矽薄膜作為質子交換膜於微型燃料電池之製程/特性研究

Abstract

質子交換膜燃料電池被認為是在二十一世紀中最乾淨且有效率的替代能源技術之一，為了維持較長的使用時間與輕重量的需求，傳統電池已經無法再縮小體積來提供電力，而克服這些限制的一個可能的解決辦法就是使用可提供更大功率密度的微型燃料電池，矽晶片的微加工技術是降低燃料電池架構至微米尺寸的一個重要工具。 在本實驗中，以矽晶片為基材做成薄膜並填充Nafion® 已經被作為質子交換膜應用於微型燃料電池上，製造過程中利用微加工技術，包括曝光顯影技術(Photo-lithography)、電漿輔助化學汽相沉積(PECVD)、乾式蝕刻與濕式蝕刻。矽薄膜的尺寸大約是1平方公分，在此範圍內，有100個微米級的小洞。為了減少填充Nafion® 時表面張力的影響，每個小洞的剖面圖呈現倒金字塔的形狀，底部尖端的開口大小約500微米。此技術結合了Nafion® 所擁有的良好質子傳導率與矽薄膜相對容易整合的優點。

The polymer electrolyte membrane (PEM) fuel cell is considered to be one of the most promising clean and efficient alternative energy technologies of the 21st century; when it is used with sustainable hydrogen source. Conventional batteries are already unable to deliver power in more and more shrunk volumes maintaining the requirements of long duration and light weight. A possible solution to overcome these limits is the use of miniature fuel cell which offers a greater energy density compared to conventional batteries. The micromachining technology of silicon is an important tool to reduce the fuel cell structure to micrometer size. In this paper, the membranes based on silicon substrate filled with Nafion® have been fabricated as a proton exchange membrane for miniature fuel cells. This fabrication utilizes the micromachining procedures including photo-lithography, plasma-enhanced chemical vapor deposition (PECVD), and dry and wet etching processes. The device size of the silicon membrane filled with Nafion® was 1 cm × 1 cm. Within this 1 cm2 area, a total of 100 micro pores were fabricated. The cross-sectional shape of each pore was an inverse pyramid structure with a tip dimension of less than 500 nm to improve its mechanical strength and to enhance its surface treatment process. This technique combines the advantages of Nafion® with a good proton conduction and silicon membrane such as easy serial and parallel integration, respectively.