The contradiction between thermodynamic and kinetic effects of stress-modulated antiferroelectricity in ZrO2 thin films†

Abstract

The discovery of antiferroelectricity in fluorite-structured binary oxides has opened up promising directions for next-generation electronic devices due to their excellent scalability and compatibility with silicon technology. However, understanding and improving the antiferroelectricity remain ambiguous and present considerable challenges for device applications. In this work, we discover a contradiction between the thermodynamic and kinetic effects of stress-modulated antiferroelectricity in ZrO₂ thin films. On the one hand, we observe a monotonically enhanced antiferroelectricity in a ZrO₂ thin film grown on the bottom electrode with a reduced coefficient of thermal expansion, i.e., ranging from Ni to TiN and W. The combined experimental characterizations and first-principle calculations show that the out-of-plane compressive stress induced by the electrode promotes the formation of the tetragonal phase, producing enhanced antiferroelectricity. On the other hand, the out-of-plane compressive stress increases the energy barrier between the tetragonal and polar orthorhombic phases, hindering the reversible phase transition between them. As a result, the antiferroelectricity of the samples annealed with top electrodes is worse compared to those without top electrodes. Our findings not only deepen the understanding of antiferroelectricity in ZrO₂ thin films but also provide a strategy for improvement.