Impact of reduced pressure crystallization on ferroelectric properties in hafnium-zirconium dioxide films deposited by sputtering

Abstract

Abstract The impact of reduced pressure annealing on ferroelectric properties in hafnium-zirconium oxide (HZO) films deposited by sputtering has been investigated. It is demonstrated that the HZO films annealed at 600 °C at less than 100 Pa show excellent ferroelectric properties, whereas the HZO films annealed at more than 1000 Pa show degraded electrical properties. This is presumably due to the introduction of oxygen vacancies, which stabilize the ferroelectric orthorhombic phase. Thermal stability can be also improved for the HZO films annealed at reduced pressures. In addition, ferroelectric gate transistor operation is demonstrated using an HZO gate insulator annealed at 100 Pa with the indium-tin-oxide channel.