Comparison of Iron Gettering Effectiveness in Silicon between Ion-Implantation-Induced Damage and Poly-Crystalline Silicon

Abstract

Iron gettering effectiveness in silicon was compared between poly-crystalline Si and ion-implantation-induced damage. B-doped Czochralski-grown Si wafers with/without poly-crystalline silicon on the backsurface were contaminated with 6×1012 Fe/cm3 and implanted with Si at 50 keV to a dose of 2×1013/cm2. The samples were annealed at a temperature ranging from 700 to 900°C to induce Fe gettering. Poly-crystalline Si was found to be a more effective gettering site than ion-implantation-induced damage and to prevent Fe from being gettered at ion-implantation-induced damage. We consider that the difference of gettering efficiency between ion-implantation-induced damage and poly-crystalline silicon is caused by the difference of the gettering mechanism. When there was no polycrystalline Si and Fe concentration exceeded the solid solubility limit at a given temperature, Fe atoms were gettered at ion-implantation-induced damage. Photoluminescence and deep-level transient spectroscopy measurements revealed that the ion-implantation-induced damage, which gettered Fe, produced a new deep level. We consider that the defects related to this deep revel contain Fe clusters.