Wang Haoran, Godara Manish, Chen Zhenfang, Xie Huikai
Department of Electrical and Computer Engineering, University of Florida, Gainesville, USA.
Department of Chemical Engineering, University of Florida, Gainesville, USA.
Sens Actuators A Phys. 2019 May 1;290:130-136. doi: 10.1016/j.sna.2019.03.028. Epub 2019 Mar 19.
Lead zirconate titanate (PZT) has wide applications in microelectromechanical systems (MEMS) due to its large piezoelectric coefficients. However, there exist serious issues during PZT wet etching even with multiple etching steps, such as residues on etching fronts and large undercut. In this paper, a one-step residue-free wet etching process of ceramic PZT is developed with fluoroboric acid. In this work, the design of experiments (DOE) method is employed to minimize undercut and residues without sacrificing etching rate. The acid concentration, temperature, and agitation are the process parameters considered in the DOE. Through DOE analysis of the experimental data, an optimal recipe is identified as the volume ratio of HBF:HO=1:10 at 23 °C. This new PZT etching recipe leads to a high etching rate (1.54 μm/min) with no observable residues and a small undercut (0.78:1) as well as a high selectivity over the photoresist (900:1). This etching recipe can be used for making various piezoelectric transducers.
锆钛酸铅（PZT）因其较大的压电系数而在微机电系统（MEMS）中具有广泛应用。然而，即使采用多步蚀刻，PZT湿法蚀刻过程中仍存在严重问题，例如蚀刻前沿的残留物和较大的底切。本文利用氟硼酸开发了一种陶瓷PZT的一步无残留湿法蚀刻工艺。在这项工作中，采用实验设计（DOE）方法在不牺牲蚀刻速率的情况下尽量减少底切和残留物。酸浓度、温度和搅拌是DOE中考虑的工艺参数。通过对实验数据的DOE分析，确定了最佳配方为在23°C时HBF:HO的体积比为1:10。这种新的PZT蚀刻配方具有高蚀刻速率（1.54μm/min），无明显残留物，底切小（0.78:1），并且对光刻胶具有高选择性（900:1）。该蚀刻配方可用于制造各种压电换能器。
