Germanium Implantation into Silicon: An Alternate Pre-Amorphization/Rapid Thermal Annealing Procedure for Shallow Junction Technology

Abstract

ABSTRACTGermanium implantation into Si was conducted to pre-amorphize the-si surface layer prior to a shallow/high dose (42 keV, 2 × 1015 cm−2) BF2 implant. Cross-sectional transmission electron microscopy showed that rapid thermal annealing (RTA) of the amorphous layer (without BF2 ) leaves defect-free material in the implanted region. Only a discrete layer of small (∼300Å) dislocation loops due to straggling ion damage was found to be present at a depth corresponding to the amorphous/crystalline interface. RTA of the amorphous layer with the BF2 creatpd a high density of uniformly. distributed fine defect clusters (∼50Å) in the surface region (0–500Å) in addition to the straggling ion damage. Boron and F profiles obtained by secondary ion mass spectrometry from the unannealed and rapid thermally annealed samples showed the presence of high concentrations of these impurities in the surface region where the fine defect clusters were observed. A comparison of the RTA behavior of the pre-amorphized surface layers (with or without BF2 ) produced by Ge and self-implantation is presented.