Material or article handling – Apparatus for moving material between zones having different... – For carrying standarized mechanical interface type
Reexamination Certificate
2002-01-07
2004-07-20
Brahan, Thomas J. (Department: 3652)
Material or article handling
Apparatus for moving material between zones having different...
For carrying standarized mechanical interface type
C251S193000, C251S324000, C414S217000, C414S939000
Reexamination Certificate
active
06764265
ABSTRACT:
BACKGROUND OF THE INVENTION
Various types of semiconductor manufacturing equipment are used to process semiconductor wafers during the manufacturing of integrated circuits (IC's). For example, chemical vapor deposition (CVD) systems are used to deposit dielectric and conductive layers over a wafer, plasma etch systems are used to etch a wafer or a layer formed over the wafer, and physical vapor deposition or “sputter” systems are used to physically deposits conductive layers over a wafer. These various processes are usually performed within sealed processing chambers so that the processing conditions can be tightly controlled.
A common way of transferring a wafer into a processing chamber and then subsequently removing it is through a “slit valve” in a wall of the processing chamber. A slit valve generally includes an elongated, usually horizontal, aperture formed in the wall. The aperture is sufficiently wide and high to permit the passage of a semiconductor wafer supported by the blade of a robotic wafer handling arm, and is surrounded by a valve seat. An elongated valve closure selectably engages the seat to close the aperture or disengages from the seat to open the aperture.
When the slit valve is closed, a gas-tight seal is required in order to isolate the chamber from external influences. This usually requires an elastomeric gasket or seal, such as an O-ring seal; disposed between the valve seat and the closure. Since the pressure on one side of the slit valve can be as high as atmospheric pressure, while the pressure on the other side of the slit valve can be as low as 10
−8
torr, one atmosphere of pressure is often applied to the closure to ensure that the slit valve does not leak even under the most adverse of conditions. This amount of pressure tightly compresses the O-ring seal between the closure door and the valve seat.
FIG. 1
is a plan view of a prior art multiple chamber semiconductor processing system
100
. System
100
includes a central wafer handling chamber
102
, a wafer cassette loading/unloading (load lock) chamber
104
, and a number of wafer processing chambers
106
a
-
106
d
. System
100
is typically designed to process a single wafer
108
at a time within any one of the processing chambers
106
.
Central wafer handling chamber
102
is provided with a computer controlled robotic wafer handler
110
which can support and move the wafer
108
. A typical wafer handler
110
includes a “frog's leg” assembly
112
which is coupled at one end to a motor assembly
114
and, at the other end, to a wafer support blade
116
. The motor assembly
114
allows the blade
116
to be rotated around an axis A of the motor assembly
114
and also to be moved radially in and out relative to the axis A as indicated by an arrow
118
, by opening and closing the “frog's leg” assembly
112
in the direction of an arrow
120
. These two degrees of movement allow the wafer handler
110
to move the wafer
108
into and out of the loading/unloading chamber
104
and the processing chambers
106
a
-
106
d.
Wafer handlers, such as the handler
110
, are commercially available from such companies as Applied Materials of Santa Clara, Calif.
Central wafer handling chamber
102
is pentagonal in shape to accommodate the four processing chambers
106
a
-
106
d
and the loading/unloading chamber
104
. A slit valve assembly is disposed in a wall of each of the chambers
104
,
106
a
-
106
d
. Thus, a slit valve assembly
130
a
is disposed in a chamber wall
132
a
that forms a boundary between the handling chamber
102
and the processing chamber
106
a
. Also, a plurality of slit valve assemblies
130
b
,
130
c
,
130
d
are disposed in chamber walls
132
b
,
132
c
,
132
d
, respectively, that form a boundary between the handling chamber
102
and the other processing chambers
106
b
,
106
c
,
106
d
, respectively. Similarly, a slit valve assembly
130
e
is disposed in a chamber wall
132
e
that forms a boundary between the handling chamber
102
and the loading/unloading chamber
104
. The slit valve assemblies
130
a
-
130
e
permit the wafer
108
to pass through the walls
132
a
-
132
e
, respectively, of the handling chamber
102
into the chambers
106
a
,
106
b
,
106
c
,
106
d
and
104
, respectively. Typically, the wafer handling chamber
102
is evacuated during the wafer handling process by a vacuum pump (not shown).
In operation, a stack of wafers (not shown) is placed within the loading/unloading chamber
104
, and the slit valve assembly
130
e
is opened to permit the handler
110
to remove one or more of the wafers from the loading/unloading chamber
104
, The slit valve
130
e
is then closed and the handling chamber
102
is evacuated.
A slit valve assembly to one of the processing chambers
106
a
-
106
d
is opened to permit the wafer
108
to be placed on a wafer support or pedestal
134
a
-
134
d
, respectively, disposed in the processing chamber. As an example of a multiple processing operation, the wafer
108
is initially provided with an oxide layer and is then etched. Thus, in the initial step, the wafer
108
is to be placed in, for example, chamber
106
a
which is an oxide CVD chamber. Slit valve
130
a
is opened and the handler
110
passes the wafer
108
through the opening and places it on the pedestal
134
a
. Slit valve
130
a
is then closed and the CVD process is performed. After the completion of the CVD process, the slit valve
130
a
is opened and the wafer
108
is removed by the handler
110
and the slit valve
130
a
is closed. In the next processing step, the wafer
108
is etched in a reactive ion etch (RIE) chamber. If chamber
106
b
is an RIE chamber, slit valve
130
b
is opened, the handler
110
places the wafer
108
on the pedestal
134
b
, and the slit valve
130
b
is closed. After the RIE process is performed, the slit valve
130
b
is reopened, the handler
110
removes the wafer
108
, and the slit valve
130
b
is closed. After the wafer
108
has been completely processed and it is returned to the loading/unloading chamber
104
.
FIG. 2
is a partial sectional view of the semiconductor processing system
100
taken along line
2
—
2
of FIG.
1
. The handling chamber
102
includes a top wall
202
and a bottom wall
204
in addition to the aforementioned pentagonally arranged side walls
132
a
through
132
e
. The motor assembly
114
of the handler
110
is supported by the bottom wall
204
. Gasses, such as air, nitrogen, etc. can be released into the handling chamber
102
from a gas source
206
, via a gas inlet port
208
in the top wall
202
, and gasses can be evacuated from chamber
102
by means of a vacuum pump
210
, via a similarly situated gas outlet port
212
. It should be noted that for simplicity the second slit valve assembly
130
b
is not shown in the background of the figure.
The processing chamber
106
a
has side walls
214
,
216
, and
218
, a top wall
220
and a bottom wall
222
, and can be completely isolated from the ambient environment. Corrosive process gases such as fluorine can be released into the processing chamber
106
a
from a gas source
224
, via a gas inlet port
226
in its top wall
220
, and the chamber
106
a
can be evacuated by a vacuum pump
228
, via a similarly situated gas outlet port
230
.
The conventional slit valve assembly
130
a
includes a valve seat
232
and a closure or valve door
234
. A horizontally elongated wafer aperture
237
is provided through walls
218
,
132
a
and the valve seat
232
, and is adapted to allow passage therethrough of a wafer
108
held in a horizontal orientation.
FIG. 3A
illustrates the conventional slit valve assembly
130
a
in greater detail. As mentioned previously, the slit valve assembly includes the valve seat
232
and the closure
234
. The seat
232
extends through the wall
132
a
and forms the aperture
237
. The seat
232
further includes a sealing face
302
, an inner top wall
304
, and an inner bottom wall
306
. The sealing face
302
of the valve seat
232
lies in a
Kunze Charles S.
Le Andrew V.
Rasheed Muhammad
Applied Materials Inc.
Brahan Thomas J.
Townsend & Townsend & Crew
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