SF₆O₂ plasma effects on silicon nitride passivation of AlGaNGaN high electron mobility transistors

The effects of various plasma and wet chemical surface pretreatments on the electrical characteristics of AlGaNGaN high electron mobility transistors (HEMTs) passivated with plasma-deposited silicon nitride were investigated. The results of pulsed IV measurements show that samples exposed to various S F6 O2 plasma treatments have markedly better rf dispersion characteristics compared to samples that were either untreated or treated in wet buffered oxide etch prior to encapsulation. The improvement in these characteristics correlates with the reduction of carbon on the semiconductor surface as measured with x-ray photoelectron spectroscopy. HEMT channel sheet resistance was also affected by varying silicon nitride deposition parameters.