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Sungsoo Park(박성수),Byoungdeog Choi(최병덕) 대한전자공학회 2023 대한전자공학회 학술대회 Vol.2023 No.6
High-k dielectric materials are popularly being used in devices such as gate insulators or cell capacitors. Dielectrics using high-k materials guarantee high permittivity, yet tend to get more leakage current and eventually be made up for laminated structures. This study investigates the differences in electrical characteristics of metal-insulator-metal (MIM) capacitors composed of ZrO₂-Al₂O₃-ZrO₂ (ZAZ) laminate dielectric under three varying bottom electrode-alumina distances (Db). Each ZAZ was laminated on a highly doped polycrystalline silicon substrate with extremely low resistivity, using atomic layer deposition (ALD). Lastly, aluminum electrodes with 300 μm diameter and 70 nm thickness are deposited by an electron-beam evaporator (E-beam) on the top of the laminates. For each of the three ZAZs, characteristics of capacitance, normalized capacitance, and leakage current density were measured. The capacitance shows a slight increment as Db enlarges. However, the changes in normalized capacitances are the smallest when the interlayer alumina is located in the center. From this investigation, it is identifiable that the leakage current density and capacitance increase as the alumina layer is stacked closer to the aluminum electrode. Nevertheless, more variance in the capacitance happened as the alumina layer gets closer to either side of the electrodes. These phenomena result from the trapped electron charges of the quantum well developed in the oxide interface. The interface electrons of the zirconia-alumina interface are induced through zirconia, by Thermionic-emission and Poole-Frenckel emission. This experiment is expected to be helpful to define an ideal laminate method for MIM capacitor dielectrics.