The Cu metalized GaAs pHEMTs using developed Pd/Ni/Ge/Mo/Cu and Cu/Ge based ohmic contacts and Ti/Mo/Cu 150 nm T-shape gate has been successfully fabricated for the high-frequency applications. The fabricated Cu metalized GaAs pHEMTs with Pd/Ni/Ge/Mo/Cu and Ge/Cu ohmic contacts had a transconductance peak of 440 and 320 mS/mm, maximum stable gain value was about 18.8 and 14.5 dB at frequency 10 GHz and current gain cut-off frequency was about 100 and 60 GHz, accordingly. The performance of the fully Cu metalized atomic hydrogen treated GaAs pHEMT with Cu/Ge ohmic contacts and Ti/Mo/Ge/Cu based T-gate was investigated. It was found, that such processing in an atomic hydrogen flow with density 10¹⁵ at. cm² s^-1 at room temperature during 5 min leads to reduce the contact resistance of Ge/Cu ohmic contacts by 1.6 times. The reduction in specific contact resistance is apparently caused by the action of the hydrogen atoms which minimise the rate of the oxidizing reactions and activate solid phase reactions forming the ohmic contact during the thermal treatment process. The fabricated fully Cu metalized GaAs pHEMT with atomic hydrogen processing had a transconductance peak of 380 mS/mm and current gain cut-off frequency was about 80 GHz. It is similar with performance of conventional gold base devices. The experimental results allow to consider the copper as perspective gold replacement in the GaAs MMIC production.

Date Published: 8 January 2013
PDF: 7 pages
Proc. SPIE 8700, International Conference Micro- and Nano-Electronics 2012, 87000M (8 January 2013); doi: 10.1117/12.2016911

Published in SPIE Proceedings Vol. 8700:
International Conference Micro- and Nano-Electronics 2012
Alexander A. Orlikovsky, Editor(s)