Thermal stability of Ti, Pt, and Ru interfacial layers between seedless copper and a tantalum diffusion barrier

Xin Liu, Sean W. King, Robert Nemanich

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Abstract

The thermal stability of 7 nm Ti, Pt, and Ru interfacial adhesion layers between Cu film (10 nm) and a Ta barrier layer (4 nm) has been investigated. The barrier properties and interfacial stability have been evaluated by Rutherford backscattering spectrometry (RBS). Atomic force microscopy was used to measure the surfaces before and after annealing, and all the surfaces are relatively smooth which excludes islanding or dewetting phenomena as a cause of the instability. The RBS showed no discernible diffusion across the adhesion layer/Ta and Ta/Si interfaces which provides a stable underlying layer. For a Ti interfacial layer, RBS indicates that during 400 °C annealing, Ti interdiffuses through the Cu film and accumulates at the surface. For the Pt/Cu system, Pt interdiffusion is detected which is less evident than Ti. Among the three adhesion layer candidates, Ru shows negligible diffusion into the Cu film indicating thermal stability at 400 °C.

Original languageEnglish (US)
Article number022205
JournalJournal of Vacuum Science and Technology B:Nanotechnology and Microelectronics
Volume31
Issue number2
DOIs
Publication statusPublished - 2013

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ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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