Challenges of design and packaging for 3D stacking with logic and DRAM dies

Abstract

A Wide IO DRAM controller chip with Through Silicon Via (TSV) technology is implemented. Test circuitry for prebonding TSV tests are embedded in between the fine pitch TSVs. In order to reduce Vmin degradation induced by 512 DQs simultaneously switching noise, we introduce a package-board impedance optimization method utilizing a full digital noise monitor. We also develop a 3D stacked flip chip assembly process with void less underfill enabled by Non Conductive Film (NCF). 12.8 GB/s operation is achieved, while IO power was reduced by 89% compared to LPDDR3.