Evaluation of electroless deposited Co(W,P) thin films as diffusion barriers for copper metallization

A. Kohn*, M. Eizenberg, Y. Shacham-Diamand, B. Israel, Y. Sverdlov

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

64 Scopus citations

Abstract

Electroless deposited Co(W,P) thin films were evaluated as diffusion barriers for copper metallization. Capacitance versus time measurements of MOS structures as well as SIMS depth profiles indicate that 30-nm-thick films can function as effective barriers against copper diffusion after thermal treatments up to 500 °C. The improved barrier properties relative to sputtered cobalt are explained by the incorporation of phosphorus (8-10 at.%) and tungsten (approximately 2 at.%) which most probably enrich the grain boundaries of the nanocrystalline hcp cobalt grains, forming a `stuffed' barrier. The phosphorus and tungsten additions stabilize the hcp crystalline structure of the cobalt grains, delaying the transition to the fcc phase by more than 80 °C compared to bulk pure cobalt. An advantage of this material compared to alternative diffusion barriers for copper is its relatively low resistivity of 80 μΩ cm.

Original languageEnglish
Pages (from-to)297-303
Number of pages7
JournalMicroelectronic Engineering
Volume55
Issue number1-4
DOIs
StatePublished - Mar 2001
Externally publishedYes

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