基于静电驱动的平行平板型微反射镜的研制  

Development of Parallel-Plate Micro-Reflector Based on Electrostatic Actuation

作　　者：吴嘉琦 赖丽燕 李以贵 Wu Jiaqi;Lai Liyan;Li Yigui(School of Science,Shanghai Institute of Technology,Shanghai 201418,China)

机构地区：[1]上海应用技术大学理学院,上海201418

出　　处：《微纳电子技术》2023年第6期924-930,共7页Micronanoelectronic Technology

基　　金：国家自然科学基金(62104151);上海应用技术大学引进人才基金(YJ2021-59)。

摘　　要：设计了一种基于静电驱动的平行平板型微反射镜,主要由镜面、下电极、支柱和玻璃基板构成。通过有限元模拟分析得到的仿真结果表明,带孔结构的微镜模型模拟位移量是传统双横梁支撑结构微镜模型的1.5倍,确定了制备的微镜装置结构。在制备过程中只采用了溅射、光刻、机械切割及反应离子刻蚀等工艺,简化了工艺流程,降低了制备成本。使用反应离子刻蚀(RIE)去除牺牲层,为了克服光刻胶OFPR800灰化速度慢、灰化时间过长会损伤器件的问题,提出添加氟类气体的解决方法。实验结果表明,使用O_(2)和SF_(6)混合气体作为刻蚀气体刻蚀牺牲层后,射频(RF)溅射成的铝膜平均表面粗糙度为5.33 nm,均方根粗糙度为7.44 nm,在250~850 nm的波长范围内能够得到70%以上的反射率,并且无光刻胶的残留,刻蚀效果最理想,因此采用了O_(2)/SF_(6)RIE工艺去除牺牲层。针对仿真中出现镜面层厚度变化影响驱动位移的现象,制备了镜面层厚度分别为0.5和0.8μm两种微镜样品进行了测试。实验结果表明:0.5μm厚的样品不能承受自重而凹陷,0.8μm厚的样品镜面驱动位移接近0.1μm,符合设计要求。A parallel plate micro-reflector was designed based on electrostatic actuation.It mainly consists of the mirror surface,lower electrode,pillar and glass substrate.The simulation results obtained through finite element simulation analysis show that the simulated displacement of the micro-mirror model with the hole structure is 1.5 times that of the traditional two-beam support structure micro-mirror model.And the structure of the micro-mirror device to be prepared was determined.Only sputtering,photolithography,mechanical cutting and reactive ion etching were used in the preparation process,thus the process flow was simplified and the preparation cost was reduced.Reactive ion etching(RIE)was used to remove the sacrificial layer.To overcome the problem that the photoresist OFPR800 has a slow graying speed and damage of the device causes by too long graying time,the solution of adding fluorine gas was proposed.The experimental results show that the average surface roughness of the aluminum film formed by radio frequency(RF)sputtering is 5.33 nm after using the mixture gas of O_(2)and SF_(6)as the etching gas to etch the sacrificial layer.Besides,the root-mean-square roughness is 7.44 nm,and the reflectance of above 70%can be obtained in the wavelength range of 250-850 nm,and there is no residual photoresist,thus etching effect is the best.Therefore,O_(2)/SF_(6)RIE process was adopted to remove the sacrificial layer.In order to explore the phenomenon that the thickness of mirror surface layer affects the driving displacement,two kinds of micro-mirror samples with the mirror surface layer thicknesses of 0.5 and 0.8μm were prepared for testing.The experimental results show that the 0.5μm thick sample can not bear the dead weight and sag,and the mirror surface driving displacement of the 0.8μm thick sample can be approximate to 0.1μm,satisfying the design requirements.

关 键 词：微电子机械系统(MEMS) 微反射镜 静电驱动 平行平板型 玻璃基板 

分 类 号：TH703[机械工程—仪器科学与技术]