JP7670770B2 - Vacuum Sealing Valve - Google Patents

Description

The present invention relates to a vacuum sealing valve that opens and closes an opening in a partition wall that separates a vacuum chamber.

Devices that have a vacuum chamber, such as electron microscopes, are provided with a partition wall to separate the inside of the vacuum chamber and a vacuum sealing valve to seal the opening in the partition wall.

For example, Patent Document 1 discloses a gate valve (vacuum sealing valve) that includes a valve body with an O-ring for airtightly sealing the opening, and a shaft member with the valve body at its tip. The opening and the opening abutment surface of the valve body are inclined relative to the direction of travel of the shaft, and when the shaft member is advanced, the inclined opening abutment surface of the valve body seals the opening at an angle.

Japanese Patent Application Publication No. 1-126483

However, in the above-mentioned Patent Document 1, the O-ring of the sealing material is dragged as it is crushed, and the O-ring is subjected to a great deal of friction. In a vacuum environment, there is no lubricant such as oil or grease, or moisture in the air, and therefore the friction causes great damage to the O-ring and shortens its lifespan.
The present invention has been made in consideration of the above problems, and provides a vacuum seal valve that opens and closes an opening while reducing the burden on a sealing material.

In order to solve the above problems, in one aspect of the present disclosure, a vacuum sealing valve is configured to include a valve body that seals/unseals an opening formed in a wall body, a shaft member that can move back and forth approximately parallel to the wall body, a link mechanism that displaceably connects the valve body and the shaft member to each other, and a roller that is disposed in front of the valve body and abuts against the front surface of the valve body as the shaft member moves back and forth, and converts the forward and backward movement of the shaft member into movement of the valve body toward the opening via the link mechanism, and the front surface of the valve body is configured to include an inclined surface that first abuts against the roller as the shaft member moves forward and guides the valve body to a position facing the opening, and an orthogonal surface perpendicular to the wall body that the roller then abuts against the inclined surface to press the valve body against the wall body in the orthogonal direction to the wall body.

With this configuration, the valve body that seals the opening moves to the opposing position by coming into contact with the roller, and then moves straight toward the opening to seal it. Because the valve body only moves in the pressing direction during sealing, sealing can be achieved without the sealing material of the valve body sliding on the sealing surface, reducing the burden on the sealing material.

In one embodiment, the link mechanism is two pairs of links arranged in parallel, and the two pairs of links are linked and connected to the valve body parallel to the wall body, and are configured to support the valve body rotatably while remaining parallel to the wall body. With this embodiment, the valve body rotates while remaining parallel to the wall body. Even when sealing, the valve body can be pressed while remaining parallel to the wall body without rotating, reducing the burden on the sealing material.

The above configuration provides a vacuum sealing valve that opens and closes an opening while reducing the burden on the sealing material.

1 is a schematic diagram of an electron microscope equipped with a vacuum sealing valve according to an embodiment of the present invention. FIG. FIG. 2 is a side view of the vacuum seal valve (some components are not shown for the purpose of illustration). FIG. 2 is a vertical cross-sectional view of the vacuum seal valve. FIG. 6A and 6B are explanatory diagrams showing the opening and closing process of the opening and closing mechanism, in which Fig. 6A shows the open state (unsealed state), and Fig. 6D shows the closed state (sealed state). Figs. 6B and 6C show the intermediate states of opening and closing.

(Electron microscope 100)
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present disclosure will now be described with reference to the accompanying drawings. Fig. 1 is a schematic diagram of an electron microscope 100 including a vacuum seal valve 1 according to an embodiment.

As shown in FIG. 1, the electron microscope 100 includes an electron gun 101, an electron beam control mechanism 102 including a lens mechanism for converging the electron beam EB emitted from the electron gun 101 onto a predetermined portion of the sample W and a scanning mechanism for scanning the electron beam EB, and a lens barrel 103 that houses the electron gun 101 and the electron beam control mechanism 102.

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 101, and displays a sample image based on this detection signal in synchronization with two-dimensional scanning of the electron beam EB on the sample W. The configuration of the present disclosure is not limited to application to the electron microscope 100, but is also suitable for a transmission electron microscope (TEM) that irradiates the sample W with an electron beam EB and magnifies and observes the electrons that have passed through it, an electric wire drawing device, an electron beam exposure device, and the like. Also, an ion gun may be used instead of the electron gun 101 to irradiate an ion beam.

The column 103 has therein an electron gun chamber 104 that houses the electron gun 101, a control mechanism chamber 105 that houses the electron beam control mechanism 102, and a partition wall 106 that separates them. The partition wall 106 has an opening 107 that connects the electron gun chamber 104 and the control mechanism chamber 105. Due to the characteristics of the electron microscope 100, the electron gun chamber 104 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 exhaust mechanism 108A. Similarly, the control mechanism chamber 105 is evacuated to a vacuum by a vacuum exhaust mechanism 108B.

The electron microscope 100 is equipped with a vacuum seal valve 1 as a mechanism for sealing/unsealing (hereinafter referred to as opening and closing) the opening 107. The vacuum seal valve 1 is supported by passing through a through hole 109 provided in the side wall 103a of the microscope tube 103, which is approximately perpendicular to the partition wall 106. Since it takes time to evacuate the electron microscope 100, when repairing the electron gun 101 or replacing the sample W, the vacuum seal valve 1 is used to maintain the electron gun chamber 104 or the control mechanism chamber 105 at a vacuum. In addition, when transporting the electron microscope 100, the opening 107 is sealed with the vacuum seal valve 1.

(Vacuum sealing valve 1)
The vacuum seal valve 1 will be described in detail with reference to Figures 2 to 4. Figure 2 is a perspective view of the vacuum seal valve 1. Figure 3 is a side view of the vacuum seal valve 1. Figure 4 is a vertical cross-sectional view of the vacuum seal valve 1. In Figure 3, some components are omitted for ease of explanation.

As shown in Figures 2 to 4, the vacuum sealing valve 1 is provided with an opening/closing mechanism 2 at the tip that opens and closes the opening 107. The opening/closing mechanism 2 is composed of a moving side mechanism 7 and a fixed side mechanism 8 that is fixed to the partition wall 106. The moving side mechanism 7 of the opening/closing mechanism 2 is connected to a bellows 4 via a connection mechanism 3, and the bellows 4 is connected to an actuator 6 via a fixed part 5.

The actuator 6 is the driving source of the vacuum sealing valve 1. When the actuator 6 moves back and forth approximately parallel to the partition wall 106, this movement is transmitted to the opening and closing mechanism 2, which converts the back and forth movement of the actuator 6 into a motion for opening and closing the opening 107, thereby opening and closing the opening 107.

In this embodiment, a double-acting air cylinder is used for the actuator 6. A retractable single-acting air cylinder may be used, and when the electron gun 101 is not in use, the cylinder is maintained in a forward position by the bias of a compression spring or the like to keep the opening/closing mechanism 2 in a closed position, and only when the electron gun 101 is in use, the cylinder is moved backwards by air pressure to open the opening/closing mechanism 2. The bias of the compression spring makes it easy to maintain the opening/closing mechanism 2 in a closed position. The actuator 6 is not limited to this, and any known driving mechanism may be used.

As shown in FIG. 4, the bellows 4 is arranged to cover the periphery of the transmission shaft 41 arranged inside. The transmission shaft 41 is connected to the actuator 6 via a connection shaft 42. An end of the bellows 4 is fixed to the surface of the fixed part 5, and the internal space of the bellows 4 communicates with the internal space 51 provided in the fixed part 5. In this communicated internal space, the transmission shaft 41 moves forward and backward integrally with the actuator 6. By using the bellows 4, the transmission shaft 41 can be moved forward and backward by obtaining power from the actuator 6 located outside the electron gun chamber 104 (atmospheric side) while maintaining the vacuum atmosphere of the electron gun chamber 104.

The transmission shaft 41 is connected to the main shaft 71 that constitutes the moving mechanism 7 of the opening/closing mechanism 2 via the connection mechanism 3, and the forward and backward movement of the actuator 6 is transmitted to the opening/closing mechanism 2 as they move together.

(Opening and closing mechanism 2)
The opening/closing mechanism 2 will be described in detail with reference to Figures 5 and 6. Figure 5 is a cross-sectional view of the opening/closing mechanism 2 in an open state.
As described above, the opening/closing mechanism 2 is composed of the fixed-side mechanism 8 fixed to the partition wall 106 and the movable-side mechanism 7 that moves in conjunction with the forward and backward movement of the actuator 6 .

The fixed side mechanism 8 includes a support member 81, a first upper roller 82, a second upper roller 83, and a lower roller 84. The movable side mechanism 7 includes a main shaft 71, an auxiliary member 72, a spring 73, two pairs of links 74, 74, a valve body 75, an O-ring 76, and a bolt 77.

The support members 81 are a pair of L-shaped brackets that face each other in a position that does not impede the movement of the electron beam EB or the moving mechanism 7, are fixed to the partition wall 106 on a horizontal plane, and rotatably support the first upper roller 82, the second upper roller 83, and the lower roller 84 on a vertical plane (see FIG. 2). For the sake of explanation, one of the support members 81 located on the front side of the paper is omitted in FIG. 3 and FIG. 6.

The first upper roller 82 and the second upper roller 83 are rotating bodies for preventing deformation of the main shaft 71, that is, for preventing the main shaft 71 from bending upward due to the reaction force generated by pressing the valve body 75 against the opening 107. They are arranged in parallel to the forward and backward movement direction of the main shaft 71, and their rotation axes are perpendicular to the forward and backward movement direction of the main shaft 71. Since they do not function as a conveyor to guide the forward and backward movement of the main shaft 71, it is preferable that they approach the main shaft 71 in the open state but do not come into contact with it.

The first upper roller 82 and the second upper roller 83 are arranged above the main shaft 71 in a position facing the opening 107 below with the main shaft 71 in between in the up-down direction. In addition, with respect to the forward and backward direction (front-to-back direction) of the main shaft 71, the second upper roller 83 is arranged at the tip side of the main shaft 71 and the first upper roller 82 is arranged at the base end side of the main shaft 71 with the opening 107 as the reference. By arranging the first upper roller 82 and the second upper roller 83 to sandwich the opening 107, deformation of the main shaft 71 can be stably and firmly suppressed.

The valve body 75 has a roughly rectangular parallelepiped shape and is linked and connected to the main shaft 71 by two pairs of links 74, 74. It moves up and down in accordance with the forward and backward movement of the main shaft 71, thereby directly opening and closing the opening 107. The two pairs of links 74, 74 are what is called a dual link mechanism, and face each other on both sides of the valve body 75, linking and connecting the valve body 75 to the main shaft 71. The two pairs of links 74, 74 of the same shape are connected to the valve body 75 in a horizontal state, with their axes horizontal and parallel to each other, and furthermore, the pairs of links 74 are arranged parallel to each other. Therefore, the valve body 75 is held by the two pairs of links 74, 74, and is supported so as to be rotatable up and down around the rotation axis of the links 74 while remaining in a horizontal state.

The spring 73 is an elastic body that biases the valve body 75 in a direction that maintains the valve body 75 in an open state. The forward bias of the spring 73 is converted to an upward bias by the links 74, 74, and in the open state, the valve body 75 is held apart from the partition wall 106.

The lower roller 84 is disposed in front of the valve body 75, facing the second upper roller 83 across the main shaft 71. When the main shaft 71 moves back and forth, the lower roller 84 comes into contact with the front surface of the valve body 75, moving the valve body 75 in the up-down direction.

The auxiliary member 72 is an auxiliary member for holding the spring 73, and is formed with a deep recess 72a for holding the spring 73. The auxiliary member 72 is disposed on the back surface of the valve body 75 and is fixed to the bottom surface of the main shaft 71 by bolts 77 so that the spring 73 can efficiently bias the valve body 75. It is also possible to have a configuration in which the spring 73 is held directly by the main shaft 71 without using the auxiliary member 72.

The O-ring 76 is a sealing member for airtightly sealing the opening 107. A dovetail groove 75a is provided in an annular shape on the underside of the valve body 75, and the O-ring 76 fits into this groove, thereby attaching it to the underside of the valve body 75.

The valve body 75 is connected to the link 74 at a thin-walled portion 75b with its side cut away so that there is no step between the valve body 75 and the link 74 and the link 74 is connected smoothly. This reduces the width of the moving mechanism 7.

The valve body 75 and the main shaft 71 are provided with through holes 75c and 71c, respectively, for passing the electron beam EB. When the opening/closing mechanism 2 is assembled, the through holes 75c and 71c are configured to communicate with each other. When the opening/closing mechanism 2 is in the open state, the arrangement is adjusted so that the opening 107 and the through holes 75c and 71c are aligned in a straight line in the vertical direction. This ensures a path for the electron beam EB.

Of course, the valve body 75 and the main shaft 71 are made of non-magnetic material so as not to adversely affect the electron beam EB. By providing holes in the valve body 75 and the main shaft 71 that serve as a path for the electron beam EB, the valve body 75 can be positioned above the opening 107 even in the open state, reducing the amount of forward and backward movement of the main shaft 71 required to open and close the opening 107, minimizing the generation of particles due to metal sliding.

(Valve disc movement)
The shape and movement of the valve body 75 will be described in detail with reference to the drawings. FIG. 6 shows the process in which the opening 107 is opened and closed by the opening/closing mechanism 2 by the movement of the valve body 75 accompanying the forward movement of the main shaft 71. The black arrow in FIG. 6 indicates the movement direction of the main shaft 71, and the white arrow indicates the movement direction of the valve body 75. FIG. 6(A) shows the open state of the opening/closing mechanism 2. FIG. 6(D) shows the closed state of the opening/closing mechanism 2. FIG. 6(B) and FIG. 6(C) show the intermediate state of opening and closing. In FIG. 6, the main shaft 71 is disposed between the upper rollers 82, 83 and the lower roller 84 as an ideal state, and moves forward as it is. In reality, the main shaft 71 moves forward while in contact with the lower roller 84 due to its own weight, and after the valve body 75 abuts against the partition wall 106, the main shaft 71 bends upward due to the reaction force of the pressure and comes into contact with the upper rollers 82, 83.

The front surface of the valve body 75 is formed with an inclined surface 75d that is inclined downward from the horizontal state, and a vertical surface 75e that continues from the upper end of the inclined surface 75d. When the main shaft 71 moves forward, the lower roller 84 first abuts against the inclined surface 75d and then against the vertical surface 75e, moving the valve body in the vertical direction. Since the valve body 75 moves along the shape of the abutment surface while abutting against the lower roller 84, the movement of the valve body 75 depends on the shape of the front surface, which is the abutment surface of the valve body 75.

The movement of the valve body 75 will be described in detail using Figure 6. As shown in Figure 6 (A), when the opening/closing mechanism 2 is in the open state, the forward bias of the spring 73 is converted upward by the links 74, 74, and the valve body 75 is biased upward and held in a spaced apart state from the partition wall 106. In the open state, the valve body 75 is held horizontally parallel to the partition wall 106 by the links 74, 74.

When the main shaft 71 is advanced to seal the opening 107 from the open state of the opening/closing mechanism 2, the valve body 75 also advances together with the main shaft 71, and the inclined surface 75d on the front side of the valve body 75 abuts against the lower roller 84 (see FIG. 6(B)).

After the valve body 75 comes into contact with the lower roller 84, when the main shaft 71 is moved forward, the valve body 75 moves in the gradient direction of the inclined surface 75d while being held by the links 74, 74. The inclined surface 75d is an inclined surface that slopes downward as it approaches the front, and the valve body 75 moves diagonally forward and downward along the inclined surface 75d. The valve body 75 is held by two pairs of links 74, 74 and moves diagonally downward and forward while maintaining a horizontal state (see Figure 6 (C)).

When the main shaft 71 is further advanced, the valve body 75 moves forward and downward along the gradient of the inclined surface 75d while remaining in contact with the lower roller 84, and the vertical surface 75e then comes into contact with the lower roller 84. At this time, the O-ring 76, which is placed on the bottom surface of the valve body 75, is positioned directly above the opening 107 and close to the partition wall 106. When viewed from above, the opening 107 is located approximately in the center of the inside of the O-ring 76.

The valve body 75 moves along the gradient of the contact surface with the lower roller 84, so as the main shaft 71 advances, the valve body 75 now moves vertically downward. The valve body 75 moves straight down, and the O-ring 76 attached to the bottom surface of the valve body 75 presses against the partition wall 106, sealing the opening 107 (see FIG. 6 (D)).

As shown in FIG. 6, the partition wall 106 around the opening 107 has a slightly higher step 106a formed. This is to reduce the possibility of particles falling into the sealed area even if they are generated by the sliding of metal parts due to the movement of the opening/closing mechanism 2. Furthermore, particles that fall from the step 106a are less likely to climb back up onto the step 106a, i.e., the sealed area, so a decrease in sealing performance can be suppressed.

(Action and Effect)
If the O-ring 76 moves in the sealing pressing direction (vertical direction in this embodiment) of the valve body 75 and also in other directions from when it comes into contact with the sealing surface until it completely seals, the O-ring 76 will slide against the partition wall 106, which is the sealing surface. In a high vacuum atmosphere, no sliding force works, and a large load is applied to the O-ring 76 due to twisting and high friction sliding. In order to reduce damage to the O-ring 76 and improve the durability of the O-ring 76, an inclined surface 75d and a vertical surface 75e are formed on the front surface of the valve body 75 so that the O-ring 76 moves only in the vertical direction, which is the sealing pressing direction, from when it comes into contact with the partition wall 106 until it completely seals. The valve body 75 first comes into contact with the lower roller 84 with the inclined surface 75d, and is guided and moves along the inclined surface 75d so as to face the opening 107, and then the vertical surface 75e comes into contact with the lower roller 84, and the valve body 75 presses the opening 107 to seal the opening with the O-ring 76. In this embodiment, the partition wall 106 is provided horizontally, and the seal pressing direction is a vertical direction perpendicular to the partition wall 106. When the valve body 75 is disposed to face the opening 107 so as to cover it, it then moves only in the vertical direction perpendicular to the partition wall 106.

However, it is not limited to this, and even if the partition wall 106 is an inclined surface or a vertical surface, the main shaft 71 may move back and forth parallel to the partition wall 106, and the front surface of the valve body 75 may have an inclined surface in a direction that directs the valve body 75 to a position facing the opening 107 provided in the partition wall 106, and an orthogonal surface perpendicular to the partition wall 106. As a result, the inclined surface first contacts the lower roller 84, the valve body 75 moves toward the partition wall 106, the sealing material provided on the valve body 75 is positioned opposite the opening 107, and then the orthogonal surface contacts the lower roller 84, and the valve body 75 moves in the seal pressing direction. The sealing material can be moved only in the pressing direction without sliding on the sealing surface. Even if the partition wall 106 is a vertical surface or an inclined surface, the opening 107 provided in the partition wall 106 can be sealed with the sealing material perpendicular to the partition wall 106, regardless of the gradient of the partition wall 106. The O-ring 76 can be sealed without sliding against the partition wall 106, reducing the burden on the O-ring 76, which is a sealing material.

The above configuration allows the valve body 75 to move in two stages, so the amount of movement of the main shaft 71 in the forward and backward directions to open and close the opening 107 is small, and metal sliding can be reduced accordingly, making it possible to suppress the generation of particles. Because the valve body 75 abuts against the rollers of the rotating body, there is less metal sliding and the generation of particles can be further suppressed. Compared to when the front surface of the valve body 75 is composed only of a vertical surface, the fluctuation in the load direction and the movement of the valve body 75 are smoother, and the friction between the metals is less, making it possible to suppress the generation of particles accordingly.

When the forward motion of the main shaft 71 is converted by the lower roller 84 into downward movement of the valve body 75, the valve body 75 also moves downward. When the O-ring 76 presses against the partition wall 106, the O-ring 76 receives an upward reaction force from the partition wall 106. This reaction force causes the main shaft 71 to warp upward, but the first upper roller 82 and second upper roller 83 arranged above the main shaft 71 abut against the main shaft 71, suppressing deformation of the main shaft 71. This force is efficient and the valve body 75 can be sealed airtight.

Also, since the valve body 75 is supported by two pairs of links 74, 74, the valve body 75 rotates vertically around the axis of the links while maintaining a horizontal state. For example, if the valve body 75 is tilted from the horizontal state, it cannot seal the opening 107 evenly. As an example, in this embodiment, if the main shaft 71 is tilted 1.2 degrees vertically around the forward/backward direction (horizontal axis), the height difference due to the tilt is 0.2 mm on the opening 107. Also, the amount of crushing of the seal material sealing the opening 107 is about 0.5 mm, and the effect of the reduction in the amount of seal crushing due to the tilt of the valve body 75 from the horizontal state is large. To seal the opening 107 airtightly, the valve body 75 to which the O-ring 76 is attached needs to seal the opening 107 horizontally.

In this embodiment, the valve body 75 is supported by two pairs of links 74, 74 so that it can rotate while remaining horizontal, and therefore maintains its horizontal state even when the valve body 75 moves, and the O-ring 76 seals the opening 107 evenly while remaining horizontal when opening and closing. The two pairs of links 74, 74 are used as a link mechanism to support the valve body 75 so that it can rotate while remaining horizontal, and to uniformly seal the opening 107 airtightly. In addition, the surface of the partition wall 106 around the opening 107, which serves as the sealing surface for the O-ring 76, is also mirror-finished to improve sealing performance.

To replace the O-ring 76, the moving mechanism 7 must be removed from the microscope barrel 103. The electron microscope 100 cannot be used while the moving mechanism 7 is removed and the O-ring 76 is being replaced. By reducing the burden on the O-ring 76 and extending its lifespan, it is possible to extend the replacement period for the O-ring 76 and reduce the period during which the electron microscope 100 is not in use.

The above describes the preferred embodiment of the present invention, but modifications are possible based on the knowledge of those skilled in the art, and such modifications are within the scope of the present invention.

1: Vacuum seal valve 71: Main shaft (shaft member)
74: Link 75: Valve body 75d: Inclined surface 75e: Vertical surface (orthogonal surface)
84: Lower roller (roller)
106: Partition wall (wall)
107: Opening

Claims (2)

a valve body for sealing/unsealing an opening formed in the wall body;
A shaft member that is movable back and forth substantially parallel to the wall body;
a link mechanism that displaceably connects the valve body and the shaft member to each other;
a roller that is disposed in front of the valve body and comes into contact with a front surface of the valve body as the shaft member moves back and forth, thereby converting the forward and backward movement of the shaft member into movement of the valve body toward the opening via the link mechanism;
Equipped with
The valve body has a front surface which is first brought into contact with the roller by the forward movement of the shaft member to guide the valve body to a position facing the opening, and a perpendicular surface which is perpendicular to the wall body and which the roller then comes into contact with the inclined surface to press the valve body against the wall body in a direction perpendicular to the wall body.
A vacuum seal valve characterized by: The link mechanism includes two pairs of links arranged in parallel,
The two pairs of links are linked and connected to the valve body in a parallel state with the wall body, and support the valve body rotatably while keeping the valve body parallel to the wall body.
2. The vacuum seal valve according to claim 1.