三维封装电迁移Cu互连线的多物理场模拟仿真  

Multi-physics Simulation of 3D Electromigration of Cu Interconnect

作　　者：张墅野[1] 鲍天宇 修子扬[1] 何鹏[1] ZHANG Shuye;BAO Tianyu;XIU Ziyang;HE Peng(State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology,Harbin 150001,China)

机构地区：[1]哈尔滨工业大学先进焊接与连接国家重点实验室,哈尔滨150001

出　　处：《材料导报》2021年第2期2133-2138,共6页Materials Reports

基　　金：国家重点研发计划项目(2019YFF0217402);国家自然科学基金委青年项目(51805115)。

摘　　要：随着三维封装微互连尺寸向亚微米发展,电流密度大、应力大、散热困难等问题愈发严重,原子尺度迁移失效现象逐渐成为超大规模集成电路不可忽视的可靠性问题。铜比铝的电阻率低,抗电迁移性能更好,是新一代的可靠互连材料,但是对铜互连的原子迁移研究仍有不足。现有的电迁移(Electromigration)可靠性解析化模型主要针对单根金属线恒定温度情形下的电迁移分析,这种方法虽然计算较为简单,但是对现实情况的指导意义较小,主要原因:一是现实情况下高密度集成电路中存在温度梯度,二是互连线的三维结构对互连线的温度以及电流分布有重要影响,而这些参数严重影响着金属原子的抗电迁移性能。本工作提出一种新的电迁移仿真建模方法,通过COMSOL多物理场软件建立了经典三维Cu互连线结构。通过有限元仿真得到三维互连线的温度、电流密度和应力分布,获得了更优的数据仿真结果。结果显示,金属互连线中电流在直角内侧有严重的淤积现象,电迁移在互连线转折处最为剧烈;高温区域位于直角内外侧之间,热迁移的程度随着温度的升高而升高;高应力区域主要是互连线的外边缘处,但是应力迁移在总体电迁移中占比较小,几乎可以忽略。另外,Cu互连线的抗电迁移性能总体优于Ag互连线,是优异的高密度集成电路导体材料。With the development of three-dimensional package interconnects decreasing their sizes into sub-micro levels,problems such as high current density,high-stress,and difficulty heat dissipation have become more and more serious.The phenomenon of atomic-scale migration fai-lure has gradually become a reliability problem that cannot be ignored in VLSI.Copper has a lower resistivity than aluminum and has better electromigration resistance.It is a new generation of reliable interconnect material,but there are still insufficient studies on atomic migration of copper interconnects.The present analytical mode of the electromigration reliability is mainly aimed at the single metal wire at a constant temperature.Although this method is relatively simple to calculate,it has little significance for the guiding of the actual situation.The main reasons are as follows:1.It is the temperature gradient that exists in high-density integrated circuits in reliability.2.The three-dimensional structure of the interconnection line has an important influence on the distribution of the temperature and electrical current of the interconnect.These parameters seriously affect the electromigration resistance of metal atoms.This work proposes a new modeling method of electromigration simulation,and establishes a classic three-dimensional Cu interconnect structure through COMSOL multiphysics software.The temperature,current density and stress distribution by a finite element simulation were carried out and better data simulation results were obtained.The results show that the current in the metal interconnection has serious siltation phenomenon on the inner side of the right angle,and the electromigration is most intense at the turning point of the interconnection line;the high temperature area is located between the inner and outer sides of the right angle,and the degree of thermal migration increases with the increase of temperature;the high-stress area is mainly at the outer edge of the interconnection line,but the stress migration accounts f

关 键 词：电迁移 互连线 原子扩散通量散度 温度影响 材料影响 

分 类 号：TN405.97[电子电信—微电子学与固体电子学]