The Etching Structure Research For Quartz At-cut And BT-cut Based On The Maximum Positive Curvature Method

Quartz is currently an important research direction of MEMS,but the diversity of crystallographic planes and the complex anisotropy make it difficult to predict the results of wet etching.Based on the wet etching experiments of quartz hemispheres and different crystal substrates,the paper presents a simpler and more efficient calculation method of quartz etching morphology based on the Wulff-Jaccodine method.By using this method,the structural planes of different crystal facets of quartz are explored in depth,and the internal laws of the anisotropy of different crystal planes are obtained,which can efficiently reduce the development cycle of specific microstructures and save experimental costs.The research work is mainly as the followings:Firstly,the crystal structure of quartz and etching mechanism are analyzed.The etching data base of any crystallographic orientations of alpha-quartz is created by wet etching of quartz hemispheres in five different etching environments and variation of the rates of quartz in different etching environments is analyzed.This provides data support for multiple simulation methods of quartz wet etching.Secondly,the structures of rectangular grooves in all directions can be obtained by etching AT-cut and BT-cut in saturated ammonium at 80 degrees.The maximum positive curvature recognition method is proposed based on the experimental data and the etching rate of quartz hemisphere.By using this method,the etching structures of any crystallographic planes of quartz can be quickly calibrated,and the regularity of the distribution of the crystallographic planes in wet etching can be explained.Thirdly,wet etching experiments of complex structures are performed,including mesas,cavities and micro-needles.The reason for the formation of etched structural planes are analyzed using rectangular groove data derived from the maximum positive curvature recognition method is verified.Finally,the maximum positive curvature recognition method is used to explore the high aspect ratio of quartz in different etching environments,and the microscopic mechanism of the etching rate anisotropy of quartz is analyzed from the perspective of atom arrangement.