Interfacial modification of amorphous substrates for microcrystalline silicon growth with in situ hydrogen plasma pretreatment

Abstract

Microcrystalline silicon (pc-Si:H) films have been deposited onto hydrogenated and amorphous Si-rich silicon nitride and thermal oxide substrates with silane (SiH4)-hydrogen (H,) in remote plasma-enhanced chemical vapor deposition (RPECVD) at 250 degrees C, and these films have been investigated. It is found that in situ hydrogen plasma pretreatment of the amorphous substrates prior to pc-Si: H deposition is effective in reducing the interfacial amorphous transition region. It is believed that this hydrogen plasma pretreatment gives adsorption and nucleation sites by breaking weak Si-N and Si-Si bonds and also removes native Si-O-x and hydrocarbon impurities. In the case of SiNx:H surface, surface roughening from atomic hydrogen etching and surface cleaning effects are greater than those for stable thermal oxide. Surface crystallization at the initial stage of the growth can be obtained on amorphous substrate at low temperature without an a-Si transition layer. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.