In situ surface passivation of gallium nitride for metalOrganic chemical vapor deposition of high-permittivity gate dielectric

Abstract

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 (SiH4 + NH3) or silane (SiH4) treatment for GaN, prior to the formation of high-permittivity gate dielectric in a multichamber metalorganic chemical vapor deposition tool. The effects of VA temperature and the SiH4 + NH3 or (SiH4) treatment temperature on interface quality was investigated. High-temperature capacitancevoltage characterization was also performed to probe the interface states near the midgap of GaN. Interface state density Dit as a function of energy was extracted. Without in situ passivation, a control TaN/HfAlO/GaN capacitor has a midgap Dit of ∼2.0 × 10 12cm-2. -emlV-1. This is reduced ∼4.0 × 1011 cm-2 .-eV-1 and ∼2.0 × 1010 cm-2.-emlV -1 for samples that received the in situ SiH4 + NH 3 treatment and in situ SiH4 treatment, respectively. © 2010 IEEE.