Microstructural evolution of oxygen implanted silicon during annealing processes

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Beam interactions with materials and atoms, 1999, Vol.148 (1), p.311-316
• Main Authors: Ishimaru, M., Tsunemori, T., Harada, S., Arita, M., Motooka, T.
• Format: Article
• Language: English
• Subjects: EELS; Silicon-on-insulator structure; TEM; XPS
• ISSN: 0168-583X; 1872-9584
• DOI: 10.1016/S0168-583X(98)00773-3

Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and electron energy loss spectroscopy (EELS) have been employed to characterize the microstructures, oxygen distributions, and chemical bonding states of SIMOX (Separation by IMplanted OXygen) wafers. Silicon substrates were implanted at 550°C with 2 × 10 17 and 4 × 10 17 cm −2 180 keV oxygen ions, followed by annealing at various temperatures. EELS spectra indicated that the chemical bonding state between Si and oxygen changed at 1000°C anneal, though there was no appreciable change in the microstructures observed by TEM below 1000°C anneal. Above 1100°C, oxygen precipitates were preferentially formed around the peak positions of the defect and oxygen concentrations in the as-implanted samples. These precipitates aggregated to reduce the surface energy, and their size increased with temperature. After 1350°C anneal, a continuous buried oxide layer was formed in the higher-dose specimen, while the upper- and lower-precipitates remained separately in the lower-dose one. The XPS profiles did not change at the later stage of annealing processes in the 2 × 10 17 cm −2 sample, though the precipitates became larger in size. This suggests that the oxygen diffusion mostly occurs along the lateral direction but does not along the vertical one in this sample