Cu-Sn 冶金反應通道之生成研究

Abstract

隨著電子產業的發展，電子產品紛紛追求高效能、體積小的趨勢發展，三維積體電路技術因應而生，其中微凸塊接點被用來連接上下層的矽晶片，因為微凸塊的銲錫高度小於20 微米，在迴銲時會使銲錫形成介金屬化合物且佔據大部分，而晶片與晶片之間以銅錫材料的微凸塊作接點比鎳錫有更好的潤濕性，因此銅錫的冶金反應在封裝上會顯得相當重要。在文獻中，雙層銅錫與三層銅錫銅，經過冶金反應會形成Cu6Sn5 與Cu3Sn 的介金屬化合物，在介金屬層中發現有通道的存在，通道形成可以提供原子擴散的通路導致銅原子可以藉由通道擴散至液態銲錫裡並使晶粒成長。本實驗為了發現通道生成的臨界銲錫高度和迴銲溫度，使用銲錫高度 10/30/60 微米和迴銲溫度 260/ 300/340 度觀察冶金反應下介金屬生成形貌和原子擴散行徑。

As the blooming of electronic industry, the micrometer scale technology with higher efficiency components has become a better solution to fulfil the upcoming innovative electronic products. Microbumps are adapted as the interconnect between chips in 3D integrated circuit packaging. In the scale of microbumps which with the solder height below 20um, the product of solder reflow as know as inter metallic compound (IMC) becomes relatively crucial. In connection, microbumps made of copper-tin are typically used as joints between chips because copper-tin is better than copper-nickel in terms of wetting. This leads to the importance of copper-tin metallurgical reaction in the field of package assembly. It was reported that double layer Cu/Sn and triple layer Cu/Sn/Cu will produce the IMC of Cu6Sn5 and Cu3Sn respectively after metallurgical reaction. The channels form within IMC layer provide a diffusion path for copper molecules penetrating to molten solder and activating the kinetic growth of inter metallic compounds in microbumps. In this study, we aim to reveal the threshold value of bump height and reflow temperature for the formation of channels by selecting 10/30/60 um as bump heights and 260/300/340℃ as reflow temperatures. The results show that no channels was found in 10-um-high solder joints. However, channels were observed in 30 um and 60 um high solder joints.