Influence of Ta and TaN bottom electrodes on electrical performances of MIM capacitors with atomic-layer-deposited HfO2 dielectric

Based on atomic-layer-deposited high permittivity HfO2 films on both Ta and TaN substrates, we compare the influence of different bottom electrodes on electrical performance of metal-insulator-metal MIM capacitors. The experimental results indicate that the TaN bottom electrode can give higher capacitance density 7.47?fF/μm2 and smaller voltage coefficients of capacitance 356ppm/V2 and 493ppm/V, which are attributed to the high quality interface between TaN bottom electrode and HfO2 dielectric films. Moreover, a low leakage current of 5×10-8A/cm2 at 3V is achieved for both types of capacitors, and TaN bottom electrode-based MIM capacitors exhibit higher breakdown field. Finally, the conduction mechanism of the TaN-based capacitor is studied, showing a Schottky emission at room temperature.