200 nm gate-length GaAs-based MHEMT devices by electron beam lithography

GaAs-based metamorphic HEMTs (MHEMT) consist of GaAs substrates and InP-based epitaxial structure, and have the advantages of both InP HEMT’s excellent performances and GaAs-based HEMT’s mature processes. GaAs-based MHEMTs were applied to millimeter-wave low-noise, high-power applications and systems. The current gain cut-off frequency (f _T) and the maximum oscillation frequency (f _max) are important performance parameter of GaAs-based MHEMTs, and they are limited by the gate-length mainly. Electron beam lithography is one of the lithography technologies which can be used to realize the deep submicron gate-length. The 200 nm gate-length GaAs-based MHEMTs have been fabricated by electron beam lithography. In order to reduce the parasite gate capacitance and gate resistance, a trilayer resist structure was used to pattern the T-gate resist profile. Excellent DC, high frequency and power performances have been obtained. F _T and f _max are 105 GHz, 70 GHz respectively. The research is very helpful to obtain higher performance GaAs-based MHEMTs. Supported by the National Basic Research Program of China (Grant No. G2002CB311901), Equipment Advance Research Project (Grant No. 61501050401C) and Institute of Microelectronics, Chinese Academy of Sciences, Dean Fund (Grant No. 06SB124004)