Thermal characterization of bare-die stacked modules with Cu through-vias

This paper describes the thermal characteristics of three dimensional (3-D) modules where four bare-dies with Cu through-vias are vertically stacked and electrically connected through the Cu-vias and the metal bumps. To realize more accurate thermal analysis for the 3D-modules in the earlier stage of the process development, a series of simple thermal resistance measurements by laser-flash method and parametric numerical analyses have been carried out. First, the thermal effects of the interface between two layers were quantified on the basis of the results of the laser-flash method. Second, using experimental interfacial thermal resistance, the thermal conduction analyses for 3D-modules were carried out. The key parameters governing the thermal performance of bare-die stacked modules and the design guideline of the thermal bumps are presented.