A method for producing a capacitor stack in one portion of a substrate, the method including: forming a cavity along a thickness of the portion of the substrate from an upper face of the substrate, depositing a plurality of layers contributing to the capacitor stack onto the wall of the cavity and onto the surface of the upper face, and removing matter from the layers until the surface of the upper face is reached. The forming of the cavity includes forming at least one trench and, associated with each trench, at least one box. The at least one trench includes a trench outlet that opens into the box. The box includes a box outlet that opens at the surface of the upper face, and the box outlet being shaped to be larger than the trench outlet.