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Comparison of pd/sn and pd/sn/au thin-film Systems for Device Metallization

Published online by Cambridge University Press:  15 February 2011

M. S. Islam
Affiliation:
Microelectronics Research Laboratory, School of Electronic Engineering, Dublin City Unliversity, Dublin 9, Ireland
Patrick J. Mcnally
Affiliation:
Microelectronics Research Laboratory, School of Electronic Engineering, Dublin City Unliversity, Dublin 9, Ireland
D. C. Cameron
Affiliation:
Electronic Materials Research Laboratory, School of Electronic Engineering, Dublin City University, Dublin 9, Ireland
P. A. F. Herbert
Affiliation:
Plasma Ireland Ltd., Enterprise Centre, North Mall, Cork, Ireland
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Abstract

An Ohmic contact system comprising of Pd/Sn metallization has been developed for n-GaAs and compared with Pd/Sn/Au metallization. Surface morphology of the contacts is investigated using surface profilometry measurements and Scanning Electron Microscopy (SEM). The contact depth profiles are analyzed by Secondary Ion Mass Spectrometry (SIMS). Contact resistivities, Pc, of the proposed metallizations are measured using a conventional Transmission Line Model (TLM) method. A lowest ρc, of ∼2.07×10−5 Ω-cm2 was obtained with a Pd(50 nm)/Sn(125 nm) contact on 2×1018 cm−3 n-GaAs after annealing at 400 °C for 30 min. A Au overlayer improves the characteristics of the Pd/Sn contacts. The Pd(50 nm)/Sn(125 nm)/Au(100 nm) contact shows a lowest ρc of ∼1.29×10−6 Ω-cm2 after annealing at 330 °C for 30 min. The Pd/Sn/Au contacts exhibit superior properties compared to those of alloyed five-layer Au/Ge/Au/Ni/Au contacts.

Type
Research Article
Copyright
Copyright © Materials Research Society 1996

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