Effect of silicon interstitials on Cu precipitation in n-type Czochralski silicon

The effect of silicon interstitials induced by the prior thermal oxidation at 900 degrees C for 2-50 min on copper (Cu) precipitation in n-type silicon has been investigated by means of transmission electron microscopy and optical microscopy. For the sample without the prior thermal oxidation, the Cu precipitates exhibited to be spherelike with induced stress, and they were preferentially delineated as the etching pits. On the other hand, for the samples with the prior thermal oxidation for more than 5 min, the Cu precipitate colonies, in which Cu precipitates with sizes of 10-20 nm assembled on and around the dislocations, formed with different depth profiles dependent on the oxidation time. Moreover, the Cu precipitate colonies were preferentially delineated as aggregated and individual rods. Phenomenologically, the formation mechanism and depth profile of Cu precipitate colonies were explained in terms of the effect of thermal oxidation induced silicon interstitials. (C) 2008 American Institute of Physics.