Effect of metal contacts on the electrical characteristics of Al2O3 dielectric thin films

The effect of top metal electrodes on the electrical characteristics of Al2O3 metal-insulator-metal capacitors is studied. The leakage current and breakdown characteristics were observed to have a strong dependence on the electrode material. Devices with Al electrodes exhibited significantly higher breakdown voltages compared to devices with Au, Ni, Cu, and Ag electrodes. Introducing an Al diffusion barrier dramatically increased the breakdown field and reduced the leakage current for capacitors with Ag, Au, and Cu electrodes. The electrical characteristics were found to relate well to material properties of the contacting metals, such as ionization potential and diffusion coefficient. (C) 2008 American Institute of Physics.