臺灣博碩士論文加值系統

本研究利用微機電技術設計並製作微型半導體式氧氣感測器，其主要目的是要應用於新生兒能量消耗之量測。為了與IC製程相容，感測器以矽作為底材，並包括了加熱器、絕緣層、電極、感測層及蝕刻停止層，共5層結構。
在製程上，以佈植硼離子的多晶矽做為加熱電阻，使感測器達到最佳的操作溫度，再以二氧化矽薄膜做為加熱器與感測層間的絕緣層，而最重要的感測層，則是以佈植2 wt%鋰原子的二氧化錫做為感測材料。為了減少元件的消耗功率，最後再以KOH背部蝕刻出懸空結構。
經測試結果顯示，本研究所製作的加熱器，其消耗功率需220 mW，就可使感測器達到150℃的最佳操作溫度。可感測的氧氣濃度範圍在21%至50%之間，且以10分鐘的量測時間最為理想，其感測層的電阻相對變化量與氧氣濃度幾乎呈線性關係，可符合臨床上所需的應用。

The objective of the study is to design and develop a semiconductor-type oxygen gas sensor for a microscopic energy consumption measurement system, which will be used for monitoring of health condition of premature babies. The sensors are fabricated on silicon substrates using MEMS technologies and compatible with IC process. The device consists of five major components, including a micro-heater, an isolator, conducting electrodes, a sensing film and an etching-stop layer.
Doped polysilicon resistor is used as a heater to make the sensor operate at an appropriate temperature, resulting in a better sensitivity to the oxygen gas. Then a layer of silicon oxide is sputtered as an electrical isolator between the heater and the sensing layer. Lastly, the sensing film, tin-dioxide doped with 2wt% Li, is deposited. In order to minimize power consumption, a suspended membrane is formed by backside-etching of Si using KOH.
Experimental data show that the micro-heater can heat the membrane up to 150℃ by applying 220 mW. The oxygen sensor can successfully detect oxygen gas with the concentration ranging from 21% to 50%. It is found that the relative change of resistance is linearly proportional to the oxygen concentration while measuring time is 10 minutes. The developed sensor is suitable for clinical applications in the hospital.

摘要...........................................................................................................i
Abstract...................................................................................................ii
誌謝.........................................................................................................iii
目錄..........................................................................................................v
表目錄...................................................................................................viii
圖目錄.....................................................................................................ix
符號說明..............................................................................................xiv
第一章緒論.......................................................................................1
1.1 前言..............................................................................................1
1.2 研究動機.......................................................................................1
1.3 文獻回顧......................................................................................4
1.3.1 氧氣感測器的型式介紹....................................................................... 4
1.3.2 半導體式氧氣感測器之材料應用....................................................10
1.4 研究方法與架構.........................................................................12
第二章理論基礎........................................................................... 13
2.1 二氧化錫的材料性質.................................................................13
2.2 二氧化錫的氣體感測機制..........................................................14
2.2.1 氣體吸附機制........................................................................................14
2.2.2 氧氣的吸附...........................................................................................16
2.2.3 還原氣體的吸附..................................................................................18
2.2.4 水氣的吸附...........................................................................................19
2.3 催化劑的作用............................................................................20
第三章感測器之設計................................................................... 23
3.1 加熱器的設計.............................................................................24
3.1.1 加熱電阻的材料選擇...........................................................................24
3.1.2 電阻的計算............................................................................................25
3.1.3 摻雜與退火...........................................................................................26
3.2.電極與絕緣層的材料選擇..........................................................29
3.2.1 電極的材料選擇....................................................................................29
3.2.2 絕緣層的材料選擇...............................................................................29
3.3 感測層的材料選擇......................................................................30
3.4 感測器的結構設計......................................................................31
第四章感測器之製作................................................................... 34
4.1 製程技術介紹.............................................................................34
4.1.1 光罩設計與製作..................................................................................34
4.1.2 微影技術...............................................................................................35
4.1.3 薄膜沉積（Thin Film Deposition）技術.........................................38
（1）化學氣相沉積（CVD） .....................................................................38
（2）物理氣相沉積（PVD） .....................................................................40
4.1.4 蝕刻.........................................................................................................42
4.2 感測器之製作流程......................................................................43
1、晶片的清潔： ...........................................................................................45
2、晶片的準備： ...........................................................................................45
3、第一層光罩：定義背部蝕刻圖案........................................................46
4、第二層光罩：定義加熱電阻圖案........................................................47
5、第三層光罩：定義絕緣層圖案.............................................................47
6、第四層光罩：定義電極圖案.................................................................48
7、第五層光罩：定義懸橋式圖案.............................................................49
8、矽晶片背部蝕刻： ..................................................................................49
9、濺鍍上二氧化錫薄膜：..........................................................................49
4.3 氧氣感測器之切割與封裝..........................................................51
4.4 製程討論.....................................................................................53
4.4.1 光罩繪製的技巧：...............................................................................53
4.4.2 蝕刻控制............................................................................................54
第五章結果與討論....................................................................... 56
5.1 加熱器的量測.............................................................................56
5.2 實驗架設....................................................................................58
5.2.1 量測系統介紹........................................................................................59
5.2.2 氧氣濃度的控制方法...........................................................................59
5.3 對氧氣感測之結果......................................................................62
5.3.1 最佳操作電壓........................................................................................62
5.3.2 最佳量測方式........................................................................................63
5.3.3 上升曲線.................................................................................................65
5.3.3 量測時間.................................................................................................69
5.3.4 量測氧氣變化........................................................................................70
第六章結論與未來展望.............................................................. 72
6.1 結論............................................................................................72
6.2 未來展望.....................................................................................73
參考文獻.............................................................................................. 75
自述....................................................................................................... 82

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