Uniform precipitation of oxygen in large diameter wafers

Abstract

In the present stage of development, 300 mm crystals often contain a transition from vacancy-rich to interstitial-rich. Due to this radially varying concentration of intrinsic point defects, the radial size distribution of grown-in oxide precipitate nuclei is also inhomogeneous in these wafers. In order to achieve a radially uniform bulk defect density for internal gettering, a slow temperature ramp induced growth of all grown-in oxide precipitate nuclei is the appropriate procedure to overcome problems resulting from the inhomogeneous size distribution of grown-in nuclei. This approach is based on the observation that in contrast to the nuclei size distribution, the nuclei density distribution is homogeneous over the wafer, independent of the dominant intrinsic point defect.