Low-temperature (<450 °C), plasma-assisted deposition of poly-Si thin films on SiO2 and glass through interface engineering

Abstract

A low-temperature, two-stage process that employs interface engineering is investigated for deposition of poly-Si thin films on SiO2 and glass. In this two-stage process, film growth is separated into two regimes: (i) interface formation and (ii) bulk film growth. Interface formation (stage 1) was optimized for remote plasma enhanced chemical-vapor deposition (PECVD) of ultra thin (<100 Å) μc-Si films on the oxide. This layer acts as a seed template, providing ordered growth sites for the next stage of film growth. Bulk Si film deposition (stage 2) was then initiated on the seed template using remote PECVD process conditions shown to produce low-temperature (<450 °C), epitaxial-Si films on crystalline silicon substrates, so as to drive a transition to larger grain growth off of the seed crystals. Results showed that the seed layer had a dramatic impact on bulk film crystallinity. Films deposited without a μc-Si seed layer were amorphous, whereas films deposited using a seed layer, in conjunction with the appropriate second stage conditions, were highly oriented (220) poly-Si.