Fabrication of a 0.1-mu m T-shaped gate with wide head for super low noise HEMTs

Abstract

This paper reports on the fabrication of a 0.1-mu m T-shaped gate with wide head for super low noise HEMTs (high election mobility transistors). For the optimization of the HEMT, the SPACING (spacing between the footprint and the head patterns) and the dosage for the head and the footprint were investigated by experiment and Monte Carlo simulation to define 0.1-mu m T-shaped gates with wide heads at 30-kV acceleration voltages. The footprint of a 1-pixel line is to be 0.1 mu m and the head size is to be larger than 1 mu m when the dosage of the footprint is 700 mu C/cm(2) and the SPACING is 3 pixels and the head dosage is 60 mu C/cm(2). Using these optimized conditions, a T-shaped gate at the 0.1-mu m level with a high ratio of gate head size to footprint, larger than 10, was obtained, and a AlGaAs/InGaAs/GaAs pseudomorphic HEMT with a 0.13-mu m T-shaped gate was successfully fabricated. The HEMT device exhibited very low noise figures of 0.34 dB and 0.49 dB at 12 GHz and 18 GHz, respectively.