Rapid thermal annealing of dopants implanted into preamorphized silicon

Abstract

The rapid thermal annealing behavior of BF+2 and As+ +BF+2 implanted into crystalline and preamorphized silicon is studied. After solid phase epitaxy nearly complete electrical activity is obtained without channeling tails (for the preamorphized silicon) or significant thermal diffusion. Dislocation loops always appear near the amorphous-crystalline (α/c) interface of the preamorphized layer after solid phase epitaxy annealing (called ‘‘deep disorder’’). For preamorphization using Si+ damage into room-temperature silicon targets, dislocations also span between the deep disorder and the surface, called ‘‘spanning dislocations.’’ The spanning dislocations are eliminated by preamorphization using Ge+ implanted into room-temperature silicon targets. Transmission electron microscopy studies show the spanning dislocations move to the surface under thermal treatment, while the deep disorder remains to act as a getter region. The deep disorder is shown to getter F, or Au when Au is intentionally diffused from the wafer backside. The same kind of disorder correlates the limited diffusion behavior of B for BF+2 implants into crystalline Si. Otherwise, for the cases studied, the secondary ion mass spectrometry and Rutherford backscattering spectrometry profiles show nearly normal diffusive behavior for B or As dopants for 10-sec rapid thermal anneal. General physical interpretations are noted.