Low-temperature (450°C) poly-Si thin film deposition on SiO2 and glass using a microcrystalline-Si seed layer

A low-temperature (450 degrees C), remote plasma-assisted CVD process for deposition of poly-Si thin films on SiO2 and Coming 7059 glass in which interface format ion is separated from bulk film growth has been developed. This approach is based on first depositing an ultra-thin (<100 Angstrom) microcrystalline-Si seed layer onto the oxide in order to provide nucleation sites at which low-temperature poly-Si film growth can be initiated. Conditions for poly-Si film deposition were optimized by using a low-temperature, remote plasma process that had previously yielded epitaxial growth of Si thin films on crystalline Si substrates. Microstructural characterization was performed on poly-Si films grown with different seed layer thicknesses, and additionally with exposure of this seed layer to a predeposition hydrogen plasma treatment. Results demonstrated that the seed layer thickness and surface morphology played a significant role in promoting crystallinity in the poly-Si overlayer. For example using deposition conditions that yielded epitaxial film growth on Si substrates, films deposited on un-seeded oxide substrates were amorphous, whereas those deposited using a seed layer were polycrystalline. This indicated that interfacial nucleation was the rate limiting step in promoting the low-temperature deposition of poly-Si thin films.