NiGeAu Ohmic Contact in InGaP pHEMTs
Ellen Lan, Qianghua Xie, Peter Fejes, and Ha Le,
Motorola Inc., Semiconductor Products Sector
Phone: (480) 413-4128, Fax: (480) 413-4453, Email: firstname.lastname@example.org
Keywords: InGaP/InGaAs pHEMT, ohmic contacts, NiGeAu, annealing, contact resistance, TEM
NiGeAu ohmic contact as a function of alloying temperature on InGaP/InGaAs pHEMT structure was investigated. It was found that the optimum RTA condition is 460 °C 60 sec for n+ contact resistance, whereas 420 °C 30 sec for on-resistance. Electron microscope examinations of the cross-sectional samples annealed at these two conditions revealed three types of alloy grains. Chemical compositions of these grains were obtained by the nano-probe X-ray energy dispersive spectrum (EDS) analysis. A correlation between these alloy grains and the contact resistance and on-resistance was established.