A Novel Wet Etching Process of Pb(Zr,Ti)O_3 Thin Films for Applications in Microelectromechanical System

摘要

The wet etching of Pb(Zr,Ti)O_3 (PZT) thin films has gained considerable attention in microelectromechanical systems (MEMS) since it is economical and effective compared with dry-etching methods. In this paper, a novel wet-etching process is proposed for PZT thin film patterning using 1BHF:2HCl:4NH_4Cl:4H_2O solution as the etchant, where NH_4Cl is used as an additive to decrease the undercutting of the obtained PZT pattern. According to energy dispersion spectroscopy (EDS) analysis and X-ray diffraction (XRD) patterns, PbClF particles were left as residues on the substrate after etching using 1BHF:2HCl:4NH_4Cl:4H_2O solution. Therefore, an additional 2HNO_3:1H_2O etching process was applied to convert PbCIF to PbCl_2, which can be dissolved completely in deionized water. This process exhibits a high etching rate (0.016 μm/s) and good selectivity over the photoresist and Pt bottom electrode. Using this technique, PZT patterns with acceptable undercutting (1.5:1) can be obtained.