Preparation and characterization of metal/sapphire and metal/polyimide thin film laminates
Peddada, Satyanarayana Rao
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https://hdl.handle.net/2142/21833
Description
Title
Preparation and characterization of metal/sapphire and metal/polyimide thin film laminates
Author(s)
Peddada, Satyanarayana Rao
Issue Date
1991
Doctoral Committee Chair(s)
Birnbaum, Howard K.
Department of Study
Materials Science and Engineering
Discipline
Materials Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Metallurgy
Engineering, Materials Science
Language
eng
Abstract
The aim of this research program was to understand the effect of thermal cycling on metal/insulator (sapphire and polyimide, PI) thin film laminates through studies of microstructure and microchemistry. Systems studied were: Ti/sapphire, Au/Cu/Ti/PI/Si and Cr/Cu/Cr/PI/Si. In the Ti/sapphire system, there was an additional interest to understand the effect of growth temperature on growth orientation and crystal quality of the films. The three material systems were characterized by a number of analytical techniques such as cross-section TEM (XTEM), plan-view TEM, SEM, Auger Electron Spectroscopy and X-ray diffraction. Of these, XTEM was the most extensively used.
In the Ti/sapphire system, single crystals formed in the temperature range 245-750$\sp\circ$C with the respective close packed planes and directions parallel. The crystal quality improved with an increase in the growth temperature up to 750$\sp\circ$C. The interface was observed to be sharp with no reaction layer formation even at a growth temperature of 950$\sp\circ$C. On annealing in D$\sb2$ gas at 325$\sp\circ$C for 48 hours, the Ti film transformed to TiD$\sb2,$ but no mechanical failures were observed.
In the Ti/PI system, on annealing in D$\sb2$ gas at 325$\sp\circ$C for 48 hours, the interface remained sharp to a large extent, but a discontinuous reaction zone consisting of an oxide, $\rm Ti\sb5O\sb9,$ formed at the interface due to a reaction between Ti and moisture in the PI. On annealing in D$\sb2$ gas, spontaneous edge delamination was observed at the Ti/PI interface. There was no extensive diffusion of Ti or Cu into PI even in samples annealed at 400$\sp\circ$C for 48 hours.
In the Cr/PI system, the interface remained sharp after annealing at 325$\sp\circ$C irrespective of the ambient atmosphere. Tensile cracks formed due to residual thermal stresses. There was no significant diffusion of Cr or Cu into PI on annealing at 325$\sp\circ$C for 48 hours.
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