臺灣博碩士論文加值系統

由於小尺寸及高整合等優勢，微機電麥克風在近年來迅速發展；雖然在製程上可與半導體製程相容，但在沉積、蝕刻等製程後，結構中的殘餘應力會使其產生非預期之形變，進而影響產品的穩定性。過去幾十年來，關於微機電元件之研究已臻成熟，但以製程模擬方法來估算製程結果的研究卻相當少見。本研究將製程模擬技術應用於有限元素分析中，提出分析電容式微機電麥克風的殘餘應力與預變形之方法。
薄膜之殘餘應力可細分為本質應力及熱應力。本質應力為製程相關參數，須由實驗得知，以做為有限元素模型分析之初始條件。本研究首先針對麥克風模型進行多層薄膜應力量測實驗，並於各層薄膜沉積後進行熱循環退火，結果指出薄膜在高溫退火後，其殘餘應力減小且薄膜特性趨於穩定；由製程產生於氧化矽及多晶矽之本質應力，將由壓縮熱應力改變至張應力及接近無應力狀態；此外，金屬鋁薄膜經由退火可降低本質應力，且當應力值到達塑性區後，其應力變化不明顯，因此在模擬中只需考慮鋁薄膜之熱應力。然而當鋁薄膜在次微米等級之厚度時，其材料強度相異於較厚之鋁金屬，有必要於模擬分析中考慮隨厚度而變之鋁薄膜材料參數，此參數可由文獻及實驗比對得到，以此模擬方法可適當表現出實際鋁薄膜的力學行為。
微機電麥克風之殘餘應力分析結果顯示，多晶矽振膜在承受壓應力或低應力情況下，製程結束後會有彎曲變形產生，將會造成麥克風共振頻率與靈敏度偏離設計值；藉由控制薄膜沉積與退火溫度有助於改善此現象，使其在薄膜蝕刻後保持微小張應力且平坦無變形。

中文摘要………………………………………………………………….i
英文摘要……………………………………………………………….iii
誌謝………………………………………………………………………v
目錄……………………………………………………………………..vi
表目錄…………………………………………………………………viii
圖目錄……………………………………………………………………ix
第一章、 緒論………………………………………………………1
1.1 微機電麥克風簡介………………………………………………1
1.2 研究動機…………………………………………………………3
1.3 文獻回顧…………………………………………………………4
1.3.1 電容式麥克風之發展…………………………………………4
1.3.2 薄膜材料特性與殘餘應力……………………………………5
1.3.3 製程模擬分析………………………………………………17
1.4 研究目標………………………………………………………18
第二章、 基礎理論…………………………………………………20
2.1 薄膜應力理論…………………………………………………20
2.2 薄膜應力之量測………………………………………………22
2.2.1 Stoney方程式………………………………………………22
2.2.2 薄膜應力量測之方法 …………………………………25
2.2.3 多層薄膜應力量測…………………………………………27
2.3 有限元素法基礎理論…………………………………………27
2.3.1 線彈性有限元素法理論基礎………………………………28
2.3.2 材料非線性有限元素法理論………………………………32
2.4 數值方法與收斂準則…………………………………………36
第三章、 研究方法…………………………………………………40
3.1 工研院微機電麥克風結構之組成與尺寸……………………40
3.2 多層薄膜殘餘應力量測實驗…………………………………42
3.2.1 多層薄膜殘餘應力量測實驗流程…………………………42
3.2.2 多層薄膜殘餘應力量測實驗結果…………………………47
3.3 有限元素分析方法……………………………………………51
3.3.1 製程模擬分析………………………………………………51
3.3.2 二維多層薄膜有限元素模型之建立………………………52
3.3.3 二維多層薄膜模型之邊界條件與負載設定………………54
3.3.4 微機電麥克風結構二維簡化模型之建立…………………56
3.3.5 微機電麥克風結構二維簡化模型之邊界條件與負載……57
第四章、 微機電麥克風模型製程模擬結果與討論………………59
4.1 二維多層薄膜結構之應力與翹曲行為分析…………………59
4.1.1 各層材料熱應力分析………………………………………59
4.1.2 多層薄膜沉積後晶圓翹曲行為……………………………62
4.1.3 加入本質應力於薄膜後之應力分析………………………66
4.2 鋁薄膜殘餘應力探討…………………………………………70
4.3 微機電麥克風結構二維簡化模型分析………………………75
4.3.1 鋁背板之殘餘應力與預變形分析…………………………75
4.3.2 多晶矽振膜之殘餘應力與預變形分析……………………76
第五章、 結論與未來展望…………………………………………81
參考文獻…………………………………………………………………86

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