Refrigeration – Article moving means
Reexamination Certificate
2001-01-03
2002-10-08
Esquivel, Denise L. (Department: 3744)
Refrigeration
Article moving means
C062S380000
Reexamination Certificate
active
06460369
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of semiconductor processing. More particularly, the present invention relates to an apparatus and method for transporting substrates through a semiconductor processing system, wherein the apparatus and method include a temperature control mechanism. Further, the present invention relates to an apparatus and method for transporting substrates through a semiconductor processing system to generate a poly silicon film.
2. Background of the Related Art
In the semiconductor industry, there are generally two primary methods of transporting substrates through a processing system. One traditional method uses a “cluster tool” configuration, as shown in
FIG. 1. A
cluster tool platform generally refers to a modular, multi-chamber, integrated processing system. This type of processing system typically includes central wafer handling vacuum chambers
20
,
32
, and a number of peripheral processing chambers
24
,
26
,
28
, and
36
, which are generally arranged in a cluster around the central chambers. Multiple substrates or wafers
22
for processing are generally stored in cassettes
10
, and are loaded/unloaded from load locks
12
,
14
and processed under vacuum in various processing chambers without being exposed to ambient conditions. The transfer of wafers
22
for the processes is generally managed by a centralized robot
16
in a wafer handling vacuum chamber
20
or robot
30
in a second wafer handling vacuum chamber
32
, both of which are generally maintained under vacuum conditions. A microprocessor controller
38
and associated software is provided to control processing and movement of wafers. In operation, a cluster tool configuration will generally receive a substrate from a cassette
10
and process the substrate through a predetermined sequence of central wafer handling chambers
20
,
32
and peripheral processing chambers
24
,
26
,
28
, and
36
in order to generate the desired material and pattern on a wafer, which is then returned to a cassette
10
.
Although cluster tool configurations are generally preferred for processing relatively small substrates, a second method of processing substrates known as an “inline” system is generally preferred for processing larger substrates. These larger substrates, which may be formed on glass, ceramic plates, plastic sheets, or disks, for example, are often used in the manufacture of flat panel type displays in the form of active matrix televisions, computer displays, liquid crystal display (LCD) panels, and other displays. A typical glass substrate supporting a common flat panel type display may have dimensions of approximately 680 mm by 880 mm. For other display applications, the size of the substrate may be substantially larger, as required to support the particular size of the display.
FIG. 2
is a schematic side view of a typical modular inline system
40
. This type of processing system generally includes a serial or inline arrangement of processing chambers
42
,
44
disposed between a load chamber
46
and an unload chamber
48
. An elevator
50
is positioned at an entry to load chamber
46
and another elevator
52
is positioned at an exit from unload chamber
48
. Processing chambers
42
,
44
may include deposition chambers, such as chemical vapor deposition (CVD) chambers, physical vapor deposition (PVD) chambers, etch chambers, and/or other deposition and processing chambers. A carrier return line
58
is positioned above processing chambers
42
,
44
and coupled to the elevators
50
,
52
. Processing chambers
42
,
44
are typically held under vacuum or low pressure and are separated by one or more isolation valves
60
,
62
,
64
,
66
, and
68
, as shown in FIG.
3
. Typically, multiple substrates
54
,
56
,
70
,
72
are supported by a carrier
74
, as shown in
FIGS. 4 and 5
. Isolation valves
60
,
62
,
64
,
66
, and
68
are generally configured to seal the respective chambers from each other in a closed position and allow substrates
54
,
56
to be transferred through the valves to an adjacent station in an open position.
Carrier
74
, shown in
FIG. 2
, is placed adjacent elevator
50
, where substrates
54
,
56
,
70
,
72
are manually loaded onto carrier
74
at receiving station
51
. A door to the elevator
50
(not shown) opens and allows carrier
74
to be placed within the elevator on a track (not shown). The temperature and pressure inside elevator
50
is typically at ambient conditions. Isolation valve
60
opens and allows carrier
74
to be moved on the track into load chamber
46
. Load chamber
46
is sealed and pumped down to a vacuum typically in a range of about 10 mTorr to about 50 mTorr for CVD processing and about 1 mTorr to about 5 mTorr for PVD processing. Another isolation valve
62
is opened and carrier
74
is moved into a processing chamber
42
, where the substrates may be heated to a temperature suitable for processing. Another isolation valve
64
is opened and carrier
74
is moved along the track into processing chamber
44
. If processing chamber
44
is a sputtering process chamber, the chamber could include a plurality of targets
76
,
78
that sputter material from the surface of the targets facing the substrates onto substrates
54
,
56
,
70
,
72
as the substrates move along the track adjacent each target. Each sputtering target is bombarded on the side facing the substrate with ionized gas atoms (ions) created between an anode (typically the target) and a cathode (typically the grounded chamber wall) and atoms of the target are dislodged and directed toward the substrates for deposition on the substrates. Each target preferably has a magnet (not shown) disposed on the back side of the target away from the substrates to enhance the sputtering rate by generating magnetic field lines generally parallel to the face of the target, around which electrons are trapped in spinning orbits to increase the likelihood of a collision with, and ionization of, a gas atom for sputtering. Substrates
54
,
56
,
70
,
72
are then moved to an unloading chamber
48
through isolation valve
66
. Isolation valve
66
closes, thereby sealing processing chamber
44
from unload chamber
48
. Isolation valve
68
opens and allows carrier
74
to be removed from unloading chamber
48
and substrates
54
,
56
,
70
, and
72
are typically unloaded manually from carrier
74
. The substrates can also be detained in the unloading chamber to allow time for the substrates to cool. After the substrates have been unloaded, carrier
74
enters elevator
52
, whereupon elevator
52
lifts carrier
74
to carrier return line
58
. A track system (not shown) in carrier return line
58
returns the carrier to elevator
50
, which lowers the carrier into position at receiving station
51
on the other end of the processing system to receive a next batch of substrates to be processed.
While the inline system
40
is currently used for substrate transportation and production, this type of inline system has several disadvantages. In particular, carrier
74
is subject to thermal cycling as a result of the movement of carrier from the processing environment (under vacuum) to an ambient environment in elevators
50
,
52
, and then back into the processing environment. As a result of thermal cycling, deposition material is likely to peel off or be otherwise dislodged from carrier
74
and cause unwanted particle contamination on the substrates. Additionally, the use of the exposed track system, both within the processing chambers and in the ambient areas of the system, is subject to generating contaminants. Further, the use of the elevators and a track system adds a level of complexity to the system, which results in additional maintenance of the various moving components in order to avoid breakdowns. Further still, as a result of carrier
74
cycling through vacuum environments and ambient atmospheric pressure, carrier
74
is prone to absorb gases from the surrounding conditions in th
Applied Materials Inc.
Drake Malik N.
Esquivel Denise L.
Moser Patterson & Sheridan
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