矽薄膜式電熱制動微閥

Abstract

在微小機電系統領域的微小制動器研究中, 由熱制動的積體微閥是非常 有價值和發展潛力的, 因為它的設計較其他種類的微閥簡單, 制動範圍 大, 元件體積小, 消耗功率也小, 並且能和其他感測元件, 如壓力或流量 感測器, 以積體化技術製造成壓力或流量控制器. 在我們的設計中, 此 微閥主要結構是由多晶矽/ 二氧化矽/ 矽薄膜組成, 利用熱膨脹係數的不 同, 可藉由加熱使薄膜彎曲. 因此, 可以簡單的在多晶矽作成的電阻絲加 入電壓使其發熱來控制元件的動作. 除此之外, 由熱制動的微閥也有利於 元件的縮小化製造, 並達到更好的功能表現. 在這篇論文中, 我們將提出 薄膜式熱制動微閥的製程方法, 討論元件的製程考量, 製程技術以及實驗 的結果, 並對元件性能的提昇及應用作一些分析與建議. In the research of microactuators in the Micro-Electro- Mechanical-System(MEMS), thermal actuation of integrated valve structure is valued and attractivedue to the relative simplicity of actuator design, the larger actuation range,the smaler dimension allowed, the relatively low total power required and integratable with other sensing components,such as flow or pressure sensors,to fabricate a flow or pressure controller. The structure of this microvalve we propose consists of polysilicon/SiO2/ Silicon membrane sandwich. With the different coefficients of thermal expansion in the sandwich structure, the membrane buckles due to the increase of temperature. We can easily control the actuation by supplying electric voltage. Besides, for very small structures, thermal actuation becomes more attractive due to the geometrical advantages of scaling down. In this thesis, a membrane-type micromachined silicon micro-valve hasbeen developed. The design considerations, the fabrication process and the experimental results are discussed.