Etching a substrate: processes – Gas phase and nongaseous phase etching on the same substrate
Patent
1997-10-06
2000-04-25
Cain, Edward J.
Etching a substrate: processes
Gas phase and nongaseous phase etching on the same substrate
134 37, 156345L, 156345LC, 216 83, 216 84, B44C 122
Patent
active
060540621
ABSTRACT:
A method and apparatus agitates an etchant contained within a bath. A wafer is immersed in a bath containing an etchant that is continuously mixed by release of a gas, preferably nitrogen, into the bath at a sufficient flow rate to agitate the etchant and assure a robust and substantially uniform selective etching process. The apparatus comprises valve assembly that receives gas from a source of gas under pressure and controls the flow rate and release pressure of the gas. In addition, the valve assembly contains an on/off valve that, when turned on, releases gas for a predetermined time period. Accordingly, a single operation of the on/off valve releases gas for the duration of a single selective etching cycle. A dispersion plate receives the gas from the valve assembly for release into the bath. The released gas passes through the baffle distribution plate that distributes the gas throughout the bath. The flowing gas agitates the etchant and the amount of agitation is controlled by controlling the pressure and flow rate of the gas.
REFERENCES:
patent: 5464480 (1995-11-01), Mathews
patent: 5571375 (1996-11-01), Izumi et al.
patent: 5698046 (1997-12-01), Guldi et al.
patent: 5868898 (1999-02-01), Liu et al.
Calio Jeffrey C.
Hendrix Timothy
Yoshikawa Stephanie A.
Cain Edward J.
LSI Logic Corporation
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