Patent ID: 7785164

Claim:
A method for manufacturing a triode cathode structure including, on one face of a substrate and stacked together, a resistive layer, a cathode layer structured to form cathode conductors, a layer made of an electrically insulating material, and a grid layer structured to form grid conductors, the method comprising the following successive steps: depositing the resistive layer on the face of the substrate; depositing the cathode layer made of an electrically conducting material on the resistive layer; structuring the cathode layer as cathode conductors arranged in one structure chosen among either a rows structure or a columns structure; depositing the layer of electrically insulating material on the cathode conductors and the resistive layer; depositing the grid layer made of an electrically conducting material on the layer of the electrically insulating material; structuring the grid layer as grid conductors arranged in another structure chosen among either the rows structure or the columns structure; etching the grid layer structured as grid conductors, the electrically insulating layer, and the cathode layer structured as cathode conductors until reaching the resistive layer so as to provide cavities at an intersection of grid conductors and cathode conductors, wherein this etching step includes, a) depositing a resin layer on the grid layer structured as grid conductors, b) obtaining, by lithography and development of the resin layer, openings in the resin layer organized according to a pattern that will form emissive pads at the bottom of the cavities, c) etching the grid layer structured as grid conductors, according to the pattern, d) etching the electrically insulating layer subjacent to the grid layer structured as grid conductors by extending the etching beyond emissive pad patterns to obtain a width of the cavity greater than the width of the pads, e) etching the grid layer structured as grid conductors at zones exposed by etching of the electrically insulating layer in step d) until reaching the resin layer and etching the cathode layer structured as cathode conductors at zones exposed by the etching of the electrically insulating layer in step d) until the resistive layer is reached so as to give a perforated structure to the cathode layer structured as cathode conductors at the intersection of the cathode conductors and the grid conductors, f) depositing a catalyst layer in openings of the resin layer so as to form emissive pads at the bottom of the cavities, and g) eliminating the resin layer and obtaining the triode cathode structure.