WSi sub x Refractory Metallization For GaAs MESFETs.

WSi sub x thin films on GaAs substrates have been investigated for potential use as refractory gates for self- aligned MESFET and SDHT devices. Films with Si/W ratio in the range of 0.19- 1.76 have been dc magnetron co-sputtered. The deposition parameters were optimized to produce adherent films with low stress and minimal impurity content. In order to serve as a refractory gate the WSi sub x film should perform as a diffusion barrier. The optimal film which satisfied this requirement was found to have a S/W ratio of 0.45. This film yielded the highest crystallization temperature of 875C. Such a film remained amorphous following the high temperature dopant activation annealing (800C) and prevented Ga and As outdiffusion and pit formation in GaAs under the gate.