Etching of quartz crystals in liquid phase environment: A review

Quartz crystals are the most widely used material in resonant sensors, owing to their excellent piezoelectric and mechanical properties. With the development of portable and wearable devices, higher processing efficiency and geometrical precision are required. Wet etching has been proven to be the most efficient etching method for large-scale production of quartz devices, and many wet etching approaches have been developed over the years. However, until now, there has been no systematic review of quartz crystal etching in liquid phase environments. Therefore, this article provides a comprehensive review of the development of wet etching processes and the achievements of the latest research in this field, covering conventional wet etching, additive etching, laser-induced backside wet etching, electrochemical etching, and electrochemical discharge machining. For each technique, a brief overview of its characteristics is provided, associated problems are described, and possible solutions are discussed. This review should provide an essential reference and guidance for the future development of processing strategies for the manufacture of quartz crystal devices.