Download Study of the deposition and interaction mechanisms of aluminium

Study of the deposition and interaction mechanisms of aluminium and
copper designed surfaces
Roberto Gaggiano
PhD SUMMARY
Within this thesis the mechanism of two different depositions (a chemical and an
electrochemical based) system are investigated.
The first part of this thesis is focused on the study of the adsorption of soluble silicates
with the anodic alumina surface, with particular relation to lithographic applications.
Aluminium substrates with different oxide films are considered, such as native oxide,
barrier oxides and porous oxides of different thicknesses. A few studies exist on the
interaction of silicates with aluminium oxides and the mechanism of silicate deposition
on alumina is not clear. Therefore, the aim of this first part of the work was to
characterize the silicate / aluminum oxide system in order obtain a better understanding
of how the silicate interacts with anodic alumina and how this interaction is influenced by
the morphology of the oxide and the characteristics of the solution. The anionic
speciation in the silicate solution was studied by means of 29Si-NMR.Complementary
surface analysis techniques were used to study the deposition of soluble silicate on the
surface of porous anodic alumina. The morphological changes occurring on the oxide
surface were observed by Field Emission Scanning Electron Microscopy. Wavelength
Dispersive X-Ray Fluorescence measurements allowed quantifying the deposited silicate
on the porous oxide layer. The presence of silicate in the pores of the anodic layer was
then studied by means of Auger Electron Spectroscopy and Glow Discharge Optical
Emission Spectroscopy. A mechanism of deposition is proposed in this work.
The second part of this work is the analysis of the effect of the microstructure of copper
on the adsorption of gold particles in aqueous solution. It is known in literature that the
reactivity of metals and alloys is influenced by the grain orientation of the material. The
aim of this part of the thesis was to characterize the gold/copper system in order obtain a
better understanding of how the grain orientation of the material affects the deposition of
gold particles. The grain distribution and orientation of the copper substrate is studied by
means of Electron BackScatter Diffraction, Field Emission Scanning Electron
Microscopy and Energy Dispersive X-ray analysis. Significant differences in the amount
of deposited gold were observed, depending on the grain orientation of the material.
Therefore, the deposition of gold particles is presented as a new method for the
investigation of the reactivity of grains and grain boundaries on copper.