An electronic semiconductor device has a sublithographic contact area (45, 58) between a first conductive region (22) and a second conductive region (38). The first conductive region (22) is cup-shaped and has vertical walls which extend, in top plan view, along a closed line of elongated shape. One of the walls of the first conductive region forms a first thin portion and has a first dimension in a first direction. The second conductive region (38) has a second thin portion (38a) having a second sublithographic dimension in a second direction (X) transverse to the first dimension. The first and the second conductive regions are in direct electrical contact at their thin portions and form the sublithographic contact area (45, 58). The elongated shape is chosen between rectangular and oval elongated in the first direction. Thereby, the dimensions of the contact area remain approximately constant even in presence of a small misalignment between the masks defining the conductive regions.