整合氮化鉭微加熱平台之液相沈積二氧化錫氣體感測器的設計、製作與測試

Abstract

本論文以微機電技術設計與製造硫化氫氣體感測器，使用氮化鉭作為微加熱平台，並利用液相沈積法成功的將二氧化錫薄膜沈積至微加熱平台上。氮化鉭微型加熱器的優點在於幾何形狀設計簡單，便能達到低功率消耗、均勻的熱分佈、快速的熱響應時間與工作溫度可達到700℃以上。在氣體感測器設計方面，設計了三種不同的感測薄膜面積，且不同的感測器又設計了三種懸浮薄膜與加熱器邊長比。本論文中對於微型加熱器與薄膜特性方面，進行了功率消耗、熱分佈、熱響應、氣體響應特性與可靠度測試等量測。經實驗證明當感測薄膜面積為100μm×100μm且比例為2.5倍時，氣體感測器具有最低的消耗功率與較高的靈敏度等特性。另外，本實驗亦利用浸泡方式於感測薄膜表面添加銅，以提升感測器對於硫化氫氣體之選擇性與靈敏度，並且有助於降低工作溫度與消耗功率。

In this study, the design and fabrication of a micromachined LPD-based SnO2 gas sensor integrated with TaN micro-hotplate was carried out by utilizing MEMS technology. The advantage of TaN micro-heater is easy to design the geometrical shape. However, it could obtain many attractive characteristics, such as low power consumption, uniform thermal distribution, fast thermal response and high working temperature up to 700℃. In the design of the gas sensors, three different sensing film areas and, furthermore, three different edge length ratios of the membrane to micro-heater corresponding to each sensing film area are designed. In the characteristics of the micro-heater and sensing film, power consumption, thermal distribution, thermal response, gas sensing response and reliability were measured. Experimental results indicate that the optimum sensing film area and edge length ratios of the membrane to micro-heater are 100μm×100μm and 2.5, respectively, due to their low power consumption and high sensitivity. Besides, the experiment uses soaking on sensing surface to add copper to improve the selectivity and sensitivity of the sensors on hydrogen sulfide, and lower the working temperature and power consumption.