Numerical Simulation Of TSV Wafer Backside Thinning Process

With the progress of electronic technology,electronic packaging is developing in the direction of miniaturization,high density and high reliability.The Through Silicon Via(TSV)technology has the advantages of better electrical performance,wider bandwidth,higher density,lower power consumption,smaller size,lighter quality and so on.It is one of the mainstream technologies of high end IC packaging.Although TSV technology has many advantages,semiconductor products based on TSV technology still face many challenges to achieve mass production.TSV wafer is different from bare wafer.The internal structures of TSV-Cu and RDL lead to the complicated internal stress in the grinding process and the obvious stress concentration phenomenon,and then lead to the failure of the TSV wafer in the back grinding process.In order to solve this key problem,the grinding process parameters can be analyzed and optimized by the finite element simulation method to reduce the effect of grinding process parameters on the TSV wafer during grinding process,improve the grinding process reliability and product yield,and then reduce the grinding cost.In this paper,the most commonly used grinding process parameters in wafer grinding process were selected.The ABAQUS finite element analysis software was used to establish the TSV wafer model.Through calculation,the stress of the Si material on the TSV wafer surface was extracted,the stress distribution and the change of the stress were studied.Then the key position stress of the internal structure of TSV wafer was extracted.The stress distribution of TSV and RDL,the movement of stress concentration position,the change of stress value and the stress distribution of RDL in different layers were studied.The single factor analysis was carried out on the feed rate of the grinding wheel,the rotational speed of the grinding wheel,the type of grinding wheel and the elastic modulus of bonding adhesive,the key position stress in the internal structure of TSV wafer was analyzed,then the influence trend and significance of grinding parameters to stress are studied.Through the selection of grinding parameters,the feed rate of grinding wheel,the rotational speed of grinding wheel and the type of grinding wheel are selected as the factors of orthogonal design.The significance of the influence of various grinding parameters on the key position stress of the internal structure of TSV wafer is obtained,and the optimum combination design of various grinding parameters is finally obtained.