Improved ferroelectric and endurance properties of Hf0.5Zr0.5O2 thin films by a replacement indium-tin-oxide top electrode process

Abstract

The ferroelectricity in HfO2-based thin films offers a potential alternative to non-volatile memories and logic devices. Special top electrodes such as nitride metal serving as a mechanical capping layer are used to induce the ferroelectricity in HfO2, which hinders the extensive application of HfO2 ferroelectrics. Indium-tin-oxide (ITO) is a transparent, highly conductive electrode or semiconductor, widely used in microelectronics. Here, we comprehensively investigated the impact of ITO electrodes on the ferroelectric polarization and endurance properties of Hf0.5Zr0.5O2 (HZO) thin films. The remnant polarization (2P r) of ∼23.6 μC cm−2 was obtained for the ITO#/HZO/TiN capacitors with an electrode-replacement technique. The relatively enlarged coercive field of ±1.25 MV cm−1 was observed in the ITO/HZO/TiN capacitors compared with TiN/HZO/TiN structures (±0.94 MV cm−1). This might be owing to the work function difference between top ITO and bottom TiN electrodes, as well as the depletion effect of the ITO interface. Furthermore, stable endurance characteristics after 108 cycles were obtained in the ITO#/HZO/TiN capacitors. This work provides a new strategy to obtain excellent ferroelectricity and good reliability in HfO2-based ferroelectric thin film integration with other oxide electrodes.