JPS6086728A - Field emitter - Google Patents

Abstract

PURPOSE:To gain a stable field emitter with high brightness by decreasing carbon defect of transition metalic carbide by solid solution of nitrogen and/or oxygen. CONSTITUTION:A field emitter is formed by using transition metalic compound which is represented by a general formula MCxOyNz (M is a single or more than two sorts of solid solution of transition metal of IV, V and VI family, and the relationship 0.5<x+Y+z<=1,0,5<=x<=1,0<y<=0.5,0<=z<=0.5, may be satisfied but y and z are not zero at the same time). For example, a single crystal of TiC0.96 whose composition is controlled by a suspended zone method is manufactured, and the crystal is cut out so that axes of <100>, <111> and <110> may coincide with an emissive axis, and the tip end is formed to a radius of curvature less than 0.1 by an electrolytic abrasion. After exposing it to the atmosphere with 1 atmospheric pressure and making adsorption of oxygen and nitrogen, it is heated at 1,000 deg.C for 10min for annealing.

Description

Detailed Description of the Invention The present invention relates to an electron beam exposure machine, a high brightness electron beam utilization machine a.
Regarding the field emitter used.

Tungsten has been used as a conventional field emitter material, and attempts have been made to use transition metal carbides.

However, when using tungsten, residual gases are adsorbed to the surface because tungsten is an active metal.
The adsorbed atoms diffuse onto the radiation surface. -6゛ and move. Therefore, there is a drawback that the local work on the radiation surface is limited.

Additionally, when using transition metal carbides, they are more inert in reacting with residual gas than tungsten, but their activity is closely related to the number of carbon defects on the emitting surface.
As the number of defects increases, the surface activity increases, and the fluctuation range of the electron beam thermodynamically exists in a non-stoichiometric region across the tongue. 4 to 9 faceted carbon defects are introduced.

The object of the present invention is to create a radiation surface that is more inert with respect to reaction with residual gas due to carbon defects inevitably introduced in transition metal carbides, and to provide a stable, high-brightness field emitter. be.

The present inventors have demonstrated that a stable high-brightness field emitter can be obtained by reducing carbon defects in transition metal oxides by incorporating nitrogen and/or oxygen into solid solution.

Transition metal carbides, transition metal oxides, and transition metal nitrides all have the same rock salt crystal structure and have similar chemical bonds, so they form a solid solution with each other, and this solid solution reduces the number of carbon defects. I can do it.

Furthermore, the solid solution of vrr oxygen lowers the work function of the radiation surface and has the effect of emitting electrons efficiently. Also, nitrogen,
The solid solution of the element improves thermal conductivity and has the effect that flash heating for cleaning the radiation surface can be performed more efficiently.

Since the smaller the number of carbon defects, the more stable the radiation surface becomes.
General formula MCxOyNz (where M is M of the ■, ■, ■ group
Represents a solid solution of a single or two or more types of transfer metals. ), it is desirable that X + y + z-1 be close to 1h, but even if it is not necessarily 1, it can be stabilized by making it a solid solution.

Valid composition ranges are as follows.

0.5 x × 1, O<y<, 0.5, O<: Z<
0, 51p; However, y and 2 are never 0 at the same time 7■, V, W group transition metals include Ti, Z
r, Hf.

Examples include V, Nb, Ta, Mo, and W, and these may be used alone or as a solid solution.

In addition, the method of dissolving oxygen or nitrogen into carbon defects within the above range may be by introducing oxygen (or nitrogen) gas in vacuum and heating it at 1000°C, or by introducing oxygen (or nitrogen) gas at 1 atm. ) After exposing the emitter in gas, 1
Heat treatment may be performed at 000°C. Furthermore, the same effect can be obtained by dissolving oxygen (or nitrogen) gas in the crystal during crystal growth.

Next, Examples will be given to demonstrate the excellent effects of the field emitter of the present invention.

Comparative Example A Tie, 6 single crystal whose composition was controlled by the floating zone method was prepared and cut out so that the (100), (111), and (110) axes coincided with the radial axis. The tip was electrolytically polished to a radius of curvature of 0.1μ or less, and the field emission was examined in an ultra-high vacuum of 91, Opa.

<100> The surface of the chip had defects of more than ten atomic percent. The change in radiation current over time in this chip was as shown in FIG. As shown in Figure 1, the radiation current from this surface undergoes step and spike-like fluctuations.
It also decreased over time.

This tendency was also observed for the (111) and <110> chips.

<100>, <110 in the same manner as in Examples and Comparative Examples
, (110) was prepared, exposed to the atmosphere at 1 atm to adsorb oxygen and nitrogen, and then heated at 1000°C for 10
Annealed by heating for 1 minute, and field-treated in the same manner as the comparative example.
Adjust the emissions. The emitted current change over time in this (100') chip was as shown in FIG. As this figure shows, the emitted current was extremely stable and remained stable even after 10 hours. This tendency was also observed for the (111>chip and <110>chip.

11. In the examples, T is used as a representative transition metal.
Although i is listed, Zr, Hf, V, Nb, Ta %
Similar results are obtained for No. and W as well.

As described above, the field emitter of the present invention exhibits an excellent effect that the emission current is extremely stable over a long period of time compared to the conventional field emitter.

[Brief explanation of drawings]

FIG. 1 shows a time-varying diagram of the radiation current in a conventional field emitter having carbon defects of more than ten atomic percent, and FIG. 2 shows a diagram of the radiation current over time in the field emitter of the present invention. Patent applicant Masaru Goto, Director, Inorganic Materials Research Institute, Science and Technology Agency j 1

Claims (1)

[Claims] The chemical composition of the material is the general formula, MCxOyN2 (where 1
(P\kulXOkuykuho5, 1' representing O<z<0.5
=5jp, 'g+y, and z are never 0 at the same time. ), characterized in that it consists of a transition metal compound represented by 'Ledo emitter. ]1