Thin Si film on a SiO2 membrane has been recrystallized by single-shot excimer laser. Since there is no substrate acting as a heat sink to the latent heat in the molten Si film, the heat flow can be reduced immensely and also controlled well to form a temperature gradient along the membrane, resulting in the lateral growth of large grains, more than 70 µ m in length and a few µ m in width. Two thin film transistors (TFTs) with the channels parallel and perpendicular to the grain boundary, were fabricated using the laterally grown poly-Si film. The parallel TFT showed the maximum field-effect mobilities of more than 600 cm2/Vs for electrons and about 300 cm2/Vs for holes.

Hydrogenated amorphous-silicon films have been deposited by the plasma-free chemical-vapor-deposition method using tetrasilane (Si4H10) at temperatures as low as 350°C. The film deposited at 350°C and 9 Torr had hydrogen content as high as 15 at.%, optical bandgap of 1.78 eV, logarithmic ratio of photoconductivity (at a light intensity of 100 mW/cm2 under AM1 conditions) to dark conductivity of 3.2, activation energy of 0.78 eV and the Urbach tail slope as small as 56 meV. Thin-film transistors have been fabricated using the film deposited at 350°C. The electron mobility was 0.6 cm2/V s under as-deposited conditions.

Silicon dioxide films were deposited in a parallel-plate electrode RF plasma-enhanced chemical vapor deposition (PECVD) system using hydrogen-free tetraisocyanatesilane (TICS) and oxygen. The deposition parameters were varied systematically, and the films were characterized by measuring infrared spectra, density, etch rate, refractive index, and current-voltage (I–V) and capacitance-voltage (C–V) characteristics, as well as by examining their annealing behavior. At 300°C and a TICS partial pressure ratio of 20%, a water-free and hydroxyl-group-free SiO2 film was obtained. The film density, BHF etch rate, refractive index, resistivity, and dielectric constant were 2.3 g/cm3, 330 nm/min, 1.46, 7×1015 Ω·cm, and 3.6, respectively. The film quality degraded and, simultaneously, the film absorbed moisture from the atmosphere with decreasing deposition temperature; however, the quality can be improved by reducing TICS partial pressure. SiO2 films could be deposited even at 15°C, and had a resistivity of about 1013Ω·cm. Infrared measurements showed that SiO2 films deposited from TICS/O2 contained less absorbed water than those deposited from hydrogen-containing source materials at the same deposition temperature.

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