Detection of oxygen by PEELS in ribbon-like defects of thermally aged CZ-Si

Abstract

Oxygen precipitation during post growth thermal annealing of CZ-Si has been a subject of practical and fundamental interest for several decades. Precipitation in the lower temperature part of the range, below about 1000K, where the products are small and metastable. is of highest interest at present. The recent general availability of HREM instruments with interpretable resolution limits of ∽0.25nm facilitated many imaging and diffraction investigations of low temperature precipitation reaction products during the past three years. Many metastable reaction products were observed, including ribbon-like defects (RLD’s) extended along [011] Si with habit plane variable between {001} and {311} Si. loopites. blobs, decorated dipoles and small features visible only in strain contrast thought to be nuclei for the larger amorphous SiOx precipitates observed after aging at higher temperature. The RLD’s contained a crystalline phase along their cores differing in structure from Si. This phase was first identified as coesite, a phase of SiO2 stable only under high pressure, but later the HREM results were reinterpreted as hexagonal Si. not involving oxygen. This controversy remains unresolved, and it was suggested that independent determination of the presence or absence of oxygen in RLD’s by electron energy loss spectroscopy may be the most useful method for its resolution. This note presents our first results.