TiN/Gd:HfO_2/TiN capacitors grown by PEALD showing high endurance ferroelectric switching

摘要

TiN/Gd:HfO_2/TiN metal/ferroelectric/metal structures were elaborated in one batch by plasma enhanced atomic layer deposition. The crystal structure and ferroelectric properties of 12-nm-thick Gd-doped HfO_2 thin films are investigated. The modulation of the Gd content within the HfO_2 layer leads to a subsequent variation of crystalline phases; predominance of the orthorhombic phase correlates with a maximum 2·P_r value of 30 μC/cm~2 for 1.8% of Gd doping as well as a ferroelectric polarization switching endurance up to 7 × 10~9 cycles. These remarkable properties of Gd:HfO_2 material compared to previous works are likely the consequence of nonexposure to air of metal/insulator interfaces during stack deposition, preventing their oxidation and/or carbon contamination.