【摘要】 为了解决深刻蚀绝缘体上硅(silicon on insulator,SOI)材料时存在的横向刻蚀(Footing)效应,在背腔释放SOI微机电系统(micro electro mechanical system,MEMS)工艺基础上,提出并实现了一种改进的利用背面保护电极抑制Footing效应的工艺方案.在SOI圆片上生长SiO2和Si3N4掩模材料并图形化后,背面腐蚀支撑层Si至掩埋层SiO2.去除掩埋层SiO2后,完成正面Al电极和背面保护Al电极的溅射.深反应离子干法刻蚀SOI圆片形成结构,再腐蚀背面Al薄膜完成结构释放.基于该工艺,对结构层厚度为80μm的采用双端固支梁的SOI微加速度计的结构进行设计与仿真、器件加工和最终的性能测试.加速度计在±1 g(g=9.8 m/s2)范围内的灵敏度和非线性度分别为106.7 mV/g和0.1%.实验结果表明,该改进工艺方案可以有效抑制Footing效应对器件结构的损伤,提高加工的可靠性.更多还原

【Abstract】 To deal with the Footing effect in deep etching of silicon on insulator(SOI) materials,a modified anti-Footing technique using backside protecting electrode based on backside-releasing SOI micro electro mechanical system(MEMS) process was proposed and implemented.SiO2 and Si3N4 were deposited on SOI wafer and patterned to be used as etching mask,and then the handle wafer was etched from backside to the buried oxide SiO2.After the buried oxide SiO2 was removed from backside,aluminum films were sputtered on the frontside for interconnection and in the cavity to prevent Footing effect.SOI wafer was etched with deep reactive ion etching(DRIE) and a structure layer was obtained,which was then released through etching of the thin Al film on the backside.Based on the proposed process,an SOI micro-accelerometer with double clamped beams and with the thickness of structure layer of 80 μm was designed,simulated,fabricated and its performance was tested.The scale factor and nonlinearity of the fabricated accelerometer were measured to be 106.7 mV/g(g =9.8 m/s2) and 0.1% from-1 g to 1 g,respectively.Testing results indicate that the modified technique can effectively prevent the device from damage of Footing effect,hence improving the reliability of the fabrication process.更多还原