TCB optimization for stacking large thinned dies with 40 and 20 μm pitch microbumps

In this paper optimization process of D2W (Die to Wafer) TCB (Thermal Compression Bonding) stacking for thinned, warped and large dies are investigated. TCB related characteristics of WLUF (Wafer Level Underfill) is studied in detail by both analytical calculations/simulations and insitu deformation measurement techniques and then the results are used to lower the required bond force of TCB profile. Further optimizations include the enhancement of the interface temperature uniformity, and modification of the top bond tool called Thermode. These optimizations result in good flattening of the thin and warped large die, and uniform pressure distribution during the TCB process. The large stacked dies show very low warpage, very good joint formation between TSVs and 20um pitch microbumps and close to 100{\%} electrical yield.