Performance comparison of methods to evading notching effect for SOG structures in DRIE

This paper experimentally compared the performance of two existing anti-notching methods for silicon on glass structures in deep reactive ion etching process. The two methods employed a same concept, by sputtering an electrically conducting metal layer to evacuate the charges of etching radicals to silicon substrate and eliminate the buildup of electric field. The difference between them is where the layer is sputtered, one on the glass top surface whereas the other one right on the bottom surface of silicon structures. The effectiveness of the two methods was characterized and studied through optical measurement and electrical test by applying them into inertial sensors, demonstrating a result that the latter method is much better than the former, and the reasons of which are discussed.