Oxide growth retardation induced by rapid thermal annealing in Czochralsky-grown silicon consequence on the efficiency and the stability of internal gettering of Cr

Abstract

The anomalies induced by rapid thermal annealing (RTA) on the behavior of oxygen and their consequences on the efficiency and the stability of internal gettering of chromium in Czochralsky-grown silicon have been studied. Deep level transient spectroscopy profiling of the electrically active Cr concentration on bevelled samples, transmission electron microscopy observations on cross-sectional specimens, oxygen precipitate density assessment by etch pits counting and interstitial oxygen concentration measurements using Fourier transform infrared spectroscopy are presented. We have observed that the metal precipitation is controlled by the oxygen precipitation, and established a correlation between the internal gettering efficiency and the morphology of oxygen precipitates after nucleation. Besides, we have shown that the thermal instability of metallic precipitates strongly depends on the size and the morphology of oxygen precipitates at the end of the gettering treatment. Finally, our results support the concept of ‘oxygen-precipitation gettering’ previously reported by Gilles and Weber in the case of iron [D. Gilles, E.R. Weber, Phys. Rev. Lett. 64 (1990) 196.], and suggest the involvement of a dynamic effect, linked to the metallic precipitate growth which is triggered by emission of interstitial silicon during the growth of the oxygen precipitates.