JP2681010B2 - Valve for vacuum device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve for a vacuum device for adjusting the pressure of gas introduced into a vacuum container to a pressure close to atmospheric pressure.

[0002]

2. Description of the Related Art Conventionally, in the process of manufacturing a semiconductor device, there are various processes in which a semiconductor substrate (hereinafter referred to as a wafer) is housed in a vacuum container and processed such as ion implantation and vacuum deposition. When the processing of the wafer is completed in such a process, before returning the vacuum container to the atmosphere, nitrogen gas or the like is introduced into the vacuum container to return it to the atmospheric pressure and then the wafer is taken out in order to prevent the wafer from being oxidized. Furthermore, to prevent atmospheric particles from entering the vacuum container when opening the door of the vacuum container,
The door was opened by making the inside of the vacuum container slightly higher than atmospheric pressure.

However, although this nitrogen gas is introduced to increase the pressure in the vacuum container and then return it to the atmosphere, the nitrogen gas is rapidly introduced by the sending pressure of the nitrogen gas supply device and is made of equipment such as glass or glass in the vacuum container. It may destroy things. Therefore, in order to prevent the pressure from rising too much, a vacuum device valve, which is a kind of relief valve, is usually provided between the gas supply device and the vacuum container. An example of this type of valve for a vacuum device is disclosed in Japanese Patent Application Laid-Open No. 11007979.

FIGS. 4 (a) and 4 (b) are enlarged views of a vacuum device and a portion A for explaining an example of a conventional vacuum device valve. As shown in FIG. 4A, the above-described vacuum device valve is attached to a connection pipe 23 that is connected to the pipe 20 between the leak valve 24 attached to the vacuum container 19 and the nitrogen gas cylinder 21.

As shown in FIG. 4 (b), the vacuum device valve encloses the hole 34 of the connection pipe 23 so as to surround the hole 34 and is fixed to the connection pipe 23.
A sphere 32 placed inside the housing 31 via an O-ring 33 around the hole 34, a spring 29 that applies a pressing force to the sphere 32, and a pressing plate 28 that compresses the spring 29. And a handle 26 for rotating the shaft portion that moves the pressing plate 28 by meshing the screw portion 27 of the housing 31 with the shaft portion.

In operation of the vacuum apparatus valve, first, the wafer is processed in the vacuum container 19 which is evacuated by the vacuum pump 25. Then, nitrogen gas is sent from the nitrogen gas cylinder 21, the leak valve 24, the pipe 20, and the connection pipe 23.
Fill up with. At this time, since the nitrogen gas cylinder 21 is filled with nitrogen gas at a pressure of about 2 atm, the leak valve 24, the pipe 20, and the connection pipe 23 temporarily rise to about 2 atm.

However, the high gas pressure in the hole 34 of the connecting pipe 23 resists the repulsive force of the spring 29 and causes the sphere 32 to move.
Push up. As a result, the O-ring 33 and the sphere 32
And a nitrogen gas leaks from this gap and is discharged to the outside of the housing 31 through the air hole 30. However, the leak valve 24, the connection pipe 23, and the pipe 20 are kept filled with nitrogen gas.

Next, the leak valve 24 is opened and nitrogen gas is introduced into the vacuum container 19. The nitrogen gas is continuously introduced until the pressure of the nitrogen gas introduced into the vacuum container 19 rises and reaches the pressing force of the sphere 32. When the nitrogen gas is discharged and the gas pressure falls below the pressing force of the spring 29, the sphere 32
Presses the O-ring 33 and hermetically closes the hole 34.

As described above, since the gas introduced into the vacuum container 19 is introduced at a low pressure, the gas inside the vacuum container 19 or the glassware is not destroyed and the vacuum container 19 is kept at about atmospheric pressure. It was characterized by the ability to return to equal pressure.

[0010]

However, although the above-mentioned conventional valve for a vacuum device can return the inside of the vacuum container to the atmosphere without damaging the equipment inside the vacuum container, the pressure of the vacuum container is higher than the atmospheric pressure. Even if it is set slightly higher, a particle rising phenomenon occurs due to a flow of air in the vacuum container caused by a pressure difference when the door of the vacuum container is opened. Therefore, there is a problem that particles adhere to the processed wafer and cause serious defects in quality.

In the first place, in order to eliminate this particle rising phenomenon, ideally, the pressure difference between the internal pressure of the vacuum container and the atmosphere should be 0 kg / cm ² , but when this pressure difference disappears, the door is opened. When opened, particles enter the vacuum container from the outside and contaminate the wafer as described above. That is, the intrusion of particles into the vacuum container and the rising of the particles in the vacuum container, which occur when the door is opened, are caused by a slight difference in pressure difference between the inside and outside of the vacuum container.

In a trial, a valve for a vacuum device of this type was used to store a silicon wafer having a diameter of 5 inches in a vacuum container and the differential pressure thereof was set to 0.03 kg / cm ^2. A phenomenon occurred and particles of 0.3 μm or more adhered for 500 or more. Furthermore, when the pressure was set to the lowest differential pressure that could be adjusted with this type of vacuum device valve, and the operation was performed several times, there were cases where particles soared and cases where particles did not soar. In order to investigate this cause, the differential pressure was measured each time with a precision manometer, and it was found that the differential pressure varied even though the differential pressure was set. Then, it was found that particles did not soar at a low pressure of 0.023 kg / cm ² or less.

This is because, in the mechanism for mechanically compressing the spring and setting the differential pressure like the valve opening / closing mechanism of the valve for the vacuum device described above, there is rattling of screw feed and coarse resolution of the compression force setting resolution. Therefore, it is difficult to set a minute pressure such as 0.023 kg / cm ² . Therefore, although the container inside the vacuum container can be returned to the atmosphere without damaging the container, the particle rising phenomenon cannot be suppressed.

Therefore, an object of the present invention is to provide a valve for a vacuum device which can precisely set the gas pressure introduced into a vacuum container so as to have a minute pressure difference with respect to the atmospheric pressure.

[0015]

A first feature of the present invention is as follows.
A housing having a gas inflow port and a gas outflow port and having an opening in the middle of a flow path communicating with the inflow port and the outflow port; and a valve seat covering the opening and surrounding the opening are packed. A valve for a vacuum device, comprising: a valve body member that is pressed by its own weight through a valve body; and a plunger that presses the valve body member toward the opening side or separates from the valve body member. In addition, a weight adjusting member to be placed on the valve body member is provided if necessary. Further, it is desirable to provide a first solenoid coil that performs the pressing operation and the separating operation of the plunger by an electromagnetic force.

A second feature of the present invention is a second plunger which covers the opening and has one end in contact with the valve body member mounted on the valve seat through the packing, and the second plunger having the above-mentioned structure. It is a valve for a vacuum device provided with a second solenoid coil that applies a force for pressing a valve body member as an electromagnetic force, and a variable DC power supply that changes a current flowing through the second solenoid coil.

A third feature of the present invention is gas detection for detecting the gas flowing out from the opening blocked by the valve body member in the first vacuum device valve or the second vacuum device valve. It is equipped with a sensor.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIGS. 1A to 1C are sectional views showing the valve for a vacuum device according to the first embodiment of the present invention in the order of operation. As shown in FIG. 1, this vacuum device valve has a gas inflow port 5 and a gas outflow port 6, and also has a gas inflow port 5 and a gas outflow port 6.
Housing 4 having an opening 10 in the middle of a flow path communicating with
A valve body 1 that covers the opening 10 and presses the valve seat 11 around the opening with its own weight through the packing 9, and a valve body is pressed to the opening 10 side by the tip end to close the opening 10 airtightly or And a plunger 3 for separating the tips.

Further, as a mechanism for pressing and separating the plunger 4 against the valve body 1, a mechanism in which a solenoid coil 8 and a spring 7 combined by electromagnetic force are combined is suitable because it can be downsized. If this valve has a large diameter, it is preferable to use an air pressure type that can take a high operating pressure.

The setting of the pressure difference between the inside and the outside of the vacuum container in the valve for the vacuum device is determined by the weight of the valve body 1 although its operation will be described later. Therefore, if the weight adjusting member 2 is mounted on the valve body 1, various weight adjusting members 2 are prepared, and the valve body 1 is selected according to the pressure difference for each setting.
If you put it on the surface, a minute pressure difference of 0.001kg / cm ²
To a large differential pressure of about 0.03 kg / cm ² can be set in a wide range.

The packing 9 for hermetically sealing the pressing valve seat 11 with the valve body 1 must be made of a soft material unlike an ordinary O-ring. Rather, hollow O-rings or U-seals are suitable. This is because the differential pressure can be set in a wide range because it is necessary to crush the packing 9 with a small pressing force and airtightly close the opening 10.

Further, the rising position of the lower end of the plunger 3 on the upper side of the valve body 1 is such that when the valve body 1 floats up due to pressure, the valve seat 1
The gap between the lower end of the plunger 3 and the valve body 1 is set to, for example, 1 mm or less so as not to deviate from the position 1. Further, the diameter of the plunger 3 is substantially the same as the diameter of the valve body 1.

Next, the operation and action of this vacuum device valve will be described. First, as shown in FIG. 1 (c), the plunger 3
The valve body 1 is pressed against the valve seat 11 to hermetically seal the opening 10, and the vacuum container (not shown) is evacuated. Then, after evacuating and processing the wafer, as shown in FIG.
The plunger 3 is raised to separate the lower end from the valve body 1.
Here, it is assumed that the gas inlet 5 connected to the vacuum container is in a vacuum state with an absolute pressure of 0.001 [kg / cm ² ]. The pressing force of the valve body 1 against the valve seat 11 at this time is 1 [kg / cm ² ] × atmospheric pressure, where D is the area of the opening 10.
F that is obtained by adding the force F ₁ of D [cm ² ] and the own weight F _{2 of the} valve body 4
₁ + F ₂ = F ₃ [kg].

Then, a leak valve attached to a vacuum container (not shown) is opened, nitrogen gas is introduced into the vacuum container, and when the pressures of the vacuum container and the gas inlet 5 become atmospheric pressure, the balance of the force at this point is reached. Since F ₃ > F ₁ (atmospheric pressure × D = F ₁ ), the valve body 4 is pressed by the force of its own weight F ₂ .

Further, when the introduction of nitrogen gas progresses and the pressure in the vacuum container and the gas inlet 5 exceeds F ₂ / D over 1 atm, the valve body 1 floats above the valve seat 11 and is shown in FIG. 1 (b). As described above, the nitrogen gas from the gas inlet 5 receives the valve body 1 and the valve seat 1
1 is discharged to the atmosphere from the gas outlet 6.
In this state, the pressure in the vacuum container and the gas inlet 5 is maintained at F ₃ / D [kg / cm ² ] by releasing the nitrogen gas into the atmosphere unless the amount of nitrogen gas introduced is extremely large. become. That is, even if the leak valve is closed and gas introduction is stopped, the valve body 1 descends and the valve seat 1
1 and the opening 10 is hermetically sealed. The internal pressure of the vacuum container and the gas inlet 5 is 1 atm and F ₂ (valve 1
The pressure is equal to or less than the pressure applied by (weight of own) / D [kg / cm ² ].

That is, the pressure difference between the vacuum container and the outside air can be set by the valve for the vacuum device by the weight of the valve body 1. For example, assuming that the pressure difference at which the particles do not rise is 0.023 kg / cm ² , the weight and thickness of the valve body 1 when the pressure difference is set will be calculated. The diameter of the opening is 20 mm and the diameter of the stainless steel valve body 1 is 30 mm.

As a result, the area of the opening 10 is 1 × 1 × 3.
14 = 3.14 cm ² , and the force at the opening 10 is
A ^{23g / cm 2 × 3.14cm 2 =} 72.22g. That is, the weight of the valve body 1 is 72.22 g. The thickness of the valve body is 72.22 g / 7.8 (g / cm ² ) when the specific gravity of stainless steel is 7.8.
× 1.5 cm ² × 3.14 = 1.31 cm, about 1
3 mm. In addition, the thickness is set to about 8 mm and the remaining 5
mm The thickness of the plate thickness is 3.5 m as the weight adjusting member 2.
A lead plate having a thickness of m may be used.

When a vacuum device using this valve for a vacuum device was tried, the number of adhered particles of 0.3 mm or more on a φ5 ″ silicon wafer was 50 or less as compared with 500 or more in the prior art. Regarding the sealing property of the valve body 1, in the case of the conventional technique, the air / vacuum was repeated 100 times, and the sealing failure occurred 15 times, whereas it was 0.
The result was obtained.

FIG. 2 is a sectional view of a vacuum apparatus valve showing a second embodiment of the present invention. As shown in FIG. 2, this vacuum device valve is provided with a variable DC power supply unit 12 that varies the current flowing through the solenoid coil 8a, and by changing the current from the variable DC power supply unit 12, the valve body 1a of the flanger 3a is supplied. The pressing force is changing. Other than that, the housing 4 having the gas inlet 5 and the gas outlet 6 and the opening 10 is the same as that of the above-mentioned embodiment. Further, the packing 9 that hermetically seals the valve body 1a and the valve seat 11 is also the same as that in the above-mentioned embodiment.

The differential pressure setting operation of the vacuum device valve is different from the above-described embodiment in which the pressure difference is set by changing the weight of the valve element.
The pressing force of the valve body 1a is set by changing the electromagnetic force. That is, when the current flowing to the solenoid coil 8a is zero, the lower end of the plunger 3a is at the valve body 1a.
As the current to the solenoid coil 8a is increased, the plunger 3a is lowered against the repulsive force of the spring 7a to set the minimum current when the plunger 3a comes into contact with the valve body 1a, and thereafter the current increases. This is due to the increase in pressing force.

For example, considering the repulsive force of the spring 7a, the pressing force due to only the weight of the valve body 1a is set to 0.01 kg / cm ² at the minimum current flowing through the solenoid coil 8a, and the pressing force is set to 0. If you set it to 03 kg / cm ² ,
The differential pressure can be set in a wide range as in the above-described embodiment. Further, in this embodiment, it is possible to continuously change the weight of the valve body without changing the weight each time like the weight,
Moreover, it has the feature that it can be finely adjusted.

3 (a) and 3 (b) are a sectional view showing a vacuum apparatus valve of a third embodiment of the present invention and a view showing a vacuum apparatus using this vacuum apparatus valve. As shown in FIG. 3A, this vacuum device valve is provided with a flow sensor 13 for detecting the flow of gas flowing out from the opening 10 blocked by the valve body 1 of the vacuum device valve shown in FIG. That is.
The flow sensor 13 includes a tubular member 13c connected to the gas outlet 6, a float 13a inserted into the tubular member 13c, and a sensor 13b for detecting the presence or absence of gas flow by the movement of the float 13a. It is configured.

Next, FIG. 3 using this valve for a vacuum device
The operation of the vacuum device of (b) will be described. First, FIG. 3 (b)
After the vacuum container 19a is sufficiently evacuated by the vacuum pump 25a, the opening / closing valve 16 is closed and the opening / closing valve 15 is opened to introduce the nitrogen gas into the vacuum container 19a. When the pressure of the vacuum container 19a rises to the same pressure as the atmospheric pressure and further rises to reach the pressure before pushing up the valve body 1 of the vacuum device valve 17 of FIG. 3 (a), the nitrogen gas is blocked by the valve body 1. The float 13a, which rises due to the gas flowing from the opening 10 that is separated, is attached to the sensor 13
Detect with b.

The sensor 13b transfers to the nitrogen gas valve control unit 14 as a signal for confirming that the vacuum container 19a has reached the atmospheric pressure by this detection, and the nitrogen gas valve control unit 14 closes the opening / closing valve 15. A signal is sent and the on-off valve 15 is closed to stop the supply of nitrogen gas. The vacuum container 19a is completely returned to the atmosphere, and the door can be opened without particles rising.

In this embodiment, the flow sensor has been described as applied to the valve for the vacuum device of FIG. 2, but it can also be applied to the valve for the vacuum device of FIG. Further, this flow sensor is a sensor that detects when the float rises, but a smaller pressure difference can be detected by using a more precise flow sensor such as a mass flow meter.

[0037]

As described above, according to the present invention, the mechanism for setting the difference between the internal pressure and the external pressure of the vacuum container is provided by separating the valve body closing the opening through which the gas passes from the plunger and pressing it against the valve seat of this valve body. Since a mechanism that changes the weight of the valve disc or the electromagnetic force applied to the valve disc is used, the screw feed rattle and compression force can be set like the conventional screw feed mechanism that compresses with a spring to set the pressing force. The roughness of resolution is eliminated, and the pressure difference between the inside and the outside of the vacuum container can be set minutely and reproducibly and precisely. Further, by providing a gas detection sensor that detects gas leaking from the valve body pushed up by the pressure difference, the pressure difference can be set minutely.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a valve for a vacuum device according to a first embodiment of the present invention in operation order.

FIG. 2 is a cross-sectional view of a vacuum device valve showing a second embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a vacuum device valve of a third embodiment of the present invention and a diagram showing a vacuum device using the vacuum device valve.

FIG. 4 is an enlarged view showing a vacuum device and an A part for explaining an example of a conventional valve for a vacuum device.

[Explanation of symbols]

 1, 1a Valve body 2 Weight adjusting member 3, 3a Plunger 4 Housing 5 Gas inlet 6 Gas outlet 7 7a, 29 Spring 8, 8a Solenoid coil 9 Packing 10 Opening 11 Valve seat 12 Variable DC power supply 13 Flow sensor 13a Float 13b Sensor 13c Cylindrical member 14 Nitrogen gas valve control unit 15, 16 Open / close valve 17 Vacuum device valve 19, 19a Vacuum container 20 Pipe 21 Nitrogen gas cylinder 23 Connection pipe 24 Releasing valve 25, 25a Vacuum pump 26 Handle 27 Screw part 28 Pressing Plate 29 Opening / Closing Mechanism 23 Connection Pipe 24 Opening / Closing Handle 25 Vacuum Pump 26 Adjusting Handle 27 Screw Part 28 Pressing Plate 30 Air Hole 31 Housing 32 Sphere 33 O Ring 34 Hole 34 Opening

Claims (5)

(57) [Claims] 1. A housing having a gas inflow port and a gas outflow port and having an opening in the middle of a flow path communicating with the inflow port and the outflow port; and a housing covering the opening and surrounding the opening. A valve for a vacuum device, comprising: a valve body member that presses a valve seat with its own weight through packing; and a plunger that presses the valve body member toward the opening side or separates from the valve body member. 2. The valve for a vacuum device according to claim 1, further comprising a weight adjusting member mounted on the valve body member. 3. The valve for a vacuum device according to claim 1, further comprising a first solenoid coil that performs the pressing operation and the separating operation of the plunger by an electromagnetic force. 4. A second plunger, one end of which contacts the valve body member according to claim 1, which covers the opening and is mounted on the valve seat through the packing, and the second plunger is provided with the valve. A valve for a vacuum device, comprising: a second solenoid coil that applies a force for pressing a body member as an electromagnetic force; and a variable DC power supply that changes a current flowing through the second solenoid coil. 5. The valve for a vacuum device according to claim 1, further comprising a gas detection sensor that detects the gas flowing out from the opening closed by the valve body member.