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

本研究的目的是在硅片上制作一种带有位移传感器的微小型移动机构，并获得集成了纳米级精度的位移传感器的微动器件。特别是针对目前由多个元器件组成的隧道电流单元的集成电路微加工进行了研究。得到以下结果：(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向致动器。硅片用氢氧化钾进行了各向同性的刻蚀。通过静电位移传感器测量位移，并通过反馈回路进行控制。上升时间为1ms，精度为100 nm。(2)根据能量原理，推导了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)在膜片中心固定一根锋利的钨针。横隔膜被静电驱动以维持针和靶子之间的间隙。器件的禁带宽度为1 nm量级，隧道电流为1~100nA。(4)制作了多晶硅薄膜静电驱动器。致动器将用于在平行于衬底表面的X-Y平面上驱动目标。其中一个执行器具有梳状结构，带有重叠的牙齿作为静电驱动。另一种是在平行四边形弯曲的两端安装平行板致动器。这些致动器是由静电驱动的。制作了具有4个第二类致动器的AX-Y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.