Physical characterization of low defect SIMOX materials

The materials for this study were prepared at an oxygen dose ranging from 1.2×10¹⁸ to 1.8×10¹⁸ cm ^-2 with an implanter at a 14° angle with an energy of 200 keV. During the oxygen implantation, the wafers were kept between 580-620°C. After the final anneal, the thickness of the top silicon and the thickness of the buried oxide were measured with an optical reflectance spectral photometer. The thickness measurement agreed well with the cross-sectional TEM measurement for the wafers studied. From the cross-sectional TEM, other defects such as the precipitates of oxide in the top silicon and the silicon islands in the buried oxide were examined. Under certain conditions, SIMOX (separation by implantation of oxygen) materials without precipitates and silicon islands and threading dislocation density lower than 10⁴ cm^-2 were observed. Epitaxial growth of silicon on these annealed SIMOX was also investigated. It was found that thin epitaxial silicon films of very good quality could be grown with an in-situ low-temperature hydrogen baking at a lower pressure than that of the high-temperature hydrogen baking which had produced voids on SOI structures. Detailed characterization results of low-defect SIMOX materials and epitaxial silicon films on these materials is discussed