BEOL-compatible monolithic integration of property-tunable complex oxide single crystals on Si for advancing the more-than-Moore paradigm

Complex oxide single-crystal thin films offer diverse functionalities essential for advancing the More-than-Moore paradigm in semiconductor technology. However, their direct integration with Si-based complementary metal-oxide-semiconductor (CMOS) circuits remains challenging due to thermal budget constraints and the difficulty of applying oxide-engineering techniques—such as strain, interface, and domain engineering— for tailoring properties on silicon. In this work, we demonstrate room-temperature monolithic integration of complex oxides onto silicon by combining epitaxial lift-off and surface-activated metal bonding, effectively overcoming thermal limitations. This method allows the application of oxide-engineering methodologies on silicon substrates, as demonstrated using ferromagnetic SrRuO3, ferroelectric Pb(Mg,Nb)O3-Pb(Zr,Ti)O3, and induced-ferroelectric SrTiO3. Moreover, we highlight its practical potential through the fabrication of flexible ferroelectric heterostructures and electrically-controllable energy storage devices with a one-transistor, one-capacitor structure. This integration strategy facilitates the incorporation of emergent oxide functionalities into CMOS via back-end-of-line (BEOL) processes, bridging complex oxide science with silicon technology for advancing the More-than-Moore paradigm.