JP6664223B2 - Electron gun and inspection device having the same - Google Patents

Description

  The present invention relates to an inspection apparatus for inspecting a defect or the like of a pattern formed on a surface of an inspection object and an electron gun that can be used in the inspection apparatus.

  The conventional semiconductor inspection device is a device and technology corresponding to the 100 nm design rule. However, the specimens to be inspected are diversified into wafers, exposure masks, EUV masks, NIL (nanoimprint lithography) masks and substrates, and currently, devices and techniques that are compatible with design rules of 5 to 30 nm are required. ing. In other words, there is a demand for a generation in which patterns have L / S (line / space) or hp (half pitch) nodes of 5 to 30 nm. When inspecting such a sample with an inspection device, it is necessary to obtain high resolution.

  Here, the sample is an exposure mask, an EUV mask, a nanoimprint mask (and a template), a semiconductor wafer, an optical element substrate, an optical circuit substrate, and the like. These include those having a pattern and those without a pattern. Some have a pattern, and some have a pattern. The pattern without unevenness is formed by a different material. Those having no pattern include those coated with an oxide film and those not coated with an oxide film.

  As a conventional semiconductor inspection device, by controlling the movement of the sample accompanying the continuous movement of the stage and the deflection of the trajectory of the secondary beam by the deflecting means in synchronization, the image of the secondary beam on the two-dimensional CCD sensor is controlled. There is known an electron beam inspection apparatus using an electron image-following type electron optical device in which an image of the same detection area of a sample is projected to the same place of a two-dimensional CCD sensor during the synchronization period. (For example, see Patent Document 1).

Japanese Patent No. 4333222

  If the inspection apparatus cannot irradiate a uniform electron beam from the electron gun, the inspection may not be performed with high accuracy.

  The present invention has been devised in view of the above problems and effectively solving them. An object of the present invention is to provide an inspection device capable of performing an inspection with high accuracy and an electron gun that can be used in such an inspection device.

According to one embodiment of the present invention, a light source that emits light, an optical deflector that deflects light from the light source, an optical deflector whose amount of deflection is time-modulated, and an electronic deflector that deflects the deflected light An electron gun is provided, comprising: a photoelectric conversion surface that converts the light into a beam; and an electron beam deflector that deflects the electron beam from the photoelectric conversion surface toward a predetermined point.
According to this aspect, since the light from the light source is deflected by providing the optical deflector and the amount of deflection is time-modulated, the light is scattered over a wide position on the photoelectric conversion surface and irradiated. Therefore, even when the irradiation efficiency of the photoelectric conversion surface is not uniform, the electron beam is uniformly irradiated.

The light deflector has a first light modulator that deflects the light in a first direction, and a second light modulator that deflects the light in a second direction. The apparatus may include a first electron beam deflector for deflecting the electron beam in the first direction, and a second electron beam deflector for deflecting the electron beam in the second direction.
Thus, light can be modulated in two directions.

The first electron beam deflector deflects the electron beam in the first direction so that light deflection by the first light modulator is canceled, and the second electron beam deflector includes a second light beam deflector. Preferably, the electron beam is deflected in the second direction so that the light deflection by the modulator is canceled.
Thereby, the amount of light deflected in the first direction by the first electron beam deflector can be canceled by the first electron beam deflector, and the amount of light deflected in the second direction by the second electron beam deflector can be reduced. , The second electron beam deflector, and the electron beam can be accurately guided to a predetermined point.

The amount of deflection by the first optical modulator and the amount of deflection by the first electron beam deflector are controlled synchronously, and the amount of deflection by the second optical modulator and the amount of deflection by the second electron beam deflector are controlled. It is desirable to provide a control unit that controls the amount of deflection in synchronization with the amount of deflection.
By performing such a synchronous control, the electron beam can be accurately guided to a predetermined point.

As a specific example, the control unit synchronously controls both the amount of deflection by the first optical modulator and the amount of deflection by the first electron beam deflector based on a first reference signal having a predetermined frequency. Based on the second reference signal, both the amount of deflection by the second optical modulator and the amount of deflection by the second electron beam deflector may be synchronously controlled.
By controlling both the first optical modulator and the first electron beam deflector using the first reference signal, both can be synchronously controlled, and the second optical modulator and the second electron beam deflector can be controlled using the second reference signal. By controlling both devices, both can be controlled synchronously.

As still another specific example, the control unit receives a signal corresponding to the deflection amount from the first optical modulator, and controls the deflection amount of the first electron beam deflector based on the signal, A signal corresponding to the deflection amount may be received from the second optical modulator, and the deflection amount of the second electron beam deflector may be controlled based on the signal.
According to this configuration, since the first electron beam deflector is controlled based on the signal from the first optical modulator, both can be synchronized. Similarly, since the second electron beam deflector is controlled based on the signal from the second optical modulator, both can be synchronized.

  The optical deflector may include any of a galvanometer mirror, a polygon mirror, and an AO deflector.

According to another aspect of the present invention, a stage device on which a sample is placed and continuously moved, the electron gun for irradiating an electron beam, and the stage device using an electron beam from the electron gun as a primary beam A primary optical system leading to the sample, a detector including a two-dimensional sensor that generates an image of a secondary beam generated from the sample by irradiating the sample with the primary beam, and An inspection device is provided, which is provided with a secondary optical system leading to the two-dimensional sensor.
By using such an electron gun, the electron beam is uniformly irradiated, so that the inspection accuracy is improved.

  According to the present invention, since a uniform electron beam is emitted from the electron gun, the inspection can be performed with high accuracy.

It is an elevational view showing the main components of the inspection device concerning one embodiment of the present invention. FIG. 2 is a plan view of main components of the inspection apparatus shown in FIG. 1, as viewed along a line BB in FIG. 1. FIG. 1 is a diagram illustrating a configuration of an electron optical device according to an embodiment of the present invention. FIG. 4 is a diagram for explaining a beam path in the electron optical device shown in FIG. 3. (A) It is a figure explaining operation of a high-speed deflector which deflects a secondary beam so that a secondary beam may follow a sample movement concerning one embodiment of the present invention. FIG. 3B is a diagram illustrating a relationship between an irradiation area and a viewing area according to an embodiment of the present invention. (C) is a diagram showing a relationship between an irradiation area and a viewing area according to an embodiment of the present invention. It is a figure showing composition of a combination unit of a high-speed deflector, an imaging lens, and an intermediate electrode concerning one embodiment of the present invention. FIG. 4 is a flowchart showing the operation of the simulation device according to one embodiment of the present invention. FIG. 2 is a block diagram schematically showing a schematic configuration of an electron gun 721. The perspective view of a galvanometer mirror.

Hereinafter, an inspection apparatus according to an embodiment of the present invention will be described with reference to the drawings. The embodiment described below shows an example in which the present invention is implemented, and the present invention is not limited to the specific configuration described below. In carrying out the present invention, a specific configuration according to the embodiment may be appropriately adopted.
1 and 2, main components of the inspection apparatus 1 according to the present embodiment are shown in an elevation and a plane.

  The inspection apparatus 1 according to the present embodiment includes a cassette holder 10 that holds a cassette containing a plurality of samples, a mini-environment device 20, a main housing 30 that defines a working chamber, a mini-environment device 20, A loader housing 40 disposed between the housing 30 and defining two loading chambers; a loader 60 for loading a sample from the cassette holder 10 onto a stage device 50 disposed in the main housing 30; An electron optical device 70 attached to the housing 30, an optical microscope 3000, and a scanning electron microscope (SEM) 3002 are arranged in a positional relationship as shown in FIGS. The inspection apparatus 1 further includes a precharge unit 81 disposed in the vacuum main housing 30, a potential application mechanism for applying a potential to the sample, an electron beam calibration mechanism, and positioning of the sample on the stage device 50. And an optical microscope 871 that constitutes an alignment control device 87 for performing the operation.

  Here, the sample is an exposure mask, an EUV mask, a nanoimprint mask (and a template), a semiconductor wafer, an optical element substrate, an optical circuit substrate, and the like. These include those having a pattern and those without a pattern. Some have a pattern, and some have a pattern. The pattern without unevenness is formed by a different material. Those having no pattern include those coated with an oxide film and those not coated with an oxide film.

<Cassette holder>
The cassette holder 10 includes a plurality of cassettes c (for example, closed cassettes such as SMIF and FOUP manufactured by Assist Co., Ltd.) in which a plurality of (for example, 25) samples are stored in a state of being vertically arranged in parallel. In this embodiment, two are held. As the cassette holder, one having a structure suitable for transporting a cassette by a robot or the like and automatically loading the cassette into the cassette holder 10, and one having an open cassette structure suitable for manual loading when the cassette is loaded manually. Can be arbitrarily selected and installed. In this embodiment, the cassette holder 10 is of a type in which the cassette c is automatically loaded, and includes, for example, an elevating table 11 and an elevating mechanism 12 for moving the elevating table 11 up and down. 2 can be automatically set in a state shown by a chain line in FIG. 2, and after setting, it is automatically rotated to a state shown in a solid line in FIG. Pointed at the pivot axis. Further, the lifting table 11 is lowered to a state shown by a chain line in FIG. As described above, the cassette holder used for automatic loading or the cassette holder used for manual loading may be appropriately configured with a known structure. Description is omitted.

  Note that the sample stored in the cassette c is a sample to be inspected, and such an inspection is performed after a process of processing a sample in a semiconductor manufacturing process or during the process. Specifically, a sample that has undergone a film forming process, CMP, ion implantation, or the like, a sample having a pattern formed on its surface, or a sample having no pattern formed thereon is stored in a cassette. Since a large number of samples accommodated in the cassette c are arranged side by side in parallel at a distance in the up-down direction, the first transport unit 61 can hold the sample at an arbitrary position so that the first transport unit 61 can hold the sample. Arm 612 can be moved up and down.

<Mini-environment device>
1 and 2, a mini-environment device 20 includes a housing 22 defining a mini-environment space 21 that is controlled in atmosphere, and a gas such as clean air in the mini-environment space 21. A gas circulating device 23 for circulating and controlling the atmosphere, a discharging device 24 for collecting and discharging a part of the air supplied into the mini-environment space 21, and a gas circulating device 23 are provided in the mini-environment space 21. And a pre-aligner 25 for roughly positioning the sample to be inspected.

  The housing 22 has a top wall 221, a bottom wall 222, and a peripheral wall 223 surrounding four circumferences, and has a structure that blocks the mini-environment space 21 from the outside. In order to control the atmosphere of the mini-environment space, the gas circulation device 23 is attached to the top wall 221 in the mini-environment space 21 and cleans one or more of the gases (air in this embodiment). A gas supply unit 231 for flowing clean air in a laminar flow directly downward through the above gas outlets (not shown), and a gas supply unit 231 disposed on the bottom wall 222 in the mini-environment space 21 and facing the bottom. And a conduit 233 connecting the collection duct 232 and the gas supply unit 231 to return the collected air to the gas supply unit 231. In this embodiment, the gas supply unit 231 takes in about 20% of the supplied air from the outside of the housing 22 for cleaning, but the ratio of the gas taken in from the outside can be arbitrarily selected. . The gas supply unit 231 includes a HEPA or ULPA filter having a known structure for producing clean air. The laminar downward flow or downflow of the clean air is mainly supplied to flow through the transport surface of the first transport unit 61 disposed in the mini-environment space 21, and is generated by the transport unit. Dust that can be prevented from adhering to the sample is prevented. Therefore, the downflow jet port does not necessarily need to be located at a position close to the top wall as shown in the figure, but may be located above the transport surface of the transport unit. Also, there is no need to flow over the entire mini-environment space. In some cases, cleanliness can be ensured by using ion wind as clean air. Further, a sensor for observing cleanliness may be provided in the mini-environment space, and the apparatus may be shut down when the cleanliness deteriorates. An entrance 225 is formed in a portion of the peripheral wall 223 of the housing 22 adjacent to the cassette holder 10. A shutter device having a known structure may be provided near the entrance 225 to close the entrance 225 from the mini-environment device side. The down flow of the laminar flow created near the sample may be, for example, a flow rate of 0.3 to 0.4 m / sec. The gas supply unit may be provided outside the mini-environment space 21 instead of inside.

  The discharge device 24 includes a suction duct 241 disposed below the first transport unit 61 at a position below the sample transport surface of the first transport unit 61, and a blower (not shown) disposed outside the housing 22. And a conduit (not shown) for connecting the suction duct 241 and the blower. The discharge device 24 flows down around the first transport unit 61, sucks dust-containing gas that may be generated by the first transport unit 61 by the suction duct 241, and passes through the conduit and the blower. And discharged to the outside of the housing 22. In this case, the air may be discharged into an exhaust pipe (not shown) drawn near the housing 22.

  The pre-aligner 25 disposed in the mini-environment space 21 includes an orientation flat (referred to as a flat portion formed on the outer periphery of a circular sample, hereinafter referred to as an orientation flat) formed on the sample and an outer peripheral edge of the sample. One or more V-shaped notches or notches are optically or mechanically detected to pre-position the rotational position of the sample around the axis OO with an accuracy of about ± 1 degree. Is to be kept. The pre-aligner 25 constitutes a part of a mechanism for determining coordinates of the inspection target, and is responsible for coarse positioning of the inspection target. Since the pre-aligner 25 itself may have a known structure, a description of its structure and operation will be omitted.

  Although not shown, a collection duct for a discharge device may be provided below the pre-aligner 25 to discharge air containing dust discharged from the pre-aligner 25 to the outside.

<Main housing>
1 and 2, a main housing 30 that defines a working chamber 31 includes a housing main body 32, which is mounted on a vibration isolator or vibration isolator 37 disposed on a base frame 36. It is supported by the mounted housing support device 33. The housing support device 33 includes a rectangular frame structure 331. The housing body 32 is disposed and fixed on the frame structure 331, and has a bottom wall 321 mounted on the frame structure 331, a top wall 322, and a peripheral wall connected to the bottom wall 321 and the top wall 322 and surrounding four circumferences. 323 to isolate the working chamber 31 from the outside. In this embodiment, the bottom wall 321 is formed of a relatively thick steel plate so as not to generate a distortion due to a load by a device such as the stage device 50 mounted thereon. Is also good. In this embodiment, the housing body 32 and the housing support device 33 are assembled in a rigid structure, and the vibration from the floor on which the base frame 36 is installed is transmitted to the rigid structure by the vibration isolator 37. It is designed to block. On the peripheral wall 323 of the housing main body 32 adjacent to a loader housing, which will be described later, an entrance 325 for taking in and out the sample is formed.

  The vibration isolator 37 may be an active type having an air spring, a magnetic bearing, or the like, or a passive type having these components. Since each of them may have a known structure, the description of the structure and function of itself is omitted. The working chamber 31 is maintained in a vacuum atmosphere by a vacuum device (not shown) having a known structure. The control device 2 for controlling the operation of the entire apparatus is arranged below the base frame 36.

<Loader housing>
1 and 2, the loader housing 40 includes a housing body 43 that defines a first loading chamber 41 and a second loading chamber 42. The housing main body 43 has a bottom wall 431, a top wall 432, a peripheral wall 433 surrounding four circumferences, and a partition wall 434 for partitioning the first loading chamber 41 and the second loading chamber 42. Can be isolated from the outside. The partition wall 434 has an opening, ie, an entrance 435, for exchanging the sample between the two loading chambers. Entrance ports 436 and 437 are formed in a portion of the peripheral wall 433 adjacent to the mini-environment device and the main housing. The housing body 43 of the loader housing 40 is mounted on and supported by the frame structure 331 of the housing support device 33. Therefore, vibration of the floor is not transmitted to the loader housing 40. The doorway 436 of the loader housing 40 and the doorway 226 of the housing 22 of the mini-environment device 20 are aligned, and there is a shutter for selectively blocking communication between the mini-environment space 21 and the first loading chamber 41. A device 27 is provided. The shutter device 27 includes a sealing member 271 that is fixed in close contact with the peripheral wall 433 around the entrances 226 and 436, and a door 272 that prevents air from flowing through the entrance in cooperation with the sealing member 271. And a driving device 273 for moving the door. The entrance 437 of the loader housing 40 and the entrance 325 of the housing body 32 are aligned with each other, and a shutter device 45 for selectively preventing the communication between the second loading chamber 42 and the working chamber 31 from being sealed is provided. Have been. The shutter device 45 surrounds the entrances 437 and 325 and closely contacts the peripheral walls 433 and 323 to seal and fix the sealing material 451 to the peripheral walls 433 and 323. The shutter 451 cooperates with the sealant 451 to flow air through the entrance and exit. It has a door 452 for blocking and a driving device 453 for moving the door. Further, the opening formed in the partition wall 434 is provided with a shutter device 46 which is closed by a door 461 and selectively prevents the communication between the first and second loading chambers from being sealed. These shutter devices 27, 45 and 46 are adapted to hermetically seal each chamber when in the closed state. Since these shutter devices may be known ones, detailed description of their structures and operations is omitted. The method of supporting the housing 22 of the mini-environment device 20 is different from the method of supporting the loader housing, and prevents the vibration from the floor from being transmitted to the loader housing 40 and the main housing 30 via the mini-environment device 20. For this purpose, a cushioning material for vibration isolation may be disposed between the housing 22 and the loader housing 40 so as to hermetically surround the entrance.

  In the first loading chamber 41, a sample rack 47 that supports a plurality (two in the present embodiment) of samples in a horizontal state with a vertical space therebetween is provided. The sample rack 47 includes columns fixed at four corners of a rectangular substrate 471 in an upright state with a distance from each other. Each column 472 has a two-stage support portion, and the peripheral portion of the sample W is placed on the support portion. Is placed and held. The distal ends of the arms of the first and second transfer units, which will be described later, approach the sample from between adjacent columns, and the sample is gripped by the arm.

The atmosphere of the loading chambers 41 and 42 can be controlled to a high vacuum state (the degree of vacuum is 10 ^-5 to 10 ^-6 Pa) by a vacuum exhaust device (not shown) having a known structure including a vacuum pump (not shown). Has become. In this case, the first loading chamber 41 is maintained in a low vacuum atmosphere as a low vacuum chamber, and the second loading chamber 42 is maintained in a high vacuum atmosphere as a high vacuum chamber, thereby effectively preventing contamination of the sample. By adopting such a structure, the sample accommodated in the loading chambers 41 and 42 and subjected to the next defect inspection can be transferred into the working chamber 31 without delay. By adopting such loading chambers 41 and 42, the throughput of the defect inspection is improved, and further, the degree of vacuum around the laser light source, which is required to be kept in a high vacuum state, is reduced to the highest possible vacuum state. Can be

  A vacuum exhaust pipe and a vent pipe (not shown) for an inert gas (for example, dry pure nitrogen) are connected to the first and second loading chambers 41 and 42, respectively. Thereby, the atmospheric pressure state in each loading chamber is achieved by an inert gas vent (injecting an inert gas to prevent oxygen gas and the like other than the inert gas from adhering to the surface). Since the apparatus itself for performing such inert gas venting may have a known structure, a detailed description thereof will be omitted.

<Stage device>
The stage device 50 includes a fixed table 51 disposed on a bottom wall 321 of the main housing 30, a Y table 52 that moves in the Y direction (a direction perpendicular to the paper surface in FIG. 1) on the fixed table, and a Y table 52 that moves on the Y table. An X table 53 that moves in the X direction (the horizontal direction in FIG. 1), a rotary table 54 that can rotate on the X table, and a holder 55 that is disposed on the rotary table 54 are provided. The sample is releasably held on the sample mounting surface 551 of the holder 55. The holder may have a known structure capable of releasably holding the sample mechanically or by an electrostatic chuck method. The stage device 50 operates the plurality of tables as described above by using a servomotor, an encoder, and various sensors (not shown), so that the sample held by the holder on the mounting surface 551 is electro-optically moved. The electron beam emitted from the device 70 can be positioned with high accuracy in the X direction, the Y direction, and the Z direction (vertical direction in FIG. 1) and further around the vertical axis (the θ direction) on the support surface of the sample. It has become. The positioning in the Z direction may be performed, for example, so that the position of the mounting surface on the holder can be finely adjusted in the Z direction. In this case, the reference position of the mounting surface is detected by a position measuring device (laser interferometer using the principle of an interferometer) using a fine-diameter laser, and the position is controlled by a feedback circuit (not shown), or together with the feedback circuit. Instead, the position of the notch or the orientation flat of the sample is measured, the plane position and the rotation position of the sample with respect to the electron beam are detected, and the rotation table is controlled by being rotated by a stepping motor capable of controlling a small angle. The servo motors 521 and 531 and the encoders 522 and 532 for the stage device 50 are arranged outside the main housing 30 in order to minimize generation of dust in the working chamber. The stage device 50 may have a known structure used in, for example, a stepper, and a detailed description of its structure and operation will be omitted. Further, since the laser interference distance measuring device may have a known structure, detailed description of its structure and operation will be omitted.

  By inputting the rotation position and the X and Y positions of the sample with respect to the electron beam to a signal detection system or an image processing system described later in advance, the signals indicating the rotation position and the X and Y positions of the sample obtained at the time of inspection are standardized. Can also be planned. Further, the sample chuck mechanism provided on the holder is adapted to apply a voltage for chucking the sample to the electrodes of the electrostatic chuck, and to provide three points on the outer peripheral portion of the sample (preferably equally spaced in the circumferential direction). (Located between them). The sample chuck mechanism has two fixed positioning pins and one pressing clamp pin. The clamp pin is capable of realizing automatic chucking and automatic release, and constitutes a conductive portion for voltage application.

  In this embodiment, the table moving in the left-right direction in FIG. 2 is an X table, and the table moving in the vertical direction is a Y table. The table to be moved may be an X table.

<Loader>
The loader 60 includes a robotic first transfer unit 61 disposed in the housing 22 of the mini-environment device 20 and a robotic second transfer unit 63 disposed in the second loading chamber 42. Have.

The first transport unit 61 has a multi-articulated arm 612 that is rotatable about the axis O ₁ -O ₁ with respect to the drive unit 611. Although any structure can be used as the multi-joint arm, this embodiment has three portions that are rotatably attached to each other. One portion of the arm 612 of the first transport unit 61, that is, the first portion closest to the driving unit 611, is a shaft rotatable by a driving mechanism (not shown) having a known structure provided in the driving unit 611. 613. The arm 612 is rotatable about the axis O ₁ -O ₁ by the shaft 613, and is generally expandable and contractible in the radial direction with respect to the axis O ₁ -O ₁ by relative rotation between the parts. A gripping device 616 for gripping a sample such as a mechanical chuck or an electrostatic chuck having a known structure is provided at the distal end of the third portion of the arm 612 farthest from the shaft 613. The driving unit 611 is vertically movable by a lifting mechanism 615 having a known structure.

  In the first transfer unit 61, the arm 612 extends in one of the directions M1 or M2 of the two cassettes c held by the cassette holder 10, and the arm accommodates the sample accommodated in the cassette c. Or take it out by holding it with a chuck (not shown) attached to the tip of the arm. Thereafter, the arm contracts (as shown in FIG. 2), rotates to a position where the arm can extend in the direction M3 of the pre-aligner 25, and stops at that position. Then, the arm 612 is extended again, and the sample held by the arm 612 is placed on the pre-aligner 25. After receiving the sample from the pre-aligner 25 in the opposite manner, the arm 612 further rotates and stops at a position where the arm 612 can extend toward the second loading chamber 41 (direction M4), and the sample in the second loading chamber 41 is stopped. The sample is delivered to the rack 47. When the sample is mechanically gripped, the peripheral portion of the sample (a range of about 5 mm from the peripheral edge) is gripped. This is because a device (circuit wiring) is formed on the entire surface except for the peripheral portion of the sample, and gripping this portion causes breakage of the device and generation of defects.

  The second transport unit 63 has basically the same structure as the first transport unit 61, and differs only in that the sample is transported between the sample rack 47 and the mounting surface of the stage device 50. Therefore, detailed description is omitted.

  In the loader 60, the first and second transfer units 61 and 63 substantially transfer the sample from the cassette held in the cassette holder 10 to the stage device 50 disposed in the working chamber 31 and vice versa. It is performed while keeping the horizontal state, and the arm of the transfer unit moves up and down simply by removing the sample from the cassette and inserting it into it, placing the sample on the sample rack and removing it from there, and Is placed only on the stage device 50 and taken out therefrom. Therefore, a large sample, for example, a sample having a diameter of 30 cm or 45 cm can be moved smoothly.

<Transport of sample>
Next, the transfer of the sample from the cassette c supported by the cassette holder 10 to the stage device 50 disposed in the working chamber 31 will be described step by step.

  As described above, the cassette holder 10 has a structure suitable for manually setting a cassette, and a structure suitable for automatically setting a cassette. In this embodiment, when the cassette c is set on the elevating table 11 of the cassette holder 10, the elevating table 11 is lowered by the elevating mechanism 12, and the cassette c is aligned with the entrance 225.

  When the cassette is aligned with the entrance 225, a cover (not shown) provided on the cassette c is opened, and a cylindrical cover is arranged between the cassette c and the entrance 225 of the mini-environment. c and the mini-environment space 21 are shielded from the outside. Since these structures are publicly known, detailed description of the structure and operation is omitted. When a shutter device for opening and closing the entrance 225 is provided on the mini-environment device 20 side, the shutter device operates to open the entrance 225.

  On the other hand, the arm 612 of the first transport unit 61 is stopped in a state facing either the direction M1 or M2 (the direction of M2 in this description). Receives one of the samples contained in. Note that the vertical position adjustment between the arm 612 and the sample to be taken out of the cassette c is performed by the vertical movement of the drive unit 611 and the arm 612 of the first transport unit 61 in this embodiment. It may be performed by vertically moving the elevating table 11, or both.

When the reception of the sample by the arm 612 is completed, the arm 612 contracts and operates the shutter device to close the entrance (if there is a shutter device), and then the arm 612 rotates about the axis O ₁ -O _1. It is in a state where it can be extended in the direction M3. Then, the arm 612 is extended, and the sample placed on the tip or held by the chuck is placed on the pre-aligner 25, and the pre-aligner 25 changes the direction of rotation of the sample (the direction around the central axis perpendicular to the sample surface). Position within a predetermined range. When the positioning is completed, the first transport unit 61 receives the sample from the pre-aligner 25 at the tip of the arm 612, and then contracts the arm 612 so that the arm 612 can be extended in the direction M4. Then, the door 272 of the shutter device 27 moves to open the entrances 226 and 436, and the arm 612 is extended to place the sample on the upper or lower side of the sample rack 47 in the first loading chamber 41. Before the shutter device 27 is opened and the sample is delivered to the sample rack 47 as described above, the opening 435 formed in the partition wall 434 is closed in an airtight state by the door 461 of the shutter device 46.

  In the process of transporting the sample by the first transport unit 61, clean air flows from the gas supply unit 231 provided on the housing 22 of the mini-environment device 20 in a laminar flow (as a down flow). Prevents dust from adhering to the upper surface of the sample. Part of the air around the transfer unit 61 (in this embodiment, air that is mainly contaminated with about 20% of the air supplied from the supply unit) is sucked from the suction duct 241 of the discharge device 24 and discharged to the outside of the housing. . The remaining air is collected through a collection duct 232 provided at the bottom of the housing 22 and returned to the gas supply unit 231 again.

  When a sample is placed on the sample rack 47 in the first loading chamber 41 of the loader housing 40 by the first transport unit 61, the shutter device 27 closes and the inside of the loading chamber 41 is sealed. Then, after the first loading chamber 41 is filled with an inert gas and the air is expelled, the inert gas is also discharged, and the inside of the loading chamber 41 is evacuated. The vacuum atmosphere of the first loading chamber 41 may be a low degree of vacuum. When a certain degree of vacuum in the loading chamber 41 is obtained, the shutter device 46 is operated to open the entrance 435 sealed by the door 461, and the arm 632 of the second transfer unit 63 is extended, and the sample is held by the gripping device at the tip. A single sample is received from the rack 47 (placed on the tip or gripped by a chuck attached to the tip). When the reception of the sample is completed, the arm 632 contracts, the shutter device 46 operates again, and the entrance 435 is closed by the door 461. Note that before the shutter device 46 is opened, the arm 632 is in a posture in which it can be extended in the direction N1 of the sample rack 47 in advance. In addition, as described above, the doors 452 of the shutter device 45 close the entrances 437 and 325 before the shutter device 46 opens, so that the communication between the second loading chamber 42 and the working chamber 31 is blocked in an airtight state. The inside of the second loading chamber 42 is evacuated.

When the shutter device 46 closes the entrance 435, the inside of the second loading chamber 42 is evacuated again, and the inside of the second loading chamber 41 is evacuated to a higher degree of vacuum than in the first loading chamber 41. Meanwhile, the arm 632 of the second transfer unit 63 is rotated to a position where the arm 632 can extend toward the stage device 50 in the working chamber 31. Meanwhile the stage device 50 in the working chamber 31, Y table 52, X-axis center line X ₀ -X ₀ of the X table 53 passes through the rotation axis O ₂ -O ₂ of the second transfer unit 63 X ₁ - It moves upward in FIG. 2 to a position almost coincident with X _1, and the X table 53 moves to a position approaching the leftmost position in FIG. 2 and stands by in this state. When the second loading chamber 42 becomes substantially the same as the vacuum state of the working chamber 31, the door 452 of the shutter device 45 moves to open the entrances 437 and 325, and the arm 632 extends so that the tip of the arm 632 holding the sample is working. It approaches the stage device 50 in the chamber 31. Then, the sample is mounted on the mounting surface 551 of the stage device 50. When the mounting of the sample is completed, the arm 632 contracts, and the shutter device 45 closes the entrances 437, 325.

  In the above, the operation up to the transfer of the sample in the cassette c to the stage device 50 has been described. To return the sample placed on the stage device 50 and processed to the stage c from the stage device 50 into the cassette c, Performs the reverse operation. In addition, since a plurality of samples are placed on the sample rack 47, while the sample is transferred between the sample rack 47 and the stage device 50 by the second transfer unit 63, the first transfer unit 61 The sample can be transported between the cassette c and the sample rack 47, and the inspection process can be performed efficiently.

  More specifically, when the sample rack 47 contains the already processed sample A and the unprocessed sample B, (1) first, the unprocessed sample B is moved to the stage device 50, and the processing is started. 2) During this processing, the processed sample A is moved from the stage device 50 to the sample rack 47 by the arm 632, and the unprocessed sample C is extracted from the sample rack 47 by the arm 632 and positioned by the pre-aligner 25. It moves to the sample rack 47 of the loading chamber 41. In this manner, in the sample rack 47, the processed sample A can be replaced with the unprocessed sample C while the sample B is being processed.

  Further, depending on how to use such a device for performing inspection and evaluation, a plurality of stage devices 50 are arranged in parallel, and a plurality of samples are moved from one sample rack 47 to each device. They can be processed simultaneously.

According to the above embodiment, the following effects can be obtained.
(A) An entire configuration of an inspection apparatus of a projection type using an electron beam is obtained, and an inspection target can be processed with high throughput.
(B) Inspection of the inspection target while monitoring dust in the mini-environment space by monitoring the dust in the mini-environment space by providing a sensor for observing the cleanliness by flowing a clean gas to the inspection target to prevent adhesion of the dust. Can be.
(C) Since the loading chamber and the working chamber are integrally supported via the vibration preventing device, it is possible to supply and inspect the inspection target to the stage device 50 without being affected by the external environment.

<Electronic optical device>
FIG. 3 is a diagram illustrating a configuration of the electron optical device 70. FIG. 4 is a diagram for explaining a beam path in the electron optical device 70. The inspection target (sample) of the electron optical device 70 is the sample W. The sample W is a silicon wafer, a glass mask, a semiconductor substrate, a semiconductor pattern substrate, a substrate having a metal film, or the like. The electron beam inspection apparatus according to the present embodiment detects the presence of foreign matter on the surface of the sample W composed of these substrates. The foreign substance is an insulator, a conductor, a semiconductor material, a composite thereof, or the like. The types of foreign matter include particles, cleaning residue (organic matter), and reaction products on the surface.

  As shown in FIGS. 3 and 4, the electron optical device 70 includes a primary optical system 72 that generates an electron beam and a secondary optical system that forms an enlarged image of secondary emission electrons or mirror electrons from the sample W. 74, a detector 761 for detecting the electrons, and an image processing unit 763 for processing a signal from the detector 761.

  The primary optical system 72 generates an electron beam and irradiates the electron beam toward the sample W. The primary optical system 72 has an electron gun 721, lenses 722 and 725, apertures 723 and 724, an E × B filter 726, lenses 727, 729 and 730, and an aperture 728. The electron gun 721 has a laser light source 7211 and a light emitting surface cathode 7212, and an electron beam is generated by the electron gun 721. The lenses 722 and 725 and the apertures 723 and 724 shape the electron beam and control the direction of the electron beam. Then, in the E × B filter 726, the electron beam is affected by Lorentz force due to a magnetic field and an electric field. The electron beam enters the E × B filter 726 from an oblique direction, is deflected vertically downward, and travels toward the sample W. The lenses 727, 729, and 730 control the direction of the electron beam and perform appropriate deceleration to adjust the landing energy LE.

  The primary optical system 72 irradiates the sample W with an electron beam. The primary optical system 72 irradiates both the precharged charging electron beam and the imaging electron beam. According to the experimental results, the difference between the landing energy LE1 of the precharge and the landing energy LE2 of the imaging electron beam is preferably 5 to 20 eV.

  In this regard, it is assumed that when there is a potential difference between the foreign matter on the surface 21 of the sample W and the surroundings, the landing energy LE1 of the precharge is applied to the negatively charged region. The charge-up voltage differs depending on the value of LE1. This is because the relative ratio between LE1 and LE2 changes (LE2 is the landing energy of the imaging electron beam as described above). When LE1 is large, the charge-up voltage becomes high, thereby forming a reflection point at a position above the foreign matter (a position closer to the detector 761). The trajectory and transmittance of mirror electrons change according to the position of the reflection point. Therefore, the optimum charge-up voltage condition is determined according to the reflection point. On the other hand, if LE1 is too low, the efficiency of mirror electron formation decreases. The difference between LE1 and LE2 is desirably 5 to 20 eV. The value of LE1 is preferably 0 to 40 [eV], and more preferably 5 to 20 [eV].

  By adjusting the conditions of the electric field and the magnetic field of the E × B filter 726, the angle of the primary electron beam can be determined. For example, the condition of the E × B filter 726 can be set so that the primary system irradiation electron beam and the secondary system electron beam enter the sample W almost perpendicularly. In order to further increase the sensitivity, for example, it is effective to tilt the incident angle of the primary electron beam with respect to the sample W. A suitable inclination angle is 0.05 to 10 degrees, preferably about 0.1 to 3 degrees.

  In this way, by irradiating the foreign matter with the electron beam at a predetermined angle θ, the signal from the foreign matter can be strengthened. Thereby, a condition can be formed in which the trajectory of the mirror electrons does not deviate from the center of the secondary system optical axis, and therefore, the transmittance of the mirror electrons can be increased. Therefore, when the foreign matter is charged up to guide the mirror electrons, the inclined electron beam is very advantageously used.

  The sample W is on the stage device 50, and there is a foreign matter on the sample W. The primary optical system 72 irradiates the surface 21 of the sample W with an electron beam at a landing energy LE-5 to -10 [eV]. The foreign matter is charged up, and the incident electrons of the primary optical system 72 are repelled without contacting the foreign matter. As a result, the mirror electrons are guided to the detector 761 by the secondary optical system 74. At this time, the secondary emission electrons are emitted from the surface 21 of the sample W in a direction spreading. Therefore, the transmittance of secondary emission electrons is a low value, for example, about 0.5 to 4.0%. On the other hand, since the direction of the mirror electrons is not scattered, the mirror electrons can achieve a high transmittance of almost 100%. Mirror electrons are formed by foreign substances. Therefore, only a signal of a foreign substance can generate high luminance (a state in which the number of electrons is large). The difference / proportion of the luminance from the surrounding secondary emission electrons increases, and a high contrast can be obtained.

  As described above, the image of the mirror electron is enlarged at a magnification larger than the optical magnification. Magnification ranges from 5 to 50 times. Under typical conditions, the magnification is often 20 to 30 times. At this time, the foreign matter can be detected even if the pixel size is three times or more the foreign matter size. Therefore, high speed and high throughput can be realized.

  For example, when the size of the foreign matter is 20 [nm] in diameter, the pixel size may be 60 [nm], 100 [nm], 500 [nm], or the like. As in this example, it is possible to image and inspect a foreign substance using a pixel size three times or more the size of the foreign substance. This is a remarkably superior feature for higher throughput as compared with the SEM method or the like.

  The secondary optical system 74 is means for guiding the electrons reflected from the sample W to the detector 761. The secondary optical system 74 has lenses 740 and 743, an NA aperture 742, an aligner 744, and a detector 761. The electrons are reflected from the sample W and pass through the objective lens 730, the lens 729, the aperture 728, the lens 727, and the E × B filter 726 again. Then, the electrons are guided to the secondary optical system 74. In the secondary optical system 74, electrons pass through the lens 740, the NA aperture 742, and the lens 743 to collect electrons. The electrons are arranged by an aligner 744 and detected by a detector 761.

  The NA aperture 742 has a role of defining the transmittance and aberration of the secondary system. The size and position of the NA aperture 742 are selected so that the difference between the signal from a foreign object (mirror electrons or the like) and the signal around (normal portion) increases. Alternatively, the size and position of NA aperture 742 are selected such that the ratio of the signal from the foreign object to the surrounding signal is increased. Thereby, S / N can be increased.

  For example, it is assumed that the NA aperture 742 can be selected in the range of φ50 to φ3000 [μm]. It is assumed that the detected electrons include mirror electrons and secondary emission electrons. In such a situation, it is advantageous to select an aperture size in order to improve the S / N of the mirror electronic image. In this case, it is preferable to select the size of the NA aperture 742 so as to reduce the transmittance of the secondary emission electrons and maintain the transmittance of the mirror electrons.

  For example, when the incident angle of the primary electron beam is 3 °, the reflection angle of the mirror electrons is approximately 3 °. In this case, it is preferable to select the size of the NA aperture 742 such that the trajectory of the mirror electrons can pass. For example, a suitable size is φ250 [μm]. Since the aperture is limited to the NA aperture (diameter φ250 [μm]), the transmittance of the secondary emission electrons decreases. Therefore, it is possible to improve the S / N of the mirror electronic image. For example, when the aperture diameter is changed from φ2000 to φ250 [μm], the background gradation (noise level) can be reduced to 以下 or less.

  The foreign matter may be made of any kind of material, for example, a semiconductor, an insulator, a metal, or the like, or a mixture of them. Since a natural oxide film or the like is formed on the surface of the foreign matter, the foreign matter is covered with the insulating material. Therefore, even if the foreign material is a metal, charge-up occurs in the oxide film. This charge-up is suitably used in this example.

  The detector 761 is a unit for detecting electrons guided by the secondary optical system 74. The detector 761 includes a two-dimensional sensor 7611. The two-dimensional sensor 7611 has a plurality of pixels arranged in a two-dimensional direction.

  As the two-dimensional sensor 7611, an EB (Electron Bombardment) semiconductor sensor can be used. For example, an EB-CMOS sensor may be applied to the two-dimensional sensor 7611. An EB-CMOS sensor can direct an electron beam (secondary beam) directly into it. Therefore, it is possible to obtain high MTF (Modulation Transfer Function) and contrast without deterioration in resolution due to the photoelectric conversion mechanism or the light transmission mechanism. Conventionally, detection of small foreign matter has been unstable. On the other hand, when EB-CMOS is used, it is possible to increase the S / N of a weak signal of a small foreign substance. Therefore, higher sensitivity can be obtained. The improvement in S / N reaches 1.2 to 2 times. Note that an EB-CCD sensor or an EB-TDI sensor may be used as the two-dimensional sensor.

  The two-dimensional sensor 7611 may be a charge coupled device (CCD) or a time delay integration (TDI) -CCD. These are sensors that perform signal detection after converting electrons into light. Therefore, means such as photoelectric conversion is required. Thus, electrons are converted to light using photoelectric conversion or a scintillator. The image information of the light is transmitted to the TDI that detects the light. Thus, electrons are detected.

  Note that the number of pixels of the two-dimensional sensor 7611 can be 2 k × 2 k to 10 k × 10 k. Further, the data rate of the two-dimensional sensor 7611 can be set to 10 GPPS or less. Further, the pixel size of the two-dimensional sensor 7611 can be 1 to 15 μm.

  The image processing unit 763 performs image processing such as noise reduction processing, integration processing, and sub-pixel alignment on the secondary beam image obtained by the detector 761. The processing speed of the image processing unit 763 can be set to 10 GPPS or less.

  The electron optical device 70 will be further described. The sample W is set on a stage device 50 that can move in the x, y, z, and θ directions. High-precision alignment is performed by the stage device 50 and the optical microscope 871. Then, the projection optical system performs the foreign substance inspection and the pattern defect inspection of the sample W using the electron beam. Here, the potential of the surface 21 of the sample W is important. In order to measure the surface potential, a surface potential measuring device that can be measured in a vacuum is attached to the main chamber 160. This surface potential measuring device measures a two-dimensional surface potential distribution on the sample W. Focus control is performed in the secondary optical system 74 that forms an electronic image based on the measurement result. A focus map of the two-dimensional position of the sample W is manufactured based on the potential distribution. Using this map, the inspection is performed while changing and controlling the focus during the inspection. As a result, blurring and distortion of the image due to a change in the surface circle potential depending on the location can be reduced, and accurate and stable image acquisition and inspection can be performed.

  In the example shown in FIG. 4, the secondary optical system 74 is configured to be able to measure a detection current of electrons incident on the NA aperture 742, and is further configured so that the EB-CCD 745 can be installed at the position of the NA aperture 742. I have. Such a configuration is very advantageous and efficient. The NA aperture 742 and the EB-CCD 745 are installed on an integral holding member 746 having openings 747 and 748. The secondary optical system 74 includes a mechanism capable of independently absorbing the current of the NA aperture 742 and acquiring the image of the EB-CCD 745. To realize this mechanism, the NA aperture 742 and the EB-CCD 745 are installed on an X, Y stage 746 that operates in a vacuum. Therefore, position control and positioning of the NA aperture 742 and the EB-CCD 745 are possible. Further, since the stage 746 is provided with the openings 747 and 748, the mirror electrons and the secondary emission electrons can pass through the NA aperture 742 or the EB-CCD 745.

  The operation of the secondary optical system 74 having such a configuration will be described. First, the EB-CCD 745 detects the spot shape of the secondary electron beam and its center position. Then, voltage adjustment of the stig meter, the lenses 740 and 743, and the aligner 744 is performed so that the spot shape is circular and minimized. In this regard, conventionally, it has not been possible to directly adjust the spot shape and astigmatism at the position of the NA aperture 742. Such a direct adjustment is possible in the present embodiment, and high-precision correction of astigmatism is possible.

  Further, the center position of the beam spot can be easily detected. Therefore, the position of the NA aperture 742 can be adjusted so that the hole center of the NA aperture 742 is arranged at the beam spot position. In this regard, conventionally, the position of the NA aperture 742 could not be directly adjusted. In the present embodiment, it is possible to directly adjust the position of the NA aperture 742. This enables the NA aperture 742 to be positioned with high accuracy, reduces the aberration of the electronic image, and improves the uniformity. Then, the transmittance uniformity is improved, and an electronic image with high resolution and uniform gradation can be obtained.

  In the inspection of foreign matter, it is important to efficiently acquire a mirror signal from the foreign matter. The position of the NA aperture 742 is very important because it defines the signal transmittance and aberration. The secondary emission electrons are emitted from the surface 21 of the sample W in a wide angle range according to the cosine rule, and reach a wide area (for example, φ3 [mm]) uniformly at the NA position. Therefore, the secondary emission electrons are insensitive to the position of the NA aperture 742. On the other hand, in the case of mirror electrons, the angle of reflection on the surface 21 of the sample W is substantially equal to the angle of incidence of the primary electron beam. Therefore, the mirror electrons show a small spread and reach the NA aperture 742 with a small beam diameter. For example, the spread region of the mirror electrons is 1/20 or less of the spread region of the secondary emission electrons. Therefore, the mirror electrons are very sensitive to the position of the NA aperture 742. The spread region of the mirror electrons at the NA position is usually a region of φ10 to 100 [μm]. Therefore, it is very advantageous to determine the position where the mirror electron intensity is the highest and to arrange the center position of the NA aperture 742 at the determined position.

  In order to realize the installation of the NA aperture 742 at such an appropriate position, in a preferred embodiment, the NA aperture 742 is mounted in the x, y direction with an accuracy of about 1 [μm] in a vacuum of an electron column. Moved to The signal strength is measured while moving the NA aperture 742. Then, the position having the highest signal strength is obtained, and the center of the NA aperture 742 is set at the obtained coordinate position.

The EB-CCD 745 is very advantageously used for measuring the signal strength. Thereby, two-dimensional information of the beam can be obtained, and the number of electrons incident on the detector 761 can be obtained. Therefore, quantitative evaluation of the signal intensity becomes possible.
Alternatively, the aperture arrangement may be determined so that the position of the NA aperture 742 and the position of the detection surface of the detector 761 realize a conjugate relationship, and the lens 743 between the NA aperture 742 and the detector 761 May be set. This configuration is also very advantageous. As a result, an image of the beam at the position of the NA aperture 742 is formed on the detection surface of the detector 761. Therefore, the beam profile at the position of the NA aperture 742 can be observed using the detector 761.

  Further, the NA size (aperture diameter) of the NA aperture 742 is also important. As described above, since the signal area of the mirror electrons is small, the effective NA size is about 10 to 200 [μm]. Further, the NA size is preferably a size larger by +10 to 100 [%] with respect to the beam diameter.

  In this regard, an electron image is formed by mirror electrons and secondary emission electrons. By setting the aperture size, the ratio of mirror electrons can be further increased. Thereby, the contrast of the mirror electrons can be increased, that is, the contrast of the foreign matter can be increased.

  More specifically, when the aperture of the aperture is reduced, the secondary emission electrons decrease in inverse proportion to the aperture area. Therefore, the gradation of the normal part becomes small. However, the mirror signal does not change, and the gradation of the foreign matter does not change. Therefore, the contrast of the foreign matter can be increased by an amount corresponding to the reduction of the surrounding gradation, and a higher S / N can be obtained.

  An aperture or the like may be configured so that the position of the aperture can be adjusted not only in the x and y directions but also in the z axis direction. This configuration is also advantageous. The aperture is suitably installed at a position where the mirror electrons are most narrowed. This makes it possible to reduce the aberration of the mirror electrons and the secondary emission electrons very effectively. Therefore, it is possible to obtain a higher S / N.

<Electronic image tracking method>
The electron optical device 70 will be further described. As shown in FIG. 3, the primary optical system 72 includes a first high-pressure reference tube 701 provided along a primary beam path so as to surround the primary beam path. In the primary optical system 72, the emission current can be 10 μA to 10 mA, the transmittance can be 20 to 50%, the spot size can be φ1 to φ100 μm, and the size of the irradiation area The (illumination field size) can be φ10 to φ1000 μm, and the magnification of the optical system can be 1/1 to 1/10.

  A high-speed deflector 749 is provided in the path of the secondary beam in the secondary optical system 74. Specifically, the high-speed deflector 749 is provided closer to the detector 761 than the NA aperture 742. The high-speed deflector 749 includes a multipole (12 poles in the present embodiment), generates an octupole field and a hexapole field, and deflects the secondary beam in an arbitrary direction. The deflection direction (deflection amount) is controlled by the control device 2 functioning as the deflection control device 90. The configuration of the high-speed deflector 749 will be further described later. The multipole used for the high-speed deflector 749 may be an 8-pole, 4-pole, or other multipole. Also, the multipole may generate only a hexapole field or may generate only an octupole field.

  In the secondary optical system 74, the magnification can be 10 to 10,000 times, the size of the sample captured by one pixel of the two-dimensional sensor 7611 can be 3 to 100 nm (3 to 100 nm Px), and the NA aperture is 742 can have a transmittance of 10 to 50%, and the defect sensitivity can be 1 to 50 nm.

  The control device 2 functions as a deflection control device that controls the deflection direction of the high-speed deflector 749 as described above, and also controls an electron-optical control device that controls other operations of the electron optical device 70 and a stage that controls the stage device 50. It also functions as a control device, a transport control device that controls a configuration for transporting the sample W, an imaging control device that controls imaging of the two-dimensional sensor 7611, and the like. In particular, in the present embodiment, the sample W is moved at a constant speed by the stage device 50 during the inspection, but the control device 2 controls the stage device 50 to control the movement of the sample W. In FIG. 3, a set of the fixed table 51, the Y table 52, the X table 53, and the rotary table 54 in FIGS. 1 and 2 is denoted by reference numeral 56.

  FIG. 5A is a diagram illustrating the operation of the high-speed deflector 749 that deflects the secondary beam so that the secondary beam follows the movement of the sample W. As shown in FIG. 5A, when the sample W is continuously moving in the right direction, the high-speed deflector 749 outputs the secondary beam from the position A1 on the sample W to the two-dimensional sensor 7611. While the secondary beam is deflected so as to form a secondary beam image, while the sample W moves to the right, the secondary beam image of the portion of the sample W at the position A1 is formed with the movement. The deflection direction of the secondary beam is changed so that an image is always formed on the two-dimensional sensor 7611. That is, the high-speed deflector 749 moves the absolute position in the space where the secondary beam image is formed on the two-dimensional sensor 7611, following the movement of the sample W. Note that the deflection cycle of the high-speed deflector 749 can be set to 100 kHz to 100 MHz.

  By such a change (following) of the deflection direction of the secondary beam, the two-dimensional sensor 7611 always receives the first time until the portion of the sample W at the position A1 reaches the position of the position A2 by movement. The secondary beam from the portion of the sample W at the position A1 enters, and during this period (one cycle), the two-dimensional sensor 7611 captures a secondary beam image of the same region of the sample W. Become. When the portion of the sample W at the position A1 reaches the position A2, the high-speed deflector 749 returns the field of view to the position A1 again. Thereby, a secondary beam image of a new portion of the sample W can be captured. After the visual field of the two-dimensional sensor 7611 returns from the position A2 to the position A1, similarly, the deflection direction of the secondary beam is changed by the high-speed deflector 749 to follow the movement of the sample W, The visual field of the two-dimensional sensor 7611 moves from the position A1 to the position A2.

  As described above, the visual field of the two-dimensional sensor 7611 reciprocates between the position A1 and the position A2, and the primary beam must always be irradiated to the visual field. In order to realize this, as shown in FIG. 5B, the primary beam is irradiated onto the sample so that the irradiation region EF of the primary beam covers both the viewing region VF1 at the position A1 and the viewing region VF2 at the position A2. What is necessary is just to irradiate W, ie, the irradiation area | region EF should just have the magnitude | size for two visual field areas. In this case, the irradiation area EF of the primary beam can always be fixed at this position.

  Further, as shown in FIG. 5C, the irradiation region of the primary beam may be moved from the irradiation region EF1 at the position A1 to the irradiation region EF2 at the position A2 by following the movement of the sample W and the visual field region. At this time, the irradiation area of the primary beam can be changed by changing the deflection direction of the primary beam by the E × B filter 726.

  In the secondary optical system 74, a second high-pressure reference pipe 702, a third high-pressure reference pipe 703, and a fourth high-pressure reference pipe 704 are sequentially provided with a secondary beam path from the side closer to the sample W which is a sample. Along this path. The second high-pressure reference pipe 702 is provided between the sample W and the E × B filter 726 as a beam separator, and the third high-pressure reference pipe 703 is closer to the two-dimensional sensor 7611 than the E × B filter 726. And the fourth high-pressure reference pipe 704 is provided between the third high-pressure reference pipe 703 and the detector 761. The NA aperture 742 is provided inside the third high-pressure reference pipe 703, and the high-speed deflector 749 is provided inside the fourth high-pressure reference pipe 704.

  The first high-voltage reference pipe 701, the second high-pressure reference pipe 702, the third high-pressure reference pipe 703, and the fourth high-pressure reference pipe 704 have a first voltage V1, a second voltage V2, and a third voltage, respectively. A voltage V3 and a fourth voltage V4 are applied. In the embodiment, assuming that the detection voltages of the detector 761 are V5, these voltages have a relationship of V1 = V2 = V3, V3> V4, and V4 = V5. That is, in order to deflect the secondary beam at a high speed by the high-speed deflector 749, the voltage V4 applied to the fourth high-pressure reference tube 704 is made smaller than the third voltage V3 to reduce the electron energy of the secondary beam. ing. Here, the third voltage V3 is, for example, 40 kV, and the fourth voltage V4 is, for example, 5 kV.

As described above, the secondary beam is deflected by the high-speed deflector 749. If the electron energy of the secondary beam at that time is larger than, for example, 10 kV, it is necessary to increase the deflection voltage in the high-speed deflector 749. Is difficult to deflect at high speed. Therefore, the fourth high-pressure reference pipe 704 is provided separately from the third high-pressure reference pipe, the voltage applied to the fourth high-pressure reference pipe 704 is reduced to, for example, about 5 kV, and the light is incident on the high-speed deflector 749. It is necessary to reduce the electron energy of the secondary beam. On the other hand, such an abrupt change from the third voltage to the fourth voltage causes a curvature aberration in the secondary beam, resulting in an image of the secondary beam (secondary beam image) formed on the detector 761. Distortion occurs.

  Therefore, in the present embodiment, an intermediate electrode (relaxation electrode) 750 is provided between the third high-voltage reference pipe 703 and the fourth high-pressure reference pipe 704, and the third electrode V3 is applied to the intermediate electrode. An intermediate voltage that is larger and smaller than the fourth voltage V4 is applied. As a result, the occurrence of the above-described curvature aberration can be suppressed, and thus the distortion of the secondary beam image can be suppressed.

  FIG. 6 is a diagram showing a configuration of a combination unit of a high-speed deflector, an imaging lens, and an intermediate electrode. The intermediate electrode 750 is connected between a third high-voltage reference tube 703 to which a third voltage of, for example, 40 kV is applied and a fourth high-voltage reference tube 704 to which a fourth voltage of, for example, 5 kV is applied. Are arranged without contacting the high-voltage reference pipe 703 and the fourth high-pressure reference pipe 704, and an intermediate voltage of, for example, 10 kV to 13 kV is applied.

  The high-speed deflector 749 uses the 12-pole structure as described above in order to deflect the secondary beam with high accuracy. The twelve poles are arranged at equal angular intervals, and a voltage can be individually applied by the control device 2. The voltage accuracy of the high-speed deflector 749 is improved by using a power supply and an amplifier for high-speed deflection superimposed on the fourth voltage V4 by the fourth high-voltage reference pipe.

  The imaging lens 741 employs a double magnetic lens system. By reversing the magnetic flux directions of the upper coil 7411 and the lower coil 7412, the secondary beam image can be rotated. Further, the coils 7411 and 7412 for the magnetic field lens are of a two-wiring type, whereby the temperature can be stabilized with a constant power. Since an image is formed in a state where the electron energy is changed from the third voltage V3 by the third high-voltage reference tube 703 to the fourth voltage V4 by the fourth high-voltage reference tube 704, an imaging lens is formed near the potential change. 741, and an intermediate electrode (electrode for alleviating electric field) 750 for mitigating the influence of the lens effect due to the electric field change is disposed at the preceding stage. Thereby, the distortion of the secondary beam image due to a sudden potential change can be suppressed.

  The secondary beam image becomes larger as it approaches the detector 761 that performs enlarged imaging by the imaging lens 741. Therefore, in order to perform high-speed deflection at a position near the imaging lens 741 where the secondary beam image is small, a high-speed deflector 749 is installed near the imaging lens. That is, when the secondary beam image becomes large, the deflection voltage required to deflect the secondary beam becomes large, and the deflection sensitivity is reduced, so that high-speed deflection becomes difficult, the above-described distortion correction accuracy is reduced, and the Vibration correction accuracy also decreases. Therefore, it is desirable that the intermediate electrode 750, the imaging lens 741, and the high-speed deflector 749 are arranged as close as possible in this order to the traveling direction of the secondary beam, and it is desirable that the intermediate electrode 750, the imaging lens 741, and the high-speed deflector 749 be configured as a unit. .

  The high-speed deflector 749 performs not only the deflection for following the movement of the sample W but also the distortion correction of the secondary beam image as described above and the vibration correction to be described later. This is realized by individually applying a voltage to the poles.

  Returning to FIG. 3, the vibration correction will be described. As described above, the sample W is continuously moved at a constant speed by the stage device 50, and the high-speed deflector 749 changes the deflection direction of the secondary beam so that the visual field moves following the movement of the sample W. At this time, an unintended vibration may be given to the movement of the sample W by the stage device 50 at this time. As described above, during one cycle of the movement of the visual field region, the two-dimensional sensor 7611 always captures a secondary beam image of the same portion of the sample W, but when an unintended vibration is applied to the sample W, Contamination occurs in which a secondary beam from another part of the sample W is incident on each pixel of the two-dimensional sensor 7611.

  As described above, the stage device 50 moves the sample W held by the holder 55 in the X direction and the Y direction by operating a plurality of tables using the servomotor, the encoder, and various sensors (not shown). Positioning is performed with high accuracy in the Z direction (vertical direction in FIG. 1) and further around the axis perpendicular to the support surface of the sample (θ direction). As a configuration for this, a mirror 571 is fixed to the holder 55, and a laser beam is applied to the inner wall of the main housing 30 to irradiate the mirror 571 with a laser beam, and the laser reflected from the mirror 571 and returned is incident. 572 are provided.

  In the inspection apparatus 1 of the present embodiment, the vibration is corrected by using the mirror 571 fixed to the holder 55 and the laser interferometer 572 as the vibration detecting means. The unintended vibration of the sample W detected by the laser interferometer 572 is input to the control device 2. The controller 2 is instructed to change the direction of deflection of the secondary beam by the high-speed deflector 749 when the sample W moves without causing unintended vibration. The high-speed deflector 749 is controlled by determining the direction of deflection of the secondary beam by the high-speed deflector 749 in consideration of not only the movement but also the unintended vibration of the sample W detected by the laser interferometer 572. Note that the control device 2 does not have to be instructed to change the direction of deflection of the secondary beam by the high-speed deflector 749 when the sample W moves without causing unintended vibration. 2 detects the position of the sample W (the holder 55 holding the sample W) including the unintended vibration of the sample W detected by the laser interferometer 572, and based on this position, detects the secondary beam by the high-speed deflector 749. May be determined to control the high-speed deflector 749.

  As described above, in the inspection apparatus 1 including the electron optical device 70 of the present embodiment, while the sample W is moving, the secondary beam of the same portion of the sample W is synchronized with the movement of the sample W. A high-speed deflector 749 that deflects the secondary beam so as to be incident on the same part of the two-dimensional sensor 7611 is a distortion corrector that corrects the distortion of the secondary beam image, and corrects contamination due to unintended vibration of the sample W. Also, the two-dimensional sensor 7611 can obtain a highly accurate secondary beam image.

  Note that the first voltage V1, the second voltage V2, the third voltage V3, the fourth voltage V4, and the detection voltage V5 are not limited to the above examples, and for example, V1 <V2, V2 = V3, V3>. The relationship may be V4, V4 = V5, that is, the first voltage V1 may be smaller than the second voltage V2 and the third voltage V3. When the voltage V1 applied to the first high-pressure reference tube 701 in the primary optical system 72 is reduced, the risk of discharge in the first high-pressure reference tube 701 can be reduced. That is, the primary optical system has an aperture 723 in the first high-pressure reference tube 701, and the aperture 723 absorbs 50% or more of the emission from the electron gun 721, so that the leakage current amount is large and the leakage current is large. The fluctuation of the current amount is large. On the other hand, by reducing the first voltage V1 applied to the first high-voltage reference tube 701, the risk of discharge can be reduced or eliminated.

  Further, in the inspection device 1 described above, a voltage control device that adjusts the fourth voltage V4 applied to the fourth high-voltage reference pipe 704 may be provided to make the fourth voltage V4 variable. At this time, the fourth voltage V4 may be adjustable within a range of, for example, ± 1 kV. By adjusting the fourth voltage V4 in this manner, the electron energy (incident energy) of the secondary beam incident on the detector 761 can be adjusted. Thus, the gain of the two-dimensional sensor 7611 (that is, the luminance of the secondary beam image) can be adjusted.

<Re-inspection simulation by software>
Referring back to FIG. 3, as described above, the electron optical device 70 irradiates the sample W, which is the sample held by the stage device 50, with the primary beam, which is a surface beam, and thereby generates the secondary beam generated from the sample W. The beam is directed to detector 761. The detector 761 captures the secondary beam by a two-dimensional sensor (not shown), generates an image of a secondary beam image, and outputs the image to the image processing unit 763.

  The image processing unit 763, as an inspection processing device, applies an image processing filter (average (Mean) filter, Gaussian (Gaussian) filter, median filter, etc.) to the secondary beam image input from the detector 761. ), Image processing is performed, shading correction is performed, and inspection is performed by comparison processing such as cell-cell comparison, die-die comparison, and die-database comparison. Specifically, the image processing unit 763 detects a portion where the difference exceeds a predetermined threshold in the comparison process as a defect, and generates a defect image.

  The image processing unit 763 performs an inspection according to the set inspection condition parameters. The inspection condition parameters include a cell cycle in the case of cell-cell comparison, an allowable edge value in the case of die-die comparison, a threshold for detecting a defect, an image processing filter, a shading correction value, and a parameter of die-database comparison. And the classification information of the defect that the user does not want to detect. The classification information of the defect that is not desired to be detected is obtained as a result of performing classification by performing imaging with an SEM after inspection.

  By the way, in an inspection apparatus for inspecting a defect occurring in a sample, in order to surely detect a true defect and not to detect a non-defect part (pseudo defect), inspection conditions such as a detection threshold are set. Inspections must be repeated many times while changing to determine the optimal inspection conditions.

  However, there is a problem in that if the inspection is repeated, it takes time to optimize the inspection conditions. In addition, by repeating the inspection, problems such as accumulation of damage on the sample and contamination of the sample arise.

  Therefore, the inspection apparatus 1 of the present embodiment is provided with a simulation apparatus 200 in order to determine the inspection conditions with a small number of inspections while avoiding damage to the sample and contamination of the sample. The image processing unit 763 outputs the defect image and the unprocessed image (secondary beam image) used to generate the defect image to the simulation device 200.

  The simulation device 200 includes a simulation processing unit 201, an input unit 202, and a monitor 203. For example, a general-purpose computer including an input unit, a monitor, an arithmetic processing unit, a memory, a storage device, an input / output port, and the like. Composed of The simulation processing unit 201 is realized by the inspection result review program of the present embodiment being executed by the arithmetic processing unit. The inspection result review program may be provided to the simulation device 200 via a network, or may be provided to the simulation device 200 by reading out the search result review program stored in the storage medium. The search result review program provided in this way is stored in the storage device of the simulation device 200, read out therefrom, and executed to configure the simulation processing unit 201.

  The simulation processing unit 201 performs re-inspection simulation on the secondary beam image input from the inspection apparatus 100 while changing the inspection condition parameters, and determines an optimal inspection condition parameter. The inspection condition parameters changed by the simulation processing unit 201 for the re-inspection simulation include a cell cycle in the case of cell-cell comparison, an allowable edge value in the case of die-die comparison, a threshold for detecting defects, and image processing. The information includes a filter, a shading correction value, a die-database comparison parameter, classification information of a defect not to be detected, and the like.

  FIG. 7 is a flowchart showing the operation of the simulation apparatus 200. First, the electron optical device 70 performs an inspection, and the image processing unit 763 outputs an inspection result to the simulation device 200 (Step S331). At this time, the image processing unit 763 outputs to the simulation device 200 the inspection result, the unprocessed image (secondary beam image) used to obtain the inspection result, and the classification information of the defect not to be detected. In the simulation device 200, the simulation processing unit 201 reads the inspection result, generates a defect image, and displays it on the monitor 203 (step S332).

  Next, the simulation processing unit 201 changes the inspection condition, executes a re-inspection simulation (step S333), and outputs a re-inspection result obtained thereby (step S334). In the re-inspection simulation, similarly to the inspection in the electron optical device 70, a defect in the classification information of a defect not to be detected is not detected. The simulation processing unit 201 reads the re-inspection result obtained in step S334, generates a defect image, and outputs it to the monitor 203 (step S335).

  Next, by evaluating the defect image obtained by the re-inspection, it is determined whether the inspection condition is optimal (step S336). If the inspection condition is not optimal (NO in step S336), the process proceeds to step S333. Then, the inspection condition is changed and the re-inspection simulation is executed (step S333). As described above, the re-inspection simulation while changing the inspection condition parameters is repeated, and when the inspection condition becomes optimal (YES in step S336), the inspection condition adopted by the electro-optical device 70 becomes the optimal inspection condition. Is determined (step S337), and the process ends. The simulation processing unit 201 may determine whether the search condition is optimal based on an input from the input unit 202, for example.

  As described above, according to the present embodiment, after performing an actual inspection in the electron optical device 70, the inspection is performed by using the defect image and the unprocessed image output from the electron optical device 70 in the simulation device 200. Since the reinspection simulation is performed by the inspection result review software while changing the conditions, the inspection conditions can be optimized with a small number of inspections, and the time for optimizing the inspection conditions can be reduced. Further, since there is no need to repeat the actual inspection by the electron optical device 70, damage to the sample can be reduced, and contamination of the sample can be reduced.

The electron gun 721 in the inspection apparatus described above will be described in detail.
As shown in FIG. 3, the electron gun 721 has a laser light source 7211 and a light emitting surface cathode 7212. Although not shown, it is assumed that a bias voltage appropriate for electron emission is applied to the photocathode cathode 7212. The light emitting surface cathode 7212 functions as a photoelectric conversion surface that converts the laser light emitted from the laser light source 7211 into an electron beam. When the laser light is continuously irradiated on a certain portion of the light emitting surface cathode 7212, energy is concentrated on that portion and deteriorates in a short time. Further, since the irradiation efficiency of the light emitting surface cathode 7212 is not always uniform, it is conceivable that even if the light emitting surface cathode 7212 is uniformly irradiated with the laser beam, the electron beam density distribution becomes non-uniform.

  Therefore, in the following, the position on the light emitting surface cathode 7212 to be irradiated with the laser light is time-modulated to extend the life of the light emitting surface cathode 7212 and to make the electron beam uniform.

  FIG. 8 is a schematic block diagram showing a schematic configuration of the electron gun 721. The electron gun 721 has an optical deflector 7213, an electron beam deflector 7214, and a control unit 7215 in addition to the laser light source 7211 and the light emitting surface cathode 7212.

  The optical deflector 7213 deflects the laser light from the laser light source 7211. The deflection amount (or deflection direction) is time-modulated by the control unit 7215. More specifically, the optical deflector 7213 has an X-direction optical deflector 7213a and a Y-direction optical deflector 7213b. The X-direction light deflector 7213a deflects the laser light on a predetermined X plane (for example, a plane parallel to the plane of FIG. 8). The Y-direction light deflector 7213b deflects the laser light on a predetermined Y plane different from the X plane (for example, a plane orthogonal to the X plane and perpendicular to the plane of the plan view 8).

  The X-direction light deflector 7213a can be constituted by, for example, a galvanomirror shown in FIG. The galvanometer mirror includes a drive motor D and a mirror surface M rotated by the drive motor D. By controlling the drive motor D from the control unit 7215 in FIG. 8, the mirror surface M rotates about the axis of the drive motor D, and the laser light is deflected in the plane. The Y-direction optical deflector 7213b can also be constituted by a galvanomirror. Alternatively, the X-direction light deflector 7213a and the Y-direction light deflector 7213b may be configured by a polygon mirror or an AO (acousto-optic) deflector.

  By providing the optical deflector 7213, the laser light is dispersed and radiated to a wide position without being intensively radiated to a position of the light-emitting surface cathode 7212. That is, the position on the light emitting surface cathode 7212 irradiated with the laser light is time-modulated.

  The lightning surface cathode 7212 converts the laser light into an electron beam. More specifically, an electron beam is irradiated from the position on the lightning surface cathode 7212 where the laser light is irradiated. Therefore, where the electron beam is irradiated on the light emitting surface cathode 7212 differs depending on the time. Therefore, an electron beam deflector 7214 is provided so that a constant point is always irradiated with the electron beam.

  The electron beam deflector 7214 deflects the electron beam so that the irradiated electron beam from any position on the light emitting surface cathode 7212 reaches a predetermined point. Since the position on the light emitting surface cathode irradiated with the laser light is time-modulated, the amount of deflection (or the direction of deflection) by the electron beam deflector 7214 also needs to be time-modulated by the control unit 7215. The predetermined point to which the electron beam travels may be, for example, a point to which the electron beam emitted from the center of the light emitting surface cathode 7212 travels.

  The electron beam deflector 7214 has an X-direction electron beam deflector including a positive X electrode 7214a and a negative X electrode 7214b, and a Y-direction electron beam deflector including a positive Y electrode 7214c and a negative Y electrode 7214d.

  The positive X electrode 7214a and the negative X electrode 7214b are arranged so that an electron beam is deflected in the X direction by applying a voltage to them. The amount of deflection (deflection direction) can be controlled by the magnitude and sign of the voltage. Therefore, the X-direction electron beam deflector deflects the electron beam so that the deflection of the laser beam by the X-direction light deflector 7213a is canceled.

  Similarly, the positive Y electrode 7214c and the negative Y electrode 7214d are arranged so that an electron beam is deflected in the Y direction by applying a voltage to them. The amount of deflection (deflection direction) can be controlled by the magnitude and sign of the voltage. Therefore, the Y-direction electron beam deflector deflects the electron beam so that the deflection of the laser beam by the Y-direction light deflector 7213b is canceled.

  The control unit 7215 includes a drive signal generator (not shown) that generates a drive signal for controlling the drive of the X-direction light deflector 7213a and the Y-direction light deflector 7213b. Further, the control unit 7215 generates an X-direction amplifier (not shown) that generates a voltage applied to the positive X electrode 7214a and the negative X electrode 7214b, and generates a voltage that is applied to the positive Y electrode 7214c and the negative Y electrode 7214d. And a Y-direction amplifier (not shown).

  Then, the control unit 7215 controls the amount of light deflection by the optical deflector 7213 and the amount of electron beam deflection by the electron beam deflector 7214 in synchronization with each other so that the electron beam is irradiated to a predetermined point.

  More specifically, the control unit 7215 synchronizes the amount of deflection by which the X-direction optical deflector 7213a deflects the laser beam in the X direction and the amount of deflection by which the X-direction electron beam deflector deflects the electron beam in the X direction. And control. Also, the control unit 7215 controls the amount of deflection by which the Y-direction optical deflector 7213b deflects the laser beam in the Y direction and the amount of deflection by which the Y-direction electron beam deflector deflects the electron beam in the Y direction. .

  By providing such a control unit 7215, the position of the laser beam applied to the light emitting surface cathode 7212 can be modulated, and the electron beam from the light emitting surface cathode 7212 can be directed to a predetermined point.

  In order to perform control in synchronization, the control unit 7215 controls the X-direction optical deflector 7213a based on a reference signal of a certain frequency and controls the X-direction electron beam deflector based on the reference signal. Thus, both can be controlled synchronously. Similarly, the control unit 7215 controls the Y-direction optical deflector 7213b based on a reference signal of a certain frequency, and controls the Y-direction electron beam deflector based on the same reference signal, thereby controlling the two in synchronization. it can.

  When the X-direction optical deflector 7213a outputs a signal indicating the amount of deflection (deflection direction), the control unit 7215 may control the X-direction electron beam deflector based on the signal. Thereby, the control unit 7215 can control the X-direction optical deflector 7213a and the X-direction electron beam deflector synchronously, the X-direction optical deflector 7213a deflects the laser light by mechanical operation, and the X-direction electron beam deflector Even when the electron beam is electrically deflected, it is possible to suppress the occurrence of a phase shift and a response time difference between the operations.

  When the X-direction optical deflector 7213a is the galvanomirror shown in FIG. 9, the signal indicating the amount of deflection can be a signal from a detector that detects the position and angle of the mirror surface M. This is because the position and angle of the mirror surface M correspond to the amount of deflection. This detector is attached to the galvanometer mirror. The same applies to the Y direction.

  As described above, in the present embodiment, the laser light from the laser light source 7211 is deflected, and the position of the light emitting surface cathode 7212 where the laser light is irradiated is dispersed. Therefore, the electron beam is irradiated from a wide range on the light emitting surface cathode 7212. Therefore, even if the irradiation efficiency of the light emitting surface cathode 7212 is not uniform, a uniform electron beam can be generated, and as a result, the inspection can be performed with high accuracy. In addition, since the position on the light emitting surface cathode 7212 where the laser light is irradiated is dispersed, the life of the light emitting surface cathode 7212 is extended.

  1: inspection device, 2: control device, 2a: first angle deviation detection unit, 2b: second angle deviation detection unit, 2c: third angle deviation detection unit, 2d: alignment control unit, 30: main housing, 50: Stage device, 55: holder, 571: mirror, 572: laser interferometer, 70: electron optical device, 761: detector, 7611: two-dimensional sensor, 763: image processing unit, 72: primary optical system, 74: 2 Next optical system, 7211: laser light source, 7212: light emitting surface cathode, 7213: optical deflector, 7214: electron beam deflector, 7215: control unit, 722: lens, 701: first high-pressure reference tube, 702: second 703: third high-pressure reference pipe, 704: fourth high-pressure reference pipe, 749: high-speed deflector, 742: NA aperture, 726: EXB filter, 750: intermediate electrode, 90: Direction control device

Claims (6)

A light source for emitting light,
An optical deflector that deflects light from the light source, wherein the amount of deflection is time-modulated, and
A photoelectric conversion surface that converts the deflected light into an electron beam,
An electron beam deflector that deflects the electron beam from the photoelectric conversion surface toward a predetermined point,
The optical deflector,
A first light modulator that deflects the light in a first direction;
A second light modulator that deflects the light in a second direction substantially orthogonal to the first direction,
The electron beam deflector,
A first electron beam deflector for deflecting the electron beam in the first direction;
A second electron beam deflector for deflecting the electron beam in the second direction,
The first electron beam deflector deflects the electron beam in the first direction so that light deflection by the first light modulator is canceled,
The electron gun, wherein the second electron beam deflector deflects the electron beam in the second direction so that light deflection by the second light modulator is canceled. While controlling the amount of deflection by the first optical modulator and the amount of deflection by the first electron beam deflector in synchronization,
2. The electron gun according to claim 1, further comprising a control unit that controls the amount of deflection by the second light modulator and the amount of deflection by the second electron beam deflector in synchronization. The control unit includes:
Based on a first reference signal of a predetermined frequency, synchronously controlling both the amount of deflection by the first optical modulator and the amount of deflection by the first electron beam deflector;
3. The electron gun according to claim 2, wherein both an amount of deflection by the second optical modulator and an amount of deflection by the second electron beam deflector are synchronously controlled based on a second reference signal having a predetermined frequency. . The control unit includes:
Receiving a signal corresponding to the deflection amount from the first optical modulator, controlling a deflection amount of the first electron beam deflector based on the signal,
3. The electron gun according to claim 2, wherein a signal corresponding to the amount of deflection is received from the second optical modulator, and the amount of deflection of the second electron beam deflector is controlled based on the signal. .   The electron gun according to claim 1, wherein the optical deflector includes one of a galvanomirror, a polygon mirror, and an AO deflector. A stage device on which the sample is placed and continuously moved,
An electron gun according to any one of claims 1 to 4, which emits an electron beam;
A primary optical system that guides the electron beam from the electron gun as a primary beam to the sample on the stage device,
A detector including a two-dimensional sensor that generates an image of a secondary beam generated from the sample by irradiating the sample with the primary beam,
An inspection apparatus comprising: a secondary optical system that guides the secondary beam to the two-dimensional sensor.