CRYSTAL-GROWTH IN SILICON CHEMICAL-VAPOR-DEPOSITION FROM SILANE - THEROLE OF HYDROGEN

Authors
Citation
M. Tao et Lp. Hunt, CRYSTAL-GROWTH IN SILICON CHEMICAL-VAPOR-DEPOSITION FROM SILANE - THEROLE OF HYDROGEN, Journal of the Electrochemical Society, 144(6), 1997, pp. 2221-2225
Citations number
24
Categorie Soggetti
Electrochemistry
ISSN journal
00134651
Volume
144
Issue
6
Year of publication
1997
Pages
2221 - 2225
Database
ISI
SICI code
0013-4651(1997)144:6<2221:CISCFS>2.0.ZU;2-B
Abstract
Crystal growth mechanisms in chemical vapor deposition (CVD) of silane are studied in some detail. An atomic view reveals that the free ener gy change upon the formation of a small crystal on the (100) silicon s urface in Si-CVD from SiH4 is always negative, due to the presence of hydrogen. Therefore, nucleation and step growth are unnecessary, in co ntrast to crystal growth from melt. Epitaxial growth in this case take s place through iterative adsorption and desorption reactions on the p eriodic surface sites of the substrate. Slow desorption reactions resu lt in vacancies and distorted bond angles which hinder epitaxial growt h. Based on this model, the role of H desorption in low temperature Si epitaxy from SiH4 is investigated. A thermodynamic analysis implies t hat H desorption is the limiting factor to low temperature epitaxy in the pressure range of 1 to 760 Torr, and the pressure dependence of mi nimum epitaxial temperature is derived as T-epi(degrees C) = 106 log P -tot(Torr) + 668. Below 1 Torr, adsorption rate becomes the limiting f actor to low temperature epitaxy.