利用控制流場的化學銅所開發之接合技術

Abstract

隨著半導體產業的發展，電子產品不斷的朝向體積小、高效能、高接點數發展。隨著尺度的縮小，傳統製程常使用的銲錫接合不再能滿足線寬的要求。為因應更高的接合密度及產品可靠度，銅柱凸塊技術被引入以取代錫球接點，然而銅柱凸塊仍須用到少量銲錫作為接合材料。隨著尺度的不斷縮小，這些微小銲點中的少量銲錫可能會在接合時或經若干時間後完全轉換為缺乏延展性的介金屬化合物，這些接點可能會因在後續加工或使用中遭遇的熱應力及機械應力失效，因此在可靠度上尚有疑慮存在。 對此本研究透過結合微流道以及無電鍍銅，開發一低溫且無須外加壓力的銅對銅接合技術，希望能透過此技術解決目前所遭遇到的問題。 同時本研究對使用此技術時的流場控制進行分析，觀察可能會造成接合不均勻的情形。透過分析的結果提出能避免此現象發生的流場控制方法。最終結果顯示透過有效的流場控制，高均勻的銅柱接合可在低溫且無外加壓力的情況下達成。

With the progress of electronic industries, electronic devices have become smaller, and have better performance. In order to keep this trend, higher I/O number and finer pitch is required for IC packaging. Solder bumps was widely used as a connection technology. However, as the pitch keep shrinking, solder bumps can no longer fit the requirements. To achieve finer pitch, copper pillar bump was chosen as a suitable replacement for solder. But it still has some reliability problems. The solder cap on copper pillars will react with copper and transform into brittle intermetallic material which might fall if there is thermal or mechanical stress. In order to avoid the reliability issues this connection technique is facing. A pressureless and low temperature bonding technology is developed by combining microchannel and electroless copper plating. In this study, we analyze the flow condition in microchannel. Conditions of non-uniform plating is discussed. Finally, a flow control method is developed which can achieve high uniform copper bonding without happening of bridging caused by extraneous deposition.