Hafnium zirconium silicon oxide ((HfZrO₄)1-x(SiO₂)x) materials were investigated through the defect analysis and reliability characterization for next generation high-κ dielectric. Silicate doped hafnium zirconium oxide (HfZrO4) films showed a reduction of negative flat-band voltage (Vfb) shift compared to pure HfZrO₄. This result was caused by a decrease in donor-like interface traps (Dit) and positive border traps (Nbt). As the silicon oxide (SiO₂) content increased, the Vfb was shifted in the positive direction from -1.23 to -1.10 to -0.91 V and the slope of the capacitance-voltage (C-V) curve increased. The nonparallel shift of the C-V characteristics was affected by the Dit, while the Nbt was responsible for the parallel C-V curve shift. The values of Dit reduced from 4.3 × 1011, 3.5 × 1011, and 3.0 × 1011 cm-2eV-1, as well as the values of Nbt were decreased from 5.24, 3.90 to 2.26 × 1012 cm-2. Finally, reduction of defects in the HfZrO₄-base film with an addition of SiO₂ affected the gate oxide reliability characteristics, such as gate leakage current (JG), bias temperature stress instability (BTSI), and time dependent gate dielectric breakdown (TDDB).