Forming of a microelectronic device including a substrate containing at least one conductive pad, the pad being provided with a bottom surface resting on the substrate and an upper surface opposite the bottom surface. The upper surface of the pad has a stack applied thereto formed of a conductive layer and a protective dielectric layer including an opening called first opening facing the pad and exposing the conductive layer. At least one insulating block is arranged on a peripheral region of the upper surface of the pad, the insulating block having a cross-section forming a closed contour and having an opening called second opening. A conductive pillar is located in the center of the contour in the second opening.