Valves and valve actuation – With means to increase head and seat contact pressure – Gate valve
Reexamination Certificate
2001-10-23
2002-12-03
Yuen, Henry C. (Department: 3754)
Valves and valve actuation
With means to increase head and seat contact pressure
Gate valve
C251S279000
Reexamination Certificate
active
06488262
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a gate valve used on, e.g., a load lock chamber or a process chamber in a semiconductor processing system for subjecting a target substrate, such as a semiconductor wafer, to a process. The term “semiconductor process” used herein includes various kinds of processes which are performed to manufacture a semiconductor device or a structure having wiring layers, electrodes, and the like to be connected to a semiconductor device, on a target substrate, such as a semiconductor wafer or an LCD substrate, by forming semiconductor layers, insulating layers, and conductive layers in predetermined patterns on the target substrate.
BACKGROUND ART
Conventionally, a structure utilizing a link mechanism or a cam mechanism is known as a driving mechanism for a gate valve. For example, Jpn. Pat. Appln. KOKAI Publication No. 5-196450 discloses a gate valve employing a link mechanism, as shown in FIG.
10
. Jpn. Pat. Appln. KOKAI Publication No. 10-159999 discloses a gate valve employing a cam mechanism, as shown in
FIGS. 11A and 11B
.
The gate valve
100
shown in
FIG. 10
is disposed between a load lock chamber
110
and a process chamber
120
. The gate valve
100
includes a base body
102
and a valve plug
105
disposed in a gate casing
106
. The base body
102
is connected to an actuator
101
. A guide rail
107
is disposed on the wall of the gate casing
106
on the load lock chamber
110
side, so that the base body
102
is guided to move up and down. The valve plug
105
is connected to the base body
102
by links
103
and
104
at upper and lower positions. The valve plug
105
is further connected to the base body
102
by a spring
108
. The valve plug
105
opens and closes an opening portion
121
of a process chamber
120
.
When the opening portion
121
of the process chamber
120
is closed, the actuator
101
is activated to integratedly move up the base body
102
and the valve plug
105
along the guide rail
107
. Even after a roller
109
disposed at the top of the valve plug
105
comes into contact with the ceiling of the gate casing
106
, the base body
102
keeps moving up. Consequently, the valve plug
105
cannot move up any more, but moves toward the opening portion
121
of the process chamber
120
against the action of the spring
108
while rotating the roller
109
. When the base body
102
reaches the upper end, the height of the base body
102
is leveled with that of the valve plug
105
. At this time, the valve plug
105
is strongly pushed against the opening portion
121
of the process chamber
120
by the links
103
and
104
, so that the opening portion
121
is closed.
When the opening portion
121
is opened, the actuator
101
is activated in the opposite direction to move down the base body
102
. Consequently, the valve plug
105
is pulled by the spring
108
toward the base body
102
, so that the opening portion
121
is opened. Then, the base body
102
moves down further, and the valve plug
105
returns to the initial state by the action of the spring
108
.
The gate valve
100
shown in
FIG. 10
, i.e., disclosed in Jpn. Pat. Appln. KOKAI Publication No. 5-196450, employs members, such as the guide rail
107
and the spring
108
, other than the link mechanism, at positions near the valve plug
105
, to realize a sliding movement of the base body
102
and the valve plug
105
, and their movement to/from the opening portion. As a result, this structure entails a problem in that the roller
109
comes into contact with the inner wall of the gate casing
106
, thereby most likely generating particles.
On the other hand, the gate valve
200
shown in
FIGS. 11A and 11B
includes a valve plug
201
for opening and closing an opening portion
210
. A pair of right and left side plates
202
are fixed to the valve plug
201
at each of the upper and lower levels. Each of the side plates
202
is provide with a first guide groove
203
formed therein and having a unique shape.
The gate valve
200
also includes valve plug driving rods
205
, which are provided with second guide grooves
204
formed therein and each having a unique shape corresponding to the first guide groove
203
. The valve plug driving rods
205
are connected to the valve plug
201
by shaft rollers
206
each inserted in the first and second guide grooves
203
and
204
. The valve driving rods
205
are further connected to the side plates
202
by springs
207
.
FIG. 11B
is an enlarged view showing the relationship between the first and second guide grooves
203
and
204
, and the roller
206
. As shown in
FIG. 11B
, when the opening portion
210
is in an open state, the guide grooves
203
and
204
are displaced from each other, viewed from a lateral side.
When the opening portion
210
is closed, the valve plug driving rods
205
are activated to move down the valve plug
201
with a gap interposed between the valve plug
201
and the valve seat
211
. The valve plug
201
comes into contact with a stopper
212
below the opening portion
210
, but the valve plug driving rods
205
move down further against the action of the springs
207
. Consequently, the rollers
206
slightly shift the side plates
202
through the first guide grooves
203
toward the opening portion
210
, and finally push the valve plug
201
against the valve seat
211
.
When the opening portion
210
is opened, the valve plug driving rods
205
move up. At this time, the rollers
206
move up in the respective first guide grooves
203
by the springs
207
to separate the valve plug
201
from the valve seat
212
. Then, the valve plug driving rods
205
further move up, so that the valve plug
201
moves up with the gap kept between the valve plug
201
and the opening portion
210
to return the initial state, while the rollers
206
maintain the state shown in FIG.
11
B.
The gate valve
200
shown
FIGS. 11A and 11B
, i.e., disclosed in Jpn. Pat. Appln. KOKAI Publication No. 10-159999, employs the first and second guide grooves
203
and
204
to realize the up/down movement of the valve plug
201
, and its movement to/from the opening portion. As a result, this structure requires the guide grooves to be worked with high accuracy, and also entails a problem in that particles are easily generated near the valve plug
201
and the opening portion
210
.
DISCLOSURE OF INVENTION
An object of the present invention is to provide a gate valve for a semiconductor processing system, which hardly generates particles near a valve seat (opening portion) and a valve plug.
According to a first aspect of the present invention, there is provided a gate valve for a semiconductor processing system, comprising:
a base frame configured movable in a first direction to move toward and away from a valve seat, which surrounds an opening portion and has a first seal surface facing a first reference plane;
a first stopper configured to define a movement limit of the base frame on the valve seat side;
a swing frame attached to the base frame, and configured rotatable on a second reference plane perpendicular to the first reference plane;
a valve plug attached to the swing frame, and having a second seal surface to engage with the first seal surface thereby to close the opening portion;
a link mechanism connecting the swing frame to the base frame, and configured to bend and stretch while flexing an intermediate portion;
a driving mechanism connected to the intermediate portion, and configured to move the intermediate portion in the first direction; and
a biasing member configured to apply a resistant force against rotation of the swing frame relative to the base frame,
wherein, it is preset that, when the opening portion is closed, the intermediate portion is moved by the driving mechanism toward the valve seat to first cause the base frame to move until the base frame comes into contact with the first stopper, and then cause the link mechanism to bend or stretch thereby to rotate the swing frame, such that the valve plug seats itself on the valve seat, a
Bastianelli John
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tokyo Electron Limited
Yuen Henry C.
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