Experimental investigations on ferroelectric dielectric breakdown in sub-10 nm Hf0.5Zr0.5O2 film through comprehensive TDDB characterizations

A deep insight is aimed at into the degradation of ferroelectric thin film and, systematical time-dependent dielectric breakdown characterizations in sub-10 nm Hf0.5Zr0.5O2 (HZO) film are performed and analyzed in this work. First, it is found that the anti-ferroelectric t-phase becomes more competitive when the film thickness decreases, and the wake-up effect is related to the phase transition. Second, the experimental phenomenon proves the correlation between soft breakdown and hard breakdown in the thin film, especially at low voltages. Furthermore, it is evident that a larger hard breakdown Weibull slope presents in thinner HZO film, showing the opposite trend to conventional dielectrics such as SiO2. The underlying mechanisms are discussed, and it is concluded that the t-phase interface layer, as well as the pre-existing defects in bulk film, are important factors for thin HZO-based devices.