WO2008023499A1 - Vacuum valve - Google Patents

Abstract

A pendulum type pressure control valve is improved such that an O-ring is protected by preventing contact with process gas, contamination in a vacuum process chamber due to fine particles generated from the O-ring and vacuum grease is prevented, and adverse effects caused by them on a product are controlled. In order to intercept the atmosphere in the vacuum process chamber from fine particles generated from O-rings (10, 11) provided, respectively, to the sliding surface of a shaft (14) for operating a seal ring (8) and to the sliding surface between the wall surface of a channel and the seal ring (8) and from vacuum grease used on each sliding surface when process gas is used, annular protection bands (12, 13) consisting of two corrosion resistant materials are arranged at positions holding the O-rings between them on the outer wall surfaces of the wall surface of a frame and the seal ring.

Description

 Specification

 Vacuum

 Technical field

 [0001] The present invention relates to a novel high-durability and high-performance vacuum valve in which a defect in a so-called pendulum type pressure control valve is improved.

 Background art

 In manufacturing semiconductor devices, there are many processes that require processing steps in a vacuum process chamber, such as chemical vapor deposition (CVD), plasma etching, and sputtering. In this process, different gas atmospheres must be created for each processing purpose. At this time, a vacuum valve is used to control the set pressure in the vacuum process chamber to be constant. Is required.

[0003] By the way, as one type of this vacuum valve, a circular slide plate is pivotally supported on a part of a frame body having a thick annular body force whose central portion is formed in a circular fluid passage. A so-called pendulum pressure control valve is known in which a slide plate is moved from side to side by a pendulum to cause a closed state from an open state. The pendulum pressure control valve requires a mechanism that adjusts the conductance of the valve by a small amount of movement of the circular slide plate to keep the pressure in the process chamber at a preset constant pressure. At this time, the flow rate of the reaction gas flowing into the process chamber is constant. When the vacuum process chamber and the vacuum pump are completely shut off, a seal ring that is close to or away from the circular slide plate is disposed when the circular slide plate is closed, and the annular surface that is close to the seal ring of the frame body is disposed. A plurality of holes having an axis parallel to the flow path axis are formed, and the seal ring is provided with a plurality of concave portions having a length in the circumferential direction at a predetermined interval on the side opposite to the slide plate. The opening of the recess is formed at the end of the keyhole-shaped opening, corresponding to a plurality of holes drilled in the annular surface of the frame, and having a head enlarged in the upper recess in the hole The pressure control bar is structured so that the O-ring attached between the circular slide plate and the seal ring is pressed by the shaft to completely shut it off. Lub (JP9-178000A), a wall with a fluid flow path and a valve seat, and a valve plate that is pressed against the valve seat in the closed state, and pressed against the valve plate or valve seat when closed. Vacuum nozzle C1P2 002 with an elastic seal ring that seals the fluid flow path, and a plastic ring that is placed closer to the opening than the seal ring when the vacuum valve is closed and relieves the pressing force acting on the seal ring — 228043A), a fluid flow path, a slide plate that can move between the closed position and the open position, and a seal ring force that surrounds the fluid flow path and acts on the slide plate in the closed position. Has a plurality of holes and a recess on the adjacent surface of the frame corresponding to the hole, and connects the hole in the seal ring and the recess in the frame. A vacuum valve (US6 863256B) provided with a fastener and rotated to engage the valve body, a valve body having a flow path, and first and second surfaces, and the flow path open state The control slide valve has a valve plate that moves between the closed state and the closed state, and the movement path forms the control region of the valve, and the valve plate protrudes from this surface to the valve plate. It has a contact ring supported by a spring, and in the closed state, this contact ring is pressed against the valve plate against the biasing force of the spring and comes into contact with the contact surface of the valve body beyond the surrounding surface. /! Things (JP2005-96 78A) have been proposed!

[0004] By the way, a slide plate that rotates in a direction perpendicular to the flow path axis between a frame having a fluid flow path and a closed position that prevents the flow of the fluid flow path and an open position that allows the flow. In the pendulum type pressure control valve composed of a seal ring that is in contact with the slide plate to form a completely closed state or is spaced apart to form a partially closed state when in the closed position, Actuate the seal ring between the flow path wall surface and the seal ring formed on the opposite side of the seal ring facing the slide plate for the purpose of completely closing the space between the vacuum process chamber and the vacuum pump. An O-ring, which is an elastic material force, is attached between the outer peripheral wall of the shaft and the inner wall surface of the insertion hole of the shaft drilled in the frame (for example, US5577707B).

[0005] However, since these O-rings are inserted in a state exposed to the process gas, fine particles generated by contact with the process gas are mixed in the process chamber, Contamination of the product and damage to the o-ring. Although there is a way to extend the life by using an expensive special o-ring for this failure, it still reduces the amount of fine particles that are generated but does not eliminate the contamination of the product. Also

Since these o-rings are used for sliding parts, it is necessary to apply a small amount of vacuum grease to the o-ring surface and sliding surface. In actual conditions, to avoid production costs, avoid using expensive special o-rings, and apply a larger amount of vacuum grease on the surface of cheap o-rings to reduce contact with process gas. The service life is extended by this. However, this vacuum grease is also a major factor in contaminating products in the process chamber due to the generation of fine particles due to contact with the process gas. I haven't found a way to completely prevent these problems!

 Disclosure of the invention

 [0006] The present invention relates to an o-ring used for a shaft for operating a seal ring when a process gas is used in a pendulum pressure control valve, and is attached between a flow path wall surface and the seal ring. The o-ring and the vacuum grease used on each o-ring surface and sliding surface are shielded from the process gas by blocking the atmosphere of the vacuum process chamber to protect the o-ring and protect the o-ring. Ring and vacuum grease force The purpose of this product is to prevent contamination of the vacuum process chamber by the generated fine particles, and to suppress adverse effects on the product caused by them.

 [0007] The present inventor conducted extensive research to prevent troubles in the vacuum process chamber due to the O-ring and vacuum dulling in the pendulum pressure control valve. The purpose can be achieved by placing an annular protective band between the ring and vacuum grease coated o-ring surface and sliding surface and the vacuum process chamber, which also has a corrosion resistant material force to prevent fluids from entering and exiting. Based on this finding, the present inventors have made the present invention.

[0008] That is, the present invention relates to a frame 1 having a circular flow channel 2 for communicating a vacuum process chamber and a vacuum pump at the center, and a flow channel that rotates in a direction perpendicular to the flow channel axis. The closed state in which the flow of the fluid passing through the flow path is blocked by approaching the seal ring, which will be described later, and the flow path is opened and separated from the seal ring 8 by rotating. The slide plate 7 that forms an open state that allows the flow of fluid by sliding, and the slide plate 7 is pressed or depressurized while sliding between the flow passage peripheral wall surface and the seal ring 8 outer peripheral surface. When a process gas is used in a pendulum pressure control valve composed of a seal ring 8 that creates a gap with or closes to the surface of the plate 7, the shaft slide of the shaft 14 for operating the seal ring 8 is used. From the fine particles generated from the O-rings 10 and 11 attached to the sliding surface between the moving surface and the flow path wall surface and the seal ring 8, and the vacuum grease used for each sliding surface, the atmosphere in the vacuum process chamber An annular protective band 12, 13 made of two corrosion-resistant materials is placed on the outer wall surface of the frame wall and the seal ring so as to sandwich the O-ring. It is intended to provide a vacuum valves, wherein.

 Brief Description of Drawings

FIG. 1 is a longitudinal sectional view of a vacuum valve showing an example of the present invention.

 FIG. 2 is a partial cross-sectional view showing the main part of FIG.

 [Fig. 3] is a slope view of a conventional example.

 FIG. 4 is a partial cross-sectional view in which a part of FIG. 3 is cut away.

 BEST MODE FOR CARRYING OUT THE INVENTION

 Next, the present invention will be described in detail with reference to the accompanying drawings.

 Fig. 3 is a perspective view of a conventional pendulum pressure control valve equipped with an O-ring as seen from below, and Fig. 4 is a partial cross-sectional view with a part thereof cut away.

 [0011] In these figures, the frame 1 has a fluid flow path 2 that spans an inlet 3 connected to a vacuum process chamber and an outlet 4 connected to a vacuum pump. A vacuum process chamber side connection flange 5 and a vacuum pump side connection flange 6, that is, an annular surface are provided around the edges of the inlet 3 and outlet 4 of the flow path of the frame 1. In this valve, a slide plate 7 is disposed inside the frame 1 so as to be rotatable between an open position and a closed position of the fluid flow path 2.

[0012] When the slide plate 7 moves from the open position to the closed position, the slide plate 7 reduces the flow rate of the fluid passing through the fluid flow path 2, and is supplementarily directed toward the vacuum pump side connection flange 6 of the outlet 4. And move to a position that can be finely adjusted to prevent the flow of fluid through the outlet 4 It has paid off. The inlet 3 of this pendulum type valve is connected to the vacuum process chamber, and the outlet 4 is connected to a vacuum pump to exhaust the high purity gas introduced into the supply section connected to the vacuum process chamber. At this time, by controlling the conductance by the movement of the slide plate 7, the pressure in the vacuum process chamber is controlled to a set constant pressure, and semiconductor devices are manufactured and coated.

In FIG. 3, the valve further has a seal ring 8, and the seal ring 8 coaxially surrounds the fluid flow path 2 with the flange surface 5 of the inlet 3 of the frame body 1 and the slide plate 7. It is arranged between.

 [0014] In the seal ring 8, two O-rings 9 and 11 made of an elastic material are arranged in a state of being embedded in the insertion grooves. One O-ring 9 is disposed between the seal ring 8 and the slide plate 7, and the other O-ring 11 is disposed between the seal ring 8 and the inner wall surface of the inlet 3.

 Next, FIG. 1 is a longitudinal sectional view showing an example of the vacuum valve of the present invention, and FIG. 2 is a partial sectional view showing an essential part thereof.

 In these drawings, the vacuum valve of the present invention includes a frame 1 having a circular channel 2 formed in the center at an inlet 3 connected to a vacuum process chamber at the upper part and an outlet 4 connected to a vacuum pump at the lower part. It consists of a slide plate 7 and a seal ring 8. The slide plate 7 is rotated in the vertical direction with respect to the flow path axis so as to form a closed position for blocking the flow of the flow path and an open position for allowing the flow.

 [0016] When the slide plate 7 is brought into the closed position and is in a completely closed state, the seal ring 8 is pressed by the shaft 14 for operating the slide plate 7 and is embedded in the fitting groove of the seal ring 8. The arranged O-ring 9 completely stops the flow of fluid from the inlet 3 to the outlet 4 of the fluid flow path 2.

[0017] The seal ring 8 is provided with an O-ring 11 on the sliding surface on the side surface of the flow path, and the shaft 14 for operating the seal ring 8 is provided with an O-ring 10 for sealing the sliding portion. In addition, the grease applied to these O-rings 10, 11 and the sliding surfaces of the vacuum process chamber connected to the inlet 3 is completely molded by the corrosion resistant material to completely shut off the atmosphere. Annular protective band made elastic by processing into a bellows shape 12 , 13 are arranged.

 This annular protective band may be fixed to the surface of the seal ring 8 or may be fixed to the channel wall surface. That is, the annular protective bands 12, 13 may be fitted with a fitting groove provided on the surface of the seal ring 8, or a fitting groove may be provided on the wall surface of the flow path. Also good.

 [0018] The annular protective bands 12, 13 need to be formed of a corrosion-resistant material. As such a material, for example, plastic is used, and fluorine resin such as PTFE, PFA, PFEP, ETFE, PCTFE, ECTFE, PVDF, and PVF is particularly preferable.

 In the vacuum valve of the present invention, the O-rings 10 and 11 disposed in the sliding portion and the vacuum process chamber are blocked by the annular protective bands 12 and 13, so that they are in contact with the process gas. This prevents damage to the O-ring and prevents particles generated from the O-ring from entering the vacuum process chamber and adhering to the surface of the workpiece, causing diffu- lation. In addition, the grease applied to the sliding part does not adversely affect the products in the vacuum process chamber.

 Industrial applicability

[0020] According to the present invention, the grease applied to the sliding portion of the conventional vacuum valve force seal ring has the disadvantage that it enters the vacuum process chamber and contaminates the product being processed. This can be improved by blocking the O-ring attached to the sliding part from the vacuum process chamber.

 Also, since these O-rings do not come into contact with the process gas in the vacuum process chamber, the O-ring force prevents the O-ring from being damaged by the process gas. Does not contaminate the product inside

Therefore, the vacuum valve of the present invention is suitable for pressure control in a vacuum process chamber such as chemical vapor deposition (CVD), plasma etching, sputtering, etc. used in the manufacture of semiconductor devices.

Claims

The scope of the claims  [1] A frame having a circular flow channel at the center for communicating the vacuum process chamber and the vacuum pump, and rotating in a direction perpendicular to the flow channel axis to close the flow channel, and a seal ring described later The slide forms a closed state in which the flow of fluid passing through the flow path is blocked by approaching the flow path, and an open state in which the flow of the fluid is opened by rotating and separating the seal ring force. The seal ring force that presses or depressurizes the slide plate to create a gap between the plate and the slide plate surface while sliding between the plate and the flow passage peripheral wall surface and the seal ring outer peripheral surface. In the constructed pendulum pressure control valve, when using process gas, the sliding surface of the shaft and the flow path wall surface and the seal ring for operating the seal ring are used. O-ring force attached to each sliding surface between the frame wall surface and seal ring to block the vacuum process chamber atmosphere from the generated fine particles and vacuum grease used on each sliding surface A vacuum valve characterized in that an annular protective band made up of two corrosion-resistant materials is disposed on the outer wall surface at a position sandwiching the O-ring. [2] The vacuum valve according to claim 1, wherein the annular protective band is fixed to the seal ring surface. [3] The vacuum valve according to claim 1, wherein the annular protective band is fixed and arranged on the wall surface of the flow path. [4] The vacuum valve according to claim 1, 2 or 3, wherein the annular protective band is made of plastic. [5] The vacuum nozzle according to claim 4, wherein the plastic is fluorine resin.