Preparation of ultrathin microcrystalline silicon layers by atomic hydrogen etching of amorphous silicon and end-point detection by real time spectroellipsometry

The etching of hydrogenated amorphous silicon (a-Si:H) in thermally generated atomic hydrogen has been investigated in detail, utilizing real time spectroellipsometry for characterization and end-point detection. When properly controlled, etching can yield ultrathin microcrystalline Si (μc-Si:H) films of relatively high density on virtually any substrate material. These films are unique in that their microstructure is established by the crystallization of the near-surface a-Si:H, rather than by the nucleation of crystallites on the substrate, as occurs for plasma-enhanced chemical vapor-deposited μc-Si:H films.