Effects of capping and seed layers on ferroelectricity of Ti-doped HfO2 with low-temperature annealing

Abstract

The fabrication of HfO₂-based ferroelectric films typically relies on high-temperature rapid annealing to induce ferroelectricity. The excellent ferroelectric properties of HfO₂-based films obtained by low-temperature treatment have always attracted widespread attention. Here, we deposited Ti-doped HfO₂ thin films with different concentrations on n-type highly doped Si wafers by magnetron sputtering and reported the electrical properties of Ti-doped HfO₂ films after treatment at different temperatures. Hysteresis loop measurements and piezoresponse force microscopy (PFM) confirmed that films subjected to low-temperature treatment (400 °C) exhibited strong ferroelectric behavior. X-ray photoelectron spectroscopy (XPS) analysis revealed that Ti doping effectively optimized the distribution of oxygen vacancies in the HfO₂ films. Additionally, undoped HfO₂ or Al₂O₃ was employed as a capping layer for a 20 nm thick Ti-doped HfO₂ film (Hf_0.9Ti_0.1O₂). After rapid annealing in an N₂ environment at 400 °C, a significant enhancement in the film's ferroelectric properties was observed. The development of HfO₂-based films with excellent ferroelectric performance through low-temperature processing is of great importance for enhancing the compatibility of HfO₂ films with CMOS fabrication processes.