本研究先將純銅在678°C (0.7 Tm)下退火12小時，消除試片在加工時產生的殘留應力，接著施加不同電流密度 (2×10^4 A/cm^2 ~ 3×10^4 A/cm^2)， 並在每次通電結束時用液態氮急速冷卻試片以保存通電當下的微結構。本研究發現在大部分的通電條件下，純銅之拉伸機械性質皆有提升，循環通電後其降伏應力最多提升89%；楊氏係數最多提升96.2%；極限抗拉強度最多提升6.5%，而伸長率在通電後造成最多5.5%的下降。後續利用電子背向散射衍射分析(Electron backscatter diffraction, EBSD)觀察到純銅因通電造成晶粒細化、差排密度增加、晶粒取向改變、雙晶比例提升等微結構改變，以及利用掃描式電子顯微鏡(Scanning Electron Microscope, SEM) 觀察到試片破斷面在通電後出現延展性下降之微結構變化。

Copper as the fine pitch circuit line material of advanced electronic packaging substrate will experience tensile stress during manufacturing as well as electronic application. Electromigration will induce electromigration force and Joule heat to the circuit line during electronic application. It is imaginable that electromigration will have impact on the mechanical properties and microstructure of the copper circuit. In this study, we investigated the effect of electromigration on the micro tensile mechanical property of pure copper, and the mechanism was explored by incorporating the microstructure evolutions. The pure copper specimens were pre-annealed at 678°C for 12 hours to reduce the residual stress generated during fabrication. The subsequent current stressing treatments at different current densities (2~ 3×10^4 A/cm^2) were found to enhance the yield strength up to 89%, Young’s modulus 96.2%, and ultimate tensile strength 6.5%, whereas degrade elongation by 5.5%. The electron backscatter diffraction analysis showed that non-deformation recrystallization occurred which induced grain refining and twin formation of Cu. The influence of dislocation, twin fraction, and grain orientation on the mechanical properties were investigated and discussed in the study. The athermal electron wind force effect found predominated over the thermal Joule heat on governing the microstructure variation and the mechanical properties.

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