覆晶組裝打線金凸塊與鋁墊之界面介金屬反應研究

Abstract

本研究主要觀察覆晶組裝中，打線金凸塊與鋁墊之界面反應。熱超音波接合為超音波接合與熱壓接合的混合技術，在接合的製程中基板維持在150~250℃，此接合溫度會影接合界面的介金屬化合物成長，特別是直接在12吋矽晶圓上植球。另外在一片環保的聲浪中，無鉛製程大受歡迎，不過此製程需要較高的製程溫度，也提高了介金屬造成失效的可能。在本實驗中我們將金凸塊覆晶接合的過程分成兩個部分研究，第一部份為單純的Au/Au接合；第二部份為Au/Al接合。 研究結果顯示在不同溫度時效時，金金覆晶接點皆破斷在金球內部，強度不隨時效時間而有重大的改變。金鋁覆晶接點則有不同的破斷模式，如Cratering、破斷在金球內部或斷裂在介金屬中，皆為影響強度的重要因素。低溫時效的破斷主要是因Cratering現象所致，高溫失效則因伴隨介金屬成長而出現的Kirkendall voids所造成。本實驗利用穿透式電子顯微鏡、掃描式電子顯微鏡、光學顯微鏡和歐傑電子能譜儀，探討金鋁介金屬成長的機制、成分及對接點強度的影響。

The effort of this study is to comprehend the interfacial reaction of gold bump and aluminum pad. Thermosonic bonding combines the ultrasonic bonding and thermo-compression bonding. In the process of bonding, substrates maintain 150~250℃. This bonding temperature affects the growth of IMC, especially when the bonding lasts longer. Furthermore, Pb-free technology needs higher process temperatures which may cause joints failure. In this study, we will investigate Au/Au joints and Au/Al joints. According to this study, Au/Au joints all break in the gold solder and their strength doesn’t change with time. However, there are different sorts of failure modes in Au/Al joints. These failure modes affect the ball shear strength. Au/Al joints break in the lower temperature due to the cratering effect and break in the higher temperature due to the Kirkendall voids. In this research, we use TEM , SEM , OM and AES to investigate intermetallic compound .