低g值微惯性开关防粘连结构的设计与制作

Design and Fabrication of the Anti-Stiction Structure for Low-g Micro Inertial Switches

低g值微惯性开关是一种感受惯性加速度、执行开关机械动作的精密惯性装置。为了解决开关芯片在清洗干燥过程中的粘连问题,提高器件的成品率,提出了防粘连的梯形凸台结构。该结构尺寸约为135μm×135μm×20μm,采用玻璃无掩膜湿法腐蚀技术在深约85μm的玻璃封盖底部实现。通过减小质量块与玻璃封盖底部的接触面积,弱化液体表面张力和范德华力的影响,避免了粘连现象的发生,使得低g值微惯性开关芯片在清洗干燥环节的合格率约达95%。采用MEMS体硅加工工艺和圆片级封装技术,完成了带有防粘连凸台结构的低g值微惯性开关的制作。玻璃无掩膜湿法腐蚀技术具有工艺简单、便于操作等优点,它的成功应用较好地满足了器件产业化的要求,为批量研制低g值微惯性开关提供了可靠的工艺基础。

The low-g micro inertial switch is a precision inertial device sensitive to the inertial acceleration and executing switch mechanical operation.In order to increase the product yield,the anti-stiction trapezium protrusion structure was utilized to solve the stiction problem in the process of wafer cleaning and drying.The anti-stiction structure with a size about 135 μm×135 μm×20 μm was fabricated in the bottom of the glass cover using the maskless Pyrex wet etching technique.The bad effects of surface tension and Van der Waals force were weakened by decreasing the contact area between the mass structure and the glass cover.Thus the stiction problem was successfully solved and the qualification rate of the low-g micro inertial switch chip in the process of wafer cleaning and drying was increased to about 95%.The low-g micro inertial switch with the anti-stiction structure was fabricated using the MEMS bulk Si micro-machining process and packaged in wafer level.The advantages of the maskless Pyrex-etching technique include the simple process and feasible operation.Its successful application meets the requirement of industrialization for the devices,providing a reliable fabrication process to produce low-g micro inertial switches in batches.