DOPANTS EFFECTS ON THE INTERFACIAL REACTION BETWEEN CO AND STRAINED SI0.8GE0.2 LAYERS

Interfacial reactions of cobalt with differently doped Si0.8Ge0.2 laye rs epitaxially grown on silicon, during furnace annealing up to 600 de grees C, were compared. Undoped and highly boron- or antimony-doped Si 0.8Ge0.2 strained layers were used for this study. The analytical tool s employed were Auger electron spectroscopy, secondary ion mass spectr oscopy, x-ray diffraction, and transmission electron microscopy. Both dopants accumulate at the surface as a result of the interfacial react ion with Co but boron also remains trapped between the reacted Co mono silicide region and a thin Co-rich near-surface layer. In addition, th e boron-doped sample exhibits a large accumulation of Ge at the interf ace between the unreacted SiGe and the reacted monosilicide. The latte r effect is related to the loss of Ge from the unreacted SiGe layers o bserved after high-temperature annealing, the B-doped SiGe epilayer un dergoing the largest loss at 600 degrees C, while the Sb-doped epilaye r was only slightly affected. (C) 1998 American Institute of Physics.