Refractory metallizations on GaAs FET’s

Abstract

Refractory metal FETs utilizing the laser annealed refractory α-metal silicide gates and ohmic contacts have been fabricated on MBE grown material. The RF Magnetron sputtering technique for the deposition of the α-refractory metal silicides by rotating the substrates over two separate targets has shown the following advantages over sputter deposition from a single target: (1) overall average composition can be better controlled by varying the power, gas flow, partial pressure and substrate-target distance, (2) amorphous films, which are desirable as diffusion barriers, are always obtained because α-Si is deposited on each pass of the target, and (3) because the substrate spends only a small time near the sputter target as it rotates, the surface temperature remains lower than if a single sputtering target were used and thus photoresist can be employed to lift. 1.0μm long gates. A comparison is made between various silicide fabrication techniques and evaluation of the performance for differrent compound concentrations in as far as resistivity and specific contact resistance are concerned. An all refractory metallized GaAs FET was fabricated to demonstrate the feasibility of the methods discussed.