Self-Aligned-Gate Digital AlGaAs/GaAs Modulation-Doped Field Effect Transistor (MODFET) Processing And Short Channel Effects

Self-aligned-gate digital AlGaAs/GaAs MODFETs have been fabricated with gate lengths from 1.3 to 0.35 pm. A "T"cross-section gate formed by reactive ion etching (RIE) is employed. Rapid thermal annealing (RTA) is used for implant activation and ohmic contact alloying. High temperature stability of layer structures grown by molecular-beam epitaxy (MBE)and of refractory gate metallization is presented. Finally, a comparison of device characteristics is made for pulse-doped MODFETs with and without superlattice buffers, with emphasis on short channel effects.