Further optimization of a typically reported ferroelectric capacitor comprised of a Hf_0.5Zr_0.5O₂ ferroelectric thin film with TiN electrodes is explored by introducing an additional non-ferroelectric La₂O₃ interfacial layer evaluated at different positions in the capacitor stack. The role of the interface to the ferroelectric layer is investigated and discussed, with the main focus directed toward the reliability of the device for non-volatile memory applications. With this investigation, different degradation mechanisms determining electric field cycling and polarization retention are observed, and it is concluded that modifying the bottom interface between the electrode and the ferroelectric layer has the best potential to provide a benefit in device performance.