Valves and valve actuation – With means to increase head and seat contact pressure – Gate valve
Reexamination Certificate
2001-04-23
2003-05-20
Scherbel, David A. (Department: 3754)
Valves and valve actuation
With means to increase head and seat contact pressure
Gate valve
C251S158000, C137S341000
Reexamination Certificate
active
06565066
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gate valve which can open and close, and seal an aperture of a vacuum processing chamber. For example, the present invention relates to a gate valve which can open and close, and seal an aperture of a vacuum processing chamber to be used in a process of manufacturing a semiconductor device, etc.
2. Description of the Related Art
In dry-etching, sputtering and epitaxial wafer forming processes, etc. in manufacturing process of a semiconductor device, for example, there is used a vacuum processing device having a construction of a multi-chamber to which a plurality of vacuum processing chambers are connected as shown in FIG.
16
.
In a vacuum processing device
301
in
FIG. 16
, a plurality of vacuum processing chambers
305
which conduct various kinds of processing are connected to an outer circumference of a conveying chamber
302
to which a wafer W is conveyed in and out. The movement between the conveying chamber
302
of the wafer W and each of vacuum processing chambers
305
is conducted through a gate G. The opening, closing and sealing of the gate G are conducted by a gate valve which is not shown in the drawings.
In the vacuum processing device
301
in
FIG. 16
, the wafer W is conveyed in the conveying chamber
302
by a conveying device which is not shown in the drawings through a conveying entrance
303
of a conveying channel
304
, and is supported by a vacuum conveying robot
307
provided in the conveying chamber
302
. When the wafer W is supported by the vacuum conveying robot
307
, the conveying entrance
303
is closed, and a vacuum suction is conducted in the conveying chamber
302
. At this time, each of said gate valves is in the state of sealing the respective gates. When the vacuum suction in the conveying chamber
302
is completed, each of the gate valves is actuated to open the gate G, and the wafer W is conveyed into a predetermined vacuum processing chamber by the vacuum conveying robot
307
. For the processing in the vacuum processing chamber, each of the gate valves is actuated to close the gate G, and a predetermined processing is conducted on the wafer W. When the predetermined processing on the wafer W is completed, each of the gate valves is actuated to open the gate G, and the wafer W is carried out from the vacuum processing chamber by the vacuum conveying robot
307
, and is automatically conveyed outside the vacuum processing device
301
through the conveying entrance
303
.
As a gate valve
306
which can open and close, and seal the gate G in the above-mentioned vacuum processing device
301
, the structures as shown in FIG.
17
and
FIG. 18
are used.
In
FIG. 17
, a conveying chamber
202
is communicated with a vacuum processing chamber
203
through a gate G. The opening and closing of the gate G are conducted by a gate valve
201
, and the gate valve
201
includes a valve plate
205
to conduct the opening and closing and sealing of the gate G, a valve rod
206
which has one end to which the valve plate
205
is fixed, and is supported to be capable of being moved straight and to be able to be inclined around a predetermined shaft
208
, a seal bellows
207
which seals a space between the conveying chamber
202
and the valve rod
206
, and an actuating means which is not shown in the drawings and moves straight or tilts the valve rod
206
.
In
FIG. 17
, the gate valve
201
is in the state of opening the gate G. In order to close and seal the gate G, as shown in
FIG. 18
, the valve rod
206
is moved straight to be moved to the position where the valve plate
205
closes the gate G, and the valve rod
206
is tilted around a shaft
208
. As a result, the valve plate
205
presses an O-ring
204
provided in the outer circumference of the gate G, so that the gate G is sealed.
However, in the gate valve
201
having the above-mentioned structure, for example, it is known that an air cylinder as a straight moving means and the valve rod
206
is connected through a cam mechanism, so that the tilting of the valve rod
206
is conducted.
For instance, a gate valve using such cam mechanism is disclosed in the official gazette of Japanese Patent No. 2613171.
The cam mechanism of the gate valve disclosed in the official gazette of Japanese Patent No. 2613171 is comprised of a pin which connects a yoke actuated straight by an air cylinder and a block fixed to a lower end portion of a valve rod, and a slanted elongate hole engaged with the pin.
In the cam mechanism having the construction, the pin slides with respect to the slanted elongate hole, and thus, a tilting force which tilts the valve rod is generated.
For instance, a gate valve using the cam mechanism is also disclosed in U.S. Pat. No. 5,120,019.
The cam mechanism disclosed in U.S. Pat. No. 5,120,019 is comprised of a cam plate including a cam surface which is moved straight by an air cylinder, and a cam follower comprised of a roller rotatably provided to a valve rod, and has the construction in which the roller is engaged with a cam surface of the straight moving cam plate so that the valve rod is tilted.
However, in the construction of the cam mechanism disclosed in the official gazette of Japanese Patent No. 2613171, because the pin slides over the inner circumferential surface of the slanted elongate hole, there is a disadvantage that a sliding friction is occurred therebetween and noise is easily generated, and thus, silence is insufficient.
Moreover, because the sliding friction is occurred between the pin and the inner circumferential surface of the slanted elongate hole, there is a disadvantage that the output of the air cylinder as an actuating means which actuates a cam mechanism needs to be raised, or it is difficult that the cam mechanism is smoothly operated, or the pin and the inner circumferential surface of the slanted elongate hole are easily worn, so that stable operation for long time period cannot be assured.
Further, in the cam mechanism of the construction disclosed in U.S. Pat. No. 5,120,019, because the roller as a cam follower rolls over the cam surface of the cam plate, it is difficult that the sliding friction is occurred, and generally, rolling friction is occurred. Accordingly, though the operation of the cam mechanism is comparatively smooth and the silence is excellent, because the roller needs to be rotatably supported by the supporting shaft, the structure becomes complicated, a bearing is needed between the roller and the supporting shaft, and there was a problem in the reliability of the bearing because a large radial load is applied to the bearing.
In addition, since there is a limitation to reduce a diameter of the roller, the structure was disadvantageous in view of compactness.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a gate valve including a cam mechanism in which the structure thereof is simplified and small-sized so that low-price is possible.
A further object of the present invention is to provide a gate valve which has smooth operation so that high speed movement is possible, and has sufficient silence and high reliability.
Further, another object of the present invention is to provide a gate valve which can conduct securely the releasing operation from the sealing state of an aperture by a valve plate.
A gate valve of the present invention comprises: a valve plate which is provided in an air-tight chamber, and open and close an aperture of the air-tight chamber and seal the aperture by tilting with respect to said aperture; a valve rod which has one end to which said valve plate is fixed, and is supported to be movable in a predetermined straight movement direction for opening and closing the aperture and to be able to tilt around a predetermined tilting axis; a sealing means which seals a space between said valve rod and said air-tight chamber to be movable; a restriction means which restricts the straight movement in the direction to close said aperture of said valve plate at a closed position where
Mori Koichi
Osawa Yoshio
Tamura Yuzuru
Cartagena Melvin A.
Eagle Industry Co. Ltd.
Jacobson & Holman PLLC
Scherbel David A.
LandOfFree
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