3D stacked devices without area penalty from device-device space, such as complementary FET (CFET), is promising for post-nanosheet CMOS scaling. New MOL architectures, such as backside power delivery network (BSPDN) or Vertical-Horizontal-Vertical routing style, are required to connect 3D stacked devices without wiring congestions and resistance increase. Process/material innovations are necessary to enable high aspect ratio and 3D integration in CFET integration with new MOL architectures.