BEHAVIOR OF INTRINSIC SI POINT-DEFECTS DURING ANNEALING IN VACUUM

Using B and Sb doped Si(100) doping superlattices (DSL) as tracers of native Si point defect behavior it is shown that vacuum annealing at 810 degrees C leads to a depletion of Si self-interstitials, with their smallest concentration at the surface, but does not affect the vacancy population. At a fixed depth, the interstitial concentration drops for increasing annealing times; for a given time, the interstitial concentration increases into the sample as a function of depth. Inert anneals of a B-DSL in Ar show flat interstitial profiles. Apparently, the vacuum anneal makes the surface a better sink for interstitials than an inert Ar anneal, leading to an equilibrium interstitial concentration below the value in the bulk and establishing a net outflow of interstitials to the surface. The absence of a response of the vacancy population yields a lower limit on the interstitial-vacancy recombination time of 10(4) s at 810 degrees C. Process simulation of this scenario captures the essential trends of the experimental data. (C) 1995 American Institute of Physics.