A process and is described for forming a tungsten silicide layer on a semiconductor wafer in a deposition chamber which comprises mounting a wafer on a susceptor having a fixed outer diameter regardless of the diameter wafer thereon to be processed in said chamber, and flowing into a deposition chamber a mixture of gases, including dichlorosilane gas and a gaseous source of tungsten through a fixed gas inlet pattern formed in a fixed diameter inlet receptacle, whereby a constant gas flow will be maintained in the deposition chamber regardless of wafer diameter being processed to thereby provide uniform deposition conditions in the deposition chamber, independent of wafer diameter. In this manner the same showerhead is used for all diameters of wafers, and while the susceptor is changed with each size of wafer to be processed, to thereby provide a crown pattern on the susceptor corresponding to the diameter of the wafer being processed, the same outer diameter is used for each susceptor, thereby providing the same dimensioned gap in the same position between the outer edge of the susceptor and a baffle plate surrounding the susceptor, so that the gas flow patterns in the deposition chamber remain constant during deposition, regardless of wafer diameter.