Lift-off wafer processing

Claim 1

An improved process for depositing a metallization pattern on the surface of a semiconductor structure, said process comprising: applying a layer of a polyimide on the surface of the semiconductor, said polyimide being a copolymer of an aromatic cycloaliphatic diamine and a dianhydride consisting essentially of the recurring unit having the formula ##STR3## wherein Y is a divalent organic radical selected from carbocyclic-aromatic, aliphatic, araliphatic, cycloaliphatic, and heterocyclic radicals, combinations of these, and radicals with heteroatom-containing bridging groups where the heteroatom in the bridge is oxygen, sulfur, nitrogen, silicon or phosphorus, provided that, out of the total number of polyamide-imide recurring units, 1 to 100 percent of such units have Y equal to a phenylindane radical of the structural formula ##STR4## wherein R 1 is a hydrogen or lower alkyl, and R 2 , R 3 , R 4 and R 5 are independently hydrogen, halogen or lower alkyl, and either aromatic ring of the unsymmetrical phenylindane radical may be bonded to an amide or imide nitrogen; applying a barrier layer over the polyimide layer; applying a mask layer over the barrier layer; defining the desired metallization pattern in the mask layer; etching the barrier layer and polyimide layer to expose the surface of the semiconductor in a pattern which corresponds to the desired metallization pattern on the mask layer; metallizing the surface of the semiconductor which has been exposed by the etching; and removing the polyimide and barrier layers which remain by dissolving the polyimide layer in a substantially non-polar solvent.