Design and Testing Strategies for Modular 3-D-Multiprocessor Systems Using Die-Level Through Silicon Via Technology

An innovative modular 3-D stacked multi-processor architecture is presented. The platform is composed of completely identical stacked dies connected together by through-silicon-vias (TSVs). Each die features four 32-bit embedded processors and associated memory modules, interconnected by a 3-D network-on-chip (NoC), which can route packets in the vertical direction. Superimposing identical planar dies minimizes design effort and manufacturing costs, ensuring at the same time high flexibility and reconfigurability. A single die can be used either as a fully testable standalone chip multi-processor (CMP), or integrated in a 3-D stack, increasing the overall core count and consequently the system performance. To demonstrate the feasibility of this architecture, fully functional samples have been fabricated using a conventional UMC 90 nm complementary metal-oxide-semiconductor process and stacked using an in-house, via-last Cu-TSV process. Initial results show that the proposed 3-D-CMP is capable of operating at a target frequency of 400 MHz, supporting a vertical data bandwidth of 3.2 Gb/s.