Ultimate Monolithic-3D Integration With 2D Materials: Rationale, Prospects, and Challenges

TLDR

Monolithic 3D ICs using atomically thin 2D van der Waals materials are explored as a pathway to extend Moore’s law and enable beyond‑Moore heterogeneous integration by addressing key drawbacks of conventional 3D‑ICs such as low thermal budgets, inter‑tier signal delay, overheating, and electrical interference. The study aims to evaluate the feasibility of monolithic 3D integration with 2D materials to overcome the major limitations of current 3D‑ICs. The authors conduct a holistic assessment of electrical, thermal, and electromagnetic performance, including low‑temperature transfer‑free synthesis, heat‑dissipation analysis, and electrostatic/high‑frequency simulations of graphene screening and ILD scaling. The analysis shows that 2D‑based monolithic 3D integration can achieve more than tenfold higher integration density than TSV‑based 3D ICs and over 150 % improvement compared with conventional M3D, establishing 2D materials as a superior platform for ultra‑high‑density, ultra‑thin next‑generation electronics.

Abstract

As a possible pathway to continue Moore's law indefinitely into the future as well as unprecedented beyond-Moore heterogeneous integration, we examine the prospects of building monolithic 3D integrated circuits (M3D-IC) with atomically-thin or 2D van der Waals materials in terms of overcoming the major drawbacks of current 3D-ICs, including low process thermal budget, inter-tier signal delay, chip-overheating, and inter-tier electrical interference problems. Our holistic evaluation includes consideration of the electrical performance, thermal issues, and electromagnetic interference as well as attention to the synthesis methods necessary for low-temperature transfer-free 2D materials growth in M3D fabrication. Both in-plane and out-of-plane heat-dissipation in 3D-ICs made with 2D materials are evaluated and compared with those of bulk materials. Electrostatic and high-frequency electric-field simulations are conducted to assess the screening effect by graphene and effect of scaling down the inter-layer dielectric (ILD) thickness. Our analysis reveals for the first time that the 2D-based M3D integration can offer >ten-folds higher integration density compared with through-silicon-via (TSV)-based 3D integration, and >150% integration density improvement with respect to conventional M3D integration. Therefore, 2D materials provide a significantly better platform, with respect to bulk materials (such as Si, Ge, GaN), for realizing ultra-high-density M3D-ICs of ultimate thinness for next-generation electronics.