Ventilation – Clean room
Reexamination Certificate
1999-09-30
2002-04-02
Lu, Jiping (Department: 3749)
Ventilation
Clean room
C454S052000, C454S057000, C055S385200
Reexamination Certificate
active
06364762
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to transferring wafers among modules of semiconductor processing equipment, and more particularly to a module having a controllable mini-environment.
2. Description of the Related Art
In the manufacture of semiconductor devices, process chambers are interfaced to permit transfer of wafers or substrates, for example, between the interfaced chambers. Such transfer is via transport modules that move the wafers, for example, through slots or ports that are provided in the adjacent walls of the interfaced chambers. For example, transport modules are generally used in conjunction with a variety of substrate processing modules, which may include semiconductor etching systems, material deposition systems, and flat panel display etching systems. Due to the growing demands for cleanliness and high processing precision, there has been a growing need to reduce the amount of human interaction during and between processing steps. This need has been partially met with the implementation of vacuum transport modules which operate as an intermediate handling apparatus (typically maintained at a reduced pressure, e.g., vacuum conditions). By way of example, a vacuum transport module may be physically located between one or more clean room storage facilities where substrates are stored, and multiple substrate processing modules where the substrates are actually processed, e.g., etched or have deposition performed thereon. In this manner, when a substrate is required for processing, a robot arm located within the transport module may be employed to retrieve a selected substrate from a load lock chamber and place it into one of the multiple processing modules.
As is well known to those skilled in the art, the arrangement of transport modules to “transport” substrates among multiple storage facilities and processing modules is frequently referred to as a “cluster tool architecture” system.
FIG. 1A
depicts a typical semiconductor process cluster architecture
100
illustrating the various chambers that interface with a vacuum transport module
106
. Vacuum transport module
106
is shown coupled to three processing modules
108
a
-
108
c
which may be individually optimized to perform various fabrication processes. By way of example, processing modules
108
a
-
108
c
may be implemented to perform transformer coupled plasma (TCP) substrate etching, layer depositions, and/or sputtering.
Connected to vacuum transport module
106
is a load lock
104
that may be implemented to introduce substrates into vacuum transport module
106
. The load lock
104
can be coupled to an atmospheric transport module (ATM)
103
that interfaces with the clean room
102
. The ATM
103
typically has region for holding cassettes of wafers and a robot that retrieves the wafers form the cassettes and moves them into and out of the load lock
104
. As is well known, the load lock
104
serves as a pressure-varying interface between vacuum transport module
106
and the ATM
103
. Therefore, vacuum transport module
106
may be kept at a constant pressure (e.g., vacuum), while the ATM
103
and clean room
102
are kept at atmospheric pressure.
FIG. 1B
illustrates a partial system diagram
150
including an atmospheric transport module (ATM)
103
which includes a filter/blower
152
a,
a robot
156
having an arm set
158
, and a shelf
154
. The shelf
154
is configured to hold a cassette
160
of wafers
162
within a cassette environment
152
b.
The cassette environment
152
b
of the ATM
103
has a door
155
which can be opened to insert or remove the cassette
160
during processing. The filter/blower
152
a
is configured to generate an air flow
170
in the ATM
103
and thus, cause the air flow substantially undisturbed through a particle screen
171
to a lower portion of the ATM
103
and then out an exhaust vent
152
c.
In addition, the ATM
103
is simplistically shown connected to the load lock
104
and to the transport module
106
. As mentioned above, the transport module
106
can then transfer wafers between selected processing modules
108
.
Although this type of prior art ATM
103
is capable of transferring wafers from the cassette
160
into and out of the load lock
104
quite efficiently, the air flow
170
has been observed to bypass the cassette environment
152
b
during the operation of the blower
152
a.
As a result, the cassette environment
152
b
remains substantially static. That is, the environment between the wafers
162
remains substantially unaffected by the air flow
170
during operation.
FIG. 1C
illustrates a more detailed view of the cassette
160
having a plurality of wafers
162
. In general, after a wafer has been processed in one of the processing modules
108
and stacked back into the cassette
160
, post-process gasses will typically hover between the respective wafers
162
. The gasses are pictorially illustrated by
166
emanating from the top surfaces of recently processed wafers
162
. A problem with having such gasses
166
between the wafers
162
is that the chemical gasses can, in some cases, continue to chemically react and cause degradation in the yield of the processed wafers
162
. If wafers are degraded sufficiently, the potential financial loss associated with reduced yields can be significant.
Another problem with having a stagnant cassette environment
152
b
is that any particles that may have fallen onto the surfaces of the wafers
162
will continue to remain on the top surfaces of the wafer while the cassette rests in the cassette environment
152
b.
These particles
164
, in some cases can cause substantial damage to the semiconductor circuits formed on the wafers
162
. It is well known that it is undesirable to allow particles
164
to remain on the surface of the wafers
162
in between the processing operations. The longer the particles remain on the surface of the wafers
162
, the higher the probability that such particles will cause damage to sensitive integrated circuitry, and will be harder to clean.
Still another problem with having cassettes
160
sit in static environment
152
b
is that once a process engineer opens door
155
to remove the cassette
160
, the cassette
160
may expose the process engineer to potentially undesirable levels of toxic gasses
166
that emanate from the surfaces of the wafers
162
. In some cases, such exposure to process gasses and chemical by-products can cause process engineers handling such cassettes to become disoriented and thus potentially drop the cassette
160
full of valuable processed semiconductor wafers
162
.
In view of the foregoing, what is needed is an atmospheric transport module that is capable of controlling the environment in and around a cassette of wafers.
SUMMARY OF THE INVENTION
Broadly speaking, the present invention fills these needs by providing an atmospheric transport module capable of generating a mini-environment in a region where cassettes of wafers are temporarily stored during processing. The mini-environment is preferably configured to define an air flow through the wafers such that process gases and by-products are substantially purged away from the environment surrounding the wafers. It should be appreciated that the present invention can be implemented in numerous ways, including as a process, an apparatus, a system, a device, or a method. Several inventive embodiments of the present invention are described below.
In one embodiment, an atmospheric transport module is disclosed. The module has a housing and the housing includes a number of inventive elements. The housing has a top portion that contains a blower for generating a regulated air flow in a downward direction that is away from the top portion of the housing. A load cell region is also included and it is laterally offset from the blower. The load cell includes a shelf for supporting a wafer cassette and the shelf is separated from a wall of the load cell to thus define a redirection air flow slot. A perforate
Jacob David E.
Kaveh Farro F.
Larson Dean Jay
Maraschin Martin R.
Lam Research Corporation
Lu Jiping
Martine & Penilla LLP
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