Character of defects at an ion-irradiated buried thin-film interface

In order to investigate the nature of defects produced by ion irradiation through a heterostructure, a silicon-on-insulator substrate with a buried SiO2 layer at a depth of similar to1.5 mum was irradiated. The implantation was done using 2 MeV Si-28(+) ions in the dose range of 0.2-1x10(16) cm(-2). The subsequent defect analysis was performed using the Au labeling technique. Besides the presence of an expected excess of vacancy-type defects in the Si overlayer (V-Si(ex)), an additional vacancy excess peak was observed at the frontside of the buried interface (V-Int(ex)). The V-Int(ex) is found to increase linearly with increasing dose of the high-energy implant. The presence of this V-Int(ex) peak near the interface is also predicted by the TRIM Monte Carlo code. Additional Monte Carlo simulations of damage production via high-energy implantation in Si/X-type structures show that the nature of the defects at the front Si/X interface can be changed from vacancy to interstitial-type by increasing the mass of atoms in the buried thin-film, X. These experiments provide quantitative verification of nonuniform defect production at an ion-irradiated buried interface in Si. (C) 2002 American Institute of Physics.