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We demonstrate electrical properties of rare earth (RE)-doped HfO2 and ZrO2 for application as higher permittivity (k) dielectrics in logic and memory devices. X-ray diffraction (XRD) results show that Dy, Er, and Gd doping stabilizes the higher-k tetragonal phase rather than the lower-k monoclinic phase. This preferred tetragonal phase results in a k~30. Initial electrical results show ~3 nm higher-k enables an equivalent oxide thickness (EOT) of 0.93 nm. Alternatively, ~7nm higher-k reduces leakage currents 1000x relative to HfO2 achieving <10-8 A/cm2 at an EOT of 2 nm. Capacitance-voltage (C-V) data show increasing amounts of RE dopants shift flatband voltage (Vft) in the negative direction vs. pure HfO2.
Date of Conference: 23-25 April 2007