Journal of the Korean Institute of Electrical and Electronic Material Engineers (한국전기전자재료학회논문지)

The Korean Institute of Electrical and Electronic Material Engineers (한국전기전자재료학회)
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Conduction Properties of NitAI Ohmic Contacts to AI-implanted p-type 4H-SiC

AI 이온 주입된 p-type 4H-SiC에 형성된 Ni/AI 오믹접촉의 전기 전도 특성

  • 주성재 (한국전기연구원 재료응용연구본부 에너지반도체연구센터) ;
  • 송재열 (동의대학교 전자공학과) ;
  • 강인호 (한국전기연구원 재료응용연구본부 에너지반도체연구센터) ;
  • 방욱 (한국전기연구원 재료응용연구본부 에너지반도체연구센터) ;
  • 김상철 (한국전기연구원 재료응용연구본부 에너지반도체연구센터) ;
  • 김남균 (한국전기연구원 재료응용연구본부 에너지반도체연구센터) ;
  • 이용재 (동의대학교 전자공학과)
  • Published : 2009.09.01
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Abstract

Ni/Al ('/' denotes deposition sequence) contacts were deposited on Al-implanted 4H-SiC for ohmic contact formation, and the conduction properties were characterized and compared with those of Ni-only contacts. The thicknesses of the Ni and Al thin film were 30 nm and 300 nm, respectively, and the films were sequentially deposited bye-beam evaporation without vacuum breaking. Rapid thermal anneal (RTA) temperature was varied as follows : $840^{\circ}C$, $890^{\circ}C$, and $940^{\circ}C$. The specific contact resistivity of the Ni contact was about $^{\sim}2\;{\pm}\;10^{-2}\;{\Omega}{\cdot}cm^2$, However, with the addition of Al overlayer, the specific contact resistivity decreased to about $^{\sim}2\;{\pm}\;10^{-4}\;{\Omega}{\cdot}cm^2$, almost irrespective of RTA temperature. X-ray diffraction (XRD) analysis of the Ni contact confirmed the existence of various Ni silicide phases, while the results of Ni/Al contact samples revealed that Al-contaning phases such as $Al_3Ni$, $Al_3Ni_2$, $Al_4Ni_3$, and $Ab_{3.21}Si_{0.47}$ were additionally formed as well as the Ni silicide phases. Energy dispersive spectroscopy (EDS) spectrum showed interfacial reaction zone mainly consisting of Al and Si at the contact interface, and it was also shown that considerable amounts of Si and C have diffused toward the surface. This indicates that contact resistance lowering of the Ni/Al contacts is related with the formation of the formation of interfacial reaction zone containing Al and Si. From these results, possible mechanisms of contact resistance lowering by the addition of Al were discussed.

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