CEA-Leti at IEDM 2023 today described the world-s-first 3D sequential integration (3DSI) of CMOS over CMOS with advanced metal line levels, which brings 3DSI with intermediate BEOL closer to commercialization.-
This breakthrough, detailed in the paper -3D Sequential Integration with Si CMOS Stacked on 28nm Industrial FDSOI with Cu-ULK iBEOL Featuring RO and HDR Pixel-, stems from the demonstration of a monocrystalline CMOS stacked sequentially above an industrial CMOS platform (28nm FDSOI) and four metal levels. The top CMOS device process was carried out at 500°C in a FEOL 300mm fabrication above state-of-the art CU/ULK 28nm BEOL. -
-This achievement establishes the feasibility of manufacturing high-performance silicon CMOS devices above an industrial platform, including state-of-the-art BEOL, without compromising the performance of the bottom layer. It allows reaching the full potential of 3DSI with top devices having high performance, low variability and CMOS co-integrability in contrast with BEOL transistors,- said Perrine Batude, a co-author of the paper and leader of 3DSI integration in CEA-Leti.
Full 3DSI, in which monocrystalline CMOS devices are stacked above an industrial CMOS process, specifically when it integrates an intermediate BEOL (iBEOL) with Cu and ULK, previously has eluded researchers.
-This work aims to demonstrate such integration, provide methodologies to achieve it, and analyze the performance of 3D circuits,- the paper explains.