Enabling area efficient RF ICs through monolithic 3D integration

The Monolithic 3D (M3D) integration technology has emerged as a promising alternative to dimensional scaling thanks to the unprecedented integration density capabilities and the low interconnect parasitics that it offers. In order to support technological investigations and enable future M3D circuits, M3D design methodologies, flows and tools are essential. Prospective M3D digital applications have attracted a lot of scientific interest. This paper identifies the potential of M3D RF/analog circuits and presents the first attempt to demonstrate such circuits. Towards this, a M3D custom design platform, which is fully compatible with commercial design tools, is proposed and validated. The design platform includes process characteristics, device models, LVS and DRC rules and a parasitic extraction flow. The envisioned M3D structure is built on a commercial CMOS process that serves as the bottom tier, whereas a SOI process is used as top tier. To validate the proposed design flow and to investigate the potential of M3D RF/analog circuits, a RF front-end design for Zig-Bee WPAN applications is used as case-study. The M3D RF front-end circuit achieves 35.5 % area reduction, while showing similar performance with the original 2D circuit.