Amorphous silicon nitride deposited by hot-wire chemical vapor deposition

High-quality amorphous silicon nitrides were deposited by hot-wire chemical vapor deposition using SiH4, NH3, and H-2 gases. These films show a high deposition rate of 5 Angstrom/s, a low processing temperature of 300 degreesC, an excellent conformal coverage, a low etching rate of 7 Angstrom/min, an index of refraction of 2.1, an optical band gap of 4.0 eV, and a high breakdown field of 3 MV/cm. The effects of hydrogen dilution, substrate temperature, chamber pressure, and filament temperature on silicon nitride film property were studied to optimize the process. We found that adding H-2 to the processing significantly enhances the silicon nitride films' properties. The N content in the film increased significantly based on the infrared measurement. Hydrogen dilution is believed to play a key role for the conformal silicon nitride film. Hydrogen dilution also improves the process in that the gas ratio of NH3/SiH4 has been greatly reduced with the assistance of the H-2 gas. With substrate temperatures varying from 23degrees to 400 degreesC, this study showed a best film at near 300 degreesC. However, a good-quality silicon nitride can be grown even if starting with a substrate at room temperature. Furthermore, we found that increasing chamber pressure and a high filament temperature result in higher deposition rate and better quality in the films. The optimized films were grown with hydrogen dilution at about 300 degreesC substrate temperature, 83 mTorr pressure, and 2100 degreesC filament temperature. (C) 2004 American Institute of Physics.