Method of forming detector array contact bumps for improved lift off of excess metal

摘要

An improved method of forming metal contact bumps for infrared detector array includes depositing a thick layer of positive organic photoresist, and exposing the entire layer to light. A second, substantially thinner layer of photoresist is then applied, and exposed with a pattern of light corresponding to the contact bumps desired. The photoresist is developed to resolve the pattern in the top thin film, and the underlying thick resist is isotropically developed down to the substrate surface and under a portion of the remaining unexposed top layer. the metal to form the contact bumps is then deposited, preferably by evaporative deposition. The overhanging edges of the top layer of photoresist prevent continuous metal step coverage between the surface of the photoresist layer and the bumps formed on the substrate surface in the cavity. The remaining photoresist is then dissolved, and the metal deposited on the surface of the second layer is readily removed.