Dislocations induced by bubble formation in high energy He implantation in silicon

He+ ions were implanted into a (111) epitaxial n-type silicon wafer at 1.6 MeV and at a dose of 2x10(16) cm(-2). After implantation the samples were subjected to thermal annealing at 800 degreesC for 30 min. Cross section transmission electron microscopy (TEM) was used to characterize microstructural features of the induced defects. Even in the as-implanted samples the TEM observations revealed the formation of a buried layer containing a dense array of bubbles. After annealing, a large band of defects (bubbles, Frank dislocation loops) was observed as well as rows of prismatic punching related dislocations which can extend over several micrometers away from the buried layer. Planar clusters of helium bubbles, lying on the {001} planes, were also observed and were supposed to be involved in the generation of dislocation loops in the matrix. Their nucleation is discussed in terms of the trap-mutation process. (C) 2001 American Institute of Physics.