MORPHOLOGY OF OXIDE PRECIPITATES IN SILICON-CRYSTALS

Morphology of thermally induced oxide precipitates (SiOx, x = approximately 2) in Czochralski-grown Si crystals are investigated using transmission electron microscopy. When the annealing temperature is 800 and 900-degrees-C, morphology of oxide precipitates is of a square-plate having the {100} habit plane with [110] sides and a column-like structure in it. When the annealing temperature is 1000-degrees-C and the oxide precipitation rate is fast, the direction of dendritic growth is [100] in the Si matrix and top of the branch has a [110] facet. When the oxide precipitation rate is slow, the direction of the dendritic growth is [110]. These precipitates are amorphous SiO2. Their morphology is determined by either of these formation mechanisms: the Si matrix prescribes the shape of the precipitates (Si matrix negative crystal mechanism), or the interstitial oxygen grows to plate-like precipitates on the dislocations.