Diffusion Bonding of Metal Wires Directly to the Functional Metal Oxide Semiconductors for Forming Reliable Electrical Contacts

Forming reliable ohmic contacts to the functional metal oxide semiconductors has always been problematic in fabricating sensors and actuators. The common practice is to establish wire bonds to the metallic films previously deposited/printed over or under the oxide layer. Here, we describe a method for the diffusion bonding of metallic wire segments directly to the oxide layer surface, and demonstrate the reproducible formation of contacts with reliable mechanical and electrical qualities. Bonding is made at elevated temperatures in the 350–500 °C range under die pressure. Bonding Pt, Au, Ag, Cu, and Al wires to SnO 2, TiO 2, and ZnO are demonstrated.