A method for manufacturing semiconductor-integrated electronic circuits comprises: depositing an auxiliary layer on a substrate; depositing a layer of screening material on the auxiliary layer; selectively removing the layer of screening material to provide a first opening in the layer of screening material and expose an area of the auxiliary layer; and removing this area of the auxiliary layer to form a second opening in the auxiliary layer, whose cross-section narrows toward the substrate to expose an area of the substrate being smaller than the area exposed by the first opening.