Evolution of microstructure during annealing of low-dose SIMOX wafers implanted at 65 keV

The microstructural changes that occur during annealing of ultra-thin oxygen-implanted silicon-on-insulator have been studied using transmission electron microscopy (TEM), Rutherford backscattering spectrometry (RBS), and Auger electron spectroscopy (AES). Silicon substrates were implanted at 65 kev with a dose of 4.5 × 10¹⁷ O⁺ cm^-2, followed by annealing at various temperatures. TEM results show that the defects observed in the as-implanted material (stacking faults and {1 1 3} defects) were reduced after annealing at 900 °C for 2 h and were eliminated after annealing at 1100°C for 2 h. A continuous buried oxide (BOX) layer was formed after annealing at 1300°C for 6h. Numerous silicon islands were present in the BOX layer. The silicon islands can be traced to a precursor structure that developed at the implantation step. RBS results indicate that the crystallinity of the top Si layer is significantly restored after annealing at 1100 °C for 2 h and is completely restored after annealing at 1300°C for 6 h. It was also found through AES analysis that the redistribution of oxygen during annealing is initiated at 1100°C.