Impact of Ge implantation on the electrical characteristics of TiSi2 p(+)/n shallow junctions with an alpha-Si (or a poly-Si) buffer layer

A new technology for forming a titanium-silicide shallow junction by combining germanium implantation with an amorphous-silicon (or a poly-silicon) buffer layer has been proposed for MOSFET's, The use of a buffer layer between Ti and Si can avoid the consumption of bulk-silicon and the recession of TiSi2 film into the source/drain junctions during the silicidation process. In this study, the important role of germanium-implantation on the formation of TiSi2 contacted p(+)/n junctions was examined, After subsequent implantation of Ge+ and B+ into the TiSi2 film, samples were annealed at different temperatures to form p(+)/n junctions and C54-TiSi2. Since the penetration of titanium atoms was suppressed due to the germanium-implantation, the periphery leakage and the generation leakage was improved and TiSi2/Si interfaces were even smooth. Therefore, p(+)/n junctions with a very low leakage current (0.192 nA/cm(2) at -5 V) and an excellent forward ideality factor (n approximate to 1.002) can be obtained. From the secondary ion mass spectrometry (SIMS) analysis, the junction depth is 400 Angstrom.