Recently, Network-on-Chip (NoC) architectures have gained popularity to address the interconnect delay problem for designing CMP / multi-core / SoC systems in deep sub-micron technology. However, almost all prior studies have focused on 2D NoC designs. Since three dimensional (3D) integration has emerged to mitigate the interconnect delay problem, exploring the NoC design space in 3D can provide ample opportunities to design high performance and energy-efficient NoC architectures. In this paper, we propose a 3D stacked NoC router architecture, called MIRA, which unlike the 3D routers in previous works, is stacked into multiple layers and optimized to reduce the overall area requirements and power consumption. We discuss the design details of a four-layer 3D NoC and its enhanced version with additional express channels, and compare them against a (6×6) 2D design and a baseline 3D design. All the designs are evaluated using a cycle-accurate 3D NoC simulator, and integrated with the Ori...