Process integration of fine pitch micro-bumping and Cu redistribution wiring for power efficient SiP

Leading-edge LSI products with 40nm logic technology node and beyond are facing the issue of how higher memory bandwidth is reconciled with lower power consumption. Chip stacking of a logic chip on a large-scale DRAM chip, interconnected with each other by fine-pitch bumps, provides a solution to realize a power efficient SiP (System in Package). In this paper, the successful process integration of 10µm pitch Cu redistribution wiring and 40µm pitch SnCu micro-bumping on 300mm wafers, together with chip-on-chip (CoC) joining, has been described in an effort to relinquish embedded DRAM (eDRAM) SoC (System on Chip).