The interfacial diffusion zone in magnetron sputtered Ni-Ti thin films deposited on different Si substrates studied by HR-TEM

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Abstract

Ni-Ti Shape Memory Alloy thin films are suitable materials for microelectromechanical devices. During the deposition of Ni-Ti thin films on Si substrates, there exist interfacial diffusion and chemical interactions at the interface due to the high temperature processing necessary to crystallize the film. For the present study, Ni-Ti thin films were prepared by magnetron co-sputtering from Ni-Ti and Ti targets in a specially designed chamber mounted on the 6-circle goniometer of the ROssendorf BeamLine (ROBL-CRG) at ESRF, Grenoble (France). The objective of this study has been to investigate the interfacial structure resulting from depositions (at a temperature of ≈470°C) on different substrates: naturally oxidized Si(100), Si(111) and poly-Si substrates. A detailed High-Resolution TEM analysis of the interfacial structure has been performed. When Ni-Ti is deposited on Si(100) substrate, a considerable diffusion of Ni into the substrate takes place, resulting in the growth of semi-octaeder A-NiSi2 silicide. In the case of Ni-Ti deposited on Si(111), there appears an uniform thickness plate, due to the alignment between substrate orientation and the [111]-growth front. For Ni-Ti deposited on poly-Si, the diffusion is inhomogeneous. Preferential diffusion is found along the columnar grains of poly-Si, which are favourably aligned for Ni diffusion. These results show that for the Ni-Ti/Si system, the morphology of the diffusion interface is strongly dependent on the type of substrates.

Original languageEnglish
Title of host publicationAdvanced Materials Forum IV
Subtitle of host publicationSelected, peer reviewed papers from the IV International Materials Symposium Materiais 2007 and XIII Encontro da Sociedade Portuguesa de Materiais - SPM
EditorsAntónio Torres Marques, António Fernando Silva, António Paulo Monteiro Baptista, Fernando Jorge Lino Alves, Carlos Sá, Luís Filipe Malheiros, Manuel Vieira
Place of PublicationZurich
PublisherTrans Tech Publications
Pages820-823
Number of pages4
ISBN (Print)9780878493739, 0878493735
DOIs
Publication statusPublished - 2008
EventAdvanced Materials Forum IV - Selected, peer reviewed papers from the 4th International Materials Symposium Materiais 2007 and 8th Encontro da Sociedade Portuguesa de Materiais - SPM - Porto, Portugal
Duration: 1 Apr 20074 Apr 2007

Publication series

NameMaterials Science Forum
Volume587-588
ISSN (Print)0255-5476
ISSN (Electronic)1662-9752

Conference

ConferenceAdvanced Materials Forum IV - Selected, peer reviewed papers from the 4th International Materials Symposium Materiais 2007 and 8th Encontro da Sociedade Portuguesa de Materiais - SPM
Country/TerritoryPortugal
CityPorto
Period1/04/074/04/07

Keywords

  • High-resolution TEM
  • Interfacial diffusion
  • Ni-Ti thin films
  • Shape memory alloy

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