A semiconductor device, includes a semiconductor substrate (10) having a first (12a) and a second (12b) side. There is provided at least one via (15) extending through the substrate (10) having first (16a) and second (16b) end surfaces, the first end surface (16a) constituting a transducer electrode for interacting with a movable element (14) arranged at the first side (12a) of the substrate (10). A shield (17) is provided on and covers at least part of the first side (12a) of the substrate (10), the shield/mask (17) including a conductive layer (19a) and an insulating material layer (19b) provided between the substrate (10) and the conductive layer (19a). The mask has an opening (18) exposing only a part of the first surface (16a) of the via. Preferably the opening (18) in the mask is precisely aligned with the movable element, and the area of the opening is accurately defined.