Wafer aligner in center of front end frame of vacuum system

Details Wafer aligner in center of front end frame of vacuum system Wafer aligner in center of front end frame of vacuum system

1998-01-14

2001-08-07

Hess, Douglas (Department: 2167)

Material or article handling

Apparatus for charging a load holding or supporting element...

Transporting means carries load to at least one of a...

C414S217000, C414S416060, C414S936000, C414S937000, C414S938000, C414S806000

Reexamination Certificate

active

06270306

ABSTRACT:

FIELD OF THE INVENTION
The present invention generally relates to apparatuses used to handle wafers commonly used in the fabrication of integrated circuits and flat panel displays. Specifically, the present invention relates to placement and use of wafer aligners used in a vacuum processing system to align, or orient, a wafer according to the requirements of a process to be performed on the wafer in the vacuum processing system.
BACKGROUND OF THE INVENTION
Vacuum processing systems for processing 100 mm, 200 mm, 300 mm or other diameter wafers are generally known. An example of a typical vacuum processing system
10
is shown in
FIG. 1
a
. The system
10
typically has a centralized transfer chamber
12
mounted on a monolith platform (not shown). The transfer chamber
12
is the center of activity for the movement of wafers being processed in the system. One or more process chambers
14
attach to the transfer chamber
12
at valves through which the wafers are passed by a robot
16
in the transfer chamber
12
. The valves are selectively opened and closed to isolate the process chambers
14
from the transfer chamber
12
while wafers are being processed in the process chamber
14
. Physically, the process chambers
14
are either supported by the transfer chamber
12
and its platform or are supported on their own platform. Inside the system
10
, the transfer chamber
12
is typically held at a constant vacuum; whereas, the process chambers
14
may be pumped to a greater vacuum for performing their respective processes. Afterward, the chamber pressure must be returned to the level in the transfer chamber
12
before opening the valve to permit access between the chambers.
The transfer chamber
12
has facets to support four process chambers
14
and two load lock chambers
18
. Other transfer chambers may have a total of only four or five facets. The process chambers
14
include rapid thermal processing (RTP) chambers, physical vapor deposition (PVD) chambers, chemical vapor deposition (CVD) chambers, etch chambers, etc. The productivity of a vacuum processing system
10
is increased when more process chambers
14
are mounted to the transfer chamber
12
, because more wafers can be processed at a given time. Additionally, less space is required in the manufacturing facility if the productivity of the system is maximized.
Access to the transfer chamber
12
for wafers from the exterior of the system
10
, or from the manufacturing facility, is typically through one or more load lock chambers
18
. The load lock chambers
18
cycle between the pressure level of the ambient environment and the pressure level in the transfer chamber
12
in order for the wafers to be passed therebetween. The load lock chambers
18
attach to an optional mini-environment
20
which transfers wafers in a very clean environment at atmospheric pressure from wafer pods seated on pod loaders
22
to the load lock chambers
18
. Typically, the transfer chamber
12
or the mini-environment
20
has a wafer orienter, or aligner
24
for aligning a wafer so that the wafer is properly oriented when it is loaded into a process chamber
14
or a load lock chamber
18
. For systems
10
that do not have a mini-environment
20
, the wafer aligner
24
is attached to the transfer chamber
12
at one of the locations for a process chamber
14
. For systems
10
that have a mini-environment
20
, the wafer aligner
24
is located in a small side chamber
26
attached to the mini-environment
20
between the pod loaders
22
as shown in
FIG. 1
a
or at one end
60
,
62
of the track system for the track-mounted robot
28
. One or more track-mounted mini-environment robots
28
,
29
transfer the wafers from the pod loaders
22
to the load lock chambers
18
.
In a typical loading procedure in a mini-environment
20
having a wafer aligner side chamber
26
, a robot
28
moves a wafer out of a pod positioned on a pod loader
22
in the direction of arrow A. The robot
28
moves to the wafer aligner
24
in the direction of arrow B. The robot
28
inserts the wafer into the wafer aligner
24
in the direction of arrow C. After the wafer aligner
24
aligns the wafer, the robot
28
retrieves the wafer in the direction of arrow D. The robot
28
moves in the direction of arrow E toward the load lock chamber
18
to position the wafer for delivery therein. Finally, the robot
28
inserts the wafer into the load lock chamber
18
in the direction of arrow F. Thus, six movements of the wafer are required to move the wafer from a pod to a load lock chamber
18
. If the number of movements can be reduced, then the time to load the load lock chamber
18
can be reduced and the throughput of the system
10
increased.
A system
10
typically has only one robot
28
, but if the system
10
has two robots
28
,
29
, as shown in
FIG. 1
a
, then the two robots
28
,
29
must share the wafer aligner
24
and the space directly in front of the wafer aligner
24
in the mini-environment. If the first robot
28
moves into this space to deliver a wafer to the wafer aligner
24
or a load lock chamber
18
, then the first robot
28
may interfere with the second robot's performance. The first robot
28
must move out of the way before the second robot
29
can move into this space. Thus, if the movements of the robots
28
,
29
are not carefully coordinated, then the second robot
29
may become idle while waiting for the first robot
28
to finish accessing the wafer aligner
24
or the load lock chamber
18
. Time spent waiting by one robot
29
for the other robot
28
to move causes an increase in the time to load the wafers and a decrease in the throughput of the system
10
.
Another example of a typical vacuum processing system
30
is shown in
FIG. 1
b
. This example has a transfer chamber
32
mounted on a monolith platform (not shown) and four process chambers
34
mounted to the transfer chamber
32
similar to the example in
FIG. 1
a
, but the system
30
also has a buffer chamber
36
for staging the movement of wafers through the system
30
and for providing pre-processing and post-processing of the wafers as needed. Disposed between the transfer chamber
32
and the buffer chamber
36
are a pre-clean chamber
38
and a cool-down chamber
40
. The buffer chamber robot
42
places wafers to be processed into the pre-clean chamber
38
, and the transfer chamber robot
44
removes the wafers from the pre-clean chamber
38
and transfers the wafers to one or more process chambers
34
for processing. The pre-clean chamber
38
provides cleaning of the wafers and transitioning from the buffer chamber pressure to the transfer chamber pressure. After processing, the transfer chamber robot
44
places the wafers in the cool-down chamber
40
, and the buffer chamber robot
42
removes the wafers from the cool-down chamber
40
. The cool-down chamber
40
provides for post-process cooling of the wafers and for pressure transitioning from the transfer chamber pressure to the buffer chamber pressure. The buffer chamber robot
42
transfers the wafers to the load lock chambers
46
for return to the ambient environment or transfers the wafers to an expansion chamber
48
for additional processing or post-processing or to a cool-down chamber
50
for further cooling before transferring the wafers to the load lock chambers
46
. The load lock chambers
46
transition the wafers between the buffer chamber pressure and the ambient environment pressure.
As in the system
10
shown in
FIG. 1
a
, the load lock chambers
46
have an optional mini-environment
54
attached thereto. The mini-environment
54
has pod loaders
56
attached thereto and one or more mini-environment robots
58
disposed therein for moving the wafers between the load lock chambers
46
and wafer pods seated on the pod loaders
56
. The mini-environment
54
, however, does not have a wafer aligner in a side chamber, because such systems
30
have typically attached a wafer aligner chamber
52
to the buffer chamber
36
for aligning the wafe

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