摘要
超大规模集成电路随着布线层数增加和线宽的缩小,low-k材料的介电常数进一步降低,多孔low-k材料力学性能随之降低,使得晶圆在化学机械抛光(Chemical mechanical polishing,CMP)中面临的主要问题是Cu/Ta/low-k或者超低k材料的界面剥离。针对Si/Cu/Ta/low-k在CMP过程中的承载特性,建立单层布线和多层布线体系的界面力学模型,采用断裂力学理论和有限元法研究Si/Cu/Ta/low-k界面在CMP过程中界面的应力分布规律和界面裂纹的断裂强度。采用能量释放率来描述裂纹的扩展情况,根据界面裂纹能量释放率数值计算方法对裂纹长度、材料性质及不同的布线层数对裂纹扩展时的界面断裂/剥离特性进行仿真分析,得到界面应力分布、能量释放率、相位角与裂纹长度、材料性能、布线层数之间的关系变化曲线。结果表明:随着low-k力学性能降低和布线层数增加,裂纹能量释放率升高,界面裂纹更容易扩展。
With the decreasing feature size and increasing patterned layers of ultra large scale integration,dielectric constant of low-k materials decreases accordingly.Due to poor mechanical strength for porous low-k materials,peeling or delamination of Cu/Ta/low-k or ultra low-k is the key issue for chemical mechanical polishing（CMP）.An interfacial fracture mechanics model is constructed for single-level structure and multi-level structures during CMP.Numerical calculation based on fracture mechanics and finite element method is employed to analyze the stress distribution and interface crack fracture strength in the Si/Cu/Ta/Low-k interface.Crack energy release rate is used to describe expansion of the crack.According to analytic method of crack energy release rate,effects of crack length,material properties and number of patterned layers on the fracture and delamination of interface during the crack expansion are researched.Simulation is made on the influence of crack length,material properties and number of patterned layers on the crack energy release rate,stress distribution and phase angle.The effects of lower modulus,higher initial crack length of low-k materials,and multiple levels of patterned films are found to increase energy release rate.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2012年第4期26-31,39,共7页
Journal of Mechanical Engineering
基金
国家重点基础研究发展计划(973计划
2009CB724201)
清华大学摩擦学国家重点实验室开放基金(SKLTKF09B08)
山西省青年科学基金(2010021023-4)
山西省优秀研究生创新(20093097)资助项目
关键词
能量释放率
界面裂纹扩展
相位角
化学机械抛光
Energy release rate Interface crack expansion Phase angle Chemical mechanical polishing
