TISI2 SELECTIVE GROWTH IN A RAPID THERMAL LOW-PRESSURE CHEMICAL VAPOR-DEPOSITION SYSTEM

The aim of this work is to selectively deposit titanium disilicide films on silicon area vs. silicon oxide area through a new commercial RTLPCVD apparatus. As a preliminary study, we tested our deposition system by using the well-known polysilicon deposition process. By this way, we showed that the temperature homogeneity on a 4 in. wafer is quite satisfying, and that the growth rates are about ten times higher than those obtained by using a standard hot wall LPCVD system. Then, we studied the titanium silicide deposition-from either pure titanium tetrachloride or hydrogen-diluted titanium tetrachloride. As-deposited layers are well-adherent to the substrate and crystallized according to the C 54 structure. The resistivity ranges from 15-20-mu-OMEGA-cm and the selectivity on 8-mu-m wide-lines never fails. An anomalous substrate silicon etching is observed when pure titanium chloride is used but we show that hydrogen dilution inhibits this unwanted phenomenon. Chemical reactions are proposed to explain the silicide deposition and the unwanted formation of gaseous silicon species leading to this anomalous silicon etching when pure titanium chloride is used.