Fabrication of High Breakdown Pseudomorphic Modulation Doped Field Effect Transistors Using Double Dry Etched Gate Recess Technology in Combination with E-Beam T-Gate Lithography

Abstract

We have developed a technology to fabricate pseudomorphic 0.3 µ m gatelength modulation doped field-effect transistors (MODFETs) having a breakdown voltage up to 20 Volts. This technology uses molecular beam epitaxy (MBE) to grow the InGaAs/AlGaAs/GaAs heterostructure with two pulse doping layers on 3 inch semiisolating GaAs wafers. A mix and match lithography was applied using an i-line stepper and an electron beam direct write process to define the mushroom shaped gates (T-gates). The breakdown enhancement is achieved by a self aligned selective double dry etched gate recess using AlGaAs etch stop layers. We investigated the heterostructure doping and the influence of the gate recess process to the device performance.