In situ Surface Passivation of Gallium Nitride for Metal-Organic Chemical Vapor Deposition of High-Permittivity Gate Dielectric

We report the demonstration of novel techniques for surface passivation of gallium nitride (GaN), comprising the steps of in situ vacuum anneal (VA) and silane-ammonia (SiH 4 + NH 3 ) or silane (SiH 4 ) treatment for GaN, prior to the formation of high-permittivity gate dielectric in a multichamber metal-organic chemical vapor deposition tool. The effects of VA temperature and the SiH 4 + NH 3 or SiH 4 treatment temperature on interface quality was investigated. High-temperature capacitance-voltage characterization was also performed to probe the interface states near the midgap of GaN. Interface state density D it as a function of energy was extracted. Without in situ passivation, a control TaN/HfAlO/GaN capacitor has a midgap D it of ~2.0 × 10 12 cm -2 · eV -1 . This is reduced to ~4.0 × 10 11 cm -2 · eV -1 and ~2.0 × 10 10 cm -2 · eV -1 for samples that received the in situ SiH 4 + NH 3 treatment and in situ SiH 4 treatment, respectively.