High-quality patterning technique for polarization-enhanced (Ba0.67Sr0.33TiO3/LaNiO3)n multi-interface multilayer hetero-structure

Abstract

In this paper, a fabrication method for a patterned (Ba0.67Sr0.33TiO3, BST/LaNiO3, LNO)n thin-film multilayer is reported. The multilayer films were deposited by radio-frequency (RF) magnetron sputtering. A patterning technique of the as-prepared multilayer thin films was developed using ultrasonic-assisted wet etching. The scanning electron microscopy (SEM) surface images show that the developed technique can effectively etch the multilayer thin films deposited on SiO2 and Pt substrates without any residues. The etched multilayer thin film units of the size of 50 μm × 50 μm display clear and smooth etching edges, low distortions (<1 μm) and high uniformity. The dielectric properties of these units for the (BST/LNO)2 multilayer thin films include a high dielectric constant (>900) and a relatively low loss tangent (<0.035) at frequencies below 10 kHz. The capacitance density ranges from 9 nF/mm2 for (BST/LNO)1–24.5 nF/mm2 for (BST/LNO)5 multilayer thin films at 1 kHz, and all these multilayer thin film units withstand a DC voltage of 24 V. This study can facilitate the development of the application of multi-interface multilayer ferroelectric micro-devices.