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 c ombines an ultrahigh vacuum (UHV) environment with rapid thermal chemi cal vapor deposition (RTCVD). The technique is referred to as UHV/RTCV D. Using Si2H6, B2H6, and H-2 as process gases, low temperature (T les s-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= 133.3 2 Torr) total pressure regime. Epitaxial growth was achieved on hydrog en passivated silicon surfaces without using a high temperature in sit u clean. Effect of the growth temperature on the generation lifetime o f the films grown on 4-11 OMEGA cm (100) silicon substrates was studie d at three different temperatures of 700, 750, and 800-degrees-C using the Zerbst technique. The epitaxial films were in situ doped with bor on to a doping level of 1-2 X 10(16) cm-3. Generation lifetimes, as hi gh as 400 mus, were measured with no strong dependence on the growth t emperature. Chemical purity of the films was studied using secondary i on mass spectroscopy, which indicated low oxygen and carbon levels on the order of 10(17) cm-3.