Electrochemical behavior of cobalt in post-via etch cleaning solutions

S. Bilouk, C. Pernel, L. Broussous, V. Ivanova, R. P. Nogueira

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

6 Scopus citations


The integration of CoWP and CoWB self-aligned barriers (SAB) for 32 nm technology nodes allows improving copper interconnections reliability [1, 3]. However the introduction of such materials in copper interconnection levels drives new challenges for plasma dry etch and wet clean processes. Indeed, during the post-via-etch cleaning step, cobalt and copper can be altered by corrosion. Moreover, a galvanic coupling between cobalt, the major component of SAB, and copper can thermodynamically occur. In this way, the cleaning solution acts as ionic medium providing a contact between the two metals. Thus, both metals polarize to a mixed potential comprised between the individual open circuit potentials (OCP) of cobalt and copper. As a result, the less noble metal can suffer from accelerated corrosion, and the more noble metal corrodes with slower rate. According to thermodynamic aspects, cobalt in contact with copper is the less noble metal. Consequently, Co is susceptible to undergo galvanic corrosion which may enhance the dissolution of the SAB.

Original languageBritish English
Title of host publicationUltra Clean Processing of Semiconductor Surfaces IX
Subtitle of host publicationUCPSS 2008
Number of pages4
StatePublished - 2009
Event9th international symposium on Ultra Clean Processing of Semiconductor Surfaces, UCPSS 2008 - Bruges, Belgium
Duration: 22 Sep 200824 Sep 2008

Publication series

NameSolid State Phenomena
ISSN (Print)1012-0394


Conference9th international symposium on Ultra Clean Processing of Semiconductor Surfaces, UCPSS 2008


  • Cobalt
  • Corrosion
  • Post-via etch clean
  • Self aligned barrier


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