Influence of thermal history on the residual disorder in implanted silicon

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Abstract
Channeling effect measurements using MeV 4He ions were used in the study of the anneal of implantation disorder in Si. The Si was implanted at LN2 temperature with arsenic or boron to dose levels sufficient for the formation of amorphous layers. We found that the residual disorder depends upon the previous annealing procedures. Samples annealed directly at temperatures up to 950°C exhibited high levels of disorder. The measurements suggest that the disordered layers can contain regions misoriented at small angles to the original substrate. Samples with sequential anneals from 450 up to 950 in 100°C increments, were essentially damage free from channeling viewpoint. We suggest that this thermal history is responsible for of some of the conflicting viewpoints in the literature.