We have studied the Cu contamination effect on 4.2 nm thick Al2O3 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 K value and lower gate dielectric leakage current. (C) 2004 The Electrochemical Society.