Notching效应在MEMS单步干法制造工艺中的应用

研究了一种基于深反应离子刻蚀（DRIE）中notching效应的MEMS单步干法制造工艺.首先,基于DRIE刻蚀SOI硅片时notching现象产生的机理,设计了多种不同线宽的槽结构,验证notching效应的发生条件.实验结果表明,对于所采用的具有30μm器件层的SOI硅片,发生notching现象的临界槽宽为12μm,而notching释放的极限结构宽度同样为12μm.其次,为实现大面积结构的notching释放,研究了正方形、矩形、三角形及六边形等4种典型释放孔结构的干法释放效果.实验结果表明,六边形释放孔不但能够快速有效地释放结构,同时还能降低notch-ing效应的磨损,有利于惯性MEMS器件的加工.最后,设计了一种Z轴微机械陀螺结构以验证提出的设计及工艺.加工及测试结果表明,所提出的单步干法制造工艺完全满足微机械陀螺设计加工要求,工艺简单、成品率高,所测试的陀螺在常压下即可达到122的品质因数.

Application of Notching Effect in One-Step Dry Etch and Release Processfor 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.