Strain reduction in the Si overlayer for improved SIMOX material

Damage and strain in high-dose O-implanted Si was studied systematically with Rutherford backscattering spectrometry and double-crystal X-ray diffraction. In the Si overlayer, compressive strain is the result of an implantation-induced vacancy excess. The depth of the compressive strain maximum is a function of O ion dose: at low doses the strain increases from the surface to the amorphous-crystalline interface, while at high doses relaxation through dislocation formation is observed when the compressive strain exceeds about 0.5%. After dislocation formation, the compressive strain maximum moves nearer to the surface. Strain reduction can be achieved with either high (4.2 MeV) or low (0.1 MeV) energy Si implantation to increase or decrease respectively the local vacancy excess. The former results in strain relaxation through dislocation formation while the latter reduces strain through the introduction of compensating interstitials.