Definition of high aspect ratio glass columns

Abstract

Abstract The paper is focused on the structuring of glass wafers to obtain high aspect ratio glass columns with high vertical profile for Micro Electro Mechanical Systems (MEMS). The technique proposed is to pattern columns by mechanical sawing. The sawing parameters have been optimised to achieve a high yield. Different dimensions of the column have been tested and glass columns down to 150 μm ×150 μm of cross-section and 700 μm height have been obtained. They present high aspect ratio (>100) and very good vertical profile (88–90°). Hoya SD-2 and Corning Pyrex #7740 glass wafers have been processed with similar results. Different cleaning procedures have been tested to improve the anodic bondability of the samples after sawing. Machined glass columns have also been structured by commercial sand blasting technique and the results are also compared to the sawed samples. The glass wafers with machined columns have been anodically bonded to silicon. Anodic bonding characterisation of glass columns of different sections is also presented. Pull tests confirmed the good bondability of the glass columns.