Lower Temperature Deposition of Polycrystalline Silicon Films from a Modified Inductively Coupled Silane Plasma

An inductively coupled plasma (ICP) is successfully modified to deposit polycrystalline silicon (poly-Si) films on a glass substrate (<300°C) with SiH4 diluted by hydrogen. The modification includes a gas residence time control and a dielectric cover on an internal metal antenna. A metal antenna discharge in 2% SiH4 at a total pressure of 2.0 Pa results in a monotonically increasing deposition rate up to 0.4 nm/s with a decrease in the residence time to 18 ms. The dielectric-covered antenna makes the deposition rate two times higher than the metal antenna. The higher crystallinity of the deposited film is achieved with a lower residence time and/or a smaller percentage of SiH4, both of which decrease the deposition rate. For example, a 600W 0.3% SiH4 discharge by the dielectric cover antenna gives a poly-Si grain size of 140 nm from the X-ray diffraction (XRD) spectra and a crystallization factor of 0.98 from the Raman spectra.