JP2008117668A - Field emission element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a field emission element capable of stably field-emitting a sufficient quantity of electrons, and easily manufacturable; and its manufacturing method. <P>SOLUTION: A plurality of wall parts 11 extending in one direction are formed at predetermined intervals and in parallel to one another on the upper surface of an insulation substrate 10. A cross-sectionally L-shaped cathode layer 21 is formed from one side surface of each wall part 11 to a part of the upper surface of the insulation substrate 10. A cross-sectionally L-shaped gate layer 22 is formed from the other side surface of each wall part 11 to a part of the upper surface of the insulation substrate 10. The cathode layer 21 and the gate layer 22 formed on the wall parts 11 adjacent to each other are separated from each other, and electrically insulated from each other. Above the insulation substrate 10, a transparent substrate 50 is arranged through support frames 60 at a predetermined distance. On the undersurface of the transparent substrate 50, a phosphor layer 30 and an anode layer 40 are formed in that order from the insulation substrate 10 side to face the wall parts 11, the cathode layers 21 and the gate layers 22. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a field emission element and a manufacturing method thereof.

  In recent years, field emission displays (field emission display: FED), field emission lamps (field emission lamp: FE lamp), and the like have been developed as field emission devices (field emission devices) using field emission.

  In field emission, the potential barrier of the solid surface that confines electrons in the solid is effectively lowered and thinned by applying a strong electric field in the vicinity of the surface. It is a phenomenon that is radiated by an electric field (for example, in a vacuum).

  In order to cause this phenomenon, an emitter (electron emission source) having a sharp tip is usually provided on the cathode electrode so that electric field concentration is likely to occur.

  For example, in a conventional Spindt-type field emission device, a cathode electrode (cathode), a gate electrode (grid electrode), and an anode electrode (anode) are arranged at predetermined intervals, and a phosphor layer is provided on the surface of the anode electrode. . On the cathode electrode, a conical emitter having a sharp pointed tip is formed so that electric field concentration tends to occur. The gate electrode is provided with a gate hole at a portion facing the emitter.

Since electric field concentration occurs at the tip of the emitter on the cathode electrode, if the potential difference between the cathode electrode and the gate electrode is set to a predetermined value or more (a value significantly lower than the potential difference calculated from the average electric field strength), electrons are emitted from the emitter. Radiated and accelerated by the voltage between the cathode and anode electrodes. When the accelerated electrons collide with the phosphor layer of the anode electrode, the phosphor layer exhibits desired light emission.
JP 2006-156305 A

  However, in the above-described conventional Spindt-type field emission device, the tip of the emitter is formed in a conical shape with a sharp point so that electric field concentration is likely to occur. Therefore, the field emission area is small, and it is emitted from a single emitter. There is a limit to the amount of electrons that can be produced. Therefore, it is difficult for a single emitter to emit a sufficient amount of electrons.

  Thus, a method of manufacturing a plurality of the above-mentioned emitters can be considered, but it is not easy to uniformly manufacture a plurality of cone-shaped emitters with sharp tips. For this reason, the manufacturing yield is low. Furthermore, since a strong electric field is locally applied to the tip portions of the plurality of conical emitters during electron emission, the structure is likely to deteriorate with time and it is difficult to stably emit electrons for a long period of time. Therefore, it is difficult to obtain a stable luminance for a long time.

  An object of the present invention is to provide a field emission element that can stably radiate a sufficient amount of electrons and can be easily manufactured, and a method of manufacturing the same.

  (1) A field emission element according to a first aspect of the present invention is a substrate, a plurality of insulating wall portions formed to have one side surface extending in a predetermined direction on the substrate, and one side surface of the plurality of wall portions. And a plurality of wall portions and an anode electrode disposed at a distance from the upper end portion of the cathode layer so as to face the substrate.

  In the field emission device according to the present invention, a plurality of insulating wall portions are formed on the substrate so as to have side surfaces extending in a predetermined direction, and a cathode layer is formed on one side surface of the plurality of wall portions. . In addition, an anode electrode is disposed at a distance from the plurality of wall portions and the upper end portion of the cathode layer so as to face the substrate.

  When a voltage is applied between the anode electrode and the cathode layer, an electric field concentration depending on the thickness locally occurs at the upper end portion of the cathode layer due to a so-called edge effect. Thereby, electrons are emitted from the linear region constituted by the upper end portion of the cathode layer. Electrons radiated from the upper end of the cathode layer travel toward the anode electrode.

  In this case, since the cathode layer is formed to extend in a predetermined direction on the substrate, a large amount of electrons can be emitted from the linear region at the upper end of the cathode layer.

  In addition, a cathode layer having a uniform thickness can be easily formed on the side surfaces of the plurality of wall portions by a general film forming technique. Thereby, the thickness of the upper end portion of the cathode layer extending in a predetermined direction can be easily formed to be constant. In this case, the cathode layer can be firmly bonded to the insulating wall. Therefore, unlike point emitters such as Spindt-type field emission elements, the upper end of the cathode layer is structurally unlikely to deteriorate with time even if it is thin, and electrons can be stably applied to electric fields even during long-term use. Can radiate.

  (2) The plurality of wall portions are formed so as to further have other side surfaces extending in a predetermined direction on the substrate, and the field emission element further includes a gate layer formed on each of the other side surfaces of the plurality of wall portions. Also good.

  In this case, the amount of electrons from the cathode layer to the anode electrode can be efficiently and easily controlled by applying a small voltage between the gate layer and the cathode layer. In addition, the amount of electrons emitted from the cathode layer by a small voltage change can be greatly changed.

  (3) The field emission element may further include a phosphor layer disposed between the plurality of wall portions and the upper end portion of the cathode layer and the anode electrode.

  In this case, the electrons emitted from the upper end of the cathode layer travel toward the phosphor layer and collide with the phosphor layer. Thereby, the phosphor layer emits light. That is, the field emission element functions as a light emitting element. At this time, since a large amount of electrons can be emitted from the linear region at the upper end of the cathode layer, the luminance can be improved.

  In addition, since the cathode layer is unlikely to deteriorate with time, stable luminance can be obtained even when used for a long time. In addition, luminance flickering is also suppressed.

  (4) According to a second aspect of the present invention, there is provided a method of manufacturing a field emission element, comprising: forming a plurality of insulating wall portions so as to have one side surface extending in a predetermined direction on a substrate; The method includes a step of forming a cathode layer on each of the side surfaces and a step of disposing an anode electrode at a distance from the upper ends of the plurality of wall portions and the cathode layer so as to face the substrate.

  In the method for manufacturing a field emission element according to the present invention, a plurality of insulating wall portions are formed on the substrate so as to have side surfaces extending in a predetermined direction, and a cathode layer is formed on each side surface of the plurality of wall portions. Is done. Furthermore, an anode electrode is disposed at a distance from the plurality of wall portions and the upper end portion of the cathode layer so as to face the substrate.

  In the field emission device thus manufactured, when a voltage is applied between the anode electrode and the cathode layer, the electric field concentration depending on the thickness is locally generated at the upper end portion of the cathode layer by a so-called edge effect. Arise. Thereby, electrons are emitted from the linear region constituted by the upper end portion of the cathode layer. Electrons radiated from the upper end of the cathode layer travel toward the anode electrode.

  In this case, since the cathode layer is formed to extend in a predetermined direction on the substrate, a large amount of electrons can be emitted from the linear region at the upper end of the cathode layer.

  In addition, a cathode layer having a uniform thickness can be easily formed on the side surfaces of the plurality of wall portions by a general film forming technique. Thereby, the thickness of the upper end portion of the cathode layer extending in a predetermined direction can be easily formed to be constant. In this case, the cathode layer can be firmly bonded to the insulating wall. Therefore, unlike point emitters such as Spindt type, the upper end of the cathode layer is structurally resistant to deterioration over time even if it is thin, and electrons are stably emitted even in long-term use. Can do.

  (5) The step of forming the plurality of wall portions includes forming the plurality of wall portions so as to further include another side surface extending in a predetermined direction on the substrate. You may further provide the process of forming a gate layer in the other side of a part, respectively.

  In this case, the amount of electrons from the cathode layer to the anode electrode can be efficiently and easily controlled by applying a small voltage between the gate layer and the cathode layer. Thereby, the amount of electrons emitted from the cathode layer by a small voltage change can be greatly changed.

  (6) The step of forming the cathode layer may include a step of depositing the material of the cathode layer from an oblique direction with respect to one side surface of the plurality of wall portions.

  In this case, a thin cathode layer can be formed on one side surface of the plurality of wall portions with a uniform thickness with good controllability and reproducibility. Thereby, there is little variation in space over a wide area, and electrons can be emitted, and electrons can be emitted sufficiently stably.

  (7) The method of manufacturing a field emission element may further include a step of forming a plurality of wall portions and a phosphor layer disposed between the upper end portion of the cathode layer and the cathode layer.

  Thereby, the light emitting element which consists of a field emission element is manufactured. In this case, the electrons emitted from the upper end of the cathode layer travel toward the phosphor layer and collide with the phosphor layer. Thereby, the phosphor layer emits light. At this time, since a large amount of electrons can be emitted from the linear region at the upper end of the cathode layer, the luminance can be improved.

  In addition, since the cathode layer is unlikely to deteriorate with time, stable luminance can be obtained even when used for a long time. In addition, luminance flickering is also suppressed.

  According to the present invention, a field emission element capable of stably emitting a sufficient amount of electrons in a field can be easily manufactured.

  Hereinafter, a field emission element and a manufacturing method thereof according to an embodiment of the present invention will be described.

(1) First Embodiment (1-1) Configuration of Field Emission Element FIG. 1 is a schematic cross-sectional view of a field emission element according to a first embodiment of the present invention. FIG. 2 is an enlarged perspective view of a part of the field emission element of FIG.

  In this embodiment, the case where a field emission element is applied to a light source or a display device will be described.

  1 and 2, a plurality of insulating walls 11 extending in one direction are formed in parallel on the upper surface of the insulating substrate 10 at predetermined intervals. As a material of the insulating substrate 10, various insulating materials including inorganic materials such as silicate glass, quartz glass, and sapphire, or organic materials such as acrylic and polyethylene can be used. The wall portion 11 may be integrally formed of the same material as that of the insulating substrate 10 or may be formed on the insulating substrate 10 by a material different from that of the insulating substrate 10. As the material of the wall portion 11, various insulating materials such as silicon oxide, silicon nitride, and silicon carbide can be used.

  Each wall portion 11 has both side surfaces perpendicular to the upper surface of the insulating substrate 10 and an upper surface parallel to the upper surface of the insulating substrate 10. Although the width W of the wall part 11 is not specifically limited, For example, they are 1 micrometer-100 micrometers, and are about 10 micrometers in this Embodiment. Although the height H of the wall part 11 is not specifically limited, For example, it is 1 nm-100 micrometers, and is about 1.5 nm in this Embodiment.

  A cathode layer 21 having an L-shaped cross section is formed on a part of the upper surface of the insulating substrate 10 from one side surface of each wall portion 11. A cathode layer 21 having a bar-shaped cross section may be formed on one side surface of each wall portion 11. In addition, a gate layer 22 having an L-shaped cross section is formed on a part of the upper surface of the insulating substrate 10 from the other side surface of each wall portion 11. A gate layer 22 having a bar-shaped cross section may be formed on the other side surface of each wall portion 11.

  The cathode layer 21 and the gate layer 22 are made of a single layer film or a laminated film made of a conductive material such as a metal, a metal compound, or an alloy. The gate layer 22 may be formed of the same material as the cathode layer 21 or may be formed of a different material. The gate layer 22 may have the same structure as the cathode layer 21 or may have a different structure.

  For example, a laminated film in which a metal compound film such as a titanium compound having a small work function is formed on a metal film such as Ti (titanium) is used as the cathode layer 21, and a carbon film can be used as the gate layer 22. Further, as the cathode layer 21, a metal thin film (for example, Ti, W, etc.) having adhesiveness with the wall portion 11 is formed on the surface of the wall portion 11, and the group I or II of the periodic table having a small work function is formed. A laminated film in which a metal film (for example, Rb, Mg, Ba, Ca, etc.) or an alloy film thereof (including an oxide) is formed on the outermost surface may be used. The gate layer 22 may be a metal thin film (for example, Au, Pt) that is a chemically stable conductive material, and may be ITO (indium tin oxide), InOx (indium oxide), ZnO (zinc oxide). A conductive oxide film such as the above may be used. In the present embodiment, in order to simplify the manufacturing process, the cathode layer 21 and the gate layer 22 are formed of the same material and are a laminated film made of a Ti film and a TiN (titanium nitride) film. A TiC (titanium carbide) film may be used instead of the TiN film.

  As shown in FIG. 2, the cathode layer 21 includes a side surface portion 21 a on one side surface of the wall portion 11 and a bottom surface portion 21 b on the upper surface of the insulating substrate 10. Similarly, the gate layer 22 includes a side surface portion 22 a on the other side surface of the wall portion 11 and a bottom surface portion 22 b on the upper surface of the insulating substrate 10.

The thickness t _C of the side surface portion 21a of the cathode layer 21 is formed thinner than the thickness d _C of the bottom surface portion 21b. The thickness _{t G} of the side portion 22a of the gate layer 22 is formed to be thinner than the thickness _{d G} of the bottom portion 22b. The thickness t _C of the side surface portion 21a of the cathode layer 21 is 1 nm to 50 nm, and the thickness t _G of the side surface portion 22a of the gate layer 22 is 1 nm to 100 nm. In the present embodiment, the thickness t _C and the thickness t _G are both about 15 nm. The thickness d _C of the bottom surface portion 21b of the cathode layer 21 and the thickness d _G of the bottom surface portion 22b of the gate layer 22 are not particularly limited, but are preferably 10 nm to 500 nm. In the present embodiment, about 15 nm. It is.

  The cathode layer 21 and the gate layer 22 formed on both side surfaces of one wall portion 11 constitute a set of electron emission sources. As shown in FIG. 1, the cathode layer 21 and the gate layer 22 formed on the adjacent wall portions 11 are separated from each other and electrically insulated.

  A transparent substrate 50 is disposed above the insulating substrate 10 via a support frame 60 at a predetermined interval. On the lower surface of the transparent substrate 50, the phosphor layer 30 and the anode layer 40 are provided in this order from the insulating substrate 10 side so as to face the wall portion 11, the cathode layer 21, and the gate layer 22. The anode layer 40 functions as an anode electrode.

  The phosphor layer 30 may be provided with one phosphor layer 30 that is continuous in common with a plurality of sets of electron emission sources. In this case, the phosphor layer 30 is made of a phosphor for a single color. Thereby, the field emission element is used as a single color light source or display device.

  Or the fluorescent substance layer 30 isolate | separated for every one set or several sets of electron emission sources may be provided, respectively. In this case, the phosphor layer 30 is composed of a red phosphor, a green phosphor, and a blue phosphor. Thereby, the field emission element is used as a color light source or a color display device.

  The anode layer 40 is made of a transparent conductive material such as ITO. The transparent substrate 50 is made of various transparent insulating substrates such as silicate glass, quartz glass, and sapphire.

(1-2) Method for Manufacturing Field Emission Element FIG. 3 is a schematic process cross-sectional view showing a method for mainly manufacturing the cathode layer 21 and the gate layer 22 of the field emission element of FIGS. 1 and 2.

  First, as shown in FIG. 3A, an insulating substrate 10 was prepared, and as shown in FIG. 3B, photoresists 51 were formed in stripes on the upper surface of the insulating substrate 10 at regular intervals by photolithography. Thereafter, a plurality of wall portions 11 are formed on the upper surface of the insulating substrate 10 in parallel with each other at regular intervals by etching.

  Next, as shown in FIG. 3C, a photoresist 52 is formed in a stripe shape at the center between adjacent wall portions 11 on the upper surface of the insulating substrate 10 by photolithography.

  Thereafter, as shown in FIG. 3D, the electrode layer 20 is formed by vapor deposition so as to cover the photoresists 51 and 52, both side surfaces of the wall portion 11, and the upper surface of the insulating substrate 10. In this case, vapor deposition is performed obliquely above one side surface of the plurality of wall portions 11 and obliquely above the other side surface. Thereby, a thin electrode layer 20 is formed on the side surface of each wall portion 11 as compared with the upper surface of each wall portion 11 and the upper surface of insulating substrate 10.

  The electrode layer 20 is made of a single layer film or a laminated film made of a conductive material such as a metal, a metal compound, or an alloy. For example, the electrode layer 20 is a laminated film composed of a metal film and a metal compound film. In the present embodiment, the electrode layer 20 is a laminated film made of a titanium film and a titanium nitride film.

  Next, as shown in FIG. 3E, the photoresists 51 and 52 are removed together with the electrode layer 20 thereon. Thereby, the cathode layer 21 is formed on one side surface of each wall portion 11 and a partial region of the upper surface of the insulating substrate 10 by a lift-off method, and the other side surface of each wall portion 11 and a partial region of the upper surface of the insulating substrate 10. Then, the gate layer 22 is formed.

(1-3) Operation of Field Emission Element Next, the operation of the field emission element shown in FIGS. 1 and 2 will be described. FIG. 4 is a schematic diagram illustrating the operation principle of the field emission element of FIGS. 1 and 2.

  As shown in FIG. 4, the negative electrode and the positive electrode of the variable DC power source E1 are connected to the cathode layer 21 and the anode layer 40, respectively. Further, the negative electrode and the positive electrode of the variable DC power source E2 are connected to the cathode layer 21 and the gate layer 22, respectively. In this case, the DC voltage of the DC power supply E1 is set larger than the DC voltage of the DC power supply E2.

  When a DC voltage is applied between the anode layer 40 and the cathode layer 21 by the variable DC power supply E1, an electric field is concentrated near the upper end portion of the cathode layer 21 due to an edge effect, and electrons are generated from the upper end portion of the cathode layer 21. Radiated. In this case, since the upper end portion of the cathode layer 21 extends linearly in one direction parallel to the upper surface of the insulating substrate 10, the field emission region of the cathode layer 21 becomes linear, and a large amount from the upper end portion of the cathode layer 21. Electrons are emitted in the field.

  Electrons radiated from the upper end of the cathode layer 21 travel toward the anode layer 40 by the electric field between the anode layer 40 and the cathode layer 21. The electrons emitted in the electric field collide with the phosphor layer 30 and the phosphor layer 30 emits light.

  More specifically, the wall portion 11 is sufficiently long along the surface of the insulating substrate 10, and the cross section of the upper end portion of the cathode layer 21 (a surface perpendicular to the surface of the insulating substrate 100) is an ellipse having d as the short axis length. , The maximum electric field generated at the upper end of the cathode layer 21 is derived to be inversely proportional to d. Such electric field concentration in the vicinity of the solid surface occurs only when sufficient free electrons exist like metal and no electric field is generated inside the solid. Therefore, in order to generate a large electric field concentration, it is necessary that sufficient free electrons exist at the upper end portion of the cathode layer 21. For this reason, when the thickness of the cathode layer 21 is extremely thin, electric field concentration as expected may not occur. Further, the extremely thin cathode layer 21 causes a problem in strength. Therefore, a larger electric field concentration is expected as the thickness of the upper end portion of the cathode layer 21 is thinner. However, in practice, although it depends on the material of the cathode layer 21, it is usually desirable to be 1 nm or more. Due to the effect of such electric field concentration, even if the voltage applied to the cathode layer 21 is low, electrons are emitted as long as the local electric field in the vicinity of the surface in the linear region at the upper end of the cathode layer 21 becomes sufficiently strong.

  Here, when a DC voltage is applied between the gate layer 22 and the cathode layer 21 by the variable DC power source E2, a part of the electrons radiated from the upper end of the cathode layer 21 proceeds toward the gate layer 22. The remaining electrons travel toward the anode layer 40.

  On the other hand, when the voltage of the DC power supply E1 is set to 0 and a DC voltage is applied between the gate layer 22 and the cathode layer 21 by the DC power supply E2, electrons emitted from the upper end of the cathode layer 21 by the same edge effect are emitted. Progress toward the gate layer 22. Here, when a DC voltage is applied between the cathode layer 21 and the anode layer 40 by the DC power supply E1, a part or most of the electrons radiated from the upper end of the cathode layer 21 are directed to the anode layer 40. Can do.

  Therefore, the amount of electrons reaching the phosphor layer 30 can be controlled by changing one or both of the DC voltage of the DC power supply E1 and the DC voltage of the DC power supply E2. Thereby, the luminance of the field emission element can be controlled.

  In particular, by controlling the DC voltage of the DC power supply E2, the luminance of the field emission element can be greatly changed by a small voltage change.

  Note that a variable AC power supply may be used instead of the variable DC power supply E2. As a result, charges accumulated near the interface between the cathode layer 21 and the gate layer 22 and the insulating wall portion 11 are canceled. As a result, field emission can be turned on and off at high speed. In this case, it is desirable that the cathode layer 21 and the gate layer 22 have mirror-symmetric shapes and the same film structure.

(1-4) Effects of the Field Emission Element of the Embodiment As described above, in the field emission element of the present embodiment, the upper end portion of the cathode layer 21 is linear in one direction parallel to the upper surface of the insulating substrate 10. Therefore, a large amount of electrons can be emitted from the linear field emission region which is the upper end portion of the cathode layer 21. Thereby, the brightness | luminance of a field emission element can be improved. Therefore, an FE lamp or FED capable of obtaining high luminance is realized.

Further, the cathode layer 21 having a uniform thickness can be easily formed on the side surface of the wall portion 11 by a general film forming technique such as vapor deposition. Thereby, the thickness t _C of the upper end portion of the cathode layer 21 extending linearly in one direction can be formed constant. In this case, since the upper end portion of the cathode layer 21 having a constant thickness t _C is unlikely to deteriorate with time, stable luminance can be obtained even when used for a long time. In addition, luminance flickering is also suppressed.

  Further, the wall portion 11, the cathode layer 21, and the gate layer 22 can be easily formed by ordinary photolithography, vapor deposition, or the like without performing high-temperature heat treatment. Therefore, various peripheral circuits including circuit elements such as TFTs (thin film transistors) can be easily formed in advance under the wall portion 11, the cathode layer 21 and the gate layer 22. Therefore, an active matrix FED or the like can be easily manufactured.

(2) Second Embodiment FIG. 5 is a schematic cross-sectional view of a field emission element according to a second embodiment of the present invention. FIG. 6 is an enlarged perspective view of a part of the field emission element of FIG.

  Also in this embodiment, the case where the field emission element is applied to a light source or a display device will be described.

  5 and 6, a plurality of insulating walls 11 extending in one direction are formed in parallel on the upper surface of the insulating substrate 10 at predetermined intervals.

  A cathode layer 21 having an L-shaped cross section is formed on a part of the upper surface of the insulating substrate 10 from one side surface of each wall portion 11. A cathode layer 21 having a bar-shaped cross section may be formed on one side surface of each wall portion 11.

  The cathode layer 21 formed on one side surface of one wall portion 11 serves as a set of electron emission sources. The cathode layers 21 formed on the adjacent wall portions 11 are separated from each other and electrically insulated.

  The structure of other parts of the field emission element of FIGS. 5 and 6 and the material of each part are the same as those of the field emission element of FIGS. 1 and 2.

  FIG. 7 is a schematic process cross-sectional view mainly showing a method of manufacturing the cathode layer 21 of the field emission device of FIGS.

  First, as shown in FIG. 7A, an insulating substrate 10 is prepared, and as shown in FIG. 7B, photoresists 51 are formed in stripes on the upper surface of the insulating substrate 10 at regular intervals by photolithography. Thereafter, a plurality of wall portions 11 are formed on the upper surface of the insulating substrate 10 in parallel with each other at regular intervals by etching.

  Next, as illustrated in FIG. 7C, the electrode layer 20 is formed by vapor deposition so as to cover the photoresist 51, one side surface of the wall portion 11, and the upper surface of the insulating substrate 10. In this case, vapor deposition is performed from diagonally above one side surface of the plurality of wall portions 11. Thereby, a thin electrode layer 20 is formed on one side surface of each wall portion 11 as compared with the upper surface of each wall portion 11 and the upper surface of insulating substrate 10.

  Next, as shown in FIG. 7D, the photoresist 51 is removed together with the electrode layer 20 thereon. Thereby, the cathode layer 21 is formed on one side surface of each wall portion 11 and a partial region of the upper surface of the insulating substrate 10 by a lift-off method.

  Next, the operation of the field emission device of FIGS. 5 and 6 will be described. FIG. 8 is a schematic diagram illustrating the operation principle of the field emission element of FIGS. 5 and 6.

  As shown in FIG. 8, the negative electrode and the positive electrode of the variable DC power source E1 are connected to the cathode layer 21 and the anode layer 40, respectively.

  When a DC voltage is applied between the anode layer 40 and the cathode layer 21 by the variable DC power supply E1, an electric field is concentrated near the upper end portion of the cathode layer 21 due to an edge effect, and electrons are generated from the upper end portion of the cathode layer 21. Radiated. In this case, since the upper end portion of the cathode layer 21 extends linearly in one direction parallel to the upper surface of the insulating substrate 10, the field emission region of the cathode layer 21 becomes linear, and a large amount of electrons are emitted.

  Electrons radiated from the upper end of the cathode layer 21 travel toward the anode layer 40 due to the electric field between the anode layer 40 and the cathode layer 21 and collide with the phosphor layer 30. Thereby, the phosphor layer 30 emits light.

  In this case, the amount of electrons reaching the phosphor layer 30 can be controlled by changing the DC voltage of the DC power supply E1. Thereby, the luminance of the field emission element can be controlled.

(3) Experiment of field emission from cathode layer Here, the following experiment was conducted to verify the field emission by the cathode layer 21 in the field emission element of the present embodiment.

  FIG. 9 is a schematic diagram showing a measurement circuit used in a field emission experiment.

  As shown in FIG. 9, the cathode layer 110 and the gate layer 120 were formed on the upper surface of the quartz glass substrate 100 with an interval of 50 μm. The cathode layer 110 and the gate layer 120 are a laminated film of a TiN (titanium nitride) film having a thickness of 15 nm and a Ti (titanium) film having a thickness of 1 nm.

  In addition, a collector electrode 130 made of Al (aluminum) is disposed above the quartz glass substrate 100 with an interval of 10 mm.

  A drive voltage Vd was applied between the gate layer 120 and the cathode layer 110, and a collector voltage Vc was applied between the collector electrode 130 and the cathode layer 110. The drive voltage Vd is constant at 100 V, the collector voltage Vc is gradually increased from 0 V to 260 V, the emission (field emission) current Ie from the cathode layer 110 to the collector electrode 130 and the cathode layer 110 to the gate layer 120 The drive current Id due to electrons was measured.

  FIG. 10 is a diagram showing measurement results of the emission current Ie and the drive current Id.

  In FIG. 10, the upward triangle mark “Δ” indicates the drive current Id [A], the downward triangle mark “▽” indicates the emission current Ie [A], and the square mark “◇” indicates the drive current Id and the emission current Ie. Is the sum [A].

  From the measurement result of FIG. 10, when the collector voltage Vc exceeds 100V, the emission current Ie due to field emission from the cathode layer 110 to the collector electrode 130 increases with the increase of the collector voltage Vc, and most of the electrons emitted in the field are It can be seen that it is collected by the collector electrode 130.

(4) Other Embodiments In the above embodiment, the field emission element according to the present invention is applied to a display device or a light source. However, the field emission element according to the present invention is an electron that functions in the atmosphere. It can also be applied to the source. In this case, the phosphor layer 30 shown in FIGS. 1 and 5 is unnecessary. Electrons radiated from the cathode layer 21 to the electric field reach the anode layer 40. Such an electron source can be used for food sterilization, anion generator, and the like.

  Moreover, in the said embodiment, although the several wall part 11 is formed in parallel so that it may extend in one direction on the upper surface of the insulating substrate 10, it is not limited to this. For example, the horizontal section of the plurality of wall portions 11 has a rectangular planar shape, the cathode layer 21 is formed on one or two of the four side surfaces, and the gate layer 22 is formed on the remaining one or two side surfaces. May be formed. Further, the horizontal cross section of the plurality of wall portions 11 has a triangular planar shape, and the cathode layer 21 is formed on one or two of the three side surfaces, and the gate layer 22 is formed on the remaining side surfaces. Good. Moreover, the horizontal cross section of the some wall part 11 may have another polygonal planar shape.

  Further, the horizontal cross section of the plurality of wall portions 11 has a circular or oval planar shape, the cathode layer 21 is formed in a partial region of the side surface, and the gate layer 22 is formed in the remaining partial region of the side surface. Also good.

  In the above embodiment, the side surfaces of the plurality of wall portions 11 are formed perpendicular to the upper surface of the insulating substrate 10, but the present invention is not limited to this, and the side surfaces of the plurality of wall portions 11 are formed on the upper surface of the insulating substrate 10. It may be formed so as to be inclined with respect to. That is, the vertical cross-sectional shape of the plurality of wall portions 11 is not limited to a rectangle, but may be a trapezoid.

  INDUSTRIAL APPLICABILITY The present invention can be used for FEDs used for illumination lamps, FE lamps used for backlights of liquid crystal displays, flat panel displays, and the like. Moreover, if this invention is used as an electron source which functions in air | atmosphere, it can utilize for the disinfection of a foodstuff, an anion generator, etc.

FIG. 1 is a schematic cross-sectional view of a field emission device according to a first embodiment of the present invention. FIG. 2 is an enlarged perspective view of a part of the field emission element of FIG. FIG. 3 is a schematic process cross-sectional view illustrating a method for manufacturing mainly the cathode layer and the gate layer of the field emission device of FIGS. 1 and 2. FIG. 4 is a schematic diagram illustrating the operation principle of the field emission element of FIGS. 1 and 2. FIG. 5 is a schematic cross-sectional view of a field emission element according to the second embodiment of the present invention. FIG. 6 is an enlarged perspective view of a part of the field emission element of FIG. FIG. 7 is a schematic process cross-sectional view mainly showing a method of manufacturing a cathode layer of the field emission device of FIGS. FIG. 8 is a schematic diagram illustrating the operation principle of the field emission element of FIGS. 5 and 6. FIG. 9 is a schematic diagram showing a measurement circuit used in a field emission experiment. FIG. 10 is a diagram showing the measurement results of the emission current and the drive current.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Insulating substrate 11 Wall part H Height 21,110 Cathode layer 22,120 Gate layer 21a, 22a Side part 21b, 22b Bottom part t, d Thickness 50 Transparent substrate 60 Support frame 30 Phosphor layer 40 Anode layer 51, 52 Photoresist 20 Electrode layer E1, E2 DC power supply 100 Quartz glass substrate 130 Collector electrode

Claims (7)

A substrate,
A plurality of insulating walls formed to have one side surface extending in a predetermined direction on the substrate;
A cathode layer formed on one side of each of the plurality of walls,
An electric field emission element comprising: an anode electrode disposed at a distance from the plurality of wall portions and an upper end portion of the cathode layer so as to face the substrate. The plurality of wall portions are formed to further have other side surfaces extending in a predetermined direction on the substrate,
2. The field emission device according to claim 1, further comprising gate layers respectively formed on the other side surfaces of the plurality of wall portions. The field emission element according to claim 1, further comprising a phosphor layer disposed between the plurality of walls and an upper end portion of the cathode layer and the anode electrode. Forming a plurality of insulating walls so as to have one side surface extending in a predetermined direction on the substrate;
Forming a cathode layer on one side of each of the plurality of walls,
And a step of disposing an anode electrode spaced from the plurality of wall portions and the upper end portion of the cathode layer so as to face the substrate. The step of forming the plurality of wall portions includes forming the plurality of wall portions so as to further include another side surface extending in a predetermined direction on the substrate,
The method of manufacturing a field emission element according to claim 4, further comprising forming a gate layer on each of the other side surfaces of the plurality of wall portions. 6. The method of manufacturing a field emission element according to claim 4, wherein the step of forming the cathode layer includes depositing a material of the cathode layer in an oblique direction with respect to one side surface of the plurality of wall portions. Method. 7. The method according to claim 4, further comprising a step of forming a phosphor layer disposed between the plurality of wall portions and an upper end portion of the cathode layer and the cathode layer. Manufacturing method of field emission element.

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