Timothy N Hendrix

US Patent:

60540621, Apr 25, 2000

Filed:

Oct 6, 1997

Appl. No.:

8/944247

Inventors:

Jeffrey C. Calio - Concord CA
Stephanie A. Yoshikawa - Palo Alto CA
Timothy Hendrix - San Jose CA

Assignee:

LSI Logic Corporation - Milpitas CA

International Classification:

B44C 122

US Classification:

216 57

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.