Surface reactions in Si chemical vapor deposition from silane

Abstract

The kinetics and mechanisms of silane adsorption and decomposition on clean single crystal Si surfaces have been investigated under ultrahigh vacuum conditions. Individual reaction steps are studied experimentally in the surface temperature range - 163–500 ºC, and modeling results are extrapolated to Si film growth temperatures (400–1000 °C) for comparison with the literature. Static secondary ion mass spectrometry (SSIMS) has been used to identify the silicon hydride species formed by silane adsorption on both the Si(100)-(2X 1) and Si( 111)-(7x 7) surfaces. Temperature programmed desorption of H2 has been used to measure the SiH4 reactive sticking probability (S) as a function of hydrogen coverage (@H). Kinetics of SiH3, SiH2, and SiH decomposition are compared here, and direct evidence for SiH decomposition as the rate-determining surface step leading to Si film growth is presented. The experimental data provide a firm basis for kinetic modeling of the growth of Si films from SiH4 by chemical vapor deposition (CVD). Preliminary modeling results are outlined here, including predictions of Si growth rate versus surface temperature (compared with data from the literature). © 1990, American Vacuum Society. All rights reserved.