CMOS BEOL-compatible monolithic integration of high-temperature functional materials using on-chip microheaters

Incompatibility of high-temperature processes on CMOS chips hinders the monolithic integration of demanding materials, which limits the capability of current silicon photonics. We present a CMOS back -end-of-line (BEOL)-compatible monolithic integration pla tform, utilizing on-chip microheaters. These microheaters create localized heat at micro-devices (temperature up to 850 °C), while keeping most areas of the chip within the BEOL thermal budget. Through parallel microheater operation, we further achieve high-throughput optimization of deposition and annealing conditions. As a demonstration, we show high-temperature annealing of yttrium iron garnet (YIG) films for their crystallization, which creates magneto-optical isolators on silicon photonics. Our approach opens a new paradigm for heterogeneous integration of emerging materials and thus novel devices for silicon photonics.