DC and microwave performance of submicrometer InGaAs HIGFETs

The DC and microwave performance of InAlAs/InGaAs/InP heterostructure insulated-gate FETs (HIGFETs) with gate lengths down to 0.3 μm is reported. A non-recessed-gate process with refractory airbridge gates and self-aligned contact implants was used to assure minimum threshold variation, minimum parasitic resistance, and minimum gate leakage current. These devices offer improved threshold uniformity while preserving the high-speed characteristic of In_0.53Ga _0.47As channels. An average of eight HIGFETs with 1.1-μm gate length showed peak DC transconductance of 456±5 mS/mm and on-state resistance of 1.14±0.02 Ω-mm. The output conductance was relatively high, about 60 mS/mm without wide-bandgap buffers. Full S-parameter measurements from 0.5 to 25.5 GHz were used to determine the unity-current-gain frequency, f_t=28 GHz, and the unity-power-gain frequency, f _mag=27 GHz. HIGFETs with 0.6-μm gate length showed improved DC and RF performance, with peak transconductance of 528±3 mS/mm, on-state resistance of 0.84±0.2 Ω-mm, f_t=45 GHz, and f_mag=36 GHz. Some short-channel effect is evident in the output conductance. HIGFETs with 0.3-μm gate length showed severe short-channel effect. With the addition of a wide-bandgap buffer layer and adjustments to the implant process, control of the short-channel effect at smaller gate lengths should be practical