Al 이온 주입된 p-type 4H-SiC에 형성된 Ni/Ti/Al Ohmic Contact의 전기적 특성

Electrical Characteristics of Ni/Ti/Al Ohmic Contacts to Al-implanted p-type 4H-SiC

  • 주성재 (한국전기연구원 재료응용연구단 고집적전원연구그룹) ;
  • 송재열 (동의대학교 전자공학과) ;
  • 강인호 (한국전기연구원 재료응용연구단 고집적전원연구그룹) ;
  • 방욱 (한국전기연구원 재료응용연구단 고집적전원연구그룹) ;
  • 김상철 (한국전기연구원 재료응용연구단 고집적전원연구그룹) ;
  • 김남균 (한국전기연구원 재료응용연구단 고집적전원연구그룹)
  • 발행 : 2008.11.01


Ni/Ti/Al multilayer system ('/'denotes the deposition sequence) was tested for low-resistance ohmic contact formation to Al-implanted p-type 4H-SiC. Ni 30 nm / Ti 50 nm / Al 300 nm layers were sequentially deposited by e-beam evaporation on the 4H-SiC samples which were implanted with Al (norminal doping concentration = $4\times10^{19}cm^{-3}$) and then annealed at $1700^{\circ}C$ for dopant activation. Rapid thermal anneal (RTA) temperature for ohmic contact formation was varied in the range of $840\sim930^{\circ}C$. Specific contact resistances were extracted from the measured current vs. voltage (I-V) data of linear- and circular transfer length method (TLM) patterns. In constrast to Ni contact, Ni/Ti/Al contact shows perfectly linear I-V characteristics, and possesses much lower contact resistance of about $2\sim3\times10^{-4}\Omega{\cdot}cm^2$ even after low-temperature RTA at $840^{\circ}C$, which is about 2 orders of magnitude smaller than that of Ni contact. Therefore, it was shown that RTA temperature for ohmic contact formation can be lowered to at least $840^{\circ}C$ without significant compromise of contact resistance. X-ray diffraction (XRD) analysis indicated the existence of intermetallic compounds of Ni and Al as well as $NiSi_{1-x}$, but characteristic peaks of $Ti_{3}SiC_2$, a probable narrow-gap interfacial alloy responsible for low-resistance Ti/Al ohmic contact formation, were not detected. Therefore, Al in-diffusion into SiC surface region is considered to be the dominant mechanism of improvement in conduction behavior of Ni/Ti/Al contact.



  1. B. J. Baliga, "Silicon carbide power devices", World Scientific Publishing Co. Pte. Ltd., p. 16, 2005
  2. S.-J. Kim, "Effect on metal guard ring in breakdown characteristics of SiC Schottky barrier diode", J. of KIEEME(in Korean), Vol. 18, No. 10, p. 877, 2005
  3. M. W. Cole and P. C. Joshi, "Silicon carbide : materials, processing, and devices", (edited by Z. C. Feng and J. H. Zhao), Taylor & Francis, p. 252, 2004
  4. V. Heera, D. Panknin, and W. Skorupa, "p-Type doping of SiC by high dose Al implantation - problems and progress", Appl. Surf. Sci., Vol. 184, p. 307, 2001
  5. S. Tanimoto, N. Kiritani, M. Hoshi, and H. Okushi, "Ohmic contact structure and fabrication process applicable to practical SiC devices", Mater. Sci. Forum, Vol. 389, p. 879, 2002
  6. J. Crofton, L. Porter, and J. Williams, "The physics of ohmic contacts to SiC", Phys. Status Solidi B, Vol. 202, p. 581, 1997<581::AID-PSSB581>3.0.CO;2-M
  7. B. J. Johnson and M. A. Capano, "Mechanism of ohmic behavior of Al/Ti contacts to p-type 4H-SiC after annealing", J. Appl. Phys., Vol. 95, p. 5616, 2004
  8. R. Konishi, R. Yasukochi, O. Nakatsuka, Y. Koide, M. Moriyama, and M. Murakami, "Development of Ni/Al and Ni/Ti/Al ohmic contact materials for p-type 4H-SiC", Mat. Sci. Eng. B, Vol. 98, p. 286, 2003
  9. S. Tsukimoto, T. Sakai, and M. Murakami, "Electrical properties and microstructure of ternary Ge/Ti/Al ohmic contacts to p-type 4H-SiC", J. Appl. Phys., Vol. 96, p. 4976, 2004
  10. D. K. Schroder, "Semiconductor material and device characterization", John Wiley & Sons, Inc., p. 154, 1998

피인용 문헌

  1. Conduction Properties of NitAI Ohmic Contacts to AI-implanted p-type 4H-SiC vol.22, pp.9, 2009,