John E Sheppard

US Patent:

44180950, Nov 29, 1983

Filed:

Mar 26, 1982

Appl. No.:

6/362578

Inventors:

Peter L. Young - North Wales PA
Barry F. Stein - Dresher PA
John E. Sheppard - Cornwells Heights PA

Assignee:

Sperry Corporation - New York NY

International Classification:

H01L 3924

US Classification:

427 63

Abstract:

The present invention teaches a method of planarizing built-up vacuum deposited surfaces or areas on Josephson junction and semiconductor devices so that successively deposited layers do not replicate the undulations of previous layers. After a surface layer is deposited in a vacuum system and part of the surface is etched, a raised surface is generated. A photoresist lift-off stencil is applied to the surface to be preserved and the material to be removed is removed by isotropically etching so as to leave an overhang or ledge of photoresist material over the area of the material retained. A new layer of material is now deposited by vacuum deposition so as to almost fill the area to be planarized. A small gap remains between the top of the new material being vacuum deposited and the botton of the photoresist stencil so that solvent can be introduced to the stencil. When the photoresist stencil is removed, the top of surface being preserved is substantially planar with the new layer of material.

US Patent:

45336245, Aug 6, 1985

Filed:

May 23, 1983

Appl. No.:

6/497364

Inventors:

John E. Sheppard - Cornwells Heights PA

Assignee:

Sperry Corporation - New York NY

International Classification:

G03C 500
G03C 516

US Classification:

430312

Abstract:

A novel multilayer lift-off pattern of positive and negative photoresist materials is provided. A positive first layer is deposited on a substrate and flood exposed before a subsequent layer of negative photoresist material is added on top of the positive photoresist material. An optional third layer of positive photoresist material may be added on top of the negative photoresist to provide the top layer. A window or aperture is provided in the top layer employing conventional mask, exposure and development techniques. The top of the bottom layer is plasma etched through the window or aperture so that the previously flood exposed bottom layer can be developed without affecting the layers deposited thereon. A deep undercut lift-off pattern is provided which is useful in the manufacture of Josephson junction devices employing low temperature metals as well as for the manufacture of semiconductor devices.