Finite Element Analysis of the upscaling of Warpage and Bifurcation Hysteresis Loops: from Cu/Si Die to Large Wafers

Abstract:
Large semiconductor wafers with thick electrochemical deposited copper (Cu_ECD) layers suffer from severe warpage during the final thinning process. This can lead to an asymmetric warpage or bifurcation of the wafer. Finite element analysis software can predict the phenomenon of warpage and bifurcation, but an accurate prediction requires considering the plastic behavior of the metal layer. The study investigated the extension of a finite element analysis multilinear kinematic hardening model of plastic Cu_ECD from a die level to the wafer level to predict the warpage hysteresis loop and deduce the phenomenon of bifurcation during the thinning process of a 200 mm standard wafer.