Titanium disilicide formation on heavily doped silicon substrates

摘要

Titanium disilicide formation on heavily doped silicon substrates was investigated with sheet resistance measurements, elemental depth profiling, and transmission electron microscopy. As found in a previous study lsqb;H.K. Park, J. Sachitano, M. McPherson, T. Yamaguchi, and G. Lehman, J. Vac. Sci. Technol. A2, 264 (1984)rsqb;, the TiSi2growth rate depended on the dopant concentration. The growth rate was highest on undoped substrates, intermediate on heavily phosphorushyphen;doped substrates, and lowest on heavily arsenichyphen;doped substrates. However, the critical dopant concentration effect reported by Parketal. was not observed. The uniformity of the titaniumhyphen;silicon reaction was not seriously affected by heavy substrate doping. For heavily arsenichyphen;doped substrates (3.0times;1021As/cm3), TiAs precipitates formed at C49 TiSi2grain boundaries, and the C49hyphen;tohyphen;C54 transformation temperature increased to 850thinsp;deg;C. For heavily phosphorushyphen;doped substrates (1.0times;1021P/cm3), no phosphides were unambiguously detected, and the C49hyphen;tohyphen;C54 transformation temperature remained below 800thinsp;deg;C. Discrete blocking layers at the silicidehyphen;silicon interface, such as the native silicon oxide or a dopanthyphen;rich phase, did not cause the reduction in silicide growth. Thus, it is concluded that dopant and knockhyphen;on oxygen atoms in solid solution in both the silicide and the silicon retard TiSi2growth.