Investigation of diffusional intermixing in Si/Co/Ta system by Secondary Neutral Mass Spectrometry

A. Lakatos, G. Erdelyi, A. Makovec, G. A. Langer, A. Csik, K. Vad, D. L. Beke

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Low temperature analysis of diffusion and intermixing of Co-Si systems are very important in applications for microelectronics and Ultra Large Scale Integration (ULSI). In this communication a comprehensive report has been given on degradation and diffusion processes in the Si(substrate)/Co(150 nm)/Ta(10 nm) system. The samples were prepared by DC magnetron sputtering and were annealed in argon ambient at several temperatures ranging from 400 to 623 K for various times. The composition of the samples was investigated by Secondary Neutral Mass Spectrometry (SNMS). The degradation/intermixing starts with fast (grain boundary (GB)) diffusion of the Si into the Co layer. After some incubation time Si atoms appear and spread over the Co/Ta interface. This amount of Si accumulated at the Co/Ta interface acts as a reservoir for back-diffusion into the Co layer from the Co/Ta interface through the slower grain boundaries. At higher temperatures the formation of a Co-Si phase was detected at the Co/Si and Co/Ta interface. Three different diffusion coefficients were calculated from the SNMS concentration-depth profiles using "Central-gradient" (CG) and "First-appearance" methods. The observed intermixing was interpreted as a mixture of different "C-type" grain boundary diffusion processes. Furthermore, the experimental results are also compared with computer simulations modelling the grain-boundary diffusion through different grain-boundary paths. From the SNMS profiles measured at different temperatures the activation energy of the GB interdiffusion coefficients was deduced using the "CG method".

Original languageEnglish
Pages (from-to)724-728
Number of pages5
JournalVacuum
Volume86
Issue number6
DOIs
Publication statusPublished - Jan 27 2012

Keywords

  • SNMS technique
  • Si grain boundary diffusion in Co
  • Si/Co/Ta thin film

ASJC Scopus subject areas

  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films

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