Mask registration and lithography platform portability for nitride fin-based field effect transistors prototyping

Abstract

The authors report on the integration of a hybrid lithography process for AlGaN/GaN high-electron-mobility nanoscaled, fin-based field effect transistors with an Au-free contact. The integration consists of electron beam lithography (EBL) and optical photolithography to minimize prototyping cost and time while maximizing resolution and device array density. I-line direct photolithography is performed using standard photoresist, while EBL is accomplished using 2% polymethyl methacrylate for high resolution of fin structure patterning. Au-free contact is characterized using linear transmission line method (TLM) and is deposited along with registration marks via electron beam evaporation. The registration marks and TLM structures are used for alignment in the EBL process. Details of the device fabrication process and electrical results are discussed and show possible parallel processing of GaN and Si devices.