Review on the Microstructure of Ferroelectric Hafnium Oxides

Ferroelectric hafnium oxide is of major interest for a multitude of applications in microelectronics, ranging from neuromorphic devices to actuators and sensors. While the electrical performance is commonly discussed in depth, the influence of the microstructure is often disregarded. However, in recent years, more research groups shed light into the microstructural background of ferroelectric behavior in hafnium oxide films. To give a more general and complete picture of the different influences on the microstructure and its relevance for the applications, the process and stack influences on the microstructure are reviewed and summarized. While a few mechanisms are not yet understood in depth, a coherent picture on the formation of the microstructure in ferroelectric hafnium oxide layers can be gained.