Ohmic contacts for microwave diodes

Abstract

Au-TiN-n/sup +/-Si and Au-Ti-Pd/sub 2/Si-n/sup +/-Si ohmic contacts were fabricated using thermal and magnetron evaporation onto n/sup +/-silicon substrates with various concentrations of free electrons. Diode test structures with such contacts were fabricated using photolithography. The effect of thermal annealing and /sup 60/Co /spl gamma/-irradiation on the I-V curves and stability of both contacts and test structures was investigated. The data obtained were compared to the results of mathematical simulation of both tight contacts and those with a SiO/sub 2/ interlayer. The calculations and experiments demonstrated that such tight low-resistance contacts with Schottky barrier based on palladium silicides are tolerant to short-term thermal annealing up to 600/spl deg/C and to /spl gamma/-irradiation in the 10/sup 2/ to 3/spl times/10/sup 5/ Gy total dose range.