Finite element analysis of deflection and residual stress on machined ultra-thin silicon wafers
Finite element analysis of deflection and residual stress on machined ultra-thin silicon wafers
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DOI：
10.1088/0268-1242/26/10/105002
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发表时间：
2011-10-12
影响因子：
1.9
通讯作者：
Shimizu, J.
中科院分区：
文献类型：
--
作者：
Tian, Y. B.;Zhou, L.;Shimizu, J.
近年来，随着小型化电子设备的快速发展，对超薄硅片的需求不断升级。减薄过程中产生的残余应力对超薄晶圆的加工质量影响很大。这项工作开发了一个二维轴对称有限元（FE）模型来预测研磨超薄晶圆的偏转和全场残余应力。有限元模型由两层结构组成，即减薄过程引起的损伤层和无缺陷的体硅晶体层。对损伤层施加一系列均匀的面内应变，以模拟加工产生的初始应力。在初始应力释放后，使用开发的有限元模型预测加工超薄晶圆中的全场残余应力分布。基于有限元模型，揭示了晶片几何尺寸和加载初始应变（或应力）对最大压缩/拉伸残余应力和最大晶片偏转的影响。最后通过将模拟的晶圆偏转与测量值进行比较来验证模型。基于这项工作，可以方便地预测加工后的超薄晶圆的挠度和残余应力。
The demand for ultra-thin silicon wafers has escalated in recent years with the rapid development of miniaturized electronic devices. Residual stress generated in the thinning process has a great influence on the machining quality of ultra-thin wafers. This work has developed a 2D axisymmetric finite element (FE) model to predict the deflection and full-field residual stress of ground ultra-thin wafers. The FE model consists of two-layer structures, i.e. a damage layer induced by the thinning process and a bulk silicon crystal layer without defects. A series of uniform in-plane strains is applied to the damage layer to simulate machining-generated initial stress. A full-field residual stress distribution in a machined ultra-thin wafer is predicted with the developed FE model after the initial stress is released. Based on the FE model, effects of wafer geometrical dimensions and loaded initial strain (or stress) on the maximum compressive/tensile residual stress and the maximum wafer deflection are revealed. The model is finally verified by comparing the simulated wafer deflection with the measured value. Based on this work, the deflection and residual stress of a machined ultra-thin wafer can be conveniently predicted.