臺灣博碩士論文加值系統

摘要
當材料受到一週期性的反覆且變化之應力，將導致材料最終產生破壞的情形稱之為疲勞，在這種動態應力下產生的斷裂稱為疲勞斷裂。因材料的疲勞行為發生時並無任何明顯的外觀改變，而是一種潛在的行為，且沒有明顯的塑性變形區，對元件的安全以及壽命的影響更是無法明顯觀察並加以預防，因此可藉由疲勞試驗來預測元件之壽命，並進一步對元件進行防範和更替的動作。
本論文之疲勞實驗利用單軸向微拉伸試驗機針對銅薄膜之疲勞性質進行量測，實驗之試件設計U形彈簧與插栓等結構，以去除對準誤差的可能性，以確保壓電致動器所產生的拉伸力傳遞至懸浮薄膜時仍為單軸向力，再利用標準之無塵室製程製作試件。進行疲勞試驗前，先針對不同厚度之銅薄膜進行應力-應變關係之量測，求得其楊氏係數、降伏應力及最大應力…等值。本疲勞實驗中之邊界控制採用受力負載回授控制之方式進行量測，實驗中之銅薄膜維持於一個受力緊繃的狀態，並固定薄膜所承受之頻率與應力振幅，進行反覆週期性應力變化，並針對不同厚度之銅薄膜進行疲勞性質之量測。
實驗結果顯示，銅薄膜於不同厚度下之疲勞行為並無顯著性的差異，但在較低之平均應力有其明顯較長的週期形。

Abstract

Microelectromechanical systems (MEMS) technologies are developing rapidly with increasing study of the design, fabrication and commercialization of microscale systems and devices. While the primary function of the system rely on their electrical capability, the structure integrity of each component is essential for their overall performance and lone term reliability. As feature sizes of these devices continues to decrease, the performance and reliability concern increases. Therefore, accurate knowledge on the mechanical behaviors of thin film materials used for MEMS has become important for successful design and development of MEMS.
During operation of an MEMS, the bridge structures deflected. These deflections are anticipated to reach kHz frequencies and very high cycle numbers can be attained over short time periods. The lifetime prediction with increases in switch cycles is strongly dependent upon the device dimensions and characteristics of structural thin films. Thus, understanding of fundamental observed failure mechanism and mechanical response respected to external loads plays an important role in products design and lifetime prediction of MEMS.
Here , our study focuses on the fatigue property of the copper thin film using microtensile apparatus. The structure is satisfied this setup eliminate the possibility of aiming error and to meet the needs of this experiment. Before the fatigue test, copper thin-films with different thickness are being tested to obtain the relationship between force and strain, from which, Young’s modulus , yield stress, and max stress etc… can be obtained. The method of loading feedback control is used to control the boundary values in the fatigue experiment. In the experiment, the copper thin-films with different thickness were constantly kept under strain, and the force applied to them and the frequency of which was applied were kept constant for repeated testing.
We found copper thin-films with different thickness shows no significant difference under fatigue, but it was apparent that a long period in lower mean stress.

目錄
摘要..................................................ii
Abstract.............................................iii
目錄..................................................iv
圖目錄................................................vi
表目錄...............................................viii
第一章 序論.............................................9
1.1 研究目的..........................................9
1.2 研究動機..........................................10
1.3 材料的選擇........................................12
1.4 銅薄膜的沉積方式..................................12
第二章文獻探討..........................................14
2.1 導論..............................................14
2.2 薄膜機械性質試驗回顧..............................15
2.2.1 奈米壓痕法(nanoindentation)...................15
2.2.2 晶片彎曲法(wafer curvature)...................18
2.2.3 晶格常數應變量測法............................21
2.2.4 微型樑彎矩測試法(Microbeam bending test)......22
2.2.5 微拉伸試驗法(microtensile testing)............23
2.3 疲勞試驗..........................................28
2.3.1 疲勞理論概要..................................28
2.3.2 疲勞相關試驗方法..............................30
第三章 試件設計與設備架構...............................32
3.1 前言..............................................32
3.2 試件設計製作......................................32
3.2.1 試件結構設計..................................32
3.2.2 試件尺寸設計及模擬............................37
3.2.3 試件製程......................................40
3.3 微拉伸試驗機之架設................................43
3.3.1 設備架設目的..................................44
3.3.2 系統設計......................................44
3.3.3 系統荷重計之設計..............................46
3.3.4 設備整體架設整合..............................49
第四章程式編寫與實驗步驟................................51
4.1 前言..............................................51
4.2 實驗控制程式之設計................................52
4.2.1 拉伸試驗控制程式設計..........................52
4.2.2 疲勞試驗控制程式設計..........................53
4.2.3 疲勞試驗之回授控制程式設計....................54
4.2.4 程式整合以及資料儲存..........................56
4.3 實驗步驟及資料處理................................57
4.3.1 單軸微拉伸試驗實驗步驟........................57
4.3.2 單軸微拉伸試驗資料處理及運算..................58
4.3.4 單軸疲勞試驗實驗資料處理及運算................60
第五章結果與討論........................................62
5.1 前言..............................................62
5.2 量測結果..........................................62
5.2.1 銅薄膜於厚度900奈米下之單次軸向微拉伸試驗.....62
5.2.2 銅薄膜於厚度500奈米下之單次軸向微拉伸試驗.....64
5.2.3 銅薄膜之疲勞試驗..............................65
5.2.4 銅薄膜厚度500奈米與900奈米之疲勞性質比較......69
5.3 結論..............................................71
5.3.1 薄膜之單軸向拉伸試驗..........................71
5.3.2 薄膜之疲勞試驗................................74
5.4 未來與展望........................................77
參考文獻................................................78

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