Silicon surfaces which had been exposed to a CF4/H2plasma have been characterized by x‐ray photoelectron spectroscopy, ellipsometry, He ion channeling, and H profiling techniques. Plasma exposure leads to the deposition of a thin (∼30 A˚ thick) C,F‐polymeric layer. Hydrogen and/or damage (displaced Si atoms) can be detected in the near‐surface region up to a depth in excess of 400 A˚ from the Si surface.