Microactuators Composed of Silicon Microstructures with a Tunneling-current-Displacement Sensor

本研究的目的是在硅片上制作微微型运动机构和位移传感器，并获得与纳米级精度的位移传感器集成的微运动器件。本文重点研究了基于集成电路的多部件隧道电流单元的微加工技术。得到了以下结果：(1)对厚度约为10微米的硅薄膜进行了静电弯曲。膜片中心的位移被用作z方向执行器。用KOH对硅片进行了各向同性刻蚀。位移由静电位移传感器测量，并通过反馈回路进行控制。上升时间为1 ms，精度为100 nm。(2)基于能量原理推导出膜片变形的近似计算公式。实验值与理论曲线吻合。用该公式设计膜片执行器是可能的。(3)在膜片的中心固定一根锋利的钨针。膜片通过静电驱动来维持针和靶之间的间隙。间隙约为1 nm，检测到1 ~ 100 nA的隧穿电流。(4)制备了多晶硅薄膜静电致动器。驱动器将被用来驱动目标在平行于基板表面的X-Y平面上。一种驱动器具有梳状结构，具有重叠的齿作为静电驱动器。另一组在平行四边形挠性的两端安装平行板致动器。这些执行器是静电驱动的。制作了带有4个二级执行机构的AX-Y级工作台。

The purpose of this research is to fabricate a micro miniature moving mechanism together with a displacement sensor on a silicon wafer and to obtain micro motion devices integrated with the displacement sensor of nm-order accuracy. Especially, this study focussed on the IC-based micromachining of a tunneling current unit which is built of many components now. Following results are obtained :(1) A silicon diaphragm with thicknesses of around 10 mum was bent electrostatically. The displacement at the center of the diaphragm was utilized as a Z-direction actuator. The silicon wafer was etched an-isotropically with KOH. The displacement was measured by the electrostatic displacement sensor and controlled through the feedback loop. The rise time was 1 ms and the accuracy was 100 nm.(2) An approximate formula to calculate the deformation of the diaphragm was deduced based on the energy principle. Experimental values fit the theoretical curve. It is possible to design a diaphraghm actuator with the formula.(3) A sharp tungsten needle was fixed at the center of the diaphragm. The diaphragm was electrosatically driven to sustain the gap between the needle and a target. The gap was in the order of 1 nm and the tunneling current from 1 to 100 nA was detected.(4) Electrostatic actuators made of a poly-silicon thin film were fabricated. The actuators will be used to drive the target in a X-Y plane parallel to the substrate surface. One actuator had comb-like structures with overlapped teeth as an electrostatic drive. The other had parallel-plate actuators attached at two opposing end of a parallelogram flexture. These actuators were electorstatically driven. AX-Y stage with 4 of second type actuators were fabricated.