Development an identification method of friction coefficient between wafer and carrier in double-sided lapping
Development an identification method of friction coefficient between wafer and carrier in double-sided lapping
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DOI：
10.1016/j.precisioneng.2019.01.005
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发表时间：
2019-03-01
影响因子：
3.6
通讯作者：
Hosokawa, Akira
中科院分区：
文献类型：
--
作者：
Hashimoto, Yohei;Sano, Tomoya;Hosokawa, Akira
在双面研磨中，晶片的行为是最重要的问题之一，因为它取决于材料去除率的分布。尽管晶片与载体之间的摩擦系数会影响晶片的行为，但这个系数几乎没有被讨论过。为了准确估计硅片在双面研磨机上的单面研磨过程中的摩擦系数，提出了一种基于单面研磨时硅片转速随载体位置变化的摩擦系数辨识方法。摩擦系数是通过比较晶片转速的实验变化和理论变化来确定的。实验是在硅片与载体之间的润滑条件类似于双面研磨的情况下进行的，并通过对硅片行为的图像处理来测量这种变化。理论变化是基于施加在晶片上的力和力矩的平衡来计算的。结果表明，在一定的摩擦系数条件下，硅片的最高转速、最低转速以及随载流子中晶片位置的变化均与实测值吻合较好。因此，假定实际系数是利用该方法进行识别的。此外，利用识别的摩擦系数计算了硅片在双面研磨中的行为，并建议精确考虑晶片与载体之间的接触状态，即无滑移、滑移和非接触对于实际估计是必不可少的。
Behavior of a wafer is one of the most significant concerns in double-sided lapping since it depends on the distribution of material removal rate. Though the wafer behavior is affected by the friction coefficient between the wafer and a carrier, the coefficient has hardly been discussed. In this study, an identification method of the friction coefficient based on variation of wafer rotational speed with wafer position in the carrier during single-sided lapping operation on double-sided lapping machine is developed for accurate estimation of the wafer behavior. The friction coefficient is identified by comparing experimental and theoretical variation of the rotational speed of the wafer. The experiment is carried out under the condition where lubrication condition between the wafer and the carrier is similar to that in double-sided lapping, and the variation is measured by image processing of the wafer behavior. The theoretical variation is calculated based on the equilibrium of force and moment applied to the wafer. It is confirmed that the theoretical rotational speed of the wafer under a friction coefficient condition agrees well with the measured one in terms of not only the highest and the lowest speed but also the variation with the wafer position in the carrier. Thus, it is assumed that the practical coefficient is identified by utilizing this method. In addition, the behavior of the wafer in double-sided lapping is calculated using the identified friction coefficient, and it is suggested that precise consideration of the contact status between the wafer and the carrier, i.e., non-slip, slip, and non-contact is essential for practical estimation.