熱制動微閥與微流量感測器之研究

Abstract

在微機電的領域中，熱制動的微閥及微流量感測器是非常有發展價值及潛力的，它們的制動範圍大、感測能力精確、元件體積小，且消耗的功率也小，並能整合成為一個微流量控制系統。 本論文中探討以白金為加熱電阻的微閥製程，微閥的主要結構是由白金/二氧化矽/矽薄膜的三明治結構組成。利用三者膨脹係數的不同，可藉由加熱使薄膜彎曲，因此，我們可以在以白金做成的電阻絲，加入電壓使其發熱造成薄膜彎曲來控制元件動作。在微流量感測器方面，我們是利用金屬電阻對溫度變化的敏感度，偵測出流量大小，在此我們也是利用白金當作電阻，一方面與微閥製程相符合，一方面白金的電阻溫度係數 (TCR) 也較高。 在本篇論文中，將提出薄膜式熱制動微閥及微流量感測器的運作機制及設計考量，討論元件的製程技術，並對結果作一些探討，最後對元件性能之提升及未來研究方向提供一些建議。

Thermally actuated microvalves and micro-flow sensors are very potential in the field of MEMS. They are small devices with large actuation range, low power consumption and precise sensing ability. Besides, they can be integrated to construct a micro flow control system. The main structure of a microvalve is a sandwich diaphragm which consists of Pt, SiO2 and Si layers. The microvalve buckles due to the different thermal expansion of these materials. The microvalve is controlled by an input voltage to the platinum heater. In the micro-flow sensor, the sensing mechanism is that the resistance of a material varies with the change of temperature. This variance is called the temperature coefficient of resistivity (TCR). We also choose Pt as the sensing material owing to its high TCR. In addition, it is easy to integrate the micro-flow sensor with the microvalve by the same manufacturing processes. In this thesis, we propose the mechanisms and design considerations of the microvalve and the flow sensor. Fabrication process and results are discussed. Some suggestions are also given to promote the performance of the system.