日本金属学会誌

J. Japan Inst. Metals, Vol. 54, No. 2 (1990),
pp. 193-200

Diffusion of Oxygen Molecules in Amorphous Silica Thin Films

Masahiro Susa1, Hideyuki Shinohara2, Kazuhiro Nagata1 and Kazuhiro S. Goto1

1Department of Metallurgical Engineering, Faculty of Engineering, Tokyo Institute of Technology, Tokyo
2Graduate Student, Tokyo Institute of Technology, Tokyo. Present address: The Yasuda Fire and Marine Insurance Company, Limited, Tokyo

Abstract:

The diffusivities of O2 molecules in amorphous SiO2 thin films were determined over the temperature range of 1073 to 1273 K by means of the thermal oxidation of Si substrates. The SiO2 films were synthesized on Si substrates with the four different methods, i.e., thermal oxidation, sputtering, chemical vapor deposition (CVD) and spin-on glass (SOG) methods.
The difference of the manufacturing methods changed the diffusivities and the activation energies. The diffusivity in the thermally-grown SiO2 films was determined to be 6.4 × 10-13 m2/s at 1273 K, which was the same with that in the sputtered SiO2 films. On the other hand, the diffusivities in the CVD- and the SOG-SiO2 films were determined to be 9.1 × 10-13 and 1.1 × 10-12 m2/s, respectively. The activation energies were calculated to be 113 kJ /mol for the thermally-grown and the sputtered films, 83 kJ /mol for the CVD films and 59 kJ/mol for the SOG films.
FT-IR (Fourier-transform infrared spectroscopy) spectra revealed the following. Both before and after the oxidation Si-H bond was observed in the CVD films. On the other hand, in the SOG films Si-(CH3)3 bond was observed.
The difference of the structures of the four SiO2 films was estimated as follows. The thermally-grown and the sputtered films are consisted of the continuous random network of SiO2. But in the CVD- and SOG-SiO2 films the random network structure is partially terminated with Si-H and Si-(CH3)3 bonds, respectively, which increases the mean dimensions of the unit cell of the network.


(Received 1989/9/22)

Keywords:

diffusivity, structure, oxygen, silicon dioxide, silicon, thin film, thermal oxidation, sputtering, chemical vapor deposition, spin-on glass


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