Modeling of Internal Gettering of Nickel and Copper by Oxide Precipitates in Czochralski-Si Wafers

Abstract

A practical simulator for internal gettering (IG) of nickel and copper by oxide precipitates was developed in which the diffusion and reaction processes were included. In this simulator, the morphology of oxide precipitates was considered. It was found that the diffusion-limited model, which well explained Fe gettering, could not explain the reported experimental results of Ni and Cu gettering. IG of Ni and Cu contamination was analyzed to be reaction-limited. The simulator also showed that (i) a higher density of precipitates provides more efficient gettering sites than a low density of larger precipitates at a fixed amount of precipitated oxygen, and (ii) the precipitate morphology of platelet is more effective for IG than that of sphere at a fixed precipitate volume. Further, the oxide precipitates with high density of about should be prepared just below the device active region in rapid thermal anneal process. The present IG model was combined with the reported oxygen precipitation model. These models make possible to control the oxygen precipitation for optimized IG.