Gettering of mobile oxygen and defect stability within back-surface damage regions in Si

Abstract

Motion and gettering of oxygen into damage regions created by back-surface mechanical abrasion in Si has been investigated using transmission electron microscopy (TEM), scanning electron microscopy, secondary-ion mass spectrometry profiling and secondary-ion microscopy. Redistribution and gettering of oxygen have been detected along dislocation lines after annealing at 600 °C by both TEM and direct ion imaging. Subsequent annealing at 1050 °C produces additional gettering, SiOx nucleation, and a dramatic increase in dislocation-line density within the initial damage region. Secondary dislocation lines extending to a depth ≃ 40 μm are also generated by the two-stage anneal, resulting in additional gettering sites for oxygen and other impurities. In comparison, single anneals at 1050 °C produce rapid defect annihilation, oxygen outdiffusion, and loss of additional gettering efficiency.