Si-rich surface layer of photochemically deposited silicon nitride
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The etching reaction of a photochemically deposited silicon nitride film with F2 has been observed in situ using polarization-modulation infrared spectroscopy and quadruple mass spectrometry. The infrared spectrum of the silicon nitride film before etching exhibited two bands at 1030 and 975 cm−1, arising from Si-N vibration. Exposure of the film at 423 K to F2 led to an intensity decrease of the lower-frequency band, while the higher-frequency band increased. Simultaneous mass analysis revealed that the etching products evolved into the gas phase were SiF4 and H2. However, a further admission of F2 resulted in a slight decrease in intensity of the 975 cm−1 band as well as a slight evolution of SiF4. These results strongly suggest the presence of a metastable Si-rich layer on the surface of the silicon nitride film prior to reaction with F2. Infrared measurements have also been made in the Si-H stretching region, the results of which are described and discussed.
KeywordsMass Spectrometry Nitride Infrared Spectroscopy Infrared Spectrum Silicon Nitride
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- 14.P. J. Zanzucchi, in “Semiconductors and Semimetals”, Vol. 21B, edited by J. Pankove (Academic, New York, 1984) p. 113 and references therein.Google Scholar