Formation of NiCoSix silicide by thermal annealing of Ni/Co bilayer on Si substrate

Ohsung Song, Dugjoong Kim, C. S. Yoon, C. K. Kim

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Silicides used as contact materials in integrated circuits have to meet strict material requirements: thermal stability and<50 nm in thickness with<5 Ω/sq in sheet resistance. Instead of using a single-phased silicide, a composite silicide structure with optimal electrical properties has been proposed. In this research, 15 nm-Ni/15 nm -Co/p-Si(1 0 0) was thermally annealed using rapid thermal annealing (RTA) for 40 s at 700-1100 °C. The annealed bilayer structure developed into composite NiCoSix and resulting changes in sheet resistance, composition and microstructure were studied using Auger electron spectroscopy and transmission electron microscopy. The final thickness of the composite NiCoSix was approximately 50 nm and maintained its sheet resistance of 5 Ω/sq after annealing at 1100 °C. A possible reason suggested for the improved thermal stability was the formation of Ni-enriched NiCoSix with low interfacial energy at the substrate interface. When the NiCoSix films were additionally annealed at 900-1100 °C for 30 min, the sheet resistance for the films remained low till 900 °C, then markedly increased due to the formation of stable (Ni1-xCox)Si2 phase. The proposed NiCoSix film was superior over the conventional single-phased silicide and can be easily incorporated into the sub-0.1 μm process due to its improved thermal stability.

Original languageEnglish
Pages (from-to)608-612
Number of pages5
JournalMaterials Science in Semiconductor Processing
Issue number5
StatePublished - Oct 2005


  • Co/Ni composite silicide
  • Cobalt
  • Ni/Co bilayers
  • Nickel
  • Silicide


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