Suppression of self-interstitials in silicon during ion implantation via in-situ photoexcitation

摘要

The influence of in-situ photoexcitation during low temperature implantation on self-interstitial agglomeration following annealing has been investigated using transmission electron microscopy (TEM). A reduction in the level of as-implanted damage determined by RBS and TEM occurs athermally during 150 keV self-ion implantation. The damage reduction following a 300 C anneal suggests that it is mostly divacancy related. Subsequent thermal annealing at 800 C resulted in the formation of (311) rod like defects or dislocation loops for samples with and without in-situ photoexcitation, respectively. Estimation of the number of self-interstitials bound by these defects in the sample without in-situ photoexcitation corresponds to the implanted dose; whereas for the in-situ photoexcitation sample a suppression of (approx)2 orders in magnitude is found. The kinetics of the athermal annealing process are discussed within the framework of either a recombination enhanced defect reaction mechanism, or a charge state enhanced defect migration and Coulomb interaction.