Dependence of Grown-in Defect Behavior on Oxygen Concentration in Czochralski Silicon Crystals

The behavior of grown-in voids in the as-grown state and during annealing was investigated for Czochralski silicon wafers using an atomic force microscope, Secco etching and an optical precipitate profiler. In previous reports, most grown-in voids have been found to consist of two octahedrons. In this report, it was shown that the percentage of the voids which consist of one octahedron increased as the oxygen concentration decreased. The annealing behavior of the voids was summarized as follows. In the case of supersaturated oxygen concentration, growth of the oxide films within the voids occurred and this reduced their ability to form flow patterns during Secco etching. The growth of oxide films within the voids was enhanced by excess interstitial silicon atoms injected during annealing in an oxygen ambient. In the case of undersaturated oxygen concentration, the annihilation of the voids was also enhanced due to the injection of interstitial silicon atoms during annealing in an oxygen ambient. Interstitial silicon atoms contributed to both of these phenomena.