Impacts of though-DRAM vias in 3D processor-DRAM integrated systems

As a promising option to address the memory wall problem, 3D processor-DRAM integration has recently received many attentions. Since DRAM tiers must be stacked between the processor tier and package substrate, we must fabricate a large number of through-DRAM through-silicon vias (TSVs) to connect the processor tier and package for power and I/O signal delivery. Although such through-DRAM TSVs will inevitably interfere with DRAM design and induce non-negligible power consumption overhead, little research has been done to study how to allocate these TSVs on the DRAM tiers and analyze their impacts. To address this open issue, this paper first presents a through-DRAM TSV allocation strategy that fits well to the regular DRAM architecture. To demonstrate this design strategy and evaluate trade-offs involved, we develop a CACTI-based modeling tool to carry out extensive simulations over a wide range of design parameters.