【作者】 张丹；

【导师】 丁桂甫；

【作者基本信息】 上海交通大学 ， 微电子学与固体电子学， 2008， 硕士

【摘要】 很多MEMS器件中都要用到电热微驱动器,电热微驱动的工作原理通常是:利用电阻发热使温度升高随后产生热膨胀,产生的输出力和输出位移来起到驱动作用。这些驱动器可以分为面外运动驱动器和面内运动驱动器,这一课题已被广泛研究。面外运动电热微驱动器通常运用的使双压电晶圆片效果来产生面外运动。通常为一双层结构,组成双层结构的两种材料的热膨胀系数彼此不同。当结构升温时,驱动器由于双层结构热膨胀程度的不同而弯曲。这一双层结构还可以被拓展为三层或多层结构的设计。多用金属材料,如Cu,Al,Ni,Au或者半导体材料Si,SiO2,Si3N4等作为结构材料。聚合物材料如SU-8光刻胶也被用作器件的结构材料。我们工作的基本思想是:运用聚合物SU-8和金属Ni作为驱动器的结构材料来制备面外运动电热微驱动器。由于聚合物SU-8的杨氏模量很小,硬度不大,难以产生与金属和半导体材料相当的输出力,为了弥补这一缺陷,我们设计了特殊的聚合物基包裹镍电阻丝的结构来弥补这一缺陷,同时又能很好地保持运用聚合物SU-8作为结构材料的优点:使工作温度降低,产生较大的输出位移,结构中不会存在内应力,同时可以大批量生产,工艺实现较简单,比起文献中用DRIE(深反应离子刻蚀)来制备驱动器的工艺方法成本较低,能量利用率较高,能耗低。本论文介绍了一种新型的面外运动聚合物基电热微驱动器。这一驱动器包含了双层结构,下层为聚合物SU-8包裹弯曲的Ni致热电阻丝形成的三明治结构,上层为Ni牵制层。驱动器结构为对称的。本论文讨论了它的结构设计,仿真优化,器件制备和测试。这一器件的尺寸为0.38mm×0.23mm,当被驱动时,产生面外运动。当加载电压为1.4V,功耗为20mW时器件可以实现11μm的最大驱动位移,此时器件的最高温度为100℃,器件有36 N/m的垂直方向的刚度,能产生0.56mN左右的面外输出力。更多还原

【Abstract】 MEMS components using thermal micro-actuators that use ohmic heating and consequent thermal expansion for actuation have been widely studied. They can be categorized as in-plane actuators and out-of-plane actuators. The out-of-plane thermal actuators which employed the bimorph effect to generate out-of-plane motion are usually bi-layer structure. Such a bi-layer actuator comprises two layers whose material thermal expansion coefficients differ from each other. When heated, the beam bends due to the different thermal expansion coefficients of the two layers. The bimorph structure can be extended to multilayer or multi-morph design , using metallic materials and semiconductor materials. Polymers have also been employed as the structure material.The basic idea of the work in this paper is that we realize out-of-plane motion by using polymeric SU-8 and metal Ni as materials. Multiple materials in the symmetric structure are employed to compensate the limitation of SU-8 who has low elastic modulus and cannot produce actuation force as silicon and metals do. However still hold benefits of using SU-8, which can perform large displacements at low temperatures. In addition, the fabrication has the potential for low cost through batch fabrication using bulk silicon micromachining, which is much cheaper than DRIE mentioned in the former literature. It may have some application under condition where power consumption is considered.An out-of-plane micro thermal polymer actuator, which is designed with the bimorph effect, is presented. This actuator has a bi-layer structure, which consists of SU-8 photo-resist encapsulating meandering nickel heater and passive Ni top layer. The actuator has a symmetric configuration. This paper demonstrates its design , simulation , fabrication and device tests. This actuator bends vertically when energized. With a size of 0.38mm×0.23mm, it demonstrated a maximal vertical displacement of 11μm at 1.4V driving voltage and at 20mW input power, at an average temperature of 95℃. The stiffness of the actuator is of 36 N/m along perpendicular direction, and it can generate a vertical force of 0.56mN in this direction.更多还原