面向IC新封装技术的超薄晶圆磨削机理及技术基础

To meet the demand of new packaging technology for ultra-thin wafer in IC manufacturing, the foundation theroy and key technologies of the back grinding of wafer with outer rim (BGWOR) are systematically researched according to the characteristic of BGWOR processing. Based on the geometrical characteristic, mechanical parameters and contact behaviors testing at the micro-scale, the law of interaction among the diamond wheel, ultra-thin wafer and flexible tape in BGWOR is researched and the theoretical model is established; considering the geometric and kinematic relationship between wheel and wafer, the formation mechanism of wafer surface and the law of wafer deformation are studied, and the model of wafer bending and warping is established; the model of subsurface damage of wafer is established by researching the mechanism and control method of surface and subsurface damage; the ultra-thin wafer is processed by force/position control and grinding/polishing method; based on the analysis of test and grinding experiment, the law of wafer ultra-precision thinning process is put forward. In this project, the mechanism of material removal and surface formation, the law of interaction between wafer surface quality and profile accuracy in wafer thinning process are revealed, and the ultra-thin wafer processing with high-efficiency, high-precision and low damage is proposed. This project, as a front-project in related area which has both specific applied background and has the important academic value, will provide advanced theory and technology in wafer ultra-thinning for China's IC manufacturing.

面向IC新封装技术对超薄晶圆的需求，针对留边磨削减薄工艺的特点和问题，系统研究留边磨削减薄加工的基础理论和关键技术。通过微观尺度下的几何特征、力学参数和接触行为测试，研究留边磨削减薄时的金刚石砂轮、超薄晶圆和柔性蓝膜三者间的相互作用规律并建立其理论模型；通过砂轮与晶圆相互作用的几何运动关系，研究晶圆表面形成机理及其变形规律，建立晶圆弯曲或翘曲变形模型；研究晶圆表面/亚表面损伤机理及其控制方法，建立晶圆亚表面损伤模型；开发基于力-位控制和磨抛组合方法的晶圆超薄加工工艺；通过测试分析和加工试验，研究晶圆超精密减薄加工工艺规律。通过本项目的研究，揭示晶圆减薄加工时材料去除和表面形成机理、晶圆表面质量和面型精度的影响规律，提出超薄晶圆的高效率高精度低损伤加工工艺。本项目是相关领域的前沿性研究课题，既有明确的应用背景，又有重要的学术价值，将为我国IC制造提供先进的晶圆超薄化加工理论与技术。

面向 IC 新封装技术对超薄晶圆的需求，针对留边磨削减薄工艺的特点和问题，系统研究了留边磨削减薄加工的基础理论和关键技术。建立了柔性蓝膜、超薄晶圆和金刚石砂轮间的相互作用理论模型，建立了薄晶圆变形有限元分析模型，研究了晶圆在超精密磨削过程中晶圆的亚表面损伤分布规律，揭示了晶圆在超精密磨削减薄过程中的变形规律，得出了晶圆磨削减薄变形与亚表面损伤层厚度、晶圆减薄厚度、亚表面损伤层内的加工应力以及硅晶圆自身力学特性之间的数学关系，晶圆磨削减薄变形随着内部加工应力和亚表面损伤层厚度的增大而增大、晶圆减薄厚度的增大而减小；确定了磨削减薄工艺参数对晶圆面型精度和晶圆变形的控制方法。通过本项目的研究，揭示了晶圆磨削减薄加工时表面形成机理和材料去除、晶圆面型精度和晶圆表面质量的影响规律，在无光磨条件下磨削晶圆的亚表面损伤深度沿整个晶圆表面分布不均匀，沿圆周方向在<100>晶向的亚表面损伤深度小于<110>晶向，沿半径方向，从晶圆中心到边缘的亚表面损伤深度逐渐增大，砂轮粒度越大，亚表面损伤深度沿晶向和径向的变化越明显，提出了磨削超薄晶圆的磨抛组合工艺和磨削过程力-位控制，确定了晶圆一次装夹定位条件下，依次采用#600金刚石砂轮粗磨削、#3000金刚石砂轮精磨削和#3000 MgO软磨料砂轮机械化学低损伤磨削的晶圆高效低损伤磨削减薄工艺，最终磨削减薄厚度为40μm。本项目的研究成果为我国 IC 制造提供了先进的晶圆超薄化加工理论与技术。