Hysteresis reduction by fluorine incorporation into high permittivity tetragonal ZrO2 on Ge.

Utilizing remote NH₃/H₂ plasma on GeO₂/Ge can achieve the nearly-free interfacial layer and low equivalent oxide thickness of ~0.4 nm by the formation of tetragonal ZrO₂ phase. However, the electrical defects in ZrO₂ result in a large C-V hysteresis (~580 mV). The fluorine incorporation by CF₄ plasma is demonstrated to effectively passivate these defects both experimentally and theoretically. The hysteresis is reduced to be ~200 mV, and the interface defect density, permittivity, and gate leakage current remain intact. The Zr-F bond formation to remove the midgap states calculated by the density-function-theory may be the origin of passivation. [ABSTRACT FROM AUTHOR]