SHALLOW, TITANIUM-SILICIDED P+N JUNCTION FORMATION BY TRIPLE GERMANIUM AMORPHIZATION

TiSi2 contacts were fabricated using self-aligned silicidation technology by ion-beam mixing with germanium. Shallow p+ n junctions of 170 nm depth with low leakage currents of 10 nA and an ideality factor of 1.08 could be formed by 13 keV boron implantation in silicided silicon substrates preamorphized by germanium implantation. For germanium amorphization, three implantation energies were chosen to check the influence of the overlap between implantation produced interstitial-rich and vacancy-rich areas on transient diffusion of the boron and on formation of end-of-range disorder. Using this triple germanium amorphization, end-of-range defect concentrations could be appreciably reduced compared to conventional substrate amorphization, leading also to improved electrical characteristics and to somewhat shallower junction depths.