Trap centers in the Si-SiO2 interface region of MOS structures doped by ion implantation of gold have been investigated using constant capacitance deep level transient spectroscopy (CC-DLTS). Gold doses of 1012−3 × 1013 cm−2 were implanted into the back surface of the wafers and were then redistributed during a diffusion anneal for 30 min at 1100° or 900° C. Three Au-related trap levels have been observed in the interface region, which were attributed to the Au-donor (E v +0.35 eV), the Au-acceptor (E v +0.53 eV), and the Au-Fe complex (E v +0.45 eV). The trap concentration profiles show that the Si-SiO2 interface affects the Au concentration in a depth range of 1 μm from the interface and that gettering of Au occurs at the interface. The interface state density is independent of the Au concentration at the interface even for concentrations of 1015 cm−3.