SkyBridge 2.0: A Fine-grained Vertical 3D-IC Technology for Future ICs

Gate-all-around FETs are set to replace FinFETs to enable continued miniaturization of ICs in the deep nanometer regime. IMEC and IRDS roadmaps project that 3D integration of gate-all-around FETs is a key path for the IC industry beyond 2024. In this paper, we present SkyBridge 2.0, an IC technology featuring high density fine-grained 3D integration of vertical gate-all-around nanowire FETs, contacts, and interconnect while also solving 3D routability. We utilize industry-standard EDA tools to develop a customized design and technology co-optimization (DTCO) flow to design and evaluate SkyBridge 2.0. This DTCO flow covers process emulation of standard cells and SRAM to enable scalable manufacturing pathway, TCAD characterization of vertical nanowire FETs to obtain IV and CV characteristics, compact modeling accurately the device behavior, RC parasitic extraction of 3D interconnects and performance, power and area assessment using ring oscillators. The technology assessment using ring oscillators shows that SkyBridge 2.0 at the chosen design point, using 10nm nanowires, achieves ∼ 18% performance and 31% energy efficiency benefits compared to 7nm FinFET technology. Area analysis of logic cells shows up to 6x density benefits versus aggressively scaled 2D-CMOS cells. In addition to logic, we architect 3D SRAM to support low-power memory designs. SkyBridge 2.0 SRAM shows ∼ 20% improvement in read and write static noise margin, up to  3x lower leakage current and up to 4x density benefits compared to 7nm FinFET technology.