Epitaxial growth of heavily B-doped SiGe films and interfacial reaction ofTi/B-doped SiGe bilayer structure using rapid thermal processing

The low-temperature epitaxy of heavily B-doped Si1-xGex films has been carr ied out by rapid thermal chemical vapor deposition (RTCVD) using Si2H6, GeH 4 and B2H6 in an H-2 carrier gas. The B concentration in the films increase s proportionally with increasing B2H6 partial pressure. Moreover, a high do ping level of 3.6 x 10(21) cm(-3) was achieved at a growth temperature of 5 00 degrees C. In the case of x = 0.25, the strain within the deposited film s measured by double crystal X-ray diffraction (XRD) decreases with increas ing B content, which can be directly related to the decrease of the lattice constant by B incorporation to the substitutional lattice site. The substi tutional B concentration estimated from the strain appears to be saturated at about 5 x 10(20) cm-(3). Furthermore, the interfacial reaction of a Ti/B -doped SiGe bilayer structure by rapid thermal annealing (RTA) and B redist ribution around the Ti germanosilicide layer have been examined. It was fou nd that, after RTA, a pileup of B atoms occurs at the C54-Ti(SiGe)(2)/Si in terface and an abruptness of the C54-Ti(SiGe)(2)/Si interface for the Ti/B- doped SiGe is superior to that for the Ti/undoped SiGe. These results indic ate that segregated B atoms at the interface cause a suppression of interfa cial reaction of Ti/SiGe, which leads to an abrupt C54-Ti(SiGe)(2)/Si inter face. (C) 2000 Published by Elsevier Science S.A. All rights reserved.