STUDY OF REACTIVE-ION-ETCHED SILICON BY A NOVEL ULTRASHALLOW DEPTH PROFILING TECHNIQUE

Silicon treated with reactive ion etching in a CHF3/O2 plasma has been characterize by x-ray photoelectron spectroscopy and surface charging spectroscopy, in conjunction with ozone oxidation and subsequent HF-etching for nanodepth profiling. It was found that the residual damage mainly consisted of, from the bulk to surface, 2 nm of defective silicon where the Fermi level was pinned, 0.5 nm of silicon mainly contaminated by silicon carbide, 1 nm of silicon compounds (fluorides, oxides, and carbide), and 5 nm of fluorocarbon. After the removal of this damaged region, the Fermi level became unpinned.