In situ phase-modulated ellipsometry study of the surface damaging process of silicon under atomic hydrogen

We employed in situ phase-modulated ellipsometry in the monitoring of surface damage to monocrystalline silicon (Si) under plasma conditions typical for the chemical vapor deposition of diamond. Single-wavelength kinetic and spectroscopic ellipsometry measurements were done and complemented with Raman spectroscopy, in order to characterize the surface conditions. It was found that heating the Si substrate to 700°C in the presence of molecular hydrogen produces etching of the native oxide layer. When the hot bare silicon surface is submitted to atomic hydrogen, it becomes rough in minutes. Modeling of the spectroscopic ellipsometry provided a quantitative physical picture of the surface damage, in terms of the roughness layer thickness and void fraction. The results indicate that by the time a thin film starts to grow on these silicon surfaces, like in the chemical vapor deposition of diamond, the roughness produced by the atomic hydrogen has already determined to a large extent the rough nature of the film to be grown.