- 學位論文
以微機電製程製作三氧化鎢薄膜苯氣體感測器之研發與感測性質研究
The Study of Fabrication and Gas Characteristics of MEMS-based Benzene Gas Sensor Incorporated in WO3 Films
摘要
隨著科技的進步，生活品質不斷的向上提升，室內環境的設計及裝潢已成為眾人所要求的項目。根據統計，人的一生中有90%的時間是待在廣義的建築室內空間中。在建築裝潢中所使用的材料、接合劑及塗料中皆含有揮發性有機化合物。其中會令人致癌的苯更是大量的充斥在生活環境中。如石化、橡膠、樹脂油漆、印刷、醫藥、塑膠、染料、汽油、一般室內裝潢空間等。由於苯被廣泛的使用，若沒有適當的苯污染防制措施，在長期的暴露下可能會引起健康危害。根據我國84年2月所修定之「勞工作業環境空氣中有害物容許濃度標準」，規定苯之八小時日時平均容許濃度為5ppm，而美國職業安全衛生署OSHA之標準為1ppm。 本文利用微機電（Micro-Electro-Mechanical Systems，MEMS）製程製作苯氣體感測器，其結構包含三氧化鎢（WO3）感測層、白金（Pt）加熱器及指叉電極。利用濺渡沉積三氧化鎢薄膜，經由退火處理來得到較為完整之結構，並用蒸鍍方式製作白金加熱器及指叉電極。實驗所得到之微型感測器原型則以測試在250℃、300℃及350℃不同工作溫度下其濃度與感測層電阻間相互之關係及感測器靈敏度測試，並討論其結果。 實驗結果顯示三氧化鎢薄膜確實會與苯產生作用而改變其電性，當濃度增加時其電阻值也會相對的做出降低的反應。感測器工作溫度操作在350℃時具有較高的濃度偵測極限值及較快的反應速度。但操作在350℃的感測器需要較長的時間達到穩定値，而穩定値跳動的範圍也較大。
並列摘要
Benzene （C6H6）is a highly important commercial chemical due to its chemical activity, high purity and relative cheapness. It is an organic compound that causes serious concerns in environmental health due to its toxicity and carcinogenic properties, even at low concentrations. The OSHA（Occupational Safety & Health Administration）has established a permissible Time-Weighted-Average exposure limit of 1 ppm. This paper describes the preparation of tungsten trioxide（WO3）thin films by the reactive RF magnetron sputter. The primary deposition parameters that influence the microstructure, chemical and electrical properties of WO3 thin films formed by reactive magnetron sputtering are substrate temperature, Ar/O2 concentration ratio, total pressure, and RF power. The films are then stabilized by annealing in dry air. The platinum catalytic filter were developed to enhance the sensitivity of tungsten trioxide to benzene. The characterists of their structural properties were presented by means of XRD measurements and the film morphology by the SEM microscope. The sensors were operated at the temperature range from 250 to 350℃ to analyse the effect of working temperature on their response. The present sensor shows good speed of response and highly detective limit of concentration at 350℃.