The Stability of Reactively Sputtered WNx Thin Films on III-V Semiconductors

WNX thin films were deposited at room temperature on (100) n-type GaAs substrates by rf reactive sputtering of a high purity W target in Ar/N2 gas mixtures. Deposition parameters such as the rf power, the ratio of gas flows, and the total pressure can be optimized for the preparation of uniform and low resistivity WNX thin films. The W:N ratio in the as-deposited WNX films was determined using Auger spectroscopy and the morphology was examined by scanning electron microscopy (SEM). The WNx/GaAs samples were subjected to rapid thermal annealing in an N2 atmosphere at temperatures between 400°C and 800°C. The thermal stability of these structures was examined using electrical measurements and Auger profiling. The results are correlated with the properties of as-deposited films and the influence of various processing parameters will be discussed.