Jeong Seonho, Shin Yeongil, Jeong Jongmin, Jeong Seunghun, Jeong Haedo
Graduated School of Mechanical Engineering, Pusan National University, Busan 46703, Republic of Korea.
Materials (Basel). 2024 Apr 15;17(8):1817. doi: 10.3390/ma17081817.
Chemical mechanical planarization (CMP) reduces film thickness, eliminates step height, and achieves high levels of planarity in semiconductor manufacturing. However, research into its mechanisms is still in progress, and there are many issues to be resolved. To solve problems in CMP, it is necessary to understand the contact phenomenon that occurs at the pad-wafer interface, especially pad asperity. Moreover, understanding the non-uniform distribution of pad asperity, such as height and radius, is essential for predicting the material removal rate (MRR). In this study, based on the existing Greenwood-Williamson (GW) theory and probability density function (PDF), a modified mathematical model that includes changes in asperity distribution was developed and validated experimentally. The contact model proposed in this study included functions that calculated the time-dependent height and radius wear of the pad asperities. Specifically, the experimentally obtained values were compared with the values obtained by the model, and the comparison results were analyzed. Thereby, it was found that the contact model and MRR model considering the change in asperity wear and distribution due to CMP proposed in this study are in better agreement with the experimental results than the existing model, which shows that the MRR can be predicted by a mathematical model using the change in asperity distribution.
化学机械平面化（CMP）可降低膜厚、消除台阶高度，并在半导体制造中实现高水平的平面度。然而，对其机理的研究仍在进行中，还有许多问题有待解决。为了解决CMP中的问题，有必要了解在抛光垫 - 晶圆界面处发生的接触现象，尤其是抛光垫粗糙度。此外，了解抛光垫粗糙度的不均匀分布，如高度和半径，对于预测材料去除率（MRR）至关重要。在本研究中，基于现有的格林伍德 - 威廉姆森（GW）理论和概率密度函数（PDF），开发了一个包含粗糙度分布变化的改进数学模型，并通过实验进行了验证。本研究提出的接触模型包括计算抛光垫粗糙度随时间变化的高度和半径磨损的函数。具体而言，将实验获得的值与模型获得的值进行比较，并对比较结果进行分析。由此发现，本研究提出的考虑CMP引起的粗糙度磨损和分布变化的接触模型和MRR模型与实验结果的一致性比现有模型更好，这表明可以通过使用粗糙度分布变化的数学模型来预测MRR。
