JP6581783B2 - Electron beam inspection equipment - Google Patents

Description

  The present invention relates to an electron that inspects a defect or the like of a pattern formed on a surface of an inspection object using an electron optical device that captures secondary charged particles that change in accordance with the property of the surface of the inspection object and forms image data. The present invention relates to a line inspection apparatus.

  In the process chamber of an electron beam inspection apparatus that inspects the sample surface using an electron beam, particles generated by stage driving or electron beam irradiation accumulate in the chamber, adhere to the sample surface during transport or inspection, and then The process could be affected. Therefore, conventionally, the process chamber is periodically opened to the atmosphere, and the inside of the chamber is wiped to perform cleaning to remove particles accumulated on the inner wall of the chamber and the stage.

Japanese Unexamined Patent Publication No. 3-76214

  The conventional method of performing the wiping operation in the chamber by opening the process chamber to the atmosphere has a problem that the operation takes time. Although not related to cleaning of the process chamber, an apparatus described in Patent Document 1 has been known as an apparatus related to sample contamination prevention. The apparatus described in Patent Document 1 keeps the sample clean by blowing up dust attached to the sample by blowing gas onto the sample on the transport mechanism.

  However, since particles generated in the process chamber may adhere to the inner wall or stage of the chamber due to static electricity, it is expected that it is difficult to remove the particles properly even if gas is blown.

  In view of the above background, an object of the present invention is to provide an electron beam inspection apparatus capable of removing particles in a process chamber without performing a wiping operation by opening to the atmosphere.

  An electron beam inspection apparatus according to the present invention is an electron beam inspection apparatus that inspects a sample surface using an electron beam, and an ionized gas generator that generates ionized gas, and a gas generated by the ionized gas generator. An introduction pipe to be introduced into the process chamber; an on-off valve provided on the introduction pipe; a vacuum pump for evacuating the process chamber; and a control unit for controlling the on-off valve and the vacuum pump, The control unit performs control to evacuate the process chamber after purging the ionized gas into the process chamber. Here, clean dry air or nitrogen may be used as the gas.

  With this configuration, particles in the process chamber can be removed by neutralizing particles generated by stage driving, electron beam irradiation, or the like with ionized gas, and then performing vacuum evacuation. In addition, since the cleaning can be performed without exposing the process chamber to the atmosphere, the maintenance time can be greatly shortened.

  In the electron beam inspection apparatus of the present invention, the control unit may repeat the purge and the evacuation in a viscous flow region.

  The viscous flow region is a state in which the pressure is high and the collision between molecules is dominant. When Knudsen number (index indicating viscous flow / molecular flow) is K, for example, the state is K <0.01. . In the molecular flow region, the ionized gas introduced into the process chamber diverges at the molecular level, whereas in the viscous flow region, the ionized gas can flow. By repeating the purge and evacuation in the viscous flow region, the charged particles can be appropriately neutralized and removed.

  In the electron beam inspection apparatus of the present invention, ports for introducing the ionized gas and evacuating may be provided at a plurality of locations. Here, the plurality of ports may be arranged so that the ionized gas does not accumulate in the process chamber, or may be arranged so that the ionized gas flows along the inner wall of the process chamber.

  By using a plurality of ports, purging and evacuation can be performed efficiently. In addition, particles in the process chamber can be efficiently removed by designing the arrangement of the ports so that the accumulation of ionized gas is eliminated or the ionized gas flows along the inner wall.

  In the electron beam inspection apparatus of the present invention, the control unit may control the flow rate of the ionized gas by controlling the opening degree of the open / close valve.

  By controlling the flow rate at the time of purging the ionized gas, for example, by rolling up the particles, the particles can be efficiently removed.

  In the electron beam inspection apparatus of the present invention, the ionized gas generator generates a positively charged ionized gas and a negatively charged ionized gas, and the control unit generates a positively charged ionized gas and a negatively charged ionized gas. Gas may be alternately introduced into the process chamber.

  By using a positively charged ionized gas and a negatively charged ionized gas in this way, the charging of the particles in the process chamber is neutralized regardless of whether the particles in the process chamber are positively or negatively charged. be able to.

  The cleaning device of the present invention is a device for cleaning a chamber, an ionized gas generator for generating ionized gas, an introduction pipe for introducing the gas generated by the ionized gas generator into the chamber, An opening / closing valve provided on the introduction pipe, a vacuum pump for evacuating the chamber, and a control unit for controlling the opening / closing valve and the vacuum pump, wherein the control unit is ionized in the chamber. After purging the gas, the chamber is controlled to be evacuated.

  With this configuration, the particles in the process chamber can be removed by neutralizing the particles in the chamber with ionized gas and then performing evacuation. Further, since the chamber can be cleaned without exposing it to the atmosphere, the maintenance time can be greatly shortened. Note that various configurations of the electron beam inspection apparatus described above can be applied to the cleaning apparatus of the present invention.

  The present invention neutralizes particles generated by stage driving or electron beam irradiation with ionized gas, and then evacuates to open the process chamber to the atmosphere without wiping work. It is possible to remove the particles.

FIG. 3 is an elevational view showing main components of an inspection apparatus according to an embodiment of the present invention, viewed along line AA in FIG. 2. It is the top view of the main components of the inspection apparatus shown in FIG. 1, Comprising: It is the figure seen along line BB of FIG. It is a schematic sectional drawing which shows the other Example of the board | substrate carrying-in apparatus in the test | inspection apparatus of this invention which concerns on one Embodiment. It is sectional drawing which shows the mini-environment apparatus of FIG. 1, Comprising: It is the figure seen along line CC. FIG. 3 is a diagram illustrating the loader housing of FIG. 1, as viewed along line DD in FIG. 2. It is an enlarged view of a wafer rack, [A] is a side view, [B] is a sectional view taken along line EE of [A]. It is a figure which shows the modification of the support method of a main housing. It is a figure which shows the modification of the support method of a main housing. It is a schematic diagram which shows schematic structure of the electron optical apparatus of the inspection apparatus of FIG. It is a figure concerning one embodiment of the present invention. It is a figure which shows the structure for cleaning a process chamber. It is a figure which shows another example of the structure for cleaning a process chamber. It is a figure which shows another example of the structure for cleaning a process chamber. It is a figure which shows another example of the structure for cleaning a process chamber.

  A semiconductor inspection apparatus according to an embodiment of the present invention will be described below with reference to the drawings. The embodiment described below shows an example when 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 adopted as appropriate.

  1 and 2A, the main components of the semiconductor inspection apparatus 1 of the present embodiment are shown in an elevational plane and a plane.

  The semiconductor inspection apparatus 1 according to the present embodiment includes a cassette holder 10 that holds a cassette containing a plurality of wafers, a mini-environment device 20, a main housing 30 that defines a process chamber, and a mini-environment device 20. A loader housing 40 disposed between the main housing 30 and defining two loading chambers; a loader 60 for loading a wafer from the cassette holder 10 onto a stage device 50 disposed in the main housing 30; An electron optical device 70 attached to a vacuum housing, an optical microscope 3000, and a scanning electron microscope (SEM) 3002 are provided and are arranged in a positional relationship as shown in FIGS. 1 and 2A. The semiconductor inspection apparatus 1 further includes a precharge unit 81 disposed in the vacuum main housing 30, a potential application mechanism that applies a potential to the wafer, an electron beam calibration mechanism, and a wafer on the stage apparatus 50. The optical microscope 871 which comprises the alignment control apparatus 87 for performing positioning is provided. The electron optical device 70 includes a lens barrel 71 and a light source tube 7000. The internal structure of the electro-optical device 70 will be described later.

<Cassette holder>
The cassette holder 10 includes a plurality of cassettes c (for example, closed cassettes such as SMIF and FOUP manufactured by Assist) in which a plurality of wafers (for example, 25 wafers) are stored in parallel with each other in the vertical direction. 2 in this embodiment). As this cassette holder, a cassette having a structure suitable for the case where the cassette is transported by a robot or the like and automatically loaded into the cassette holder 10, or an open cassette having a structure suitable for the manual loading is used. Each can be selected and installed. In this embodiment, the cassette holder 10 is of a type in which the cassette c is automatically loaded. For example, the cassette holder 10 includes an elevating table 11 and an elevating mechanism 12 that moves the elevating table 11 up and down. 2A can be automatically set in the state shown by the chain line in FIG. 2A, and after setting, the first conveyance unit 61 in the mini-environment apparatus 20 is automatically rotated to the state shown in the solid line in FIG. Directed to the pivot axis. Further, the lifting table 11 is lowered to the state shown by the chain line in FIG. As described above, the cassette holder used for automatic loading or the cassette holder used for manual loading may be a known structure as appropriate. Description is omitted.

  In another embodiment, as shown in FIG. 2B, a plurality of 300 mm substrates are accommodated in a grooved pocket (not shown) fixed inside the box body 501, and are transported, stored, etc. It is. The substrate transport box 24 is connected to a rectangular tube-shaped box body 501 and a substrate loading / unloading door automatic opening / closing device, and a substrate loading / unloading door 502 capable of opening and closing a side opening of the box body 501 by a machine, A lid 503 that is positioned on the opposite side and covers an opening for attaching and detaching the filters and fan motor, a groove-type pocket (not shown) for holding the substrate W, a ULPA filter 505, a chemical filter 506, And a fan motor 507. In this embodiment, the substrate is loaded and unloaded by the robot-type first transport unit 61 of the loader 60.

  The substrate, that is, the wafer housed in the cassette c is a wafer to be inspected, and such inspection is performed after or during the process of processing the wafer in the semiconductor manufacturing process. Specifically, a substrate that has been subjected to a film forming process, CMP, ion implantation, or the like, that is, a wafer having a wiring pattern formed on the surface, or a wafer on which a wiring pattern has not yet been formed is stored in a cassette. Since a large number of wafers accommodated in the cassette c are arranged side by side in parallel in the vertical direction, the first transfer unit 61 can be held by the first transfer unit 61 and the wafer at an arbitrary position. The arm 612 can be moved up and down.

<Mini-environment device>
1 to 3, a mini-environment device 20 includes a housing 22 that defines 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 circulation device 23 for circulating and controlling the atmosphere, a discharge device 24 for collecting and discharging a part of the air supplied into the mini-environment space 21, and a mini-environment space 21 are provided. And a pre-aligner 25 for roughly positioning a substrate to be inspected, that is, a wafer.

  The housing 22 has a top wall 221, a bottom wall 222, and a peripheral wall 223 that surrounds the 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 as shown in FIG. 3, and gas (air in this embodiment) is installed. And a gas supply unit 231 for flowing clean air in a laminar flow downwardly through one or more gas outlets (not shown), and on the bottom wall 222 in the mini-environment space 21 A recovery duct 232 that is disposed and recovers air that has flowed down toward the bottom; and a conduit 233 that connects the recovery duct 232 and the gas supply unit 231 and returns the recovered air to the gas supply unit 231. ing. In this embodiment, the gas supply unit 231 takes about 20% of the supplied air from the outside of the housing 22 and cleans it. However, 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 flow of the clean air, that is, the downward flow, that is, the downflow is mainly supplied to flow through the transport surface by the first transport unit 61 disposed in the mini-environment space 21 and is generated by the transport unit. This prevents dust having a risk of adhering to the wafer. Therefore, it is not always necessary that the downflow jet outlet is located close to the top wall as shown in the drawing, and it is sufficient if it is above the transport surface of the transport unit. Moreover, 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 the cleanliness can be provided in the mini-environment space, and the apparatus can be shut down when the cleanliness deteriorates. An entrance / exit 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 in the vicinity of the doorway 225 so that the doorway 225 is closed from the mini-environment device side. The laminar flow downflow created near the wafer 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 it.

  The discharge device 24 includes a suction duct 241 disposed below the first transfer unit 61 at a position below the wafer transfer surface of the first transfer unit 61, a blower 242 disposed outside the housing 22, And a conduit 243 connecting the suction duct 241 and the blower 242. The discharge device 24 flows down around the first transport unit 61, sucks a gas containing dust that may be generated by the first transport unit 61 through the suction duct 241, and performs a conduit 243 and a blower 242. 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 is formed on an orientation flat (referred to as a flat portion formed on the outer periphery of a circular wafer, hereinafter referred to as an orientation flat) formed on the wafer, or on the outer peripheral edge of the wafer. One or more V-shaped notches or notches are detected optically or mechanically to pre-position the rotational position around the wafer axis OO with an accuracy of about ± 1 degree. It is supposed to keep. The pre-aligner 25 constitutes a part of the mechanism for determining the coordinates of the inspection object, and is responsible for the rough positioning of the inspection object. Since the pre-aligner 25 itself may have a known structure, the description of the structure and operation is omitted.

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

<Main housing>
1 and 2A, a main housing 30 that defines a process chamber 31 includes a housing body 32, and the housing body 32 is placed on a vibration isolating device or an anti-vibration device 37 disposed on a base frame 36. It is supported by the mounted housing support device 33. The housing support device 33 includes a frame structure 331 assembled in a rectangular shape. The housing main body 32 is disposed and fixed on the frame structure 331, and is connected to the bottom wall 321 mounted on the frame structure, the top wall 322, the bottom wall 321 and the top wall 322, and surrounds the circumference. 323 for isolating the process chamber 31 from the outside. In this embodiment, the bottom wall 321 is composed of a relatively thick steel plate so as not to be distorted by weighting by equipment such as the stage device 50 placed on the bottom wall 321. Also good. In this embodiment, the housing body 32 and the housing support device 33 are assembled in a rigid structure, and vibration from the floor on which the base frame 36 is installed is transmitted to the rigid structure by the vibration isolator 37. It comes to stop. Of the peripheral wall 323 of the housing body 32, an entrance / exit 325 for taking in and out the wafer is formed in a peripheral wall adjacent to a loader housing described later.

  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. Since any of them may have a known structure, description of its own structure and function is omitted. The process chamber 31 is maintained in a vacuum atmosphere by a known vacuum device (not shown). A control device 2 that controls the operation of the entire apparatus is disposed under the base frame 36.

<Loader housing>
1, 2 </ b> A, and 4, 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 includes a bottom wall 431, a top wall 432, a peripheral wall 433 that surrounds the four circumferences, and a partition wall 434 that partitions the first loading chamber 41 and the second loading chamber 42. Can be isolated from the outside. The partition wall 434 has an opening, that is, an entrance / exit 435 for exchanging wafers between both loading chambers. In addition, entrances 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 main body 43 of the loader housing 40 is placed on and supported by the frame structure 331 of the housing support device 33. Therefore, the floor vibration is not transmitted to the loader housing 40. The entrance / exit 436 of the loader housing 40 and the entrance / exit 226 of the housing 22 of the mini-environment device 20 are aligned with each other, and there is a shutter that selectively blocks communication between the mini-environment space 21 and the first loading chamber 41. A device 27 is provided. The shutter device 27 surrounds the doorways 226 and 436 and seals 271 fixed in close contact with the side wall 433, and a door 272 that blocks air flow through the doorway in cooperation with the sealant 271. And a driving device 273 for moving the door. Further, the entrance / exit 437 of the loader housing 40 and the entrance / exit 325 of the housing main body 32 are aligned with each other, and there is a shutter device 45 that selectively blocks the communication between the second loading chamber 42 and the working chamber 31. Is provided. The shutter device 45 surrounds the entrances and exits 437 and 325, closely contacts the side walls 433 and 323, and cooperates with the sealing material 451 and the sealing material 451 that are fixed to the side walls 433 and 323. 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 communication between the first and second loading chambers. 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 structure and operation will be omitted. The support method of the housing 22 of the mini-environment device 20 and the support method of the loader housing are different, and vibrations from the floor are prevented from being transmitted to the loader housing 40 and the main housing 30 via the mini-environment device 20. Therefore, an anti-vibration cushion material may be disposed between the housing 22 and the loader housing 40 so as to airtightly surround the doorway.

  In the first loading chamber 41, a wafer rack 47 is disposed that supports a plurality (two in this embodiment) of wafers in a horizontal state with a vertical separation. As shown in FIG. 5, the wafer rack 47 includes support columns 472 that are fixed upright at four corners of a rectangular substrate 471, and two support portions 473 and 474 are formed on each support column 472. Then, the periphery of the wafer W is placed on and held on the support portion. Then, the tips of arms of first and second transfer units, which will be described later, are brought close to the wafer from between adjacent columns, and the wafer is held by the arm.

The loading chambers 41 and 42 can be controlled in a high vacuum state (the degree of vacuum is 10 ⁻⁵ to 10 ⁻⁶ Pa) by an evacuation apparatus (not shown) having a known structure including a vacuum pump (not shown). It has become. In this case, the first loading chamber 41 can be maintained as a low vacuum chamber in a low vacuum atmosphere, and the second loading chamber 42 can be maintained as a high vacuum chamber in a high vacuum atmosphere to effectively prevent wafer contamination. By adopting such a structure, a wafer which is accommodated in the loading chambers 41 and 42 and to be inspected next can be transferred into the process chamber 31 without delay. By adopting such loading chambers 41 and 42, the throughput of defect inspection is improved, and the degree of vacuum around the electron source that is required to be kept in a high vacuum state is as high as possible. Can be.

  The first and second loading chambers 41 and 42 are connected to a vacuum exhaust pipe and a vent pipe (not shown) for an inert gas (for example, dry pure nitrogen), 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 other than the inert gas from adhering to the surface). Since the apparatus for performing such an inert gas vent itself 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 the 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. An X table 53 that moves in the X direction (left-right direction in FIG. 1), a rotary table 54 that can rotate on the X table, and a holder 55 that is arranged on the rotary table 54 are provided. The wafer is releasably held on the wafer placement surface 551 of the holder 55. The holder may have a known structure capable of releasably gripping the wafer mechanically or by an electrostatic chuck method. The stage apparatus 50 uses a servo motor, an encoder, and various sensors (not shown) to operate the plurality of tables as described above, thereby causing the wafer held by the holder on the mounting surface 551 to be electro-optically. Positioning can be performed with high accuracy in the X direction, Y direction, and Z direction (vertical direction in FIG. 1) with respect to the electron beam emitted from the apparatus 70, and further in the direction around the vertical axis (θ direction) on the support surface of the wafer. It is like that. For positioning in the Z direction, for example, the position of the mounting surface on the holder may 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 interference distance measuring device using the principle of an interferometer) using a fine-diameter laser, and the position is controlled by a feedback circuit (not shown). Instead, the position of the notch or orientation flat of the wafer is measured to detect the planar position and the rotational position of the wafer with respect to the electron beam, and the rotary table is rotated by a stepping motor capable of controlling a minute angle or the like. Servo motors 521 and 531 for the stage device 50 and encoders 522 and 532 are disposed outside the main housing 30 in order to prevent dust generation in the process chamber as much as possible. Note that the stage device 50 may have a known structure used in, for example, a stepper and the like, and a detailed description of the structure and operation will be omitted. Also, since the laser interference distance measuring device may have a known structure, detailed description of the structure and operation is omitted.

  Standardization of signals indicating wafer rotation position and X / Y position obtained during inspection by inputting the rotation position and X / Y position of the wafer with respect to the electron beam in advance to a signal detection system or image processing system described later. Can also be planned. Further, the wafer chuck mechanism provided in the holder is adapted to apply a voltage for chucking the wafer to the electrode of the electrostatic chuck, and has three points (preferably equally spaced in the circumferential direction) on the outer periphery of the wafer. It is designed to press and hold (separated). The wafer chuck mechanism includes two fixed positioning pins and one pressing clamp pin. The clamp pin can realize automatic chucking and automatic release, and constitutes a conduction point for voltage application.

  In this embodiment, the table that moves in the horizontal direction in FIG. 2A is the X table and the table that moves in the vertical direction is the Y table. However, the table that moves in the horizontal direction in FIG. The moving table may be an X table.

<Loader>
The loader 60 includes a robot-type first transfer unit 61 arranged in the housing 22 of the mini-environment device 20 and a robot-type second transfer unit 63 arranged in the second loading chamber 42. I have.

The first transport unit 61 has a multi-node arm 612 that is rotatable about the axis O ₁ -O ₁ with respect to the drive unit 611. As the multi-node arm, an arbitrary structure can be used, but in this embodiment, the multi-node arm has three portions which 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 drive unit 611 is a shaft that can be rotated by a drive mechanism (not shown) having a known structure provided in the drive unit 611. 613 is attached. The arm 612 can be rotated around the axis O ₁ -O ₁ by the shaft 613, and can expand and contract in the radial direction with respect to the axis O ₁ -O ₁ as a whole by relative rotation between the parts. A gripping device 616 for gripping a wafer such as a mechanical chuck or an electrostatic chuck having a known structure is provided at the tip of the third portion farthest from the shaft 613 of the arm 612. The drive unit 611 can be moved in the vertical direction by an elevating mechanism 615 having a known structure.

  The first transfer unit 61 has an arm extending in one direction M1 or M2 of the two cassettes c in which the arm 612 is held by the cassette holder 10, and arms the wafers accommodated in the cassette c. On the top of the arm or gripped by a chuck (not shown) attached to the tip of the arm. Thereafter, the arm contracts (as shown in FIG. 2A), and the arm rotates to a position where it can extend in the direction M3 of the pre-aligner 25 and stops at that position. Then, the arm 612 extends again and the wafer held by the arm 612 is placed on the pre-aligner 25. After receiving the wafer from the pre-aligner 25 in the opposite direction, the arm 612 further rotates and stops at a position (direction M4) where the arm 612 can extend toward the second loading chamber 41, and the wafer in the second loading chamber 41 is stopped. The wafer is delivered to the rack 47. When the wafer is mechanically gripped, the peripheral edge of the wafer (in the range of about 5 mm from the peripheral edge) is gripped. This is because a device (circuit wiring) is formed on the entire surface of the wafer except for the peripheral portion, and if this portion is gripped, the device is broken or a defect is generated.

  The second transfer unit 63 is basically the same in structure as the first transfer unit 61, and is different only in that the wafer is transferred between the wafer 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 transfer wafers from the cassette held in the cassette holder 10 onto the stage device 50 disposed in the process chamber 31 and vice versa. The arm of the transfer unit moves up and down while keeping it in a horizontal state, simply taking out the wafer from the cassette and inserting it into the cassette, placing the wafer on the wafer rack and taking it out from the wafer rack, and the wafer. This is only at the time of mounting on the stage device 50 and taking it out from the stage device 50. Therefore, a large wafer, for example, a wafer having a diameter of 30 cm or 45 cm, can be moved smoothly.

<Wafer transfer>
Next, the transfer of the wafer from the cassette c supported by the cassette holder 10 to the stage device 50 disposed in the process chamber 31 will be described in order.

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

  When the cassette is aligned with the entrance / exit 225, a cover (not shown) provided in the cassette c is opened, and a cylindrical cover is disposed between the cassette c and the entrance / exit 225 of the mini-environment. The inside of c and the mini environment space 21 is shut off from the outside. Since these structures are publicly known, detailed description of the structure and operation is omitted. When a shutter device that opens and closes the entrance / exit 225 is provided on the mini-environment device 20 side, the shutter device operates to open the entrance / exit 225.

  On the other hand, the arm 612 of the first transport unit 61 is stopped in a state facing in either the direction M1 or M2 (in this description, the direction of M2). One of the wafers stored in the wafer is received. In this embodiment, the vertical position adjustment of the arm 612 and the wafer to be taken out from the cassette c is performed by the vertical movement of the driving unit 611 and the arm 612 of the first transfer unit 61. You may carry out by the up-and-down movement of the raising / lowering table 11, or you may perform both.

When the receipt of the wafer by the arm 612 is completed, the arm 612 is contracted, the shutter device is operated to close the entrance / exit (when there is a shutter device), and then the arm 612 is rotated around the axis O ₁ -O _1. It will be in the state which can expand | extend toward the direction M3. Then, the arm 612 extends, and the wafer 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 wafer (direction around the central axis perpendicular to the wafer plane). Position within a predetermined range. When the positioning is completed, the first transfer unit 61 receives the wafer 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 extends to place the wafer on the upper stage side or the lower stage side of the wafer rack 47 in the first loading chamber 41. Note that the opening 435 formed in the partition wall 434 is closed in an airtight state by the door 461 of the shutter device 46 before the shutter device 27 is opened and the wafer is transferred to the wafer rack 47 as described above.

  During the wafer transfer process by the first transfer unit 61, clean air flows in a laminar flow (as a down flow) from the gas supply unit 231 provided on the housing 22 of the mini-environment device 20. Dust is prevented from adhering to the upper surface of the wafer. Part of the air around the transport unit 61 (in this embodiment, air that is mainly dirty 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 out of the housing. . The remaining air is recovered via a recovery duct 232 provided at the bottom of the housing 22 and returned to the gas supply unit 231 again.

  When a wafer is loaded on the wafer rack 47 in the first loading chamber 41 of the loader housing 40 by the first transfer unit 61, the shutter device 27 is closed and the loading chamber 41 is sealed. Then, after the inert gas is expelled in the first loading chamber 41 and the air is expelled, the inert gas is also discharged and the inside of the loading chamber 41 is made a vacuum atmosphere. The vacuum atmosphere in the first loading chamber 41 may be a low degree of vacuum. When the degree of vacuum in the loading chamber 41 is obtained to some extent, the shutter device 46 operates to open the entrance / exit 435 sealed by the door 461, the arm 632 of the second transfer unit 63 extends, and the wafer is held by the gripping device at the tip. A single wafer is received from the rack 47 (mounted on the tip or held by a chuck attached to the tip). When the receipt of the wafer is completed, the arm 632 contracts, and the shutter device 46 operates again to close the doorway 435 with the door 461. Note that before the shutter device 46 is opened, the arm 632 can be extended in advance in the direction N1 of the wafer rack 47. Further, as described above, the doors 437 and 325 are closed by the door 452 of the shutter device 45 before the shutter device 46 is opened, thereby preventing communication between the second loading chamber 42 and the process chamber 31 in an airtight state. The inside of the second loading chamber 42 is evacuated.

When the shutter device 46 closes the entrance / exit 435, the inside of the second loading chamber 42 is evacuated again, and is evacuated at 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 it can extend toward the stage device 50 in the process chamber 31. On the other hand, in the stage apparatus 50 in the process chamber 31, the Y table 52 has an X axis line X ₁ through which the center line X ₀ -X ₀ of the X table 53 passes the rotation axis O ₂ -O ₂ of the second transport unit 63. -X ₁ and to approximately match the position, moves upward in FIG. 2A, Further, X table 53 is moved to a position close to the leftmost position in FIG. 2A, waiting in this state. When the second loading chamber 42 becomes substantially the same as the vacuum state of the process chamber 31, the door 452 of the shutter device 45 moves to open the entrances 437 and 325 and the arm 632 extends to hold the wafer at the tip of the arm 632. The stage device 50 in the chamber 31 is approached. Then, a wafer is placed on the placement surface 551 of the stage apparatus 50. When the placement of the wafer is completed, the arm 632 contracts and the shutter device 45 closes the entrances 437 and 325.

  The operation until the wafer in the cassette c is transferred onto the stage device 50 has been described above. To return the wafer that has been placed on the stage device 50 and completed processing from the stage device 50 into the cassette c, The reverse operation is performed. Further, in order to place a plurality of wafers on the wafer rack 47, the first transfer unit 61 performs the transfer of the wafers between the wafer rack 47 and the stage apparatus 50 by the second transfer unit 63. Wafers can be transferred between the cassette c and the wafer rack 47, and inspection processing can be performed efficiently.

  Specifically, when there are already processed wafers A and unprocessed wafers B in the wafer rack 47, (1) First, the unprocessed wafers B are moved to the stage device 50, and the process is started. 2) During this process, the processed wafer A is moved from the stage apparatus 50 to the wafer rack 47 by the arm 632, and the unprocessed wafer C is extracted from the wafer rack 47 by the arm 632 and positioned by the pre-aligner 25. Move to the wafer rack 47 of the loading chamber 41. In this way, in the wafer rack 47, the processed wafer A can be replaced with the unprocessed wafer C while the wafer B is being processed.

  Further, depending on how to use such an apparatus for performing inspection and evaluation, a plurality of stage apparatuses 50 are placed in parallel, and a plurality of wafers are transferred by moving wafers from one wafer rack 47 to each apparatus. Simultaneous processing is also possible.

  6 and 7 show a modified example of the method for supporting the main housing. In the modification shown in FIG. 6, the housing support device 33a is formed of a thick and rectangular steel plate 331a, and the housing body 32a is placed on the steel plate. Therefore, the bottom wall 321a of the housing body 32a has a thin structure as compared with the bottom wall of the above embodiment. In the modification shown in FIG. 7, the housing body 32b and the loader housing 40b are suspended and supported by the frame structure 336b of the housing support device 33b. Lower ends of the plurality of vertical frames 337b fixed to the frame structure 336b are fixed to four corners of the bottom wall 321b of the housing main body 32b, and the peripheral wall and the top wall are supported by the bottom wall. The vibration isolator 37b is disposed between the frame structure 336b and the base frame 36b. The loader housing 40 is also suspended by a suspension member 49b fixed to the frame structure 336. In the modification shown in FIG. 7 of the housing main body 32b, since it is supported in a suspended manner, the center of gravity of the main housing and the various devices provided therein can be lowered. In the main housing and loader housing support methods including the above-described modifications, vibrations from the floor are not transmitted to the main housing and the loader housing.

  In another variant not shown, only the housing body of the main housing is supported from below by the housing support device, and the loader housing can be placed on the floor in the same way as the adjacent mini-environment device 20. In yet another modification, not shown, only the housing body of the main housing is supported in a suspended manner on the frame structure, and the loader housing can be placed on the floor in the same manner as the adjacent mini-environment device 20.

According to the above embodiment, the following effects can be obtained.
(A) An overall configuration of a mapping projection type inspection apparatus using an electron beam is obtained, and an inspection object can be processed with high throughput.
(B) Inspecting the inspection object while monitoring the dust in the space by providing a sensor for observing the cleanliness by supplying a clean gas to the inspection object in the mini-environment space to prevent the adhesion of dust. Can do.
(C) Since the loading chamber and the process 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>
The electro-optical device 70 includes a lens barrel 71 fixed to the housing main body 32, and includes a primary light source optical system (hereinafter simply referred to as “primary optical system”) 72 as schematically illustrated in FIG. And a secondary electron optical system (hereinafter simply referred to as “secondary optical system”) 74, and a detection system 76. The primary optical system 72 is an optical system that irradiates light on the surface of the wafer W to be inspected, and includes a light source 10000 that emits light and a mirror 10001 that changes the angle of the light. In this embodiment, the optical axis of the light beam 10000A emitted from the light source is inclined with respect to the optical axis of the photoelectrons emitted from the wafer W to be inspected (perpendicular to the surface of the wafer W). The detection system 76 includes a detector 761 and an image processing unit 763 arranged on the image plane of the lens system 741.

<Light source (light source)>
In this embodiment, a DUV laser light source is used as the light source 10000. A DUV laser beam is emitted from the DUV laser light source 10000. Note that other light sources may be used as long as they emit light electrons from a substrate irradiated with light from the light source 10000, such as UV, DUV, EUV light and laser, and X-ray and X-ray laser.

<Primary optical system>
The primary optical system 72 forms a primary light beam by the light beam emitted from the light source 10000 and irradiates a rectangular or circular (may be an ellipse) beam on the wafer W surface. A light beam emitted from the light source 10000 passes through the objective lens optical system 724 and is irradiated to the wafer W on the stage device 50 as a primary light beam.

<Secondary optical system>
A two-dimensional image by photoelectrons generated by light rays irradiated on the wafer W passes through a hole formed in the mirror 10001, and is connected at a field stop position through a numerical aperture 10008 by electrostatic lenses (transfer lenses) 10006 and 10009. The image is magnified and projected by the lens 741 at the subsequent stage, and detected by the detection system 76. This imaging projection optical system is called a secondary optical system 74.

  At this time, a negative bias voltage is applied to the wafer W. Photoelectrons generated from the sample surface are accelerated by the potential difference between the electrostatic lens 724 (lenses 724-1 and 724-2) and the wafer W, and the chromatic aberration is reduced. The extraction electric field in the objective lens optical system 724 is 3 kV / mm to 10 kV / mm, which is a high electric field. Increasing the extraction electric field has the effect of reducing aberrations and improving the resolution. On the other hand, when the extraction electric field is increased, the voltage gradient increases and discharge is likely to occur. Therefore, it is important to select an appropriate value for the extraction electric field. The electrons expanded to the specified magnification by the lens 724 (CL) are converged by the lens (TL1) 10006 to form a crossover (CO) on the numerical aperture 10008 (NA). Further, zooming at a magnification can be performed by combining the lens (TL1) 10006 and the lens (TL2) 10009. Thereafter, the image is magnified and projected by a lens (PL) 741 and formed on an MCP (Micro Channel Plate) in the detector 761. In this optical system, an NA is arranged between TL1 and TL2, and an optical system that can reduce off-axis aberrations is configured by optimizing the NA.

<Detector>
The photoelectron image from the wafer imaged by the secondary optical system is first amplified by the MCP, and then hits the fluorescent screen to be converted into a light image. The principle of MCP is a bundle of millions of very thin conductive glass capillaries having a diameter of 6 to 25 μm and a length of 0.24 to 1.0 mm, which are shaped into a thin plate and applied with a predetermined voltage. Thus, each capillary functions as an independent electronic amplifier and forms an electronic amplifier as a whole.

  The image converted into light by this detector is one-to-one on a TDI (Time Delay integration) -CCD (Charge Coupled Device) in a FOP (Fiber Optical Plate) system placed in the atmosphere through a vacuum transmission window. Is projected. As another method, a fluorescent material-coated FOP is connected to the TDI sensor surface, and a signal obtained by electronic / optical conversion in a vacuum is introduced into the TDI sensor. This is more efficient for transmittance and MTF (Modulation Transfer Function) than when placed in the atmosphere. For example, high values of “× 5” to “× 10” are obtained in the transmittance and MTF. At this time, as described above, MCP + TDI may be used as the detector, but EB (Electron Bombardment) -TDI or EB-CCD may be used instead. When EB-TDI is used, photoelectrons generated from the sample surface and forming a two-dimensional image are directly incident on the EB-TDI sensor surface, so that an image signal can be formed without degradation in resolution. For example, in the case of MCP + TDI, after electronic amplification by MCP, electron / light conversion is performed by a fluorescent material, a scintillator or the like, and information on the optical image is delivered to the TDI sensor. On the other hand, in EB-TDI and EB-CCD, there are no electronic / optical conversion and light-enhanced information transmission parts / losses, so there is no image degradation and the signal reaches the sensor. For example, when MCP + TDI is used, the MTF and contrast are ½ to １ ／ compared to when EB-TDI or EB-CCD is used.

  In this embodiment, it is assumed that a high voltage of 10 to 50 kV is applied to the objective lens system 724 and the wafer W is installed.

<Relationship between main functions of map projection method and explanation of its overall image>
FIG. 9 shows an overall configuration diagram of the present embodiment. However, a part of the configuration is omitted. In FIG. 9, the electro-optical device has a lens barrel 71, a light source tube 7000, and a chamber 32. A light source 10000 is provided inside the light source tube 7000, and the primary optical system 72 is disposed on the optical axis of the light beam (primary light beam) emitted from the light source 10000. The electron optical device 70 has a tube 701 for setting a reference voltage field when performing trajectory formation of an electron beam, and the optical axis of the primary beam passes through the tube 701. A stage device 50 is installed inside the chamber 32, and a wafer W is placed on the stage device 50.

  Inside the lens barrel 71, on the optical axis of the secondary beam emitted from the wafer W, a cathode lens 724 (724-1 and 724-2), transfer lenses 10006 and 10009, a numerical aperture (NA) 10008, A lens 741 and a detector 761 are arranged. The numerical aperture (NA) 10008 corresponds to an aperture stop, and is a thin plate made of metal (such as Mo) having a circular hole. The electron optical device has tubes 702 to 704 for setting a reference voltage field for taking out secondary charged particles emitted from the wafer W and carrying them to the detector 761, and the secondary charged particles are in the tubes 702 to 704. Pass through.

  The output of the detector 761 is input to the control unit 780, and the output of the control unit 780 is input to the CPU 781. A control signal from the CPU 781 is input to the light source control unit 71 a, the lens barrel control unit 71 b, and the stage drive mechanism 56. The light source control unit 71a controls the power source of the light source 10000, and the lens barrel control unit 71b controls the lens voltage of the cathode lens 724, the lenses 10006 and 10009 and the lens 741, and the voltage control (deflection amount) of the aligner (not shown). Control).

  The stage driving mechanism 56 transmits stage position information to the CPU 781. Further, the light source cylinder 7000, the lens barrel 71, and the chamber 32 are connected to a vacuum exhaust system (not shown), and are exhausted by a vacuum pump of a vacuum exhaust system to maintain a vacuum state inside. In addition, a roughing vacuum exhaust system using a dry pump or a rotary pump is installed on the downstream side of the turbo pump.

  When the sample is irradiated with the primary light, photoelectrons are generated as a secondary beam from the light irradiation surface of the wafer W. The secondary beam passes through the cathode lens 724, the TL lens groups 10006 and 10009, and the lens (PL) 741 and is guided to the detector to form an image.

  The cathode lens 724 is composed of three electrodes. The bottom electrode is designed to form a positive electric field with the potential on the wafer W side, draw electrons (especially secondary electrons with small directivity), and efficiently guide them into the lens. Yes. Therefore, it is effective that the cathode lens 724 is bi-telecentric. The secondary beam imaged by the cathode lens 724 passes through the hole of the mirror 10001.

  If the secondary beam is imaged with only one stage of the cathode lens 724, the lens action becomes strong and aberrations are likely to occur. Therefore, a two-stage doubled lens system is used to form an image once. In this case, the intermediate image formation position is between the lens (TL 1) 10006 and the cathode lens 724. At this time, as described above, using both telecentrics is very effective in reducing aberrations. The secondary beam is converged on the numerical aperture (NA) 10008 by the cathode lens 724 and the lens (TL1) 10006 to form a crossover. An image is formed once between the cathode lens 724 and the lens (TL 1) 10006, and then the intermediate magnification is determined by the lens (TL 1) 10006 and the lens (TL 2) 10009, and is magnified by the lens (PL) 741 to be detected by the detector 761. Is imaged. That is, in this example, the image is formed three times in total.

  The lenses 10006 and 10009 and the lens 741 are all rotationally symmetric lenses called unipotential lenses or Einzel lenses. Each lens has a configuration of three electrodes. Usually, the outer two electrodes are set to zero potential, and the lens action is performed with a voltage applied to the center electrode. In addition to this lens structure, the lens 724 has a focus adjustment electrode on the first stage, the second stage, or both, or a focus adjustment electrode that is dynamically provided, and has four poles or 5 May be poles. In addition, it is also effective to use a 4-pole or 5-pole PL lens 741 in order to add a field lens function to reduce off-axis aberrations and to enlarge magnification.

  The secondary beam is enlarged and projected by the secondary optical system, and forms an image on the detection surface of the detector 761. The detector 761 includes an MCP that amplifies electrons, a fluorescent plate that converts electrons into light, a relay between the vacuum system and the outside, a lens and other optical elements for transmitting an optical image, and an image sensor (CCD, etc.) It consists of. The secondary beam forms an image on the MCP detection surface and is amplified, and the electrons are converted into an optical signal by the fluorescent plate and converted into a photoelectric signal by the imaging device.

  The control unit 780 reads the image signal of the wafer W from the detector 761 and transmits it to the CPU 781. The CPU 781 performs a pattern defect inspection from the image signal by template matching or the like. The stage device 50 can be moved in the XY directions by a stage drive mechanism 56. The CPU 781 reads the position of the stage device 50, outputs a drive control signal to the stage drive mechanism 56, drives the stage device 50, and sequentially detects and inspects images.

  Further, when the magnification is changed, a uniform image can be obtained on the entire field of view on the detection side even if the set magnification of the lens conditions of the lenses 10006 and 10009 is changed. In the present embodiment, a uniform image without unevenness can be acquired. However, usually, when the enlargement magnification is increased, the brightness of the image is lowered. Therefore, in order to improve this, when changing the magnification ratio by changing the lens condition of the secondary optical system, the lens condition of the primary optical system is set so that the amount of electrons emitted per unit pixel becomes constant. .

<Precharge unit>
As shown in FIG. 1, the precharge unit 81 is disposed adjacent to the lens barrel 71 of the electro-optical device 70 in the process chamber 31. Since this inspection apparatus is a type of apparatus that inspects the device pattern formed on the wafer surface by irradiating the substrate to be inspected, that is, the wafer, with the electron beam, the photoelectron information generated by the irradiation of the light beam is recorded on the wafer surface. As information, the wafer surface may be charged (charged up) depending on conditions such as the wafer material, the light to be irradiated, the wavelength and energy of the laser, and the like. In addition, there may be places where the wafer surface is strongly charged and weakly charged. If the charge amount on the wafer surface is uneven, the photoelectron information is also uneven, and accurate information cannot be obtained. Therefore, in this embodiment, in order to prevent this unevenness, a precharge unit 81 having a charged particle irradiation unit 811 is provided. Before irradiating light or a laser to a predetermined portion of a wafer to be inspected, charged particles are irradiated from the charged particle irradiation unit 811 of the precharge unit to eliminate uneven charging, thereby eliminating uneven charging. This charge-up of the wafer surface is detected by forming an image of the wafer surface to be detected in advance, evaluating the image, and operating the precharge unit 81 based on the detection.

<Process chamber cleaning>
FIG. 10 is a diagram illustrating a configuration for cleaning the process chamber 31. The electron beam inspection apparatus 1 includes an ionized gas generator 340 that generates ionized gas, an introduction pipe 341 that introduces the gas generated by the ionized gas generator 340 into the process chamber 31, and an introduction pipe 341. An open / close valve 342, a vacuum pump 343 for evacuating the process chamber 31, an open / close valve 345 on a conduit 344 to the vacuum pump 343, an ionized gas generator 340, open / close valves 342 and 345, and a vacuum pump 343. And a control unit 346 for controlling.

  The ionized gas generator 340 generates ionized gas. In the present embodiment, clean dry air or nitrogen is used as the gas. The controller 346 purges the ionized gas into the process chamber 31 by adjusting the opening degree of the opening / closing valve 342. Subsequently, the control unit 346 closes the open / close valve 345 on the introduction pipe 341, opens the open / close valve 342 to the vacuum pump 343, and evacuates with the vacuum pump 343.

  By purging the ionized gas in the process chamber 31 in this way, the charged particles in the process chamber 31 are neutralized, and then the vacuum chamber is evacuated to remove the particles in the process chamber 31 and perform cleaning. Can be performed. Since the cleaning can be performed without exposing the process chamber 31 to the atmosphere, the maintenance time can be greatly shortened.

  The controller 346 may repeatedly perform purging and evacuation a plurality of times, thereby removing more particles in the process chamber 31. Note that purging and evacuation may be performed in a viscous flow region. By performing purging and evacuation in the viscous flow region, the charged particles can be appropriately neutralized and removed.

  FIG. 11 is a diagram illustrating another example for cleaning the process chamber 31. In the configuration shown in FIG. 10, the ionized gas introduction pipe 341 is branched into three, and ports for introducing the ionized gas are provided at three locations. Similarly, the conduit 344 connected to the vacuum pump 343 is branched into three, and ports for evacuation are provided at three locations. Thus, by introducing ionized gas from three places, the entire process chamber 31 can be uniformly neutralized. Further, by performing evacuation at three locations, particles can be sucked out from nearby ports, so that the cleaning efficiency can be increased.

  FIG. 12 is a diagram showing another example for cleaning the process chamber 31. In the configuration shown in FIG. 12, a port for introducing ionized gas is disposed in the vicinity of the lens barrel 71 at the top of the process chamber 31, and a port for evacuating the side of the stage device 50 at the bottom of the process chamber 31 is provided. Has been placed.

  With this arrangement, the ionized gas supplied to the process chamber 31 flows downward via the stage device 50 as indicated by an arrow G in the figure. Thereby, the accumulation of ionized gas is eliminated, particles on the stage device 50 can be neutralized, and particles on the stage device 50 can be efficiently removed.

  FIG. 13 is a diagram showing another example for cleaning the process chamber 31. FIG. 13 is a view of the process chamber 31 as viewed from above. In the configuration shown in FIG. 13, a port for introducing ionized gas into one side wall of the process chamber 31 and a vacuum drawing port are arranged on the opposite side of the same side wall.

  With this arrangement, the ionized gas supplied to the process chamber 31 flows along the inner wall of the process chamber 31 as indicated by an arrow G in the figure. As a result, there is no accumulation of ionized gas, particles adhering to the inner wall can be neutralized, and particles adhering to the inner wall can be efficiently removed.

  The configuration for cleaning the process chamber 31 has been described above. In the above configuration, the control unit 346 may increase the flow rate of the ionized gas by increasing the opening degree of the opening / closing valve 342. Thereby, the particles can be removed by causing the particles adhering to the stage device 50 and the inner wall to rise.

  The control unit 346 may control the ionized gas generator 340 to alternately generate a positively charged ionized gas and a negatively charged ionized gas and introduce them into the process chamber 31. Thereby, the charging of the particles in the process chamber 31 can be neutralized regardless of whether the particles in the process chamber 31 are positively or negatively charged.

  In the present embodiment, an example in which particles in the process chamber 31 are removed has been described. However, the present invention can be applied not only to the process chamber 31 but also to another chamber. For example, the present invention can be applied to cleaning of the loading chambers 41 and 42.

  According to the present invention, there is an effect that particles can be removed without performing a wiping operation by opening the process chamber to the atmosphere, and an electron beam for inspecting a defect or the like of a pattern formed on the surface to be inspected Useful for inspection devices.

DESCRIPTION OF SYMBOLS 1 Semiconductor inspection apparatus 10 Cassette holder 20 Mini environment apparatus 30 Main housing 40 Loader housing 50 Stage apparatus 60 Loader 70 Electro-optical apparatus

Claims (7)

In an electron beam inspection apparatus that inspects the sample surface using an electron beam,
An ionized gas generator for generating ionized gas;
An introduction pipe for introducing the gas generated in the ionized gas generator flop Rosesuchanba,
An on-off valve provided on the introduction pipe;
A vacuum pump for evacuating the process chamber;
A controller for controlling the on-off valve and the vacuum pump;
With
Wherein the control unit, the after purging the ionized gas into the process chamber, have row control evacuating the process chamber,
The ionized gas generator produces a positively charged ionized gas and a negatively charged ionized gas;
The control unit is an electron beam inspection apparatus that alternately introduces a positively charged ionized gas and a negatively charged ionized gas into the process chamber .   The electron beam inspection apparatus according to claim 1, wherein the control unit repeats the purge and the evacuation in a viscous flow region. The introduction of the ionized gas, and an electron beam inspection apparatus according to claim 1 or 2 having a port for the evacuation in a plurality of locations. Electron beam inspection apparatus according to claim 3 which is disposed the ionized the port to reservoir eliminates the gas in the process chamber. The electron beam inspection apparatus according to claim 3, wherein the port is arranged so that the ionized gas flows along an inner wall of the process chamber. The electron beam inspection apparatus according to claim 1, wherein the control unit controls the flow rate of the ionized gas by controlling an opening degree of the opening / closing valve.   The electron beam inspection apparatus according to claim 1, wherein the gas is clean dry air or nitrogen.

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