Dynamic stress and reliability analysis for bonded wafer during wafer grinding process

摘要

Grinding of bonded wafers is an essential process for fabricating 3D stacked wafer. However, due to the complex structures and various materials of bonded wafers, the risk of cracks in the grinding process of the wafer is greatly increased. In this paper, a dynamic finite element method for grinding of bonded wafer is developed to study the grinding-induced stress. It was found that the heterogeneous structure of the bonded wafer has a large effect on the stress distribution, which is about 17 times higher than the contact pressure between the grinding wheel and the workpiece. The effects of Cu bump diameter/ pitch/ height on stress distribution were also analyzed and discussed.