Chemical vapor deposition of NiSi using Ni(PF3)4 and Si3H8

NiSix films were deposited using chemical vapor deposition (CVD) with a Ni(PF3)4 and Si3H8/H2 gas system. The step coverage quality of deposited NiSix was investigated using a horizontal type of hot-wall low pressure CVD reactor, which maintained a constant temperature throughout the deposition area. The step coverage quality improved as a function of the position of the gas flow direction, where PF3 gas from decomposition of Ni(PF3)4 increased. By injecting PF3 gas into the Ni(PF3)4 and Si3H8/H2 gas system, the step coverage quality markedly improved. This improvement in step coverage quality naturally occurred when PF3 gas was present, indicating a strong relationship. The Si/Ni deposit ratio at 250 °C is larger than at 180 °C. It caused a decreasing relative deposition rate of Ni to Si. PF3 molecules appear to be adsorbed on the surface of the deposited film and interfere with faster deposition of active Ni deposition species.