The copper contamination effect of Al₂O₃ gate dielectric on Si

We have studied the Cu contamination effect on 4.2 nm thick Al ₂O₃ metal-oxide semiconductor (MOS) capacitors with an equivalent-oxide thickness (EOT) of 1.9 nm. In contrast to the large degradation of gate oxide integrity of control 3.0 nm SiO₂ MOS capacitors contaminated by Cu, the 1.9 nm EOT Al₂O₃ MOS devices have good Cu contamination resistance with only small degradation of gate dielectric leakage current, charge-to-breakdown, and stress-induced leakage current. This strong Cu contamination resistance is similar to oxynitride (with high nitrogen content), but the Al₂O₃ gate dielectric has the advantage of higher κ value and lower gate dielectric leakage current.