Three-dimensional (3D) on-chip memory stacking has been proposed as a promising solution to the "memory wall" challenge with the benefits of low access latency, high data bandwidth, and low power consumption. The stacked memory tiers leverage through-silicon vias (TSVs) to communicate with logic tiers, and thus dramatically reduce the access latency and improve the data bandwidth without the constraint of I/O pin count.
To demonstrate the feasibility of 3D memory stacking, this paper introduces a 3D system-on-chip (SOC) for H.264 applications that can make use of multiple memory channels offered by 3D integration. Two logic tiers are stacked together with a 3-layer 8- channel 3D DRAM stacked on the top. The design flow for this 3D SOC is also presented. The prototype chip has been fabricated with GlobalFoundries' 130-nm low-power process and Tezzaron’s 3D TSV technology. The 3D implementation shows that the 3D ICs can alleviate the pressure from I/O pin count and allow parallel memory accesses through multiple channels.