Fabrication of High Quality Poly-Si From Fluorinated Precursors

Poly-Si thin films with grains 100–200 nm in dia. showing a highly ordered texture were grown from fluorinated precursors, SiFnHm (n+m=3), on a glass substrate at 300–400 °C with the aid of atomic hydrogen. According to the in situ observation by ellipsometry, the reconstruction was undergone in a solid phase stimulated by impinging atomic hydrogens within a thin layer of about 10 nm thick owing to the strong chemical interaction of the pair of H and F in Si-network. Both H and F were released efficiently from the network to the levels of 2 × 1020 cm−3 and (2−5) × 1019 cm−3, respectively. Dangling bonds were also efficiently passivated down to 4 × 1016 cm−3 with hydrogens diffused through the network. P-doped films showing electrical conductivity of 10−2 S/cm (300 °K) with the activation energy of 0.24 eV was obtained by alternately repeating the deposition of thin layer and the treatment with atomic hydrogens.