Effects of isopropyl alcohol and acetic acid on surface roughness of Z‐cut quartz etched by ammonium bifluoride solution

Abstract

Quartz has been widely used in modern microelectromechanical systems (MEMS) industry, and wet etching is one of the primary techniques used for its manufacturation. There are many reported literatures focused on the study of etched profiles or etching rate of quartz, but few on its surface quality. Inspired by the surface quality improved by using additives in the silicon wet etching process, the effects of isopropyl alcohol (IPA) and acetic acid on the surface roughness of Z-cut quartz etched by ammonium bifluoride (NH 4 HF 2 ) solution were investigated for the first time. Different concentration of IPA or/and acetic acid was added into the NH 4 HF 2 solution, and the morphology of the etched surface was observed using scanning electron microscope and measured by a surface profilometer. It was found that the surface roughness of the Z-cut quartz decreased with the increasing of IPA or acetic acid concentration. Moreover, the etched surface roughness could be further decreased by using the ternary solution containing IPA and acetic acid. The best etched result ( R a = 0.12 μm) was obtained when the solution is composed of saturated NH 4 HF 2 + 15% v/v IPA + 10% v/v acetic acid. This work provides a new method to improve the surface quality of Z-cut quartz, and it will benefit the future design and manufacturation work of quartz MEMS devices.