Enhancement effect of germanium on oxygen precipitation in Czochralski silicon

Oxygen precipitation in germanium (Ge)-doped Czochralski (CZ) silicon has been investigated through a series of isothermal anneals at temperatures ranging from 550to950°C. It is found that the nucleation of oxygen precipitates can be enhanced in a wide temperature range and the onset temperature for precipitate nucleation can be increased by the germanium doping. Furthermore, it is also revealed that the oxygen precipitates with a higher density and smaller sizes can be formed in germanium-doped CZ silicon in comparison with those in conventional CZ silicon. These two phenomena are ascribed to the reduction in the critical radius for oxygen precipitation and the increase in the concentration of heterogeneous nuclei due to the germanium doping.