Hafnium zirconium oxide (HZO) has been studied intensively due to its potential application to memory and logic devices based on its outstanding dielectric and ferroelectric properties. Because many process factors can significantly impact the properties of HZO thin film, an optimized process or post-treatment is necessary to ensure its performance. Herein, the effect of hydrogen on HZO thin film can make the film degraded. Analysis of the polarization-voltage hysteresis loops and I-V measurements indicate a leaky behavior in the film. To address this issue, post-oxygen-plasma treatment is performed on the film, which results in the decrease in hydrogen ions inside the film and consequently reduces the leakage current density. This finding can provide new insight into the effect of hydrogen incorporation for HZO thin films and methodology to remove leaky components inside ferroelectric films using O-2 plasma treatment.