高温高应变下Cu/Ta界面扩散行为的分子动力学模拟  

Molecular dynamics simulation of Cu/Ta interface diffusion behavior under high temperature and high strain

作　　者：张磊洋 肖雯天 柳和生 李刚龙 ZHANG Leiyang;XIAO Wentian;LIU Hesheng;LI Gangong(School of Mechanical and Electronic Engineering,East China University of Technology,Nanchang330013,China;School of Mechanical and Electronic Engineering,East China Jiaotong University,Nanchang330013,China)

机构地区：[1]东华理工大学机械与电子工程学院,江西南昌330013 [2]华东交通大学机械与电子工程学院,江西南昌330013

出　　处：《电子元件与材料》2024年第10期1274-1283,共10页Electronic Components And Materials

基　　金：江西省教育厅科学技术研究项目(GJJ2200725);东华理工大学博士启动基金(DHBK2019161)。

摘　　要：采用铜互连的三维集成技术是提高微电子器件性能的一种很有前景的方法。然而,由于铜易扩散到硅电子器件中,导致其性能降低甚至失效,而钽(Ta)凭借稳定的化学性能常被作为阻挡层应用在工程中。为探究Cu/Ta体系的扩散行为,采用分子动力学方法,分别研究了温度和应变耦合作用下对Cu/Ta体系扩散的影响,通过对单晶结构和多晶结构的分析,厘清了两者扩散机理。在温度作用下,经过10ns的保温,仅出现了Ta原子向Cu原子内部扩散的现象,并且Ta原子向多晶Cu扩散的深度更深,达到1.5nm。在应变作用下,体系中产生大量的晶体缺陷,多晶Cu内部出现的位错缠结、孪晶和晶界破裂加剧了扩散。随着应变的不断增加,Ta中位错密度增加,使Cu原子向Ta晶格内部扩散,扩散层厚度达到3.3nm。分子动力学模拟结果表明,Ta在温度作用下是一种非常有效的阻挡层,但在应变作用下其阻挡性能会逐渐消失,不再具备阻挡能力。Three-dimensional integration technology of using copper interconnects is an effective approach to enhance the performance of microelectronic devices.However,the diffusion of copper atoms into silicon can significantly degrade their performance of the electronic devices,which even can cause failure.Chemically stable tantalum(Ta)is often employed as a barrier layer to enhance reliability of the electronic devices.To study the diffusion behavior of at the Cu/Ta interface,molecular dynamics simulations were carried out to investigate the effects of temperature and strain coupling.The diffusion mechanism at the Cu/Ta interface was analyzed in both single-crystalline and polycrystalline structures.At elevated temperatures,Ta atoms can penetrate into the Cu crystal lattice after 10ns of annealing,where the penetration depth is greater for polycrystalline Cu and can reach up to 1.5nm.Upon strain application,multiple defects were generated in the polycrystalline Cu,including dislocation tangles,twinning,and grain boundary ruptures,which leads to increase of dislocation density in Ta and thicker diffusion layer of 3.3nm.The molecular dynamics simulation results shows that Ta is a highly effective barrier layer under high temperature conditions.However,its resistance of Cu diffusion gradually decreases and even disappear under strain.This study provides valuable insights into the reliability of Ta as a diffusion barrier in Cu interconnects,contributing to the development of more robust microelectronic devices.

关 键 词：分子动力学 界面扩散 阻挡层 拉伸 CU互连 Cu/Ta 

分 类 号：TN406[电子电信—微电子学与固体电子学]