Visualization of vacancy type defects in the RP/2 region of ion implanted and annealed silicon

Abstract

Recently, a strong metal gettering in Si after ion implantation and annealing has been detected at depths between the surface and the mean projected ion range R P ( R P/2 effect), indicating the presence of residual defects therein. These defects are ascribed to excess vacancies generated in the R P/2 region by the ion implantation process. So far, the defects at R P/2 have been considered to be too small to be visible by transmission electron microscopy (TEM). We show that the crucial point for visualization of the vacancy-type defects at R P/2 by TEM is the specimen preparation technique. The very widely used conventional ion-milling technique for TEM specimen preparation introduces damage on the surface of the XTEM specimen, which blurs the original defect structure at R P/2 and obscures it from visualization. Only TEM specimens prepared by cleaving reveal cavities at R P/2. Minimum damage production caused during the preparation of the TEM specimen allows the imaging of the cavities at R P/2.