The influence of deposition variables on LPCVD tungsten films deposited by the WF/sub 6//Si reduction reaction

In an effort to isolate and study the Si reduction of WF/sub 6/ by the reduction reaction 2 WF/sub 6/ + 3 Si → 2 W + 3 SiF/sub 4/ a systematic study of the influence of temperature, substrate doping, deposition time and variable flow rates of tungsten hexafluoride (WF/sub 6/) was conducted. The effect of varying these parameters on film thickness, layer resistivity, encroachment and adhesion was investigated. A set of operating conditions has been defined that yield stable, adherent, self-limiting films of -100A thickness that are free from encroachment. Film quality was found to be relatively insensitive to moderate variations in process parameters, a favorable indication in terms of process integration and manufacturability