Method for forming patterned films utilizing a transparent lift-off mask

Abstract

A lift-off method for use in depositing thin films in the fabrication of integrated circuits which avoids edge tearing of the films. The method involves depositing an organic polymeric first masking material on a substrate, and forming on said material a layer of a polydimethylsiloxane resin material. The material, in turn, is covered by a second masking layer, preferably an organic polymeric resist material into which openings are placed in a selected pattern utilizing lithographic techniques. Then, conforming openings are placed in the underlying polydimethylsiloxane resin material and the openings are extended through the underlying resist material by successive reactive sputter etching steps to expose the substrate surface in the aforesaid selected pattern. The thin film to be deposited is then applied over the resulting structure; it is, thereby, deposited on the substrate in said openings. The final reactive sputter etching step affords edges in the openings through the resin material layer which overhang the edges in the openings through the first masking layer affording easy lift-off of the unwanted areas of the deposited film when the first masking layer is totally removed by application of solvent.