Improvement to Bulk Oxygen Precipitate Density Necessary for Internal Gettering in Antimony Doped N/N+ Epitaxial Wafers Using the 3‐Step Technique and Ramped Nucleation

Abstract

The addition of a ramped nucleation cycle, just after an initial oxidation, is shown to greatly increase the precipitation of interstitial oxygen during simulated processing on N/N+ antimony doped epitaxial wafers. When used with fully processed wafers, the ramped nucleation improves internal gettering. Oxygen precipitate density and bulk stacking fault density achieved are about a factor of 100 higher when using ramped nucleation. These results indicate that N/N+ antimony doped epitaxial wafers have an intrinsic gettering capability as good as that of lightly doped material when using an activation cycle (initial oxidation) and subsequent ramped nucleation. A method for calculating bulk stacking fault density is presented. It is shown that, at high concentration (above 107 cm−3), the square of the bulk stacking fault length is inversely proportional to their density. This finding indicates that the growth of bulk stacking faults is limited by the supply of interstitial silicon generated in the bulk during oxygen precipitate growth.