Interface control of Y ₂O ₃ thin film with Si(100) in a metal-(ferroelectric)-insulator-semiconductor structure

Y-metal deposition on chemical oxide of Si and vacuum annealing was adopted to control the interface for the formation of Y ₂O ₃. Free interfacial SiO ₂ state and Y-silicate with small amount of Y ₂O ₃ on top was obtained through vacuum annealing of Y-metal on the chemical oxide system. Furthermore, an effective suppression of interfacial SiO ₂ formation was also observed during the formation of Y ₂O ₃ on the interface-controlled system and an improvement of electrical properties was achieved. When compared with Y ₂O ₃ on a HF-cleaned Si system, a small positive shift of flatband voltage in capacitance-voltage characteristic was observed with Y ₂O ₃ on the interface-controlled system with Y-silicate. A smaller leakage-current behavior of 1-2 orders was obtained with the controlled system than with Y ₂O ₃ on a HF-cleaned Si system, with 2.5 V higher breakdown voltage.