Ion energy distribution in NF/sub 3/ based process chamber cleaning discharges

Summary form only given. NF/sub 3/ based discharges are commonly used for cleaning residual silicon dioxide and nitride from plasma enhanced chemical vapor deposition (PECVD) process chambers. In order to find a balance between fast chamber cleans and overly aggressive cleaning chemistries, which can lead to premature hardware failure, a fundamental understanding of the physical and chemical characteristics of the discharge is required. For this reason, we have measured the ion energy distribution functions (IEDFs) and the relative concentration of the ionic and neutral species present within capacitively coupled parallel plate discharges operated with NF/sub 3/ diluted with either argon, helium, neon or oxygen. For reactor operation at a fixed power of 1.35 W/cm/sup 2/ and fixed NF/sub 3/ mole fraction of 25%, we found that when argon was used as the diluent, the principal ion present was Ar/sup +/ for all pressures investigated (0.5-1.5 Torr). In contrast, for similar reactor operating conditions using helium dilution, He/sup +/ concentration was relatively low, with NF/sub 2//sup +/, N/sub 2/F/sup +/, F/sup +/, F/sub 2//sup +/, and N/sub 2//sup +/ all having larger concentrations.