| Popis: |
An original approach for copper electroless deposition without the use of the palladium catalysts is developed. The mixture of two hydrophilic polymers, forming polymer–polymer complex and an assembly with ethylenediaminetetraacetic acid (EDTA)–Cu(II) one is the essential element of the method proposed. Two pairs compatible polymer mixtures (polyethylene glycol (PEG) – ethyl cellulose (EC) and PEG – poly(dimethylaminoethylmethacryloyl propanesulfonate), (PDMAPS) are tested. It is shown that these polymer additives do not change the UV- and EPR-spectra, as well as the current–voltage curve characteristics, which is related to the fact that in the presence of these polymer additives there is not the formation of new compounds with absorbance in the UV- and visible regions and new paramagnetic centers, as well as that they don’t influence the formaldehyde oxidation potential and Cu(II) reduction one. At the same time, these polymer additives decrease the deposition rate, improve the homogeneity, surface coverage and adhesion of the copper film to the substrate. These results correlate with the nonlinear viscosity elevation of the electroless bath with polymer additives, as well as with the maximal values of the critical angle for the first movement of the drop on the inclined substrate plane and of the difference between front and back contact angles of the drop from the electroless bath with polymer additives too. This correlation is related to the formation of the polymer–polymer complex, cross-linked with Cu(II)–EDTA as physical junction points, multisite adsorption of this enriched with Cu(II) network on the substrate surface, the precondition for a autocatalytic copper electroless deposition, more smooth substrate coverage, and improved adhesion of the copper film to the substrate surface. |
Full Text from ScienceDirect