本研究使用銀奈米漿料熱壓製備銀導線。相較於傳統微影蝕刻及鍍膜製程，以奈米銀漿料熱壓製程之導線會有較多殘存孔洞(孔隙率>5%)。本論文將探討不同熱壓參數對銀導線之孔隙率、電阻之影響，並配合高荷電實驗、中斷實驗探討此多孔結構於通電後之溫度、電阻、表面形貌以及顯微結構之影響。 於不同熱壓參數下(溫度:200℃、250℃,壓力0MPa、5MPa、10MPa)，孔隙率及電阻率大致隨溫度及壓力上升而下降，此外機械性質亦隨熱壓溫度提升而有所提升，然而在250℃,5MPa之熱壓條件下，已足夠使奈米銀漿料形成高緻密性(6.2%)以及低電阻率(2.94*10-8Ω-m)之奈米銀導線，因此選用此熱壓參數進行高溫-高荷電測試。
於溫度200 ℃及105A/cm2電流密度進行高溫-高荷電測試後，可發現250℃,5MPa樣品於中段形成斷路並使線路失效。若觀測剖面顯微結構，可發現靠近失效點附近之孔隙率高達30.5%。此外可觀察到陰極之孔隙率上升5.8%，陽極孔隙率相對下降6.5%。若根據電阻變化可觀測到通電50hr內電阻已有劇烈變化，推測電遷移現象可能已經發生。而從溫度變化可知中段位置形成熱點，也說明了溫度對於原子擴散有所幫助並導致了最終於中段形成失效。
為了進一步了解銀漿料熱壓導線之電遷移機制，本研究分別進行28、40及200小時之中斷實驗。當通電至28及40hr，可以分別觀察到陰極孔隙率由6.8%上升至7.9%及8.2%，至於陽極孔隙率則由6.5%下降至3.5%及2.9%，說明電遷移效應會對孔洞結構造成影響並且於小於28小時內即開始發生。於通電中期(200hr)可以觀察到中段位置孔洞串聯情形，其孔隙率由8.2%上升至17.4%，而陰陽極之孔隙率變化也更為明顯。整合上述，可觀測到陰陽極的電遷移現象是發生在較早的時間，而隨著通電時間拉長，中段位置會因高電流密度而逐漸失效。此外，中段位置因電阻較高，可觀測到熱點存在，亦不排除有熱遷移甚至熔融現象發生。

For interconnects fabricated by the hot-pressing technique with silver nanoparticle paste, internal pre-existing pores exist (porosity > 5%). However, internal-pore structure is expected to change during current stressing. Therefore, cross-sectional observation is conducted to investigate the electromigration.
Paste PM03-α was the silver nanoparticle paste used in this research. Porosity and resistivity of the samples made in different hot press temperatures and pressures were compared, after which the sample with adaptable parameters was selected to conduct current-stressing tests. The parameters of the current stressing test were 105 A/cm2 and 200℃, while the modes of the test included failure and interruption experiments.

The hot press temperature and pressure of 250℃ and 5MPa were found to be sufficient to fabricate low porosity(6.2%) and low resistivity (2.94*10-8Ω-m) interconnects, so these parameters were selected to conduct the current stressing test. In the failure test, the middle site of the interconnect became the failure site and the hot spot site. In the interruption test, when the current-stressing time passed 28hrs, porosity of the cathode increased from 6.8% to 7.9% while that of the anode decreased from 6.5% to 3.5%. When the current-stressing time passed 200hr, porosity of the middle site increased from 8.2% to 17.4%. Meanwhile, changes in the porosity of the cathode and anode were more distinct.

To sum up, electromigration occurred earlier in the current-stressing test and made the porosity change in the cathode and anode. As the current-stressing time extended, the porosity in the middle site became higher, as did the current density. Therefore, the middle site had hot spots and melting was also probable.

Key words: silver nanoparticle paste, hot-pressing technique, pre-existing pores,
electromigration, porosity change of cathode and anode

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