Platinum Metals in Ohmic Contacts to III-V Semiconductors

Platinum metals, particularly platinum and palladium, are used extensively in low resistance, relatively stable and laterally uniform ohmic contacts made to semiconductor devices formed from Group III and V elements. Palladium is primarily utilised as one component of a multilayer metallisation structure, improving adhesion to the semiconductor, while platinum is commonly used as a diffusion barrier to minimise interdiffusion between metal and semiconductor components. This paper describes the roles of platinum and palladium in ohmic contacts, gives examples of their typical utilisation and outlines the design considerations associated with the formation of reliable ohmic contacts.