The Impact of Metal Contamination on the Quality of Thermal SiO2

To study the impact of a metal contanination on the quality of thermal oxides silicon wafers were intentionally contaminated by fast diffusing metals that tend to form silicides. Cu, Pd and Fe were found to be harmful, while Ni and Co did not cause any reductions of the breakdown field strengths of the oxides. Transimission electron microscopy studies showed that the reduction in gate oxide breakdown strength correlates with oxide thinning by metal silicide precipitates formed at the Si/SiO2 interface.