JP2017123271A - Magnetic field lens, inspecting apparatus having the same, and method of manufacturing foil coil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic field lens suitable for an inspection apparatus, an inspection apparatus having a magnetic field lens, and a method for manufacturing a foil coil used for such a magnetic lens.SOLUTION: A magnetic field lens (724) for enlarging or reducing an image formed by an electron beam, includes: a yoke (92) having a gap (92a) at a position facing a course (90) of the electron beam; and a foil coil (92) which is formed of a wound thin film and provided inside the yoke (92), and the inside thereof being the course (90) of the electron beam. The thin film contains a metal film, an adhesive, and an insulation film provided between the metal film and the adhesive.SELECTED DRAWING: Figure 10B

Description

  The present invention relates to a magnetic lens for enlarging or reducing an electron beam image, an inspection apparatus having the same, and a method for manufacturing a foil coil used for such a magnetic lens.

  The conventional semiconductor inspection apparatus has been an apparatus and technology corresponding to the 100 nm design rule. However, the samples to be inspected are diversified with wafers, exposure masks, EUV masks, NIL (nanoimprint lithography) masks, and substrates, and currently, there is a need for an apparatus and technology corresponding to the design rule for samples of 5 to 30 nm. ing. That is, it is required to deal with generations in which the node of L / S (line / space) or hp (half pitch) in the pattern is 5 to 30 nm. When inspecting such a sample with an inspection apparatus, it is necessary to obtain high resolution.

  Here, “sample” refers to an exposure mask, EUV mask, nanoimprint mask (and template), semiconductor wafer, optical element substrate, optical circuit substrate, and the like. Some of these have a pattern and some have no pattern. Some of them have a pattern and some do not. Patterns with no irregularities are formed with different materials. Those without a pattern include those coated with an oxide film and those not coated with an oxide film.

International Publication No. 2002/001596 JP 2007-48686 A Japanese Patent Laid-Open No. 11-132975 JP 2012-253007 A Japanese Patent Laying-Open No. 2015-201257

  An object of this invention is to provide the magnetic lens suitable for an inspection apparatus, the inspection apparatus which has a magnetic lens, and the method of manufacturing the foil coil used for such a magnetic lens.

According to one aspect of the present invention, there is provided a magnetic lens for enlarging or reducing an image formed by an electron beam, a yoke provided with a gap at a position facing a path of the electron beam, and a wound thin film A foil coil provided inside the yoke, wherein the thin film includes a metal film, an adhesive, and an insulating film provided between the metal film and the adhesive, There is provided a magnetic field lens including a foil coil whose inside is a path of the electron beam.
According to such a configuration, since the foil coil is used instead of the linear coil, the cooling efficiency is good and the space factor of the foil coil can be increased. Therefore, it is also suitable for an inspection apparatus that uses high power.

It is desirable that a cross section of the foil coil in a plane including a path of the electron beam has a shape that matches a cross section of the yoke in the same plane.
Specifically, the yoke and the foil coil in a plane including the path of the electron beam may have a substantially trapezoidal cross section.
Thereby, the space factor of a foil coil can be made high.

The yoke is preferably provided with a cooling mechanism.
Since the foil coil has high thermal conductivity, the magnetic lens can be efficiently cooled.

A plurality of foil coils are provided inside the yoke, and the magnetic lens preferably includes a cooling mechanism provided between a certain foil coil and another foil coil.
Thereby, a magnetic lens can be cooled efficiently.

According to another aspect of the present invention, a stage device on which a sample is placed and continuously moved, a primary optical system that guides an electron beam to the sample on the stage device, and the electron beam to the sample A detector that generates an image of a secondary beam generated from the sample by irradiation; and a secondary optical system that guides the secondary beam to the detector. The primary optical system or the secondary optical system includes: There is provided an inspection apparatus including the above magnetic lens.
Such a magnetic lens has good cooling efficiency and a high space factor of the foil coil, and can be applied to an inspection apparatus.

According to another aspect of the present invention, there is provided a method of manufacturing a foil coil having a substantially trapezoidal cross section by winding a substantially trapezoidal thin film.
According to this method, when the yoke has a trapezoidal cross section, a foil coil having a substantially trapezoidal cross section can be manufactured.

According to another aspect of the present invention, a foil coil having a substantially trapezoidal cross section, comprising: a step of winding a rectangular thin film into a cylindrical shape; and a step of obliquely cutting the thin film wound into a cylindrical shape. A method of manufacturing is provided.
This method can also produce a foil coil having a substantially trapezoidal cross section when the yoke has a trapezoidal cross section.

  According to the present invention, the cooling efficiency of the magnetic lens can be improved, and the space factor of the foil coil in the magnetic lens can be increased, which is suitable for an inspection apparatus. In addition, a foil coil that matches the shape of the yoke in the magnetic lens can be manufactured.

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 which concerns on one Embodiment of this invention. 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 a light irradiation type electron optical apparatus. It is a figure which concerns on one Embodiment of this invention, and is a figure which shows the whole structure of an inspection apparatus. It is a schematic top view of the magnetic lens 724 which concerns on 1st Embodiment. It is sectional drawing of the magnetic field lens 724 in the plane (AA line of FIG. 10A) containing the course 90 of an electron beam. It is a figure explaining the foil coil. It is sectional drawing of the magnetic field lens 724 'which concerns on 2nd Embodiment. It is a figure which shows an example of the manufacturing method of foil coil 91 'of FIG. It is a figure which shows an example of the manufacturing method of foil coil 91 'of FIG. It is a figure which shows another example of the manufacturing method of foil coil 91 'of FIG. It is a figure which shows another example of the manufacturing method of foil coil 91 'of FIG. It is sectional drawing of the magnetic field lens 724 '' concerning a 3rd embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings as a semiconductor inspection apparatus for inspecting a substrate, that is, a wafer having a pattern formed as an inspection target, that is, a wafer. The following embodiments are examples of the inspection apparatus and the inspection method of the present invention, and are not limited to these, and can be applied to, for example, an exposure mask or any other sample.

  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 that stores a plurality of wafers, a mini-environment device 20, a main housing 30 that defines a working 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 83 (shown in FIG. 14) for applying a potential to the wafer, an electron beam calibration mechanism 85, And an optical microscope 871 constituting an alignment controller 87 for positioning the wafer on the stage device. 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. The cassette holder 10 includes, for example, an elevating table 11 and an elevating mechanism 12 that moves the elevating tail 11 up and down. 2A can be automatically set in the state shown by the chain line in FIG. 2A, and after the setting, it is automatically rotated to the state shown in the solid line in FIG. 2A to rotate the first transport unit in the mini-environment device. Directed to the 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 filters and a 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 transfer unit 612 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 in parallel in the vertical direction, the first transfer unit can be held by a wafer at an arbitrary position and a first transfer unit described later. The arm 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 shields 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 disposed on the bottom wall 222 in the mini-environment space A recovery duct 232 that 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. Yes. 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, is mainly supplied to flow through the transfer surface of the first transfer unit, which will be described later, disposed in the mini-environment space 21, and is generated by the transfer unit. This prevents dust that may be adhered 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.

  The discharge device 24 includes a suction duct 241 disposed below the transfer unit at a position below the wafer transfer surface of the transfer unit, a blower 242 disposed outside the housing 22, a suction duct 241, and a blower 242. And a conduit 243 for connecting the two. The discharge device 24 sucks a gas containing dust that may flow around the transport unit and may be generated by the transport unit through the suction duct 241, and the outside of the housing 22 through the conduits 243 and 244 and the blower 242. To discharge. In this case, the air may be discharged into an exhaust pipe (not shown) drawn near the housing 22.

  The aligner 25 disposed in the mini-environment space 21 is formed on an orientation flat formed on the wafer (referred to as a flat portion formed on the outer periphery of a circular wafer, hereinafter referred to as an orientation flat) 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 constitutes a part of the mechanism for determining the coordinates of the inspection object of the invention described in the claims, and is responsible for the rough positioning of the inspection object. Since this pre-aligner itself may have a known structure, description of its structure and operation is omitted.

  Although not shown, a recovery duct for a discharge device may be provided at the lower portion of the pre-aligner so that air containing dust discharged from the pre-aligner is discharged to the outside.

<Main housing>
1 and 2A, a main housing 30 that defines a working chamber 31 includes a housing body 32, and the housing body 32 is placed on a vibration shielding device or vibration isolation 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 to isolate the working chamber 31 from the outside. In this embodiment, the bottom wall 321 is made of a relatively thick steel plate so as not to be distorted by weighting by a device such as a stage device placed on the bottom wall 321. Good. In this embodiment, the housing body and the housing support device 33 are assembled in a rigid structure, and vibrations from the floor on which the base frame 36 is installed are prevented from being transmitted to the rigid structure by the vibration isolator 37. It is supposed to be. 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 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 working 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. A shutter device for selectively preventing communication between the mini-environment space 21 and the first loading chamber 41 is aligned with the entrance / exit 436 of the loader housing 40 and the entrance / exit 226 of the housing 22 of the mini-environment 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 in order to prevent vibration from the floor from being transmitted to the loader housing 40 and the main housing 30 via the mini-environment device. In addition, 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 chamber and to be inspected next can be transferred into the working chamber without delay. By adopting such a loading chamber, 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 made as high as possible. Can do.

  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. It can be positioned with high accuracy in the X direction, Y direction, and Z direction (up and down direction in FIG. 1) with respect to the electron beam irradiated from the apparatus, and further in the direction around the vertical axis (θ direction) on the wafer support surface. It has become. 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. In order to prevent the generation of dust in the working chamber as much as possible, the servomotors 521 and 531 for the stage device and the encoders 522 and 532 are arranged outside the main housing 30. Note that the stage device 50 may have a known structure used in, for example, a stepper, and the detailed description of the structure and operation is omitted. Also, since the laser interference distance measuring device may have a known structure, detailed description of the structure and operation is omitted.

  It is also possible to standardize a signal obtained by inputting the rotation position of the wafer with respect to the electron beam and the X and Y positions in advance to a signal detection system or an image processing system described later. 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 crank 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.

  In the first transfer unit 61, the arm extends in one direction M1 or M2 of the two cassettes c in which the arm 612 is held by the cassette holder, and one wafer is stored in the cassette c. It is taken out by holding it on an arm or holding it with 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 extends again and the wafer held by the arm is placed on the pre-aligner 25. After receiving the wafer from the pre-aligner in the reverse direction, the arm further rotates and stops at a position (direction M4) where the arm can extend toward the second loading chamber 41, and the wafer receiver 47 in the second loading chamber 41. Deliver the wafer. 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, and is different only in that the wafer is transferred between the wafer rack 47 and the mounting surface of the stage apparatus. Therefore, detailed description is omitted.

  In the loader 60, the first and second transfer units 61 and 63 transfer the wafer from the cassette held in the cassette holder onto the stage device 50 disposed in the working chamber 31 and vice versa. The arm of the transfer unit is moved up and down while maintaining the state. The wafer unit is simply taken out from the cassette and inserted into the cassette, placed on the wafer rack and taken out from the wafer rack, and the wafer stage device. Only when placed on and taken out of. Therefore, a large wafer, for example, a wafer having a diameter of 30 cm can be moved smoothly.

<Wafer transfer>
Next, the transfer of the wafer from the cassette c supported by the cassette holder to the stage device 50 disposed in the working 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 on the cassette is opened, and a cylindrical cover is disposed between the cassette c and the entrance / exit 225 of the mini-environment, so Shield the environment space 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 M1). One of the wafers stored in the wafer is received. In this embodiment, the vertical position adjustment between the arm and the wafer to be taken out from the cassette is performed by the vertical movement of the driving unit 611 and the arm 612 of the first transfer unit 61. It may be performed up and down or both.

  When the reception of the wafer by the arm 612 is completed, the arm contracts and operates the shutter device to close the entrance / exit (if there is a shutter device), and then the arm 612 rotates around the axis O1-O1 in the direction M3. It will be in the state where it can extend toward. Then, the arm extends and is placed on the tip or held by the chuck, the wafer is placed on the pre-aligner 25, and the pre-aligner sets the rotation direction of the wafer (the direction around the central axis perpendicular to the wafer plane) to a predetermined value. Position within range. When the positioning is completed, the transfer unit 61 receives the wafer from the pre-aligner 25 at the tip of the arm and then contracts the arm so that the arm 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.

  In the wafer transfer process by the first transfer unit, clean air flows in a laminar flow (as a downflow) from the gas supply unit 231 provided on the housing of the mini-environment device, and dust is generated during transfer. Prevents adhesion to the upper surface of the wafer. A part of the air around the transport unit (in this embodiment, air 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 out of the housing. The remaining air is recovered via a recovery duct 232 provided at the bottom of the housing 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 of the first loading chamber may be a low vacuum level. When the degree of vacuum in the loading chamber 41 is obtained to some extent, the shutter device 46 operates to open the doorway 434 that has been 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. One wafer is received from the receiver 47 (mounted on the tip or held by a chuck attached to the tip). When the receipt of the wafer is completed, the arm 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. In addition, 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 working 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 is evacuated again, and is evacuated at a higher degree of vacuum than in the first loading chamber. Meanwhile, the arm of the second transfer unit 61 is rotated to a position where it can extend toward the stage device 50 in the working chamber 31. On the other hand, in the stage apparatus in the working chamber 31, the Y table 52 has an X axis X ₁ -X in which the center line X ₀ -X ₀ of the X table 53 passes through the rotation axis O ₂ -O ₂ of the second transport unit 63. 2 moves upward in FIG. 2A to a position substantially coincident with _1, and the X table 53 moves to a position closest to the leftmost position in FIG. 2A and stands by in this state. When the second loading chamber becomes substantially the same as the vacuum state of the working chamber, the door 452 of the shutter device 45 moves to open the entrances 437 and 325, and the tip of the arm that holds the wafer by extending the arm is in the working chamber 31. Approach the stage device. 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 contracts and the shutter device 45 closes the entrances 437 and 325.

  The above description is about the operation until the wafer in the cassette c is transported onto the stage device. However, in order to return the wafer that has been placed on the stage device and has been processed into the cassette c from the stage device, the reverse of the above. Perform the operation and return. Further, in order to place a plurality of wafers on the wafer rack 47, the cassette and the wafer rack are used in the first transfer unit while the wafer is transferred between the wafer rack and the stage apparatus in the second transfer unit. The wafer can be transferred between the two and the inspection process can be performed efficiently.

Specifically, when there are already processed wafers A and unprocessed wafers B in the wafer rack 47 of the second transfer unit,
(1) First, an unprocessed wafer B is moved to the stage apparatus 50, and processing is started. (2) During this process, the processed wafer A is moved from the stage device 50 to the wafer rack 47 by the arm, and the unprocessed wafer C is extracted from the wafer rack by the arm and positioned by the pre-aligner. The wafer rack 47 is moved.
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. The same processing can be performed.

  FIG. 6 shows a modification of the main housing support method. 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 main housing exterior 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. In yet another variant, 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.

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 working chamber are integrally supported via the vibration preventing device, it is possible to supply and inspect the inspection target to the stage device without being affected by the external environment.

<Electronic optical device>
The electron 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 and a secondary electron optical system (hereinafter referred to as “first optical system”). An optical system provided with a "secondary optical system" 74) and a detection system 76 are provided. FIG. 8 is a schematic diagram showing a schematic configuration of a “light irradiation type” electron optical device. In the electron optical device of FIG. 8 (light irradiation type electron optical device), the primary optical system 72 is an optical system that irradiates the surface of the wafer W to be inspected, a light source 10000 that emits light, and a light beam. And a mirror 10001 for changing the angle of. In this light irradiation type electro-optical device, 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). Yes.

  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 the electro-optical device of FIG. 8, 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. 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>
A portion where a primary light beam is formed by a light beam emitted from the light source 10000 and is irradiated with a rectangular or circular (may be elliptical) beam on the wafer W surface is referred to as a primary optical system. The light beam emitted from the light source 10000 passes through the objective lens optical system 724 and is irradiated on the wafer WF on the stage apparatus 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. 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, and the effect of reducing chromatic aberration is obtained. 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 becomes large 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>
A photoelectron image from a wafer imaged by the secondary optical system is first amplified by a microchannel plate (MCP) and then converted to a light image by hitting a fluorescent screen. 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 that has been subjected to 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 x5 to x10 can be obtained in 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 inspection apparatus has a lens barrel 71, a light source cylinder 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. A stage device 50 is installed inside the chamber 32, and a wafer W is placed on the stage device 50.

  On the other hand, 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, and 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.

  On the other hand, 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. The control signal of the CPU 781 is input to the light source control unit 71a, the lens barrel control unit 71b, 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 downstream 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.

  Incidentally, 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 sample 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 is both telecentric. The secondary beam imaged by the cathode lens 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) lens 10006 to form a crossover. An image is formed once between the lens 724 and the lens (TL1) 10006, and then an intermediate magnification is determined by the lens (TL1) 10006 and the lens (TL2) 10009, and is magnified by the lens (PL) 741 and is enlarged to the detector 761. Imaged. That is, in this example, the image is formed three times in total.

  The lenses 10006, 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 performs dynamically, and has four poles or 5 May be poles. It is also effective to use a 4-pole or 5-pole for the PL lens 741 in order to add a field lens function to reduce off-axis aberrations and 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, and a lens and other optical elements for transmitting an optical image, and an image sensor (CCD or the like). 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 electron optical device 70 in the working 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.

  The lens 724 included in the primary optical system 72 or the secondary optical system 74 is a zoom lens that enlarges (or reduces) an image, and a magnetic lens can be applied. For a normal magnetic lens, a linear coil wound with a copper wire is used. However, the lens 724 used in the inspection apparatus is given high power, sometimes up to 300W. In this case, there is a problem that heat is accumulated in the linear coil and it takes time until the characteristics are stabilized. Therefore, in this embodiment, the lens 724 is a magnetic field lens using a foil coil. Hereinafter, the magnetic lens 724 will be described in detail.

(First embodiment)
FIG. 10A is a schematic top view of the magnetic field lens 724 according to the first embodiment. Reference numeral 90 indicates the path of the electron beam. FIG. 10B is a cross-sectional view of the magnetic field lens 724 in a plane (AA line in FIG. 10A) including the electron beam path 90. The magnetic lens 724 includes a foil coil 91 and a yoke 92. The foil coil 91 has a cylindrical shape formed by winding a thin film coaxially, and a cavity inside thereof serves as an electron beam path 90. The yoke 92 is a magnetic path formed of a magnetic material such as iron, and a foil coil 91 is provided inside thereof. The yoke 92 has a substantially rectangular cross section, and a gap 92a facing the electron beam path 90 is provided in a part thereof.

  A magnetic field is generated in the yoke 92 by causing a current to flow through the foil coil 91 from an external control device (not shown). A magnetic field leaks from the gap 92a of the yoke 92, which causes a lens action on the electron beam. The magnification can be adjusted according to the magnitude of the magnetic field.

  FIG. 11 is a diagram for explaining the foil coil 91. As shown in the drawing, the foil coil 91 is formed by coaxially winding a rectangular thin film 91a. The thin film 91a has a height (short side) of about 11 mm and a length (long side) of about several tens of meters. The thin film 91a includes a metal film 91b such as copper, an insulating film 91c such as polyimide, and an adhesive 91d. The thicknesses of the metal film 91b, the insulating film 91c, and the adhesive 91d are about 63 to 65 μm, 3 to 4 μm, and 2 to 3 μm, respectively, and the total thickness of the thin film 91a is about 70 μm. That is, by using the foil coil 91 obtained by winding such a thin film 91a, the space factor (ratio of the metal film 91b inside the yoke 92) is about 90%.

  In the case of a linear coil, since there is a gap between the copper wires and the copper wire occupies a large area, the space factor is about 75%. In this embodiment, since the foil coil 91 is used, a space factor can be made high compared with a linear coil.

  When such a thin film 91a is wound, the metal film 91b in a certain turn and the metal film 91b in the outer turn are firmly bonded by the adhesive 91d while being insulated by the insulating film 92c.

  As shown in FIG. 10B, a cooling mechanism 93 may be provided on the outer side (for example, the upper surface) of the yoke 92. The cooling mechanism 93 may be a heat radiating plate or a mechanism for circulating cooling water. In the foil coil 91, the metal film 91 b is connected in a planar shape from the lower part to the upper part of the yoke 92. In general, the thermal conductivity of a metal film is high, for example, about 400 W / K · m in the case of copper. Therefore, the heat generated in the yoke 92 efficiently moves to the cooling mechanism 93 and is cooled by the cooling mechanism 93.

  In the case of a linear coil, since the thermal conductivity of the coating is low, about 0.1 W / K · m, the cooling efficiency is low and the heat tends to be trapped. In the present embodiment, the use of the foil coil 91 increases the cooling efficiency, and as a result, the characteristics as the magnetic field lens 724 are stabilized.

  Thus, in the first embodiment, the magnetic field lens 724 is configured using the foil coil 91. For this reason, even when the magnetic field lens 724 is used in an inspection apparatus to which large electric power is applied, high cooling efficiency and high space factor can be realized.

(Second Embodiment)
In the first embodiment described above, the yoke 92 has a rectangular cross section. However, depending on the magnetic field to be generated, the yoke may have a non-rectangular cross section such as a trapezoid. In a second embodiment described below, a magnetic lens having a foil coil suitable for such a yoke will be described.

  FIG. 12 is a cross-sectional view of the magnetic field lens 724 ′ according to the second embodiment, and is a cross-sectional view in a plane including the electron beam path 90 as in FIG. 10B. In the present embodiment, the section of the foil coil 91 ′ is also trapezoidal in accordance with the section of the yoke 92 ′ being trapezoidal. More specifically, in accordance with the inclination of the lower portion of the yoke 92 ′, the cross section of the foil coil 91 ′ has a short side 91 A and a long side 91 B substantially parallel to the electron beam path 90, and the electron beam path. The trapezoid is formed of an upper side 91C that extends in a direction orthogonal to 90 and connects the upper ends of the short side 91A and the long side 91B, and a lower side 91D that connects the lower ends of the short side 91A and the long side 91B. The lower side 91D is inclined in a direction away from the upper side 91C as it approaches the path 90 of the electron beam.

  As described above, the foil coil 91 ′ is not cylindrical, but the bottom surface is inclined, so that the gap inside the yoke 92 ′ can be reduced and the space factor of the foil coil 91 ′ can be increased.

  13A and 13B are diagrams showing an example of a method for manufacturing the foil coil 91 'of FIG. As in the first embodiment, a rectangular thin film is wound coaxially to form a cylindrical (coil having a rectangular cross section) foil coil 91 (FIG. 13A). Next, the inside of the foil coil 91 is obliquely cut along the broken line in FIG. 13A so that the cross section of the foil coil 91 becomes the trapezoid shown in FIG. As a result, a foil coil 91 'shown in FIG. 13B is formed. Specifically, a fine metal fiber processing technique can be applied. That is, the lower part of the broken line in FIG. 13A can be cut by a lathe cutting using a cutting edge 94 or the like to be tapered as shown in FIG. 13B.

  14A and 14B are diagrams showing another example of the manufacturing method of the foil coil 91 'of FIG. In this example, as shown in FIG. 14A, a trapezoidal thin film 91a 'whose lower side 91a'D is inclined is used. The short side 91a'A, the long side 91a'B, the upper side 91a'C, and the lower side 91'aD of the thin film correspond to the short side 91A, the short side 91B, the upper side 91C, and the lower side 91D of the foil coil 91 ', respectively. By winding such a thin film 91a ', a foil coil 91' shown in FIG. 12 is formed. The lower side 91a'D does not necessarily have to be inclined linearly, and may be inclined stepwise as shown in FIG. 14B.

  Thus, in the second embodiment, the cross section of the foil coil 91 'is trapezoidal. Therefore, even when the yoke 92 'has a trapezoidal cross section, the space factor can be increased.

(Third embodiment)
The embodiment described next is a magnetic lens in which a plurality of foil coils are provided inside a yoke.
FIG. 15 is a cross-sectional view of a magnetic field lens 724 ″ according to the third embodiment, and is a cross-sectional view in a plane including an electron beam path 90, as in FIG. 10B. Also in this embodiment, the yoke 92 'has a trapezoidal cross section. The magnetic lens 724 ″ includes foil coils 911 a and 911 b having a rectangular cross section and a foil coil 91 ′ having a trapezoidal cross section provided inside the yoke 92 ′. In accordance with the inclination of the lower portion of the yoke 92 ′, a foil coil 91 ′ having a trapezoidal cross section is disposed at the lowest level.

  The magnetic lens 724 '' further includes a cooling mechanism 94a provided between the foil coil 911a and the foil coil 911b, and a cooling mechanism 94b provided between the foil coil 911b and the foil coil 91 '. ing. The cooling mechanism 94b may have the same configuration as the cooling mechanism 93, for example.

  Thus, in the third embodiment, a plurality of foil coils are provided in the yoke 92 ', and a cooling mechanism is provided therebetween. Therefore, the magnetic lens 724 ″ can be cooled more efficiently.

  In the second and third embodiments described above, the cross section of the yoke is not limited to a trapezoid, but may be any shape, and the cross section of the foil coil may be a shape that matches the cross section of the yoke.

50: stage device, 72: primary optical system, 74: secondary optical system, 724, 724 ′: magnetic lens, 91, 91 ′: foil coil, 91a, 91a ′: thin film, 91b: metal film, 91c: insulation Membrane, 91d: adhesive,
92, 92 ': York, 92a: Gap, 93: Cooling mechanism, 761: Detector, W: Sample

Claims (8)

A magnetic lens for enlarging or reducing an image formed by an electron beam,
A yoke provided with a gap at a position facing the path of the electron beam;
A foil coil comprising a wound thin film and provided inside the yoke, the thin film comprising a metal film, an adhesive, and an insulating film provided between the metal film and the adhesive And a foil coil having an inner side serving as a path of the electron beam.   The magnetic field lens according to claim 1, wherein a cross section of the foil coil in a plane including a path of the electron beam has a shape that matches a cross section of the yoke in the same plane.   3. The magnetic field lens according to claim 1, wherein cross sections of the yoke and the foil coil in a plane including a path of the electron beam are substantially trapezoidal.   The magnetic lens according to claim 1, wherein the yoke is provided with a cooling mechanism. A plurality of foil coils are provided inside the yoke,
The magnetic field lens according to claim 1, further comprising a cooling mechanism provided between a certain foil coil and another foil coil. A stage device for continuously moving a sample placed thereon;
A primary optical system for guiding an electron beam to the sample on the stage device;
A detector for generating an image of a secondary beam generated from the sample by irradiating the sample with the electron beam;
A secondary optical system for guiding the secondary beam to the detector;
The primary optical system or the secondary optical system is an inspection apparatus including the magnetic field lens according to claim 1.   A method of manufacturing a foil coil having a substantially trapezoidal cross section by winding a substantially trapezoidal thin film. Winding a rectangular thin film into a cylindrical shape;
A method of manufacturing a foil coil having a substantially trapezoidal cross section.

Images