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Characterisation of nickel silicide thin films by spectroscopy and microscopy techniques

Madhu Bhaskaran 1Sharath Sriram 1Anthony S. Holland 1Peter J. Evans 2

1. RMIT University, Sch. of Elec. and Comp. Engg., Microelectronics and Materials Technology Centre (RMIT), GPO Box 2476V, Melbourne, Victoria, Melbourne 3001, Australia
2. Australian Nuclear Science and Technology Organisation, Institute of Environmental Research (ANSTO), PMB 1, Menai, New South Wales, Sydney 2234, Australia


Nickel silicide (NiSi) is the material currently used to define local interconnects in the CMOS industry. It is also highly suitable for microsystems fabrication, exhibiting suitable mechanical properties and good resistance to bulk micromachining etchants. This paper discusses the formation and detailed materials characterisation of nickel silicide thin films. Nickel silicide thin films have been formed by thermally reacting electron beam evaporated thin films of nickel with silicon. Nickel, on formation of nickel silicide, consumes about 1.83 nm of silicon for every nm of metal, resulting in 2.54 nm of silicide. It was observed that the metal step height of 50 nm had reduced to 25 nm on (100) n-type samples after nickel silicide formation.

The nickel silicide thin films have been analysed using Auger Electron Spectroscopy (AES) depth profiles, Secondary Ion Mass Spectrometry (SIMS), and Rutherford Backscattering Spectroscopy (RBS). The AES depth profile shows a uniform NiSi film, with a composition of 49-50 % nickel and 51-50 % silicon. No oxygen contamination on the surface or at the silicide-silicon interface was observed. SIMS depth profile confirms the existence of a uniform film, with no traces of oxygen contamination. RBS results indicate a nickel silicide layer of 114 nm, with the simulated spectra in close agreement with obtained data. Atomic Force Microscopy has been used to study the surface morphology of the nickel silicide thin films. The average grain size and average surface roughness of these films was found to be 25 nm and 0.67 nm respectively. The film surface has also been imaged using high resolution scanning electron micrographs, and studied using Kikuchi patterns obtained by electron back-scatter detection.


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Presentation: Poster at E-MRS Fall Meeting 2007, Symposium J, by Madhu Bhaskaran
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-04-30 14:22
Revised:   2009-06-07 00:44