Method for contacting a semiconductor component

Abstract

A metallization layer forming a bonding pad is formed on a diffused region of a semiconductor substrate for making electrical connection to the diffused region. A polysilicon layer of the same conductivity type as the diffused region is formed on the diffused region, overlapping onto sidewalls and peripheral portions of a silicon oxide mask. A two-layer metallization layer comprising a first nickel layer and an overlying gold layer covers the polysilicon layer. The semiconductor device is formed by diffusing an impurity into the upper surface of a semiconductor substrate using a silicon oxide mask. A doped polysilicon layer is formed on the diffused region, overlapping onto sidewall portions and extending up onto the silicon oxide mask layer. The substrate is immersed in a metal-plating electroless bath to form layers of nickel and gold on conductive portions of the substrate including on the polysilicon and on a face of the substrate opposite the polysilicon layer. The substrate is selectively etched to remove contaminants from the silicon oxide mask introduced during immersion in the electroless bath. The device is then annealed at a suitable temperature. With a plurality of devices formed on a single wafer, the wafer is scored and diced to separate the devices for individual packaging.