There is a great demand to fabricate polycrystalline silicon films at low temperatures. A metal-induced crystallization method can significantly decrease the crystallization temperature of amorphous silicon (a-Si). Metal thin films are generally deposited on a-Si by the physical vapor deposition method followed by crystallization at a temperature lower than 600°C. In this study, a faster and more inexpensive electroless Ni plating method was introduced. It was found that Si crystallinity increased with Ni plating time, but dropped when the time reached 10 min. When the plating time was less than 5 min, all of the poly-Si became needlelike with preferred orientation parallel to the substrate.

Polycrystalline silicon (poly-Si) films grown by ultrahigh-vacuum chemical vapor deposition (UHVCVD) system and then annealed by excimer laser at room temperature have been investigated for the applications in polycrystalline silicon thin-film transistors (poly-Si TFTs). The results showed that the grain size of the laser-annealed poly-Si film decreased with laser energy density when a lower laser energy density below 157.7 mJ/cm2 was used. At about the threshold laser energy density (∼134.5 mJ/cm2), the finest grain structure could be obtained due to the partial melting in the top layer of the film. When the energy density of the excimer laser was larger than the threshold energy density, the large grain growth was initiated. The largest grain structure could be obtained at ∼184 mJ/cm2, while its surface roughness was better than that of the nonannealed UHVCVD poly-Si films. The surface roughening was suggested to arise from the specific melt-regrowth process but not the rapid release of hydrogen or capillary wave mechanism derived from laser-annealed amorphous silicon. By use of the laser-annealed UHVCVD poly-Si films as the active layer, the fabricated poly-Si TFT exhibited a field-effect mobility of 138 cm2/V s, a subthreshold swing of 0.8 V/dec, a threshold voltage of 3.5 V, and an on/off current ratio of ∼106.

The high quality silicon oxide films were prepared by plasma-enhanced chemical vapor deposition (PECVD) using tetraethylorthosilicate (TEOS)-oxygen based chemistry. The O2- or N2O-plasma treatments were performed on the as-deposited films as an attempt to improve the properties of the TEOS oxide films. TEOS oxide film deposited at lower pressure had lower Si–OH content, less carbon impurity, and flatter surface, and hence had better electrical properties. Both O2- and N2O-plasma would decrease the oxygen content of the oxide film, which led the composition of the film to deviate from the stoichiometric SiO2. The O2-plasma treatment did not show the encouraging effect on the chemical structure and electrical properties of the TEOS oxide films. In contrast, the N2O-plasma treatment could be a promising means to improve the breakdown field and leakage current density of the TEOS oxide films, which was accomplished by the N2O-plasma effect to facilitate the passivation of dangling bonds, linking reaction of Si–OH bonds, nitridation reaction and densification of the amorphous silicon oxide network.