Reliability of aluminum-bearing ohmic contacts to SiC under high current density

Brian P. Downey, Suzanne E. Mohney, Trevor Edward Clark, Joseph R. Flemish

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The degradation produced by high current density stressing of a contact to p-SiC consisting of an Al-bearing ohmic contact, a TiW diffusion barrier, and a thick Au overlayer was studied. The test structure allowed for vertical current stressing and the measurement of the specific contact resistance before and after stressing. A threshold current for contact failure was established for the Ti/Al and W/Al contacts, at which a large increase in specific contact resistance was measured and extensive voiding occurred in the ohmic contact region. The high current stressing generated a flux of Al from the ohmic contact layer, through the TiW barrier, to the surface to be oxidized, along with a flux of Au into the ohmic contact layer. The voiding in the ohmic contact layer, caused by the unequal fluxes of Al and Au, decreased the active area of the contact, consequently increasing the current density and the associated effects from electromigration and Joule heating, initiating a runaway event.

Original languageEnglish (US)
Pages (from-to)1967-1972
Number of pages6
JournalMicroelectronics Reliability
Volume50
Issue number12
DOIs
StatePublished - Dec 1 2010

Fingerprint

Bearings (structural)
Ohmic contacts
Aluminum
high current
electric contacts
Current density
current density
aluminum
Contact resistance
Fluxes
contact resistance
Joule heating
Diffusion barriers
Electromigration
electromigration
threshold currents
degradation
Degradation
heating

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Safety, Risk, Reliability and Quality
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering

Cite this

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abstract = "The degradation produced by high current density stressing of a contact to p-SiC consisting of an Al-bearing ohmic contact, a TiW diffusion barrier, and a thick Au overlayer was studied. The test structure allowed for vertical current stressing and the measurement of the specific contact resistance before and after stressing. A threshold current for contact failure was established for the Ti/Al and W/Al contacts, at which a large increase in specific contact resistance was measured and extensive voiding occurred in the ohmic contact region. The high current stressing generated a flux of Al from the ohmic contact layer, through the TiW barrier, to the surface to be oxidized, along with a flux of Au into the ohmic contact layer. The voiding in the ohmic contact layer, caused by the unequal fluxes of Al and Au, decreased the active area of the contact, consequently increasing the current density and the associated effects from electromigration and Joule heating, initiating a runaway event.",
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Reliability of aluminum-bearing ohmic contacts to SiC under high current density. / Downey, Brian P.; Mohney, Suzanne E.; Clark, Trevor Edward; Flemish, Joseph R.

In: Microelectronics Reliability, Vol. 50, No. 12, 01.12.2010, p. 1967-1972.

Research output: Contribution to journalArticle

TY - JOUR

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AU - Downey, Brian P.

AU - Mohney, Suzanne E.

AU - Clark, Trevor Edward

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AB - The degradation produced by high current density stressing of a contact to p-SiC consisting of an Al-bearing ohmic contact, a TiW diffusion barrier, and a thick Au overlayer was studied. The test structure allowed for vertical current stressing and the measurement of the specific contact resistance before and after stressing. A threshold current for contact failure was established for the Ti/Al and W/Al contacts, at which a large increase in specific contact resistance was measured and extensive voiding occurred in the ohmic contact region. The high current stressing generated a flux of Al from the ohmic contact layer, through the TiW barrier, to the surface to be oxidized, along with a flux of Au into the ohmic contact layer. The voiding in the ohmic contact layer, caused by the unequal fluxes of Al and Au, decreased the active area of the contact, consequently increasing the current density and the associated effects from electromigration and Joule heating, initiating a runaway event.

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