This study investigates the degradation and improvement of the dielectric properties of ZrO2-based metal-insulator-metal (MIM) capacitors using TiSiN electrodes. As dynamic random-access memory (DRAM) design rules scale down, the mechanical properties of TiSiN electrodes provide advantages over conventional TiN, but also introduce challenges due to Si diffusion into ZrO2 films, forming low-dielectric constant (k) Zr-silicate and defect-related dielectric degradation. We evaluate the dielectric properties of ZrO2 films on TiSiN electrodes and identify significant reductions in the dielectric constant and an increase in DC and AC non-linearity due to Zr-silicate formation. To mitigate these problems, a Y2O3 passivation layer is introduced between the TiSiN electrode and ZrO2 dielectric film. Physical and chemical analyses, including X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), confirm that Y2O3 passivation effectively suppresses Si diffusion, preventing formation of Zr silicate, and preserving the high-k tetragonal phase of ZrO2. Electrical measurements show that the Y2O3 layer significantly improves the dielectric constant and reduces non-linearity effects. Notably, even at a reduced ZrO2 thickness of 4 nm, a relatively high k value is maintained with Y2O3 passivation. This study concludes that the Y2O3 passivation layer is indispensable for maintaining high dielectric performance in ZrO2-based MIM capacitors with TiSiN electrodes, ensuring stability and efficiency in advanced DRAM applications.