Engineering the Al-Ti/p-SiC Ohmic contact for improved performance

J. Y. Lin, Suzanne E. Mohney, M. Smalley, J. Crofton, J. Crofton, J. R. Williams, T. Isaacs-Smith

Research output: Contribution to journalArticle

Abstract

The influence of composition on Al-Ti ohmic contacts to 4H p-SiC was studied. When NA was 7 × 1018 cm-3, contacts with 70 wt.% or more Al became ohmic when annealed at 1000°C for 2 min, whereas when there was 60 wt.% or less Al, the contacts did not become ohmic even when annealed under more severe conditions (longer times and/or higher temperatures). Spiking of the contact metallization always accompanied ohmic behavior and could be correlated with Al-Ti compositions that contain both an Al-rich liquid and solid TiAl3 at 1000°C prior to reaction with SiC or evaporative loss of Al. For the 70 wt.% contacts, a specific contact resistance of 1.5 × 10-4 Ω•cm2 was measured along with spiking of the metallization into the SiC with a room-mean-square interfacial roughness of 150 Å and a maximum spiking depth of 1200 Å. Although still a concern, this spiking was less severe than observed for the 90 wt.% composition. A conductive CrB2 cap layer was next demonstrated to retard evaporation of Al during annealing of the Al-Ti contacts with 70 wt.% Al. The cap allowed use of thinner contact layers, reducing the depth of spiking and improving the surface morphology and edge definition of the ohmic contacts, with a one order of magnitude penalty in the specific contact resistance.

Original languageEnglish (US)
Pages (from-to)H7.3.1-H7.3.6
JournalMaterials Research Society Symposium-Proceedings
Volume640
StatePublished - Jan 1 2001

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spiking
Ohmic contacts
electric contacts
engineering
Contact resistance
Metallizing
Chemical analysis
contact resistance
caps
Surface morphology
Evaporation
Surface roughness
Annealing
penalties
Liquids
rooms
roughness
evaporation
annealing
Temperature

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

Lin, J. Y., Mohney, S. E., Smalley, M., Crofton, J., Crofton, J., Williams, J. R., & Isaacs-Smith, T. (2001). Engineering the Al-Ti/p-SiC Ohmic contact for improved performance. Materials Research Society Symposium-Proceedings, 640, H7.3.1-H7.3.6.
Lin, J. Y. ; Mohney, Suzanne E. ; Smalley, M. ; Crofton, J. ; Crofton, J. ; Williams, J. R. ; Isaacs-Smith, T. / Engineering the Al-Ti/p-SiC Ohmic contact for improved performance. In: Materials Research Society Symposium-Proceedings. 2001 ; Vol. 640. pp. H7.3.1-H7.3.6.
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abstract = "The influence of composition on Al-Ti ohmic contacts to 4H p-SiC was studied. When NA was 7 × 1018 cm-3, contacts with 70 wt.{\%} or more Al became ohmic when annealed at 1000°C for 2 min, whereas when there was 60 wt.{\%} or less Al, the contacts did not become ohmic even when annealed under more severe conditions (longer times and/or higher temperatures). Spiking of the contact metallization always accompanied ohmic behavior and could be correlated with Al-Ti compositions that contain both an Al-rich liquid and solid TiAl3 at 1000°C prior to reaction with SiC or evaporative loss of Al. For the 70 wt.{\%} contacts, a specific contact resistance of 1.5 × 10-4 Ω•cm2 was measured along with spiking of the metallization into the SiC with a room-mean-square interfacial roughness of 150 {\AA} and a maximum spiking depth of 1200 {\AA}. Although still a concern, this spiking was less severe than observed for the 90 wt.{\%} composition. A conductive CrB2 cap layer was next demonstrated to retard evaporation of Al during annealing of the Al-Ti contacts with 70 wt.{\%} Al. The cap allowed use of thinner contact layers, reducing the depth of spiking and improving the surface morphology and edge definition of the ohmic contacts, with a one order of magnitude penalty in the specific contact resistance.",
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Lin, JY, Mohney, SE, Smalley, M, Crofton, J, Crofton, J, Williams, JR & Isaacs-Smith, T 2001, 'Engineering the Al-Ti/p-SiC Ohmic contact for improved performance', Materials Research Society Symposium-Proceedings, vol. 640, pp. H7.3.1-H7.3.6.

Engineering the Al-Ti/p-SiC Ohmic contact for improved performance. / Lin, J. Y.; Mohney, Suzanne E.; Smalley, M.; Crofton, J.; Crofton, J.; Williams, J. R.; Isaacs-Smith, T.

In: Materials Research Society Symposium-Proceedings, Vol. 640, 01.01.2001, p. H7.3.1-H7.3.6.

Research output: Contribution to journalArticle

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T1 - Engineering the Al-Ti/p-SiC Ohmic contact for improved performance

AU - Lin, J. Y.

AU - Mohney, Suzanne E.

AU - Smalley, M.

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AU - Crofton, J.

AU - Williams, J. R.

AU - Isaacs-Smith, T.

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AB - The influence of composition on Al-Ti ohmic contacts to 4H p-SiC was studied. When NA was 7 × 1018 cm-3, contacts with 70 wt.% or more Al became ohmic when annealed at 1000°C for 2 min, whereas when there was 60 wt.% or less Al, the contacts did not become ohmic even when annealed under more severe conditions (longer times and/or higher temperatures). Spiking of the contact metallization always accompanied ohmic behavior and could be correlated with Al-Ti compositions that contain both an Al-rich liquid and solid TiAl3 at 1000°C prior to reaction with SiC or evaporative loss of Al. For the 70 wt.% contacts, a specific contact resistance of 1.5 × 10-4 Ω•cm2 was measured along with spiking of the metallization into the SiC with a room-mean-square interfacial roughness of 150 Å and a maximum spiking depth of 1200 Å. Although still a concern, this spiking was less severe than observed for the 90 wt.% composition. A conductive CrB2 cap layer was next demonstrated to retard evaporation of Al during annealing of the Al-Ti contacts with 70 wt.% Al. The cap allowed use of thinner contact layers, reducing the depth of spiking and improving the surface morphology and edge definition of the ohmic contacts, with a one order of magnitude penalty in the specific contact resistance.

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Lin JY, Mohney SE, Smalley M, Crofton J, Crofton J, Williams JR et al. Engineering the Al-Ti/p-SiC Ohmic contact for improved performance. Materials Research Society Symposium-Proceedings. 2001 Jan 1;640:H7.3.1-H7.3.6.