JPH038236A - Planer-type cold cathode - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electron source using a planar cold cathode.Prior art: Many thin-film field emission cold cathodes have been reported in the past. A planar cold cathode as shown in FIG. 4 (FIG. 5 of JP-A No. 63-274047) 1. t, 8
Although it is said that electron emission occurs at a gate voltage of 0 V or more, this cold cathode may be constructed by having a cold cathode 2 and a gate electrode 3 facing each other on the surface of an insulating substrate 1 as shown in FIG. 4. Although a large number of convex portions 4 are formed on the end face of the cold cathode facing the cold cathode, the distance between the tips of the convex portions provided on the cold cathode and the gate electric field is 0.1 μm, but the configuration is as follows. When a voltage of 80V or more is applied between the cold cathode and the gate electrode, the radius of curvature of the tip of the convex part of the cold cathode is small, and a strong electric field of 2 x 10'V/cm is generated in the convex part, and electrons are ejected from the tip. Issues to be Solved by the Invention The planar cold cathode described above has the characteristics described above.
It is necessary to widen the distance between the cold cathode and the gate electrode to about 2 to 4 μm. In order to meet these conditions, a convex portion of the cold cathode with a smaller radius of curvature is required. Current photoetching technology has a limit in strength.

In addition, if impurities are attached to the electrode surface or an oxide film is formed during the manufacturing process of the planar cold cathode, the work function of the electrode surface changes, causing a problem in which the electron emission start voltage varies between elements. Means for Solving the Problems In a planar cold cathode composed of two pairs of electrodes formed on the surface of an insulating substrate, the tip of the cold cathode is formed with a wall opening L between the walls.

By forming a wall opening at the tip of the working cold cathode, an edge with a very small radius of curvature is formed at the edge of the wall opening, and a strong electric field is generated at the edge, which is different from the conventional configuration. Compared to a planar cold cathode, it is possible to operate at a lower voltage, and a clean metal surface appears on the wall opening.The work function of the electron emitting part at the tip of the cold cathode is made uniform, and the electron emission starting voltage is A planar cold cathode with uniform and stable properties between elements can be obtained.

Examples Example 1 FIG. 1 shows the main part of the electrode structure of Example 1. The 1-0 electrode includes a cold cathode 8 having a wall opening 7 on the surface of an insulating layer 6 formed on the surface of a substrate 5, and a gate. The electrodes 9 are arranged to face each other on parallel flat plates.

The manufacturing process of this planar cold cathode is shown in FIG.

After forming an SiO2 film 6 with a thickness of 1 μm as an insulating layer on the surface of the Si wafer substrate 5 by thermal oxidation, a WS2 film 7 with a thickness of 082 μm is formed on the surface of this SiO=film 6 (FIG. 2a). A cold cathode 8 and a gate electrode 9 are simultaneously formed on this WSi2 film 7 by photo-etching, and the distance between the cold cathode and the gate electrode is 1 to 4 μm (FIG. 2b).

Next, this substrate was etched with a buffer etch solution (HFI and NH,
The S i 02 film 6 is etched by immersing the cold cathode in a mixed solution (F6 volume) to form a recess 10 at the bottom of the cold cathode tip, making the cold cathode tip shaped like an eaves (FIG. 2C). Further, this substrate was immersed in fluoronitric acid, and the eaves-like portion of the cold cathode 8 was etched from above and below to form a cold cathode having a tip 11 with a thickness of 200 to 1000 mm (FIG. 2d). The cold cathode tip 11 having the eave-like tip shape formed in this manner is subjected to ultrasonic waves to form a cold cathode having an open wall surface 12 (FIG. 2e).

Combination of electrode material and insulating material; L W S i 2
and 5102, and W as an electrode material.
.

It is possible to combine materials such as MO, W2C, NbC, and HfC with high melting and low ζ work functions that are hardly soluble in buffer etch solutions, and materials that dissolve in buffer etch solutions such as glass plates as insulator substrate materials. When a voltage of 50 to 70 V is applied between the cold cathode configured in this way and the gate electrode, a strong electric field of IO'V/cm or more is generated at the edge of the open surface of the cold cathode tip wall, and electrons are emitted from the tip. happen.

In the configuration of this embodiment, the variation level of the electron emission starting voltage can be suppressed to about IOV, which was about 30V in the conventional structure.

Example 2 FIG. 3 shows the main part of the electrode structure of Example 2. The intussusception is formed by a double layer of conductive material 13 and cold cathode material 14.

We will explain the manufacturing method of this planar cold cathode &Si
A thermally oxidized 5102 insulating layer 16 is formed on the substrate 15, a WSi2 film 13 with a thickness of 0.2 μm is formed on this surface, and a WC film 14 with a thickness of 500 μm is laminated on this surface.
Si2. Although the cold cathode section 17 and the gate electrode section 18 are formed simultaneously on the WC double layer by photoetching, the distance between the cold cathode and the gate electrode is 1 to 4 .mu.m. Next, this substrate is immersed in a buffer etch solution to etch the insulating layer 16 to form a recess 19 at the bottom of the cold cathode tip.L-The cold cathode tip is shaped like an eave. Furthermore, this substrate is immersed in fluorinated nitric acid, and only the WSi2 film 13 at the bottom of the tip of the electrode double layer is removed by etching, thereby forming a cold cathode having a 500 mm thick WC tip. The cold cathode tip having the formed eave-like tip shape is subjected to ultrasonic waves to form a cold cathode having an inter-wall L and a wall opening 20.

The conductive material 13 serves to reduce the resistance of the protective gate electrode and wiring, and to increase the adhesive strength between the cold cathode material and the substrate material.

The combination of the conductive material of the electrode double layer and the cold cathode material is W.
Not limited to Si2 and WC, conductive materials such as W, MO, W2C, NbC, HfC\dissolved in fluoronitric acid, materials poorly soluble in buffer etch solution, and cold cathode materials include WC and SiC.

Combinations of low work function materials that are sparingly soluble in Ta, B4CR fluoronitric acid, and buffered etch solutions are possible.

Furthermore, any material that is sparingly soluble in solutions for etching substrate materials and acidic and alkaline solutions for etching conductive materials and has a relatively low work function can be used as a cold cathode material. In addition, conductive materials include acids other than fluoro-nitric acid, metal materials that dissolve in alkaline solutions, and Au.
Alloy materials such as Cr can be used. Further (mi)
If necessary, the electrode can be configured with a double layer or more.

50 to 60 mm between the cold cathode and the gate electrode configured in this way.
When a voltage of V is applied, a voltage of 10'V/cm is applied to the cold cathode tip.
Effects of the Invention According to the present invention, by forming a wall opening at the cold cathode tip, electron emission occurs at a low voltage of 100 V or less. A stable electron source with uniform starting voltage between elements can be obtained.

[Brief explanation of the drawing]

Figure 1: A perspective view of a planar cold cathode according to an embodiment of the present invention Figure 2: A cross section of a plate for explaining the manufacturing process of a planar cold cathode according to an embodiment of the present invention A cross section of a planar cold cathode according to another embodiment of the present invention is shown in FIG. 4 (a perspective view of a conventional planar cold cathode).
Cold cathode 3,9.18...Gate heavy state 4...Cold cathode tip 5,15...S1 wafer substrate, 6,16
...Insulating layer 10, 19...Insulating layer recess 11...
・Cold cathode tip 7, 12, 20 ・Wall partition 13...
Conductive material, 14...cold cathode material tag

Claims (4)

[Claims] (1) A planar cold cathode consisting of two pairs of electrodes formed on the surface of an insulating substrate, characterized in that a wall opening is formed in at least a part of the cold cathode tip. Planar cold cathode. (2) The distance between the cold cathode tip and the opposing gate electrode is 0
．． The planar cold cathode according to claim 1, characterized in that the thickness is 3 μm or more and 5 μm or less. (3) The planar cold cathode according to claim 1 or 2, characterized in that a recess is provided on the surface of the insulator substrate between the cold cathode and the gate electrode. (4) After forming a cold cathode material on the surface of the insulator substrate to form a cold cathode and a gate electrode, etching the surface of the insulator substrate to form an eaves-shaped cold cathode; The planar cold cathode according to any one of claims 1 to 3 is formed by etching the cold cathode to a thickness of 0.1 μm or less and opening the eaves-like portion of the cold cathode. A method for manufacturing a planar cold cathode.