Threading dislocation evolution in mega-electron-volt phosphorus implantedsilicon

The effect of dose and energy on postannealing defect formation for high en ergy (mega-electron-volt) phosphorus implanted silicon has been studied usi ng etch pit studies and transmission electron microscopy (TEM). Previous wo rk has shown that after annealing there is a strong dependence of dislocati on density threading to the surface on the implanted phosphorus dose and en ergy. A superlinear increase in threading dislocation density (TDD) with im plant energy between 180 and 1500 keV is observed for a dose of 1x10(14) cm (-2). In addition as a function of ion fluence, there is a maximum in the t hreading dislocation density at a dose of 1x10(14) cm(-2) followed by a rap id decrease in TDD. Both the superlinear increase in TDD with increasing en ergy and the rapid decrease with increasing dose have been further investig ated by TEM. A TEM study of these higher doses revealed formation of a stro ng bimodal loop distribution with small loops averaging < 1000 Angstrom and large loops averaging around 1 mum in size. Over the dose range of 1x10(14 ) cm(-2) to 5x10(14) cm(-2), the superlinear decrease in TDD from 1x10(6) c m(-2) to < 1x10(4) cm(-2) coincides with the superlinear increase in small dislocation loops from below 1x10(6) cm(-2) to above 1x10(10) cm(-2). It is suggested that the homogeneous nucleation theory can explain many of the r esults. However, the chemical presence of phosphorus appears to also play a n important role in the formation of the small dislocation loops and possib ly threading dislocations. (C) 2001 American Institute of Physics.