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TiO2/SiO2 stacked dielectric-based metal-insulator-metal capacitors with different thermal and nitrogen plasma treatments (NPTs) were explored in this letter. As the TiO2 dielectric crystallizes from amorphous phase after a thermal treatment, capacitance density increasing from 7.7 to 11.9 fF/m2 was obtained at the price of aggravating leakage current and wider distribution in device characteristics. With NPT to well passivate grain-boundary-related defects in the crystalline TiO2 film, devices still keep a satisfactory capacitance level of 11.2 fF/μm2 while exhibiting suppressed leakage current by a factor of 53, a lower quadratic voltage coefficient of capacitance (VCC-α) of 30 ppm/V2, near frequency dispersion-free capacitance, a better temperature coefficient of capacitance of 82 ppm/°C, and more controllable device uniformity. The mechanism for the improved electrical characteristics was further confirmed by atomic force microscope. These results suggest that NPT paves a new avenue to further advance the performance of crystalline dielectric-based devices.