JPH0765706A - Cathode device and its manufacture - Google Patents

Abstract

PURPOSE:To cause electric field emission with the lowest possible voltage, concerning a cathode device and its manufacture. CONSTITUTION:This is equipped with a substrate 1, at least one emitter tip 2, which has a conical head 2A, and a gate electrode layer 4, which has an opening 4A to expose the head of that emitter tip 2, and the diameter of that opening 4A of that gate electrode layer is smaller than the diameter of the junction with that substrate of that emitter tip 2. In the manufacture, this is so arranged that the gate electrode material of the gate electrode layer 4 is stuck to the diffusion film on the surface of the conical head of the emitter tip 2, and that the inside periphery wall of the opening of the gate electrode layer 4 extends nearly parallel with the conical head of the emitter tip by the removal of that diffusion film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode device, and more particularly to a cathode device called a minute field emission cold cathode. The invention further relates to a method of manufacturing a cathode device using etching.

[0002]

2. Description of the Related Art As shown in FIG. 28, for example, a micro field emission cold cathode comprises an emitter tip 2 having one or more conical tip portions formed on a substrate 1, and a substrate 1.
And a gate electrode layer 4 having an opening for exposing the tip portion of the emitter tip 2. The insulating layer 3 is provided between the substrate 1 and the gate insulating layer 4.
By applying a voltage between the base end portion 2B of the emitter tip 2 and the gate electrode layer 4, the tip end portion 2A of the emitter tip 2 and the inner peripheral wall 4 of the opening portion 4A of the gate electrode layer 4.
A strong electric field is generated between B and B, and electrons are emitted from the tip portion of the emitter tip.

The minute field emission cold cathode is an electron emission source and is used as a display device, a micro vacuum tube, or the like. Further, the minute field emission cold cathode is characterized in that it can operate at high speed because of its high electron mobility, and has high resistance to high temperature operation and radiation damage. Therefore, the micro field emission cold cathode is not only used in the above-mentioned applications, but also in the fields of microwave devices, ultra-high speed operation devices, active devices used in the radiant environment such as space and nuclear reactors, active devices used in high temperature environments, etc. Is expected to be used.

It is known to form such a cathode device using etching. For example, in FIG. 29, when the silicon substrate 1 is used and a mask 51 corresponding to the diameter of the emitter tip 2 is formed on the substrate 1 (A) and etching is performed, a portion of the substrate 1 not covered by the mask 51 is formed. The surface of the substrate is scraped, and the lower part of the mask on the substrate remains in a mountain shape (B). This mountain part is the emitter tip 2
Becomes Then, when the substrate 1 is subjected to thermal oxidation treatment with the mask 51 left, the oxide diffuses inside the emitter tip, and an oxide film 52 is formed on the surface of the emitter tip 2 (C). By removing the oxide film 52, the emitter tip 2 having a sharp tip is formed.

Then, the substrate insulating layer 3 was formed while leaving the mask 51. Since there is a mask 51 on the emitter tip 2, the insulating layer 3 is the mask 5 on the substrate 1.
It is formed on the portion not covered with 1 and on the mask 51. Then, the gate electrode layer 4 is formed on the insulating layer 3 by vapor deposition or the like. The gate electrode layer 4 is formed on the insulating layer 3 on the substrate 1 and on the mask 51.
Formed on. Therefore, if the mask 51 is removed,
The insulating layer 3 and the gate electrode layer 4 on the mask 51 are simultaneously removed. Therefore, openings are formed in the insulating layer 3 and the gate electrode layer 4 on the substrate corresponding to the mask 51 thus removed, and the emitter tip 2 is exposed as shown in FIG.

In the cathode device manufactured as described above, the junction (bottom surface) of the emitter tip 2 with the substrate 1 is joined.
Is smaller than the size of the mask 51. The size d of the opening 4A of the gate electrode layer 4 is determined by the mask 5
Depends on the size of 1. Therefore, (D <d).
Actually, as shown in FIG. 30, when the insulating layer 3 is formed by vapor deposition, the contour shape of the insulating layer 3 on the mask 51 tends to widen upward, and the step shape of the emitter tip may be increased. There may be a collared growth portion 10. In the subsequent formation of the gate electrode layer 4, the size of the opening 4A of the gate electrode layer 4 becomes larger than that of the mask 51. As shown in FIG. 31, when the mask 51 and the insulating layer 3 thereon and the collar-shaped growth portion 10 are removed,
The size D with the emitter tip is smaller than the size d of the opening 4A of the gate electrode layer 4. In addition, the size of the mask is, for example, 1 according to the current photolithography technology.
It cannot be less than about μm.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a cathode device capable of causing field emission at a voltage as low as possible and a method for manufacturing the same.

[0008]

A cathode device according to the present invention comprises a substrate 1 and a conical tip portion 2 formed on the substrate.
And at least one emitter tip 2 having A, and a gate electrode layer 4 having an opening 4A formed above the substrate and exposing a tip portion of the emitter tip, the opening 4A of the gate electrode layer. Is smaller than the diameter of the junction of the emitter tip 2 with the substrate. The present invention also provides a display device including such a cathode device.

Further, a method of manufacturing a cathode device suitable for manufacturing the above-mentioned cathode device includes a step of forming at least one emitter tip having a conical tip portion on a substrate, and a surface of the formed emitter tip. A step of forming an oxide film on the surface of the emitter tip, and a gate electrode material is attached to the oxide film on the surface of the conical tip portion of the emitter tip at least, and has an opening 4A exposing the tip portion of the emitter tip. Thus, the step of forming the gate electrode layer 4 and the step of removing the oxide film on the surface of the emitter tip are performed. By removing the oxide film, the inner peripheral wall of the opening of the gate electrode layer is removed. It is characterized in that it is formed outside the conical tip portion so as to extend substantially parallel to the tip portion.

[0010]

In the cathode device according to the present invention, since the diameter of the opening of the gate electrode layer is smaller than the diameter of the junction of the emitter tip with the substrate, the tip of the emitter tip is within the opening of the gate electrode layer. It becomes closer to the peripheral wall, and it becomes possible to cause field emission at a voltage much lower than the conventional one. In the method for manufacturing a cathode device according to the present invention, the inner peripheral wall of the opening of the gate electrode layer is formed outside the conical tip portion of the emitter tip in a substantially frustoconical shape extending substantially parallel to the tip portion. Therefore, the diameter of the opening of the gate electrode layer can be made smaller than the diameter of the base end of the emitter tip. Therefore, it is possible to obtain a cathode device capable of causing field emission at a considerably low voltage.

With the advance of such a cathode device, it is required to cause field emission at a voltage as low as possible. In order to generate field emission at a voltage as low as possible, the size of the opening in the gate electrode layer where the emitter tip is exposed should be made as small as possible, and the inner peripheral wall of the opening in the gate electrode layer should be as close as possible to the emitter tip. The inventors have found that it is desirable. Furthermore, the present inventors have found that it is preferable to make the height of the inner peripheral wall of the opening of the gate electrode layer as high as possible and increase the area surrounding the tip portion of the emitter tip.

[0012]

1 is a diagram showing a cathode device 100 according to the present invention. The cathode device 100 includes a substrate 1, an emitter tip 2 formed on the substrate 1, an insulating layer 3, and a gate electrode layer 4. An oxide film 52 is formed between the substrate 1 and the insulating layer 3. The emitter tip 2 includes a conical tip portion 2A and a cylindrical base portion 2B. However, the emitter tip 2 is a cylindrical base end portion 2
It is also possible to adopt a structure in which B is not included and only the substantially conical tip portion 2A is provided. Insulating layer 3 and gate electrode layer 4
Respectively have aligned openings 3A, 4A exposing the emitter tips 2. Opening 4A of the gate electrode layer 4
The inner peripheral wall 4B of the emitter tip 2 surrounds the tip portion 2A of the emitter tip 2, and a strong electric field is generated between the tip portion 2A of the emitter tip 2 and the inner peripheral wall 4B of the opening 4A of the gate electrode layer 4, and the tip of the emitter tip 2 is Electrons are emitted from the portion 2A. A cathode electrode (not shown) is connected to the base end portion 2B of the emitter tip 2.

In FIG. 1, the inner peripheral wall 4B of the opening 4A of the gate electrode layer 4 is formed outside the conical tip portion 2A of the emitter tip 2 in a substantially frustoconical shape extending substantially parallel to the tip portion 2A. To be done. Therefore, the gate electrode layer 4
The diameter of the inner peripheral wall 4B of the opening 4A of the
The diameter is smaller than the diameter at the joint portion (bottom portion) with the substrate 1. Inner peripheral wall 4 of opening 4A of gate electrode layer 4
The width of B (as viewed in the height direction of the emitter tip 2) is larger than the thickness (of the portion above the insulating layer 3) of the gate electrode layer 4.

FIG. 2 is a schematic diagram showing an example of using the cathode device 100 of FIG. In this example, the display substrate 1 is, for example, n
P-type region 1a of opposite conductivity type is formed on the surface of the n-type substrate 1. A plurality of emitter tips 2 are formed in each p-type region 1a. In this case, the p-type region 1a is used as a cathode electrode, and a certain p-type region 1a and the gate electrode layer 4 are used.
When a voltage is applied between the emitter and the emitter, an electron is emitted from the emitter tip 2 of the p-type region 1a as indicated by an arrow, and the emitted electron is flown to the anode device 200 provided in association with this cathode device. It is designed to go out.

FIG. 3 is a diagram showing an example in which the cathode device 100 of FIGS. 1 and 2 is used in a display device. p-type region 1a
The gate electrode layer 4 and the gate electrode layer 4 are arranged in a matrix with the insulating layer 3 interposed therebetween, and electrons can be ejected from the emitter tip 2 at a specific position on the matrix toward the anode device 200. On the other hand, in the anode device 200, an anode layer 201 is formed on a transparent plate, and a fluorescent layer (R, R,
G, B) 202 is provided. Therefore, the cathode device 100
The electrons that have come from a specific position hit the fluorescent layer 102 at a specific position and emit light. As a result, color display can be performed. The cathode device 100 is not limited to this example, but can be applied to various examples such as a micro vacuum tube as described above.

FIGS. 4 to 10 are views showing successive steps of the first embodiment of the manufacturing method for manufacturing the cathode device 100 of FIG. In FIG. 4, the Si substrate 1 is prepared.
The Si substrate 1 is of the n-type type as shown in FIG. 2, and the p-type region 1a is formed in advance on the surface thereof. Alternatively, the cathode electrode made of another conductor may be formed on the Si substrate 1.

Therefore, a layer serving as a mask for forming the emitter tip 2 is formed on the Si substrate 1 by, for example, a chemical vapor deposition (CVD) method. In an embodiment, this mask layer is, for example, a first layer of Si ₃ N ₄ having a thickness of 300 nm.
And a second insulating layer 51 of SiO ₂ having a thickness of 300 nm, for example. First insulating layer 6
1 is directly above the substrate 1 and the second insulating layer 51 is above the first insulating layer 61. Nitrides such as Si ₃ N ₄ are SiO
_It has the property of being more soluble in hot phosphoric acid than ₂ . However, if the entire thickness is properly selected, the mask layer may be only the insulating film 51 made of SiO _2, for example. In addition,
In other embodiments, such a two layer structure may be particularly advantageous.

In FIG. 5, the first and second insulating layers 6
After exposing 1 and 51 by a known exposure means, the first and second insulating layers 61 and 51 are etched to form a mask pattern corresponding to the shape of the emitter tip 2. This etching uses CF ₄ as an etching gas,
Apply the RIE method.

In FIG. 6, the Si substrate 1 is etched using the masks 61 and 51 to form the emitter tip 2. In this case, SF ₆ is used as the etching gas and the RIE method is applied. Substrate 1 by etching
The surface of the part not covered with the mask of
The lower part of the mask remains as a chevron, and the remaining chevron-shaped part becomes the emitter tip 2.

The emitter tip 2 has a conical tip portion 2
In order to obtain a comparatively long shape consisting of A and a cylindrical base end portion 2B, in the embodiment, first, near isotropic etching is performed to form the conical tip portion 2A. Then, anisotropic etching is continuously performed to form a substantially cylindrical base end portion 2B. If the RIE method is used, the etching characteristics such as isotropic etching and anisotropic etching can be controlled and performed by selecting etching conditions such as pressure.

In FIG. 7, a thermal oxidation method is applied to form an oxide film 52 made of SiO ₂ on the exposed Si substrate 1. The oxide film 52 has an oxide of Si.
It is formed by diffusing into the inside of the substrate 1 and the emitter tip 2, and diffuses more into the inside than the surface of the Si substrate 1 and the surface of the emitter tip 2 at the stage of FIG. When the oxide film 52 is removed, the emitter tip 2 becomes sharper.

The oxide film 52 is also formed on the Si substrate 1 at the stage of FIG.
Of the emitter tip 2 and the surface shape of the emitter tip 2. Therefore, in a stage where the masks 61 and 51 are not removed, the outer shape of the oxide film 52 of the cylindrical base end portion 2B of the emitter tip 2 becomes slightly larger than the outer shapes of the masks 61 and 51 (of the masks 61 and 51). The extension of the outline is shown in broken lines in FIG. 7). That is, the shoulder portion of the oxide film 52 on the cylindrical base end portion 2B of the emitter tip 2 protrudes outside the outer contours of the masks 61 and 51.

In FIG. 8, the insulating layer 3 made of, for example, SiO _{2 having a} thickness of 1000 nm is formed by applying the vacuum deposition method. At this time, the contour shape of the insulating layer 3 on the masks 61 and 51 spreads outward in the radial direction as it goes upward (as the thickness of the insulating layer 3 increases).
The contour shape of the insulating layer 3 on the oxide film 52 on the substrate 1 where there is no 1 also expands similarly.

Further, in the formation of the insulating layer 3, the material of the insulating layer 3 adheres to the shoulder portion of the oxide film 52 on the cylindrical base end portion 2B of the emitter tip 2 and the collar-shaped growth portion 10 is formed. It is formed parasitically. The collar-shaped growth portion 10 is an oxide film 2B on the cylindrical base end portion 2B of the emitter tip 2.
Because the masks 61 and 51 protrude outside the outer shapes of the masks 61 and 51. Therefore, as will be seen in a later example, the collar-shaped growth portion 10 may not be formed in the formation of the insulating layer 3.

In FIG. 9, the gate electrode layer 4 made of Cr, for example, having a thickness of 200 nm is formed by applying the vacuum deposition method. In this embodiment, the presence of the collar-shaped growth portion 10 is positively utilized in the step of forming the gate electrode layer 4. That is, the gate electrode material is used as a saucer so that the gate electrode material is more adhered to the oxide film 52 on the conical tip portion 2A of the emitter tip 2 by using the gate electrode material as the saucer.
To pass near the oxide film 52 on the tip portion 2A of the emitter tip 2.

Furthermore, in the step of forming the gate electrode layer 4, oblique vapor deposition is preferably performed. That is, while rotating the substrate 1 around its central axis (rotational axis), the gate electrode material is vapor-deposited on the substrate 1 from an oblique direction (arrow A) with respect to the rotational axis. As a result, the gate electrode material passes over the collar-shaped growth portion 10 and reaches the oxide film 52 on the tip portion 2A of the emitter tip 2 more, and the oxide film 5
Attach to 2.

Further, in the step of forming the gate electrode layer 4, instead of the vacuum evaporation method, a sputtering method or a CVD method is used.
You can use the law. In these methods,
The gate electrode material easily wraps around the collar-shaped growth portion 10 to the vicinity of the oxide film 52 on the tip portion 2A of the emitter tip 2 and the gate electrode material easily adheres to the oxide film 52. Furthermore, it is possible to select a processing condition in which the gate electrode material easily wraps around. For example, in the case of the sputtering method, the film formation pressure is raised from the standard 5 mtorr to 20 mtorr, or the distance between the substrate 1 and the target is set to a normal 12 mtorr.
A method such as narrowing it from 0 mm to 70 mm and increasing the solid angle of the target seen from the substrate 1 is effective. Further, as the film thickness is increased, the amount of gate electrode material attached to the oxide film 52 increases.

Then, as shown in FIG. 10, the masks 61 and 51, the oxide film 52 on the surface of the conical tip portion 2A of the emitter tip 2 and the collar-shaped growth portion 10 are removed. In the example, the substrate 1 was immersed in a hydrofluoric acid etchant to dissolve these portions. Due to the dissolution of the oxide film 52, a sharp emitter tip 2 appears,
The insulating layer 3 and the gate electrode layer 4 are provided with openings 3A and 4A exposing the emitter tip 2, respectively.

Then, the gate electrode layer 4 is formed in an appropriate pattern (see FIG. 3) by applying wet etching. The cathode device 100 of FIG. 10 is the same as the cathode device of FIG. In FIG. 10, the diameter of the inner peripheral wall 4B of the opening 4A of the gate electrode layer 4 is indicated by d, and the diameter of the junction of the emitter tip 2 with the substrate 1 is indicated by D. In the present invention, d <D. Further, the width W of the inner peripheral wall 4B of the opening 4A of the gate electrode layer 4 is larger than the thickness t of the gate electrode layer 4.

FIG. 11 is a diagram showing the results of measuring the relationship between voltage and current of the cathode device of the present invention and the conventional cathode device. The horizontal axis represents voltage and the vertical axis represents emission current.
The circles indicate the present invention, and the squares indicate the prior art. In the measurement, 6400 cathode devices are arranged and operated, and the measurement results are shown. As can be seen, the cathode device according to the invention has a rapid start of emission at a lower voltage compared to the prior art device.

FIG. 12 is a diagram showing the characteristics of field emission according to the Fowler-Nordheim formula, in which the horizontal axis represents 1000 / V and the vertical axis represents I / V. The characteristics based on field emission are as follows.
According to Nordheim's formula, if you take logarithms on both sides,
If it becomes a straight line, it can be regarded as field emission.

Je = Aexp (Bφ ^3/2 ) where Je is the current density, φ is the work function, and A and B are constants. This data also shows the measurement results obtained by arranging and operating 6400 cathode devices, and the circles indicate the present invention, and the squares indicate the prior art.

In this figure, it is known that the characteristic line has a small inclination and that the characteristic line is located above. As can be seen, the cathode device according to the invention shows that a higher current is obtained at a lower voltage compared to the prior art.

FIG. 13 is a diagram showing the relationship between the height of the emitter tip 2 and the electric field multiplication factor. Each curve P, Q, R
Is the total thickness of the oxide film 52 and the insulating layer 3 of FIG.
m and the inner peripheral wall 4 of the opening 4A of the gate electrode layer 4
The electric field multiplication factors when the width W of B is 0.2, 0.4, and 0.6 μm are shown. In each of the curves P, Q, and R, the electric field multiplication factor is such that the height of the emitter tip 2 is about 1.
It is shown that a peak occurs at 41 μm. Further, it is shown that the electric field multiplication coefficient becomes higher (curve R> curve Q> curve P) as the width W of the inner peripheral wall 4B increases. Therefore, according to the present invention, the opening 4 of the gate electrode layer 4 is formed.
The inner peripheral wall 4B of A is formed into a substantially frustoconical shape that extends substantially parallel to the conical tip portion 2A of the emitter tip 2, and thus the width W of the inner peripheral wall 4B can be increased, thereby increasing the electric field multiplication factor. be able to.

14 to 17 are views showing successive steps of the second embodiment of the manufacturing method for manufacturing the cathode device 100. The same steps as those of FIGS. 4 to 7 of the previous embodiment are also adopted in the second embodiment, and FIG. 14 shows the same state as that of FIG. 8 of the previous embodiment. That is, FIG.
Form masks 61 and 51 for forming the emitter tip 2 on the Si substrate 1, pattern the masks 61 and 51, and etch the Si substrate 1 using the masks 61 and 51 to form the emitter tip 2 Formed and Si substrate 1
2 shows a state in which an oxide film 52 is formed on the surface of the emitter tip 2 and the surface of the emitter tip 2 and the insulating layer 3 is formed. Further, at the same time when the insulating layer 3 is formed, the collar-shaped growth portion 10
Are formed parasitically.

In this embodiment, as shown in FIG. 15, after forming the insulating layer 3, the substrate 1 is immersed in an etchant made of hot phosphoric acid. Since nitrides such as Si ₃ N ₄ are more easily dissolved in hot phosphoric acid than SiO ₂ , the first insulating layer 61 of the mask is easily dissolved and removed from the substrate 1, and at the same time the second insulating layer of the mask is removed. Layer 51 is also removed. On the other hand, the insulating layer 3 and the collar-shaped growth portion 10 remain without being melted.

In FIG. 16, the gate electrode layer 4 made of, for example, 200 nm of Cr is formed by applying the vacuum evaporation method. In this case, since the masks 61 and 51 are not provided, the gate electrode layer 4 adheres to the oxide film 52 on the collar-shaped growth portion 10 and the tip portion 2A of the emitter tip 2 and grows while gradually increasing in size.

In FIG. 17, the substrate 1 is dipped in a hydrofluoric acid etchant to remove the oxide film 52 and the collar-shaped growth portion 10 covering the emitter tip 2. The etchant penetrates into the gap formed at the edge of the gate electrode material at the upper end of the oxide film 52 of the tip portion 2A of the emitter tip 2 or the gate electrode material that is thinned in the gap shape, so that the oxide film 52 and the like are removed. It Note that, as shown in FIG. 26 corresponding to FIG. 6, for example, in the etching process of the substrate 1, if the RIE conditions are appropriately set so that the tip 2A of the emitter tip 2 has a constriction 2C, FIG. As shown in FIG. 27 corresponding to, the gap 4G of the gate electrode layer 4 can be increased, and the removal of the oxide film 52 of FIG. 17 becomes easier. When the oxide film 52 and the collar-shaped growth portion 10 are removed in this manner, the opening 4A of the gate electrode layer 4 and the opening 3A of the insulating layer 3 are formed around the tip portion 2A of the emitter tip 2. To be done. The opening diameter of the gate opening 4A generated by the second embodiment is the same as that of the gate opening 4 of the previous embodiment.
It can be made smaller than the opening diameter A.

FIG. 18 is a diagram showing a third embodiment of the manufacturing method for manufacturing the cathode device 100. (A) is S
Mask 6 for forming emitter tip 2 on i substrate 1
1 and 51 are formed, the masks 61 and 51 are patterned, the Si substrate 1 is etched using the masks 61 and 51 to form the emitter tip 2, and the insulating layer 3 is formed. In this embodiment, the insulating layer 3 is formed before the oxide film 52. The emitter tip 2 is relatively short and is composed only of a substantially conical tip portion 2A. In this case, the proximal end portion 2 described in the previous embodiment
Since there is no B shoulder, the collar growth 10 is not parasitically formed.

In (B), after forming the insulating layer 3, the substrate 1 is immersed in an etchant made of hot phosphoric acid. Also in this case, since nitrides such as Si ₃ N ₄ are easier to dissolve than SiO ₂ , the masks 61 and 51 are removed from the substrate 1 and the insulating layer 3 remains undissolved.

In (C), in order to sharpen the emitter tip 2, an oxide film 52 is formed on the surface of the Si substrate 1 and the surface of the emitter tip 2. In (D), the gate electrode layer 4 is formed. In this case, since the masks 61 and 51 and the collar-shaped growth portion 10 are not provided, the gate electrode layer 4 is sufficiently attached to the oxide film 52 on the tip portion 2A of the emitter tip 2.

In (E), the oxide film 52 covering the emitter tip 2 is removed with an etchant. The etchant penetrates into the gap of the gate electrode layer 4 formed at the edge of the upper end portion of the oxide film 52 of the tip portion 2A of the emitter tip 2 or the gate electrode material thinned in the gap shape, so that the oxide film 52 is removed. It Also in this case, as shown in FIG. 26, if a constriction 2C is formed in the tip portion 2A of the emitter tip 2, as shown in FIG. 27, the gap 4G of the gate electrode layer 4 is formed.
The oxide film 52 can be removed more easily. Also in this embodiment, the gate opening 4
The diameter of A is smaller than the diameter of the bottom surface of the emitter tip 2.

FIG. 19 is a view showing a fourth embodiment of the manufacturing method for manufacturing the cathode device 100. This embodiment is almost the same as the embodiment of FIG. (A) is the Si substrate 1
Masks 61 and 51 for forming the emitter tip 2 on the top
Is formed, the masks 61 and 51 are patterned, the Si substrate 1 is etched using the masks 61 and 51 to form the emitter tip 2, and the insulating layer 3 is formed. However, the emitter tip 2 includes a conical tip portion 2A and a cylindrical base portion 2B. However, since the oxide film 52 is not formed yet, the oxide film 5 is not formed.
Since there is no expansion of the shape associated with the formation of 2 and the shoulder portion of the base end portion 2B does not protrude beyond the masks 61 and 51, the collar-shaped growth portion 10 is not parasitically formed.

In (B), the substrate 1 is immersed in an etchant made of hot phosphoric acid to remove the masks 61 and 51 from the substrate 1. The insulating layer 3 remains undissolved. Then, in order to sharpen the emitter tip 2, the Si substrate 1
An oxide film 52 is formed on the surface of the emitter tip 2 and the surface of the emitter tip 2.

In (C), the gate electrode layer 4 is formed. In this case, since the masks 61 and 51 and the collar-shaped growth portion 10 are not provided, the gate electrode layer 4 is sufficiently attached to the oxide film 52 on the tip portion 2A of the emitter tip 2. . In (E), the oxide film 52 covering the emitter tip 2 is removed with an etchant. Also in this embodiment, the diameter of the gate opening 4A is smaller than the diameter of the bottom surface of the emitter tip 2.

FIG. 20 is a view showing a fifth embodiment of the manufacturing method for manufacturing the cathode device 100. (A) is Si
Mask 6 for forming emitter tip 2 on substrate 1
1 and 51 are formed, the masks 61 and 51 are patterned, and the Si substrate 1 is etched by using the masks 61 and 51 to form the emitter tip 2 and the emitter tip 2 is sharpened. 2 shows a state in which an oxide film 52 is formed on the surface of the and the tip of the emitter tip 2. In this embodiment, the emitter tip 2 is relatively short and comprises only a substantially conical tip portion 2A.

In (B), the insulating layer 3 is formed after the oxide film 52 is formed. In this case, the collar-shaped growth portion 10 is not parasitically formed because the shoulder portion of the proximal end portion 2B described in the previous embodiment is not provided. In (C), the substrate 1 is immersed in an etchant made of hot phosphoric acid, and the masks 61 and 51 are removed. The insulating layer 3 remains undissolved.

In (D), the gate electrode layer 4 is formed. Also in this case, since the masks 61 and 51 and the collar-shaped growth portion 10 are not provided, the gate electrode layer 4 is sufficiently attached to the oxide film 52 on the tip portion 2A of the emitter tip 2.
In (E), the oxide film 52 covering the emitter tip 2 is removed with an etchant. The etchant penetrates into the gap of the gate electrode material formed at the edge of the upper end portion of the oxide film 52 of the tip portion 2A of the emitter tip 2 or the gate electrode material thinned like a gap, and thus the oxide film 52 is removed. . Also in this case, as shown in FIG. 26, if the tip portion 2A of the emitter tip 2 is allowed to have a constriction 2C, the gap 4G of the gate electrode layer 4 should be increased as shown in FIG. Therefore, the oxide film 52 can be removed more easily. Also in this embodiment, the diameter of the gate opening 4A is smaller than the diameter of the bottom surface of the emitter tip 2.

FIG. 21 is a view showing a sixth embodiment of the manufacturing method for manufacturing the cathode device 100. This embodiment is almost the same as the embodiment of FIG. (A) shows masks 61, 5 for forming the emitter tip 2 on the Si substrate 1.
1 is formed, the same masks 61 and 51 are patterned, the Si substrate 1 is etched using the masks 61 and 51 to form the emitter tip 2, and the emitter tip 2 is sharpened. In addition, the oxide film 52 is formed on the surface of the emitter tip 2 and the insulating layer 3 is formed. In this embodiment, the emitter tip 2 comprises a conical tip portion 2A and a cylindrical base portion 2B, and a collar-shaped growth portion 10 is parasitically formed.

In (B), the substrate 1 is immersed in an etchant made of hot phosphoric acid to remove the masks 61 and 51. Etching is performed so that the insulating layer 3 is not dissolved but the collar-shaped growth portion 10 is dissolved. Then, the gate electrode layer 4 is formed. Also in this case, since the masks 61 and 51 and the collar-shaped growth portion 10 are not provided, the gate electrode layer 4 is sufficiently attached to the oxide film 52 on the tip portion 2A of the emitter tip 2.

In (C), the oxide film 52 covering the emitter tip 2 is removed with an etchant. Also in this embodiment, the diameter of the gate opening 4A is smaller than the diameter of the bottom surface of the emitter tip 2.

FIG. 22 is a view showing a seventh embodiment of the manufacturing method for manufacturing the cathode device 100. (A) is Si
Mask 6 for forming emitter tip 2 on substrate 1
1 and 51 are formed, the masks 61 and 51 are patterned, and the Si substrate 1 is etched using the masks 61 and 51 to form the emitter tip 2.

In (B), the substrate 1 is dipped in an etchant made of hot phosphoric acid or hydrofluoric acid to remove the masks 61 and 51, and then the Si substrate 1 is sharpened to sharpen the emitter tip 2. An oxide film 52 is formed on the surface of the emitter tip 2 and the surface of the emitter tip 2. Emitter tip 2
Consists of a substantially conical tip portion 2A. In addition,
In this case, the mask may be a single layer film made of only SiO ₂ 51.
In (C), the gate electrode layer 4 is formed after forming the oxide film 52. Also in this case, the masks 61, 51
Since there is no collar-shaped growth portion 10, the gate electrode layer 4 adheres sufficiently to the oxide film 52 on the tip portion 2A of the emitter tip 2.

In (D), the oxide film 52 covering the emitter tip 2 is removed with an etchant. The etchant penetrates into the gap of the gate electrode material formed at the edge of the upper end portion of the oxide film 52 of the tip portion 2A of the emitter tip 2 or the gate electrode material thinned like a gap, and thus the oxide film 52 is removed. . Also in this case, as shown in FIG. 26, if a constriction 2C is formed in the tip portion 2A of the emitter tip 2, as shown in FIG. 27, the gap 4G of the gate electrode layer 4 is formed.
The oxide film 52 can be removed more easily. However, the oxide film 52 is formed on the surface of the substrate 1 other than the region where the emitter tip 2 is arranged.
Remains undissolved and becomes an insulating layer between the substrate 1 and the gate electrode layer 4. Also in this embodiment, the gate opening 4A
Is smaller than the diameter of the bottom surface of the emitter tip 2.

FIG. 23 is a diagram showing an eighth embodiment of the manufacturing method for manufacturing the cathode device 100. This embodiment is almost the same as the embodiment of FIG. (A) shows masks 61, 5 for forming the emitter tip 2 on the Si substrate 1.
1 is formed, the same masks 61 and 51 are patterned, the Si substrate 1 is etched using the masks 61 and 51 to form the emitter tip 2, and the emitter tips 2 are formed after the masks 61 and 51 are removed. Si for sharpening
It shows a state in which an oxide film 52 is formed on the surface of the substrate 1 and the surface of the emitter tip 2.

In (B), after forming the oxide film 52 and further forming the insulating layer 3, the gate electrode layer 4 is formed.
To form. In (C), the oxide film 52 covering the emitter tip 2 and part of the insulating layer 3 are removed by an etchant. Also in this embodiment, the gate opening 4
The diameter of A is smaller than the diameter of the bottom surface of the emitter tip 2.

FIG. 24 is a view showing a ninth embodiment of the manufacturing method for manufacturing the cathode device 100. This example
22 is substantially the same as the embodiment shown in FIG. 22, except that the emitter tip 2 is composed of a conical tip portion 2A and a cylindrical base portion 2B. That is, in (A), the Si substrate 1 is etched using a mask to form the emitter tip 2, and after removing the mask, the oxide film 52 is formed on the surface of the Si substrate 1 and the surface of the emitter tip 2. Form.

In (B), the gate electrode layer 4 is formed after the oxide film 52 is formed. In (C),
The oxide film 52 covering the emitter tip 2 is removed with an etchant. However, the oxide film 5 is formed on the surface of the substrate 1 other than the region where the emitter tip 2 is arranged.
2 remains undissolved and becomes an insulating layer between the substrate 1 and the gate electrode layer 4. Also in this embodiment, the gate opening 4
The diameter of A is smaller than the diameter of the bottom surface of the emitter tip 2.

FIG. 25 is a diagram showing a tenth embodiment of a manufacturing method for manufacturing the cathode device 100. This embodiment is substantially the same as the embodiment of FIG. 23 except that the emitter tip 2 is composed of a conical tip portion 2A and a cylindrical base portion 2B. That is, in (A), the Si substrate 1 is etched using a mask to remove the emitter tip 2
Then, after removing the mask, an oxide film 52 is formed on the surface of the Si substrate 1 and the surface of the emitter tip 2.

In (B), after forming the oxide film 52 and further forming the insulating layer 3, the gate electrode layer 4 is formed.
To form. In (C), the oxide film 52 covering the emitter tip 2 and part of the insulating layer 3 are removed by an etchant. Also in this embodiment, the gate opening 4
The diameter of A is smaller than the diameter of the bottom surface of the emitter tip 2.

[0061]

According to the present invention, since the diameter of the inner peripheral portion of the opening of the gate electrode layer is made smaller than the diameter of the junction of the emitter tip with the substrate, field emission can be caused at a low voltage. Can obtain a cathode device that can
Thereby, a fine display device or the like can be configured. Moreover, since the gate electrode layer can be disposed closer to the tip portion of the emitter tip, the effect of electric field concentration is significantly improved, and the voltage for operating the minute field emission cold cathode can be lowered. .

[Brief description of drawings]

FIG. 1 is a sectional view showing a cathode device according to an embodiment of the present invention.

2 is a schematic diagram showing an example of using the cathode device of FIG. 1. FIG.

FIG. 3 is a schematic perspective view of a display device using the cathode device of FIG.

FIG. 4 is a diagram showing a step of the first embodiment of the method for manufacturing a cathode device according to the present invention.

FIG. 5 is a diagram showing a step subsequent to that in FIG.

FIG. 6 is a diagram showing a step subsequent to that in FIG.

FIG. 7 is a diagram showing a step subsequent to that in FIG.

FIG. 8 is a diagram showing a step subsequent to that in FIG. 7.

FIG. 9 is a diagram showing a step subsequent to that in FIG.

FIG. 10 is a diagram showing a step subsequent to that in FIG.

FIG. 11 is a diagram showing the relationship between voltage and current in cathode devices of the present invention and the prior art.

FIG. 12 is a diagram showing field emission characteristics of the cathode device of the present invention and the prior art.

FIG. 13 is a diagram showing the relationship between the height of an emitter tip and the thickness of a gate electrode.

FIG. 14 is a diagram showing a step of the second embodiment of the method for manufacturing the cathode device according to the present invention.

FIG. 15 is a diagram showing a step subsequent to that in FIG.

FIG. 16 is a diagram showing a step subsequent to that in FIG.

FIG. 17 is a diagram showing a step subsequent to that in FIG.

FIG. 18 is a diagram showing a third embodiment of the method of manufacturing a cathode device according to the present invention.

FIG. 19 is a diagram showing a fourth embodiment of the method of manufacturing the cathode device according to the present invention.

FIG. 20 is a view showing a fifth embodiment of the method of manufacturing the cathode device according to the present invention.

FIG. 21 is a diagram showing a sixth embodiment of the method of manufacturing the cathode device according to the present invention.

FIG. 22 is a diagram showing a seventh embodiment of the method of manufacturing the cathode device according to the present invention.

FIG. 23 is a diagram showing an eighth embodiment of the method of manufacturing the cathode device according to the present invention.

FIG. 24 is a view showing a ninth embodiment of the method of manufacturing the cathode device according to the present invention.

FIG. 25 is a diagram showing a tenth embodiment of a method for manufacturing a cathode device according to the present invention.

FIG. 26 is a diagram showing a modification of the etching process of FIG.

FIG. 27 is a diagram showing a modification of the gate electrode process of FIG.

FIG. 28 is a diagram showing a conventional cathode device.

FIG. 29 is a diagram showing a manufacturing process of a conventional cathode device.

FIG. 30 is a diagram showing another manufacturing process of the conventional cathode device.

31 is a view showing the conventional cathode device formed in FIG. 30. FIG.

[Explanation of symbols]

 1 ... Substrate 2 ... Emitter tip 3 ... Insulating layer 4 ... Gate electrode layer 52 ... Oxide film 51, 61 ... Mask

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadashi Nakatani 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (35)

[Claims] 1. A substrate (1), at least one emitter tip (2) formed on the substrate and having a conical tip portion (2A), and a tip of the emitter tip formed above the substrate. A gate electrode layer (4) having an opening (4A) exposing a portion thereof, the diameter of the opening (4A) of the gate electrode layer being the emitter tip (2).
A cathode device having a diameter smaller than a diameter of a junction with the substrate. 2. The cathode device according to claim 1, wherein the width of the inner peripheral wall of the opening of the gate electrode layer is larger than the thickness of the gate electrode layer. 3. The inner peripheral wall of the opening of the gate electrode layer is formed in a substantially frustoconical shape extending substantially parallel to the tip portion outside the conical tip portion of the emitter tip. The cathode device according to claim 2. 4. The cathode device according to claim 1, wherein there is an insulating layer between the substrate and the gate electrode layer, and the insulating layer has an opening exposing the emitter tip. 5. The cathode device according to claim 1, wherein an insulating layer is provided between the substrate and the gate electrode layer, and the insulating layer is made of an oxide film. 6. The cathode device according to claim 1, wherein the emitter tip has a substantially cylindrical base end portion between a junction with the substrate and the tip end portion. 7. The cathode device according to claim 1, wherein the emitter tip is formed in a substantially continuous conical shape from a joint portion with the substrate to the tip portion. 8. The cathode device according to claim 1, wherein a joint portion of the emitter tip with the substrate is electrically connected to a cathode electrode. 9. At least one having a conical tip portion.
A step of forming two emitter tips (2) on the substrate (1), and an oxide film (52) on the surface of the formed emitter tips.
And a gate electrode material is attached to at least the oxide film on the surface of the conical tip portion of the emitter tip and has an opening (4A) exposing the tip portion (2A) of the emitter tip. Forming the gate electrode layer (4) and removing the oxide film on the surface of the emitter tip. By removing the oxide film, the inner peripheral wall of the opening of the gate electrode layer is removed. A method of manufacturing a cathode device, wherein the emitter tip is formed outside the conical tip portion so as to extend substantially parallel to the tip portion. 10. The method of manufacturing a cathode device according to claim 9, further comprising forming an insulating layer having an opening exposing the emitter tip between the substrate and the gate electrode layer. . 11. The step of forming the insulating layer includes the formation of a collar-shaped growth portion that parasitically grows from an intermediate portion of the emitter tip, and the step of forming the gate electrode layer uses the collar-shaped growth portion as a mask. 11. The method of manufacturing a cathode device according to claim 10, wherein the gate electrode material is used so as to wrap around the collar-shaped growth portion and near the tip portion of the emitter tip. 12. In the step of forming the gate electrode layer, the inner peripheral wall of the opening of the gate electrode layer extends substantially parallel to the tip portion outside the conical tip portion of the emitter tip. The method for manufacturing a cathode device according to claim 9, wherein the cathode device is formed in a conical shape. 13. The step of forming the emitter tip includes the step of forming a mask corresponding to the shape of the emitter tip on the substrate, the step of etching the substrate using the mask, and the step of removing the mask. 10. The method for manufacturing a cathode device according to claim 9, wherein: 14. The mask is formed of at least a part of a material different from that of the oxide film, and in the step of removing the mask, the mask is selectively removed with respect to the oxide film. The method for manufacturing a cathode device according to claim 13. 15. The method of manufacturing a cathode device according to claim 14, wherein the step of removing the mask is performed after the step of forming the gate electrode layer. 16. The method of manufacturing a cathode device according to claim 14, wherein the step of removing the mask is performed before the step of forming the gate electrode layer. 17. The method for manufacturing a cathode device according to claim 9, wherein the oxide film forming step comprises a thermal oxidation treatment step. 18. In the oxide film forming step, an oxide film is formed on the surface of the emitter tip and the surface of the substrate, and the oxide film on the surface of the substrate is an insulating layer between the substrate and the gate electrode layer. It acts as the following.
7. The method for manufacturing a cathode device according to 7. 19. A step of forming an insulating layer between the substrate and the gate electrode layer separately from an oxide film on the surface of the substrate, wherein the step of forming the insulating layer is performed before the oxidation treatment. The method for manufacturing a cathode device according to claim 17, wherein 20. A step of forming an insulating layer between the substrate and the gate electrode layer separately from an oxide film on the surface of the substrate, the insulating layer forming step being performed after the oxidation treatment. The method of manufacturing a cathode device according to claim 17, wherein the method is a cathode device. 21. The step of forming the emitter tip includes the step of forming a mask corresponding to the shape of the emitter tip on the substrate, the step of etching the substrate using the mask, and the step of removing the mask. Including a step of forming an insulating layer having an opening exposing the emitter tip between the substrate and the gate electrode layer after the oxide film forming step and before the gate electrode layer forming step, the mask removal 10. The method for manufacturing a cathode device according to claim 9, wherein the step and the oxide film removing step are performed after the gate electrode layer forming step. 22. The step of forming the insulating layer includes forming a collar-shaped growth portion that parasitically grows from an intermediate portion of the emitter tip, and the collar-shaped growth portion is masked in the step of forming the gate electrode layer. Used as a gate electrode material so as to wrap around the tip of the emitter tip above the collared growth and, together with the oxide around the mask and the emitter tip after formation of the gate electrode layer. 22. Removing the collared growth portion.
A method for manufacturing the cathode device according to 1. 23. The step of forming the emitter tip comprises the step of forming a mask for the emitter tip on the substrate,
Including a step of etching the substrate using the mask, and a step of removing the mask, between the substrate and the gate electrode layer after the oxide film forming step and before the gate electrode layer forming step. A step of forming an insulating layer having an opening exposing the emitter tip, the mask removing step is performed after the insulating layer forming step and before the gate electrode layer forming step, and the oxide film removing step is performed. 10. The process according to claim 9, which is performed after forming the electrode layer.
A method for manufacturing the cathode device according to 1. 24. The step of forming the insulating layer includes forming a collar-shaped growth portion that parasitically grows from an intermediate portion of the emitter tip, and the step of forming the gate electrode layer masks the collar-shaped growth portion. Used as a gate electrode material so as to wrap around the tip of the emitter tip above the collared growth and, together with the oxide around the mask and the emitter tip after formation of the gate electrode layer. 24. Removing the collared growth portion.
A method for manufacturing the cathode device according to 1. 25. The step of forming the emitter tip comprises the step of forming a mask for the emitter tip on the substrate,
An opening for exposing the emitter tip between the substrate and the gate electrode layer before the oxide film forming step, the step including etching the substrate using the mask and removing the mask; Forming an insulating layer, the mask removing step is performed after the insulating layer forming step and before the oxide film forming step, and the gate electrode layer forming step is performed after the mask removing step. 10. The method for manufacturing a cathode device according to claim 9, wherein: 26. The step of forming an emitter tip comprises the step of forming a mask for the emitter tip on a substrate,
An etching step for etching the substrate using the mask and a step for removing the mask, and an opening for exposing the emitter tip is provided between the substrate and the gate electrode layer after the oxide film forming step. 10. The method of manufacturing a cathode device according to claim 9, further comprising the step of forming the insulating layer, the mask removing step being performed after the insulating layer forming step. 27. The step of forming the insulating layer includes forming a collar-shaped growth portion that parasitically grows from an intermediate portion of the emitter tip, and the step of forming the gate electrode layer masks the collar-shaped growth portion. Used as a gate electrode material so as to wrap around the tip of the emitter tip above the collared growth and, together with the oxide around the mask and the emitter tip after formation of the gate electrode layer. 27. The collared growth portion is removed.
A method for manufacturing the cathode device according to 1. 28. The step of forming the emitter tip comprises the step of forming a mask for the emitter tip on the substrate,
Including a step of etching the substrate using the mask and a step of removing the mask, wherein the mask removing step is performed before the oxide film forming step, and the oxide film on the substrate is removed from the substrate and the oxide film. 10. The method for manufacturing a cathode device according to claim 9, which is an insulating layer between the gate electrode layer and the gate electrode layer. 29. The step of forming an emitter tip comprises the step of forming a mask for the emitter tip on a substrate,
An opening for exposing the emitter tip between the substrate and the gate electrode layer before the oxide film forming step, the step including etching the substrate using the mask and removing the mask; 10. The method for manufacturing a cathode device according to claim 9, further comprising: a step of forming an insulating layer having: and the mask removing step is performed before the oxide film forming step. 30. In the step of forming the gate electrode layer,
10. The method for manufacturing a cathode device according to claim 9, wherein the gate electrode material is vapor-deposited on the substrate in a direction oblique to the rotation axis while rotating the substrate about the rotation axis. 31. In the step of forming the gate electrode layer,
The method of manufacturing a cathode device according to claim 9, wherein the gate electrode material is attached to the substrate by a sputtering method. 32. In the step of forming the gate electrode layer,
10. The method for manufacturing a cathode device according to claim 9, wherein the gate electrode material is attached to the substrate by a CVD method. 33. In the step of forming an emitter tip,
10. Nearly isotropic etching is performed first, followed by anisotropic etching to form the emitter tip having a conical tip portion and a substantially cylindrical base end portion. The described cathode device. 34. A display device comprising a cathode device and an anode device for receiving electrons emitted from the cathode device, the cathode device comprising a substrate (1) and a conical tip formed on the substrate. And at least one emitter tip (2) having a portion (2A), and a gate electrode layer (4) formed above the substrate and having an opening (4A) exposing a tip portion of the emitter tip. , The diameter of the opening (4A) of the gate electrode layer is equal to the emitter tip (2)
A display device having a diameter smaller than a diameter of a joint portion with the substrate. 35. A plurality of groups of emitter tips (2) are arranged in a matrix form, and the anode device is arranged corresponding to at least one of rows and columns of a matrix of the emitter tips (2). The display device according to claim 34, further comprising: 202).