Structural and electrical characterization of Lu ₂O ₃ dielectric layer for high performance analog metal-insulator-metal capacitors

The structural and electrical properties of Lu ₂O ₃ dielectric films deposited by radio frequency (RF) magnetron sputtering on TaN electrode have been studied for metal-insulator-metal (MIM) capacitor in analogRF 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 Lu ₂O ₃ film decreases after annealing at 400°C using atomic force microscopy. The chemical composition of the Lu ₂O ₃ film was characterized by X-ray photoelectron spectroscopy. The MIM capacitor using a Lu ₂O ₃ dielectric film exhibited better electrical characteristics, such as a low leakage current of 5 × 10 ^-8 Acm ² at -1 V and a high capacitance density of 7.5 fF/μm ² with a low quadratic voltage coefficient of capacitance of 75 ppm/V ². 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.