Material or article handling – Apparatus for moving material between zones having different... – For carrying standarized mechanical interface type
Reexamination Certificate
2001-03-30
2003-04-08
Joyce, Harold (Department: 3749)
Material or article handling
Apparatus for moving material between zones having different...
For carrying standarized mechanical interface type
C414S940000, C454S187000
Reexamination Certificate
active
06543981
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to semiconductor substrate processing equipment, and more particularly to providing a localized ultra-clean mini-environment for substrate processing.
2. Description of the Related Art
In the manufacture of semiconductor devices, processing equipment is highly automated in order to speed transfer between processing steps. To effect the automation, there exists a large amount of moving mechanical equipment such as robots and automated doors. Any moving mechanical equipment may be a particle generator. The generated particles can be deposited on a substrate in the proximate area of the moving equipment. In addition, the particles may become entrained in air patterns within the processing module, thereby becoming capable of being deposited on any wafers or substrates within the processing module. The generated particles can cause substantial damage to semiconductor circuits formed on the wafer. For example, the particles deposited on the wafer may be entrapped by a thin film deposited on the wafer in the next processing step and render the circuit useless through this latent defect.
Semiconductor processing equipment typically employs the use of slot valves for the transport of wafers between modules. The valve covers a slot, port, aperture, etc. that is provided in the wall of the interfaced chambers, thereby isolating the chambers when the door is in a closed position. When a wafer is being transferred between modules the door will open to allow for passage of the wafer. The valves have moving mechanical parts and compressible o-rings capable of generating particles. Additionally, the valves also have an added disadvantage in that they can be located in a static air flow environment of the storage facility or processing module. In such a case, particle density in static slow moving or recirculating air surrounding a particle generation source can quickly rise. Semiconductor devices on wafers exposed to such contamination levels are at risk to damage due to particle deposition.
FIG. 1A
depicts a typical semiconductor process cluster architecture
100
illustrating the various chambers of the architecture. 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
is coupled to an atmospheric transport module (ATM)
103
that interfaces with the clean room
102
. The ATM
103
typically has a region for holding cassettes of wafers and a robot that retrieves the wafers from 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
110
including an atmospheric transport module (ATM)
111
which includes a filter/blower
112
. The filter/blower
112
is configured to generate an air flow
114
in the ATM
111
. In addition, the ATM
111
is shown connected to the load lock
116
. Although this type of prior art ATM
111
is capable of transferring wafers
124
from the cassette
126
into and out of the load lock
116
quite efficiently, the air flow
114
has been intended to flush particles away from the area in close proximity to the slot valve
118
. However, mechanical or other design constraints may preclude achieving an optimum air flow in certain important regions of ATM
111
. As a result, the air flow pattern is not the downward sweeping action
114
, but rather more of a circular flow
124
or even a substantially static environment. Load lock
116
is isolated from ATM
111
by slot valve
118
making a seal
120
. For example, the seal
120
may be an o-ring type seal. The wafer path
122
proceeds through the area defined by the non-sweeping air flow pattern.
During the opening and closing of the slot valve
118
when the door opens and shuts against the seal
120
, particle bursts are generated through the contact of the seal and the door or other mechanically contacting surfaces. It can be appreciated that there is some pressure exerted against the seal by the slot valve in order to isolate the chambers on either side of the closed slot valve. In addition, particles trapped between the seal and the door may be released as the door opens. Therefore, the generated particles become entrained in the air flow patterns in the vicinity of the slot valve and can deposit themselves onto wafers traveling through or near the slot valve opening.
Any particles that have been deposited onto the surface of the wafer may remain on the wafer through its processing stage. These particles may cause defects in semiconductor circuits fabricated thereon, resulting in extra costs and lower yields. In some cases, the particles can migrate through an open slot valve door resulting in the potential contamination of both chambers. This problem is not limited to ATM
111
environments, but can also occur at any location where moving parts are in proximity to wafers or wafer transport paths, where off-gassing occurs and where the airflow is non-optimum. It can be appreciated that the processing equipment used in semiconductor manufacturing may include numerous moving mechanical parts capable of generating particle bursts. While the particle bursts may not be completely eliminated, the particles must be removed from the substrate path prior to the substrate moving through the vicinity of the particle burst so that the particles are not deposited on the substrate.
In view of the foregoing, what is needed is localized air flow augmentation to sweep any generated particles away from the substrate path and out of the processing module to eliminate particles from being deposited on substrates.
SUMMARY OF THE INVENTION
Broadly speaking, the present invention fills these needs by enhancing an ultra-clean mini-environment with localized air flow augmentation. The mini-environment is preferably configured to generate the air flow in a proximity region around a particle generating device. It should be appreciated that the present invention can be implemented in numerous ways, including as an apparatus, a system, a device, or a method. Several inventive embodiments of the present invention are described below.
In one embodiment, a transport passage for transport of a wafer between a first chamber and a second chamber is disclosed. The transport passage includes an air flow supply for directing air flow from a top region towards a bottom region of the first chamber. A moveable door for opening and closing an aperture is also included. The aperture is defined on a wall between the first chamber and second chamber and located between the top region and the bottom region of the first chamber. The aperture further defines a passage between the first chamber and the second chamber. A cowl defining an enclosure in a proximity region of the moveable door is also included. The cowl has a top portion that is more proximate to the top region of the first chamber and a bottom portion that is more proximate to the bottom region of the first chamber. A fan is disposed in proximity to the bottom portion of the cowl so as to augment air flow from around the proximity region at the moveable door and through the enclosure defined by the cowl.
In another embodiment, an air flow enhancer for creating a reduced particle mini-environment in a vicinity of a wafer presence is disclosed. The air flow enhancer has an air flow supply for directin
Halsey Harlan I.
Jacob David E.
Joyce Harold
Lam Research Corp.
Martine & Penilla LLP
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