Novel approach to defect etching in thin film silicon-on-insulator
A new etch process involving three sequential etch steps was developed to measure low defect densities in a range of about 1E3-1E8/cmü. The main advantages of this approach as compared to earlier methods are independence from the defect density, improved simplicity, and better image contrast. Resulting structures are similar to those obtained during defect etching in bulk silicon and allow the application of automatic defect measurement tools extending measurement ranges and accuracies to the bulk technology level. Dependences of defect densities on the implanted oxygen dose and implantation energy have been studied for SIMOX wafers. The experiment shows an increase of defect density with the dose and a decrease of defect density with the implantation energy. A comparison with transmission electron microscopy results shows good agreement.