Ti/W silicide gate technology for self-aligned GaAs MESFET VLSIS

Ti/W mixed metal contacts on GaAs shows instable Schottky diode characteristics with short annealing cycles at temperatures higher than 750°C due to metallurgical reaction between Ti/W and GaAs. Ti/W silicide contacts on GaAs, however, exhibit stable Schottky diode characteristics after annealing even above 850°C. This is supported by backscattering and secondary ion mass spectrometry profiles which show no evidence of reactions between Ti/W silicide and GaAs even after annealing at 850°C for 1 hour. This high-temperature stable Ti/W silicide has been successfully used for gate metallization of self-aligned enhancement and depletion GaAs MESFETs in fully-implanted 1024-bit GaAs fixed address static memory cell arrays.