Improvement of the morphological stability of Ni-silicided Si_(0.8)Ge_(0.2) layers by using a molybdenum interlayer

摘要

We have investigated the effect of a Mo interlayer on the structural and electrical properties of Ni-silicided Si_(0.8)Ge_(0.2) samples. It is shown that the samples with the interlayers give lower sheet resistances than the samples without the interlayers when annealed at temperatures in the range of 450-800℃. Glancing angle x-ray diffraction results show that regardless of the interlayers, only the Ni germanosilicide phase is formed across the whole temperature range. Scanning electron microscopy results show that the samples with the interlayers remain stable without serious surface degradation up to 600℃. It is further shown that the samples without the interlayers experience abnormal oxidation at a fairly low temperature of 500℃, while the interlayered samples remain stable without significant oxidation up to 800℃. The Mo interlayer is found to move toward the surface region, when annealed at temperatures in excess of 450℃. It is shown that the addition of the Mo interlayer effectively improves the thermal stability of the Ni-silicided Si_(0.8)Ge_(0.2) layers.