Energetics of ultrathin CoSi2 film on a Si(001) surface

Co disilicide has been considered to be one of the most attractive candidates for contact and interconnect materials in spite of problems such as the formation of pinholes and misoriented grains, and the difficulty of growing high-quality epitaxial CoSi2(100) films. We present a first-principles stu...

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Bibliographic Details
Published in:Journal of physics. Condensed matter 2003-01, Vol.15 (2), p.67-76
Main Authors: Kang, Byung Sub, Oh, Suhk Kun, Kang, Hee Jae, Sohn, Ki Soo
Format: Article
Language:English
Subjects:
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Condensed matter: structure, mechanical and thermal properties
Diffusion
interface formation
Electrical properties of specific thin films
Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures
Exact sciences and technology
Inorganic compounds
Metal and metallic alloys
Metals and metallic alloys
Physics
Solid surfaces and solid-solid interfaces
Structure of solids and liquids
crystallography
Structure of specific crystalline solids
Surfaces and interfaces
thin films and whiskers (structure and nonelectronic properties)
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Summary:Co disilicide has been considered to be one of the most attractive candidates for contact and interconnect materials in spite of problems such as the formation of pinholes and misoriented grains, and the difficulty of growing high-quality epitaxial CoSi2(100) films. We present a first-principles study on the structural stability of Co silicide phases and their magnetic properties for 1-2 monolayers (ML) of Co deposited on Si(001). The Co-Si interaction between the nearest neighbouring sites at the surface layer is strongly attractive. The formation of CoSi in the subsurface layer is energetically more favourable than that in a surface layer. The interdiffusion of a Co atom to the fourfold (tetrahedral) site is found to be energetically favourable. For surface alloy films of 1 and 2 ML Co on Si(001), there are no Co atoms at the surface due to the interdiffusion of Co atoms. The structural stability of the 'fourfold Si surface' model with the CoSi2 phase is compared with that of the six-fold model. Our result for the surface and interface of a thin CoSi2/Si(001) film is consistent with experimental and other theoretical data.
ISSN:0953-8984
1361-648X
DOI:10.1088/0953-8984/15/2/307