Pointed-cone array field emission tripolar structure and manufacturing method therefor

Abstract

The invention discloses a pointed-cone array field emission tripolar structure and a manufacturing method therefor. The structure comprises a cathode substrate, an oxidation layer, metal pointed cones, and a graphene grid electrode. The interior of each cavity of the oxidation layer is provided with a metal pointed cone, and the metal pointed cones jointly form a metal pointed cone array. The oxidation layer is disposed on the cathode substrate, and the graphene grid electrode is disposed on the oxidation layer. The structure employs the graphene grid electrode to replace a conventional metal grid electrode, and the preparation flow is different from the preparation flow of a conventional Spindt-type field emission array to some extent. After the forming of the pointed cones and the cleaning of foreign matters, the oxidation layer is covered by a single graphene layer or a little of graphene, so as to serve as the grid electrode. On the one hand, the pointed cones and the metal foreign matters in the cavities are effectively washed before the preparation of the graphene grid electrode, thereby reducing the cathode grid risks; on the other hand, the graphene layer can form a more uniform electric field below the grid electrode, thereby effectively reducing the voltage needed by the pointed cones for electron emission.

Description

technical field [0001] The invention relates to a tapered array field emission triode structure using single-layer or few-layer graphene as a gate and a manufacturing method thereof, belonging to the technology of vacuum electronic devices. Background technique [0002] Spindt cathode is the earliest field emission cathode developed. It has excellent performance and can realize high current density and large total current in a small area at the same time, which is very suitable for microwave power devices. When the operating frequency rises to the terahertz frequency band, the device requires the cathode current density to exceed 100A / cm 2 , other cathodes are difficult to meet the requirements. In the initial stage of vacuum microelectronics research, almost all field emission application researches have tried this cathode, but the reliability of the Spindt type field emission cathode is not high, which limits its application development. The main problems are local exces...

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Problems solved by technology

[0003] First, the metal particle impurities produced in the process of deposition and fabrication of the emission tip fall off when the separation layer is peeled off, and they adhere to the surface of the emission tip, the edge of the gate and the silicon dioxide cavity carrying the tip, especially some cavities Internal deposits are difficult to remove completely

The presence of these metal particle deposits will lead to the failure of the initial cathode and become a potential hidden danger in the later application

[0004] Second, the traditional Spindt cathode cleans the impurities inside after the structure is fabricated. On the one hand, the impurities inside the cavity cannot be effectively removed, and these deposited particles are hidden inside the cavity under the grid. It can be seen from the SEM observation that However, the existence of these particles will affect the electric field distribution inside the cone and the cavity and the cathode-grid short circuit

On the other hand, if the removal time and intensity are too large, the grid may crack or even the cone may fall off.

[0005] Third, during the Spindt cathode fabrication process, SiO 2 During the removal process, the cavity under the gate will be corroded, and the distance between the emission cones in the array is often relatively close, which makes only part of the SiO under the gate layer 2 support, when SiO 2 When the bonding force between the insulating layer and the metal gate is insufficient to support the deposition of the separation layer and the metal closure layer above the gate, the gate will crack, which will cause cathode-grid short circuit and arc damage in the later test

[0006] Fourth, the inhomogeneity of the electric field due to the difference in the structure of each cathode grid causes the inhomogeneity of each emitter, which is prone to local excessive emission and leads to the failure of the entire cathode

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