Structure of thin polycrystalline silicon films on ceramic substrates

The structure of polycrystalline silicon films with thickness of 10 mum, wh ich were deposited by thermal chemical vapor deposition on ceramic substrat es, was investigated. In this article we report results of silicon films de posited on SiA1ON, mullite, and alumina substrates. The type of substrate s trongly influences the stress and the texture of the films. In the silicon films deposited on SiA1ON substrate tensile stress is observed, while in th e films deposited on mullite and alumina substrates compressive stress is p resent. In all deposited films the observed stress is higher than the therm al stress, which has been determined from the differences in the thermal ex pansion coefficients of the film and substrate materials. We observe in the films grown on SiA1ON substrate that the total stress decreases with incre asing deposition temperature, which implies a reduction of the intrinsic st ress in the films. We ascribe the reduction of the intrinsic stress to a lo wer defect formation at higher deposition temperature. The silicon films ex hibit a preferential texture, which becomes more random at higher depositio n temperatures, We also observe that at higher deposition temperatures the grain size is larger and the crystal growth is columnar. We propose that th e observed structural coherence between the alumina substrate and the silic on film results in an epitaxial growth that is responsible for a good adhes ion of the film to the substrate. (C) 2001 Elsevier Science B.V. All rights reserved.