LOW-TEMPERATURE SILICON EPITAXY IN AN ULTRAHIGH-VACUUM RAPID THERMAL CHEMICAL-VAPOR-DEPOSITION REACTOR USING DISILANE

Epitaxial silicon films have been deposited by a new technique which combines an ultrahigh vacuum (UHV) environment with rapid thermal chemical vapor deposition (RTCVD). The technique is referred to as UHV/RTCVD. Using Si2H6, B2H6, and H-2 as process gases, low temperature (T less-than-or-equal-to 800-degrees-C) and high throughput (growth rate >0.25 mum/min) processing have been achieved in the 90 mTorr (1 Pa= 133.32 Torr) total pressure regime. Epitaxial growth was achieved on hydrogen passivated silicon surfaces without using a high temperature in situ clean. Effect of the growth temperature on the generation lifetime of the films grown on 4-11 OMEGA cm (100) silicon substrates was studied at three different temperatures of 700, 750, and 800-degrees-C using the Zerbst technique. The epitaxial films were in situ doped with boron to a doping level of 1-2 X 10(16) cm-3. Generation lifetimes, as high as 400 mus, were measured with no strong dependence on the growth temperature. Chemical purity of the films was studied using secondary ion mass spectroscopy, which indicated low oxygen and carbon levels on the order of 10(17) cm-3.