Al-Si contacts formed by ion irradiation and post-annealing

Al-Si contacts have been formed by implantation of As ions through Al-Si interfaces followed by heat treatment at 400–500 °C for 10 min. The erosion of Si proceeds uniformly in contact areas at the sintering temperatures. Diodes using Al-Si contacts produced by this technique have been fabricated on thin n+ layers in p-type Si substrates with junction depths of 0.35 μm and contact areas of 5 μm2. The average leakage current per diode (with an approximate junction area of 14×26 μm2) is about 10−8 A, as compared to the leakage current of 10−5 A for diodes with Al-Si contacts prepared by sintering of Al on Si at 420 °C. We attribute the improvement to the uniformity of Si erosion after the interfacial oxide has been dispersed by ion irradiation.