GE-BASED HIGH MOBILITY CHANNEL TRANSISTORS FOR LOW POWER LOGIC AND BACK-END-OF-LINE COMPATIBLE 3D INTEGRATED CIRCUITS

Abstract

Focusing on Ge-based materials and devices, this thesis investigates the influence of strain engineering as well as quantum confinement effects on electrical properties, unveiling their great potential in applications ranging from high performance logic circuits to high capacity 3D-monolithic integrated systems. Theoretical calculation and Raman measurements disclose that uniaxial compressive strain can be realized in GeSn Fins with scaled Fin width. In addition, quantum confinement effects have been comprehensively studied in this dissertation, from the aspects of both simulation and experiment. Our exploration shows a significant suppression of leakage current can be observed in Ge-based transistors with sub-10 nm channel thickness, which indicates an enlarged bandgap due to quantum effects. Ge-based techniques have promising prospects in the emerging 3D monolithic integration as well due to its low process temperature. In this thesis, we demonstrate a heterogeneous integration between Ge pFET and IGZO nFET for high performance BEOL-compatible CMOS circuit, which can be a key enabler in future 3D monolithic integrated systems.