0.5 micrometer E/D AlGaAs/GaAs heterostructure field effect transistor technology with DFET threshold adjust implant

摘要

A doped-channel heterostructure field effect transistor (H-FET) technology has been developed with self-aligned refractory gate processing and using both enhancement- and depletion-mode transistors. D-HFET devices are obtained with a threshold voltage adjust implant into material designed for E-HFET operation. Both E- and D-HFETs utilize W/WSi bilayer gates, sidewall spacers, and rapid thermal annealing for controlling short channel effects. The 0.5 micrometers E-HFETs (D-HFETs) have been demonstrated with transconductance of 425 mS/mm (265-310 mS/mm) and f(sub t) of 45-50 GHz. Ring oscillator gate delays of 19 ps with a power of 0.6 mW have been demonstrated using direct coupled FET logic. These results are comparable to previous doped-channel HFET devices and circuits fabricated by selective reactive ion etching rather than ion implantation for threshold voltage adjustment.