Nickel-based germanosilicide of n(+)-Si0.83Ge0.17 for various doping concentrations and rapid thermal annealing conditions

Abstract

A Ni/n(+)-Si0.83Ge0.17 germanosilicide process has been investigated to understand the influence of temperature and doping concentration on the evolution of sheet resistance and microstructures. After depositing Ni film on Si0.83Ge0.17 epilayer and annealing for silicide reaction, sheet resistance and surface roughness were analyzed by using a four-point-probe and scanning probe micrograph. Favorable-quality Ni/Si0.83Ge0.17 contact was observed after annealing at around 500 degrees C, but severe degradation occurred when the temperature was high, above 600 degrees C, and this became even worse in heavily phosphorus-doped 1.2 x 10(20) cm(-3) Si0.83Ge0.17. In order to solve an inappropriate reaction, multilayer metal structures of Ni/Pt and Ni/Ti were employed. We found that a multilayer structure with 1-nm-thick Pt interlayer presented significant advantageous properties for germanosilicide of n(+)-Si0.83Ge0.17 with low sheet resistance and smooth surface morphology.