基于微观结构的Cu互连电迁移失效研究  

A microstructure-based study on electromigration in Cu interconnects

作　　者：吴振宇[1] 杨银堂[1] 柴常春[1] 刘莉[1] 彭杰[1] 魏经天[1] 

机构地区：[1]西安电子科技大学微电子学院,宽禁带半导体材料与器件教育部重点实验室,西安710071

出　　处：《物理学报》2012年第1期493-498,共6页Acta Physica Sinica

基　　金：国家自然科学基金青年科学基金(批准号:60806034)资助的课题~~

摘　　要：提出了一种基于微观晶粒尺寸分布的Cu互连电迁移失效寿命模型.结合透射电子显微镜和统计失效分析技术。研究了Cu互连电迁移失效尺寸缩小和临界长度效应及其物理机制.研究表明,当互连线宽度减小,其平均晶粒尺寸下降并导致互连电迁移寿命降低.小于临界长度的互连线无法提供足够的空位使得铜晶粒耗尽而发生失效.当互连长度大于该临界长度时,在整个电迁移测试时间内,部分体积较小的阴极端铜晶粒出现耗尽情况.随着互连长度的增加该失效比例迅速增大,电迁移失效寿命减小.当互连长度远大于扩散长度时,失效时间主要取决于铜晶粒的尺寸,且失效寿命和比例随晶粒尺寸变化呈现饱和的波动状态.A microstructure-based electromigration model of Cu interconnects is proposed.Mechanisms of scaling and critical length effects of Cu electromigration are studied by transmission electron microscopy and statistical failure analysis.The results show that the lifetime of electromigration is reduced with Cu grain size decreasing when the width of interconnect is scaled down.Electromigration failure is not observed when the interconnect length is smaller than the critical length due to insufficient vacancies for voiding the whole Cu grains.Some small grains are vacated at the cathode end when the interconnect length is larger than the critical length during the testing. The proportion of failures increases and the lifetime decreases with interconnect length increasing.The failure time is dependent mainly on Cu grain size,and the failure lifetime and failure proportion fluctuate with grain size varying when the interconnect length is beyond the diffusion length.

关 键 词：CU互连 电迁移 微观结构 

分 类 号：TN405[电子电信—微电子学与固体电子学]