AVS 49th International Symposium
    Electronic Materials and Devices Wednesday Sessions
       Session EL+SS+SC-WeA

Paper EL+SS+SC-WeA8
Kinetics and Mechanism of Adsorption and Ultrathin Oxide Growth by Ozone on Si(100)2x1 and Si(111)7x7

Wednesday, November 6, 2002, 4:20 pm, Room C-107

Session: Semiconductor Film Growth and Oxidation
Presenter: K. Nakamura, National Institute of Advanced Industrial Science and Technology (AIST), Japan
Authors: K. Nakamura, National Institute of Advanced Industrial Science and Technology (AIST), Japan
A. Kurokawa, National Institute of Advanced Industrial Science and Technology (AIST), Japan
H. Nonaka, National Institute of Advanced Industrial Science and Technology (AIST), Japan
S. Ichimura, National Institute of Advanced Industrial Science and Technology (AIST), Japan
Correspondent: Click to Email
Ozone is one of the promising oxidants to synthesize an ultrathin oxide film on silicon surfaces for the near-future MOSFET because of rapid oxidation rate at low substrate temperature, negligible thickness of structural transition layers in the oxide film, etc.@footnote 1@ However, to control the thickness of an oxide film precisely and accurately,@footnote 2@ kinetics and mechanism of initial oxide growth must be clarified. Thus, in this paper, we discuss chemistry of adsorption and ultrathin oxide growth by ozone on silicon surfaces. Si(100)2x1 and Si(111)7x7 were exposed to highly concentrated (>80%) ozone gas and monitored by x-ray photoelectron spectroscopy (XPS) and second harmonic generation (SHG). Kinetic analysis has suggested that initial dissociative adsorption of ozone on Si(100)2x1 and Si(111)7x7 proceed with the mechanism of leaving only one oxygen atom on the surface and of desorbing the other two, possibly, as a molecular oxygen. This adsorption, in contrast to that of oxygen, was featured with structure-insensitive kinetics, no activation barrier for the dissociation, and high sticking probability close to unity. After the adsorption was completed, first three oxide layers were synthesized by random adsorption of oxidant species on each layer in the consecutive manner. The formation of three layers led to the further growth of an oxide film with ozone with linear growth kinetics, but not with molecular oxygen. Each of these initial ozone-oxide layers has distinctively different activation energy for its growth: they were estimated 0 eV, 0.34 eV, 0.68 eV, and 0 eV for first, second, third, and above fourth layers on Si(100), respectively, enabling accurate control of the thickness of an oxide film. @FootnoteText@ @footnote 1@K. Nakamura, S. Ichimura, A. Kurokawa, K. Koike, G. Inoue, and T. Fukuda, J. Vac. Sci. Technol. A 17 (1999) 1275. @footnote 2@K. Nakamura, A. Kurokawa, and S. Ichimura, Jpn. J. Appl. Phys. 39 (2000) L357.