Microstructural evolution and defects in ultra-thin SIMOX materials during annealing

The microstructure of ultra-thin SIMOX depends strongly on implantation dose, energy and annealing conditions. We used TEM combined with AES and RBS to determine the microstructural evolution of SIMOX wafers subjected to various temperatures during annealing. We found that an optimum dose window to produce a continuous buried oxide layer without Si islands is 3.0-3.5×10¹⁷ O⁺/cm² for 100 keV. The thickness of the silicon overlayer and BOX layer produced in this dose window was about 170 nm and 75 nm respectively. RBS analysis showed that a high quality crystalline Si layer was produced after annealing at 1350°C for 4 hrs. The defect density was very low (> 300/cm²) for all samples implanted at 100 keV.