Three-dimensional integration of two-dimensional field-effect transistors

In the field of semiconductors, three-dimensional (3D) integration not only enables packaging of more devices per unit area, referred to as 'More Moore'¹ but also introduces multifunctionalities for 'More than Moore'² technologies. Although silicon-based 3D integrated circuits are commercially available^3-5, there is limited effort on 3D integration of emerging nanomaterials^6,7 such as two-dimensional (2D) materials despite their unique functionalities^7-10. Here we demonstrate (1) wafer-scale and monolithic two-tier 3D integration based on MoS₂ with more than 10,000 field-effect transistors (FETs) in each tier; (2) three-tier 3D integration based on both MoS₂ and WSe₂ with about 500 FETs in each tier; and (3) two-tier 3D integration based on 200 scaled MoS₂ FETs (channel length, L_CH = 45 nm) in each tier. We also realize a 3D circuit and demonstrate multifunctional capabilities, including sensing and storage. We believe that our demonstrations will serve as the foundation for more sophisticated, highly dense and functionally divergent integrated circuits with a larger number of tiers integrated monolithically in the third dimension.