摘要
The properties of tantalum oxide (Ta2 O5) metal-insulator-metal (MIM) capacitors with AlTaCuTa bottom electrodes were investigated. An ultrathin Al film successfully suppresses oxygen diffusion in the Ta2 O5 MIM capacitor with the Cu-based electrode. The electrical characteristics and reliability of Ta2 O5 MIM capacitors are improved by addition of ultrathin Al films. Ta2 O5 MIM capacitors have low leakage current density (1 nA cm2 at 1 MVcm) and high breakdown field (5.2 MVcm at 10-6 A cm2). The decrease in leakage current is attributed to the formation of a dense and uniform Al2 O3 layer, which has self-protection property and stops further oxygen diffusion into the tantalum contact. The dominant conduction mechanism of leakage current is the Poole-Frenkel effect at electric fields above 1.5 MVcm. © 2006 The Electrochemical Society. All rights reserved.