Selective deposition of TiSi₂ on oxide patterned wafers using low pressure chemical vapor deposition

Abstract

The selective deposition of titanium disilicide was investigated using a cold-wall, low pressure chemical vapor deposition (LPCVD) technique with silane and titanium tetrachloride as the silicon and titanium sources, respectively. In-situ hydrogen plasma effectively cleaned the silicon wafer surface for deposition of C54 TiSi₂ at 760‡ C with full selectivity. A new method using a plasma only at the beginning of the deposition of the silicide further decreased the temperature to 680‡ C without losing selectivity. The result was a fine grained film probably due to the enhanced nucleation rate of the silicide. Cross-sectional TEM studies showed that the silicide grew into the silicon substrate, suggesting significant silicon consumption. The silicon substrate, consequently, seems to play a major role in the silicide formation. Silane, on the other hand, plays a minor role as a silicon source but does act as a scavenger of HC1 in the gas or on the silicide surface.