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, HfZrO2 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 HfZrO2 thin films upon Al doping by confirming their polarization characteristics. Doping of the HfZrO2 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/cm2 at ± 1 MV/cm. On the basis of these findings, we believe that Al-doped HfZrO2 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.