Electron gun alignment mechanism and inspection method using the alignment mechanism

Abstract

To provide an alignment mechanism that easily adjusts an electron beam emission axis of an electron gun, and an inspection method for detecting fine dust attached to a peripheral wall of a passage path of the electron beam by using the alignment mechanism.SOLUTION: An alignment mechanism adjusts the arrangement of an electron gun on a plane perpendicular to an emission direction of an electron beam from the electron gun, and adjusts an emission axis of the electron beam, and has: an external cylinder that is erected in an opening of a lens barrel in which the electron gun is provided and its internal space is brought into a vacuum state; a bellows that is arranged inside the external cylinder, and is fixed to the opening of the lens barrel at one end to communicate with the internal space of the lens barrel; and a movable part that is connected to the other end of the bellows, and air-tightly supports the electron gun on the inside of the bellows. The movable part is placed on an outer end face of the external cylinder, and is supported movably on a surface of the outer end face. The bellows allows the movable part to smoothly move with the electron beam being emitted, and the emission axis of the electron gun is easily adjusted.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an alignment mechanism for adjusting the electron beam emission axis of an electron gun, and an inspection method for detecting fine dust adhering to the peripheral wall of the passage through which the electron beam passes using the alignment mechanism.

Background Art

[0002] An electron gun mounted on an electron microscope or the like emits an electron beam to irradiate a sample. The electron beam optical system is very precisely adjusted, and it is required that the installation position of the electron gun is also accurately at a predetermined position. After replacing the filament of the electron gun or once the power is turned off and then turned on again, it is necessary to adjust the alignment again. For example, Patent Documents 1 and 2 disclose methods for aligning the emission axis of an electron beam.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, since the current value is memorized and arranged, the movement of the electron gun uses pulse motors arranged in two orthogonal directions. There is a need to more easily and freely adjust the emission axis of the electron beam while the electron beam is being generated.

[0005] In addition, if fine dust adheres to the peripheral wall of the passage through which the electron beam passes, the beam output will decrease accordingly. However, since fine dust is difficult to confirm, it is difficult to remove. There is a need to detect and remove fine dust by inspection.

[0006] The present invention has been made in view of the above problems, and provides an alignment mechanism capable of easily and freely adjusting the emission axis of an electron beam, and a fine dust detection method using the alignment mechanism.

Means for Solving the Problems

[0007] In order to solve the above problems, in one aspect of the present disclosure, there is provided an alignment mechanism for adjusting the arrangement of an electron gun that irradiates an electron beam in a plane perpendicular to the emission direction of the electron beam of the electron gun to adjust the emission axis of the electron beam of the electron gun. The alignment mechanism includes an outer cylinder erected at an opening of a lens barrel in which the electron gun is provided and the internal space is in a vacuum state, a bellows disposed inside the outer cylinder, one end of which is fixed to the opening of the lens barrel and communicates with the internal space of the lens barrel, and a movable part connected to the other end of the bellows and hermetically supporting the electron gun inside the bellows. The movable part is placed on the outer end face of the outer cylinder and is movably supported on the surface of the outer end face.

[0008] According to this aspect, the bellows enables the electron gun to be movable even when the inside of the lens barrel is in a vacuum state, and further enables the electron gun to be movable even when the electron gun is irradiating an electron beam. The movable part can be freely moved back and forth, left and right on a horizontal plane. Not only stepwise mechanical movement but also analog movement is possible. Thereby, the output axis of the electron beam can be easily and freely adjusted. Since the movable part moves using the bellows and the portion slid by the movable part is not in the vacuum, the movement of the movable part does not shorten the life of the sealing material in the vacuum or lower the degree of vacuum.

[0009] Also, in one aspect, a locking member is further provided, which is disposed between the inner peripheral surface of the outer cylinder and the outer peripheral surface of the movable part, locks the movable part, and suppresses the horizontal movement of the movable part. The inner peripheral surface and the outer peripheral surface each have a gradient surface of a plane that are arranged opposite to each other and inclined so that the distance between them increases as they move away from the lens barrel. The locking member has a pair of inclined side surfaces corresponding to the gradient surfaces of the inner peripheral surface and the outer peripheral surface, enters between the gradient surfaces, and is sandwiched by bringing the inclined side surfaces into contact with the gradient surfaces to lock the movable part, thereby constituting an alignment mechanism. According to this aspect, the locking of the movable part is facilitated by the gradient surface. Also, through the inclined surface, the locking member improves the levelness of the electron gun, the electron beam is emitted vertically, and the measurement accuracy by the electron gun is improved.

[0010] Also, in one aspect, a screw hole is formed in the outer peripheral end surface of the outer cylinder, and a fixing member that screws into the screw hole is inserted into a through hole provided in the locking member and configured to screw into the screw hole. According to this aspect, the movable part is firmly fixed in the front-rear, left-right directions, the levelness of the electron gun is improved, the electron beam is emitted vertically, and the measurement accuracy by the electron gun is improved.

[0011] Further, in a certain inspection method of the present disclosure, there is a lens barrel in which the internal space is in a vacuum state, an electron gun provided in the lens barrel for emitting an electron beam, an imaging device for imaging the electron beam, and an alignment mechanism for adjusting the arrangement by moving the electron gun in a plane perpendicular to the emission direction of the electron beam of the electron gun to adjust the emission axis of the electron beam of the electron gun. In an inspection method for detecting fine dust adhering to the peripheral wall of the passage of the electron beam in an electron beam irradiation device provided with the electron gun, the alignment mechanism includes an outer cylinder erected at the opening of the lens barrel, a bellows disposed inside the outer cylinder, one end of which is fixed to the opening of the lens barrel and communicates with the internal space of the lens barrel, and the other end of the bellows is connected to the electron gun, and the electron gun is hermetically supported inside the bellows and placed on the outer end face of the outer cylinder and movably supported on the surface of the outer end face. With the lens barrel in a vacuum state, the electron beam is emitted, and while maintaining the state in which the electron beam is emitted, the alignment mechanism is used to move along the outer shape of the peripheral wall so that at least a part of the electron beam contacts the outer shape of the peripheral wall, and while the electron beam is being emitted, the imaging device is configured to image the peripheral wall of the passage of the electron beam.

[0012] According to this aspect, since the electron gun can be moved while the electron beam is output by the alignment mechanism, it is possible to detect fine dust adhering to the peripheral wall surface of the insertion hole of the electron beam provided on the wall surface as the peripheral wall of the traveling path of the electron beam.

[0013] Further, in a certain aspect of the inspection method, the imaging device is arranged on the irradiation axis of the electron beam of the electron gun with the light receiving axis coinciding therewith so as to be able to image the irradiation shape of the electron beam. The electron beam is irradiated so as to contact the peripheral wall, and the projected shape of the peripheral wall is imaged by the imaging device as an outer shape that defines a part of the irradiation shape of the electron beam. According to this aspect, the peripheral wall can be easily inspected. Also, as the insertion hole of the electron beam, even if the wall surface is a double wall surface, if the insertion holes are of the same shape with the axes aligned, the double wall surface can be inspected at once.

Advantages of the Invention

[0014] According to the above configuration, an alignment mechanism capable of generating an electron beam and adjusting the emission axis of an electron gun, and a method for inspecting fine dust in an electron beam path using the alignment mechanism are provided.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0016] (Electron Microscope 100) Hereinafter, preferred embodiments according to the configuration of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic diagram of an electron microscope 100 including an alignment mechanism 1 according to the embodiment.

[0017] As shown in FIG. 1, the electron microscope 100 includes an electron gun 6, an electron beam control mechanism 2 including a lens mechanism for converging the electron beam EB emitted from the electron gun 6 to a predetermined portion of the sample W and a scanning mechanism for scanning the electron beam EB, and a lens barrel 3 having the electron gun 6 and the electron beam control mechanism 2 inside.

[0018] The electron microscope 100 is a scanning electron microscope (SEM) that detects secondary electrons and the like generated by irradiating a sample W with an electron beam EB emitted from an electron gun 6, and displays a sample image in synchronization with two-dimensional scanning of the electron beam EB on the sample W based on this detection signal. Secondary electrons and the like emitted from the sample W are detected by a detection means D, visualized by an imaging device (a camera C in this embodiment), and recorded.

[0019] A fluorescent film viewing port 9 is provided on the bottom surface of the lens barrel 3 directly below the electron gun 6, and the sample W is placed on the fluorescent film viewing port 9 during testing. Further below the fluorescent film viewing port 9, a camera C with its light receiving optical axis directed vertically upward is arranged, and the electron beam EB and the sample W can be imaged through the fluorescent film viewing port 9.

[0020] The configuration of the present disclosure is not limited to the application of the electron microscope 100, and is also suitable for a transmission electron microscope (TEM) that irradiates a sample W with an electron beam EB and magnifies and observes the electrons transmitted through it, an electric wire drawing device, an electron beam exposure device, and the like. In addition, although the configuration of the present disclosure is applied to the axis adjustment of the electron beam EB of the electron gun 6, it can also be applied to the emission axis adjustment of other electron beam irradiation mechanisms such as an ion gun. The configuration of the present disclosure can be applied to all of the above electron beam irradiation devices without any problems.

[0021] The lens barrel 3 has a partition wall 3b that partitions the interior, and has, as spaces partitioned by the partition wall 3b inside, an electron gun chamber 4 that houses the electron gun 6 and a control mechanism chamber 5 that houses the electron beam control mechanism 2. An opening that communicates the electron gun chamber 4 and the control mechanism chamber 5 is provided as a beam passage hole 3c in the partition wall 3b. The beam passage hole 3c is provided directly below the electron gun 6, and the electron beam EB emitted from the electron gun 6 passes through the beam passage hole 3c. Due to the characteristics of the electron microscope 100, the electron gun chamber 4 is evacuated to a vacuum (ultra-high vacuum of 10 -5 Pa or less, or extremely high vacuum of 10 -8 Pa or less) by a vacuum evacuation mechanism 8A. Similarly, the control mechanism chamber 5 is also evacuated to a vacuum by a vacuum evacuation mechanism 8B.

[0022] The beam passage hole 3c is provided with a vacuum shut-off valve 7 for sealing / unsealing the beam passage hole 3c (hereinafter referred to as opening / closing). Since it takes time to evacuate the electron microscope 100, when repairing the electron gun 6 or replacing the sample W, the vacuum shut-off valve 7 is used to perform operations while keeping the electron gun chamber 4 or the control mechanism chamber 5 under vacuum. Also, when transporting the electron microscope 100, the beam passage hole 3c is sealed with the vacuum shut-off valve 7 for transportation.

[0023] The electron gun 6 is held by an alignment mechanism 1 disposed in an upper surface opening 3a formed in the upper surface of the lens barrel 3. The alignment mechanism 1 is an emission axis adjustment mechanism of the electron gun 6. The alignment mechanism 1 can adjust the arrangement of the electron gun 6 on a plane perpendicular to the emission direction of the electron beam EB. The emission axis of the electron gun 6 is adjusted by the alignment mechanism 1, and the electron beam EB emitted from the electron gun 6 passes through substantially the center of the beam passage hole 3c provided in the partition wall 3b and reaches the sample W.

[0024] The alignment mechanism 1 is configured as a cylinder with a substantially double structure, and includes an outer cylinder 10 serving as an outer cylinder of the double cylinder, a bellows 30 serving as an inner cylinder, and a movable part 99 disposed between the two. The movable part 99 supports the electron gun 6 inside the bellows 30 and is disposed like a lid at the upper opening of the bellows 30. The movable part 99 is placed on the upper surface which is the outer end surface of the outer cylinder 10 and can move on the surface (horizontal plane) of the outer end surface. The upper end of the bellows 30 is connected to the lower part of the movable part 99. The electron gun 6 is vertically held by the movable part 99 inside the bellows 30.

[0025] The bellows 30 is a kind of spring structure made by welding metal plates, and it contracts and follows the movement of the movable part 99. When the movable part 99 moves, the bellows 30 follows, and the electron gun 6 held by the movable part 99 also moves. The lower end of the bellows 30 is fixed to the upper surface opening 3a, and the space inside the bellows 30 communicates with the internal space of the lens barrel 3. When the inside of the lens barrel 3 is in a vacuum state, the space inside the bellows 30 also becomes a vacuum state. The movable part 99 can move even when the inside of the lens barrel 3 is in a vacuum, and the electron gun 6 held inside the bellows 30 can move while remaining in a vacuum state. The movable part 99 can move even when the electron gun 6 emits an electron beam EB, and due to the movement of the movable part 99, the electron gun 6 also moves while emitting the electron beam EB.

[0026] With the above configuration, the alignment mechanism 1 can perform axis adjustment by moving the electron gun 6 in a state where the electron gun 6 outputs an electron beam EB. Using the alignment mechanism 1, the electron gun 6 is made to emit an electron beam EB, and while checking the passage of the electron beam EB, the movable part 99 is moved horizontally to adjust the emission axis of the electron gun 6.

[0027] (Alignment mechanism 1) The alignment mechanism 1 will be described in detail with reference to FIGS. 2 to 4. FIG. 2 is a perspective view of the alignment mechanism 1. FIG. 3 is a plan view of the alignment mechanism 1. FIG. 4 is a vertical cross-sectional view of the alignment mechanism 1 taken along line A-A of FIG. 3. FIGS. 2 to 4 show the state where the alignment mechanism 1 holds the electron gun 6. Note that the electron gun 6 in each figure shows only the general outer shape.

[0028] As shown in FIGS. 2 to 4, the alignment mechanism 1 includes an outer cylinder 10, a moving base 40, a holder 80, a connecting member 70, a bellows 30, and a mounting base 20, all of which are configured in a cylindrical or ring shape and have a central hole penetrating axially in the center. In the initial state, the axes of the central holes are arranged to coincide with the vertical central axis AX.

[0029] As described above, the alignment mechanism 1 has a substantially double-cylinder structure composed of an inner cylinder and an outer cylinder, and their respective central axes are arranged to coincide with the central axis AX. The outer cylinder of the double-cylinder structure is the outer cylinder 10, the inner cylinder is the bellows 30, and the electron gun 6 is vertically arranged further inside the bellows 30. The moving base 40, the holder 80, and the connecting member 70 constitute a movable part 99 for adjusting the arrangement of the electron gun 6.

[0030] The alignment mechanism 1 is provided at the upper surface opening 3a of the lens barrel 3. The upper surface opening 3a is provided directly above the beam passage hole 3c. The mounting base 20 is used for installing the alignment mechanism 1. The annular protrusion 21 provided around the edge of the opening of the mounting base 20 enters the upper surface opening 3a and fits into the upper surface opening 3a. Further, the inner hole of the outer cylinder 10 is inserted through and fitted to the outer peripheral side surface of the mounting base 20. A lens barrel screw hole 3d is provided at the edge of the outer surface of the upper surface opening 3a, and the first fixing member B1 is screwed into the lens barrel screw hole 3d to clamp the outer cylinder 10 and the mounting base 20 together, whereby the mounting base 20 and the outer cylinder 10 are fixed to the lens barrel 3. Thereby, the outer cylinder 10 is integrated with the mounting base 20, and the outer cylinder 10 stands on the outer surface of the upper surface opening 3a. In order to maintain a vacuum state, a sealing material P is arranged between the mounting base 20 and the lens barrel 3.

[0031] The lower end of the bellows 30 is connected to the upper end surface of the mounting base 20 by welding, and the upper end of the bellows 30 is connected to the lower end surface of the moving base 40 by welding. Both bases are fixed with the central axis coinciding with that of the bellows 30. When the mounting base 20 and the outer cylinder 10 are installed, the bellows 30 is arranged inside the outer cylinder 10 with the central axis coinciding with the central axis AX.

[0032] On the upper surface of the moving base 40, a plurality of first screw holes 41 for fixing the connecting member 70 and a plurality of second screw holes 42 for fixing the holder 80 are formed at equal intervals alternately in the circumferential direction. First, the connecting member 70 is placed overlapping the moving base 40, and the countersunk bolt, which is the third fixing member B3, is fastened to the first screw hole 41, thereby fixing the connecting member 70 to the moving base 40. A recess is provided in the connecting member 70 so that the bolt head of the third fixing member B3 is buried, and the third fixing member B3 does not protrude from the upper surface of the connecting member 70. Next, the holder 80 is placed overlapping the upper part of the connecting member 70. A screw insertion hole 73 corresponding to the arrangement of the second screw hole 42 is formed in the connecting member 70. Further, a screw insertion hole 82 is similarly formed in the holder 80, and the screw portion of the long bolt, which is the fourth fixing member B4, is inserted through the screw insertion holes 82 and 73 and fastened to the second screw hole 42, thereby also fixing the holder 80 to the moving base 40. Thereby, the moving base 40, the connecting member 70, and the holder 80 are integrated.

[0033] On the inner peripheral wall near the upper end opening of the outer cylinder 10, an inner flange portion 13 protruding inward is provided all around. A groove is provided all around on the upper surface of the inner flange portion 13, and the ring-shaped intervening member 60 engages with the groove. The intervening member 60 is configured such that its height is higher than the depth of the groove and its upper surface becomes horizontal when it is arranged in the groove. On the outer peripheral surface of the connecting member 70, an outer flange portion 71 protruding outward is provided all around, and the outer flange portion 71 is placed on the upper surface of the intervening member 60. Thereby, the movable portion 99 is placed on the upper surface of the inner flange portion 13. In the present embodiment, the inner flange portion 13 is provided and the intervening member 60 is arranged in the groove of the inner flange portion 13, but it is not limited thereto, and the intervening member 60 may be arranged on the outer end surface (upper surface) of the outer cylinder 10 without providing the inner flange portion.

[0034] The portion of the connecting member 70 that is sandwiched between the moving base 40 and the holder 80 is configured to be thin-walled and have a large inner diameter, and a sealing material P is disposed on the inner peripheral portion of the thin-walled portion of the connecting member 70. The holder 80 and the moving base 40 sandwich the sealing material P, and the connection portion between the moving base 40 and the holder 80 is sealed. In the present embodiment, the moving base 40, the connecting member 70, and the holder 80 that constitute the movable portion 99 are integrated and sealed in the above-described manner. However, the present invention is not limited to this, and the movable portion 99 may be configured as a single member in which these are integrated by die casting, lost wax method, or the like.

[0035] In the center of the inner hole of the holder 80, the electron gun 6 is disposed such that its emission axis is vertical, and the electron gun 6 is sealed and fixed to the holder 80 by a sealing material and a fixing member (not shown).

[0036] (Function and effect) The movable portion 99 is placed on the upper surface of the inner flange portion 13 via the intervening member 60, and the upper surface of the intervening member 60 is movable in the horizontal direction. The electron gun 6 is supported by the movable portion 99 and is held vertically and airtightly inside the bellows 30. When the movable portion 99 moves on the upper surface of the intervening member 60, the bellows 30 follows the movement, and the electron gun 6 also moves horizontally, and the axis of the electron gun 6 is adjusted.

[0037] The internal space 30a of the bellows 30 communicates with the electron gun chamber 4. When the internal space of the lens barrel 3 including the electron gun chamber 4 is evacuated to a vacuum state by the vacuum evacuation mechanisms 8A and 8B, the internal space 30a of the bellows 30 also becomes a vacuum state. When a pressure difference is generated between the electron gun chamber 4 and the outside air due to evacuation by the vacuum evacuation mechanisms 8A and 8B, a force directed inward is applied to the lens barrel 3, and a downward pulling force is also generated on the movable portion 99 connected to the bellows 30 as a part of the wall surface partitioning the internal space 30a (see the dotted arrow in FIG. 4). However, since the outer flange portion 71 is placed on the inner flange portion 13 of the standing outer cylinder 10 via the intervening member 60, the movable portion 99 is subjected to a downward load due to the pressure difference, but the downward movement is restricted.

[0038] As described above, since the bellows 30 is a kind of spring structure, it expands and contracts to follow the horizontal movement of the movable part 99. The bellows 30 is sealed, and even if the internal space of the lens barrel 3 is in a vacuum state, the movable part 99 can move horizontally, and the electron gun 6 can also move horizontally in a vacuum state. Even when the electron gun 6 emits the electron beam EB, the electron gun 6 moves inside the bellows 30 along with the movement of the movable part 99 while the electron beam EB is being emitted.

[0039] By horizontally moving the movable part 99 while causing the electron gun 6 to emit the electron beam EB, the emission axis of the electron beam EB can be adjusted while being confirmed in real time. The movable part 99 can move freely and easily in the horizontal direction. The alignment mechanism 1 can accurately align the emission axis of the electron gun 6.

[0040] The intervening member 60 is made of a copper alloy such as bronze or brass, or a relatively soft metal such as SUS304 (non-magnetic material), reducing the frictional resistance with the contacting holder 80 and suppressing the generation of dust due to sliding. Also, for friction reduction, lubricants such as molybdenum disulfide, nickel for lubrication, and grease may be used. Note that the configuration of the present disclosure can also be implemented by directly placing it on the upper surface (outer end face 17) of the outer cylinder 10 without using the intervening member 60.

[0041] The movable part 99 that holds the electron gun 6 can move even when the lens barrel 3 is in a vacuum state, and can also move even when the electron gun 6 is emitting the electron beam EB. The movable part 99 is arranged outside the lens barrel 3 and can move freely in the horizontal direction manually or automatically in a vacuum state and when the electron beam EB is being emitted. For example, not only stepwise mechanical movement using electron pulses but also continuous analog movement by hand is possible, and complex movements can be performed intuitively, facilitating the axis adjustment of the electron gun 6 and the inspections described later.

[0042] In this embodiment, the bellows 30 can be horizontally moved for each sealing surface that defines a vacuum. Also, using the intervening member 60 of the metal member, the movable part 99 is slid and moved with the contact surface with the intervening member 60 as the moving surface. For this reason, the sealing material in the vacuum is not slid. Conventionally, the movable part has been sliding while sandwiching the sealing material, and since it moves while rubbing and reducing the sealing surface of the sealing material, the sealing performance is also likely to deteriorate. This configuration that does not slide the sealing material can maintain a higher degree of vacuum in the lens barrel 3 compared to the conventional configuration, extend the life of the emitter of the electron gun 6, and also extend the life of the sealing material. In addition, by using the intervening member 60, since the movable part 99 moves on the upper surface of the intervening member 60, a high-precision flatness can be ensured. Also, since the sealing material is not slid, instead of a general sealing member such as a rubber material, a sealing member with extremely high confidentiality performance, such as a metal seal, which is also resistant to extreme temperature environments, corrosion, and radiation, and has high stability and reliability, can be used for the sealing material P. Such a sealing material also has a long replacement period. The number of times of interrupting the test for replacing the sealing material and the emitter can be reduced.

[0043] (Locking member 50 and locking screw SW) The locking member 50 and the locking screw SW will be described in detail. The locking member 50 is disposed between the inner peripheral side surface of the outer cylinder 10 and the outer peripheral surface of the movable part 99, locks both of them, and suppresses the movement of the movable part 99. The locking screw SW fastens the locking member 50 to fix the arrangement of the movable part 99.

[0044] From the inner flange portion 13 to the upper end of the outer cylinder 10, there is an enlarged diameter portion 11 whose diameter becomes larger and bulges outward. Since the outer flange portion 71 of the movable part 99 is placed on the inner flange portion 13 via the intervening member 60, the inner peripheral surface of the enlarged diameter portion 11 and the outer peripheral surface of the outer flange portion 71 face each other. Note that a configuration may be adopted in which a facing portion with the movable part 99 is provided on the inner peripheral surface of the upper end portion of the outer cylinder 10 without using the enlarged diameter portion 11.

[0045] Here, as shown in FIG. 2, the outer flange portion 71 is provided with notches 72 at four locations every 90 degrees in the circumferential direction, where the corners of the outer peripheral surface and the upper end surface of the outer flange portion 71 are linearly cut out. A plane that is formed by being cut and inclined so as to approach the central axis AX toward the upper end is referred to as an inner gradient surface 75. Similarly, the diameter-expanded portion 11 is formed with recesses 12 at four locations every 90 degrees in the circumferential direction, which are formed on the upper surface and the inner peripheral surface of the diameter-expanded portion 11. Note that these can be any number as long as they are a multiple of 4. The surface that becomes the inner peripheral surface of the recess 12 is a plane that is inclined so as to move away from the central axis AX toward the upper end, and this plane is referred to as an outer gradient surface 15. The inner gradient surface 75 and the outer gradient surface 15 are inclined from the vertical at the same angle, and the distance between the two gradients increases as it goes upward.

[0046] As shown in FIG. 4, the inner gradient surface 75 and the outer gradient surface 15 are arranged to face each other, and a locking member 50 is arranged in the space between these two gradient surfaces.

[0047] The locking member 50 is substantially a rectangular parallelepiped, and a pair of opposing side surfaces are inclined side surfaces that are inclined at the same angle as the inner gradient surface 75 and the outer gradient surface 15. The locking member 50 is arranged with the pair of inclined side surfaces aligned with the two gradient surfaces and enters between the inner gradient surface 75 and the outer gradient surface 15. The bottom surface of the locking member 50 does not contact the inner flange portion 13, and the locking member 50 is held with only the pair of inclined side surfaces contacting the inner gradient surface 75 and the outer gradient surface 15.

[0048] When four locking members 50 are respectively arranged between the two gradient surfaces, four locking members 50 enter at equal intervals between the inner peripheral side surface of the outer cylinder 10 and the outer peripheral surface of the movable portion 99, and the movement of the movable portion 99 is restricted.

[0049] When the movable part 99 moves from the initial state and the distance between the inner inclined surface 75 and the outer inclined surface 15 becomes narrower, the locking member 50 only changes its arrangement upward from the initial state and then enters between the inner inclined surface 75 and the outer inclined surface 15 as it is. Similarly, when the movable part 99 moves from the initial state and the distance between the inner inclined surface 75 and the outer inclined surface 15 becomes wider, the locking member 50 only changes its arrangement downward from the initial state and then enters between the inner inclined surface 75 and the outer inclined surface 15 as it is. For this reason, even if the movable part 99 moves from the initial state for the axis adjustment of the electron gun 6 and the distance between the inner inclined surface 75 and the outer inclined surface 15 is changed, the locking member 50 enters between the inner inclined surface 75 and the outer inclined surface 15 as a wedge to limit the movement of the movable part 99.

[0050] A vertical through hole 53 penetrating vertically is formed in the middle of the locking member 50. A locking screw hole 14 into which a locking screw SW is screwed is vertically formed in the outer end face 17 which is the upper surface of the inner flange portion 13. When the locking screw SW is inserted into the vertical through hole 53 and screwed into the locking screw hole 14 in the locking member 50 which is in contact with and held on the inner inclined surface 75 and the outer inclined surface 15, the locking member 50 is fastened to the outer cylinder 10. When the locking member 50 is fastened, the arrangement of the movable part 99 arranged in contact with the locking member 50 is also fixed, and the arrangement of the electron gun 6 held by the movable part 99 is also fixed. Note that a configuration may be adopted in which the inner flange portion 13 is not provided and the locking screw hole 14 is directly provided on the outer end face of the outer cylinder 10.

[0051] The movable part 99 is only placed on the upper surface of the intervening member 60. When the locking screw SW and the locking member 50 are attached, the movement of the locking member 50 is restricted and its arrangement is fixed. When the locking screw SW and the locking member 50 are removed, it can move on the horizontal upper surface of the intervening member 60.

[0052] The arrangement of the movable part 99 is fixed by the locking member 50 and the locking screw SW. Since it is fixed to the vertically erected outer cylinder 10, the movable part 99 is firmly fixed. In the configuration where the arrangement of the conventional electron gun is moved, the fixing of the movable part is only by its own weight and atmospheric pressure. In contrast, in the present embodiment, the movable part 99 that holds the electron gun 6 is firmly fixed in the vertical direction and the horizontal direction to the vertically erected outer cylinder 10 via the gradient surface using the locking screw SW. Thereby, high flatness is ensured, and the electron beam EB can be emitted perpendicularly to the sample W, improving the measurement accuracy.

[0053] By providing a gradient surface on the locking member movable in the adjustment direction, inserting the locking screw SW into the through hole and fixing it by screwing, it is possible to move each locking member 50 in the vertical direction and in the radial direction, facilitating adjustment and fixing.

[0054] (Method for adjusting the emission axis) Next, a method for adjusting the axis of the electron gun 6 by the alignment mechanism 1 will be described with reference to the drawings. Each drawing in FIG. 5 is part F of FIG. 4 and shows the process of axis adjustment of the alignment mechanism 1.

[0055] FIG. 5(A) shows the initial state. In the initial state, the outer cylinder 10, the bellows 30, the movable part 99, and the electron gun 6 held by the movable part 99 are arranged with their respective central axes coinciding with the central axis AX.

[0056] The vertical through hole 53 provided in the locking member 50 is an elongated hole extending in the direction toward the central axis AX (the horizontal direction in FIG. 5). This direction is the direction in which the movable part 99 can move relative to each locking member 50. The locking screw SW is inserted through the vertical through hole 53 using a washer and fastened to the locking screw hole 14. In the initial state, the locking screw SW is inserted through and fastened at approximately the center of the vertical through hole 53, and the gap between the locking screw SW and the vertical through hole 53 is uniform in the circumferential direction. The electron gun 6 can move horizontally by the amount of the gap between the locking screw SW and the vertical through hole 53.

[0057] First, as shown in Fig. 5(B), in order to move the movable part 99, the locking screw SW is removed. The remaining three locking screws SW (not shown in Fig. 5) are also removed. Next, as shown in Fig. 5(C), the locking member 50 is also removed. (Actually, neither is completely removed, but the movable part 99 is loosened to be movable.)

[0058] Then, as shown in Fig. 5(D), the movable part 99 that has become movable is moved to a desired position. In Fig. 5(D), the movable part 99 is moved to the left as the direction away from the central axis AX.

[0059] After the movable part 99 is moved to the desired position, as shown in Fig. 5(E), the locking member 50 is again placed between the two gradient surfaces in contact with the inner gradient surface 75 and the outer gradient surface 15. When the movable part 99 is moved in the direction away from the central axis AX from the initial position, the inner gradient surface 75 approaches the outer gradient surface 15, and the distance between the two gradient surfaces becomes shorter. Therefore, the locking member 50 is moved slightly upward from the initial position and in the same direction as the moving direction of the movable part 99. For example, in Fig. 5(E), since the movable part 99 is moved to the left from the initial state, the locking member 50 is arranged below and to the left of the initial state. When the movable part 99 is moved in the direction approaching the central axis from the initial position, the inner gradient surface 75 moves away from the outer gradient surface 15, and the distance between the two gradient surfaces becomes longer. Therefore, the locking member 50 is moved slightly downward from the initial position and in the direction opposite to the moving direction of the movable part 99.

[0060] Finally, as shown in Fig. 5(F), the locking screw SW is inserted through the vertical through-hole 53 and fastened to the locking screw hole 14. Since the movable part 99 has moved horizontally from the initial state, the gap with the locking screw SW becomes wider in the moving direction of the movable part 99. In Fig. 5(F), since the movable part 99 has moved to the left from the initial state, the gap between the locking screw SW and the left side of the vertical through-hole 53 has become wider.

[0061] (Method for inspecting fine dust adhering to the peripheral wall surface of the beam passage) Using the alignment mechanism 1 described above, it is possible to detect fine dust adhering to the peripheral wall of the passage of the electron beam EB. This will be described in detail with reference to FIGS. 6 and 7. FIG. 6 is a schematic explanatory view of the inspection method.

[0062] With the vacuum evacuation mechanisms 8A and 8B, the electron gun chamber 4 and the control mechanism chamber 5 are brought into a vacuum state, and the electron beam EB is emitted from the electron gun 6. While maintaining the state of emitting the electron beam EB, using the alignment mechanism 1, the electron gun 6 is moved along the outer shape of the peripheral wall of the passage of the electron beam EB, and the camera C images the peripheral wall of the passage hole of the electron beam EB. As a result, the peripheral wall that was not conventionally irradiated is illuminated by the electron beam EB, and the adhering fine dust can be detected.

[0063] As described above, inside the lens barrel 3, a partition wall 3b having a beam passage hole 3c through which the electron beam EB passes is provided. Fine dust may adhere to the peripheral wall 3e of the beam passage hole 3c, and the fine dust may interfere with a part of the electron beam EB. For this reason, as an example, FIG. 7 shows a state in which fine dust G adhering to the peripheral wall 3e defining the beam passage hole 3c through which the electron beam EB passes is detected using the camera C.

[0064] FIG. 7 is a view of the beam passage hole 3c in a state irradiated with the electron beam EB as seen from directly below (part H seen from the position of the camera C arranged directly below the electron gun 6 in FIG. 6). FIGS. 7(A0) to 7(A3) are views showing the actual state. FIGS. 7(B0) to 7(B3) are images captured by the camera C. FIGS. 7(B0) to 7(B3) correspond to FIGS. 7(A0) to 7(A3). In FIG. 7, the electron beam EB is shown in light ink. In FIGS. 7(B0) to 7(B2), the indication lines are shown in dark light ink.

[0065] Figures 7(A0) and 7(B0) show the initial state. As described above, the alignment mechanism 1 can move the electron gun 6 while irradiating the electron beam EB. As shown in Fig. 7(A0), the emission axis of the electron gun 6 is finely adjusted by the alignment mechanism 1, and the electron beam EB emitted from the electron gun 6 passes through substantially the center of the circular beam passage hole 3c. The camera C is disposed vertically below the electron gun 6 and on the extension in the extending direction of the peripheral wall 3e that defines the beam passage hole 3c, and images the entire surface of the peripheral wall 3e.

[0066] As shown in Fig. 7(B0), there is no light source in the lens barrel 3, and the camera C receives and images the electron beam EB through the phosphor film viewing port 9 sprayed with a phosphor that glows when electrons hit it. What is imaged is the irradiation shape of the electron beam EB. Even if the fine dust G adheres to the peripheral wall 3e, in the initial state, the partition wall 3b and the beam passage hole 3c cannot be imaged by the camera C, and the fine dust G cannot be confirmed from the captured image.

[0067] Therefore, first, as shown in Fig. 7(A1), using the alignment mechanism 1, the arrangement of the electron gun 6 is adjusted so that a part of the electron beam EB contacts the partition wall 3b. As a result, a part of the electron beam EB is blocked by the partition wall 3b, and the remaining part passes through the beam passage hole 3c. As shown in Fig. 7(B1), a part of the electron beam EB that has passed through the beam passage hole 3c is imaged.

[0068] The camera C is disposed vertically below the electron gun 6, that is, on the irradiation axis of the electron beam EB, with its light receiving axis aligned with the irradiation axis, so that the irradiation shape of the electron beam can be imaged. When the electron beam EB is irradiated so as to contact the peripheral wall 3e, the projected shape of the peripheral wall 3e is imaged by the camera C as an outer shape that defines a part of the irradiation shape of the electron beam EB.

[0069] As shown in the figure, a part of the circular electron beam EB is blocked by the partition wall 3b, and a part of the circular irradiation shape of the electron beam EB, which is defined by the peripheral wall 3e, is imaged as the irradiation shape of the rugby ball-shaped electron beam EB. In this way, as a part of the outer shape of the electron beam EB, a part of the peripheral wall 3e that blocks the irradiation can also be confirmed in the captured image. As shown in FIG. 6, the partition wall in the lens barrel 3 is provided in duplicate, and the second beam passage hole 3g provided in the second partition wall 3f has the same shape as the beam passage hole 3c and is provided with the axes aligned. Therefore, from the camera C, they almost look the same. For this reason, the second peripheral wall 3h of the second beam passage hole 3g can also be imaged and inspected at the same time. For the sake of convenience, it is assumed that only the partition wall 3b exists, and in FIG. 7 and its description, only the partition wall 3b is limited for the description.

[0070] Next, as shown in FIGS. 7(A2) to (A3), with the alignment mechanism 1, the electron gun 6 is moved along the outer shape of the peripheral wall 3e (the shape of the beam passage hole 3c) while the electron beam EB is being emitted. In FIG. 7(B1), the outer shape of the beam passage hole 3c is generally grasped, and the electron gun 6 is moved along the peripheral wall 3e to block a part of the electron beam EB, so that the peripheral wall 3e is confirmed as a part of the outer shape of the irradiation shape of the electron beam EB to be imaged.

[0071] As shown in FIG. 7(A3), when the fine dust G adheres to the peripheral wall 3e, the fine dust G also blocks the irradiation of the electron beam EB. As a result, the electron beam EB may be bent. As shown in FIG. 7(B3), since the fine dust G blocks the irradiation of the electron beam EB, a part of the outer shape of the rugby ball shape of the electron beam EB is imaged in a state of being recessed by the fine dust G. In this way, the fine dust G can be confirmed in the captured image as a shadow that blocks a part of the irradiation shape of the electron beam EB.

[0072] If fine dust adheres to the peripheral wall of the passage of the electron beam EB, the electron beam output will decrease due to being blocked by the fine dust. By using the alignment mechanism 1, while emitting the electron beam EB, the electron gun 6 is moved so as to be engaged with the peripheral wall and imaged by an imaging device, thereby enabling inspection of whether fine dust adheres to the peripheral wall. When fine dust is discovered, by grasping its size and position and making a comprehensive judgment considering the urgency and the degree of influence on the test, it can be appropriately removed.

[0073] In the present embodiment, it is provided so as to coincide with the central axis of the beam passage hole 3c which is the beam passage of the electron beam EB, the light receiving axis of the camera C is arranged along the axis of the electron gun 6, and the camera C images the irradiation shape of the electron beam EB and the projected shape of the peripheral wall 3e. When the electron beam EB is irradiated so as to be engaged with the peripheral wall 3e, the peripheral wall 3e is imaged by the camera C as an outer shape that defines a part of the irradiation shape. If fine dust G adheres to the peripheral wall 3e, the fine dust G becomes a convex portion formed on the peripheral wall 3e, and the fine dust G is imaged by the camera C as a concave portion formed on the outer shape of the irradiation shape of the electron beam EB. By moving the movable portion 99 along the edge of the peripheral wall 3e, the entire surface of the peripheral wall 3e can be inspected.

[0074] In this configuration, while emitting the electron beam EB, it can be freely adjusted over a relatively wide range on a horizontal plane. The electron gun 6 can be moved horizontally to a position where it reaches the portion where the insertion hole of the electron beam EB is located, and by using this, the emission axis is moved to the portion where the insertion hole of the electron beam EB, that is, the peripheral wall surface of the passage of the electron beam EB is located, and by moving along this peripheral wall surface, fine dust adhering to the peripheral wall of the passage of the electron beam EB can be detected.

[0075] As described above, the preferred embodiments of the present invention have been described, but it is also possible to make modifications based on the knowledge of those skilled in the art, and such forms are included in the scope of the present invention.

Explanation of reference numerals

[0076] 1: Alignment mechanism 3: Lens barrel 3a: Upper opening (opening) 3e: Peripheral wall 6: Electron gun 10: Outer cylinder 14: Locking screw hole (screw hole) 15: Outer gradient surface (gradient surface) 17: Outer end face 30: Bellows 50: Locking member 53: Vertical through hole (through hole) 75: Inner gradient surface (gradient surface) 99: Movable part C: Camera (imaging device) EB: Electron beam G: Fine dust SW: Locking screw (fixing member)

Claims

1. An alignment mechanism for adjusting the arrangement of an electron gun that irradiates an electron beam in a plane perpendicular to the emission direction of the electron beam of the electron gun to adjust the emission axis of the electron beam of the electron gun, comprising: an outer cylinder erected at an opening of a lens barrel provided with the electron gun and having an internal space in a vacuum state; a bellows disposed inside the outer cylinder, one end of which is fixed to the opening of the lens barrel and communicates with the internal space of the lens barrel; a movable part connected to the other end of the bellows and hermetically supporting the electron gun inside the bellows; having; the movable part is placed on the outer end surface of the outer cylinder and is movably supported on the surface of the outer end surface; The alignment mechanism is characterized by this.

2. A locking member is further provided between the inner peripheral surface of the outer cylinder and the outer peripheral surface of the movable part, which locks the movable part to suppress the horizontal movement of the movable part. The inner peripheral surface and the outer peripheral surface each have a gradient surface of a plane that are arranged opposite to each other and are inclined so that the distance between them increases as they move away from the lens barrel. The locking member has a pair of inclined side surfaces corresponding to the gradient surfaces of the inner peripheral surface and the outer peripheral surface, enters between the gradient surfaces, and is sandwiched by bringing the inclined side surfaces into contact with the gradient surfaces to lock the movable part. The alignment mechanism according to claim 1, characterized by this.

3. A screw hole is formed in the outer cylinder, and a fixing member screwed into the screw hole is inserted into a through hole provided in the locking member and screwed into the screw hole. The alignment mechanism according to claim 2, characterized by this.

4. An inspection method for detecting fine dust adhering to the peripheral wall of the passage of an electron beam in an electron beam irradiation device including a lens barrel having an internal space in a vacuum state, an electron gun provided in the lens barrel for emitting an electron beam, an imaging device for imaging the electron beam, and an alignment mechanism for adjusting the arrangement by moving the electron gun in a plane perpendicular to the emission direction of the electron beam of the electron gun to adjust the emission axis of the electron beam of the electron gun, comprising: the alignment mechanism is: an outer cylinder erected at an opening of the lens barrel; a bellows disposed inside the outer cylinder, one end of which is fixed to the opening of the lens barrel and communicates with the internal space of the lens barrel; a movable part connected to the other end of the bellows, hermetically supporting the electron gun inside the bellows, placed on the outer end surface of the outer cylinder, and movably supported on the surface of the outer end surface. While emitting the electron beam in a vacuum state of the lens barrel and maintaining the state in which the electron beam is emitted, the alignment mechanism is used to move along the outer shape of the peripheral wall so that at least a part of the electron beam contacts the outer shape of the peripheral wall, and while the electron beam is being emitted, the imaging device is made to image the peripheral wall of the passage through which the electron beam passes. A inspection method characterized by the above.

5. The imaging device is arranged on the irradiation axis of the electron beam of the electron gun with the light receiving axis aligned so as to be able to image the irradiation shape of the electron beam. The electron beam is irradiated so as to contact the peripheral wall, and the projected shape of the peripheral wall is imaged by the imaging device as an outer shape that defines a part of the irradiation shape of the electron beam. The inspection method according to claim 4, characterized by the above.

Images