臺灣博碩士論文加值系統

本研究利用標準0.18 μm CMOS製程製作出整合型氣體微感測器陣列晶片。此晶片上整合了四個氣體感測器、四個輸出電路與溫度計。本研究的目的在於利用此整合型氣體微感測器晶片，檢測四種揮發性有機氣體 (VOC)、環境濕度與溫度。此整合型晶片經由標準CMOS製程製作完成後，需進行後製程處理，利用蝕刻液將梳指狀電極間的二氧化矽犧牲層蝕刻移除，使梳指狀電極裸露出來，並將感測薄膜披覆於經過濕蝕刻處理後的梳指狀電極上。此整合型氣體微感測器陣列晶片的感測薄膜為氧化鐵、氧化銅、氧化錫、氧化鋯與氧化鋅，分別對丙酮、甲醇、乙醇、氨氣與水汽具有良好的響應特性。感測薄膜的特性分析是利用場發射掃描式電子顯微鏡 (FE-SEM)對薄膜表面型態與晶粒尺寸作分析；定性化學成份分析則是利用能量散射光譜儀 (EDS)與X光繞射儀 (XRD)對薄膜進行材料成分分析。
實驗結果顯示，利用水熱合成法製備而成的感測薄膜，其表面型態呈現高接觸表面積與高孔隙度，此特性有助於增加氣體微感測器的響應特性。此氣體微感測器陣列晶片對四種揮發性有機氣體 (丙酮、甲醇、乙醇、氨氣)與水汽分別具有高響應特性與選擇性。揮發性有機氣體微感測器的響應特性隨著環境中的相對濕度增加而提升。氣體微感測器整合電路量測部分，透過晶片上之環狀震盪電路，成功的將感測薄膜吸附目標氣體後所造成的的電容變化，轉換成頻率輸出變化。此整合電路的氣體微感測器的響應特性約為0.4-1.1 MHz/ppm。本研究進一步將此整合型氣體微感測器陣列晶片於混合揮發性有機氣體氣體的環境中進行特性量測。量測結果顯示，各個揮發性有機氣體微感測器仍然可以在混合氣體的環境中鑑別專一的目標氣體，實現即時偵測多種氣體的目標。

This study illustrates an integrated gas microsensors array chip fabricated using the standard 0.18 μm CMOS (complementary metal oxide semiconductor) process. The chip includes four gas sensors, four readout circuits and thermometers. The objectives of this study are to utilize the integrated gas microsensors array chip to detect four kinds of volatile organic compound (VOC) gases, the relative humidity of the surroundings and the ambient temperature. After completion of the CMOS process, the chip requires a post-process to etch the sacrificial layer between the interdigitated electrodes and to coat the sensitive film on the electrodes. The sensitive films of integrated gas microsensors array chips are α-Fe2O3, CuO, SnO2, ZrO2 and ZnO, which have good responses for detecting acetone, methanol, ethanol, ammonia and humidity gases, respectively. The characterizations of the sensitive films are observed using a field-emission scanning electron microscope (FE-SEM) to investigate the surface morphology and grain size. Energy dispersive spectrometry (EDS) and x-ray diffraction (XRD) are employed to estimate the chemical component analysis.
The experimental results show that the sensitive films synthesized by the hydrothermal method can help the gas microsensors enhance the response due to a high surface-to-volume ratio and high pore density. The gas microsensors array chip has a high response and good selectively for detection of VOC gases. The response of VOC microsensors decreased as the relative humidity of the ambient increased. In the measurement of the gas microsensors integrated with the circuit, the ring oscillator circuit successfully converts the capacitance variation of the microsensors into the oscillation frequency output. The response of the gas microsensors integrated with the circuit is about 0.4-1.1 MHz/ppm. This study further measures the characteristics of the integrated gas microsensors array chip in an environment with multiple VOC gases (acetone, methanol, ethanol and ammonia). Measurement results demonstrate that these VOC microsensors can identify the target gases in multiple gas environments and realizes the objectives of real-time detection.

致謝 i
中文摘要 ii
Abstract iii
Table of Contents v
List of Tables vii
List of Figures viii
Chapter 1. Introdution 1
1.1 Background 1
1.2 Previous Work 3
1.3 Objective 6
Chapter 2. Structure of the gas microsensors array chip 8
2.1. Design of the gas microsensors 9
2.2. Design of the thermometer 13
2.3. Design of the readout circuit 15
Chapter 3. Synthesis of the sensitive filmls 29
3.1. Adsorption mechanism of the gas sensors 30
3.2. Preparation flow of the Sensitive films 33
3.2.1. Acetone sensitive material 33
3.2.2. Methanol sensitive material 36
3.2.3. Ethanol sensitive material 39
3.2.4. Ammonia sensitive material 42
3.2.5. Humidity sensitive material 45
Chapter 4. Fabrication of the gas microsensors array chip 48
4.1. Process flow of the gas microsensors array chip 49
4.2. Package of the gas microsensors array chip 52
Chapter 5. Measurement equipments set-up 54
5.1. Experimental equipments set-up 54
5.2. Measurement of the polysilicon heater 56
5.3. Measurement of the thermometer 58
Chapter 6. Experiments of the gas microsensors array 59
6.1. Testing acetone microsensor 59
6.2. Testing methanol microsensor 67
6.3. Testing ethanol microsensor 71
6.4. Testing ammonia microsensor 75
6.5. Testing humidity microsensor 79
6.6. Testing gas microsensors array 84
Chapter 7. Conclusions and future works 92
7.1. Conclusions 92
7.2. Future works 93
References 94
Resume 99

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