Challenges of contact module integration for GaN-based devices in a Si-CMOS environment

The authors report on the integration of an Au-free contact module intended for AlGaN/GaN high-electron-mobility transistors fabricated in a 200 mm Si complementary metal-oxide-semiconductor facility. Contacts are characterized via transfer line method structures, tunneling electron microscopy, and energy-dispersive x-ray spectroscopy. Factors leading to incorrect extraction of contact resistance are discussed. The authors find that reoptimization of chemical vapor deposited silicon nitride on AlGaN/GaN substrates is required to ensure reliable determination of contact resistance, gate-to-source spacing, and gate-to-drain spacing. Additional process development is required to enable parallel processing of Si and GaN devices.