Process system with transfer unit for object to be processed

Details Process system with transfer unit for object to be processed Process system with transfer unit for object to be processed

2000-04-13

2002-05-28

Bueker, Richard (Department: 1763)

Coating apparatus

Gas or vapor deposition

Multizone chamber

C414S217000, C414S936000, C414S939000

Reexamination Certificate

active

06395094

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a process system, equipped with a transfer unit for an object to be processed, such as a semiconductor wafer, for carrying out a predetermined process for the object.
2. Description of the Related Art
In general, in order to produce a semiconductor integrated circuit, various processes, such as deposition, etching, oxidation and diffusion, are carried out for a wafer. In addition, in order to improve throughput and yields by the scale down and high integration of the semiconductor integrated circuit, a so-called clustered-process-system has been proposed. In such a process system, a plurality of process chambers for carrying out the same process or different processes are connected to each other via a transfer chamber so that processes in various processes can be sequentially carried out without the exposure of the wafer to the atmosphere.
FIG. 8
is a schematic diagram showing an example of such a conventional clustered-process-system. As shown in this figure, a process system
2
comprises three process chambers
4
A,
4
B and
4
C, and two cassette housing chambers
12
A and
12
B. The process system
2
also comprises a first transfer chamber
10
, a second transfer chamber
6
and two load-lock chambers
8
A and
8
B having a preheating or cooling mechanism.
The three process chambers
4
A through
4
C are connected to the second transfer chamber
6
. The two load-lock chambers
8
A and
8
B are provided in parallel between the first and second transfer chambers
10
and
6
. The two cassette housing chambers
12
A and
12
B are connected to the first transfer chamber
10
. Between the respective chambers, gate valves G capable of being airtightly open and closed are provided.
First and second articulated transfer arms
16
and
14
capable of bending, stretching and rotating are provided in the first and second transfer chambers
10
and
6
, respectively. By holding and transporting a semiconductor wafer W by these transfer arms
16
and
14
, the semiconductor wafer W is transferred. In the first transfer chamber
10
, an aligning unit
22
comprising a turntable
18
and an optical sensor
20
is provided. The aligning unit
22
is designed to rotate the wafer W, which is introduced from the cassette housing chamber
12
A or
12
B, to detect the orientation flat or notch of the wafer W to align the wafer W.
With respect to the process of the semiconductor wafer W, an unprocessed semiconductor wafer W is first taken out from a cassette in any one of the cassette housing chambers, e.g., a cassette C in the cassette housing chamber
12
A, by means of the first transfer arm
16
in the first transfer chamber
10
, which is held at atmospheric pressure in an atmosphere of N
2
, to be mounted on the turntable
18
of the aligning mechanism
22
in the first transfer chamber
10
. While the turntable
18
rotates to align the wafer W, the transfer arm
16
stands by without moving. The time required to carry out the alignment is, e.g., about 10 to 12 seconds.
After the alignment of the wafer W is completed, the standby transfer arm
16
holds the aligned wafer W again, and introduces the wafer W into any one of the load-lock chambers, e.g., the load-lock chamber
8
A. In the load-lock chamber
8
A, the wafer W is preheated if necessary, while the interior of the load-lock chamber
8
A is evacuated to a predetermined pressure. The time required to carry out the preheating or evacuation is, e.g., about 30 to 40 seconds.
If such a preheating operation is completed, the load-lock chamber
8
A is communicated with the second transfer chamber
6
, which is previously held in a vacuum state, by opening the gate valve G. Then, the preheated wafer W is held by the second transfer arm
14
to be transferred into a predetermined process chamber, e.g., the process chamber
4
A, in which a predetermined process, e.g., a process for depositing a metal film or insulating film, is carried out. The time required to carry out this process is, e.g., about 60 to 90 seconds.
The processed semiconductor wafer W is introduced into, e.g., the original cassette C in the cassette holding chamber
12
A, along the reverse route of the above described route. In the route for returning the processed wafer W, the wafer W is transferred after being cooled to a predetermined temperature using, e.g., the other load-lock chamber
8
B. The time to cool and return the wafer W to atmospheric pressure is about 30 to 40 seconds. Alternatively, before the processed wafer W is introduced into the cassette C, the wafer W may be aligned by the aligning mechanism
22
if necessary.
Furthermore, when the semiconductor wafer W is oxidized or diffused, there are some cases where it is not required to hold the transfer unit at a reduced pressure atmosphere. In that case, there are some cases where a buffer part capable of causing a plurality of wafers W to stand by for timing is provided in place of the load-lock chambers
8
A and
8
B capable of being evacuated.
By the way, in a process system of this type, in the above described case, the time required to treat a single wafer W is, e.g., about 60 to 90 seconds, which is some longer than the time required to carry out the alignment or preheating, although it depends on the contents of process. Therefore, the plurality of process chambers
4
A through
4
C are provided to effectively carry out operations. As a result, there is a problem in that the throughput of products is rate-controlled by the transfer time for the wafer W in the transfer unit. For example, during the introduction of the wafer W, until the alignment of the wafer W is completed after the wafer W is mounted on the turntable
18
of the aligning mechanism
22
, the first transfer arm
16
stands by without moving and can not other transfer operations. In addition, after the alignment of the wafer W is completed, the first transfer arm
16
is monopolized to transfer the wafer W to the load-lock chamber
8
A.
For such a reason, since the transfer arm is not efficiently used, there is a problem in that it is not possible to sufficiently improve throughput. In addition, since the number of delivery operations of the wafer is relatively large in the above described wafer transfer unit, aligning errors are accumulated every delivery operation, so that there is also a problem in that the final precision of the alignment deteriorates.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to eliminate the aforementioned problems and to provide a so-called cluster-tool-type process system capable of efficiently transferring an object to be processed, to improve the throughput in the process for the object and to improve the precision of the alignment for the object.
In order to accomplish the aforementioned and other objects, according to one aspect of the present invention, a process system comprises: a housing chamber for housing therein an object to be processed; a process chamber for carrying out a predetermined process for the object; a transfer chamber for establishing a communication between the housing chamber and the process chamber; a first transfer unit for delivering the object between the transfer chamber and the housing chamber; a second transfer unit for delivering the object between the transfer chamber and the process chamber; and an aligning unit for aligning the object, wherein the aligning unit is arranged in an overlapping range of transfer ranges of the first and second transfer units.
Thus, since the aligning unit is arranged in a transfer range common to the first and second transfer units, the second transfer unit can take the aligned object after the object is mounted on the aligning unit by the first transfer unit. Therefore, immediately after the first transfer unit mounts the object on the aligning unit, the first transfer unit can move to carry out the transfer operation of another object without standing by until the aligning operation is completed. As a result, it i

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