Vacuum beam studies of fluorocarbon radicals and argon ions on Si and SiO2 surfaces

Abstract

Si and SiO2 were exposed to c-C4F8 with and without Ar+, and to a mixture of characterized CxFy radical and stable species with and without Ar+. The mixture of CxFy radical and stable species was created from c-C4F8 and Ar plasma and included CF, CF2, CF3, and various heavy CxFy species. The neutral fluorocarbon flux to Ar+ flux and the energy of the Ar+ were varied. During the exposure, etch/deposition rates were measured and the flux of CxFy species leaving the surface for various conditions were qualitatively determined. The following were observed: (1) c-C4F8 is an etchant with Ar+ bombardment; (2) the CF, CF2, and CF3 species flux cannot account for the observed mass increase during depositing conditions; (3) CF2 and CF3 species are net products during etching conditions; and (4) the flux of large CxFy species leaving the surface is smaller during etching conditions than for depositing conditions. These observations imply that large CxFy species play a significant role in the surface chemistry.