Capacitance Boosting of Antiferroelectric-Hf_0.2Zr_0.8O₂/Al₂O₃ Blocking Layer Using Y₂O₃ Interfacial Layer for Charge Trap Flash Memory

A Y₂O₃ interfacial layer is introduced to enhance the capacitance of the blocking layer stacked with antiferroelectric (AFE)-Hf_0.2Zr_0.8O₂ (HZO) and Al₂O₃ films in charge trap flash (CTF) memories. The ultrathin Y₂O₃ film, with a target thickness of 2 nm, intermixes with the HZO film during the atomic layer deposition (250 °C) of HZO and promotes stabilization of the AFE tetragonal phase during postmetallization annealing (600 °C). Significant increases in the spontaneous polarization and maximum dielectric constant are achieved in the AFE-HZO/Y₂O₃ structure compared with the single-layer AFE-HZO structure. When Si₃N₄-based CTF devices are fabricated with an AFE-HZO/Al₂O₃ blocking layer utilizing the capacitance-boosting effect, the introduction of a Y₂O₃ interfacial layer results in performance enhancement in terms of memory window and programming efficiency. These improvements are attributed to the enhanced negative capacitance effect, which stems from the increased spontaneous polarization in the AFE-HZO film due to Y₂O₃ doping.