Morphlogy of Oxide Precipitates in Silicon Crystals

Morphology of thermally induced oxide precipitates (SiOx, x=∼2) in Czochralski-grown Si crystals are investigated using transmission electron microscopy.When the annealing temperature is 800 and 900°C, morphology of oxide precipitates is of a sqare-plate having the {100} habit plane with 〈110〉 sides and a column-like structure in it.When the annealing temperature is 1000°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.