Polycrystalline silicon formed by ultrahigh-vacuum sputtering system

Abstract

Using an ultrahigh-vacuum (UHV) sputtering system, we could grow two new methods of polycrystalline silicon films. The one is as-deposited polycrystalline silicon on glass at substrate temperatures under 500 °C. The other is solid-phase-crystallization by thermal annealing of as-deposited amorphous silicon films in a UHV. As-deposited polycrystalline silicon films were oriented to (220) and grain sizes were determined from half-width of x-ray diffraction to be about 40 nm. From the deposition temperature dependence of the x-ray diffraction peak intensity, the activation energy of the crystalline growth was calculated to be about 0.6 eV. Hydrogen atoms in the sputtering gas lower the reproducibility of as-deposited poly-Si. Polycrystalline silicon films produced by thermal annealing of as-deposited amorphous silicon films at 550 °C in UHV have a (111) orientation. Field-effect mobilities of the as-deposited polycrystalline silicon film and the polycrystalline silicon film by UHV thermal annealing were 5 and 18 cm2/V s, respectively.