Zhao Bingyao, Huang Ning, Dai Siyang, Zhou Ping
State Key Laboratory of High-Performance Precision Manufacturing, Department of Mechanical Engineering, Dalian University of Technology, Dalian 116024, China.
Materials (Basel). 2024 Aug 3;17(15):3852. doi: 10.3390/ma17153852.
Crack generation and propagation are critical aspects of grinding processes for hard and brittle materials. Despite extensive research, the impact of residual cracks from coarse grinding on the cracks generated during fine grinding remains unexplored. This study aims to bridge this gap by examining the propagation law of existing cracks under indentation using the extended finite element method. The results reveal that prefabricated cracks with depths less than the crack depth produced on an undamaged surface tend to extend further without surpassing the latter. Conversely, deeper prefabricated cracks do not exhibit significant expansion. A novel method combining indentation and prefabricated cracks with fracture strength tests is proposed to determine crack propagation. Silicon wafers with varying damaged surfaces are analyzed, and changes in fracture strength, measured by the ball-on-ring method, are utilized to determine crack propagation. The experimental results confirm the proposed crack evolution law, validated by damage assessments across different grinding processes, which is suitable for crack damage. The findings demonstrate that residual cracks from coarse grinding are negligible in predicting the maximum crack depth during fine grinding. This research provides a crucial foundation for optimizing the wafer thinning process in 3D stacked chip manufacturing, establishing that changes in fracture strength are a reliable indicator of crack propagation feasibility.
裂纹的产生和扩展是硬脆材料磨削过程中的关键环节。尽管已有大量研究，但粗磨产生的残余裂纹对细磨过程中产生的裂纹的影响仍未得到探索。本研究旨在通过使用扩展有限元方法研究压痕作用下现有裂纹的扩展规律来填补这一空白。结果表明，深度小于未损伤表面产生的裂纹深度的预制裂纹倾向于进一步扩展，但不会超过后者。相反，更深的预制裂纹没有显著扩展。提出了一种将压痕、预制裂纹与断裂强度测试相结合的新方法来确定裂纹扩展。对具有不同损伤表面的硅片进行了分析，并利用通过环上滚珠法测量的断裂强度变化来确定裂纹扩展。实验结果证实了所提出的裂纹扩展规律，该规律通过对不同磨削过程的损伤评估得到验证，适用于裂纹损伤。研究结果表明，在预测细磨过程中的最大裂纹深度时，粗磨产生的残余裂纹可以忽略不计。本研究为优化三维堆叠芯片制造中的晶圆减薄工艺提供了关键基础，确定了断裂强度的变化是裂纹扩展可行性的可靠指标。
