Structure evolution and charge hysteresis in buried Hafnia-Alumina oxides

• Studying the high-k buried oxide (BOX) ferroelectric phase evolution was made by GIXRD after RTA up to the temperature as high as 950 °C. • The Fm 3 m cubic phase dominates after the step-by-step RTA treatment opposite to the isochronal RTA treatment for hafnia based BOX. • There is a FE-like hysteresis due to interface dipole polarization or defect charge trapping from RT up to 300 °C. • The Fe-like hysteresis gives a more remarkable contribution after the step-by-step RTA treatment than that after the isochronal RTA treatment. Analysis of the high-k buried oxide phase evolution by the X-ray study, pseudo-MOSFET and CV measurements was used to separate the ferroelectric and interface dipole polarization, and charge trapping up to 300 °C. The thermal budgets during the rapid thermal annealing (RTA) 30 s at temperatures 600 to 1000 °C were established for different hafnia based stacks to ensure the recrystallization of HfO 2 layers and preservation of ferroelectric hysteresis. The highest hysteresis was obtained at the RTA stepwise temperature increase to 900 °C for the stack with supercicles HfO 2 :Al 2 O 3 (10:1).