Innovative nitride passivation for pseudomorphic GaAs HEMTs and impact on device performance

A novel low temperature nitride deposition technique using high-density inductively coupled plasma chemical vapor deposition (HD-ICP-CVD) to passivate 0.15 /spl mu/m pseudomorphic GaAs HEMTs has been developed for the first time. SiH/sub 4//N/sub 2/ chemistries are used in HD-ICP-CVD for nitride deposition instead of SiH/sub 4//NH/sub 3//N/sub 2/ in plasma-enhanced CVD (PECVD). HD-ICP-CVD nitride films have a lower wet BOE etch rate and lower hydrogen concentration than those of nitride films deposited by PECVD. Nitride films with high density and low hydrogen concentration provide a potential improvement of hermeticity and reliability, which are crucial for MMIC insertion in the commercial arena. Furthermore, HD-ICP-CVD passivated devices exhibit better performance combinations of reverse breakdown voltage, transconductance, and cutoff frequency than those of PECVD passivated devices. The results achieved here warrant the application of HD-ICP-CVD for next-generation nitride passivation in compound semiconductor technologies.