Karen M Abrahamovich

US Patent:

43776337, Mar 22, 1983

Filed:

Aug 24, 1981

Appl. No.:

6/295477

Inventors:

Karen M. Abrahamovich - South Burlington VT
Clifford J. Hamel - Jericho VT
Edward H. Payne - Essex Junction VT
Dean R. Weed - South Burlington VT

Assignee:

International Business Machines Corporation - Armonk NY

International Classification:

G03C 504
G03C 500

US Classification:

430312

Abstract:

This describes different methods of using a single photoresist layer to define both metal contact vias and metal lift-off areas on semiconductor integrated circuits. The methods use positive photoresist containing a small amount of base such as imidazole to provide a lift-off overhang when the resist is exposed and developed to provide a reversal image. One method includes the steps of exposing selected regions of a layer of photoresist deposited on the surface of an integrated circuit, developing said image to remove the exposed photoresist to form a positive image, etching, exposing other selected regions of said photoresist layer to a negative image, baking the layer of photoresist to decarboxylate and fix the negative image in said layer of photoresist rendering all remaining unexposed regions of the said layer of photoresist, alkali soluble removing the alkali soluble regions of said photoresist, depositing metallurgy over the surface of the circuit and then removing the negative image formed in the layer of photoresist. A different method uses similar steps but in a different order. This second method first exposes and fixes the negative image which is not developed.