Zhu Liang, Mei Biao, Zhu Weidong, Li Wei
School of Mechanical Engineering, Zhejiang University, Hangzhou 310027, China.
Quanzhou Institute of Equipment manufacturing, Haixi Institutes, Chinese Academy of Sciences, Quanzhou 362216, China.
Sensors (Basel). 2020 Mar 13;20(6):1603. doi: 10.3390/s20061603.
Thickness control is a critical process of automated polishing of large and thin Si wafers in the semiconductor industry. In this paper, an elaborate double-side polishing (DSP) system is demonstrated, which has a polishing unit with feedback control of wafer thickness based on the scan data of a laser probe. Firstly, the mechanical structure, as well as the signal transmission and control of the DSP system, are discussed, in which the thickness feedback control is emphasized. Then, the precise positioning of the laser probe is explored to obtain the continuous and valid scan data of the wafer thickness. After that, a B-spline model is applied for the characterization of the wafer thickness function to provide the thickness control system with credible thickness deviation information. Finally, experiments of wafer-thickness evaluation and control are conducted on the presented DSP system. With the advisable number of control points in B-spline fitting, the thickness variation can be effectively controlled in wafer polishing with the DSP system, according to the experimental results of curve fitting and the statistical analysis of the experimental data.
厚度控制是半导体行业中大尺寸薄硅片自动抛光的关键工艺。本文展示了一种精心设计的双面抛光（DSP）系统，该系统具有一个抛光单元，可基于激光探头的扫描数据对晶圆厚度进行反馈控制。首先，讨论了DSP系统的机械结构以及信号传输与控制，其中重点强调了厚度反馈控制。然后，探索激光探头的精确定位，以获取晶圆厚度的连续有效扫描数据。之后，应用B样条模型对晶圆厚度函数进行表征，为厚度控制系统提供可靠的厚度偏差信息。最后，在提出的DSP系统上进行了晶圆厚度评估与控制实验。根据曲线拟合的实验结果和实验数据的统计分析，通过在B样条拟合中设置合适数量的控制点，利用DSP系统可在晶圆抛光过程中有效控制厚度变化。
