Modulation of crystal structure and electrical properties of Hf0.6Zr0.4O2 thin films by Al-doping

Abstract The electrical properties of Hf- and Zr-based oxide thin films, which are related to their crystal structure, are sensitively dependent on their composition and process conditions. In particular, HfZrO 2 mixed thin films, which have potential applicability as high-k dielectrics, can have various polarization phases, including paraelectric, ferroelectric, and anti-ferroelectric phases. Therefore, we investigated the enhancement of the dielectric properties of HfZrO 2 thin films upon Al doping by confirming their polarization characteristics. Doping of the HfZrO 2 thin film with a small amount of Al (∼2.5%) caused a remarkable increase in the dielectric constant to ∼47 and modified the polarization phase from ferroelectric to paraelectric, and the doped film subsequently showed an excellent leakage current of about 2 × 10 −8  A/cm 2 at ± 1 MV/cm. On the basis of these findings, we believe that Al-doped HfZrO 2 films are promising candidates for use as paraelectric high-k dielectrics for dynamic random access memory capacitors, as gate dielectrics for high-speed transistors, and so on.