SPONTANEOUS ETCHING OF SI(100) BY XEF2 - TEST-CASE FOR A NEW BEAM SURFACE EXPERIMENT

Citation
Mjm. Vugts et al., SPONTANEOUS ETCHING OF SI(100) BY XEF2 - TEST-CASE FOR A NEW BEAM SURFACE EXPERIMENT, Journal of vacuum science & technology. A. Vacuum, surfaces, and films, 12(6), 1994, pp. 2999-3011
Citations number
37
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physics, Applied","Materials Science, Coatings & Films
ISSN journal
0734-2101
Volume
12
Issue
6
Year of publication
1994
Pages
2999 - 3011
Database
ISI
SICI code
0734-2101(1994)12:6<2999:SEOSBX>2.0.ZU;2-Z
Abstract
An ultrahigh vacuum multiple-beam setup has been designed to study sur face reactions that are of importance in plasma etch processes. The se tup consists mainly of five beams (reactive neutrals, ions, electrons, CFx radicals, and photons) all of which can be focused on the same sa mple area, and a quadrupole mass spectrometer detecting only molecules desorbing from this area. Data are reported on spontaneous etching fo r the Si(100)/XeF2 system. Both the incident flux of XeF2 on the sampl e and the desorbing fluxes of SiFx products and nonused XeF2 were meas ured quantitatively. The reaction of XeF2, the production of SiFx spec ies and the accumulation of fluorine on the silicon surface were studi ed as a function of temperature (300-900 K) for XeF2 fluxes of 0.24 an d 1.04 monolayers/s. For the reaction probability of XeF2 an exponenti al increase with temperature from 11% at 300 K up to 50% at 900 K was found. The main product was found to be SiF4 at 300 K gradually becomi ng replaced by SiF2 at temperatures higher than 600 K. A remarkable re sult is the accumulation of a rather thick SiFx reaction layer on the etched surface. From thermal desorption spectra the fluorine content w as calculated to be 38 monolayers at 300 K decreasing rapidly for high er temperatures. This suggests that fluorine diffusion into the silico n bulk might be of importance in the etching process.