Characterization of refractory W, WNx, and WSix films on GaAs using thermoreflectance measurements

Abstract

Thermal‐wave measurements have been carried out for characterizing refractory W, WN_x, and WSi_x films on GaAs substrates. Thermal‐wave signals from these films were measured as a function of annealing temperature up to 900 °C, together with four‐point probe measurements and x‐ray diffraction analysis. The thermal‐wave signals indicated a good linear relation to electrical resistivity, as shown in the cases of W and WN_x films formed by sputtering deposition. This relation was associated with the grain formation and growth of W and W₂ N microcrystals as the annealing temperature increased. It was found that the thermal‐wave measurement was a very sensitive method for detecting phase transformation and degradation at the metal‐GaAs interface, which were shown in the case of WSi_x films formed by low‐pressure chemical vapor deposition.