The observation of oxidation-induced stacking faults and extrinsic gettering in silicon using X-ray diffraction topography

Abstract

The generation and development of oxidation-induced stacking faults (OISFs) in silicon wafers during complementary metal-oxide-silicon (CMOS) device processing has been studied using anomalous transmission X-ray topography together with synchrotron radiation double-crystal reflection topography. A comparison of X-ray topographic methods for the observation of surface defects is made, highlighting the difficulties of imaging such defects and the particular advantages of anomalous transmission topography. The identity of the observed defects, namely faulted loops with Burgers vectors parallel to <111>, was confirmed from diffraction contrast. The distribution of the OISFs and their generation behaviour indicate that, in this case, nucleation occurred at surface precipitates of fast-diffusing contaminants, most probably metallic in nature. The localized elimination of stacking faults in the vicinity of dislocation arrays is shown, providing an X-ray topographic observation of extrinsic gettering, whereby stacking-fault nuclei are eliminated through the removal of metallic contaminants by dislocations.