SUPERSONIC MOLECULAR-BEAM SCATTERING AS A PROBE OF THIN-FILM DEPOSITION PROCESSES

Citation
Lq. Xia et al., SUPERSONIC MOLECULAR-BEAM SCATTERING AS A PROBE OF THIN-FILM DEPOSITION PROCESSES, Journal of vacuum science & technology. A. Vacuum, surfaces, and films, 13(6), 1995, pp. 2651-2664
Citations number
49
Categorie Soggetti
Physics, Applied","Materials Science, Coatings & Films
ISSN journal
07342101
Volume
13
Issue
6
Year of publication
1995
Pages
2651 - 2664
Database
ISI
SICI code
0734-2101(1995)13:6<2651:SMSAAP>2.0.ZU;2-V
Abstract
The reactions of silane, SiH4, disilane, Si2H6, and phosphine, PH3, on single crystalline Si(100) and Si(111) surfaces, and methylsilane, Si H3CH3, on a beta-SiC surface have been examined employing supersonic m olecular beam scattering. The emphasis here is not on any one experime ntal result, but rather on the specific experimental approaches adopte d and a selected set of results that serve to demonstrate the similari ties and differences between these systems and the more extensively st udied reactions occurring on transition metal surfaces. All reactions have been examined at substrate temperatures characteristic of steady- state thin him growth. Translational activation is observed to be an e fficient means to promote the reactivity of the group IV species: SiH4 , Si2H6, and SiH3CH3. In all cases, the reactivity increases exponenti ally with scaled incident kinetic energy, where the scaling analysis s pecifically takes into account the microcorrugation of the gas-surface potential in terms of how incident kinetic energy and angle of incide nce couple to determine the probability of dissociative chemisorption. The reaction probability of SiH4 is described quantitatively over a w ide range of reaction conditions by a recently published model that ad apts Rice-Ramsperger-Kassel-Marcus theory to translationally activated dissociative chemisorption. In contrast, PH3, due to its coordinative unsaturation, is found to react almost exclusively via a trapping-med iated precursor dissociation channel. By employing a novel analysis sc heme, the dependence of PH3 dissociative chemisorption on the fraction al coverage of both P(a) and H(a) has been deduced under conditions wh ere the desorption of H-2 and P-2 are finite. The experimental techniq ues described here, and the associated conclusions made in this work, should be of tremendous value in future studies directed at examinatio ns of the gas-surface chemistry involved in epitaxial thin film growth . (C) 1995 American Vacuum Society.