Abstract: A method of manufacturing an electrical solid-state device in which the separation of adjacent areas of film material is controlled at a low value. The method employs established photoengraving techniques, and exploits the undermining of edges of photo-resist when the film material is etched away. The etching action is continued after exposure of the substrate, until the wall of film material recedes sufficiently to give a stable wall profile and a margin of exposed substrate which is overhung by photo-resist. Further film material is deposited on the substrate, but the margin, being sheltered by the overhanging photo-resist, remains uncovered.