Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Patent
1981-08-24
1983-03-22
Downey, Mary F.
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making electrical device
430314, 430315, 430317, 430394, 430952, 1566611, G03C 504, G03C 500
Patent
active
043776337
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. The positive image is then exposed and developed to leave either unexposed resist or negative image exposed resist regions. The previously unexposed resist is rendered soluble in alkali developer and removed. Metal deposition and lift-off steps complete the method.
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IBM Technical Disclosure Bulletin, vol. 23, No. 5, 1980, p. 1839.
Abrahamovich Karen M.
Hamel Clifford J.
Payne Edward H.
Weed Dean R.
Downey Mary F.
International Business Machines - Corporation
Thornton Francis J.
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