JP4082328B2 - Method for manufacturing electron-emitting device and method for manufacturing display device - Google Patents

Description

  The present invention relates to a method for manufacturing an electron-emitting device, and is particularly suitable for application to a method for manufacturing a display device including an electron-emitting device.

  When an electric field exceeding a certain threshold is applied to the surface of a conductor such as metal or semiconductor placed in a vacuum, electrons pass through the barrier due to the tunnel effect, and electrons are emitted into the vacuum even at room temperature. This phenomenon is called field emission, and an element that emits electrons by this phenomenon is called a field emission device. In recent years, FED (Field Emission Display) using a field emission type electron emission portion as an emitter has attracted attention. The FED is a flat display device (planar display device) including a display panel in which a large number of electron emission portions are formed on a cathode substrate by using a semiconductor processing technique or the like. In this FED, electrons are emitted by the concentration of an electric field from an electron emission portion that is electrically selected (addressed), and the electrons are collided with a phosphor on the anode substrate side, and an image is obtained by excitation and emission of the phosphor. it's shown.

  Some FEDs have a cone shape (conical shape) as an electron emission portion. Such an electron emitting portion is also called a Spindt-type emitter. In the manufacturing process of an FED employing a Spindt-type emitter, first, a cathode electrode, an insulating layer, and a gate electrode are formed on a substrate serving as a base of the cathode substrate, and then an opening is formed in the gate electrode and the insulating layer. A cone-shaped electron emission part is formed in the part.

  In forming the cone-shaped electron emission portion, a technique of vertically depositing a metal material from above the gate electrode is employed. At this time, a cone-shaped electron emission portion is formed in the opening portion of the insulating layer by deposition of vapor deposition metal, and at the same time, a metal material by vapor deposition is deposited on the gate electrode. Therefore, it is necessary to remove an unnecessary metal layer on the gate electrode after forming the electron emission portion. Therefore, in the prior art, a peeling layer is formed on the gate electrode in advance, and a metal material is deposited on the gate electrode to form a cone-shaped electron emission portion, and then an unnecessary metal layer is removed together with the peeling layer. (For example, refer to Patent Documents 1 and 2).

Japanese Patent No. 3094464 Japanese Patent No. 3116398

  However, in the above conventional method, it is necessary to form a peeling layer on the gate electrode by oblique vapor deposition of aluminum or the like before forming the electron emission portion by vapor deposition of a metal material, and this peeling layer is removed by wet etching or the like. In some cases, the metal layer stacked thereon floats without being dissolved in the etching solution, and may reattach to the substrate. Therefore, as another method, a method of directly depositing a metal material without forming a release layer on the gate electrode and then removing an unnecessary metal layer on the gate electrode by etching can be considered. Therefore, it is necessary to appropriately select etching conditions (such as an etchant and an etching temperature) so as to keep the etching rate low so that the electron emission portion is not etched together with the unnecessary metal layer. Therefore, it takes time to completely remove the unnecessary metal layer on the gate electrode.

  The present invention has been made to solve the above-described problems, and the object of the present invention is to produce an electron-emitting device having a Spindt-type emitter structure without forming a release layer on the gate electrode. An object of the present invention is to provide a method capable of quickly removing an unnecessary metal layer on a gate electrode after forming a cone-shaped electron emission portion by vapor deposition of a metal material.

The method for manufacturing an electron-emitting device according to the present invention includes forming a cathode electrode, an insulating layer, and a gate electrode on a substrate, and then forming an opening in the gate electrode and the insulating layer, thereby forming the cathode at the bottom of the opening. A first step of exposing the electrode ; a second step of forming a cone-shaped electron emission portion in the opening by vertically depositing a metal material from above the gate electrode ; and a gate electrode by depositing the metal material A third step of covering the electron emission portion with a protective material that has been impregnated into the metal layer having a columnar crystal structure laminated thereon and then dripped into the opening due to the penetration, and protecting the electron emission portion with the protective material And a fourth step of removing an unnecessary metal layer on the gate electrode by etching. Moreover, the manufacturing method of the display apparatus which concerns on this invention has a manufacturing process of the electron-emitting element containing the said 1st-4th process.

  In the method for manufacturing an electron-emitting device and the method for manufacturing a display device according to the present invention, after forming a cone-shaped electron-emitting portion in the opening by vapor deposition of a metal material on the gate electrode, the electron-emitting portion is covered with a protective material. Covering, and then removing the unnecessary metal layer on the gate electrode by etching while protecting the electron emitting portion with a protective material, even if the etching rate is increased by using an etching solution having a strong etching action, etc. It becomes possible to prevent etching of the electron emission portion.

  According to the present invention, when the unnecessary metal layer on the gate electrode is removed by etching, the etching of the electron emission portion is prevented by the protective material, so that the etching is performed by using an etching solution having a strong etching action. The rate can be increased. Thereby, even if a peeling layer is not formed on the gate electrode, an unnecessary metal layer on the gate electrode can be quickly removed by etching after forming a cone-shaped electron emission portion by vapor deposition of a metal material.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing the configuration of a display panel of an FED as an example of a display device to which the present invention is applied, and FIG. 2 is a perspective view showing the configuration of the display panel. In FIG. 1 and FIG. 2, a flat cathode substrate 1 and a flat anode substrate 2 are arranged in parallel and facing each other with a predetermined gap, and the two substrates 1, 2 are arranged. A panel structure (display panel) for displaying an image is formed by assembling them integrally with a rectangular frame 3 therebetween.

  A plurality of electron-emitting devices are formed on the cathode substrate 1. A large number of these electron-emitting devices are formed in a two-dimensional matrix in the effective area of the cathode substrate 1 (area that actually functions as a display portion). Each electron-emitting device includes an insulating support substrate (for example, a glass substrate) 4 serving as a base of the cathode substrate 1, a cathode electrode 5, an insulating layer 6, and a gate sequentially formed in a stacked state on the support substrate 4. The electrode 7 includes an opening 8 (8A, 8B) formed coaxially in the gate electrode 7 and the insulating layer 6, and an electron emission portion 9 formed in the opening 8.

  The cathode electrode 5 is formed in a stripe shape so as to form a plurality of cathode lines. The gate electrode 7 is formed in a stripe shape so as to form a plurality of gate lines intersecting (orthogonal) with each cathode line. The opening 8 is composed of a first opening 8A formed in the gate electrode 7 and a second opening 8B formed in the insulating layer 6 in communication with the first opening 8A. Yes. The electron emission portion 9 serves as an electron emission source (emitter), and has a so-called Spindt-type emitter structure in which a refractory metal such as molybdenum (Mo) is formed in a cone shape (conical shape).

  On the other hand, the anode substrate 2 includes a base transparent substrate (for example, a glass substrate) 12, a phosphor layer 13 and a black matrix 14 formed on the transparent substrate 12, and the phosphor layer 13 and the black matrix 14. An anode electrode 15 formed on the transparent substrate 12 in a covered state is provided. The phosphor layer 13 includes a phosphor layer 13R for red light emission, a phosphor layer 13G for green light emission, and a phosphor layer 13B for blue light emission. The black matrix 14 is formed between the phosphor layers 13R, 13G, and 13B for emitting each color. The anode electrode 15 is made of, for example, aluminum, and is formed in a laminated state over the entire effective region of the anode substrate 2 so as to face the electron emission portion of the cathode substrate 1.

  The cathode substrate 1 and the anode substrate 2 are bonded to each other at the outer peripheral portion (peripheral portion) via the frame 3. Further, a through-hole 16 for evacuation is provided in the ineffective area (area outside the effective area and not actually functioning as a display portion) of the cathode substrate 1. A tip tube 17 that is sealed after evacuation is connected to the through hole 16. However, since FIG. 1 shows the assembled state of the display device, the tip tube 17 is already sealed. Further, in FIGS. 1 and 2, the display of the vacuum pressure resistant spacers interposed in the gap portions between the substrates 1 and 2 is omitted.

  In the display device having the panel structure configured as described above, a relative negative voltage is applied to the cathode electrode 5 from the scanning circuit 18, a relative positive voltage is applied to the gate electrode 7 from the control circuit 19, and the anode electrode 15 A positive voltage higher than that of the gate electrode 7 is applied from the acceleration power supply 20. In such a display device, when an image is actually displayed, a scanning signal is input from the scanning circuit 18 to the cathode electrode 5, and a video signal is input from the control circuit 19 to the gate electrode 7.

  As a result, a voltage is applied between the cathode electrode 5 and the gate electrode 7, thereby concentrating the electric field on the sharpened portion of the electron emission portion 9, so that electrons penetrate the energy barrier by the quantum tunnel effect and the electron emission portion. 9 is released into the vacuum. The emitted electrons are attracted to the anode electrode 15 and move to the anode substrate 2 side, and collide with the phosphor layer 13 (13R, 13G, 13B) on the transparent substrate 12. As a result, since the phosphor layer 13 is excited by the collision of electrons and emits light, a desired image can be displayed on the display panel by controlling the light emission position in units of pixels.

  Next, a method for manufacturing a display device (FED) according to the present invention, in particular, a method for manufacturing an electron-emitting device will be described with reference to FIGS.

First, as shown in FIG. 3A, a cathode electrode 5, an insulating layer 6, and a gate electrode 7 are sequentially stacked on a support substrate 4 that serves as a base of the cathode substrate 1. The cathode electrode 5 is formed by depositing a low resistance metal material such as chromium (Cr) by sputtering. The insulating layer 6 is formed by depositing an insulating material such as silicon oxide (SiO ₂ ) by a CVD method. The gate electrode 7 is formed, for example, by depositing a low-resistance metal material such as chromium (Cr) by a sputtering method in the same manner as the cathode electrode 5.

  Next, an etching mask is formed on the gate electrode 7 by photolithography, and the gate electrode 7 is etched through the mask mask, whereby the first opening 8A is formed in the gate electrode 7 as shown in FIG. Form. Next, the insulating layer 6 is isotropically etched using the gate electrode 7 as an etching mask to insulate the second opening 8B having a diameter larger than that of the first opening 8A as shown in FIG. Layer 6 is formed. As a result, the opening 8 including the first opening 8A and the second opening 8B is formed in the gate electrode 7 and the insulating layer 6, and the cathode electrode 5 is exposed at the bottom of the opening 8. .

  Subsequently, a refractory metal material (for example, molybdenum) is vertically deposited on the gate electrode 7 to form a cone-shaped electron emission portion 9 in the opening 8 as shown in FIG. . In forming the electron emission portion 9, a refractory metal material is gradually laminated on the gate electrode 7. Therefore, at the stage where the cone-shaped electron emission portion 9 is obtained, the metal layer 10 made of a refractory metal material is formed on the gate electrode 7. Further, in the process of forming the metal layer 10, the space above the opening 8 is gradually narrowed by the refractory metal material, and finally the space above the opening 8 is almost closed. Therefore, the refractory metal material laminated on the cathode electrode 5 through the space above the opening 8 becomes a cone-shaped electron emission portion 9 with a sharp tip.

  Thereafter, as shown in FIG. 4A, the protective material 11 is supplied onto the metal layer 10 to cover the entire electron emission portion 9 in the opening 8 with the protective material 11. For the protective material 11, a material that is not etched with respect to etching described later (a material having etching resistance) is used. For example, a material obtained by diluting a resin material (resist or the like) based on a novolac resin with propylene glycol methyl ether (PGME) is used as the protective material 11.

  In this case, since the metal layer 10 formed by vapor deposition of the refractory metal material has a porous structure of columnar crystals, a low viscosity (for example, about 1 to 5 cP) made almost liquid is formed thereon. When the protective material 11 is supplied (applied) by a spin coat method or a spray method, the protective material 11 penetrates into the metal layer 10, and the protective material 11 hangs down from the space above the opening 8 to the electron emission portion 9 due to this penetration. . Therefore, even if the space above the opening 8 is closed by the metal layer 10, the electron emission portion 9 can be covered with the protective material 11.

  At that time, with the protective material 11 applied on the metal layer 10, for example, the entire support substrate 4 is placed in a pressure vessel and exposed to an atmosphere higher than atmospheric pressure, or from the metal layer 10 side to the support substrate 4 side. When the protective material 11 is pressed from the outside of the support substrate 4 by rotating the entire support substrate 4 so that centrifugal force is applied to the metal layer 10, the penetration of the protective material 11 into the metal layer 10 can be promoted. Therefore, the electron emission part 9 can be quickly covered with the protective material 11.

  Subsequently, as shown in FIG. 4 (B), other unnecessary protective material 11 (which remains on or inside the metal layer 10) except for the protective material 11 covering the electron emission portion 9, The protective material 11) that does not contribute to the coating of the electron emission portion 9 is removed by, for example, dry ashing using oxygen plasma. At this time, since the space above the opening 8 is closed by the metal layer 10, the protective material 11 covering the electron emission portion 9 is not removed by ashing. Therefore, only the unnecessary protective material 11 can be selectively removed.

  Next, as shown in FIG. 4C, the unnecessary metal layer 10 on the gate electrode 7 is removed by etching while protecting the electron emission portion 9 with a protective material 11. In this etching, the entire support substrate 4 as a sample is immersed in an etching solution, thereby removing the metal layer 11 made of a refractory metal material and opening the space above the opening 8. As the etching solution, a solution having a strong etching action on a high-melting point metal material such as molybdenum to be etched, for example, a nitric acid solution, an acetic acid solution, a phosphoric acid solution, a hydrogen peroxide solution, or the like can be used.

  In this case, since the electron emission portion 9 is covered and protected by the protective material 11 having resistance to etching, only the unnecessary metal layer 11 on the gate electrode 7 can be selectively removed by etching. . Further, by protecting the electron emission portion 9 with the protective material 11, a high etching rate can be applied by using an etching solution that exhibits a strong etching action or by setting the etching temperature high. Therefore, the unnecessary metal layer 11 on the gate electrode 7 can be quickly removed by etching.

Subsequently, by immersing the entire support substrate 4 in an organic solvent capable of dissolving the protective material 11, the protective material 11 that had previously covered the electron emission portion 9 is made organic as shown in FIG. Dissolve and remove with solvent. As the organic solvent, for example, a CH ₃ COCH ₃ (product name: acetone) solution can be used. By dissolving and removing the protective material 11 with this organic solvent, the cone-shaped electron emission portion 9 made of a refractory metal is exposed in the opening 8.

  A plurality of electron-emitting devices are formed on the cathode substrate 1 in accordance with the manufacturing process as described above. Further, the cathode substrate 1 obtained in this way is bonded to an separately manufactured anode substrate 2 through a frame 3 and a spacer (not shown). As a result, an FED display panel which is a flat display device is obtained.

It is sectional drawing which shows the structure of the display panel of FED as an example of the display apparatus with which this invention is applied. It is a perspective view which shows the structure of the display panel of FED as an example of the display apparatus with which this invention is applied. It is process drawing (the 1) which shows the manufacturing method of the electron emission element which concerns on embodiment of this invention. It is process drawing (the 2) which shows the manufacturing method of the electron emission element which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cathode substrate, 2 ... Anode substrate, 5 ... Cathode electrode, 6 ... Insulating layer, 7 ... Gate electrode, 8 ... Opening part, 9 ... Electron emission part, 10 ... Metal layer, 11 ... Protective material

Claims (8)

Forming a cathode electrode, an insulating layer and a gate electrode on a substrate, and then forming an opening in the gate electrode and the insulating layer, thereby exposing the cathode electrode to the bottom of the opening ;
A second step of forming a cone-shaped electron emission portion in the opening by vertically depositing a metal material on the gate electrode;
A metal material having a columnar crystal structure laminated on the gate electrode by vapor deposition of the metal material is infiltrated with a protective material, and the electron emitting portion is covered with the protective material dripping into the opening due to the infiltration. Process,
And a fourth step of removing an unnecessary metal layer on the gate electrode by etching while protecting the electron-emitting portion with the protective material. The method for manufacturing an electron-emitting device according to claim 1, further comprising a step of removing an unnecessary protective material that does not contribute to the coating of the electron-emitting portion after the third step. The method of manufacturing an electron-emitting device according to claim 1, wherein, in the fourth step, a nitric acid solution, an acetic acid solution, a phosphoric acid solution, or a hydrogen peroxide solution is used as an etching solution for etching. The method of manufacturing an electron-emitting device according to claim 1, further comprising a step of removing the protective material protecting the electron-emitting portion after the fourth step. In the third step, it supplies the protective material on the metal layer which is laminated on the gate electrode, the protective material by pressurization of claim 1, wherein the impregnated the metal layer A method for manufacturing an electron-emitting device. The method for manufacturing an electron-emitting device according to claim 2 , wherein the unnecessary protective material is removed by ashing after the third step. The method for manufacturing an electron-emitting device according to claim 4 , wherein the protective material is dissolved and removed with an organic solvent after the fourth step. Forming a cathode electrode, an insulating layer and a gate electrode on a substrate, and then forming an opening in the gate electrode and the insulating layer, thereby exposing the cathode electrode to the bottom of the opening ;
A second step of forming a cone-shaped electron emission portion in the opening by vertically depositing a metal material on the gate electrode;
A metal material having a columnar crystal structure laminated on the gate electrode by vapor deposition of the metal material is infiltrated with a protective material, and the electron emitting portion is covered with the protective material dripping into the opening due to the infiltration. Process,
And a fourth step of removing an unnecessary metal layer on the gate electrode by etching while protecting the electron-emitting portion with the protective material. Manufacturing of a display device, comprising: Method.

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