A method for manufacturing a microelectronic semiconductor device comprising the steps of: forming a trench in a body, the trench having side walls, a opening, and a bottom; forming a sacrificial layer in the trench; forming a recess in the sacrificial layer; forming a restriction structure between the sacrificial layer and the opening of the trench, defining a through hole for access to the sacrificial layer; completely removing the sacrificial layer through said through hole; and depositing a metal layer over the body, thus closing the opening of the trench and forming an electron-emission cathode tip.