Metamorphic InAlAs/InGaAs HEMT MMIC Technology on GaAs Substrate: From Promise to Reality
M. Chertouk, F. Benkhelifa, M. Dammann, M. Walther, K. Kohler,
Franhofer Institute for Applied Solid State Physics (IAF), Tullastrase 72, D-79108 Freiburg, Germany
We report on fabrication, performance and reliability of metamorphic InAlAs/InGaAs high electron mobility transistors on GaAs substrates (MHEMTs). The MHEMT shows a measured maximum stable gain of 12 db at 118 GHz, giving an extrapolated fmax of 480 GHz. The stage W-band amplifiers with 18 db gain and 30 GHz bandwidth are demonstrated. The robustness of our MMICs technology with MHEMTs is demonstrated by high temperature stress at 250oC for 2000 hours. DC accelerated life tests were made on devices with 0.25 mm gate length at different temperatures and 1 V drain bias. From an Arrhenius plot an activation energy of 2 eV and MTTF of 2.106 hours at a channel temperature of 150oC was obtained.
Furthermore a 0.5 mm low cost high performance metamorphic HEMT process on 4-inch GaAs substrates is demonstrated. Excellent uniformity of DC and HF characteristics were obtained across 4" GaAs substrates. An fT or 53 GHz and a fmax of 200 GHz was obtained for 0.5mm gate length passivated and a with 300 nm SiN. The standard deviation of the threshold voltage is 23 to 35 mV from wafer to wafer. These results show the potential of a low cost technology to manufacture a high volume production MMICs with MHEMTs on 4" GaAs substrates using an i-line stepper for applications from 2 to 77 GHz.