (secondary system deflector) causes the representative primary electron beam 21 to irradiate the representative primary electron beam 21 for each of a plurality of positions in the representative primary beam deflection range. A representative secondary electron beam 301 emitted from a position is scanned under a temporary secondary beam deflection condition. Here, as described above, four corner positions are used as a plurality of positions of the representative primary beam deflection range. Here, the representative secondary electron beam 301 is scanned by the deflector 226 for the lower left corner position of the representative primary beam deflection range. The provisional secondary beam deflection condition is the provisional scanning condition of the multi-secondary electron beam 300 currently set.

In FIG. 9A, when the representative primary electron beam 21 irradiates the lower left corner position of the scanning range, a representative secondary electron beam 301 corresponding to the representative primary electron beam 21 is emitted from the stage 105 . A representative secondary electron beam 301 is projected onto the multi-detector 222 via the detector aperture array substrate 228 by the secondary electron optical system 152 . Since the representative primary electron beam 21 does not irradiate the scan center, the scan center position of the representative secondary electron beam 301 deviates from the detection area center of the corresponding detection element. FIG. 9B shows a case where the scan center position of the representative secondary electron beam 301 is shifted, for example, to the upper left side with respect to the center of the detection area of the detection element. In this state, the representative secondary electron beam 301 is scanned within the currently set secondary beam scanning range by the deflector 226 .

In the secondary beam detection (image acquisition) step (S112), the corresponding detection elements (predetermined detection elements) of the multi-detector 222 detect temporary secondary beams for each of a plurality of positions in the representative primary beam deflection range. A representative secondary electron beam 301 scanned under beam deflection conditions is detected. Here, the scanned representative secondary electron beam 301 is detected for the lower left corner position of the representative primary beam deflection range. When the representative primary beam 21 is applied to the lower left corner position of the scanning range, the generated representative secondary beam reaches the upper left of the corresponding detection element. Then, the representative secondary electron beam 301 reaches the detection element only when it passes over the opening of the detector aperture array substrate 228 by the scanning operation, and is detected by this detection element. Thereby, an aperture image of the detector aperture array substrate 228 is captured by the corresponding detection element. Since the detection area is located on the lower right side with respect to the scan center of the representative secondary electron beam 301, as shown in FIG. will be located on the side. A rectangular frame of the detected image indicates the secondary beam scanning range. A detected image of the representative secondary electron beam 301 is output to the image synthesizing circuit 138 .

As a determination step (S114), the determination unit 64 determines whether an aperture image (secondary beam image) has been obtained. If the aperture image cannot be obtained, the process returns to the scanning condition setting step (S104), and the scanning conditions are changed and set again. For example, the scan range of the secondary beam may be too narrow so that the secondary electron beam does not cross the aperture of the detector aperture array substrate 228 . In that case, the scan width should be expanded. Then, the scanning condition setting step (S104) to the determination step (S114) are repeated until an aperture image is obtained. When the aperture image is obtained, the process proceeds to the determination step (S116).

As the determination step (S116), the determination unit 65 determines whether or not the imaging of aperture images at all corner positions has been completed. When the processing ends at all corner positions, the process proceeds to the image synthesizing step (S120). If not completed at all corner positions, return to the primary beam position setting step (S106), and repeat the primary beam position setting step (S106) to determination step (S116) until all corner positions are completed. .

FIG. 10 is a diagram for explaining an example of the position of the representative secondary electron beam 301 when the representative primary electron beam is applied to the lower right corner position of the scanning range of the primary electron beam in the first embodiment. . As shown in FIG. 10(a), the beam deflection by the sub-deflector 209 causes the representative primary electron beam to irradiate the lower right corner position of the scanning range.

In FIG. 10A, when the representative primary electron beam 21 irradiates the lower right corner position of the scanning range, a representative secondary electron beam 301 corresponding to the representative primary electron beam 21 is emitted from the stage 105. . A representative secondary electron beam 301 is projected onto the multi-detector 222 via the detector aperture array substrate 228 by the secondary electron optical system 152 . Since the representative primary electron beam 21 does not irradiate the scan center, the scan center position of the representative secondary electron beam 301 deviates from the detection area center of the corresponding detection element. FIG. 10B shows a case where the scan center position of the representative secondary electron beam 301 is shifted, for example, to the upper right side with respect to the center of the detection area of the detection element. In this state, the representative secondary electron beam 301 is scanned within the currently set secondary beam scanning range by the deflector 226 .

When the representative primary beam 21 is applied to the lower right corner position of the scanning range, the generated representative secondary beam reaches the upper right of the corresponding detection element. Then, the representative secondary electron beam 301 reaches the detection element only when it passes over the opening of the detector aperture array substrate 228 by the scanning operation, and is detected by this detection element. Thereby, an aperture image of the detector aperture array substrate 228 is captured by the corresponding detection element. Since the detection area is located on the lower left side with respect to the scan center of the representative secondary electron beam 301, as shown in FIG. will be located. A rectangular frame of the detected image indicates the secondary beam scanning range. A detected image of the representative secondary electron beam 301 is output to the image synthesizing circuit 138 .

FIG. 11 is a diagram for explaining an example of the position of the representative secondary electron beam 301 when the upper right corner position of the scanning range of the primary electron beam is irradiated with the representative primary electron beam 21 in the first embodiment. . As shown in FIG. 11A, beam deflection by the sub-deflector 209 irradiates the representative primary electron beam 21 onto the upper right corner position of the scanning range.

In FIG. 11A, when the representative primary electron beam 21 irradiates the upper right corner position of the scanning range, a representative secondary electron beam 301 corresponding to the representative primary electron beam 21 is emitted from the stage 105 . A representative secondary electron beam 301 is projected onto the multi-detector 222 via the detector aperture array substrate 228 by the secondary electron optical system 152 . Since the representative primary electron beam 21 does not irradiate the scan center, the scan center position of the representative secondary electron beam 301 deviates from the detection area center of the corresponding detection element. FIG. 11(b) shows a case where the scan center position of the representative secondary electron beam 301 is shifted, for example, to the lower right side with respect to the center of the detection area of the detection element. In this state, the representative secondary electron beam 301 is scanned within the currently set secondary beam scanning range by the deflector 226 .

When the representative primary beam 21 is irradiated to the upper right corner position of the scanning range, the generated representative secondary beam reaches the lower right of the corresponding detection element. Then, the representative secondary electron beam 301 reaches the detection element only when it passes over the opening of the detector aperture array substrate 228 by the scanning operation, and is detected by this detection element. Thereby, an aperture image of the detector aperture array substrate 228 is captured by the corresponding detection element. Since the detection area is located on the upper left side with respect to the scan center of the representative secondary electron beam 301, the aperture image picked up by the detection element is located on the upper left side from the center of the image, as shown in FIG. 11(c). will be located. A rectangular frame of the detected image indicates the secondary beam scanning range. A detected image of the representative secondary electron beam 301 is output to the image synthesizing circuit 138 .

FIG. 12 is a diagram for explaining an example of the position of the representative secondary electron beam 301 when the upper left corner position of the scanning range of the primary electron beam is irradiated with the representative primary electron beam 21 in the first embodiment. . As shown in FIG. 12A, beam deflection by the sub-deflector 209 causes the representative primary electron beam 21 to irradiate the upper left corner position of the scanning range.

In FIG. 12A, when the representative primary electron beam 21 irradiates the upper left corner position of the scanning range, a representative secondary electron beam 301 corresponding to the representative primary electron beam 21 is emitted from the stage 105 . A representative secondary electron beam 301 is projected onto the multi-detector 222 via the detector aperture array substrate 228 by the secondary electron optical system 152 . Since the representative primary electron beam 21 does not irradiate the scan center, the scan center position of the representative secondary electron beam 301 deviates from the detection area center of the corresponding detection element. FIG. 12(b) shows a case where the scan center position of the representative secondary electron beam 301 is shifted, for example, to the lower left side with respect to the center of the detection area of the detection element. In this state, the representative secondary electron beam 301 is scanned within the currently set secondary beam scanning range by the deflector 226 .

When the representative primary beam 21 is applied to the upper left corner position of the scanning range, the generated representative secondary beam reaches the lower left corner of the corresponding detection element. Then, the representative secondary electron beam 301 reaches the detection element only when it passes over the opening of the detector aperture array substrate 228 by the scanning operation, and is detected by this detection element. Thereby, an aperture image of the detector aperture array substrate 228 is captured by the corresponding detection element. Since the detection area is located on the upper right side with respect to the scan center of the representative secondary electron beam 301, as shown in FIG. will be located. A rectangular frame of the detected image indicates the secondary beam scanning range. A detected image of the representative secondary electron beam 301 is output to the image synthesizing circuit 138 .

In the image synthesizing step (S120), the image synthesizing circuit 138 synthesizes detected images of the representative secondary electron beams 301 detected for each of a plurality of positions within the primary beam deflection range.

13 is a diagram showing an example of a composite image according to Embodiment 1. FIG. FIG. 13(a) shows an example of a synthesized image obtained by synthesizing aperture images captured at four corner positions. As shown in FIG. 13B, the rectangular frame of the synthesized image indicates the secondary beam scanning range. A rectangular frame formed by connecting the centers of the four aperture images indicates the primary beam scanning range. For example, if the scanning direction of the primary electron beam is from the left side to the right side of the scanning range of the primary beam, the scanning direction of the secondary electron beam will be in the opposite direction to offset the scanning of the primary electron beam. . In the example of FIG. 13B, it can be seen from the synthesized image that there is a magnification shift between the primary beam scanning range and the secondary beam scanning range. Also, it can be seen that there is a rotational deviation between the primary beam scanning range and the secondary beam scanning range.

The composite image acquisition unit 66 acquires the composite image created by the image composition circuit 138 and temporarily stores it in the storage device 67 .

In the coordinate acquisition step (S121), the coordinate acquisition unit 70 acquires a plurality of coordinates corresponding to a plurality of positions based on the detected image of the representative secondary electron beam detected for each of the plurality of positions in the primary beam deflection range. to get Specifically, the coordinate acquisition unit 70 acquires a plurality of coordinates corresponding to a plurality of positions using the synthesized composite image. For example, a vector from the image center of the detected image, which is the scanning center of the secondary electron beam, to each aperture image is calculated. The position of the image center of the detection image is the position of the corresponding detection element. The position of each detection element of multi-detector 222 is known in advance. Therefore, each coordinate can be obtained by adding the relative position from the position of the corresponding detection element to the position of the corresponding detection element. Alternatively, the coordinates may be calculated by obtaining the number of pixels from the upper left of the position corresponding to each beam center coordinate when the upper left of the image is assumed to be the coordinates (0, 0).

In the secondary beam deflection condition calculation step (S122), the deflection condition calculation unit 68 uses the acquired plurality of coordinates to calculate the representative second beam caused by the movement of the representative primary electron beam 21 within the primary beam scanning range. Secondary beam deflection conditions are calculated so that the movement of the secondary electron beam 301 is canceled and the irradiation position of the representative secondary electron beam 301 on the corresponding detection element is fixed. A plurality of coordinates are obtained from the combined composite image.

Here, the plurality of coordinates corresponding to the plurality of positions are not limited to being obtained from the composite image. For example, if the beam positions in the detection images of the four positions before synthesis are calculated with coordinates based on the same origin (for example, the upper left of the image), relative coordinates between the four beams can be obtained by comparison.

The deflection condition calculator 68 calculates each parameter of the deflection condition. It has a deflection magnification and a deflection rotation angle as parameters of the deflection condition of the secondary electron beam. Specifically, it operates as follows.

FIG. 14 is a diagram showing an example of the relative relationship between the primary beam scanning range and the secondary beam scanning range according to the first embodiment. The deflection condition calculator 68 calculates the x-direction deflection magnification Mag(sx) of the secondary beam scanning range, the y-direction deflection magnification Mag(sy) of the secondary beam scanning range, the primary beam scanning range and the secondary beam A deflection rotation angle θ with respect to the scanning range is calculated. In the example of FIG. 14, the x-direction deflection magnification Mag(sx) of the secondary beam scanning range is the value obtained by dividing the x-direction width Sx of the secondary beam scanning range by the x-direction width Px of the primary beam scanning range. defined by The y-direction deflection magnification Mag(sy) of the secondary beam scanning range is defined as a value obtained by dividing the y-direction width Sy of the secondary beam scanning range by the y-direction width Py of the primary beam scanning range. More preferably, the deflection condition calculator 68 further calculates an x-direction skew (φx) and a y-direction skew (φy) of the primary beam scanning range with respect to the secondary beam scanning range. Skew (φx) indicates the amount of skew in which the rectangle is tilted in the x direction. Skew (φy) indicates the amount of skew in which the rectangle is tilted in the y direction. FIG. 14 shows a case where Skew(φx)=0 and Skew(φy)=0.

As the secondary beam deflection condition setting step (S124), the deflection control circuit 128 sets the calculated deflection condition of the secondary electron beam. In other words, the deflection condition of the deflector 226 is set. Specifically, it is set to a value obtained by dividing the temporary scan width in the x direction by the deflection magnification Mag(sx). A value obtained by dividing the temporary scan width in the y direction by the deflection magnification Mag(sy) is set. Also, the deflection range is rotated by the deflection rotation angle θ. If Skew(φx) and Skew(φy) are finite values, the deflection is made so that Skew(φx) and Skew(φy) become zero.

15 is a diagram showing an example of a synthesized image after adjustment according to Embodiment 1. FIG. When the primary beam scanning range and the secondary beam scanning range match, the centers of the four aperture images are positioned at the four corners in the composite image as shown in FIG. By setting the calculated deflection condition of the secondary electron beam, the primary beam scanning range and the secondary beam scanning range can be matched as shown in FIG.

In the inspection image acquisition step (S130), the image acquisition mechanism 150 irradiates the substrate with the multiple primary electron beams 20, and acquires a secondary electron image of the substrate 101 from the multiple secondary electron beams 300 emitted from the substrate. do. In other words, the sub-deflector 208 scans the substrate 101 mounted on the stage 105 using the multiple primary electron beams 20 within the primary electron beam scanning range. Then, the multi-secondary electron beams are detected by the multi-detector 222 while scanning the multi-secondary electron beams 300 emitted from the substrate 101 by beam deflection by the deflector 226 in accordance with the calculated secondary beam deflection conditions. . A secondary electron image of the substrate 101 is thus obtained.

Then, the image acquisition mechanism 150 advances the scanning operation for each stripe region 32 as described above. The detected multiple secondary electron beam 300 may contain backscattered electrons. Alternatively, reflected electrons may be separated while moving through the secondary electron optical system 152 and may not reach the multi-detector 222 . Secondary electron detection data (measurement image data: secondary electron image data: inspection image data) for each pixel in each sub-irradiation region 29 detected by the multi-detector 222 is output to the detection circuit 106 in the order of measurement. be. In the detection circuit 106 , the analog detection data is converted into digital data by an A/D converter (not shown) and stored in the chip pattern memory 123 . The obtained measurement image data is transferred to the comparison circuit 108 together with information indicating each position from the position circuit 107 .

As the image acquisition operation described above, a step-and-repeat operation may be performed in which the substrate 101 is irradiated with the multi-primary electron beam 20 while the stage 105 is stopped, and the position is moved after the scanning operation is completed. Alternatively, the substrate 101 may be irradiated with the multiple primary electron beams 20 while the stage 105 is continuously moving. When the substrate 101 is irradiated with the multi-primary electron beams 20 while the stage 105 is continuously moving, a tracking operation is performed by the main deflector 208 so that the irradiation position of the multi-primary electron beams 20 follows the movement of the stage 105. is done. Therefore, the emission positions of the multi-secondary electron beams 300 change every second with respect to the orbital central axis of the multi-primary electron beams 20 . The deflector 226 preferably collectively deflects the multi-secondary electron beams 300 so that the secondary electron beams whose emission positions have been changed by such a tracking operation are applied to the corresponding detection regions of the multi-detector 222 .

FIG. 16 is a configuration diagram showing an example of the internal configuration of the comparison circuit according to the first embodiment. 16, storage devices 50, 52, 56 such as magnetic disk devices, a frame image forming section 54, an alignment section 57, and a comparison section 58 are arranged in the comparison circuit 108. FIG. Each of the frame image generator 54, alignment unit 57, and comparison unit 58 includes a processing circuit, which may be an electric circuit, computer, processor, circuit board, quantum circuit, or semiconductor. equipment, etc. are included. Also, each of the "-units" may use a common processing circuit (same processing circuit). Alternatively, different processing circuits (separate processing circuits) may be used. Necessary input data or calculation results in the frame image creating section 54, the positioning section 57, and the comparing section 58 are stored in a memory (not shown) or the memory 118 each time.

The measured image data (beam image) transferred into the comparison circuit 108 is stored in the storage device 50 .

Then, the frame image creating unit 54 creates a frame image 31 for each of a plurality of frame areas 30 obtained by further dividing the image data of the sub-irradiation areas 29 acquired by the scanning operation of each primary electron beam 8. . Then, the frame area 30 is used as a unit area of the image to be inspected. It should be noted that each frame area 30 is preferably configured such that the margin areas overlap each other so that there is no missing image. The created frame image 31 is stored in the storage device 56 .

In the reference image creation step (S132), the reference image creation circuit 112 creates a reference image corresponding to the frame image 31 for each frame region 30 based on the design data that is the basis of the plurality of graphic patterns formed on the substrate 101. to create Specifically, it operates as follows. First, the design pattern data is read from the storage device 109 through the control computer 110, and each graphic pattern defined in the read design pattern data is converted into binary or multi-value image data.

As described above, the figures defined in the design pattern data are, for example, rectangles and triangles as basic figures. The figure data defining the shape, size, position, etc. of each pattern figure is stored with information such as figure code, which is an identifier for distinguishing figure types.

When the design pattern data as such graphic data is input to the reference image generating circuit 112, it is developed into data for each graphic, and the graphic code, graphic dimensions, etc. indicating the graphic shape of the graphic data are interpreted. Then, it develops into binary or multi-valued design pattern image data as a pattern to be arranged in a grid of a predetermined quantization size as a unit, and outputs the data. In other words, the design data is read, and the occupancy rate of the figure in the design pattern is calculated for each square obtained by virtually dividing the inspection area into squares having a predetermined size as a unit, and n-bit occupancy rate data is obtained. Output. For example, it is preferable to set one square as one pixel. Assuming that one pixel has a resolution of 1/2 ⁸ (=1/256), a small area of 1/256 is allocated for the area of the figure arranged in the pixel, and the occupancy rate in the pixel is reduced. Calculate. Then, it becomes 8-bit occupancy rate data. Such squares (inspection pixels) may be aligned with the pixels of the measurement data.

Next, the reference image generation circuit 112 filters the design image data of the design pattern, which is image data of the figure, using a predetermined filter function. As a result, the design image data, which is image data on the design side in which the image intensity (gradation value) is a digital value, can be matched with the image generation characteristics obtained by the irradiation of the multi-primary electron beams 20 . Image data for each pixel of the created reference image is output to the comparison circuit 108 . The reference image data transferred into the comparison circuit 108 is stored in the storage device 52 .

As the comparison step (S140), first, the alignment unit 57 reads out the frame image 31 to be the image to be inspected and the reference image corresponding to the frame image 31, and aligns both images in units of sub-pixels smaller than pixels. Align. For example, alignment may be performed using the method of least squares.

Then, the comparison unit 58 compares at least part of the obtained secondary electron image with a predetermined image. Here, frame images obtained by further dividing the image of the sub-irradiation region 29 acquired for each beam are used. Therefore, the comparison unit 58 compares the frame image 31 and the reference image pixel by pixel. A comparison unit 58 compares the two for each pixel according to a predetermined determination condition, and determines whether or not there is a defect such as a shape defect. For example, if the gradation value difference for each pixel is larger than the determination threshold value Th, it is determined as defective. Then, the comparison result is output. The comparison result may be output to the storage device 109 or memory 118, or output from the printer 119. FIG.

In the above example, the die-database inspection has been described, but the present invention is not limited to this. It may be a case where a die-to-die inspection is performed. When performing a die-to-die inspection, between a target frame image 31 (die 1) and a frame image 31 (die 2) in which the same pattern as the frame image 31 is formed (another example of a reference image) , the alignment and comparison processing described above may be performed.

As described above, according to Embodiment 1, the positions of the multi-secondary electron beams accompanying the scanning of the multi-primary electron beams can be detected without using a measuring means other than the multi-detector 222 for capturing an image. An image can be acquired with deflection adjustment of multiple secondary electron beams to compensate for movement.

Embodiment 2.
In Embodiment 1, the configuration in which the remaining beam array is shielded by the beam selection aperture substrate 232 in order to select the representative primary electron beam 21 from the multiple primary electron beams 20 has been described. In Embodiment 2, a configuration will be described in which a part of the multi primary electron beam 20 is not shielded and the entire beam is irradiated. The configuration of the inspection apparatus 100 according to Embodiment 2 may be the same as that shown in FIG. However, the beam selection aperture substrate 232, the drive mechanism 234, and the beam selection aperture control circuit 136 may be omitted. Principal steps of the inspection method in the second embodiment may be the same as those shown in FIG. In addition, the contents other than those to be particularly described may be the same as those in the first embodiment.

FIG. 17 is a diagram for explaining representative primary electron beams in the second embodiment. The example of FIG. 17 shows a case where 4×4 multi-primary electron beams 20 are used. The reason for limiting the beams to be irradiated in the first embodiment is to identify which beam is the target beam in the obtained image. However, when the entire multi-primary electron beam 20 is irradiated, it is difficult to identify which beam is the target beam in the image obtained in the central region of the beam array. On the other hand, as shown in FIG. 17, the four corner beams A11, A14, A41 and A44 at the four corners of the multi-primary electron beam 20 can be identified from their arrangement relationship. Therefore, in the second embodiment, at least one of the four corner beams is used to obtain the deflection condition of the secondary electron beam.

As the beam selection step ( S<b>102 ), the beam selection unit 60 selects a representative primary electron beam from the multiple primary electron beams 200 . Here, one is selected from four corner beams A11, A14, A41 and A44 shown in FIG. Here, for example, the corner beam A14 is selected. However, in Embodiment 2, the remaining beams of the multi primary electron beam 20 need not be shielded.

The contents of the scanning condition setting step (S104) are the same as in the first embodiment.

As the primary beam position setting step (S106), the corner position setting unit 63 sets one of the four corner positions of the scanning range of the primary electron beam. For example, the lower left corner position of the scanning range of the primary electron beam is set.

As the primary beam irradiation step (S108), the image acquisition mechanism 150 irradiates the stage 105 with the multiple primary electron beams 20 including the representative primary electron beam. At that time, the main deflector 208 aligns the center of the multi-primary electron beam with the trajectory central axis of the multi-primary electron beam. Even if it is not deflected, if it is positioned on the trajectory center axis of the multiple primary electron beams, it may be without deflection.

Next, the sub deflector 209 (primary system deflector) sequentially shifts the representative primary electron beam to a plurality of positions within a primary beam deflection range (scanning range) set in advance on the stage 105 at different times. Irradiate. Here, the representative primary electron beam is deflected so as to irradiate the lower left corner position of the set scanning range of the primary electron beam. Due to such deflection, the remaining beam array of the multiple primary electron beams 20 also irradiates the lower left corner position of the scanning range of each primary electron beam.

FIG. 18 is a diagram for explaining an example of the position of the representative secondary electron beam when the lower left corner position of the scanning range of the primary electron beam is irradiated with the representative primary electron beam in the second embodiment. As shown in FIG. 18A, beam deflection by the sub-deflector 209 irradiates the representative primary electron beam A14 onto the lower left corner position of the scanning range.

In the secondary beam scanning step (S110), the deflector 226 (secondary system deflector) scans a plurality of positions in the representative primary beam deflection range for each position due to the irradiation of the representative primary electron beam. A representative secondary electron beam emitted from is scanned under a temporary secondary beam deflection condition. Here, as described above, four corner positions are used as a plurality of positions of the representative primary beam deflection range. Here, the multiple primary electron beams 20 including the representative secondary electron beam A14 are scanned at the lower left corner position of the representative primary beam deflection range by collective deflection by the deflector 226 .

In FIG. 18A, when the representative primary electron beam is applied to the lower left corner position of the scanning range, a representative secondary electron beam B14 corresponding to the representative primary electron beam is emitted from the stage 105. FIG. At the same time, secondary electron beams corresponding to each of the other primary electron beams are emitted from stage 105 . These multiple secondary electron beams 300 are projected onto the multiple detector 222 via the detector aperture array substrate 228 by the secondary electron optical system 152 . Since the representative primary electron beam A14 does not irradiate the scan center, the scan center position of the representative secondary electron beam B14 deviates from the center of the detection area of the corresponding detection element D14. FIG. 18B shows a case where the scan center position of the representative secondary electron beam B14 is shifted, for example, to the upper left side with respect to the center of the detection area of the detection element. In this state, the deflector 226 scans the currently set secondary beam scanning range for the multiple secondary electron beams 300 including the representative secondary electron beam.

In the secondary beam detection (image acquisition) step (S112), the corresponding detection element D14 of the multi-detector 222 detects a temporary secondary beam deflection condition for each of a plurality of positions in the deflection range of the representative primary beam A14. A representative secondary electron beam B14 scanned by is detected. Here, the scanned representative secondary electron beam B14 is detected for the lower left corner position of the representative primary beam deflection range. Representative secondary electron beam B14 reaches detector element D14 and is detected by detector element D14 only when it passes over the opening of detector aperture array substrate 228 due to the scanning motion.

Here, in the second embodiment, the detection element D14 is arranged so that two or more secondary electron beams are detected in each of the x and y directions so that the representative secondary electron beam B14 can be identified as a corner beam. , the secondary beam scanning range is set in advance. Therefore, the range is set within a range where scanning of two beam pitches is possible in the x and y directions from the scanning center of the secondary electron beam. The example of FIG. 18(b) shows the case where the scanning width in the x and y directions of the secondary beam scanning range is set to a value four times the beam pitch. As a result, the corresponding detector element D14 captures an aperture image of the detector aperture array substrate 228 for a plurality of beams. Since the detection area is located on the lower right side with respect to the scan center of the representative secondary electron beam B14, as shown in FIG. The aperture image will be located on the lower right side from the center of the image. Aperture images of the remaining detected secondary electron beams B13, B24, B23, B34, B33, B44 and B43 are arranged at respective positions along the arrangement of the beam array. Since the representative secondary electron beam B14 is a corner beam, even if the aperture images of a plurality of secondary electron beams appear together, the corner aperture image can be identified as the aperture image of the representative secondary electron beam B14. A rectangular frame of the detected image indicates the secondary beam scanning range. A detected image of the representative secondary electron beam B14 is output to the image synthesizing circuit 138 .

The contents of the determination step (S114) and the determination step (S116) are the same as in the first embodiment.

FIG. 19 is a diagram for explaining an example of the position of the representative secondary electron beam when the lower right corner position of the scanning range of the primary electron beam is irradiated with the representative primary electron beam in the second embodiment. As shown in FIG. 19A, beam deflection by the sub-deflector 209 irradiates the representative primary electron beam A14 onto the lower right corner position of the scanning range.

In FIG. 19A, when the representative primary electron beam A14 irradiates the lower right corner position of the scanning range, a representative secondary electron beam B14 corresponding to the representative primary electron beam A14 is emitted from the stage 105. . At the same time, secondary electron beams corresponding to each of the other primary electron beams are emitted from stage 105 . These multiple secondary electron beams 300 are projected onto the multiple detector 222 via the detector aperture array substrate 228 by the secondary electron optical system 152 . Since the representative primary electron beam A14 does not irradiate the scan center, the scan center position of the representative secondary electron beam B14 deviates from the center of the detection area of the corresponding detection element D14. FIG. 19B shows a case where the scan center position of the representative secondary electron beam B14 is shifted, for example, to the upper right side with respect to the center of the detection area of the detection element D14. In this state, the deflector 226 scans the currently set secondary beam scanning range for the multiple secondary electron beams 300 including the representative secondary electron beam.

As the secondary beam detection (image acquisition) step (S112), here, the scanned representative secondary electron beam B14 is detected for the lower right corner position of the representative primary beam deflection range. The example of FIG. 19(b) shows the case where the scanning width in the x and y directions of the secondary beam scanning range is set to a value four times the beam pitch. As a result, the corresponding detector element D14 captures an aperture image of the detector aperture array substrate 228 for a plurality of beams. Since the detection area is located on the lower left side with respect to the scan center of the representative secondary electron beam B14, as shown in FIG. The image will be located on the lower left side from the center of the image. Aperture images of the remaining detected secondary electron beams B11-B13, B21-B24, B31-B34, and B41-B44 are arranged at respective positions along the arrangement of the beam array. Since the representative secondary electron beam B14 is a corner beam, even if the aperture images of a plurality of secondary electron beams appear together, the corner aperture image can be identified as the aperture image of the representative secondary electron beam B14. A rectangular frame of the detected image indicates the secondary beam scanning range. A detected image of the representative secondary electron beam B14 is output to the image synthesizing circuit 138 .

FIG. 20 is a diagram for explaining an example of the position of the representative secondary electron beam when the upper left corner position of the scanning range of the primary electron beam is irradiated with the representative primary electron beam in the second embodiment. As shown in FIG. 20A, beam deflection by the sub-deflector 209 causes the representative primary electron beam A14 to irradiate the upper left corner position of the scanning range.

In FIG. 20A, when the representative primary electron beam A14 irradiates the upper left corner position of the scanning range, a representative secondary electron beam B14 corresponding to the representative primary electron beam A14 is emitted from the stage 105. FIG. At the same time, secondary electron beams corresponding to each of the other primary electron beams are emitted from stage 105 . These multiple secondary electron beams 300 are projected onto the multiple detector 222 via the detector aperture array substrate 228 by the secondary electron optical system 152 . Since the representative primary electron beam A14 does not irradiate the scan center, the scan center position of the representative secondary electron beam B14 deviates from the center of the detection area of the corresponding detection element D14. FIG. 20(b) shows a case where the scanning center position of the representative secondary electron beam B14 is shifted, for example, to the lower left side with respect to the center of the detection area of the detection element D14. In this state, the deflector 226 scans the currently set secondary beam scanning range for the multiple secondary electron beams 300 including the representative secondary electron beam.

As the secondary beam detection (image acquisition) step (S112), here, the scanned representative secondary electron beam B14 is detected for the upper left corner position of the representative primary beam deflection range. The example of FIG. 20(b) shows the case where the scanning width in the x and y directions of the secondary beam scanning range is set to a value four times the beam pitch. As a result, the corresponding detector element D14 captures an aperture image of the detector aperture array substrate 228 for a plurality of beams. Since the detection area is located on the upper right side with respect to the scan center of the representative secondary electron beam B14, as shown in FIG. The image will be located on the upper right side from the center of the image. Aperture images of the remaining detected secondary electron beams B13, B24, B23 are arranged at respective positions along the arrangement of the beam array. Since the representative secondary electron beam B14 is a corner beam, even if the aperture images of a plurality of secondary electron beams appear together, the corner aperture image can be identified as the aperture image of the representative secondary electron beam B14. A rectangular frame of the detected image indicates the secondary beam scanning range. A detected image of the representative secondary electron beam B14 is output to the image synthesizing circuit 138 .

FIG. 21 is a diagram for explaining an example of the position of the representative secondary electron beam when the upper right corner position of the scanning range of the primary electron beam is irradiated with the representative primary electron beam in the second embodiment. As shown in FIG. 21A, beam deflection by the sub-deflector 209 irradiates the representative primary electron beam A14 onto the upper right corner position of the scanning range.

In FIG. 21A, when the representative primary electron beam A14 irradiates the upper right corner position of the scanning range, a representative secondary electron beam B14 corresponding to the representative primary electron beam A14 is emitted from the stage 105. FIG. At the same time, secondary electron beams corresponding to each of the other primary electron beams are emitted from stage 105 . These multiple secondary electron beams 300 are projected onto the multiple detector 222 via the detector aperture array substrate 228 by the secondary electron optical system 152 . Since the representative primary electron beam A14 does not irradiate the scan center, the scan center position of the representative secondary electron beam B14 deviates from the center of the detection area of the corresponding detection element D14. FIG. 21(b) shows a case where the scan center position of the representative secondary electron beam B14 is shifted, for example, to the lower right side with respect to the center of the detection area of the detection element D14. In this state, the deflector 226 scans the currently set secondary beam scanning range for the multiple secondary electron beams 300 including the representative secondary electron beam.

As the secondary beam detection (image acquisition) step (S112), here, the scanned representative secondary electron beam B14 is detected for the upper right corner position of the representative primary beam deflection range. The example of FIG. 21(b) shows the case where the scanning width in the x and y directions of the secondary beam scanning range is set to a value four times the beam pitch. As a result, the corresponding detector element D14 captures an aperture image of the detector aperture array substrate 228 for a plurality of beams. Since the detection area is located on the upper right side with respect to the scan center of the representative secondary electron beam B14, as shown in FIG. The image will be located on the upper left side of the center of the image. Aperture images of the remaining detected secondary electron beams B11-B13 and B21-24 are arranged at respective positions along the arrangement of the beam array. Since the representative secondary electron beam B14 is a corner beam, even if the aperture images of a plurality of secondary electron beams appear together, the corner aperture image can be identified as the aperture image of the representative secondary electron beam B14. A rectangular frame of the detected image indicates the secondary beam scanning range. A detected image of the representative secondary electron beam B14 is output to the image synthesizing circuit 138 .

As the image synthesizing step (S120), the image synthesizing circuit 138 synthesizes the detection images of the representative secondary electron beam B14 detected for each of the plurality of positions in the primary beam deflection range. As a result, as shown in FIG. 13A, an example of a synthesized image obtained by synthesizing the aperture images captured at the four corner positions is obtained.

As described above, even when the primary electron beam is not limited to one beam, it is possible to obtain a synthesized image obtained by synthesizing the aperture images captured at the four corner positions.

Below, an image synthesizing step (S120), a coordinate obtaining step (S121), a secondary beam deflection condition calculation step (S122), a secondary beam deflection condition setting step (S124), and an inspection image obtaining step (S130). , the reference image creation step (S132), and the comparison step (S140) are the same as those in the first embodiment.

In the above example, the case where a synthetic image is created for one of the four corner beams and the secondary beam deflection condition is calculated was explained, but the present invention is not limited to this. Four corner beams of the multi-primary electron beam 20 are used as representative primary electron beams. Then, a composite image is created for each of the four corner beams. The secondary beam deflection conditions are calculated for each of the four corner beams. Then, for each parameter of the secondary beam deflection conditions, it is also preferable to obtain statistical values of values calculated for each beam. For example, find the average value. Alternatively, find the median value. As a result, errors can be reduced more than when calculating with one beam. Therefore, the accuracy of each parameter of the secondary beam deflection conditions can be improved.

As described above, according to the second embodiment, the multi-electron beam that cancels the positional movement of the multi-secondary electron beams accompanying the scanning of the multi-primary electron beams without limiting the number of primary electron beams to be irradiated to one. An image in which the deflection of the secondary electron beam is adjusted can be obtained.

In the above description, a series of "-circuits" includes processing circuits, and the processing circuits include electric circuits, computers, processors, circuit boards, quantum circuits, semiconductor devices, and the like. Also, each "-circuit" may use a common processing circuit (same processing circuit). Alternatively, different processing circuits (separate processing circuits) may be used. A program that causes a processor or the like to be executed may be recorded on a recording medium such as a magnetic disk device, magnetic tape device, FD, or ROM (Read Only Memory). For example, position position circuit 107, comparison circuit 108, reference image generation circuit 112, stage control circuit 114, lens control circuit 124, blanking control circuit 126, deflection control circuit 128, detector stage control circuit 130, beam position search circuit 134 , and the beam select aperture control circuit 136 may comprise at least one processing circuit as described above. For example, the processing within these circuits may be performed by the control computer 110 .

The embodiments have been described above with reference to specific examples. However, the invention is not limited to these specific examples. Although the example of FIG. 1 shows the case of forming the multiple primary electron beams 20 by the shaping aperture array substrate 203 from one beam irradiated from the electron gun 201 as one irradiation source, the present invention is limited to this. is not. A mode in which the multiple primary electron beams 20 are formed by irradiating primary electron beams from a plurality of irradiation sources may be employed.

In addition, descriptions of parts that are not directly necessary for the explanation of the present invention, such as the device configuration and control method, are omitted, but the required device configuration and control method can be appropriately selected and used.

In addition, all multi-charged particle beam alignment methods and multi-charged particle beam inspection apparatuses that have the elements of the present invention and that can be appropriately modified by those skilled in the art are included in the scope of the present invention.

8 Primary electron beam 11 Large aperture 13 Small aperture 20 Multi primary electron beam 21 Representative primary electron beam 22 Hole 29 Sub-irradiation area 30 Frame area 31 Frame image 32 Stripe area 33 Rectangular area 34 Irradiation areas 50, 52, 56 Storage Device 54 Frame image creating unit 57 Alignment unit 58 Comparison unit 60 Beam selection unit 61 Primary system scanning condition setting unit 62 Secondary system scanning condition setting unit 63 Corner position setting unit 64 Judging unit 65 Judging unit 66 Synthetic image acquiring unit 67 , 69 storage device 68 deflection condition calculation unit 70 coordinate acquisition unit 100 inspection device 101 substrate 102 electron beam column 103 inspection room 105 stage 106 detection circuit 107 position circuit 108 comparison circuit 109 storage device 110 control computer 111 mark 112 reference image creation circuit 114 Stage control circuit 117 Monitor 118 Memory 119 Printer 120 Bus 122 Laser length measurement system 123 Chip pattern memory 124 Lens control circuit 126 Blanking control circuit 128 Deflection control circuit 133 E×B control circuit 134 Deflection adjustment circuit 136 Beam selection aperture control circuit 138 Image synthesis circuit 142 Drive mechanisms 144, 146, 148, 149 DAC amplifier 150 Image acquisition mechanism 151 Primary electron optical system 152 Secondary electron optical system 160 Control system circuit 201 Electron gun 202 Electromagnetic lens 203 Shaped aperture array substrates 205, 206, 207, 224 electromagnetic lens 208 main deflector 209 sub-deflector 212 batch blanking deflector 213 limiting aperture substrate 214 E×B separator 216 mirror 218 deflector 222 multi-detector 226 deflector 228 detector aperture array substrate 232 beam selection Aperture substrate 234 Drive mechanism 300 Multi secondary electron beam 301 Representative secondary electron beam 330 Inspection region 332 Chip

A multi-electron beam image acquisition method according to one aspect of the present invention comprises:
a step of irradiating a representative primary electron beam selected from multiple primary electron beams onto a plurality of positions within a primary beam deflection range of a preset representative primary beam on a stage on which the substrate is placed;
Temporary secondary beam deflection using a representative secondary electron beam emitted from each position of a plurality of positions in the primary beam deflection range of the representative primary beam due to irradiation of the representative primary electron beam. scanning under conditions;
Predetermined detection elements of a multi-detector having a plurality of detection elements for representative secondary electron beams scanned under temporary secondary beam deflection conditions for each of a plurality of positions in a primary beam deflection range of the representative primary beam a step of detecting with
a step of acquiring a plurality of coordinates corresponding to a plurality of positions based on a detected image of the representative secondary electron beam detected for each position of a plurality of positions in a primary beam deflection range of the representative primary beam;
Using the plurality of acquired coordinates, the movement of the representative secondary electron beam due to the movement of the representative primary electron beam within the primary beam deflection range of the representative primary beam is offset, and the movement of the representative secondary electron beam to the predetermined detection element is determined. calculating a secondary beam deflection condition so that the irradiation position of the representative secondary electron beam is fixed;
The substrate placed on the stage is scanned using the multi primary electron beams in the primary electron beam deflection range of the multi primary electron beams, and the substrate is deflected according to the calculated secondary beam deflection conditions. obtaining a secondary electron image of the substrate by detecting the multiple secondary electron beams with a multiple detector while scanning with the multiple secondary electron beams emitted from the substrate;
characterized by comprising

Moreover, it is preferable to use four corner positions of the primary electron beam deflection range of the representative primary beam as the plurality of positions.

The method further comprises a step of synthesizing detection images of representative secondary electron beams detected for each of a plurality of positions in a primary beam deflection range of the representative primary beam,
Preferably, the multiple coordinates are obtained using the combined composite image.

A multi-electron beam image acquisition device according to one aspect of the present invention comprises:
a stage on which the substrate is placed;
a primary system deflector for irradiating a representative primary electron beam selected from multiple primary electron beams onto a plurality of positions within a primary beam deflection range of a preset representative primary beam on a stage;
For each position of a plurality of positions in the primary beam deflection range of the representative primary beam, the representative secondary electron beam emitted from the position due to the irradiation of the representative primary electron beam is measured under a temporary secondary beam deflection condition. a secondary system deflector for scanning;
a representative secondary electron beam scanned under a temporary secondary beam deflection condition for each of a plurality of positions in a primary beam deflection range of the representative primary beam; A multi-detector that detects with a detection element of
a coordinate acquisition unit that acquires a plurality of coordinates corresponding to a plurality of positions based on a detected image of the representative secondary electron beam detected for each of a plurality of positions in a primary beam deflection range of the representative primary beam;
Using the plurality of acquired coordinates, the movement of the representative secondary electron beam due to the movement of the representative primary electron beam within the primary beam deflection range of the representative primary beam is offset, and the movement of the representative secondary electron beam to the predetermined detection element is determined. a deflection condition calculation unit that calculates a secondary beam deflection condition so that the irradiation position of the representative secondary electron beam is fixed;
with
The substrate placed on the stage is scanned by the primary system deflector using the multiple primary electron beams within the primary electron beam deflection range of the multiple primary electron beams, and the calculated secondary beam deflection conditions are satisfied. A secondary electron image of the substrate is obtained by detecting the multi-secondary electron beams with a multi-detector while scanning using the multi-secondary electron beams emitted from the substrate by beam deflection by a secondary system deflector. characterized by obtaining

A multi-electron beam inspection apparatus according to one aspect of the present invention includes
a stage on which the substrate is placed;
a primary system deflector for irradiating a representative primary electron beam selected from multiple primary electron beams onto a plurality of positions within a primary beam deflection range of a preset representative primary beam on a stage;
Temporary secondary beam deflection using a representative secondary electron beam emitted from each position of a plurality of positions in the primary beam deflection range of the representative primary beam due to irradiation of the representative primary electron beam. a secondary system deflector that scans under conditions;
a representative secondary electron beam scanned under a temporary secondary beam deflection condition for each of a plurality of positions in a primary beam deflection range of the representative primary beam; A multi-detector that detects with a detection element of
a coordinate acquisition unit that acquires a plurality of coordinates corresponding to a plurality of positions based on a detected image of the representative secondary electron beam detected for each of a plurality of positions in a primary beam deflection range of the representative primary beam;
Using the plurality of acquired coordinates, the movement of the representative secondary electron beam due to the movement of the representative primary electron beam within the primary beam deflection range of the representative primary beam is offset, and the movement of the representative secondary electron beam to the predetermined detection element is determined. a deflection condition calculation unit that calculates a secondary beam deflection condition so that the irradiation position of the representative secondary electron beam is fixed;
with
The substrate placed on the stage is scanned by the primary system deflector using the multiple primary electron beams within the primary electron beam deflection range of the multiple primary electron beams, and the calculated secondary beam deflection conditions are satisfied. A secondary electron image of the substrate is acquired by detecting the multiple secondary electron beams with the multiple detectors while scanning using the multiple secondary electron beams emitted from the substrate by the beam deflection by the secondary system deflector. death,
It is characterized by further comprising a comparison unit that compares at least part of the obtained secondary electron image with a predetermined image.

A multi-electron beam image acquisition device according to another aspect of the present invention comprises:
a stage on which the substrate is placed;
a primary system deflector for sequentially irradiating a representative primary electron beam representing the multiple primary electron beams onto a plurality of positions within a primary beam deflection range of the representative primary beam set in advance on the stage at staggered times; ,
Temporary secondary beam deflection using a representative secondary electron beam emitted from each position of a plurality of positions in the primary beam deflection range of the representative primary beam due to irradiation of the representative primary electron beam. a secondary system deflector that scans under conditions;
a representative secondary electron beam scanned under a temporary secondary beam deflection condition for each of a plurality of positions in a primary beam deflection range of the representative primary beam; A multi-detector that detects with a detection element of
an image synthesizing unit for synthesizing detection images of representative secondary electron beams detected for each of a plurality of positions in a primary beam deflection range of the representative primary beam;
Using the synthesized composite image, the movement of the representative secondary electron beam due to the movement of the representative primary electron beam within the primary beam deflection range of the representative primary beam is canceled, and the representative to the predetermined detection element is obtained. a deflection condition calculation unit that calculates a secondary beam deflection condition so that the irradiation position of the secondary electron beam is fixed;
with
The substrate placed on the stage is scanned by the primary system deflector using the multiple primary electron beams within the primary electron beam deflection range of the multiple primary electron beams, and the calculated secondary beam deflection conditions are satisfied. A secondary electron image of the substrate is acquired by detecting the multiple secondary electron beams with the multiple detectors while scanning using the multiple secondary electron beams emitted from the substrate by the beam deflection by the secondary system deflector. characterized by

A multi-electron beam inspection apparatus according to another aspect of the present invention comprises:
a stage on which the substrate is placed;
a primary system deflector for sequentially irradiating a representative primary electron beam representing the multiple primary electron beams onto a plurality of positions within a primary beam deflection range of the representative primary beam set in advance on the stage at staggered times; ,
Temporary secondary beam deflection using a representative secondary electron beam emitted from each position of a plurality of positions in the primary beam deflection range of the representative primary beam due to irradiation of the representative primary electron beam. a secondary system deflector that scans under conditions;
a representative secondary electron beam scanned under a temporary secondary beam deflection condition for each of a plurality of positions in a primary beam deflection range of the representative primary beam; A multi-detector that detects with a detection element of
an image synthesizing unit for synthesizing detection images of representative secondary electron beams detected for each of a plurality of positions in a primary beam deflection range of the representative primary beam;
Using the synthesized composite image, the movement of the representative secondary electron beam due to the movement of the representative primary electron beam within the primary beam deflection range of the representative primary beam is canceled, and the representative to the predetermined detection element is obtained. a deflection condition calculation unit that calculates a secondary beam deflection condition so that the irradiation position of the secondary electron beam is fixed;
with
The substrate placed on the stage is scanned by the primary system deflector using the multiple primary electron beams within the primary electron beam deflection range of the multiple primary electron beams, and the calculated secondary beam deflection conditions are satisfied. A secondary electron image of the substrate is acquired by detecting the multiple secondary electron beams with the multiple detectors while scanning using the multiple secondary electron beams emitted from the substrate by the beam deflection by the secondary system deflector. death,
It is characterized by further comprising a comparison unit that compares at least part of the obtained secondary electron image with a predetermined image.

Claims (12)

a step of irradiating a representative primary electron beam selected from the multiple primary electron beams onto a plurality of positions within a preset primary beam deflection range on a stage on which the substrate is placed;
For each of the plurality of positions in the representative primary beam deflection range, the representative secondary electron beam emitted from the position due to the irradiation of the representative primary electron beam is scanned under a temporary secondary beam deflection condition. and
the representative secondary electron beam scanned under a temporary secondary beam deflection condition at each of the plurality of positions in the representative primary beam deflection range using predetermined detection elements of a multi-detector having a plurality of detection elements; a step of detecting;
obtaining a plurality of coordinates corresponding to the plurality of positions based on the detected image of the representative secondary electron beam detected for each of the plurality of positions in the primary beam deflection range;
Movement of the representative secondary electron beam due to movement of the representative primary electron beam within the primary beam deflection range is offset using the acquired plurality of coordinates, and the movement of the representative secondary electron beam to the predetermined detection element is compensated. calculating a secondary beam deflection condition so that the irradiation position of the representative secondary electron beam is fixed;
The substrate placed on the stage is scanned using the multiple primary electron beams within the primary electron beam deflection range, and the beam is deflected in accordance with the calculated secondary beam deflection conditions, thereby scanning the substrate. acquiring a secondary electron image of the substrate by detecting the multi-secondary electron beams with the multi-detector while scanning the emitted multi-secondary electron beams;
A multi-electron beam image acquisition method comprising: 2. A multi-electron beam image acquisition method according to claim 1, wherein positions at four corners of said primary electron beam deflection range are used as said plurality of positions. 3. A multi-electron beam image acquisition method according to claim 1, wherein the deflection conditions of said secondary electron beams include a deflection magnification and a deflection rotation angle. 4. The multi-electron beam image acquiring method according to claim 1, wherein a center beam of multi-primary electron beams is used as the representative primary electron beam. Using four corner beams of the multi-primary electron beam as the representative primary electron beam,
4. The multi-electron system according to claim 1, wherein the secondary beam deflection conditions are calculated for each of the four corner beams, and statistical values of values calculated for each beam are used. Beam image acquisition method. further comprising the step of synthesizing detection images of the representative secondary electron beam detected for each of the plurality of positions in the primary beam deflection range;
6. The multi-electron beam image acquiring method according to claim 1, wherein said plurality of coordinates are acquired using a synthesized composite image. 2. The method of claim 1, further comprising selecting a representative primary electron beam from the multiple primary electron beams and shielding the remaining beams. When irradiating the plurality of positions with the representative primary electron beam, irradiating the remaining unselected beams together;
Aperture images of the plurality of secondary electron beams appear together in the detection image of the representative secondary electron beam detected for each of the plurality of positions,
2. The representative secondary electron beam is identified from among the plurality of aperture images of the secondary electron beams using a detection image in which the aperture images of the plurality of secondary electron beams are captured together. A multi-electron beam image acquisition method as described. a stage on which the substrate is placed;
a primary system deflector that irradiates a representative primary electron beam selected from multiple primary electron beams onto a plurality of positions within a preset primary beam deflection range on the stage;
For each of the plurality of positions in the representative primary beam deflection range, the representative secondary electron beam emitted from the position due to the irradiation of the representative primary electron beam is scanned under a temporary secondary beam deflection condition. a secondary system deflector that
a plurality of detection elements, wherein the representative secondary electron beam scanned under a temporary secondary beam deflection condition is detected by the plurality of detection elements for each of the plurality of positions in the representative primary beam deflection range; A multi-detector that detects with a detection element of
a coordinate acquisition unit configured to acquire a plurality of coordinates corresponding to the plurality of positions based on the detected image of the representative secondary electron beam detected for each of the plurality of positions in the primary beam deflection range;
Movement of the representative secondary electron beam due to movement of the representative primary electron beam within the primary beam deflection range is offset using the acquired plurality of coordinates, and the movement of the representative secondary electron beam to the predetermined detection element is compensated. a deflection condition calculation unit that calculates a secondary beam deflection condition so that the irradiation position of the representative secondary electron beam is fixed;
with
The substrate placed on the stage is scanned by the primary system deflector using the multiple primary electron beams in the primary electron beam deflection range, and the secondary beam deflection conditions are calculated. A secondary electron image of the substrate is obtained by detecting the multiple secondary electron beams with the multiple detector while scanning the multiple secondary electron beams emitted from the substrate by beam deflection by the secondary system deflector. A multi-electron beam image acquisition device characterized by acquiring a stage on which the substrate is placed;
a primary system deflector that irradiates a representative primary electron beam selected from multiple primary electron beams onto a plurality of positions within a preset primary beam deflection range on the stage;
For each of the plurality of positions in the representative primary beam deflection range, the representative secondary electron beam emitted from the position due to the irradiation of the representative primary electron beam is scanned under a temporary secondary beam deflection condition. a secondary system deflector that
a plurality of detection elements, wherein the representative secondary electron beam scanned under a temporary secondary beam deflection condition is detected by the plurality of detection elements for each of the plurality of positions in the representative primary beam deflection range; A multi-detector that detects with a detection element of
a coordinate acquisition unit configured to acquire a plurality of coordinates corresponding to the plurality of positions based on the detected image of the representative secondary electron beam detected for each of the plurality of positions in the primary beam deflection range;
Movement of the representative secondary electron beam due to movement of the representative primary electron beam within the primary beam deflection range is offset using the acquired plurality of coordinates, and the movement of the representative secondary electron beam to the predetermined detection element is compensated. a deflection condition calculation unit that calculates a secondary beam deflection condition so that the irradiation position of the representative secondary electron beam is fixed;
with
The substrate placed on the stage is scanned by the primary system deflector using the multiple primary electron beams in the primary electron beam deflection range, and the secondary beam deflection conditions are calculated. A secondary electron image of the substrate is obtained by detecting the multiple secondary electron beams with the multiple detector while scanning the multiple secondary electron beams emitted from the substrate by beam deflection by the secondary system deflector. and get
A multi-electron beam inspection apparatus, further comprising a comparison unit that compares at least a part of the obtained secondary electron image with a predetermined image. a stage on which the substrate is placed;
a primary system deflector for sequentially irradiating representative primary electron beams representing multiple primary electron beams onto a plurality of positions within a preset primary beam deflection range on the stage at different times;
For each of the plurality of positions in the representative primary beam deflection range, the representative secondary electron beam emitted from the position due to the irradiation of the representative primary electron beam is scanned under a temporary secondary beam deflection condition. a secondary system deflector that
a plurality of detection elements, wherein the representative secondary electron beam scanned under a temporary secondary beam deflection condition is detected by the plurality of detection elements for each of the plurality of positions in the representative primary beam deflection range; A multi-detector that detects with a detection element of
an image synthesizing unit for synthesizing detection images of the representative secondary electron beam detected for each of the plurality of positions in the primary beam deflection range;
Using the synthesized composite image, movement of the representative secondary electron beam due to movement of the representative primary electron beam within the range of primary beam deflection is offset, and the representative electron beam to the predetermined detector element is detected. a deflection condition calculation unit that calculates a secondary beam deflection condition so that the irradiation position of the secondary electron beam is fixed;
with
The substrate placed on the stage is scanned by the primary system deflector using the multiple primary electron beams in the primary electron beam deflection range, and the secondary beam deflection conditions are calculated. A secondary electron image of the substrate is obtained by detecting the multiple secondary electron beams with the multiple detector while scanning the multiple secondary electron beams emitted from the substrate by beam deflection by the secondary system deflector. A multi-electron beam image acquisition device characterized by acquiring a stage on which the substrate is placed;
a primary system deflector for sequentially irradiating representative primary electron beams representing multiple primary electron beams onto a plurality of positions within a preset primary beam deflection range on the stage at different times;
For each of the plurality of positions in the representative primary beam deflection range, the representative secondary electron beam emitted from the position due to the irradiation of the representative primary electron beam is scanned under a temporary secondary beam deflection condition. a secondary system deflector that
a plurality of detection elements, wherein the representative secondary electron beam scanned under a temporary secondary beam deflection condition is detected by the plurality of detection elements for each of the plurality of positions in the representative primary beam deflection range; A multi-detector that detects with a detection element of
an image synthesizing unit for synthesizing detection images of the representative secondary electron beam detected for each of the plurality of positions in the primary beam deflection range;
Using the synthesized composite image, movement of the representative secondary electron beam due to movement of the representative primary electron beam within the range of primary beam deflection is offset, and the representative electron beam to the predetermined detector element is detected. a deflection condition calculation unit that calculates a secondary beam deflection condition so that the irradiation position of the secondary electron beam is fixed;
with
The substrate placed on the stage is scanned by the primary system deflector using the multiple primary electron beams in the primary electron beam deflection range, and the secondary beam deflection conditions are calculated. A secondary electron image of the substrate is obtained by detecting the multiple secondary electron beams with the multiple detector while scanning the multiple secondary electron beams emitted from the substrate by beam deflection by the secondary system deflector. and get
A multi-electron beam inspection apparatus, further comprising a comparison unit that compares at least a part of the obtained secondary electron image with a predetermined image.

Images