DIFFUSION OF SON IMPLANTED BORON IN PREAMORPHIZED SILICON

Transient enhanced diffusion of boron in preamorphized and subsequentl y regrown Si was studied by secondary ion mass spectrometry (SIMS) and transmission electron microscopy (TEM). A comparison of 4 keV, 1X10(1 4)/cm(2) baron implants into crystalline and Ge+ preamorphized silicon was undertaken. Upon annealing the B+ implant into crystalline materi al exhibited the well-known transient enhanced diffusion (TED). In thi s case the peak of the baron distribution was relatively immobile and only B in the tail showed TED. In the second set of samples, the surfa ce was first preamorphized by a 180 keV, 1x10(15)/cm(2) Ge+ implant wh ich produced an amorphous layer 2300 Angstrom deep, which then was imp lanted with boron. After implantation the tail of the B distribution e xtended to only 700 Angstrom. Upon annealing, TED of the boron in the regrown Si was also observed, but the diffusion profile was very diffe rent. In this case the peak showed no clustering, so the entire profil e diffused. The time for the TED to decay was around 15 min at 800 deg rees C. TEM results indicate that the (311) defects in the end of rang e damage finish dissolving between 10 and 60 min at 800 degrees C. The se results indicate that for these Ge preamorphization conditions, not only do the end of range defects not block the flow of interstitials into the regrown silicon, the (311) defects in the end of range damage act as the source of interstitials. In addition, boron does not appea r to cluster in regrown silicon. (C) 1996 American Institute of Physic s.