The Electrical and Reliability Characteristics of Dysprosium Oxide and Holmium Oxide Gate Dielectrics

• Main Authors: Wen Tsung Chang, 張文聰
• Other Authors: T. M. Pan
• Format: Others
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/99786063321036846002

碩士 === 長庚大學 === 電子工程學研究所 === 97 === In this thesis, we selected two high-k materials as the gate dielectric of metal-oxide-semiconductor capacitors. One is dysprosium oxide (Dy2O3) and the other is holmium oxide (Ho2O3). Through PDA treatment, we analyzed its physical properties. We use X-ray diffraction (XRD), X-ray photoelectron Spectroscopy (XPS), and Atomic Force Microscopy (AFM) to identify the oxide film crystallization, chemical composition, and surface morphology. After using Al as gate electrode, we investigated its electrical and reliability characteristics. The analyses of electrical properties have C-V curves, hysteresis phenomenon, interface state density, and leakage current. We found dysprosium oxide and holmium oxide have a larger capacitance value when the annealing temperature is 600℃ and exhibited a lower hysteresis voltage. And, we also explored the reliability of dysprosium oxide and holmium oxide. In dysprosium oxide, we discuss charge-to-breakdown (QBD) and time-dependent-dielectric-breakdown (TDDB) in gate oxide reliability. The Weibull slope is almost independent of current stress, gate area, and temperature for Dy2O3 in QBD. The Weibull slope is almost independent of stress voltage for Dy2O3 in TDDB. In holmium oxide, we discuss charge-to-breakdown (QBD) in gate oxide reliability. The Weibull slope is almost independent of current stress, gate area, and temperature for Ho2O3 in QBD. We found the oxide breakdown for these two high-k material belonged to intrinsic breakdown. It means the oxide breakdown is caused by stress-induced charge traps. Finally, we used the cell-base analytic model to extract the defect size of Dy2O3 thin film. The defect size of Dy2O3 is 4.5 nm for α=0.6 and 7.5 nm for α=1.