隨著科技的進步，構裝方式由3-D IC構裝取代傳統2-D構裝技術成為未來趨勢。覆晶為3-D IC構裝中其中一種接合方式。近年來常使用銅柱凸塊取代錫鉛凸塊，利用銅柱和少量的銲料進行接合，避免傳統銲料接合時彼此橋接的現象，減少銲料彼此間距達到腳距密集化(fine pitch)效果。本實驗利用電鍍技術製作Cu pillar/Sn和In/Ni/Cu多層結構，利用Sn-In當作連接層進行固-液擴散接合可有效降低焊接溫度，希望接合後之Cu pillar/Sn/In/Ni/Cu多層結構夠取代傳統銲錫並運用於3-D IC構裝中。
研究結果顯示此兩種溫度系統下，其靠近銅柱端界面處皆會生成(Cu,Ni)6(Sn,In)5相，中間粗糙層為相。在180oC系統經過迴焊之界面生成相由銅柱端至鎳端依序為Cu pillar/(Cu,Ni)6(Sn,In)5/相/Ni。經過10小時時效靠近鎳端有(Cu,Ni)6(Sn,In)5與(Cu,Ni)(In,Sn)2相生成，隨著時間增加生成的介金屬相並不會有任何改變，而相面積有逐漸減小的趨勢。於迴焊溫度200oC下，其界面生成相由銅柱端至鎳端依序為Cu pillar/(Cu,Ni)6(Sn,In)5/相/(Cu,Ni)6(Sn,In)5/Ni。可以觀察到靠近鎳端之(Cu,Ni)6(Sn,In)5生長較180oC系統來的迅速，隨著時效時間的增加靠近鎳端有(Cu,Ni)(In,Sn)2相生成，且中間之相已經完全消耗殆盡。當時效時間至300小時，此時界面的生成相依序為Cu pillar/(Cu,Ni)6(Sn,In)5/(Cu,Ni)(In,Sn)2/Ni，相較於剛開始接合之界面有明顯的變化。

With the development of technology, the 3-D IC packaging tends to replace the traditional 2-D packaging technology in the future. Flip chip (FC) technique is one of the methods in 3-D IC packaging. Recently, the copper pillar bump was used to replace tin-lead bumps for the reason that it could provide fine pitch without bump bridging and smaller amount of solder is needed.
In this study, the Cu pillar/Sn and In/Ni/Cu multilayer structure were fabricated by the electroplating method. In the solid-liquid inter-diffusion (SLID) bonding process, Sn-In was used as a bonding layer to effectively reduce the soldering temperature. We hope this Cu pillar/Sn/In/Ni/Cu multilayer structure could act as the solder to replace conventional lead-free solder and be applied in 3-D IC packaging.
The results indicate (Cu,Ni)6(Sn,In)5 phase were formed on the Cu pillar side in different temperature systems and the rough layer, which can be found in the middle, was  phase. When the reflowing temperature was 180 oC, the intermetallic compounds (IMCs) formed from Cu pillar side to Ni side were Cu pillar/(Cu,Ni)6(Sn,In)5 // Ni. After aging for 10 h, the (Cu,Ni)6(Sn,In)5 and (Cu,Ni)(In,Sn)2 phases were formed at interface close to the Ni side. In addition, the IMCs didn’t change and the area of  phase was reduced when we increase aging time. In the other system, couple was reflowed at 200oC, the IMCs formed from Cu pillar side to Ni side were Cu pillar/(Cu,Ni)6(Sn,In)5/(Cu,Ni)6(Sn,In)5/Ni. The (Cu,Ni)6(Sn,In)5 phase was formed more rapidly than 180 oC system on the Ni side. With longer aging time, the (Cu,Ni)(In,Sn)2 was formed at the interface close to the Ni side and the phase was consumed completely. When aging for 300 h, the IMCs formed from Cu pillar side to Ni side were Cu pillar/ (Cu,Ni)6(Sn,In)5/ (Cu,Ni)(In,Sn)2/Ni, which was significantly different compared to the as-reflowed.

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