铜互连兆声清洗中结构损伤预测的有限元分析  

Finite element analysis of structure failure in Cu interconnect megasonic cleaning

作　　者：黄雅婷[1] 孟春玲[1] 董秀萍[1] 路新春[2] 

机构地区：[1]北京工商大学材料与机械工程学院,北京100048 [2]清华大学摩擦学国家重点实验室,北京100084

出　　处：《光学精密工程》2013年第8期2064-2070,共7页Optics and Precision Engineering

基　　金：国家自然科学基金青年基金资助项目(No.51205006);清华大学摩擦学国家重点实验室开放基金资助项目(No.SKLTKF11A01);北京市委组织部优秀人才计划资助项目(No.2011D005003000006);北京市教委重点资助项目(No.KZ201210011012)

摘　　要：尽管用于铜及低介电材料(low-k材料)互联加工的兆声清洗工艺可以提高纳米颗粒的去除率,但清洗过程中的声波能量会破坏微小器件结构从而导致器件功能失效。本文采用有限元分析法分析和预测了兆声波的破坏作用,研究了铜及low-k材料互联结构在兆声清洗过程中的应力分布及变形。基于ABAQUS软件,采用二维有限元模型对循环布线图形当中的一个典型元胞在空化气泡破裂冲击下的应力应变进行分析,并讨论了它的破坏形式和破坏规律。结果表明,最大应力集中在铜及low-k材料键合处将导致low-k材料分层。当线宽为22nm时,应力和结构变形达最大值,分别为1 379MPa和3.074nm;之后随线宽增加最大应力应变值均减小。另外,兆声频率增大不改变应力应变分布规律,对应力应变极值影响亦不明显。分析及预测结果与工业实践得到的结果相符。Although megasonic cleaning can remove effectively nano particles in the Cu/low-k intercon- nection post-Chemical Mechanic Polishing （post-CMP） cleaning, the megasonic energy in cleaning may also cause extensive damage to microstructures. To predict the damage, the structural deforma- tion and the stress distribution of Cu and low-k materials in megasonic cleaning were examined with Finite Element Analysis（FEA）. Two-dimensional models were used in analysis of the stress-strain of a typical cell impacted by a caviation bubble in the circulate wiring pattern and all of the simulations were performed with ABAQUS. The results show that the maximum stress is concentrated in the binding area between Cu and low-k, which will result in the delamination of low-k materials. When the line width is 22 nm, the stress and deformation reach the largest values by 1 379 MPa and 3. 074 nm respectively. When the line width is more than 22 nm, the max stress and max deformation de- crease with increase of Cu line width. The increasing frequency will not change the stress distribution and displacement. The results are in agreement with the defect found in industrial applications.

关 键 词：化学机械抛光 兆声清洗 铜互联 有限元分析 

分 类 号：TN305[电子电信—物理电子学]