掩膜电镀法制备圆片级封装重布线中孔洞形成机理研究  

Study on the Void Formation in Through-Mask Plated Redistribution Layer in Wafer Level Package

作　　者：宁文果[1,2] 朱春生[1,2] 李珩[1,2] 徐高卫[1] 罗乐[1] 

机构地区：[1]中国科学院上海微系统与信息技术研究所,上海200050 [2]中国科学院大学,北京100049

出　　处：《电子学报》2014年第2期411-416,共6页Acta Electronica Sinica

基　　金：国家科技重大专项(No.2009ZX02025-1)

摘　　要：在圆片级封装电镀铜重布线工艺中通常使用退火的方法促进铜晶粒生长、使电阻减小.而作为电镀铜种子层的溅射铜表面存在的微小裂纹通常会造成电镀液无法进入,从而使电镀铜和溅射铜界面出现孔铜,这类界面缺陷将影响后续高温退火过程中铜晶粒的生长,并导致电镀铜电阻增大.为研究此问题,本文尝试在电镀铜前轻微腐蚀溅射铜种子层,使裂纹尺寸变大,电镀液得以进入裂纹,并电镀填充裂纹形成无孔洞的电镀铜;此外若在电镀铜后在电镀铜表面溅射一层TaN层可限制高温下铜原子运动,使电镀铜经受300℃退火10分钟而不形成孔洞,高温退火同时可使得铜晶粒长大,电阻变小.Thermal annealing is widely used to promote copper grain growth and reduce electrical resistance of the through-mask plated redistribution layer in wafer level package .However ,the crack on the surface of the sputtered copper seed layer prevents the plating process in the crack and increases the electrical resistance ,and results in void formation on the interface between the sputtered seed layer and the plated copper interconnects .To solve this problem ,the sputtered seed layer was slightly etched before the electroplating process and a TaN layer was sputtered on the Cu interconnect surface before thermal annealing process .The pro-cess suppressed void formation during the electroplating process and the annealing process at 300℃ .This process resulted in grain growth at elevated temperature and lower electrical resistance in the copper interconnects .

关 键 词：电镀铜 孔洞 退火 

分 类 号：TN305[电子电信—物理电子学]