Theory to Predict Etching Shapes in Quartz Crystal and Its Application to Design Devices

Abstract

This paper describes the “micromachining” of quartz wafers by anisotropic etching of alpha-quartz. No previous systematic studies of the anisotropic etching of alpha-quartz have been reported, although such technology has been used to fabricate miniature quartz tuning fork resonators for wrist watches. Such micromachining technology differs from conventional planar integrated circuit processes in that its purpose is to produce three-dimensional devices.
The purpose of this investigation was to predict cross-sectional shapes of micromechanical devices made of quartz wafers using photolithography and anisotropic etching. The etching rates of quartz wafers with 21 different angles of cut were measured, and were interpolated using spline function in order to determine etching rate of all quartz crystal surface. As a result, the cross-sectional shapes of devices fabricated on wafers with any angle of cut could be predicted by applying Jaccodine's method.