INVESTIGATION OF CF3I AS AN ENVIRONMENTALLY BENIGN DIELECTRIC ETCHANT

In this study, trifluoroiodomethane (CF3I), a non-global-warming gas, has been investigated as a substitute for typical PFC's currently used in wafer patterning and CVD chamber cleaning processes. Dielectric fi lms consisting of plasma enhanced chemically vapor deposited silicon d ioxide and silicon nitride were comparatively etched in CF3I and C2F6/ O-2 plasma environments. The etch rate of these films was ascertained as a function of applied rf power, etchant gas flow rate, reaction cha mber pressure, and CF3I:O-2 ratio. Destruction efficiencies of CF3I at different processing parameters were evaluated. Depending on the flow rate, rf power, and chamber pressure, utilization efficiency of CF3I varied from as low as 10% to as high as 68%. CF4, C2F6, COF2, and CO2 were the predominant by-products found in the exhaust stream; however, their concentrations were very low compared to the traditional proces s employing C2F6/O-2 mixtures.