Copper precipitation in nitrogen-doped Czochralski silicon

Copper (Cu) precipitation behaviors in $p$-type conventional Czochralski (CZ) and nitrogen-doped Czochralski (NCZ) silicon have been comparatively investigated by means of transmission electron microscopy and optical microscopy. Within the CZ silicon, the Cu precipitates exhibited as spheres with size of about 100 nm and generated stress in the matrix. In this case, they were preferentially delineated as etching pits. On the other hand, within the NCZ silicon, the Cu precipitates were revealed as colonies in which spherelike Cu precipitates with sizes of 10–30 nm assembled on and around the climbing dislocations. As a result, they were preferentially etched as aggregated rods. The formation of Cu precipitate colonies in NCZ silicon was explained in terms of the effect of large grown-in oxygen precipitates on Cu precipitation.