Morphology of Oxygen Precipitates in RTA Pre-Treated Czochralski Silicon Wafers Investigated by FTIR Spectroscopy and STEM

We used STEM and FTIR to investigate the morphology and stoichiometry of oxygen precipitates in samples pre-treated by RTA at 1250°C subsequently annealed in the temperature range between 800°C and 1000°C. The morphology of the oxygen precipitates depends on the temperature of the subsequent annealing. Annealing at 800°C results first of all in the formation of three dimensional dendritic precipitates while during annealing at 900°C or 1000°C mainly plate-like and octahedral precipitates are formed. The absorption bands of the dendritic SiOx precipitates were identified and simulated based on effective medium theory. All regular plate-like and octahedral precipitates could be well fitted assuming x = 2.