Method of forming crossover connections

摘要

Disclosed is a crossover fabrication technique which is compatible with interconnect metallization for thin film and hybrid circuits which comprises a layer of copper. In one embodiment, evaporated layers of Ti and Cu are used as the base layers to build up the crossover spacing layer. A nickel protective layer is formed over the evaporated layers and the interconnect metallization. A copper spacing layer is then formed over the nickel layer by plating. Pillar holes are etched over selected areas of the interconnect metal preferably using an etchant which removes both the copper spacing layer and nickel protective layer, followed by forming the gold crossovers. The remaining copper spacing layer is removed by an etchant which preferentially attacks copper, and the nickel protective layer and copper base layers are preferably removed by a single etchant.