Rapid thermal annealing of ion-implanted semiconductors

Abstract

Annealing of ion implantation damage (in the form of amorphous layers and/or the layers containing only dislocation loops) in silicon and gallium arsenide has been studied by electron microscopy techniques and the effects on dopant distribution have been investigated by Rutherford backscattering and secondary ion mass spectrometry techniques. The annealing of amorphous layers occurs by solid-phase-epitaxial growth and that of dislocation loops involves primarily loop coalescence as a result of conservative climb and glide processes. The annealing of isolated loops occurs primarily by a bulk diffusion process. Almost a ‘‘complete’’ annealing of displacement damage is possible for shallow implants provided loop coalescence does not lead to the formation of a crossgrid of dislocations. For deep implants, the free surface cannot provide an effective sink for defects as in the case of shallow implants. Dopant profiles can be controlled to less than 500 Å in layers having good electrical properties. The enhanced diffusion of dopants which is observed is probably due to entrapment of point defects in the annealing regions.