Abstract
Metal-insulator-metal (MIM) capacitors with excellent electrical properties have been fabricated using high-kappa TaAlOx-based dielectrics. TaAlOx films having thickness of 11.5-26.0 nm, with equivalent oxide thickness (EOT) of similar to 2.3-5.3 nm were deposited on top of Au/SiO2 (180 nm)/Si (100) structures by radio frequency magnetron co-sputtering of Ta2O5 and Al2O3 targets. The surface chemical states of the as-deposited TaAlOx films were characterized by high-resolution X-ray photoelectron spectroscopy. The crystallinity of the TaAlOx films for various post-deposition annealing treatments was characterized by grazing incident X-ray diffraction, which reveals that an amorphous phase is still retained for rapid thermal annealing up to 500 degrees C. Besides a high capacitance density (similar to 5.4 to 6.6 fF/mu m(2) at 1 kHz), a low value of voltage coefficients of capacitance and a stable temperature coefficient of capacitance have also been obtained in MIM capacitors with TaAlOx films. Degradation phenomenon of TaAlOx-based MIM capacitors under constant current stressing at 20 nA is found to be strongly dependent on dielectric thickness. It is shown that Al-incorporated Ta2O5 (TaAlOx) films with high band gap and good thermal stability, low leakage current and good voltage linearity make it one of the most promising candidates for metal-insulator-metal capacitor applications. (C) 2010 Elsevier B.V. All rights reserved.