| Abstract |
Copper thin films are increasingly important as interconnectors for the creation of smaller and better performing integrated circuits and electrodeposition from ionic liquid-based electrolytes could provide a greener fabrication method for these films. The electrodeposition of copper from copper(I) and copper(II) salt solutions in a low cost, widely available ionic liquid, 1-ethyl-3-methylimidazolium ethylsulphate, was studied using a range of different deposition potentials and temperatures. Three different electrolytes containing similar to 0.1 M of copper(I) chloride(CuCl), copper(II) chloride (CuCl2) and copper(II) sulphate (CuSO4) were used. Under similar deposition conditions, the films obtained from CuCl and CuSO4-based electrolytes presented better continuity than films obtained from CuCl2-based electrolyte. Continuous films with a homogeneous structure were obtained by electrodeposition from CuCl and CuSO4-based solutions at a constant potential of -1.8 V and a temperature of 35 A degrees C. Under similar deposition parameters, the films deposited from CuCl2-based electrolyte presented the largest particle size, while those deposited from copper(I) chloride and CuSO4-based solutions presented finer microstructures. X-ray diffraction analysis and energy dispersive X-ray spectroscopy showed that the deposits were crystalline and consisted mainly of copper, with traces of oxygen and sulphur resulting from residues of the ionic liquid. The films presented a nanocrystalline microstructure consisting of particles about 25 nm, aggregated in clusters. |
