Semiconductor device with high-temperature ohmic contact and method of forming the same

Abstract

A semiconductor device includes a semiconductor layer, prelayer, refractory layer, and conductive layer. The conductive layer includes an ohmic contact layer, and may also include a barrier layer, of a highly stable, low-resistance element or compound, such as Au or Ti, which is formed on the refractory layer. The refractory layer is a material that does not react with, or dissociate from, either the prelayer or the conductive layer when the semiconductor device is exposed to relatively high temperatures. The refractory layer material may be metal suicides, phosphides, or nitrides. The material of the prelayer is selected to minimize strain between the prelayer, the refractory layer and the semiconductor layer to provide a relatively strong bond between the refractory layer and semiconductor. The prelayer may be selected to provide relatively high current injection to the semiconductor, and may further form a low Schottky barrier height with the semiconductor. Effects from dissociation and/or diffusion of the materials forming the conductive layer to the semiconductor when the semiconductor device is exposed to temperatures above 350° C. may be reduced by employing the refractory layer and prelayer.