A design tradeoff study with monolithic 3D integration

This paper studies various design tradeoffs existing in the monolithic 3D integration technology. Different design styles in monolithic 3D ICs are studied, including transistor-level monolithic integration (MI-TR) and gate-level integration (MI-G). GDSII-level layout of monolithic 3D designs are constructed and analyzed. Compared with its 2D counterparts, MI-TR designs have advantages in footprint area, wire-length, timing, and power, because of the smaller footprint. MI-G design style also demonstrate advantages in area, timing and power over TSV-based designs, because of the smaller size and parasitics of inter-tier vias compared with TSVs. To further take the advantage of monolithic 3D technology, several technology improvement options are also explored. Besides, some possible design challenges with monolithic 3D are also studied, including global variation and signal integrity issues.