Skip to Main Content
The effect of CVD-SiO2 films on the reliability of GaAs MESFET with Ti/Pt/Au gate metal was investigated. It was found that the mean time to failure (MTTF) of MESFET with 350°C-depositied SiO2 was only about one-seventh of that of the ones with 440°C-SiO2. It was also found that, in the storage test at 300°C for 24 hours, diffusion of Pt into GaAs was accelerated when the SiO2 deposition temperature was lower than 380°C. FT-IR spectra indicated that the lower deposition temperature leads to a higher concentration of the residual hydrogen in SiO2. Thermal differential spectrometry (TDS) demonstrated that hydrogen in SiO2 could migrate even below 300°C. In conclusion, the residual hydrogen in SiO2 causes the degradation phenomena.