利用连续电镀工艺在C194铜片上制备了W含量为33.21%的晶态NiW(c?NiW)合金阻挡层,随后镀纯锡.采用扫描电镜(SEM)、背散射电子成像(BSE)、能谱(EDS)等手段研究了c?NiW合金阻挡层在回流及高温老化试验(HTST)中的界面演变.观察到c?NiW合金阻挡层的界面出现了由Ni、W和Sn组成的新相"亮层".通过跟踪原子扩散路径以及相图推算,认为"亮层"是以Ni4W为基体、Sn固溶扩散的三元合金相.Ni4W原本就存在于c?NiW合金阻挡层中,由于回流以及高温老化过程中Ni不断消耗以及Sn的逐渐扩散,"亮层"开始逐渐形成并显现.推测了Cu/NiW/Sn微凸点界面演变的过程.%C194 copper strip was continuously electroplated with a crystalline NiW (c-NiW) alloy barrier layer containing 33.21% tungsten, and then subjected to pure tin electroplating. The interface transition ofc-NiW alloy during reflow and high- temperature storage test (HTST) was studied by scanning electron microscopy (SEM), backscattered electron imaging (BSE) and energy-dispersive X-ray spectroscopy (EDS). A new phase called "bright layer" consisting of Ni, W and Sn was observed during the reflow and HTST at the interface ofc-NiW alloy barrier layer. Through atom diffusion tracking and phase diagram deducing, the bright layer was considered to be a ternary alloy phase based on Ni4W with solid solution of Sn. The Ni4W exists originally in the as-electroplatedc-NiW alloy barrier layer. With the consumption of Ni and the diffusion of Sn during the reflow and HTST processes, the bright layer starts to appear. The interface transition of Cu/NiW/Sn in copper pillar bumping was concluded.
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