Alternatively, the adhesion/barrier layer at the bottom of the adhesion/barrier/seed layer 8011 may be formed by sputtering a titanium???tungsten-alloy layer with a thickness of between 0.02 and 0.8 ??m, and preferably of between 0.05 and 0.5 ??m, on the polymer layer 95 and on the pads, principally made of copper, exposed by the openings 950 in the polymer layer 95.