本研究主要探討以低成本研製三氧化二鑭(La2O3)奈米粒子感測層、金奈米粒子表面吸附、開發微型晶片型氣體感測器針對ppb等級的低濃度二氧化硫(SO2)氣體感測。藉由MEMS半導體製程技術在6吋晶圓的8cm*8cm裡可以製造1萬多顆晶片。單一氣體感測晶片尺寸只要0.65mm*0.65mm，比一顆芝麻還小。此感測器整合微加熱器及氣體感測電極。在微加熱器方面，Pt厚度300nm且功率維持10mW下，以熱影像儀量測後顯示可達300℃以上且加熱速率為毫秒(ms)等級，於感測層方面，首先以高真空的環境下於感測電極上沉積氧化鋅(ZnO)作為導電層其厚度約300nm左右，此ZnO導電層，可以更有效吸附三氧化二鑭(La2O3)奈米粒子。在研製三氧化二鑭(La2O3)奈米粒子感測層方面，以低成本超音波懸浮技術研製出具有奈米尺度大小的三氧化二鑭(La2O3)奈米粒子，透過電子顯微鏡觀察，此奈米粒子結構比表面積極高，有利於氣體之擴散及吸脫附反應，奈米粒子直徑約為20~30 nm，接近氣體感材料之理想尺寸。此外，為了增加奈米感測層之氣體感測效能，本研究藉由金奈米粒子成功降低感測溫度，達低耗能感測器

低濃度二氧化硫(SO2)氣體感測結果發現感測器在未吸附金奈米粒子之感測層以溫度342.2℃，在響應值的部分量測100ppb的二氧化硫(SO2)氣體，有25%以上的感測響應值，在500ppb的部分，也已經到達47%左右的高響應值。而在有吸附金奈米粒子之感測層以溫度260.8℃，量測100ppb的二氧化硫(SO2)氣體，有10%左右的感測響應值，在500ppb的部分，也已經到達24%左右的高響應值。以吸附金奈米粒子之奈米感測層在感測效率上最為突出，其靈敏度、響應速率最佳，且工作溫度相對較低。此優異特性主要可歸因於金奈米粒子良好散布於三氧化二鑭(La2O3)奈米粒子感測層之上，使感測材料可以在較低工作溫度下，促進大量氣體分子解離。由以上成果可知金奈米粒子吸附之三氧化二鑭(La2O3)奈米粒子感測層是一非常具有潛力之氣體感測材料。

This study mainly discusses the development of lanthanum trioxide (La2O3) nanoparticle sensing layer at low cost, the adsorption of gold nanoparticle surface, and the development of microchip gas sensor for low concentration sulfur dioxide (SO2) gas sensing for ppb level .With MEMS semiconductor process technology, more than 10,000 chips can be manufactured in 8cm*8cm of 6-inch wafers.The size of a single gas sensing chip is only 0.65mm*0.65mm, which is smaller than a sesame. This sensor integrates a micro heater and a gas sensing electrode.In terms of micro-heaters, the Pt thickness is 300nm and the power is maintained at 10mW. After measurement with a thermal imager, it can reach more than 300°C and the heating rate is in milliseconds (ms). For the sensing layer, the first is to use a high vacuum environment Deposit zinc oxide (ZnO) on the sensing electrode as a conductive layer with a thickness of about 300nm,This ZnO conductive layer can more effectively adsorb La2O3 nanoparticles. In the development of La2O3 nanoparticle sensing layer, La2O3 nanoparticles with nanometer-scale size were developed by low-cost ultrasonic suspension technology, and observed through an electron microscope. The particle structure is positively higher than the surface, which is conducive to the gas diffusion and absorption and desorption reactions. The diameter of the nanoparticles is about 20-30 nm, which is close to the ideal size of the gas-sensitive material. In addition, in order to increase the gas sensing performance of the nano-sensing layer, this study successfully reduced the sensing temperature by using gold nano-particles to achieve a low-concentration sensor

Low-concentration SO2 gas sensing results show that it is at the nano-sensing layer of 342.2℃,measuring 100ppb of SO2 gas has a 25% response, and at 500ppb, there is a 47% response. At 260.8°C, the sensing layer has adsorbed gold nanoparticles and measures 100ppb of SO2 gas, with 10% response, and at 500ppb, it also has 24% response. The nano-sensing layer that adsorbs gold nano-particles is most prominent in terms of sensing efficiency, its sensitivity and response rate are the best, and the operating temperature is relatively low. This excellent characteristic can be mainly attributed to the good dispersion of the gold nanoparticles on the La2O3 nanoparticle sensing layer, so that the sensing material can promote the dissociation of gas molecules at a lower operating temperature. From the above results, it can be known that the La2O3 nanoparticle sensing layer adsorbed by the gold nanoparticles is a very promising gas sensing material.

目錄
口試委員會審定書 #
誌謝 i
中文摘要 ii
ABSTRACT iv
目錄 vi
圖目錄 ix
表目錄 xii
第一章、緒論 1
1.1 科技與環境空氣的衝突 1
1.1.1 空氣品質指標(AQI) 1
1.1.2 二氧化硫(SO2)氣體對人體之危害 2
1.2 各式氣體感測器之介紹 3
1.2.1 電化學式氣體感測器 3
1.2.2 熱導式氣體感測器 4
1.2.3 觸媒燃燒式氣體感測器 4
1.2.4 紅外線吸收氣體感測器 5
1.2.5 固態電解質氣體感測器 5
1.2.6 光離子化氣體感測器 5
1.2.7 傳統半導體氣體感測器 6
1.2.8 各式氣體感測器優缺點比較 6
1.3 現有感測技術與問題 7
1.3.1 氣體感測器應用與市場 7
1.4 研究動機與目的 8
第二章、基礎理論與文獻探討 12
2.1 二氧化硫氣體(SO2)感測的研究與演化 12
2.2 奈米金觸媒對氣體感測的研究 12
2.2.1 奈米金催化 12
2.2.2 溫度的影響 13
2.3 二氧化硫氣體特性 14
2.4 三氧化二鑭材料特性 14
2.5 基本理論 15
2.5.1 能帶理論(Band theory) 15
2.5.2 德拜長度(Debye length) 16
2.6 金屬半導體氣體感測器 17
2.7 奈米材料特性 18
2.7.1 小尺寸效應(Small size effect) 18
2.7.2 表面與界面效應(Surface and interface effect) 19
第三章、實驗方法 20
3.1 實驗材料 20
3.2 實驗設備與分析儀器 20
3.3 晶片製造 22
3.3.1 矽基板&介電層 22
3.3.2 金屬附著層 22
3.3.3 微型化感測加熱器 23
3.3.4 半導體電阻式感測結構製程 23
3.3.5 鈍化保護介電層 23
3.3.6 硬遮罩層(Hard Mask) 23
3.3.7 低溫反應性離子蝕刻(Cryogenic DRIE) 23
3.3.8 ZnO薄膜導電層 23
3.3.9 晶片製程流程圖 24
3.4 超音波懸浮技術研磨奈米粉末 25
3.4.1 奈米粉末研磨流程 25
3.4.2 研磨參數 25
3.5 製備三氧化二鑭奈米粉末混和四氯化金的酒精溶液 33
3.6 奈米粉末點膠法 33
3.7 晶片打線接合Wire bonding 35
3.8 氣體感測平台 35
第四章、結果與討論 36
4.1 La2O3奈米結構之晶片型氣體感測器量測SO2氣體 36
4.1.1 感測器之操作電壓與溫度 36
4.1.2 不同溫度下感測器針對低濃度二氧化硫氣體之響應 37
4.1.3 粉末尺寸對低濃度二氧化硫氣體響應的影響 41
4.1.4 ZnO薄膜導電層與感測材料之電性 43
4.2 La2O3奈米吸附Au晶片型氣體感測器量測SO2氣體 44
4.2.1 四氯化金溶液加熱還原金奈米粒子 44
4.2.2 吸附Au奈米粒子之感測層HRTEM分析 45
4.2.3 感測器之操作電壓與溫度 46
4.2.4 溫度對低濃度二氧化硫(SO2)氣體響應的影響 47
4.3 感測器長時間量測SO2氣體的穩定性 51
4.3.1 以La2O3奈米結構之晶片型長時間量測SO2氣體 51
4.3.2 以La2O3奈米吸附Au晶片型長時間量測SO2氣體 52
4.3.3 感測器硫化現象 53
4.4 La2O3奈米結構之晶片型氣體感測器其他氣體之響應 55
4.4.1 溫度對一氧化碳(CO)氣體響應的影響 55
4.4.2 溫度對二氧化碳(CO2)氣體響應的影響 56
4.4.3 溫度對二氧化氮(NO2)氣體響應的影響 57
4.5 La2O3奈米吸附Au晶片型氣體感測器其他氣體響應 58
4.5.1 溫度對一氧化碳(CO)氣體響應的影響 58
4.5.2 溫度對二氧化碳(CO2)氣體響應的影響 60
4.5.3 溫度對二氧化氮(NO2)氣體響應的影響 61
4.6 奈米感測層晶片型氣體感測器製備與厚度TEM分析 62
4.7 奈米結構系列晶片感測特性探討 64
4.7.1 ZnO薄膜層與La2O3的奈米粉末感測層特性探討 64
4.7.2 氣體與感測器之響應探討 65
第五章、結論與未來展望 69
5.1 結論 69
5.2 未來展望 69
參考文獻 70

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