Effect of Germanium Codoping on the Grown-In Oxide Precipitates in Nitrogen-Doped Czochralski Silicon

The effects of germanium (Ge)-codoping at 10(18), 10(19), or 10(20 )cm(-3) level on the grown-in oxide precipitates in 10(14 )cm(-3) level nitrogen (N)-doped Czochralski (NCZ) silicon have been investigated. It is found that Ge-codoping enhances the formation of relatively larger grown-in oxide precipitates. However, such enhancement effect weakens with the increasing Ge-codoping concentration. On this basis, the effect of 10(18) cm(-3) level Ge-codoping on the near-surface denuded zone (DZ) and bulk microdefects (BMDs) associated with oxygen precipitation in NCZ silicon subjected to an anneal at 1100 degrees C for 4 h (1100 degrees C/4 h) has been paid close attention. Moreover, the sustainability of the DZ in the 1100 degrees C/4 h -annealed NCZ silicon subjected to a "copper decoration" or a rigorous oxygen precipitation anneal featuring a prolonged nucleation anneal has been addressed. Thus, it is technologically significant to learn that for the 1100 degrees C/4 h -annealed NCZ silicon, the 10(18) cm(-3) level Ge-codoping can remarkably increase the BMD density to better satisfy the requirement of internal gettering (IG) and also ensure the existence of a well-defined DZ. Finally, the mechanism underlying the effect of Ge-codoping on the formation of grown-in oxide precipitates in NCZ silicon has been tentatively elucidated.