Study on Fabrication of High Power Electrostatic Microactuators Using High Aspect Ratio X-ray Lithography

1.研究了紧凑型同步辐射光源高深宽比X射线光刻工艺条件的优化。在1996年春季安装的最小超导SR光源“Aurora”上建立了一条专门用于LIGA工艺的束线。在立命馆大学，并运作。建立了PMMA曝光显影的工艺条件，在曝光剂量分别为3A min和32A min的条件下，制备了200um深和100um深的PMMA微结构。2.制作了用于LIGA的X射线掩模。使用CAD系统设计掩模图案。X射线掩模由2微米厚的碳化硅薄膜和5微米厚的金吸收体组成，以优化X射线曝光的对比度。利用该X射线掩模曝光并研制了宽2微米、高200微米、纵横比为100的PMMA抗蚀剂结构，并利用电铸镍工艺制作了镍微结构。设计、制作了3.3维高功率微致动器。微驱动器的基本结构由作为固定电极和移动电极的Ni微结构、作为Ni种子层的Ni、作为隔离层的SiO_2和作为牺牲层的SiO_2以及Si衬底组成。镍微结构的尺寸为高度为100微米，最小线宽为2微米，最小间隙为2微米，最大纵横比为50。采用LIGA工艺，采用SR光源的高深宽比X射线光刻和电铸相结合的方法，制作了梳状驱动静电微驱动器和静电微摆动电机。分别在65V脉冲电压和125V-12相脉冲电压作用下，确定了梳齿驱动静电微驱动器和静电微摆动电机的运动。

1.Optimization of process conditions for high aspect ratio X-ray lithography (LIGA) using the compact synchrotron radiation (SR) light source has been investigated. An exclusive beam-line for LIGA process has been set-up on the smallest super conductive SR light source "AURORA", installed in 1996, spring. in Ritsumeikan Univ., and operated. Process conditions for exposure and development of PMMA, were founded, and PMMA microstructures of 200 mum-deep and 100 mum-deep were fabricated under exposing dosage of 3 A min and 32 A min.2.An X-ray mask for LIGA has been fabricated. Mask patterns were designed using a CAD system. The X-ray mask is consisted of 2 mum-thick SiC membrane and 5 mum-thick Au absorber in order to optimize contrast for X-ray exposure. Using the X-ray mask, PMMA resist structures with 2 mum-wide, 200 mum-high and aspect ratio of 100 were exposed and developed, and Ni microstructures were produced using Ni electroforming.3.3-D high power microactuators have been designed, fabricated and evaluated. The basic structure of microactuators is consisted of Ni microstructures as fixed electrodes and movable electrodes, a Ni seed layer, SiO_2 as an isolation layer arid a sacrificial layer, and Si substrate. Dimensions of Ni microstructures were height of 100 mum, minimum line width of 2 mum, minimum gap of 2 mum and maximum aspect ratio of 50. A comb-drive electrostatic microactuator and an electrostatic micro wabble motor were fabricated by LIGA process combined high aspect ratio X-ray lithography using SR light source and electroforming. The comb-drive electrostatic microactuator and electrostatic micro wabble motor were confirmed to move by applying 65V pulse voltage and 125V-12 phases pulse voltage, respectively.