近年來，印刷技術逐漸受到重視，其以創新設計的技術，將精密導線以直接印刷方式（Direct printing）進行導線製作在超薄、可撓式基板上，只要一台設備就可完成製程，故相較於步驟繁複及成本高昂的黃光蝕刻製程，超細導線印刷技術兼具了成本競爭力與環保優勢。可撓式基板材料為具有可連續捲對捲(Roll-to Roll)生產優勢的新世代基板技術，在材料上則需具備輕、薄、耐衝擊、不易破碎以及攜帶方便、可彎曲性之特性。而材料方面，奈米銀在經過燒結後有著很高的導電率，且奈米銀導線製程擁有高度的圖案可撓性、可大面積印刷以及低廉的製程成本；其中電遷移破壞數十年以來都是電子產品在高電流驅動之下的一種主流破壞機制。然而目前尚未有人針對印刷製程的奈米銀導線進行電遷移破壞的研究。而隨著電子產品的微縮，印刷電路中的導線尺寸將變得更加細長，其長寬比會激增，當元件通過一定電流時，由於微縮下的銀導線其截面積小，因此通過的電流密度會激增，電遷移破壞的驅動力與產生的焦耳熱也會跟著增強，進一步造成結構較為脆弱的印刷銀導線更迅速達到斷路的破壞，減短電子產品的使用壽命。本實驗建立的不同長度的銀導線在150°C的環境下施加1.5×10^5 A/cm^2的高電流密度架設電遷移測試，以了解電遷移對於印刷銀導線製程的影響以及其破壞機制與微結構的變化，並與傳統濺鍍製程的電遷移行為做比較以建立印刷製程的可靠度研究。

In recent years, printing technology is one of the promising patterning techniques in flexible electronic devices due to its low cost manufacturing process, reduction of waste materials, and large-area patternability. To date, silver nanopaste has mostly been used, because silver has the lowest resistivity among all the metals. Second, Ag nanoparticles are relatively easy to be formed into various sizes and shapes, and disperse well in a variety of organic solvent. Moreover, direct printing is capable of putting interconnects on flexible substrate. With the trend of miniaturization of electronic products, electronic packaging is shrinking dramatically year after year. Therefore, when a process is developed into fine-pitch conductive interconnects, electromigration (EM) associated with open-circuit failure could become a concern due to the increased current density, so there is an increasing significance of the reliability in the interconnect packaging. In this study, EM behavior of printed interconnects composed of silver nanoparticles was evaluated under a current density of 1.5×10^5 A/cm^2 at 150°C through in-situ resistance versus time measurement. During the EM test, the resistance of the interconnects increased and the morphologies of silver nanoparticles changed due to Joule heating generated under high current density, eventually causing failures of the interconnects. The interconnects with different lengths from 100 μm to 400 μm were also examined and discussed. In addition, the reliability of the printed interconnect would be compared to that of conventional deposited silver interconnect under the same condition.

摘要 I
Abstract II
Content III
致謝 VI
List of Figures VIII
List of Tables XVI
Chapter1 Introduction 1
Chapter2 Literature Review 3
2.1 Sintered silver nanoparticles 3
2.2 Electromigration 9
2.2.1 Electromigration phenomenon in metals 10
2.2.2 Back stress and critical length 14
2.2.3 Black’s equation 17
2.3 Current crowding effect 19
2.4 Joule heating 22
2.5 Percolation model for porous structure 24
Chapter3 Experimental Details 29
3.1 Specimen preparation 29
3.1.1 Structure design 29
3.1.2 Specimen fabrication 30
3.2 Experimental setup 34
3.2.1 Electromigration test 34
3.2.2 Joule heating measurement 37
3.2.3 Infrared camera observation 38
3.2.4 ANSYS simulation 41
Chapter4 Experimental Results 45
4.1 Microstructures of interconnects under different fabrication method 45
4.2 Joule heating measurement 49
4.3 In-situ Resistance versus time curves measurements 55
4.3.1 RVT curves of printed Ag interconnect 55
4.3.2 RVT curves of sputtered Ag interconnect 59
4.4 Microstructural evolution during electromigration test 62
4.4.1 Microstructural evolution of printed Ag interconnects 62
4.4.2 Microstructural evolution of sputtered Ag interconnects 70
4.4.3 EM test of sputtered interconnects considering different Joule heating 77
4.5 Isothermal sintering of printed interconnects 81
4.6 Infrared camera observation for temperature distribution 83
4.7 The ANSYS simulation 87
Chapter5 Discussions 95
5.1 Effect of back stress and length of Ag interconnect 95
5.1.1 Calculation of critical length 98
5.2 Effect of different fabrication of Ag interconnect 101
5.2.1 Effect of Joule heating 104
5.2.2 Modification of Joule heating and current density effect 105
5.3 Microstructures under isothermal sintering of printed interconnects 108
5.4 Resistance and microstructure changes of printed Ag interconnect 111
5.5 Resistance and microstructure changes of sputtered Ag interconnect 114
5.5.1 Calculation of atomic flux during electromigration test 116
Chapter6 Conclusions 119
References 121

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