(111)取向纳米孪晶Cu的抗氧化性能及焊料润湿性  

Excellent Oxidation Resistance and Solder Wettability of(111)-Oriented Nanotwinned Cu

作　　者：许增光 周士祺 李晓 刘志权 XU Zengguang;ZHOU Shiqi;LI Xiao;LIU Zhiquan(Shenzhen Institute of Advanced Technology,Chinese Academy of Sciences,Shenzhen 518055,China;Shenzhen College of Advanced Technology,University of Chinese Academy of Sciences,Shenzhen 518055,China;Shenzhen Institute of Advanced Electronic Materials,Shenzhen 518103,China)

机构地区：[1]中国科学院深圳先进技术研究院,深圳518055 [2]中国科学院大学深圳先进技术学院,深圳518055 [3]深圳先进电子材料国际创新研究院,深圳518103

出　　处：《金属学报》2024年第7期957-967,共11页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目No.62274172;广东省基础与应用基础研究基金项目No.2022B1515120037。

摘　　要：在先进封装产业中,(111)取向纳米孪晶Cu ((111)nt-Cu)与一般随机取向多晶组织Cu (C-Cu)相比具有多种优势,包括高强度、出色的延伸率和良好的导电性。近年来,3D封装以及器件小型化的趋势对先进封装中电镀Cu材料理化性能提出了更加严苛的要求,C-Cu直接暴露在空气中容易氧化是先进封装制程中亟待解决的问题,(111)nt-Cu成为代替C-Cu的潜在方案。本工作从Cu基体的氧化层厚度和焊料在Cu基体上的润湿性2个方面,对电镀(111)nt-Cu和C-Cu的抗氧化性能进行了深入分析研究。运用TEM、XPS表征方法,对氧化层成分与厚度进行了测量;采用EBSD和FIB等手段对Cu基体表面的晶界以及晶粒尺寸进行了测量和分析;使用SEM对2种Cu基体/氧化层界面形貌进行了精细表征。结果表明,在250℃空气气氛下,(111)nt-Cu具有比C-Cu更好的抗氧化性能。氧化时间为9 min时,(111)nt-Cu氧化层厚度仅为C-Cu氧化层厚度的43.2%。氧化12 min后,(111)nt-Cu与纯Sn反应制作的焊点的接触角比C-Cu的小26.7%,且焊料铺展面积比C-Cu的大24.6%。2种Cu基体上都生成了含有纳米晶CuO和Cu2O两相混合结构氧化层。(111)nt-Cu具有更好的抗氧化性能,原因是(111)晶面和内部的孪晶界具有更低的表面能,并且其基体表面有更小的大角度晶界面积分数,有效地限制了Cu原子向外的扩散速率。In the advanced-packaging industry,(111)-oriented nanotwinned copper((111)nt-Cu)offers several advantages over common randomly oriented equiaxed polycrystalline Cu(C-Cu),including high strength,excellent elongation,and promising electrical conductivity.In recent years,(111)nt-Cu has shown potential for becoming a C-Cu replacement in under-bump metallization and redistribution layer applications.This shift is attributed to the escalating demand for thermal stability and enhanced electrical and mechanical performances of Cu materials amid the rapid transition toward three-dimensional electronic packaging.This study proposed that(111)nt-Cu exhibits better oxidation resistance than C-Cu after aging in air at 250o C.The thickness and composition of(111)nt-Cu and C-Cu oxide layers were analyzed respectively via TEM and XPS.Various grain boundaries on the surface of the prepared(111)ntCu and C-Cu substrates were evaluated using EBSD and FIB techniques.The morphology at the interface between the two Cu substrates and their oxide layers was characterized using SEM.In addition,the solderability of the oxidized layers was assessed by measuring the wetting angles and spreading areas of the involved Sn-Cu joint structures.Results show that when the oxidation time was 9 min,the thickness of the(111)nt-Cu oxide layer was 43.2%lesser than that of the C-Cu oxide layer.After 12 min of oxidation,the contact angle between Sn and oxidized(111)nt-Cu was 26.7%smaller than that between Sn and oxidized C-Cu,while the spreading area of Sn on(111)nt-Cu was 24.6%larger than that of Sn on C-Cu.After oxidation,the surface layers of both Cu substrates comprised CuO and Cu2O nanocrystals coexisting within the same layer.Because oxidation is closely related to the diffusion of Cu atoms through grain boundaries,the grain boundaries of both Cu substrates were investigated in the natural-growth direction.The results show that compared to C-Cu,(111)nt-Cu has a lower surface energy and smaller area fraction of high angle grain boundaries,effectively

关 键 词：(111)取向纳米孪晶Cu 随机取向多晶Cu 抗氧化性 焊料润湿性 晶界扩散 

分 类 号：TN405[电子电信—微电子学与固体电子学]