CMOS-Compatible Ti/Al Ohmic Contacts (Rc < 0.3 Ω mm) for u-AlGaN/AlN/GaN HEMTs by Low Temperature Annealing (< 450 °C)

Abstract

Recently the development of CMOS-compatible fabrication technologies for GaN HEMTs has attracted increasing levels of interest. A low temperature ohmic contact technology is required for gate-first device fabrication and CMOS-first GaN-Si integration process, however, typical ohmic contacts need annealing at > 800°C. In the past, we have reported an approach to realize low contact resistance (R[subscript C]) using CMOS-compatible metal schemes annealed at 500°C through an n[superscript +]-GaN/n-AlGaN/GaN structure [4]. This method has a drawback that the n-doped AlGaN barrier increases the gate leakage current. In this work, we present the first low temperature (< 450°C) CMOS-compatible Ti/Al ohmic contact technology for conventional unintentionally-doped AlGaN/AlN/GaN HEMT structures.