0.15 micron gate AlInAs/GaInAs MHEMT fabricated on GaAs using deep-UV phase-shifting mask lithography

A 0.15 um gate process using a deep-UV stepper and phase-shifting mask lithography has been developed. This process eliminates the need for low throughput, direct write e-beam gate lithography. Using this process we have fabricated, for the first time, AlInAs/GaInAs MHEMTs on GaAs with f/sub t/'s up to 119 GHz. This optical approach for gate lithography is very attractive for manufacturing high volume, high performance, low cost GaAs integrated circuits.