0.1-/spl mu/m p/sup +/-GaAs gate HJFETs with f/sub T/=121 GHz fabricated using all dry-etching and selective MOMBE growth

Abstract

This paper reports the first successful fabrication of a high-performance, 0.1-/spl mu/m, T-shaped, p/sup +/-gate pseudomorphic heterojunction-FET (HJFET) using all dry-etching and selective MOMBE growth techniques. We have developed a two-step dry-etching technique that compensates for the poor dry-etching resistance of PMMA, and a voidless gate-electrode filling technique for high aspect-ratio openings with selective MOMBE p/sup +/-GaAs growth. Our efforts results in a reduction of external gate fringing capacitance and a improvement in gate turn-on voltage. The fabricated 0.1-/spl mu/m, p/sup +/-gate n-Al/sub 0.2/Ga/sub 0.8/As-In/sub 0.25/Ga/sub 0.75/As HJFET exhibits excellent microwave performance, f/sub T/=121 GHz and f/sub max/=144 GHz.