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Abstract: We have studied the epitaxial Si growth on 4-inch-(001) Si wafers by atmospheric pressure plasma chemical vapor deposition (AP-PCVD) using a porous-carbon electrode. Defect-free growth of epitaxial Si is confirmed in the temperature range 470–570 °C by transmission electron microscopy. High minority carrier generation lifetime (2.0 ms) is observed in the Si film grown at 570 °C with a rate of 0.35 μm/min. In situ H2 AP-plasma cleaning of the substrate surface is effective for eliminating O and C concentration peaks at the film/substrate interface. Effects of plasma heating and ion bombardment of the growing-film surface have been discussed. [Copyright &y& Elsevier]

Abstract: Using atmospheric pressure, very high-frequency (VHF) plasma, silicon carbide (SiC) films were formed on single-crystal Si(001) substrates from a hydrogen (H2) and methane (CH4) mixture. The H2/CH4 plasma etched the cooled surface of a Si-coated electrode, generating SiH n species, and transported them to the heated substrate surface with interactions with CH n species generated from the decomposition of CH4 molecules. By virtue of the carbonization of the substrate surface in the beginning of deposition, a (001)-oriented 3C–SiC film could be formed at a substrate temperature (T sub) as low as 300°C, although the film-forming reaction was more enhanced at the higher T sub due to the smaller etching rate of the growing SiC film by atomic hydrogen. At T sub = 130°C, however, the full crystallization of the film did not occur, resulting in the deposition of a polycrystalline 3C–SiC film with the poorer crystallinity. The optical emission spectra of the plasma revealed that the Si substrate was etched by atomic hydrogen in addition to the Si-coated electrode at 130°C. [Copyright &y& Elsevier]

High-rate growth of epitaxial Si films at low temperatures by atmospheric pressure plasma chemical vapor deposition has been investigated. Si films are deposited on (001) Si wafers in gas mixtures containing He, H2 and SiH4 at substrate temperatures ranging from 530 to 690 °C. The films are characterized by reflection high-energy electron diffraction, atomic force microscopy and cross-sectional transmission electron microscopy. High quality Si films with excellent crystallinity and surface flatness similar to or better than those of commercial Si wafers are grown in the area where the deposition gap between the substrate and rotary electrode is small. Especially, in epitaxial Si film grown at 610 °C with an input plasma power of 2000 W, no lattice defects are observed by transmission electron microscopy. The maximum growth rate is approximately 6.6 μm/min at 690 °C with 1500 W and 1.2 μm/min at 610 °C with 2000 W, which is approximately 20–30 and 4–6 times faster than that obtained by thermal chemical vapor deposition at approximately 1100 °C, respectively. [Copyright &y& Elsevier]

Abstract: Hydrogenated amorphous silicon (a-Si) and microcrystalline silicon (μc-Si) films were grown in atmospheric-pressure (AP) He/H2/SiH4 plasma excited by a 150-MHz very high-frequency (VHF) power at a temperature of 220°C. The variations in thickness and crystallinity of the deposited Si films along the gas flow direction were studied as functions of gas residence time in the plasma, VHF power density and H2 flow rate. Furthermore, the electrical characteristics of bottom-gate thin film transistors (TFTs) were investigated to evaluate the film quality. The results revealed that the chemical reactions both in gas phase and on the growing film surface were significantly enhanced in AP-VHF plasma, promoting phase transition from amorphous to microcrystalline in a time of the order of 0.1ms. The performance of the TFTs showed that a-Si layers formed in the upstream portion of the plasma zone had reasonably good electrical property (field-effect mobility of approximately 2cm2/Vs) despite very high deposition rates around 20nm/s. While μc-Si layers deposited in the downstream portion were very defective, which might come from the insufficient passivation of grain boundaries with a-Si tissues due to a too long gas residence time in the plasma. The precise control of gas residence time by adjusting the length of plasma will be effective for the phase control of Si films with desired quality. [Copyright &y& Elsevier]

Abstract: Low refractive index silicon oxide films were deposited using atmospheric-pressure He/SiH4/CO2 plasma excited by a 150-MHz very high-frequency power. Significant increase in deposition rate at room temperature could prevent the formation of dense SiO2 network, decreasing refractive index of the resulting film effectively. As a result, a silicon oxide film with the lowest refractive index, n =1.24 at 632.8nm, was obtained with a very high deposition rate of 235nm/s. The reflectance and transmittance spectra showed that the low refractive index film functioned as a quarter-wave anti-reflection coating of a glass substrate. [ABSTRACT FROM AUTHOR]

Abstract: Using the atmospheric pressure plasma chemical vapor deposition (AP-PCVD) technique, SiC films were fabricated from the gas mixture of He, H2, SiH4 and CH4 on silicon substrates. High-power-density condition was adopted to sufficiently activate the reactive gas molecules in the plasma. The structure, composition and crystallinity of the films were investigated as functions of the H2 concentration in the gas mixture and substrate temperature. It was shown that increase in H2 concentration in the plasma atmosphere reduced the growth temperature of polycrystalline SiC film. As a result, polycrystalline 3C–SiC film of which grain size was of the order of 10 nm could be grown at a substrate temperature of 820 K with a deposition rate of approximately 6.7 nm/s. It was suggested that atomic hydrogen generated with addition of H2 in the gas mixture considerably affects not only the reaction process at the film-growing surface but also the form of precursors in the atmospheric pressure plasma. The results indicated the possibility of realizing the columnar growth of large 3C–SiC grains on Si substrate when the H2 concentration and the VHF power were simultaneously increased in the AP-PCVD process. [Copyright &y& Elsevier]

Abstract: Silicon nitride (SiN x ) films have been prepared at extremely high deposition rates by the atmospheric pressure plasma chemical vapor deposition (AP-PCVD) technique on Si(001) wafers from gas mixtures containing He, H2, SiH4 and N2 or NH3. A 150 MHz very high frequency (VHF) power supply was used to generate high-density radicals in the atmospheric pressure plasma. Deposition rate, composition and morphology of the SiN x films prepared with various deposition parameters were studied by scanning electron microscopy and Auger electron spectroscopy. Fourier transformation infrared (FTIR) absorption spectroscopy was also used to characterize the structure and the chemical bonding configurations of the films. Furthermore, etching rate with buffered hydrofluoric acid (BHF) solution, refractive index and capacitance–voltage (C–V) characteristics were measured to evaluate the dielectric properties of the films. It was found that effective passivation of dangling bonds and elimination of excessive hydrogen atoms at the film-growing surface seemed to be the most important factor to form SiN x film with a dense Si. The C–V curve of the optimized film showed good interface properties, although further improvement was necessary for use in the industrial metal–insulator–semiconductor (MIS) applications. [Copyright &y& Elsevier]