Effects of La-Doped HfO2 Films on Dielectric Properties by Sol-Gel Method

Abstract

HfO2 and La-doped HfO2 with 20, 40, 50, and 60 mol% were deposited on silicon wafers by spin-coating technique. The crystallization process was annealed temperature at 600 °C. Then, characterization techniques of XRD, AFM, SEM, Full-field XRF imaging, and XAS were applied to reveal structural morphology, local structure, grain, distribution, etc. This study aims to investigate the effect of doping La into the HfO2 system on surface formation, microstructure, and dielectric properties. According to the results, RMS surface roughness, and grain size increased relative to La concentration levels. These films demonstrated homogeneous, low surface roughness, and crack-free. The XRD confirms the existence of the monoclinic phase in pure HfO2 and the mixture phase of the monoclinic and orthorhombic phases in La-doped HfO2 films. Increasing La concentration caused the structural transformation, the XAS of La L3 -edge indicating that lanthanum remained in the HfO2 system. Dielectric response based on interface-phase polarization was improved with La content from 0 mol% to 60 mol%. Compared with HfO2 film, the dielectric constant of La-doped HfO2 films was increased and dielectric loss was decreased.