JPH0842734A - Main valve - Google Patents

Abstract

PURPOSE:To stop a valve body steplessly in an optional position by providing the valve body larger than an exhaust port for opening and closing an opening part, connecting mutually opposed electric cylinders to the valve body, respectively, and providing a driving source for driving the electromagnetic cylinders, respectively. CONSTITUTION:Tow electric cylinders 10a, 10b are set around the exhaust port 5 of a vacuum chamber 4 opposite to each other, the vertically moving rods 17 of the electric cylinders 10a, 10b are protruded into the vacuum chamber 4. A disc valve body 2 larger than the exhaust port 5 to open and close the opening part through a plate 24 is fixed to the top ends of the rods 17. The electric cylinders 10a, 10b are connected to the valve body 2, the lower ends of ball screws 12 protruded from the bottom surfaces of the electric cylinders 10a, 10b are connected to each other through the shaft 34 and coupling 35 of a stepping motor 11, and the rotating motion of the stepping motor 11 is converted into a linear movement by the ball screws 12 so that the valve body 2 can be vertically moved and stopped steplessly at an optional position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a main valve installed at an opening where a vacuum chamber is connected to a main exhaust pump, that is, at an exhaust port. In particular, the invention is
The present invention relates to a main valve capable of finely controlling exhaust conductance.

[0002]

2. Description of the Related Art In a vacuum processing apparatus such as a sputtering apparatus, a dry etching apparatus or a plasma CVD apparatus, various gases (hereinafter referred to as "process gas"), such as argon gas for discharge, are used for surface treatment of a substrate. It is introduced into the vacuum chamber, and the pressure of the process gas in the vacuum chamber is adjusted so that the surface treatment of the substrate is properly performed. As a method of adjusting the pressure of the process gas, (a) a method of adjusting the flow rate of the introduced gas,
(B) A method of adjusting the conductance of a variable orifice (that is, a conductance adjusting mechanism) installed between the main valve of the vacuum chamber and the main exhaust pump, (c) an open position and a closed position of the valve element of the main valve with an air cylinder. A method of gradually stopping between positions is known.

A bridge-type main valve is generally widely used as a conventional main valve installed at an exhaust port 5 to which a vacuum chamber 4 and a main exhaust pump 3 are connected. In this bridge type main valve, as shown in FIG. 1, the main valve is provided at the upper end of the rods 14 of the two air cylinders 1a and 1b that are arranged to face each other near the exhaust port 5 provided at the bottom of the vacuum chamber 4. Valve body 2 is connected. By moving the rods 14 of the air cylinders 1a and 1b in the vertical direction, the valve body 2 is moved in the vertical direction (arrow 4).
Move to 8). During evacuation of the vacuum chamber 4,
The valve body 2 is set to the open position 7. Further, the valve body 2 is set to the closed position 6 while the vacuum exhaust is stopped. In FIG. 1, a variable orifice 8 is provided between the exhaust port 5 and the main exhaust pump 3. By adjusting the opening degree of the variable orifice 8, the conductance of exhaust of the process gas can be controlled. Therefore, the pressure of the process gas in the vacuum chamber 4 is adjusted by controlling the conductance.

When the main valve is not provided with the variable orifice 8, the pressure in the vacuum chamber must be adjusted only by adjusting the flow rate of the process gas. Therefore, when the pressure in the vacuum chamber is lower than the desired pressure, a process gas flow rate that exceeds the exhaust capacity of the main exhaust pump is required, but there is a problem that the desired pressure cannot be obtained due to insufficient process gas flow rate. .

This problem can be largely solved when the pressure is adjusted by the variable orifice 8. However, even if the opening degree of the variable orifice 8 is fully opened, the main exhaust pump 3 can be operated due to the inherent conductance of the orifice.
However, there is a problem that the maximum pumping speed is sacrificed (decreased).

The rod 14 of the air cylinders 1a, 1b
Operate rapidly with compressed air. The valve body 2 connected to the rod 14 also rapidly moves from the open position 7 to the closed position 6. By such an operation of the valve body 2, a quick evacuation operation and a quick shutoff can be easily performed. However, since the rod 14 is operated by the compressed air, the valve body 2 can be stopped only in the open position 7 and the closed position 6.

FIG. 2 shows a main valve having a stepwise stop mechanism in which the valve body 2 can be stopped at a closed position 6, an open position 7 and a stepwise stop position 9. In this stepwise stop mechanism, a plurality of spacers 40 are attached to the tips of the rods 14 protruding from the air cylinders 1a, 1b. By removing one or more spacers, the opening degree of the valve body 2 can be stopped stepwise. The conductance of exhaust gas can be adjusted by gradually stopping the valve body 2.

However, since the stop position 9 of the valve body 2 is adjusted stepwise by removing the spacer, the conductance of exhaust cannot be finely adjusted, so that the pressure of the process gas in the vacuum chamber can be finely adjusted. It will not be possible. For example, in the reactive sputtering method in which the composition ratio of the film is sensitively changed by the flow rate ratio (partial pressure ratio) of a plurality of process gases, when the pressure in the vacuum chamber is controlled by this stepwise stop mechanism, a thin film having a desired composition ratio is obtained. There is a problem that can not be obtained.

[0009]

As described above, in the conventional bridge type main valve, when the pressure is adjusted by the variable orifice provided between the main valve and the main exhaust pump, there is a problem that the exhaust speed is lowered. In addition, there is a problem that it is difficult to finely adjust the conductance of exhaust gas with a mechanism that stops the valve element in stages.

An object of the present invention is to solve these problems and to provide a bridge type main valve that stops the stop position of the valve body at an arbitrary position steplessly. According to the present invention, it is possible to finely adjust the pressure of the process gas in the vacuum chamber without the variable orifice.

[0011]

In order to achieve the above object, the main valve of the present invention is a main valve installed in a connection opening between a vacuum chamber and a main exhaust pump, for opening and closing the opening. It has a valve element that is larger than the opening, an electric cylinder connected to the valve element that faces each other, and a drive source that drives the electric cylinder.

The chamber formed by the cylinder and the piston of the electric cylinder is provided with a port for injecting a pressurized fluid for moving the valve body in the direction of closing the opening.

The electric cylinder includes a ball screw connected to a drive source in the cylinder, a nut screwed with the ball screw, a piston joined to the nut, and a rod having the piston formed at its tip. And the rod penetrates the bellows and is connected to the valve body.

In order to achieve the above object, the main valve of another invention is such that one end of the valve body larger than the opening is connected to the wall surface of the vacuum chamber so that the valve body can rotate, and the other end of the valve body. The rod of the electric cylinder that penetrates the bellows is connected to. Further, the electric cylinder includes a ball screw connected to a drive source in the cylinder, a nut coupled to the ball screw, a stopper for stopping rotation of the nut, a piston joined to the nut, and the piston. Has a rod formed at the tip. An inlet for pressurized fluid is provided in the chamber formed by the cylinder and the piston so that the valve body moves in the direction of closing the opening.

[0015]

According to the main valve of the present invention, the valve body can be stopped at any position between the open position where the exhaust port is fully opened and the closed position where the exhaust port is completely closed. The conductance of the exhaust port is adjusted by adjusting the stop position of the valve element. By adjusting the conductance of the exhaust port,
The pressure of the process gas in the vacuum chamber can be finely adjusted. Also, setting the valve body to the open position
The main exhaust pump exhibits the maximum exhaust speed, and therefore, fine pressure adjustment can be performed without sacrificing the maximum exhaust speed of the main exhaust pump. Furthermore, a desired vacuum state can be obtained even when the vacuum processing state depends on the gas flow rate to be introduced.

Further, in order to speed up the operation of the valve body closing the exhaust port, the operation of the piston connected to the valve body is speeded up by injecting the pressurized fluid into the cylinder. It is possible to shut off the exhaust port suddenly and respond to situations such as emergency stop and power failure.

[0017]

Embodiment 1 The present invention will be described below based on embodiments.

FIG. 3 is a sectional view of the bridge type main valve of the preferred embodiment. A circular exhaust port 5 is formed on the bottom wall of the vacuum chamber 4 of the vacuum processing apparatus. The main exhaust pump 3 is connected to the outside of the exhaust port 5. Two electric cylinders 10a, 10 facing each other around the exhaust port 5
b is installed. A rod 17 which moves up and down of the electric cylinders 10a and 10b extends in the vacuum chamber 4. The portion of the wall surface to which the rod 17 is attached is sealed with a bellows 15 as shown in FIG. The seal by the bellows 15 separates the inside of the vacuum chamber 4 from the atmosphere side even if the rod 17 moves up and down. A disc-shaped valve body 2 larger than the exhaust port 5 is fixed to the tip of the rod 17 via a plate 24. A groove 30 is formed in a portion of the lower surface 2a of the valve body 2 that faces the peripheral portion of the exhaust port 5. An O-ring 31 is fitted in this groove 30. When the valve body 2 closes the exhaust port 5, the O-ring 31 seals between the peripheral wall surface of the exhaust port 5 and the valve body 2, so that the inside of the vacuum chamber 4 can be kept airtight.

FIG. 4 is a detailed sectional view of the electric cylinder. In FIG. 4, only the same electric cylinder 10a as the electric cylinder 10b is shown. The rod 17 of the electric cylinder 10a moves linearly or vertically in the vacuum container. Within the stroke of the rod 17, the rod 17 can be stopped at any position. It is possible to arrange three or more electric cylinders 10a around the exhaust port 5, but if two electric cylinders 10a are provided as in this embodiment, the entire main valve can be simplified and the rod of the electric cylinder can be used. It is easy to synchronize 17 operations.

The piston 18 formed at the lower end of the rod 17 is fitted in the cylinder 19 of each of the electric cylinders 10a and 10b. A chamber 23 formed by the cylinder 19 and the piston 18 is provided with an inlet 16 for pressurized air. The nut 13 is joined to the lower surface of the piston 18.
The nut 13 is screwed onto the thread portion of the ball screw 12. Part 1 of the ball screw 12 protruding from the nut 13
2 a penetrates the piston 18 and is housed in a hole 33 formed inside the rod 17. On the other hand, the cylinder 19
The lower end of the ball screw 12 having a bottom surface is connected to the shaft 34 of the stepping motor 11 via a coupling 35. The stepping motor 11 is "UPK-569" manufactured by Oriental Motor. The stepping motor 11 is fixed to the cylinder 19 via a column 36. Since the ball screw 12 is fixed to the shaft 34 of the stepping motor 11, the ball screw 12 does not move forward or backward even if the shaft 34 rotates. The rotation of the shaft 34 of the stepping motor 11 causes the ball screw 12 to simply rotate. The boundary between the atmosphere and the vacuum is sealed with an O-ring.

The cylinder 19 is installed outside the hole 20 formed in the bottom wall of the vacuum chamber 4 via a cylinder 21. A bellows 15 for vacuum sealing is provided in the cylindrical body 21, and the rod 1 having a bottom surface of the cylindrical body 21 is provided.
7 is a plate 22 attached to the upper end of the bellows 15.
An O-ring 37 seals between the plate 22 and the rod 17, which penetrates through and penetrates into the vacuum chamber 4. A plate 2 perpendicular to the tip of the rod 17
4 is fixed, and the lower surface of the tip portion of the plate 24 is joined to the upper surface of the valve body 2.

The vertical movement of the valve body 2 of the main valve of the present invention converts the rotational movement of the stepping motor 11 as a drive source into a linear movement by the ball screw 12, and
This is done by transmitting this linear movement to the rod 17. Specifically, as the shaft 34 of the stepping motor 11 rotates, the fixed ball screw 12 rotates. The rotation of the ball screw 12 causes the nut 13 to move upward or downward because the ball screw 12 is fixed. The piston 18 connected to the nut 13 moves upward or downward. The movement of the piston 18 causes the rod 17 to move upward or downward while the bellows 15 expands and contracts. By the vertical movement of the rod 17, the valve body 2 connected to the rod 17 moves upward or downward. In this way, the rotation of the ball screw 12 is controlled by the stepping motor 1
Since it can be finely controlled by 1, the valve body 2 can be stopped at an arbitrary position within the stroke of the rod 17. The stop position of the valve body 2 is changed to change the conductance of the exhaust port 5. Therefore, the conductance of the exhaust port 5 can be finely changed to adjust the pressure of the vacuum chamber 4.

When the main valve is used to quickly shut off the exhaust port, the stepping motor 11 is switched off and pressurized air is injected into the chamber 23 through the port 16. The injection of the pressurized air causes the piston 18 to receive pressure in the direction of the arrow 25 and rapidly move downward. And the piston 18
The valve body 2 rapidly moves downward via the rod 17 and the rod 17 connected to the valve body 17, and the valve body 2 closes the exhaust port 5. On the other hand, when the piston 18 moves downward, the nut 13 moves downward. When the nut 13 moves downward, the ball screw 12 and the stepping motor 11 run idle.

By moving the valve body 2 downward quickly as described above, it is possible to prevent the main pump 3 from being damaged due to an unexpected accident. For example, due to an unexpected accident,
When the pressure in the vacuum chamber 4 suddenly and abnormally rises (e.g., reaches atmospheric pressure), the high vacuum pump such as the molecular turbo pump or the cryopump used in the main pump 3 easily fails. This is because the high vacuum pump fails due to exposure to atmospheric pressure. By quickly closing the exhaust port 5 with the valve body 2, it is possible to prevent the high vacuum pump from being exposed to the atmospheric pressure and protect these pumps.

In the above embodiment, the control circuit for synchronously rotating the stepping motor 11 when driving the two electric cylinders, the sensor for confirming the position of the valve body 2, and the rotation of the stepping motor 11 are detected. An encoder (not shown) is provided in the main valve of this embodiment, although not shown.

When the two electric cylinders are driven, the rotational movement of the stepping motor 11, which is the rotational drive source of one electric cylinder, can be transmitted to the ball screw of the other electric cylinder by a rotation transmission mechanism such as a timing belt.

[0027]

[Embodiment 2] FIG. 5 shows a main valve in which a valve body 2 is moved by one electric cylinder. At one end of the plate 24 attached to the upper surface of the valve body 2, the rod 17 is inserted into a hole 44 formed at the end of the plate 24. The rod 17 is attached by a pin 42 that passes through the slit 43 of the plate 24. The other end of the plate 24 is rotatably attached by a bracket 40 and a pin 41 installed near the exhaust port 5. When the rod 17 connected to one end of the plate 24 moves up and down, the valve body 2 moves to the pin 4 as shown by an arrow 45.
Since it rotates about 1, the movement of the valve body 2 causes
The conductance of the exhaust can be adjusted.

When the valve element 2 is moved by one electric cylinder as described above, the nut 13 or the rod 17 is so arranged that the rotational movement of the ball screw 12 is surely transmitted to the nut 13 and the rod 17 as a linear movement. The stopper 46 that prevents rotation is unwound. In this embodiment, a rod-shaped stopper 46 is attached to the nut 13. The stopper 46 is provided with a hole 4 formed on the bottom surface of the cylinder 19.
According to 7. Even if the nut 13 rotates, the stopper 46 hits the hole 47 to prevent the nut 13 from rotating. However, the bridge-type main valve equipped with two electric cylinders facing each other on the valve body has a nut 13
Nut 13 to stop rotation of rod (or rod 17)
Alternatively, it is not necessary to provide the rod 17 with a stopper. This is because the rotation of the nut 13 (rod 17) of one of the electric cylinders causes the rotation of the nut 13 of the other electric cylinder.
This is because the rotation of the (rod 17) cancels out the mutual rotational movement.

In the above embodiment, the bellows 15 is used to separate the vacuum chamber 4 from the atmosphere side. But O
It is also possible to seal the rod 17 with a ring. A stepping motor can also be used for the main valve of this embodiment. It is also possible to inject pressurized oil into the chamber 23 in the cylinder 19 instead of pressurized air.

[0030]

As described above, according to the present invention, it is possible to provide a main valve capable of finely adjusting the conductance without impairing the maximum exhaust speed of the main exhaust pump. Further, according to the present invention, there is an effect that the exhaust port can be quickly closed in the case of an unexpected accident.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a conventional bridge-type main valve having a variable orifice.

FIG. 2 is a configuration diagram of a bridge-type main valve having a conventional stepwise stop mechanism.

FIG. 3 is a configuration diagram of a preferred embodiment of the present invention.

FIG. 4 is a detailed sectional view of an electric cylinder according to a preferred embodiment of the present invention.

FIG. 5 is a sectional view of another preferred embodiment of the present invention.

[Explanation of symbols]

 1a, 1b Air cylinder 2 Valve body 3 Main exhaust pump 4 Vacuum chamber 5 Exhaust port 6 Closed position 7 Open position 8 Variable orifice 9 Stop position 10a, 10b Electric cylinder 11 Stepping motor 12 Ball screw 13 Nut 14 Rod 15 Bellows 16 Port 17 Rod 18 Piston 19 Cylinder 20 Hole 21 Cylindrical body 22 Plate 23 Chamber 24 Plate 33 Hole 34 Shaft 35 Coupling 36 Strut 37 O-ring 40 Spacer 41 Pin 43 Slit 44, 47 Hole 46 Stopper

Claims (4)

[Claims] 1. In a main valve installed in a connection opening of a vacuum chamber and a main exhaust pump, a valve body larger than an opening for opening and closing the connection opening and a valve body connected to the valve body face each other. A main valve having two electric cylinders and a drive source for driving the electric cylinders. 2. A chamber formed by a cylinder and a piston of the electric cylinder is provided with an inlet for pressurized fluid for moving the valve body in a direction of closing the opening. Main valve. 3. The electric cylinder has a ball screw connected to a drive source in the cylinder, a nut screwed with the ball screw, a piston joined to the nut, and the piston formed at the tip. The main valve according to claim 1 or 2, further comprising a rod that extends through the bellows and is connected to the valve body. 4. A main valve installed in a connection opening between a vacuum chamber and a main exhaust pump, the valve body being larger than the opening for opening and closing the opening, and one end of the valve body being a wall surface of the vacuum chamber. The valve body is rotatably connected, and further has one electric cylinder driven by a drive source. The electric cylinder has a ball screw connected to the drive source in the cylinder, and the ball screw. A nut that is fitted, a stopper that stops rotation of the nut, a piston connected to the nut, and a rod having the piston formed at its tip, and in a chamber formed by the cylinder and the piston, A main valve characterized in that a pressurizing fluid inlet is provided for moving the valve body in a direction to close the opening, and a rod penetrating a bellows is connected to the other end of the valve body.