JP2008294000A - Cold cathode field electron-emitting element and manufacturing method therefor, and cold cathode field electron emission display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an edge cold cathode field electron-emitting element which is superior in the convergence of the tracks of electrons emitted from an electron-emitting layer, and moreover, which is manufactured relatively easily. <P>SOLUTION: The edge cold cathode field electron-emitting element includes the electron-emitting layer 13, an insulating layer 14, and a gate electrode layer 15 that are laminated in the order of increasing on a support 10, and an opening 16 extending from the gate electrode layer 15 to reach the surface of the support 10. The opening 16 is constituted of a first opening 15A formed on the gate electrode layer 15, a second opening 14A formed on the insulating layer 14, and a third opening 13A formed on the electron-emitting layer 13. The first opening 15A, second opening 14A, and third opening 13A communicate with each other. The thickness of the opening end of the third opening 13A, from which electrons are emitted, decreases directed toward the front end of the third opening 13A, and the lower edge of the opening end of the third opening 13A is retreated, as compared to the upper edge of the same. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cold cathode field emission device having excellent electron emission efficiency, a method for manufacturing the same, and a cold cathode field emission display device incorporating such a cold cathode field emission device.

  As an image display device that can replace the mainstream cathode ray tube (CRT), various types of flat display devices have been studied. Examples of such a flat display device include a liquid crystal display device (LCD), an electroluminescence display device (ELD), and a plasma display device (PDP). In addition, a cold cathode field emission display device, so-called field emission display (FED), which can emit electrons from a solid into a vacuum without using thermal excitation has been proposed. Has attracted attention from the viewpoint of.

  In general, a cold cathode field emission display device (hereinafter sometimes simply referred to as a display device) includes a cathode panel having an electron emission region corresponding to each pixel arranged in a two-dimensional matrix, and the electron emission. An anode panel having a phosphor layer that emits light when excited by collision with electrons emitted from the region has a configuration in which the anode panel is disposed to face each other through a vacuum layer. In each electron emission region on the cathode panel, for example, a plurality of electron emission portions are formed, and a gate electrode layer for extracting electrons from the electron emission portions is also formed. The portion having the electron emission portion and the gate electrode layer is a cold cathode field electron emission device, and may be simply referred to as a field emission device hereinafter.

  In such a display device configuration, in order to obtain a large emission electron current with a low driving voltage, for example, the tip shape of the electron emission portion of the field emission device is sharply sharpened, and each electron emission portion is finely formed. Therefore, it is necessary to increase the existence density of the electron emission portions in the section corresponding to one pixel and to shorten the distance between the tip of the electron emission portion and the gate electrode layer. Therefore, in order to realize these, field emission devices having various configurations have been proposed.

  As a representative example of such a conventional field emission device, a so-called Spindt type field emission device (hereinafter referred to as a Spindt type device) in which an electron emission portion is constituted by an electron emission electrode made of a conical conductor. It has been known. A conceptual diagram of a display device incorporating this Spindt element is shown in FIG. The cathode panel of this display device includes a cathode electrode 41 formed on an insulating substrate 40, an interlayer insulating layer 42 formed on the insulating substrate 40 including the cathode electrode, and a gate formed on the interlayer insulating layer 42. The electrode layer 44 includes a conical electron emission electrode 45 formed in an opening 43 provided in the gate electrode layer 44 and the interlayer insulating layer 42. Usually, a predetermined number of electron emission electrodes 45 gather to form one electron emission region, and this electron emission region corresponds to one of the pixels arranged in a two-dimensional matrix. On the other hand, the anode panel has a structure in which a phosphor layer 52 is formed on a substrate 50 in a predetermined pattern, and the phosphor layer 52 is covered with an anode electrode 51.

  When a voltage is applied between the electron emission electrode 45 and the gate electrode layer 44, electrons are drawn from the tip of the electron emission electrode 45 by the electric field generated as a result. The electrons are attracted to the anode electrode 51 of the anode panel and collide with a phosphor layer 52 that is a light emitting layer formed between the anode electrode 51 and the substrate 50. As a result, the phosphor layer 52 is excited to emit light, and a desired image can be obtained. The operation of the cold cathode field emission device is basically controlled by a voltage applied to the gate electrode layer 44.

  An outline of a method for manufacturing such a Spindt-type element will be described below with reference to FIGS. This manufacturing method is basically a method of forming the conical electron emission electrode 45 by vertical vapor deposition of a metal material. That is, the vapor deposition particles are incident on the opening 43 perpendicularly, but the vapor deposition particles reaching the bottom of the opening 43 are utilized by utilizing the shielding effect by the overhanging deposit formed near the opening end. The amount is gradually decreased, and the electron emission electrode 45 which is a conical deposit is formed in a self-aligning manner. Here, a method for forming the separation layer 46 on the gate electrode layer 44 in advance in order to easily remove unnecessary overhang-like deposits will be described. In the following description, an insulating substrate and any structure formed thereon at the stage where an arbitrary process is completed may be collectively referred to as a “base”.

[Step-10]
First, as shown in FIG. 22A, for example, a cathode electrode 41 made of niobium (Nb) is formed on an insulating substrate 40 made of, for example, a glass substrate, and then an interlayer insulating layer 42 made of SiO ₂ is formed thereon. A gate electrode layer 44 made of a conductive material is sequentially formed, and then the gate electrode layer 44 and the interlayer insulating layer 42 are patterned to form an opening 43.

[Step-20]
Next, as shown in FIG. 22B, the release layer 46 is formed by obliquely depositing aluminum on the substrate. At this time, the release layer 46 is formed on the gate electrode layer 44 without substantially depositing aluminum on the bottom of the opening 43 by selecting a sufficiently large incident angle of the vapor deposition particles with respect to the normal of the substrate. Can do. The release layer 46 protrudes in a bowl shape from the opening end of the opening 43, whereby the opening 43 is substantially reduced in diameter.

[Step-30]
Next, for example, molybdenum (Mo) is vertically deposited on the entire surface of the substrate. At this time, as shown in FIG. 23A, as the metal layer 45A having an overhang shape grows on the peeling layer 46, the substantial diameter of the opening 43 is gradually reduced. The vapor deposition particles contributing to the deposition at the bottom of 43 gradually become limited to those passing near the center of the opening 43. As a result, a conical deposit is formed at the bottom of the opening 43, and this conical deposit becomes the electron emission electrode 45.

[Step-40]
Thereafter, as shown in FIG. 23B, the peeling layer 46 is peeled off from the surface of the gate electrode layer 44 by an electrochemical process and a wet process, and the metal layer 45A above the gate electrode layer 44 is selectively removed. To do.

  By the way, the electron emission characteristic of the field emission device having the structure shown in FIG. 23B is the distance from the edge 43 A of the gate electrode layer 44 that forms the upper end of the opening 43 to the tip of the electron emission electrode 45. It depends heavily. This distance is the processing accuracy of the shape of the opening 43, the dimensional accuracy of the diameter, the film thickness accuracy of the metal layer 45A formed in [Step-30], and the shape accuracy of the peeling layer 46 as the foundation. Depends heavily on

  However, it is actually possible to form the metal layer 45A having a uniform thickness over the entire large-area substrate by vertical vapor deposition, or to form the peeling layer 46 having a uniform ridge shape by oblique vapor deposition. It is extremely difficult, and some in-plane variation or lot-to-lot variation is inevitable. This variation causes variations in image display characteristics of the display device, for example, image brightness. Moreover, when a large vapor deposition apparatus is required, throughput decreases, and when the peeling layer 46 formed over a large area is removed, the residue causes contamination of the cathode panel. There is also a problem of reducing the manufacturing yield.

  On the other hand, a so-called edge-type field emission element (hereinafter referred to as an edge-type element) is known as a field-emission element that can eliminate these drawbacks of the Spindt-type element. Instead of a conical electron emission electrode in a Spindt-type device, an electron emission layer formed in a plane parallel to an insulating substrate is laminated with a gate electrode layer via an insulation layer, and an opening is formed in this laminate. This is a type of element that is used as an electron emission portion by projecting the tip (edge) of the electron emission layer exposed on the wall surface of the opening from the wall surface by some method.

  For example, US Pat. No. 5,214,347 discloses a structure in which an electron emission layer is sandwiched between a pair of gate electrode layers with an insulating layer interposed therebetween and a strong electric field can be applied to the electron emission layer. That is, as shown in FIG. 24, the conductive layer 61, the first insulating layer 62, the lower gate electrode layer 63, the second insulating layer 64, the electron emission layer 65, the third insulating layer 66, and the upper gate are formed on the insulating substrate 60. An opening 68 is provided in the stacked body in which the electrode layers 67 are sequentially stacked. Then, the electrons e emitted from the tip of the electron emission layer 65 protruding from the wall surface of the opening 68 are led out to the outside of the opening 68. The radius of curvature of the tip of the electron emission layer 65 is reduced by reducing the film thickness by isotropic etching, thereby increasing the electron emission density. The conductive film 69 facing the upper gate electrode layer 67, the electron emission layer 65, and the lower gate electrode layer 63 constitutes an electrode for attracting electrons emitted from the electron emission layer 65, and The conductive layer 61 exposed at the bottom of the opening 68 is provided for the purpose of surface protection, potential stabilization, prevention of dielectric breakdown and noise.

  In the edge type device, since the distance from the edge of the gate electrode layer to the electron emission layer can be almost determined by the thickness of the insulating layer, control of this distance is much easier than in the Spindt type device, In this sense, the disadvantages of Spindt-type elements are considerably eliminated. Therefore, it is easy to make the electron emission characteristics of the electron emission portion uniform even on a large-area substrate, and the brightness of the image of the display device can be made uniform. However, the shape of the electron emission portion is not a sharp “point” as in the Spindt-type device but “line”, and the gate electrode layer is associated with the shape of the electron emission portion as compared with the case of the Spindt-type device. Since the opening is large, the effect of confining the electric field inside the opening becomes weak, and electric field concentration hardly occurs in the vicinity of the electron emission portion. In other words, the edge-type device has lower electron emission efficiency than the Spindt-type device, and requires a higher gate voltage to obtain an emission electron current equivalent to the Spindt-type device. It is difficult to reduce power.

  Further, unlike the Spindt-type device in which the tip of the electron-emitting electrode is sharpened in the direction of the anode electrode and the emitted electrons can travel almost straight toward the anode electrode, the electron-emitting portion of the edge-type device has an opening portion. Since it protrudes from the side wall, part of the emitted electrons can travel below the plane of the electron emission layer, that is, in the direction opposite to the anode electrode. When the electrons traveling downward in this way collide with any obstacle in the opening, they themselves become recoiled electrons, or secondary electrons are knocked out from the surface of the obstacle. If these recoil electrons and secondary electrons are also attracted to the anode electrode and collide with the phosphor layer, they can ultimately contribute to light emission. However, the energy distribution width of recoil electrons and secondary electrons is wider than the energy distribution width of electrons emitted from the tip of the electron emission electrode and proceeding directly toward the anode electrode. Depending on the structure, it may be difficult to control the trajectory of recoil electrons and secondary electrons so as to collide with a predetermined phosphor layer.

  SUMMARY OF THE INVENTION A first object of the present invention is to provide an edge-type cold cathode field emission device that can improve electron emission efficiency and is relatively easy to manufacture, a method for manufacturing the same, and such a cold cathode field emission device. It is an object of the present invention to provide a cold-cathode field electron emission display device incorporating the above. A second object of the present invention is an edge-type cold cathode field emission device that is excellent in the convergence of the trajectory of electrons emitted from the electron emission layer and that is relatively easy to manufacture, and a method for manufacturing the same. Another object of the present invention is to provide a cold cathode field emission display device incorporating such a cold cathode field emission device.

The cold cathode field emission device according to the first aspect of the present invention for achieving the first object is as follows:
An electron emission layer, an insulating layer, and a gate electrode layer are laminated on the support in this order,
An opening reaching the surface of the support from the gate electrode layer is provided,
The opening includes a first opening provided in the gate electrode layer, a second opening provided in the insulating layer, and a third opening provided in the electron emission layer,
The first opening, the second opening, and the third opening communicate with each other,
The opening end of the third opening from which electrons are emitted is set back from the opening end of the first opening. Here, the opening end of the first opening is, in other words, the edge of the gate electrode layer facing the opening. The opening end of the third opening is, in other words, the edge of the electron emission layer facing the opening. Therefore, one of the important points of the cold cathode field emission device according to the first aspect is, in other words, a structure in which the edge of the electron emission layer recedes from the edge of the gate electrode layer in the opening. is there.

The cold cathode field emission device according to the second aspect of the present invention for achieving the second object described above,
An electron emission layer, an insulating layer, and a gate electrode layer are laminated on the support in this order,
An opening reaching the surface of the support from the gate electrode layer is provided,
The opening includes a first opening provided in the gate electrode layer, a second opening provided in the insulating layer, and a third opening provided in the electron emission layer,
The first opening, the second opening, and the third opening communicate with each other,
The thickness of the opening end of the third opening from which electrons are emitted decreases toward the tip, and the lower edge of the opening end of the third opening recedes from the upper edge. And In other words, one of the important points of the cold cathode field emission device according to the second aspect is that the electron emission portion, that is, the edge of the electron emission layer facing the opening has a reverse tapered wall. It is in.

  In this specification, the term “projection” of an opening end of a certain opening means that the opening end is closer to the center of the opening along the extending direction of the layer in which the opening is provided. It means that there is. Further, “retreat” of the opening end portion of a certain opening portion means that the opening end portion is located farther from the center of the opening portion along the extending direction of the layer in which the opening portion is provided. .

  In the cold cathode field emission device according to the first aspect, the fact that the opening end of the third opening is recessed from the opening end of the first opening means that the first opening to the support This means that the projected image is included in the projected image of the third opening on the support. That is, when the opening of the cold cathode field emission device is viewed from the direction perpendicular to the support, the edge of the electron emission layer is completely hidden behind the gate electrode layer. Therefore, even if the first opening provided in the gate electrode layer is somewhat large, the effect of confining the electric field is difficult to decrease, and the electric field strength in the vicinity of the edge of the electron emission layer can be maintained high. It is possible to reduce power consumption. Further, the fact that the opening end of the third opening protrudes from the lower end of the second opening means that the projection image onto the support of the third opening is directed to the support of the lower end of the second opening. It is included in the projected image.

  In the cold cathode field emission device according to the first aspect, X represents a receding amount along the extending direction of the electron emission layer at the opening end of the third opening with respect to the opening end of the first opening, and the gate electrode layer It is preferable that 0 <X / Y ≦ 1.7, where Y is the distance between the electron emission layer and the electron emission layer. When the value of X / Y exceeds 1.7, there is a high possibility that electrons emitted from the electron emission layer collide with the gate electrode and cannot be extracted to the anode electrode side when incorporated in a display device described later. . More preferably, 0.4 ≦ X / Y ≦ 1.2. Unlike the cold cathode field emission device according to the first aspect, the cold cathode field emission device according to the second aspect is different from the upper edge of the opening end of the third opening and the opening end of the first opening. The positional relationship with is not particularly limited.

  In the cold cathode field emission device according to the first aspect, it is preferable that the opening end of the third opening protrudes from the lower end of the second opening, and the cooling according to the second aspect. In the cathode field emission device, it is preferable that the upper edge of the opening end of the third opening protrudes from the lower end of the second opening. That is, the opening end of the third opening is a part that actually emits electrons, and it is preferable that this part protrudes rather than being buried in the insulating layer from the viewpoint of increasing electron emission efficiency. .

  In the cold cathode field emission device according to the first aspect, it is more preferable that the thickness of the opening end of the third opening decreases toward the tip. The thickness of the opening end of the third opening may be reduced from the upper edge to the lower edge (ie, forward tapered) or may be reduced from the lower edge to the upper edge (ie, reverse taper). Shape), or from both the upper and lower edges, and the mode of reduction may be monotonic or gradual.

  On the other hand, in the cold cathode field emission device according to the second aspect, when the opening end of the third opening is viewed in a cross section perpendicular to the support, the lower edge recedes from the upper edge of the opening end. It has a taper angle θ corresponding to the degree. The taper angle θ is preferably approximately 10 ° ≦ θ ≦ 80 °, and 20 ° ≦ θ ≦ 70 ° in consideration of the convergence of the emitted electron orbit and the mechanical strength of the electron emission layer. It is more preferable that When the taper angle θ of the opening end is approximately within the above range, the electric field strength can be effectively increased near the opening end, and most of the electrons emitted from the upper edge can be directed outside the opening. It becomes possible. It should be noted that the manner of decreasing the thickness of the opening end of the third opening may be monotonous or stepwise.

  In the cold cathode field emission device according to the first aspect and the second aspect, the planar shapes of the first opening, the second opening, and the third opening are preferably similar, but the above-described geometry As long as the general conditions are satisfied, they may have different planar shapes. Examples of the planar shape of the openings include a circle, an ellipse, and an n-gon (where n is an integer of 3 or more). The n-gon may not be a regular n-gon and its apex may be rounded. Among the n-gons, a rectangle is particularly suitable. In this case, it is preferable to select a long side of the rectangle of about 100 μm and a short side of about several μm to 10 μm.

  In the cold cathode field emission device according to the first aspect and the second aspect, there may or may not be an electrode layer other than the electron emission layer and the gate electrode layer described above. The case where there is no other electrode layer is a case where the support is an insulating substrate, for example. The cold cathode field emission device in this case has a configuration in which, for example, an electron emission layer is formed directly on an insulating substrate, and the insulating substrate is exposed at the bottom of the third opening. A concave portion may be provided in a portion of the insulating substrate immediately below the third opening. The planar shape of the recess at this time is preferably congruent or similar to the planar shape of the third opening, but the projected image of the third opening on the surface of the insulating substrate becomes the projected image of the recess on the surface of the insulating substrate. As long as it is included, the planar shapes of the recess and the third opening may be different from each other.

  When the cold cathode field emission device according to the first aspect has a recess, the deepest portion of the opening does not end at the third opening provided in the electron emission layer, and extends further below the electron emission layer. . This is effective in forming an electric field strength distribution that exhibits a strong electric field convex lens effect in the vicinity of the opening, thereby improving the convergence of the emitted electron trajectory. In the cold cathode field emission device according to the first aspect, the upper end of the recess is made to recede from the opening end of the third opening (that is, the edge of the electron emission layer facing the opening is the wall surface of the recess). The electron emission efficiency can be increased.

  In the cold cathode field emission device according to the second aspect, the upper end portion of the concave portion is aligned with the upper edge of the opening end portion of the third opening portion, or is made to recede from the upper edge to face the opening portion. The edge of the electron emission layer can be protruded from the side wall surface of the recess, and the electron emission efficiency can be increased. In the cold cathode field emission device according to the second aspect, the positional relationship between the upper end of the recess and the lower edge of the opening end of the third opening is not particularly limited. That is, in the cold cathode field emission device according to the second aspect, the upper end portion of the recess may be located at an intermediate position between the upper edge and the lower edge of the opening end portion of the third opening portion, or the third opening portion. It may be aligned with the lower edge of the opening end of the third opening, or may further recede from the lower edge of the opening end of the third opening.

  On the other hand, in the cold cathode field emission device according to the first aspect and the second aspect, when there is another electrode layer, (a) when there is a second gate electrode layer below the electron emission layer, (B) When the focusing electrode layer is above the gate electrode layer, or (c) When both the second gate electrode layer and the focusing electrode layer are present.

  In the cold cathode field emission device in the cases of (a) and (c), the support includes an insulating substrate, a second gate electrode layer formed on the insulating substrate, and an insulation including the second gate electrode layer. A second insulating layer formed on the substrate, and the opening further includes a fourth opening provided in the second insulating layer so as to communicate with the third opening, and the bottom of the fourth opening is The second gate electrode layer can be exposed. In this configuration, the second gate electrode layer can apply an electric field to the electron emission layer in cooperation with the gate electrode layer. Therefore, it is possible to apply a stronger electric field to the electron emission layer than when the gate electrode layer is provided alone. The planar shape of the fourth opening is preferably congruent or similar to the planar shape of the third opening. Furthermore, in the cold cathode field emission device according to the first aspect, the edge portion of the electron emission layer is made to be the opening portion by retracting the upper end portion of the fourth opening portion from the opening end portion of the third opening portion. Projecting from the side wall surface can increase electron emission efficiency. In the cold cathode field emission device according to the second aspect, in which the opening end of the third opening has an inversely tapered wall, the upper end of the fourth opening is the upper edge of the opening end of the third opening. By aligning or retreating from the upper edge, the edge of the electron emission layer can be protruded from the side wall surface of the fourth opening, and the electron emission efficiency can be increased. In any of the cold cathode field emission devices according to any aspect, the planar shape of the fourth opening is preferably similar to the planar shape of the third opening, but the upper end of the fourth opening to the surface of the insulating substrate. As long as the projected image includes the projected image of the third opening on the surface of the insulating substrate, the planar shapes of the fourth opening and the third opening may be different from each other.

  In the cold cathode field emission devices in the cases of (b) and (c), an interlayer insulating layer formed on an insulating layer including the gate electrode layer, and a converging electrode layer formed on the interlayer insulating layer The opening further includes a fifth opening provided in the interlayer insulating layer so as to communicate with the first opening, and a sixth opening provided in the focusing electrode layer so as to communicate with the fifth opening. Furthermore, it can also be set as the structure containing. The planar shape and the size relationship between the first opening provided in the gate electrode layer and the sixth opening provided in the converging electrode layer are not particularly limited. From the viewpoint of obtaining the electric field convex lens effect, the sixth opening is It is desirable that it be larger than one opening. Further, since the potential of the focusing electrode layer is the same as or close to the potential of the electron emission layer, if the opening end of the focusing electrode layer protrudes into the opening, it faces downward from the focusing electrode layer, that is, the gate electrode layer side. There is a possibility that electron emission may occur toward the surface. Therefore, it is preferable that the opening end portion of the sixth opening portion is retracted from the opening end portion of the fifth opening portion provided in the interlayer insulating layer.

The method for manufacturing a cold cathode field emission device according to the first aspect of the present invention for achieving the first object described above (hereinafter referred to as the manufacturing method according to the first aspect) is the first method described above. A method for manufacturing a cold cathode field emission device according to an aspect,
(A) forming an electron emission layer and an insulating layer on a support;
(B) forming a gate electrode layer on the insulating layer;
(C) forming a second opening in the insulating layer at least having a lower end recessed from the opening end of the first opening provided in the gate electrode;
(D) forming a third opening in the electron emission layer, the opening end of which is recessed from the opening end of the first opening by etching the electron emission layer exposed at the bottom of the second opening;
It is characterized by comprising.

A method for manufacturing a cold cathode field emission device according to the second aspect of the present invention for achieving the second object described above (hereinafter referred to as a manufacturing method according to the second aspect) A method for producing a cold cathode field emission device according to aspect 2,
(A) forming an electron emission layer and an insulating layer on a support;
(B) forming a gate electrode layer on the insulating layer;
(C) forming a second opening in the insulating layer that communicates with the first opening provided in the gate electrode layer;
(D) By etching the electron-emitting layer exposed at the bottom of the second opening, the thickness of the opening end decreases toward the tip, and the lower edge of the opening end recedes from the upper edge. Forming the third opening formed in the electron emission layer;
It is characterized by comprising.

  In the manufacturing method according to the first aspect and the second aspect, the first opening is actually formed in the gate electrode layer before the second opening is formed in the insulating layer in the step (c). The second opening is formed in communication with the first opening. The first opening may be formed simultaneously with the formation of the gate electrode layer in the step (b), or may be formed prior to the step (c) after the completion of the step (b).

  In the manufacturing method according to the first aspect, the second opening when the step (c) is completed is formed in a state where a so-called undercut occurs under the gate electrode layer, and the second opening It is preferable that the entire wall surface of the first wall is recessed from the opening end of the first opening already formed in the gate electrode layer. Thereby, when the etching in the next step (d) is completed, the opening end of the third opening provided in the electron emission layer can be protruded from the lower end of the second opening. In the manufacturing method according to the second aspect, since the positional relationship between the opening end of the first opening and the opening end of the third opening is not particularly defined, the second opening at the time when step (c) is completed. The positional relationship between the wall surface and the opening end of the first opening is not particularly specified.

  In the manufacturing method according to the first aspect and the second aspect, the etching of the electron emission layer in the step (d) is performed under conditions using ions as a main etching species, such as reactive ion etching (RIE). Can do. In general, etching using ions as a main etching species is often performed for the purpose of forming a vertical wall at the end of the opening, but the mean free path of ions is not sufficiently long, or self-bias or application of an object to be etched is performed. Conditions such as bias is not sufficiently large, ion mass is not sufficiently large, and the frequency of the high frequency that excites plasma is relatively high, and the retention, scattering, and side of etching species at the corner of the etched region Depending on a phenomenon such as lateral migration, a forward tapered wall (that is, a wall inclined in a direction in which the area to be etched decreases as etching progresses deeply) is formed at the opening end of the third opening, or a reverse tapered wall. (That is, a wall inclined in a direction in which the etching area increases as etching progresses deeply) may be formed. That. In particular, in the manufacturing method according to the second aspect, one of the points in the process is to select the etching conditions of the electron emission layer such that the reverse tapered wall is formed at the opening end of the third opening. It becomes.

In the manufacturing method according to the first aspect and the second aspect, when the support is made of an insulating substrate, after the step (d),
(E) forming a recess in a portion of the insulating substrate immediately below the third opening;
May further be included. As a result, the cold cathode field emission device which can extend the deepest part of the opening to the lower side of the electron emission layer and effectively exhibits the electric field convex lens effect near the edge of the electron emission layer facing the opening. Obtainable. Furthermore, in the step (e) of the manufacturing method according to the first aspect, the upper end of the recess may be made to recede from the opening end of the third opening by isotropically etching the insulating substrate. Thereby, the opening end part of the 3rd opening part provided in the electron emission layer can be protruded from the side wall surface of an opening part, and it becomes possible to improve electron emission efficiency. In the step (e) of the manufacturing method according to the second aspect, the insulating substrate is etched to align the upper end of the recess with the upper edge of the opening end of the third opening, or the upper end of the recess. The part may be retracted from the upper edge of the opening end of the third opening. In order to align the upper end of the recess with the upper edge of the opening end of the third opening, anisotropic etching may be performed. On the other hand, when the upper end of the recess is retreated from the upper edge of the opening of the third opening, isotropic etching is performed, or anisotropic etching and isotropic etching are performed. What is necessary is just to combine. In the case where the upper end of the recess is retracted from the upper edge of the opening end of the third opening, the upper end of the recess is an intermediate position between the upper and lower edges of the opening end of the third opening. Examples include a case, a case where the upper end of the recess is aligned with the lower edge of the opening end of the third opening, and a case where the upper end of the recess is further retracted than the lower edge of the opening end of the third opening. Thereby, the edge part of an electron emission layer can be protruded from the side wall surface of a recessed part, and it becomes possible to improve electron emission efficiency.

In the manufacturing method according to the first aspect and the second aspect, the support is formed on the insulating substrate, the second gate electrode layer formed on the insulating substrate, and the insulating substrate including the second gate electrode layer. In the case where the second insulating layer is formed, after the step (d),
(F) forming a fourth opening in a portion of the second insulating layer immediately below the third opening and exposing the second gate electrode layer at the bottom of the fourth opening;
May further be included. The second gate electrode layer exposed at the bottom of the fourth opening can apply an electric field to the electron emission layer in cooperation with the gate electrode layer. Furthermore, in the step (f) of the manufacturing method according to the first aspect, the second insulating layer is isotropically etched, so that the upper end of the fourth opening recedes from the opening end of the third opening. Is preferable. Thereby, the front-end | tip part (or edge part) of an electron emission layer can be protruded from the side wall surface of an opening part, and electron emission efficiency can be improved. In the step (f) of the manufacturing method according to the second aspect, by etching the second insulating layer, the upper end portion of the fourth opening portion is aligned with the upper edge of the opening end portion of the third opening portion, Alternatively, the upper end portion of the fourth opening portion may be retracted from the upper edge of the opening end portion of the third opening portion. When the upper end of the fourth opening is aligned with the upper edge of the opening of the third opening, anisotropic etching may be performed. On the other hand, when the upper end portion of the fourth opening portion is retreated from the upper edge of the opening end portion of the third opening portion, isotropic etching is performed or isotropic etching and isotropic etching are performed. A combination with etching may be performed. In the case where the upper end of the fourth opening is retracted from the upper edge of the opening end of the third opening, the upper end of the fourth opening is lower than the upper edge of the opening end of the third opening. A case in which the upper edge of the fourth opening is aligned with the lower edge of the opening edge of the third opening, or an upper edge of the fourth opening is the opening edge of the third opening. A case where the lower edge is further retracted is included. Thereby, the front-end | tip part (or edge part) of an electron emission layer can be protruded from the side wall surface of an opening part, and electron emission efficiency can be improved.

In the manufacturing method according to the first aspect and the second aspect, when providing the focusing electrode layer, following the step (a), an interlayer insulating layer is formed on the entire surface, and the focusing electrode is further formed on the interlayer insulating layer. After forming the layer, a fifth opening can be formed in the interlayer insulating layer. Actually, the sixth opening is formed in the focusing electrode layer before the fifth opening is formed in the interlayer insulating layer, and the fifth opening is formed in communication with the sixth opening. The sixth opening may be formed at the same time when the focusing electrode layer is formed, or may be formed after the focusing electrode layer is formed. After forming the fifth opening, in the step (c), a second opening communicating with the fifth opening is formed in the insulating layer. Prior to the formation of the second opening, as described above, the first opening is actually formed in the gate electrode layer. That is, the formation of the sixth opening is not limited to be performed continuously with the formation of the fifth opening, and the formation of the first opening is not necessarily performed continuously with the formation of the second opening. I can't. Therefore, when the interlayer insulating layer and the focusing electrode layer are provided, the following four cases exist as the order of forming each opening. It should be noted that the first opening described in parentheses indicates that it was formed at the same time when the gate electrode layer was formed, and that the sixth opening described in parentheses was formed at the same time that the focusing electrode layer was formed. To express.
(1) sixth opening → fifth opening → first opening → second opening (2) (first opening) → sixth opening → fifth opening → second opening (3) ( (Sixth opening) → fifth opening → first opening → second opening (4) (first opening) → (sixth opening) → fifth opening → second opening

  The focusing electrode layer is emitted from the electron emission layer in a so-called high voltage type display device in which the potential difference between the anode electrode and the electron emission layer is on the order of several kilovolts and the distance between the electrodes is relatively long. It is a member provided to prevent the divergence of the electron trajectory. By improving the convergence of the emitted electron trajectory, it is possible to reduce the optical crosstalk between the pixels, thereby further miniaturizing the pixels and increasing the definition of the display screen. Note that the focusing electrode layer is not necessarily provided for each cold cathode field emission device, for example, for each column or row of cold cathode field emission devices arranged in a two-dimensional matrix. It may be provided in a strip shape. When the focusing electrode layer is provided in a strip shape, the planar shape of the sixth opening portion is a strip shape, which is different from the planar shapes of the other first to fifth openings.

  In the step (c) of the manufacturing method according to the first aspect and the second aspect, a typical technique for forming the second opening in the insulating layer is a technique for etching the insulating layer. In particular, in the manufacturing method according to the first aspect, at least the lower end portion of the second opening portion needs to recede from the opening end portion of the first opening portion provided in the gate electrode layer. Isotropic etching is performed to form the second opening, or anisotropic etching is performed to form the second opening having the vertical wall, and then the isotropic etching is performed to form the vertical wall. It is preferable to retract. It is preferable to perform isotropic etching also in the steps (e) and (f) of the manufacturing method according to the first aspect. In steps (e) and (f) of the manufacturing method according to the second aspect, when the upper end of the recess or the fourth opening is aligned with the upper edge of the opening end of the third opening, it is anisotropic. Etching may be performed. On the other hand, when the upper end of the recess or the fourth opening is retracted from the upper edge of the opening end of the third opening, isotropic etching is performed from the beginning to form the recess or the fourth opening. Alternatively, it is preferable that the anisotropic etching is performed to form the recess having the vertical wall and the fourth opening, and then the isotropic etching is performed to retract the vertical wall. The isotropic etching can be typically performed under wet etching or dry etching conditions in which radicals are the main etching species. In isotropic etching, the removal of the object to be etched proceeds both in the depth direction and in the in-plane direction, so that the wall surface of the formed second opening, recess or fourth opening is retreated. The amount of retreat can be controlled by adjusting the etching time.

The cold cathode field emission display according to the first aspect of the present invention for achieving the first object described above is an apparatus incorporating the cold cathode field emission device according to the first aspect,
Consists of multiple pixels,
Each pixel is composed of a plurality of cold cathode field electron emission devices, and an anode electrode layer and a phosphor layer provided on the substrate so as to face the plurality of cold cathode field electron emission devices,
Each cold cathode field emission device is a cold cathode field emission display device in which an electron emission layer, an insulating layer, and a gate electrode layer are laminated on a support in this order,
An opening reaching the surface of the support from the gate electrode layer is provided,
The opening includes a first opening provided in the gate electrode layer, a second opening provided in the insulating layer, and a third opening provided in the electron emission layer,
The first opening, the second opening, and the third opening communicate with each other,
The opening end of the third opening from which electrons are emitted is set back from the opening end of the first opening.

The cold cathode field emission display according to the second aspect of the present invention for achieving the second object described above is an apparatus incorporating the cold cathode field emission device according to the second aspect,
Consists of multiple pixels,
Each pixel is composed of a plurality of cold cathode field electron emission devices, and an anode electrode layer and a phosphor layer provided on the substrate so as to face the plurality of cold cathode field electron emission devices,
Each cold cathode field emission device is a cold cathode field emission display device in which an electron emission layer, an insulating layer, and a gate electrode layer are laminated on a support in this order,
An opening reaching the surface of the support from the gate electrode layer is provided,
The opening includes a first opening provided in the gate electrode layer, a second opening provided in the insulating layer, and a third opening provided in the electron emission layer,
The first opening, the second opening, and the third opening communicate with each other,
The thickness of the opening end of the third opening from which electrons are emitted decreases toward the tip, and the lower edge of the opening end of the third opening recedes from the upper edge. And

  The cold cathode field emission display according to the first aspect and the second aspect includes a recess, a second gate electrode, and the like described in relation to the cold cathode field emission device according to the first aspect and the second aspect. Any of the converging electrodes may be provided, and all the provisions described in relation to the cold cathode field emission devices according to the first and second embodiments are all related to the opening end of each opening. apply.

  In the cold cathode field emission display according to the first aspect and the second aspect, it is sufficient that at least the surface of the support or the substrate is made of an insulating material, and the glass substrate has an insulating film on the surface. Examples thereof include a formed glass substrate, a quartz substrate, a quartz substrate having an insulating film formed on the surface, and a semiconductor substrate having an insulating film formed on the surface.

In the cold cathode field emission device according to all aspects of the present invention, the manufacturing method thereof, and the cold cathode field emission display, the gate electrode layer or the second gate electrode layer is made of tungsten (W), niobium (Nb), Metal layers such as tantalum (Ta), titanium (Ti), molybdenum (Mo), chromium (Cr), aluminum (Al), copper (Cu), silver (Au), or alloy layers containing these metal elements, or Compounds containing these metal elements (eg, nitrides such as TiN, silicides such as WSi ₂ , MoSi ₂ , TiSi ₂ , TaSi ₂ ), carbon, transparent conductive materials such as ITO (indium / tin oxide), or impurities It can be formed by using a semiconductor such as silicon or diamond containing silicon. As a method for forming the gate electrode layer or the second gate electrode layer, a printing method can be used in addition to a normal thin film manufacturing process such as a vapor deposition method, a sputtering method, a CVD method, and an ion plating method. The material constituting the gate electrode layer and the material constituting the second gate electrode layer may be the same or different.

  In the cold cathode field emission device according to all aspects of the present invention, the manufacturing method thereof, and the cold cathode field emission display, the electron emission layer is typically made of tungsten (W), tantalum (Ta), or the like. It is formed using a refractory metal material or a semiconductor such as diamond. When the first opening is formed by etching the gate electrode layer, the etching rate of the electron emission layer when forming the third opening in the electron emission layer is faster than the etching rate of the gate electrode layer. It is preferable to select a combination of the material constituting the electron emission layer and the material constituting the gate electrode layer. For example, tantalum (Ta) as the material constituting the electron emission layer and tungsten (W) as the material constituting the gate electrode layer Alternatively, for example, tungsten (W) can be exemplified as a material constituting the electron emission layer, and tantalum (Ta) can be exemplified as a material constituting the gate electrode layer. The thickness is desirably in the range of about 0.05 to 0.5 μm, preferably 0.1 to 0.3 μm, but is not limited to this range.

In the cold cathode field emission device according to any aspect of the present invention, the manufacturing method thereof, and the cold cathode field emission display, the constituent material of the insulating layer, the second insulating layer, or the interlayer insulating layer is SiO ₂ , SiN , SiON, and cured glass paste can be used alone or in appropriate combination. For forming the insulating layer, the second insulating layer, or the interlayer insulating layer, a known method such as a CVD method, a coating method, a sputtering method, or a printing method can be used.

  As described above, the field emission device according to the first aspect of the present invention is a so-called edge type device in which the gate electrode layer is formed on the electron emission layer with the insulating layer interposed therebetween, and the electron facing the opening is formed. The edge of the emission layer is recessed from the edge of the gate electrode layer. Therefore, the electric field can be efficiently concentrated in the opening, and a high emission electron current can be obtained with a low gate voltage. The field emission device according to the second aspect of the present invention is also an edge-type device, and an inverted taper wall is formed at the edge of the electron emission layer facing the opening. Therefore, it is possible to direct most of the electrons emitted from the edge of the electron emission layer directly to the outside of the opening.

  In the display device according to the first aspect incorporating the field emission device according to the first aspect and the display device according to the second aspect incorporating the field emission element according to the second aspect, low power consumption is achieved. Nevertheless, high brightness and high image quality can be achieved. Further, according to the method of manufacturing the field emission device according to the first and second aspects of the present invention, the cross-sectional shape of the opening and the shape of the edge of the electron-emitting layer facing the opening are self-aligned. It is possible to obtain a highly reliable process that is extremely advantageous from the viewpoint of reproducibility and throughput, and that can cope with a large display screen area.

  FIG. 1 shows the most basic configuration of a cold cathode field emission device (hereinafter referred to as a field emission device) according to the first embodiment of the present invention. In this field emission device, an opening 16 is provided in a laminate in which an electron emission layer 13, an insulation layer 14, and a gate electrode layer 15 are laminated in this order on a support 10 made of an insulating substrate. The opening 16 includes three similar openings communicating with each other, that is, a first opening 15A provided in the gate electrode layer 15, a second opening 14A provided in the insulating layer 14, and electron emission. It consists of a third opening 13 A provided in the layer 13. The support 10 is exposed at the bottom of the opening 16. Further, the wall surface of the second opening portion is recessed from the opening end portion of the first opening portion 15A, and the opening end portion of the third opening portion (that is, the edge of the electron emission layer 13 facing the opening portion 16) from this wall surface. Part) protrudes. Note that one pixel is configured by a plurality of such openings 16 being assembled.

  FIG. 1A shows a configuration in which the opening end of the third opening 13 </ b> A provided in the electron emission layer 13 has a vertical wall perpendicular to the support 10. In this case, the vertical wall of the third opening 13A is the tip of the opening end. On the other hand, FIG. 1B shows a configuration in which the opening end of the third opening 13 </ b> A provided in the electron emission layer 13 has an inclined wall inclined with respect to the support 10. In this case, the portion of the inclined wall that protrudes largest toward the center of the opening 16 is the tip of the opening end. 1B shows a configuration in which the inclined wall is a forward tapered wall, it may be a reverse tapered wall. Regardless of whether the opening end of the third opening 13A has a vertical wall or an inclined wall, the field emission device according to the first aspect emits electrons as shown in FIG. 1C. The third opening 13A has a feature in that the opening end of the third opening 13A recedes from the opening end of the first opening 15A. In other words, the projected image of the first opening 15A on the support 10 is included in the projected image of the third opening 13A on the support 10. Although FIG. 1C illustrates a case where the planar shapes of the first opening 15A and the third opening 13A are rectangular, other arbitrary planar shapes are possible.

  The field emission device according to the first aspect can be configured as shown in FIG. 2 as long as the above-described geometric condition is established between the first opening 15A and the third opening 13A. 2A is the same as the configuration shown in FIG. FIG. 2B shows a configuration in which the recess 24 is provided in the portion of the insulating substrate immediately below the third opening 13A when the support 10 is made of an insulating substrate. The upper end portion of the recess 24 is recessed from the opening end portion of the third opening portion 13A. FIG. 2C shows a configuration in which an interlayer insulating layer 25 and a focusing electrode layer 26 are provided in the configuration of FIG. The interlayer insulating layer 25 formed on the insulating layer 14 including the gate electrode layer 15 is provided with a fifth opening 25A so as to communicate with the first opening 15A. The focusing electrode layer 26 formed on the interlayer insulating layer 25 is provided with a sixth opening 26A so as to communicate with the fifth opening 25A. FIG. 2D shows a configuration in which a recess 24 is added to the configuration shown in FIG. In FIG. 2E, the support 10 is formed on the insulating substrate 100, the second gate electrode layer 11 formed on the insulating substrate 100, and the insulating substrate 100 including the second gate electrode layer 11. The structure which consists of the 2nd insulating layer 12 and the opening part 16 contains the 4th opening part 12A further provided in the 2nd insulating layer 12 is shown. The upper end portion of the fourth opening portion 12A is retracted from the opening end portion of the third opening portion 13A. FIG. 2F shows a configuration in which an interlayer insulating layer 25 and a focusing electrode layer 26 are added to the configuration shown in FIG.

  3 and 4 show the most basic configuration of the field emission device according to the second embodiment. FIG. 3A is a schematic end view of the field emission device, and FIG. 3B is a top view. 3 and 4 are the same as those in FIG. 1, and detailed description of each part is omitted. The thickness of the opening end of the third opening 13A from which electrons are emitted decreases toward the tip, and the lower edge of the opening end of the third opening 13A recedes from the upper edge. . That is, the opening end of the third opening 13A has a reverse tapered wall. One pixel of the display device is configured by a plurality of such openings 16. The upper edge of the opening end of the third opening 13A of the field emission device shown in FIG. 3A is aligned with the opening end of the first opening 15A. Accordingly, the first opening 15A and the third opening 13A in FIG. 3B overlap.

  FIG. 4A shows a field emission device in which the upper edge of the opening end of the third opening 13A is set back from the opening end of the first opening 15A, and FIG. A field emission device in which the upper edge of the opening end of the third opening 13A protrudes from the opening end of the first opening 15A is shown. FIG. 4B is a top view collectively showing these field emission devices. Note that the planar shapes of the first opening 15A and the third opening 13A shown in FIGS. 3 and 4 are not limited to rectangles, and may be other arbitrary planar shapes.

  In the field emission device according to the second aspect, the thickness of the opening end of the third opening 13A from which electrons are emitted decreases toward the tip, and the lower edge of the opening end recedes from the upper edge. As long as this is done, the configuration shown in FIG. 5 is also possible. 5A is the same as the configuration shown in FIG. FIG. 5B shows a configuration in which the concave portion 24 is provided in the portion of the insulating substrate immediately below the third opening 13A when the support 10 is made of an insulating substrate. A case where the upper end portion of the concave portion 24 is at an intermediate position between the upper edge and the lower edge of the opening end portion of the third opening portion 13A is indicated by a solid line, and a case where the upper end portion is further retracted from the lower edge is indicated by a broken line. FIG. 5C shows a structure in which an interlayer insulating layer 25 and a focusing electrode layer 26 are provided in the structure of FIG. The interlayer insulating layer 25 formed on the insulating layer 14 including the gate electrode layer 15 is provided with a fifth opening 25A so as to communicate with the first opening 15A. The focusing electrode layer 26 formed on the interlayer insulating layer 25 is provided with a sixth opening 26A so as to communicate with the fifth opening 25A. FIG. 5D shows a configuration in which a recess 24 is added to the configuration shown in FIG. The expression by the solid line and the broken line is the same as (B) of FIG. In FIG. 5E, the support 10 is formed on the insulating substrate 100, the second gate electrode layer 11 formed on the insulating substrate 100, and the insulating substrate 100 including the second gate electrode layer 11. The structure which consists of the 2nd insulating layer 12 and the opening part 16 contains the 4th opening part 12A further provided in the 2nd insulating layer 12 is shown. The case where the upper end of the fourth opening 12A is in the middle position between the upper edge and the lower edge of the opening end of the third opening 13A is indicated by a solid line, and the case where the upper end is further retracted than the lower edge is indicated by a broken line. . FIG. 5F shows a configuration in which an interlayer insulating layer 25 and a focusing electrode layer 26 are added to the configuration shown in FIG. The expression by the solid line and the broken line is the same as (E) of FIG.

(Embodiment 1)
In the first embodiment, as a representative example of the field emission device according to the first mode, the field emission device having the configuration shown in FIG. 2E and the first mode for manufacturing the field emission device are shown. And a cold cathode field emission display device (hereinafter referred to as a display device) according to a first aspect incorporating the field emission device. FIG. 6 shows a part of the field emission device in the vicinity of the opening 16 in a partially broken view, and FIG. 7 shows a cross section along the line AA in FIG. 6 including the periphery of the opening. In the insulating layer 14, a first hole 17 is formed as an electrical connection for supplying a predetermined voltage to the electron emission layer 13 in a region adjacent to the formation region of the second opening 14 </ b> A. The second insulating layer 12 has a second hole 18 serving as an electrical connection for supplying a predetermined voltage to the second gate electrode layer 11 in a region adjacent to the formation region of the fourth opening 12A. Is formed.

  Hereinafter, a method of manufacturing the field emission device according to the first aspect will be described with reference to FIGS. In the following description, an insulating substrate and any structure formed thereon at the stage where an arbitrary process is completed may be collectively referred to as a “base”.

[Step-100]
First, as an example, a tungsten film having a thickness of about 0.2 μm is formed on an insulating substrate 100 made of a glass substrate by sputtering, and this tungsten film is patterned by photolithography and dry etching according to a normal procedure. A gate electrode layer 11 is formed. Next, the second insulating layer 12 is formed on the entire surface. Here, as an example, SiO ₂ is formed to a thickness of about 0.3 μm. Further, a conductive film made of tantalum is formed on the second insulating layer 12 to a thickness of 0.2 μm and then patterned into a predetermined shape to form the electron emission layer 13. Next, an insulating layer 14 made of, for example, SiO ₂ is formed on the entire surface to a thickness of about 0.7 μm, for example. Furthermore, a gate electrode layer 15 can be obtained by forming a tungsten film having a thickness of about 0.2 μm on the insulating layer 14 and performing predetermined patterning. The constituent material and thickness of the gate electrode layer 15 may be the same as or different from those of the second gate electrode layer 11. A state where the process so far is completed is shown in FIG.

[Step-110]
Next, as shown in FIG. 8B, the insulating layer 14 and the second insulating layer 12 are patterned, and a first hole serving as an electrical connection for supplying a predetermined voltage to the electron-emitting layer 13 is formed. A portion 17 and a second hole portion 18 serving as an electrical connection portion for supplying a predetermined voltage to the second gate electrode layer 11 are formed.

[Step-120]
Next, a resist layer 19 is formed on the entire surface of the base, and a resist opening 19A is formed in the resist layer 19 so that a part of the surface of the gate electrode layer 15 is exposed. The resist opening 19A can be formed through normal photolithography and development processing, and does not require any special technique or delicate control such as defocus exposure or formation of a poorly soluble layer in a chemically amplified resist material. . The planar shape of the resist opening 19A is rectangular, and FIG. 9A shows a cross section in the short side direction. The long side of the rectangle is approximately 100 μm, and the short side is several μm to 10 μm. Subsequently, the gate electrode layer 15 exposed at the bottom of the resist opening 19A is anisotropically etched by, for example, RIE (reactive ion etching) to form the first opening 15A. Here, since the gate electrode layer 15 is made of tungsten, the first opening 15A having a vertical wall at the opening end can be formed by etching using SF ₆ gas (FIG. 9 ( A)).

[Step-130]
Next, as shown in FIG. 9B, the insulating layer 14 exposed at the bottom of the first opening 15A is isotropically etched to form the second opening 14A. Here, since the insulating layer 14 is formed using SiO ₂ , wet etching using a buffered hydrofluoric acid aqueous solution is performed. The wall surface of the second opening 14A recedes from the opening end of the first opening 15A, and the amount of receding at this time can be controlled by the length of the etching time. Here, wet etching is performed until the lower end portion of the second opening portion 14A recedes from the opening end portion of the first opening portion 15A. The insulating layer 14 may be etched by combining dry etching and wet etching. For example, after forming the second opening 14A having a vertical wall by anisotropic dry etching, the vertical wall may be retracted by isotropic wet etching. Such a combination of two types of etching can be similarly applied to the etching of the second insulating layer 12 described later.

[Step-140]
Next, as shown in FIG. 10A, the electron-emitting layer 13 exposed at the bottom of the second opening 14A is dry-etched under conditions using ions as the main etching species to form the third opening 13A. To do. Thus, a vertical wall is formed at the opening end of the third opening 13A at a position substantially aligned with the lower end of the second opening 14A. As the etching gas, SF ₆ can be used. However, in the case where an incident component having an angle other than normal exists in the main etching species in the plasma, or an oblique incident component is generated by scattering at the opening end of the first opening, the electron emission layer Among the 13 edges, the main etching species also enters the area shielded by the vertical projection image of the first opening 15A with a certain probability. In such a case, a forward tapered wall as shown in FIG. 1B is formed at the opening end of the third opening 13A. That is, the thickness of the edge of the electron emission layer 13 facing the opening 16 becomes thinner toward the tip in the protruding direction, and the tip is sharpened.

[Step-150]
Next, as shown in FIG. 10B, the second insulating layer 12 exposed at the bottom of the third opening 13A is isotropically etched to form the fourth opening 12A. Finalize. Here, as in the case of the second insulating layer 14 described above, wet etching using a buffered hydrofluoric acid aqueous solution is performed. The wall surface of the fourth opening 12A recedes from the opening end of the third opening 13A. The amount of retreat at this time can be controlled by adjusting the length of the etching time, but the upper end of the fourth opening 12A needs to be retreated from the opening end of the third opening 13A provided in the electron emission layer 13. . At this time, the wall surface of the previously formed second opening 14A is further retracted. If the resist layer 19 is removed after the opening 16 is completed, the configuration shown in FIG. 7 can be obtained.

  A large number of field emission devices fabricated as described above are actually assembled to constitute a cathode panel. When this cathode panel is combined with the anode panel 23 as shown in FIG. 11 and connected to an external power supply circuit, the display device 30 according to the first aspect is completed. The space between the cathode panel and the anode panel 23 is a high vacuum. In the actual configuration of the display device, the peripheral edge of the anode panel and the peripheral edge of the cathode panel are joined via a spacer and / or a frame, and the space between these two panels is exhausted. Further, the anode panel 23 is provided with a phosphor layer and an anode electrode layer formed in a predetermined pattern (not shown). The external power supply circuit includes a first gate electrode power supply 20, a second gate electrode power supply 21, and an anode power supply 22, and a pulsed positive voltage (eg, 0) is applied to the second gate electrode layer 11 and the gate electrode layer 15. A positive voltage larger than this is applied to the anode electrode layer (not shown) of the anode panel 23. For example, a pulsed positive voltage may be applied to the second gate electrode layer 11 and a constant positive voltage may be applied to the gate electrode layer 15. Further, a negative voltage is applied to the electron emission layer 13 or is grounded.

When the display device is manufactured by bonding the anode panel 23 and the cathode panel at the peripheral edge, the peripheral edge may be bonded only by frit glass or a low melting point metal material, or bonded through a frame. May be. When the frame is used, the adhesion between the frame and the anode panel 23 and the adhesion between the frame and the cathode panel can be performed using frit glass or a low melting point metal material. Here, the “low melting point” of the low melting point metal material generally refers to a temperature range of 400 ° C., and the material is appropriately selected from among indium, indium alloy, tin solder, lead solder, and zinc solder. You can choose. Such a low-melting-point metal material is less prone to degassing than frit glass, and thus is suitable for maintaining the degree of vacuum in the internal space of the display device for a long period of time, thereby extending the life of the display device. is there. In manufacturing the display device, for example, a frame body (not shown) made of ceramics or glass and having a height of about 1 mm is prepared, and the frame body, the anode panel 23 and the cathode panel are temporarily bonded using frit glass. Then, it may be baked at about 450 ° C. for 10 to 30 minutes. Thereafter, the internal space of the display device is evacuated to a vacuum of about 10 ⁻⁴ Pa and sealed by an appropriate method. Alternatively, the frame, the anode panel 23, and the cathode panel may be bonded to each other using a frit glass, a low melting point metal material, or a frame in the vacuum chamber. Since this is a high vacuum, evacuation in the subsequent process becomes unnecessary.

In the configuration of the display device 30, an electric field is applied from the gate electrode layer 15 and the second gate electrode layer 11 to the edge of the electron emission layer 13 facing the opening 16, and from the edge of the electron emission layer 13 by the quantum tunnel effect. Electrons are emitted. Part of the emitted electrons (e ₁ ) directly goes from the opening 16 to a phosphor layer (not shown), and the other part is recoiled electrons (e ₂₎ recoiled on the surface of the second gate electrode layer 11. ) Toward the phosphor layer. Secondary electrons may be emitted from the surface of the second gate electrode layer 11 due to collision of electrons emitted from the electron emission layer 13, and the secondary electrons (e ₃ ) are also directed to the phosphor layer. All of these electrons e ₁ , e ₂ , and e ₃ ultimately contribute to exciting the phosphor layer and emitting it. In the field emission device according to the first aspect, since the portion corresponding to the electron exit of the opening 16 is narrowed by the first opening 15A provided in the gate electrode layer 15, the electric field is generated inside the opening 16. Is effectively confined. If this state is expressed using equipotential lines, the interval between equipotential lines is close to the edge of the electron emission layer 13, and a strong electric field is efficiently applied to the edge of the electron emission layer 13. Means that. Therefore, according to the field emission device according to the first aspect, a sufficient emission electron current can be obtained even when the voltages applied to the gate electrode layer 15 and the second gate electrode layer 11 are relatively low. That is, a field emission device with low power consumption and high electron emission efficiency is realized, and the brightness and image quality of a display device incorporating such a field emission device are improved.

(Embodiment 2)
In the second embodiment, as a representative example of the field emission device according to the second mode, the field emission device having the configuration shown in FIG. 5E and the second mode for manufacturing the field emission device are shown. And a display device according to a second aspect incorporating the field emission device. FIG. 12 shows a part of the field emission device in the vicinity of the opening 16 in a partially broken view, and FIG. 13 shows a cross section along the line AA in FIG. 12 including the periphery of the opening. Reference numerals in these drawings are the same as those in FIGS. 6 and 7. The second embodiment is different from the first embodiment in that a reverse tapered wall is formed at the opening end of the third opening 13A provided in the electron emission layer 13.

  Hereinafter, a method for manufacturing the field emission device according to the second aspect will be described with reference to FIG.

[Step-200]
First, [Step-100] to [Step-130] are performed in the same manner as in the first embodiment. Next, the electron emission layer 13 made of tantalum exposed at the bottom of the second opening 14A is dry-etched according to the conditions shown in Table 1 below as an example to form the third opening 13A. With this etching condition, as shown in FIG. 14A, the thickness of the opening end of the third opening 13A from which electrons are emitted decreases toward the tip, and the third opening 13A. The lower edge of the open end of the first electrode recedes from the upper edge (that is, an inverted tapered wall is formed at the edge of the electron emission layer 13). In the example shown in the figure, the opening end of the first opening 15A and the opening end of the third opening 13A are in a aligned position, but they may not be aligned.

[Table 1]
Etching device: parallel plate RIE (reactive ion etching) device SF ₆ flow rate: 100 SCCM
Pressure: 10Pa
RF power: 200W (13.56MHz)

[Step-210]
Next, as shown in FIG. 14B, the second insulating layer 12 exposed at the bottom of the third opening 13A is isotropically etched to form the fourth opening 12A. Finalize. Here, as in the case of the insulating layer 14 described above, wet etching using a buffered hydrofluoric acid aqueous solution is performed. The retreat amount of the wall surface of the fourth opening 12A at this time can be controlled by the length of the etching time, but here, the third opening provided in the electron emission layer 13 at the upper end of the fourth opening 12A. The upper edge of the opening end of 13A is further retracted from the lower edge. At this time, the wall surface of the previously formed second opening 14A is further retracted. If the resist layer 19 is removed after the opening 16 is completed, the configuration shown in FIG. 13 can be obtained.

  A large number of field emission devices fabricated as described above are actually assembled to constitute a cathode panel. When this cathode panel is combined with the anode panel 23 as shown in FIG. 15 and connected to an external power supply circuit, the display device 31 according to the second mode is completed. The reference numerals in FIG. 15 are the same as the reference numerals in FIG. The manufacturing method of the display device 31 is as described above in relation to the display device 30.

In such a configuration of the display device 31, an electric field is applied from the gate electrode layer 15 and the second gate electrode layer 11 to the edge of the electron emission layer 13 facing the opening 16, and the opening end of the third opening 13A is caused by the quantum tunnel effect. Electrons are emitted from the portion (more specifically, the upper edge). The thickness of the opening end of the third opening from which electrons are emitted decreases toward the tip, and a reverse taper wall is formed at the opening so that the electron is emitted from the opening end. Most of the electrons (e ₁ ) are drawn out of the opening 16 as they are and go directly to a phosphor layer (not shown). Thus, since the electron (e ₁ ) that goes directly to the phosphor layer has a narrow energy distribution width, it is relatively easy to control the trajectory to collide with a predetermined phosphor layer. On the other hand, the surface of the second gate electrode layer 11 due to collision of recoil electrons (e ₂ ) directed to the phosphor layer after being recoiled on the surface of the second gate electrode layer 11 or electrons emitted from the electron emission layer 13. There are also some secondary electrons (e ₃ ) knocked out from However, in the display device according to the second aspect, the abundance ratio of the recoil electrons (e ₂ ) and secondary electrons (e ₃ ) is extremely small compared to the electrons (e ₁ ) that go directly to the phosphor layer. There is almost no possibility of adversely affecting the convergence of the emitted electron orbit.

The magnitude relationship between the voltages applied to the gate electrode layer 15 and the second gate electrode layer 11 can be selected according to the thicknesses of the insulating layer 14 and the second insulating layer 12. For example, the thickness of the insulating layer 14 is t ₁ , the thickness of the second insulating layer 12 is t ₂ , the voltage applied to the gate electrode layer 15 is V ₁ , and the voltage applied to the second gate electrode layer 11 is V ₂ . Then, t ₁ <t ₂ is preferable when V ₁ and V ₂ are set to substantially equal levels, and V ₁ > V ₂ is set when t ₁ and t ₂ are set approximately equal. It is preferable.

  As mentioned above, although this invention was demonstrated based on embodiment of this invention, this invention is not limited to these embodiment at all. The details of the structure of the field emission device and the details of the structure of the display device to which the field emission device is applied are examples, and can be appropriately changed, selected, and combined. For example, any of the field emission devices according to the first aspect shown in FIG. 2 can be applied as constituent elements of the display device according to the first aspect, and according to the second aspect shown in FIG. Any field emission device can be applied as a component of the display device according to the second embodiment. In addition, details, such as details of the structure of the field emission device, processing conditions in the manufacturing method, and materials used, can be appropriately changed, selected, and combined.

  For example, with respect to the field emission device according to the first aspect, field emission devices other than those shown in FIG. 2E can be basically manufactured by the same process. For example, in order to manufacture the field emission device shown in FIG. 2B, first, as shown in FIG. 16A, the electron emission layer 13, the insulating layer 14, and the gate electrode layer are formed on the support 10. 15 are formed in this order. In this case, the support 10 is made of an insulating substrate. Next, the gate electrode layer 15, the insulating layer 14, and the electron emission layer 13 are sequentially etched in accordance with the above-described process to form the opening 16 (see FIG. 16B). Next, the recess 24 is formed in the portion of the insulating substrate directly below the third opening 13A (see FIG. 16C). The recess 24 can be formed by anisotropic dry etching when the upper end is aligned with the opening end of the third opening 13A, but the upper end is made to recede from the lower edge of the third opening 13A. In some cases, it can be formed by isotropic etching or a combination of anisotropic etching and isotropic etching.

  In order to manufacture the field emission device according to the first mode shown in FIG. 2F, first, as shown in FIG. 17A, the second gate electrode layer 11 is formed on the insulating substrate 100. The second insulating layer 12, the electron emission layer 13, the insulating layer 14, the gate electrode layer 15, the interlayer insulating layer 25, and the focusing electrode layer 26 are formed in this order. Here, a stacked body of the insulating substrate 100, the second gate electrode layer 11, and the second insulating layer 12 corresponds to the support 10. Next, as shown in FIG. 17B, the focusing electrode layer 26 is etched to form the sixth opening 26A, and the interlayer insulating layer 25 is further etched to form the fifth opening 25A. In FIG. 17B, the fifth opening 25A provided in the interlayer insulating layer 25 is smaller than the sixth opening 26A provided in the focusing electrode layer 26. This is a device for preventing electrons from being emitted from the focusing electrode layer 26 to which a voltage substantially equal to 13 is applied. In addition, widening the focusing electrode layer 26 also has an effect of increasing the focal length of the electric field convex lens in the vicinity of the final opening 16. In order to achieve such a configuration, for example, an etching mask for forming the sixth opening 26A and an etching mask for forming the fifth opening 25A may be formed in separate steps. The subsequent process is performed as described above. Thus, the field emission device shown in FIG. 18 can be obtained.

  In the method for manufacturing a field emission device according to the first aspect, when the electron emission layer 13 is formed in [Step-100], the third opening 13A is simultaneously formed depending on the shape of the edge of the electron emission layer 13. can do. This formation can be performed by a printing method other than the combination of the tungsten film formation and the patterning as described above. When the third opening 13A is formed in [Step-100], [Step-140] may be omitted and [Step-150] may be executed following [Step-130]. Similarly, the gate electrode layer 15 and the first opening 15A can be formed simultaneously by, for example, a printing method, and the focusing electrode layer 26 and the sixth opening 26A can be formed simultaneously.

  Regarding the field emission device according to the second embodiment, field emission devices other than those shown in FIG. 5E can basically be manufactured by the same process. For example, in order to manufacture the field emission device shown in FIG. 5B, first, as shown in FIG. 19A, the electron emission layer 13, the insulating layer 14, and the gate electrode layer are formed on the support 10. 15 are formed in this order. In this case, the support 10 is made of an insulating substrate. Next, the gate electrode layer 15, the insulating layer 14, and the electron emission layer 13 are sequentially etched in accordance with the above-described process, thereby forming the opening 16 (see FIG. 19B). Next, a recess 24 is formed in the portion of the insulating substrate immediately below the third opening 13A (see FIG. 19C). The recess 24 can be formed by anisotropic dry etching when the upper end is aligned with the upper edge of the opening end of the third opening 13A, but the upper end is the opening end of the third opening 13A. When it is made to recede from the upper edge, it can be formed by isotropic etching. According to the configuration shown in FIG. 5B, the taper angle θ of the opening end of the third opening 13A is further reduced by etching the electron emission layer 13 again after forming the recess 24. It can also be made. This is because a space is also formed below the electron emission layer 13, so that etching species can enter the back side of the electron emission layer 13.

  Furthermore, in order to manufacture the field emission device according to the second embodiment shown in FIG. 5F, after obtaining the state shown in FIG. 17B as described above, the device shown in FIG. As described above, the first opening 15A, the second opening 14A, the third opening 13A, and the fourth opening 12A may be sequentially formed. In the field emission device manufacturing method according to the second aspect, the converging electrode layer 26 and the sixth opening 26A are simultaneously formed by, for example, a printing method, or the gate electrode layer 15 and the first opening 15A are formed. Formation can occur simultaneously.

  In the manufacturing method according to the first and second aspects, a plurality of grooves are formed in the electron emission layer 13 at the stage shown in FIG. 8A, and the electron emission layer 13 is etched. When the third opening 13A is formed by the above, it is possible to form unevenness at the opening end. A plurality of sharply pointed portions are formed at the opening end according to the number of the groove portions, and electrons are emitted from each of the pointed portions, so that the emission electron current increases, and accordingly The luminance of a display device incorporating a field emission element can be improved.

It is a conceptual diagram which shows the basic composition of the field emission element which concerns on a 1st aspect. It is a conceptual diagram which shows the other structure of the field emission element which concerns on the 1st aspect which added the recessed part and / or focusing electrode layer of the support body in addition to the basic structure of FIG. It is a conceptual diagram which shows the basic composition of the field emission element which concerns on a 2nd aspect. It is a conceptual diagram which shows the other basic structure of the field emission element which concerns on a 2nd aspect. It is a conceptual diagram which shows the other structure of the field emission element which concerns on the 2nd aspect which added the recessed part and / or focusing electrode layer of the support body in addition to the basic structure of FIG. FIG. 3 is a perspective view showing a partially broken opening of a field emission device having the configuration of FIG. FIG. 7 is a schematic end view showing a cross section along line AA in FIG. 6 together with the structure around the opening. It is a typical end view which shows the process common to the manufacturing method which concerns on a 1st aspect and a 2nd aspect, (A) is the state which completed formation of the gate electrode layer, (B) is used for electrode connection The state which formed the 1st hole and the 2nd hole is shown. FIG. 9 is a schematic end view illustrating steps common to the manufacturing method according to the first and second aspects, following FIG. 8, (A) shows a state in which a first opening is formed, and (B) shows a second process. The state which formed the opening part is shown. FIG. 10 is a schematic end view showing the steps included in the manufacturing method according to the first aspect, following FIG. 9, in which (A) shows a state in which a third opening is formed, and (B) shows that a fourth opening is formed. Indicates the state. It is a conceptual diagram which shows the structural example of the display apparatus which concerns on a 1st aspect. FIG. 6 is a perspective view showing a partially broken opening of a field emission device having the configuration of FIG. It is a typical end view which shows the AA line cross section of FIG. 12 with the structure of an opening part periphery. FIG. 10 is a schematic end view showing the steps included in the manufacturing method according to the second aspect, following FIG. 9, in which (A) shows a state in which a third opening is formed, and (B) shows that a fourth opening is formed. Indicates the state. It is a conceptual diagram which shows the structural example of the display apparatus which concerns on a 2nd aspect. It is a typical end view which shows the manufacturing process of the field emission element which has the structure of (B) of FIG. It is a typical end view which shows the manufacturing process of the field emission element which has the structure of (F) of FIG. FIG. 18 is a schematic end view showing a manufacturing step of the field emission device having the configuration of FIG. FIG. 6 is a schematic end view showing a manufacturing process of a field emission device having the configuration of FIG. FIG. 18 is a schematic end view showing a manufacturing step of the field emission device having the configuration of FIG. It is a typical end view which shows the general structural example of the display apparatus incorporating a Spindt type | mold element. It is a typical end view for demonstrating an example of the manufacturing method of the conventional Spindt type | mold element, (A) is the state which formed the opening part, (B) is the state which formed the peeling layer on the gate electrode layer, respectively. To express. FIG. 23 is a schematic end view for explaining an example of a conventional method for manufacturing a Spindt-type device following FIG. 22, in which (A) shows a state in which a conical electron emission electrode is formed as the metal layer grows; B) represents the state in which the unnecessary metal layer is removed together with the release layer. It is a typical end view which shows one structural example of the conventional edge type | mold element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Support body, 11 ... 2nd gate electrode layer, 12 ... 2nd insulating layer, 12A ... 4th opening part, 13 ... Electron emission layer, 13A ... 3rd opening 14, insulating layer, 14 A, second opening, 15, gate electrode layer, 15 A, first opening, 16, opening, 17, first hole. , 18 ... second hole, 20 ... first gate electrode power source, 21 ... second gate electrode power source, 22 ... anode power source, 23 ... anode panel, 25 ... Interlayer insulating layer, 25A ... fifth opening, 26 ... focusing electrode layer, 26A ... sixth opening, 30, 31 ... display device, 100 ... insulating substrate

Claims (15)

An electron emission layer, an insulating layer, and a gate electrode layer are laminated on the support in this order,
An opening reaching the surface of the support from the gate electrode layer is provided,
The opening includes a first opening provided in the gate electrode layer, a second opening provided in the insulating layer, and a third opening provided in the electron emission layer,
The first opening, the second opening, and the third opening communicate with each other,
The thickness of the opening end of the third opening from which electrons are emitted decreases toward the tip, and the lower edge of the opening end of the third opening recedes from the upper edge. A cold cathode field emission device. The cold cathode field emission device according to claim 1 , wherein an upper edge of the opening end of the third opening protrudes from a lower end of the second opening. The cold cathode field emission device according to claim 1 , wherein the support is made of an insulating substrate. The cold cathode field emission device according to claim 3 , wherein a concave portion is provided in a portion of the insulating substrate immediately below the third opening. 5. The cold cathode field electron according to claim 4 , wherein the upper end portion of the recess is located at a position aligned with the upper edge of the opening end portion of the third opening portion or is recessed from the upper edge. Emitting element. The support includes an insulating substrate, a second gate electrode layer formed on the insulating substrate, and a second insulating layer formed on the insulating substrate including the second gate electrode layer,
The opening further includes a fourth opening provided in the second insulating layer so as to communicate with the third opening,
The cold cathode field emission device according to claim 1 , wherein the second gate electrode layer is exposed at the bottom of the fourth opening. 7. The cooling device according to claim 6 , wherein an upper end portion of the fourth opening portion is located at a position aligned with an upper edge of the opening end portion of the third opening portion or recedes from the upper edge. Cathode field electron emission device. An interlayer insulating layer formed on the insulating layer including the gate electrode layer; and a convergence electrode layer formed on the interlayer insulating layer;
The opening further includes a fifth opening provided in the interlayer insulating layer so as to communicate with the first opening, and a sixth opening provided in the focusing electrode layer so as to communicate with the fifth opening. The cold cathode field emission device according to claim 1 , wherein: (A) forming an electron emission layer and an insulating layer on a support;
(B) forming a gate electrode layer on the insulating layer;
(C) forming a second opening in the insulating layer that communicates with the first opening provided in the gate electrode layer;
(D) By etching the electron-emitting layer exposed at the bottom of the second opening, the thickness of the opening end decreases toward the tip, and the lower edge of the opening end recedes from the upper edge. Forming the third opening formed in the electron emission layer;
A manufacturing method of a cold cathode field emission device comprising: The support consists of an insulating substrate,
After the step (d)
(E) forming a recess in a portion of the insulating substrate immediately below the third opening;
The method of manufacturing a cold cathode field emission device according to claim 9 , further comprising: In step (e), by etching the insulating substrate, claim, characterized in that retracting than on either aligned with the edge, or upper edge of the opening end portion of the third opening an upper end of the recess 10 A method for producing a cold cathode field emission device according to claim 1. The support includes an insulating substrate, a second gate electrode layer formed on the insulating substrate, and a second insulating layer formed on the insulating substrate including the second gate electrode layer,
After the step (d)
(F) forming a fourth opening in a portion of the second insulating layer immediately below the third opening and exposing the second gate electrode layer at the bottom of the fourth opening;
The method of manufacturing a cold cathode field emission device according to claim 9 , further comprising: In the step (f), the second insulating layer is etched to align the upper end of the fourth opening with the upper edge of the opening end of the third opening or to recede from the upper edge. A method for manufacturing a cold cathode field emission device according to claim 12 . Subsequent to the step (a), an interlayer insulating layer is formed on the entire surface, and further a step of forming a focusing electrode layer on the interlayer insulating layer, and a step of forming a fifth opening in the interlayer insulating layer,
10. The method of manufacturing a cold cathode field emission device according to claim 9 , wherein in the step (c), a second opening communicating with the fifth opening is formed in the insulating layer. Consists of multiple pixels,
Each pixel is composed of a plurality of cold cathode field electron emission devices, and an anode electrode layer and a phosphor layer provided on the substrate so as to face the plurality of cold cathode field electron emission devices,
Each cold cathode field emission device is a cold cathode field emission display device in which an electron emission layer, an insulating layer, and a gate electrode layer are laminated on a support in this order,
An opening reaching the surface of the support from the gate electrode layer is provided,
The opening includes a first opening provided in the gate electrode layer, a second opening provided in the insulating layer, and a third opening provided in the electron emission layer,
The first opening, the second opening, and the third opening communicate with each other,
The thickness of the opening end of the third opening from which electrons are emitted decreases toward the tip, and the lower edge of the opening end of the third opening recedes from the upper edge. A cold cathode field emission display.

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