Michael A Davison

US Patent:

61872164, Feb 13, 2001

Filed:

Aug 27, 1997

Appl. No.:

8/917982

Inventors:

Paul William Dryer - Gilbert AZ
Michael J. Davison - Mesa AZ
Ralph A. Dyrsten - Phoenix AZ

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

C03C 1502

US Classification:

216 95

Abstract:

A wet etch bath (61) holds a wet etchant (52) for etching a dielectric over a semiconductor substrate. The wet etch bath (61) has a tub (63) separated from a reservoir (64) by a wall (65). The tub (63) is filled with the wet etchant (52) to a height of the wall (65). The reservoir (64) is filled with the wet etchant (52) to a height less than the height of the wall. A pump (66) coupled to the reservoir (64) pumps the wet etchant (52) through an osmotic membrane degasifier (69) to the tub (63). Adding the wet etchant (52) to the tub (63) causes the wet etchant (52) to cascade over the wall (65) back to the reservoir (64). The osmotic membrane degasifier (69) reduces a concentration of a reactive agent in the wet etchant (52).

US Patent:

58246010, Oct 20, 1998

Filed:

Jun 30, 1997

Appl. No.:

8/885265

Inventors:

Patrick P. H. Dao - Chandler AZ
Paul William Dryer - Gilbert AZ
Ping-Chang Lue - Scottsdale AZ
Michael J. Davison - Mesa AZ
Terry Andrew Willett - Tempe AZ
Margaret Leslie Kniffin - Tempe AZ
Rita Prasad Subrahmanyan - Mesa AZ

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

B44C 122

US Classification:

438713

Abstract:

A sacrificial oxide etching solution of carboxylic acid and HF having a high etch selectivity for silicon oxide relative to polysilicon, metal, and nitride. The solution is useful in the fabrication of microstructures having integrated electronics on the same chip. A carboxylic acid anhydride can be added to this solution to substantially remove all free water so that the etch selectivity to metal is improved. One specific solution is formed by mixing acetic acid, acetic anhydride, and aqueous HF.

US Patent:

55935389, Jan 14, 1997

Filed:

Sep 29, 1995

Appl. No.:

8/537053

Inventors:

Michael J. Davison - Mesa AZ
Paul W. Dryer - Mesa AZ
Wendy K. Wilson - Mesa AZ

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H01L 21311

US Classification:

1566371

Abstract:

A wet etching process (10) etches sacrificial oxide on a substrate without damaging a polycrystalline silicon structure on the substrate. The etching process (10) includes dipping the substrate in a surfactant (11), submerging a portion of the substrate in a recirculating bath of the etchant while injecting an inert gas into the etchant (12) to purge the etchant of oxygen, rinsing the substrate in deionized water (14), submerging a portion of the substrate in a hydrogen peroxide solution (15), rinsing the substrate for a second time (17), and drying the substrate in isopropyl alcohol vapor (18). The inert gas injected into the etchant displaces oxygen dissolved in the etchant and protects the polycrystalline silicon structure from being etched.