MICROSTRUCTURE AND STOICHIOMETRY DEPENDENCE OF ION-BEAM NITRIDES AS A FUNCTION OF ENERGY AND TEMPERATURE - A COMPARATIVE-STUDY BETWEEN SI AND SIGE

The microstructure and stoichiometry of nitrides formed by direct low-energy ion beam nitridation has been investigated as a function of ion energy and substrate temperature for Si(100) and SiGe/Si(100) films. Cross-sectional transmission electron microscopy, Rutherford backscattering spectroscopy combined with ion channeling and in situ x-ray photoelectron spectroscopy were used. It was established that a substrate temperature of 700 K produces a homogeneous amorphous nitride layer, whereas lower substrate temperatures decrease the incorporation of nitrogen in the film, while causing the formation of a nitrogen-poor amorphous layer beneath the nitride film. The N-to-Si or N-to-(Si + Ge) atomic ratio is found be close to 1.33 at 1 keV and decreases with ion energy. Effects due to chemically enhanced physical sputtering of germanium are observed.