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本文针对三维尺寸均处于纳米量级的材料与结构中常见的界面分层破坏问题,利用聚焦离子束技术(FIB)和透射电子显微镜(TEM)开发设计了一套研究纳米材料中界面端部裂纹启裂行为的实验方法.采用FIB成功从宏观多层薄膜材料(硅/铜/氮化硅,Si/Cu/SiN)中切割制备出了由硅基体(Si)和200 nm厚铜薄膜(Cu)及1000 nm厚氮化硅层(SiN)构成的纳米悬臂梁试样.利用高精度微小材料加载装置,在TEM中对该试样进行加载实验,并原位观测了不同试样中Cu/Si界面端部裂纹启裂的行为.通过对启裂瞬时Cu/Si界面上临界应力分布的有限元分析发现,不同尺寸试样中的界面上法向应力与剪切应力均集中在距界面端部100 nm的范围内,且临界法向应力远大于剪切应力.对应力分布的进一步分析则发现,距界面端部5 nm区域内的法向应力场控制着Cu/Si界面的分层破坏过程,可用于表征界面分层破坏的局部控制准则.
In this paper, in order to deal with the delamination of the interfacial interface, which is common in materials and structures with three-dimensional sizes all on the order of nanometers, a series of experiments were carried out to investigate the influence of interface crack at the interface of nanomaterials by focused ion beam (FIB) and transmission electron microscopy (TEM) The experimental method of cracking behavior was successfully prepared by cutting the macroscopically multi-layer thin film material (Si / Cu / Si, Si / Cu / SiN) ) And 1000 nm thick silicon nitride layer (SiN) can be obtained.The loading experiments of the sample in TEM were carried out by using a high precision micro-material loading device and the Cu / Si interface crack initiation behavior.By finite element analysis of the critical stress distribution on the instantaneous Cu / Si interface crack initiation found that the different sizes of sample interface normal stress and shear stress are concentrated in the interface from the end And the critical normal stress is far greater than the shear stress.A further analysis of the stress distribution shows that the normal stress field within 5 nm from the end of the interface controls the delamination of the Cu / Si interface Process, which can be used to characterize the local control of the interface layering damage Guidelines.