Drying and gas or vapor contact with solids – Apparatus – With means to treat gas or vapor
Reexamination Certificate
2000-04-03
2001-03-20
Wilson, Pamela (Department: 3749)
Drying and gas or vapor contact with solids
Apparatus
With means to treat gas or vapor
C034S202000, C034S210000, C034S215000, C034S230000, C134S021000, C134S030000, C134S037000, C134S099100, C134S902000
Reexamination Certificate
active
06202318
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates generally to the field of semiconductor devices and semiconductor manufacturing methods, and more particularly to systems and methods for cleaning wafer-handling implements.
BACKGROUND OF THE INVENTION
The manufacture of semiconductor devices is a time consuming process that requires high levels of cleanliness throughout the many phases of the manufacturing process. Many steps of manufacturing are conducted in various classes of “clean rooms” having purified air flows to reduce the incidence of airborne particle contaminants to prescribed levels.
Clean rooms are typically designated in accordance with the number of permitted contaminants of a prescribed size per cubic foot of airspace. For example, much semiconductor manufacturing is presently conducted in Class
10
clean rooms, which have filtered air flows to permit no more than ten particles per cubic foot of up to 0.5 &mgr; in size. Nevertheless, wafers upon which the semiconductor devices are assembled can become contaminated, and therefore rendered defective, by contaminants that are introduced at various process steps. For example, contamination can arise from incomplete cleansing of reagents from the wafer handling apparatus, and the like.
The presence of contaminants can have a catastrophic impact on product yield, notwithstanding an otherwise proper and complete formation of the semiconductor device. Moreover, although the wafers themselves can be properly cleansed of reagents and the like that are used incident to various manufacturing steps, the wafer handling equipment, for a variety of reasons, may not be completely cleansed of the reagents and may therefore serve as a source of wafer contamination for subsequent batches of wafers.
SUMMARY OF THE INVENTION
According to an aspect of the present invention, a system for processing wafers and cleaning wafer-handling implements includes a work cell having a plurality of processing stations for processing wafers, a cleaning station for receiving and delivering wafers to and from a wafer cassette and cleaning a wafer cassette, a transfer mechanism for moving wafers between the plurality of processing stations and the cleaning station. According to an aspect of the invention, the cleaning station may include an exterior door, an exhaust, a housing forming an interior chamber, an interior door, and a plurality of gas nozzles for delivering a cleansing medium over a wafer cassette placed within the interior chamber.
According to another aspect of the present invention, a method for processing wafers and cleaning wafer cassettes is provided that may include the steps of delivering a wafer cassette containing wafers to a first station of a work cell, removing the wafers from the wafer cassette for processing, cleaning the wafer cassette after removal of all the wafers from the wafer cassette. According to an aspect of the invention, the step of cleaning the wafer cassette may include applying a pressurized stream of gas against the surfaces of the wafer cassette.
According to another aspect of the present invention, a method for processing wafers and cleaning a wafer cassette may include the steps of receiving a wafer cassette in a first work station of the work cell, cleaning the wafer cassette, and delivering wafers to the wafer cassette. According to an aspect of the present invention, the step of cleaning the cassette may include delivering a pressurized sweeping gas to the first station to impact the wafer cassette to remove any contaminants.
A technical advantage of the present invention is that it provides for the cleaning of wafer-handling implements while reducing the possibility of omission of cleaning by human operator oversight. Another technical advantage of the present invention is that otherwise idle processing time for a wafer-handling implement may be utilized to clean the implement. Another technical advantage of the present invention is that it may be built into existing loadlocks or work cells to minimize floor space requirements. According to another aspect of the present invention, the labor required for processing wafers and cleaning wafer-handling implements may be reduced.
REFERENCES:
patent: 5551165 (1996-09-01), Turner et al.
patent: 5698040 (1997-12-01), Guldi et al.
patent: 5711821 (1998-01-01), Turner et al.
patent: 5839455 (1998-11-01), Turner et al.
patent: 5991965 (1999-11-01), Stroh et al.
patent: 6055742 (2000-05-01), Kim
patent: 6098304 (2000-08-01), Manjkow et al.
Brooks Jimmie
Guldi Richard L.
Brady III Wade James
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
Wilson Pamela
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