50 nm InGaAs/InAlAs/GaAs metamorphic high electron mobility transistors using double exposure at 50 kV electron-beam lithography without dielectric support

Abstract

We are presenting a technology to fabricate InGaAs/InAlAs/GaAs metamorphic high electron mobility transistors (MHEMTs) with a gate length of 50 nm without a thin dielectric supporting layer. This technology uses a ZEP520/P(MMA-MAA)/PMMA trilayer by double exposure at 50 kV electron-beam lithography. The fabricated 50 nm MHEMTs with a 70 μm unit gate width and two fingers were characterized through dc and rf measurements. The maximum drain current density and transconductance (gm) were 180 mA/mm and 713 mS/mm, respectively. From rf measurements, we obtained the current gain cut-off frequency of 218.8 GHz.