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Estimation of Material Properties and Residual Stress Induced in Metallic Thin Films Synthesized by Thermal Sintering

Keikhaie, Mahdi | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44693 (08)
  4. University: Sharif University of Technology
  5. Department: Computer Engineering
  6. Advisor(s): Akbari, Javad; Movahhedy, Mohammad Reza
  7. Abstract:
  8. Thin films of materials, in order to have magnificent structure and properties, can use in complicated technology such as; electronic, optic and magnetic systems. Printed interconnects can be made by the deposition of suspensions of metal nanoparticles (e.g., silver and gold) followed by thermal sintering. The nanoparticle sintering process involves atomic diffusion resulting in shrinkage. As a result, the interconnects are prone to residual stresses generated during the thermal sintering process. The residual stress can cause cracks and delamination in the thin films and can cause permanent geometrical changes in the underlying substrates which may affect the functionality of the microelectronic devices. To estimate these residual stresses, mechanical properties of sintered film have required.
    In this thesis, an approach based on combination of modeling nanoparticles diffusion (equivalent geometry of sintered nanoparticles) and the classic continuum in order to estimate film’s properties has been presented. To achieve this aim, in first has been considered an element of silver nanoparticles and solving diffusion equations for them, sintered geometry is calculated. Then, through the simulation of the sintering process, it is shown that how the geometry, density, and electrical resistance of the thin film layer are changed with sintering conditions. The model is also used to approximate the values of the film Young’s modulus and residual stresses, because of different in coefficient of thermal expansion, in cooling phase from 150 ̊C to ambient temperature, without considering crack and cracked film. Comparing results with experimental results shows the high accuracy of this approach
  9. Keywords:
  10. Substrates ; Sintering ; Stong Equation ; Thin Films ; Nanoink

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