Structural and Electrical Characterization of Lu2O3 Dielectric Layer for High Performance Analog Metal-Insulator-Metal Capacitors.

The structural and electrical properties of Lu₂O₃ dielectric films deposited by radio frequency (RF) magnetron sputtering on TaN electrode have been studied for metal-insulator-metal (MIM) capacitor in analog/RF applications. From X-ray diffraction study, it is observed that the deposited films remain amorphous within the thermal budget (400°C) of back-end-of-line process. The root mean square value of surface roughness of the Lu₂O₃ film decreases after annealing at 400°C using atomic force microscopy. The chemical composition of the Lu₂O₃ film was characterized by X-ray photoelectron spectroscopy. The MIM capacitor using a Lu₂O₃ dielectric film exhibited better electrical characteristics, such as a low leakage current of 5 × 10^-8 A/cm² at −1 V and a high capacitance density of 7.5 fF/µm₂ with a low quadratic voltage coefficient of capacitance of 75 ppm/V². The current conduction mechanism was found to be dominated by Schottky emission mechanism in low electric field (<1 MV/cm) region and hence further improvement in the leakage characteristics can be realized by employing a high work-function electrode or a large bandgap oxide as a barrier layer. [ABSTRACT FROM AUTHOR]