An optimized one-step wet etching process of Pb(Zr0.52Ti0.48)O3 thin 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 HNO3 acid was developed for patterning PZT thin films for microelectomechanical system (MEMS) applications. PZT thin films with 1 mu m thickness were prepared on the Pt/Ti/SiO2/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 mu m min(-1)) and low undercutting (1.1: 1). The patterned PZT thin film exhibits a remnant polarization of 24 mu C cm(-2), a coercive field of 53 kV cm(-1), a leakage current density of 4.7 x 10-8 A cm(-2) at 320 kV cm(-1) and a dielectric constant of 1100 at 1 KHz.