Catherine Phuong Ngo

US Patent:

49065521, Mar 6, 1990

Filed:

Feb 22, 1988

Appl. No.:

7/158427

Inventors:

Catherine M. Ngo - Woodland Hills CA
Leroy H. Hackett - Torrance CA

Assignee:

Hughes Aircraft Company - Los Angeles CA

International Classification:

G03C 516

US Classification:

430312

Abstract:

Well-defined metal lines of 0. 5 micrometers and less in width are produced on a substrate by photolithography, using a two layer photoresist process. The first resist layer, adjacent the substrate, is poly(methylmethacrylate) from about 0. 5 to about 1 micrometer thick, having a sufficient amount of an ultraviolet absorbing dye to prevent positive interference of light reflected from the surface of the substrate during exposure. The second resist layer is a polymer of naphthoquinone diazide, in a thickness of about 0. 5 to about 1. 1 micrometers. To achieve 0. 5 micrometer resolution of the metal line, the total thickness of the two resist layers is about 1. 5 micrometers; to achieve less than 0. 5 micrometer resolution, the total thickness of the two resist layers is about 1. 0 micrometer.

US Patent:

53342844, Aug 2, 1994

Filed:

Oct 12, 1993

Appl. No.:

8/134129

Inventors:

Catherine Ngo - Woodland Hills CA

Assignee:

Hughes Aircraft Company - Los Angeles CA

International Classification:

H01L 2100

US Classification:

156656

Abstract:

A surface (30) of a wafer of indium phosphide (22) is treated by first etching the surface (30) with an aqueous solution of nitric acid and ceric ammonium nitrate. A toughening solution of about 4 parts by volume of acetic acid, about 4 parts by volume nitric acid, and about 1 part by volume hydrobromic acid is prepared and mixed. The roughening solution is contacted to the etched surface (30) of the wafer of indium phosphide (22) for about 15 to about 30 seconds to roughen the surface of the indium phosphide. Reaction products may be removed from the surface in aqueous hydrofluoric solution, and metal may be deposited upon the toughened surface in a strongly adhering layer (28).