OPTIMIZED DEPOSITION PARAMETERS FOR LOW-PRESSURE CHEMICAL VAPOR-DEPOSITED TITANIUM SILICIDE

A system and a process have been developed for the low pressure chemical vapor deposition (LPCVD) of titanium silicide. The authors report for the first time the optimization of LPCVD titanium silicide film properties against the deposition parameters, including the temperature, pressure, and SiH4/TiCl4 flow rate ratios. Smooth, reproducible, low resistivity (15-20 μΩ-cm) titanium silicide films have been deposited at a temperature of 730°C, a pressure of 67 mtorr, and a SiH4/TiCl4 flow rate ratio of 20/2. The as-deposited films did not require any post-deposition annealing to achieve this low resistivity. All the as-deposited films had a Si/Ti metal ratio of about 2 (determined by Rutherford backscattering spectroscopy). Within the Auger detection limit, no contamination was observed in the silicide films, and the films had uniform composition except for a transition region between the titanium silicide and the underlying polysilicon layers.