Cathode device having a small aperture and its method of manufacture

摘要

A device (100) forming a cathode comprises a plurality of emitter points (2) which have conically tipped end parts (2A) used for emitting electrons. A grid electrode layer (4) has an opening (4A) in which the end tip part of each of the emitter points is exposed. The diameter of the opening made in the grid electrode layer is made smaller than that for the part of the emitter point located at the junction thereof with the substrate. In manufacture of the cathode device, an oxide layer is formed at least on the surface of the emitter point formed in order to make it more acute. Once the oxide layer has been withdrawn, the inner circumferential part of the opening in the grid electrode layer is formed on the outside of the conically tipped end part of the emitter point and extends approximately parallel to the conically tipped part of the emitter point. <IMAGE>