Continuous single-crystal germanium films using elevated-laser-liquid-phase-epitaxy technique for monolithic 3D integration

Abstract In this study, we present a novel elevated-laser-liquid-phase-epitaxy (ELLPE) technique that has been developed for the fabrication of single-crystal germanium (Ge) films with (100) orientation, which is ideal for monolithic three-dimensional integrated circuits (3D ICs). The crystalline quality and orientation of the ELLPE Ge films were validated using scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy. Additionally, heat transfer dynamics during the laser crystallization process were analyzed through COMSOL Multiphysics simulations. More significantly, the ELLPE technique maintains the temperature of the underlying silicon (Si) substrate below the critical 400 °C thermal budget, ensuring full compatibility with monolithic 3D integration processes. The combination of low thermal budget and high-quality single-crystal Ge film states ELLPE technique as a promising method for enhancing the performance of future monolithic 3D ICs.