Application of notching effect in one-step dry etch and release process for the fabrication of MEMS

This paper presented a one-step dry release process using the deep reactive ion etching (DRIE) notching effect for the fabrication of micro-electromechanical systems (MEMS) device. At first, based on the formation mechanism of the notching in DRIE, the experiment was designed to verify the notching using kinds of trenches with different widths. Results show that, for the 30 μm SOI wafers, the trench width should be below 12 μm to initiate notching, and the released components of the device should be less than or equal to 12 μm wide to ensure the notching release. Secondly, four kinds of release holes, such as square, rectangle, triangle and hexagon, were designed and fabricated through one-step dry release process. Results show that the hexagon holes can not only shorten the overetching time but also reduce the damage of the notching, for the fabrication of MEMS device. Finally, a Z-axis MEMS gyroscope was designed and fabricated for verification. The one-step dry release process we presented is suitable for the fabrication of the MEMS gyroscope with a simple process, high yield, and a high quality factor of 122 at atmosphere for the fabricated MEMS gyroscope.