An optimized one-step wet etching process of Pb(Zr0.52Ti0.48)O₃thin films for microelectromechanical system applications

The existence of insoluble residues as intermediate products produced during the wet etching process is the main quality-reducing and structure-patterning issue for lead zirconate titanate (PZT) thin films. A one-step wet etching process using the solutions of buffered HF (BHF) and HNO 3 acid was developed for patterning PZT thin films for microelectomechanical system (MEMS) applications. PZT thin films with 1 µm thickness were prepared on the Pt/Ti/SiO 2 /Si substrate by the sol–gel process for compatibility with Si micromachining. Various compositions of the etchant were investigated and the patterns were examined to optimize the etching process. The optimal result is demonstrated by a high etch rate (3.3 µm min −1 ) and low undercutting (1.1: 1). The patterned PZT thin film exhibits a remnant polarization of 24 µC cm −2 , a coercive field of 53 kV cm −1 , a leakage current density of 4.7 × 10 −8 A cm −2 at 320 kV cm −1 and a dielectric constant of 1100 at 1 KHz.