LOW-TEMPERATURE SELECTIVE SILICON EPITAXY BY ULTRA-HIGH-VACUUM RAPID THERMAL CHEMICAL-VAPOR-DEPOSITION USING SI2H6, H-2 AND CL-2

We present the use of the Si2H6/H-2/CL(2) chemistry for selective sili con epitaxy by rapid thermal chemical vapor deposition (RTCVD). The ex periments were carried out in an ultrahigh vacuum rapid thermal chemic al vapor deposition reactor. Epitaxial layers were grown selectively w ith growth rates above 150 nm/min at 800 degrees C and 24 mTorr using 10% Si2H6 and H-2 and Cl-2 with a minimum Si:Cl ratio of 1. Excellent selectivity with respect to SiO2 and Si3N4 was obtained indicating tha t very low Cl-2 partial pressures are sufficient to preserve selectivi ty. In situ doping results with B2H6 show that sharp doping transition s and a wide range of B concentrations can be obtained with a slight B incorporation rate reduction with Cl-2 addition. Our results indicate that UHV-RTCVD with the Si2H6/H-2/Cl-2 chemistry yields highly select ive Si epitaxy with growth rates well within the practical throughput limits of single wafer manufacturing and with a potential to reduce th e Cl content below the levels used in conventional SiH2Cl2 based selec tive epitaxy processes. (C) 1996 American Institute of Physics.