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Porous Morphology and Oxidation Kinetics in a-Si:H RF Sputtered by He/H2

Published online by Cambridge University Press:  26 February 2011

J. Shinar ,
R. Shinar ,
S. Mitra ,
M. L. Albers ,
H. R. Shanks  and
T. D. Moustakas
J. Shinar
Affiliation:
Ames Laboratory and Physics Department, Iowa State University, Ames, IA 50011
R. Shinar
Affiliation:
Hicroelectronics Research Center, Iowa State University, Ames, IA 50011
S. Mitra
Affiliation:
Ames Laboratory and Physics Department, Iowa State University, Ames, IA 50011
M. L. Albers
Affiliation:
Ames Laboratory and Physics Department, Iowa State University, Ames, IA 50011
H. R. Shanks
Affiliation:
Ames Laboratory and Physics Department, Iowa State University, Ames, IA 50011 Hicroelectronics Research Center, Iowa State University, Ames, IA 50011
T. D. Moustakas
Affiliation:
Corporate Research Laboratories, Exxon Research and Engineering Co., Clinton Township, Annandale, NJ 08801
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Abstract

a-Si:H films rf sputtered in 10 mT He and 0.5 mT H2, in contrast to those prepared in Ar/H2 or Xe/H2, exhibit port depositional oxidation when sputtered at power levels of 0.55 – 3.3 W/cm2 (100 – 600W). SEM measurements show that the morphology of the films evolves from a cracked, microcrystalline, glassy one at higher rf power levels to a porous one at low power levels. This trend is also correlated with a sharply increasing density of Si-H2 dihydride bonds at decreasing rf levels. Auger depth profiles of the oxygen concentration in the films agree with a diffusion controlled process of a source solute of O2 molecules into a semi-infinite solid solvent. Yet IR absorption measurements indicate that the oxygen is confined to the internal surfaces of the microvoids. The diffusion constant is a very sensitive functi n of the sputtering conditions. At low rf power levels, it is as low as 10−16 – 10−1 cm2 /sec at room temperature, but increases to ∼10−13 at 250 – 350°C.These results are discussed in terms of a porous network of microvoids, through which the O2 “squeezes” into the film.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 95: Symposium E – Amorphous Silicon Semiconductors--Pure and Hydrogenated , 1987 , 183
Copyright
Copyright © Materials Research Society 1987

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