Sulfurization of SiO2 surface for polycrystalline silicon growth on SiO2/Si structure at 250 °C

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Abstract
A study of sulfurizing SiO2 surfaces for the growth of Si/SiO2/Si structures was done in the present work. The silicon film was deposited at 250 °C by plasma enhanced chemical vapor deposition. All of the deposited Si films with or without sulfur treatment were of amorphous phases with a H2/(SiH4+H2) flow ratio less than 92%. For those films deposited at the H2/(SiH4+H2) flow ratio of 92%, a transition amorphous Si layer appeared between the SiO2 and polycrystalline silicon films in those samples without sulfur treatment. No transition amorphous Si layer was present in the sample deposited with sulfur treatment, and the largest grain size of polycrystalline silicon was estimated to be around 500 Å. The polycrystalline phase was obtained in all the silicon films deposited on SiO2/Si substrate with a H2/(SiH4+H2) flow ratio larger than 92%. This technique would be applicable towards thin film transistor fabrication.