A Research on Stress-Induced Deformation of Thin Copper Substrate in Double-Sided Lapping

Abstract

Double-sided lapping is an ultra-precision machining method capable of obtaining high-precision surface. However, during the lapping process of thin pure copper substrate, the workpiece will be warped due to the influence of residual stress-related, including the processing stress and initial residual stress, which will deteriorate the flatness of the workpiece and ultimately affect the performance of components. In this study, finite element method (FEM) was adopted to study the effect of residual stress-related on the deformation of pure copper substrate during double-sided lapping. Considering the initial residual stress of the workpiece, the stress caused by the lapping and their distribution characteristics, a prediction model was proposed for simulating workpiece machining deformation in lapping process by measuring the material removal rate of the upper and lower surfaces of the workpiece under the corresponding parameters. The results showed that the primary cause of the warping deformation of the workpiece in the double-sided lapping is the redistribution of initial residual stress caused by uneven removal of double-sided material. The finite element simulation results were in good agreement with the experimental results.

Numerical analysis of influencing factors on wafer surface flatness in double-sided chemical mechanical polishing process

“…Furthermore, the global flatness of the wafer surface exhibits a tendency to improve firstly and then deteriorate when the planetary wheel's rotational speed increases in relation to the polishing pad [12] . Guo et al [13] noted that an equal amount of material can be removed from the wafer's upper and lower surfaces to effectively release the stress caused by wafer processing and improve the wafer surface's global flatness.…”