HfO2-based thin films and devices

Abstract

HfO₂-based thin films and devices have attracted considerable interest owing to their outstanding properties, such as high dielectric constant, robust ferroelectricity, wide bandgap, excellent thermal stability, and full compatibility with complementary metal-oxide-semiconductor (CMOS) processing. As a high-k gate dielectric, HfO₂-based films have already replaced SiO₂ in certain advanced CMOS technologies, facilitating the development of faster, smaller, and more energy-efficient integrated circuits. In particular, the discovery of ferroelectricity in doped HfO₂ thin films in 2011 further established HfO₂-based ferroelectrics as promising candidates for next-generation memory technologies [1], [2]. Their advantages are evident: 3D conformable HfO₂ films can be deposited by atomic layer deposition (ALD) and crystallized at CMOS-compatible low temperatures, and robust ferroelectricity is maintained at thicknesses <10 nm. These characteristics make them highly suitable for nonvolatile memory, negative-capacitance transistors, etc., offering the prospects of higher speed and lower power consumption for CMOS devices. Hence, industrial progress is also evident: for instance, in 2023, Micron Technology introduced a 32 Gb high-density ferroelectric random-access memory (FeRAM) device based on ferroelectric HfO₂, exceeding the ∼16 Mb capacity of commercial perovskite-based FeRAMs and highlighting its scalability [3].