Near‐Surface Damage and Contamination after CF 4 / H 2 Reactive Ion Etching of Si

Abstract

Silicon surfaces which had been exposed to reactive ion etching have been characterized by x‐ray photoelectron emission spectroscopy, He ion channeling, H profiling, and Raman scattering techniques. Plasma exposure of a clean Si surface leads to the deposition of a thin (∼30–50Å thick) C,F containing film. The near‐surface region (∼30–50Å) of the Si substrate is heavily disordered (“amorphized”), as found by ion channeling and Raman scattering. A modified, less damaged Si region extends from about 30–50Å from the surface to a depth in excess of 250Å. This layer contains a high concentration (∼5 atom percent) of H as shown by hydrogen profiling techniques. From the observation of Si‐H and vibrational modes by Raman scattering, it has been shown that the H is bonded to the Si lattice. In ion scattering, the extended modified Si layer appears to cause a strongly enhanced background in the energy spectra. Results of Monte Carlo range calculations are reported and compared with the damage depth found experimentally.