WO2006095947A1

WO2006095947A1 - Method of forming electron emitter tips using copper-carbon nanotube composite electroplating

Info

Publication number: WO2006095947A1
Application number: PCT/KR2005/002731
Authority: WO
Inventors: Woo-Yong Sung; Ho-Young Lee; Yong-Hyup Kim; Seung-Min Lee; Wal-Jun Kim; Sun-Chang Yeon
Original assignee: Seoul National University Industry Foundation
Priority date: 2005-03-11
Filing date: 2005-08-19
Publication date: 2006-09-14
Also published as: KR100656781B1; KR20060098225A

Abstract

Provided is a method of forming electron emitter tips for a field emission display device (FED) using copper-carbon nanotube composite electroplating. In the method, a cathode substrate having a surface on which a copper seed layer is defined is provided. The cathode substrate is dipped along with an anode substrate in an electroplating tank that is filled with an electroplating solution containing carbon nanotubes and a copper electrolytic solution. Thereafter, a copper-carbon nanotube composite is electroplated on the cathode substrate by supplying power to the cathode substrate and the anode substrate. By forming the electron emitter tips using the copper-carbon nanotube composite electroplating, an FED having a good adhesion of carbon nanotubes with the substrate can be fabricated. Also, the FED can have high luminance and a long lifetime and consume low power.

Description

METHOD OF FORMING ELECTRON EMITTER TIPS USING COPPER-CARBON NANOTUBE COMPOSITE ELECTROPLATING

Technical Field

[1] The present invention relates to a method of forming electron emitter tips, and more particularly, to a method of forming electron emitter tips using copper-carbon nanotube composite electroplating. Background Art

[2] A display device, such as a field emission display (FED), a vacuum fluorescent display (VFD), and a cathode ray tube (CRT), or a light source, such as a white light source and a backlight lamp for a liquid crystal display (LCD), requires electron emitter tips that emit electrons when an electric field is applied at constant intensity.

[3] An FED using electron emitter tips includes an upper substrate on which an anode coated with indium tin oxide (ITO) as a fluorescent material is formed and a lower substrate on which a cathode including the electron emitter tips is formed.

[4] In recent years, carbon nanotubes have attracted much attention as a new material for the electron emitter tips because they lower an electron emitting voltage by several ten times and elevate electron emitting current by several ten to several hundred times as compared with materials for conventional electron emitter tips. When the electron emitter tips are formed using carbon nanotubes, they should be formed to high degree of purity and high density at a low temperature. Also, end portions of the electron emitter tips should be as pointed as possible to facilitate electron emission. Disclosure of Invention Technical Problem

[5] A conventional method of forming electron emitter tips using carbon nanotubes includes printing a paste formed of a metal, an organic polymer, and carbon nanotubes on a lower substrate and forming a carbon nanotube layer by pattering the paste using a selective etching process. Alternatively, carbon nanotubes are dispersed along with an electrifier in a solvent and then electron emitter tips are formed using electrophoresis.

[6] However, when the paste is used, outgassing arises from the paste, not the carbon nanotubes, so that the lifetime of an emission device is shortened. Also, the carbon nanotubes that affect electron emission are undesirably dispersed, and adhesion of an electrode substrate to the carbon nanotubes is poor. As a result, uniform luminous efficiency cannot be obtained and the emission device cannot be employed for a long time. Also, in making use of electrophoresis, the carbon nanotubes are separated from a substrate due to weak adhesion at a high electric field. Therefore, a method of reinforcing adhesion of the carbon nanotubes to the substrate is needed for better practical use. Technical Solution

[7] The present invention provides a method of forming electron emitter tips using a carbon nanotube layer with high density and good adhesion to an electrode substrate, so that the electron emitter tips can have uniform luminance and a long lifetime.

[8] Also, the present invention provides a method of forming electron emitter tips to high density at such a low temperature as to prevent strain of a substrate.

[9] According to an aspect of the present invention, there is provided a method of forming electron emitter tips. In the method, a cathode substrate having a surface on which a copper seed layer is defined is provided. The cathode substrate is dipped along with an anode substrate in an electroplating tank that is filled with an electroplating solution containing carbon nanotubes and a copper electrolytic solution. Thereafter, a copper-carbon nanotube composite is electroplated on the cathode substrate by supplying power to the cathode substrate and the anode substrate.

[10] In the present invention, the copper electrolytic solution may be formed of copper sulfate, sulfuric acid, and hydrochloric acid. The power may be a pulse voltage, which is applied at a current density of 20 mA/cm or higher and at a frequency of 10 to 5,000 Hz. Also, electroplating the copper-carbon nanotube composite may be performed using copper ions contained in the copper electrolytic solution as a copper source.

[11] In the present invention, the electron emitter tips may be electron emitter tips for a field emission display (FED) or electron emitter tips for a field-emission-type backlight. Advantageous Effects

[12] According to the present invention, electron emitter tips are formed using copper- carbon nanotube composite electroplating, so that an FED having a good adhesion of a substrate with carbon nanotubes can be fabricated.

[13] Also, since an electroplating method is employed, outgassing, which is caused by an organic binder generated in a conventional paste method, can be solved.

[14] Further, an FED that has high luminance and a long lifetime and consumes low power can be fabricated. Brief Description of the Drawings

[15] FIG. 1 is a schematic diagram of an electroplating tank for copper-carbon nanotube composite electroplating according to the present invention;

[16] FIG. 2 is photographs of a copper-carbon nanotube composite electroplating structure according to an exemplary embodiment of the present invention; [17] FIGS. 3 and 4 are photographs of a copper-carbon nanotube composite electroplating structure according to another exemplary embodiment of the present invention; [18] FlG. 5 is photographs of a copper-carbon nanotube composite electroplating structure according to yet another exemplary embodiment of the present invention; [19] FlG. 6 is photographs of a copper-carbon nanotube composite electroplating structure according to further another exemplary embodiment of the present invention; [20] FIGS. 7 and 8 are photographs showing luminescent extent with respect to frequency characteristics of a copper-carbon nanotube composite electroplating structure according to exemplary embodiments of the present invention; [21] FIGS. 9 through 12 are cross sectional views illustrating a method of fabricating an

FED having a normal gate structure using electron emitter tips formed of carbon nanotubes and copper according to an exemplary embodiment of the present invention; [22] FIGS. 13 through 15 are cross sectional views illustrating a method of fabricating an FED having a normal gate structure using electron emitter tips according to another exemplary embodiment of the present invention; [23] FIGS. 16 through 19 are cross sectional views illustrating a method of fabricating an FED having a under gate structure using electron emitter tips according to an exemplary embodiment of the present invention; [24] FIGS. 20 and 21 are cross sectional views illustrating a method of fabricating a white light source using electron emitter tips according to an exemplary embodiment of the present invention; and [25] FIGS. 22 through 24 are cross sectional views illustrating a method of fabricating a white light source using electron emitter tips according to another exemplary embodiment of the present invention.

Best Mode for Carrying Out the Invention [26] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. In the drawings, the forms and thicknesses of layers may be exaggerated for clarity, and the same reference numerals are used to denote the same elements throughout the drawings. [27] FlG. 1 is a schematic diagram of an electroplating tank 1 for copper-carbon nanotube composite electroplating according to the present invention. [28] Referring to FlG. 1, an electroplating solution 15 is contained in the electroplating tank 1 to a predetermined water level, and an anode substrate 20 and a cathode substrate 25 on which electron emitter tips are formed are dipped in the electroplating solution 15. An electric field may be applied between the anode substrate 20 and the cathode substrate 25 by a power supplier 30. The anode substrate 20 may be a copper substrate as a copper source or formed of other metal such as tungsten. The cathode substrate 25 may be any substrate that is presently used, for example, a soda lime glass substrate or a silicon wafer, and is not restricted to a specific size. A seed layer required for electroplating may be formed on the cathode substrate 25 using a sputtering process, a thermal evaporation process, or an electrolytic plating process.

[29] The electroplating solution 15 may be a mixture of copper sulfate (90g/L), sulfuric acid (197g/L), and hydrochloric acid(0.1g/L) or a mixture of copper cyanide, sodium cyanide, and Rochelle salt, and carbon nanotubes are augmented to any one of the mixtures. The carbon nanotubes 35 each have a pointed shape with a diameter of several nm and stable thermal, chemical, and mechanical characteristics.

[30] Hereinafter, various exemplary methods of electroplating a copper-carbon nanotube composite using the electroplating tank 1 shown in FlG. 1 will be described.

[31] In the following embodiments, a direct current (DC) plating process and a pulse plating process were employed. In the case of the pulse plating process, a duty ratio, which refers to an on/off ratio, (for example, when the duty ratio is 20%, an on time is 20% and an off time is 80%) was 1 to 100%, and frequency was provided from low to high in the range of 10 to 5,000 Hz. Also, experiments were conducted under a current density of 20 to 100 mA/cm².

[32] In the present experiments, it could be confirmed that an electroplating result was affected by a lot of variables, such as stirring intensity, time, temperature, the density of a copper sulfate solution, current density, duty ratio for pulse plating, frequency, and use or disuse of a copper source for an anode substrate. Mode for the Invention

[33] Embodiment 1

[34] When a current density was 53 mA/cm and an electroplating solution was not stirred, an electroplating process was performed on an anode substrate using a copper source. A duty ratio was 33%, and a frequency of 100 Hz was used.

[35] FIG. 2 is photographs of a copper-carbon nanotube composite electroplating structure according to a first exemplary embodiment of the present invention.

[36] Referring to FIG. 2, when a current density was 50 mA/cm or higher, a carbon nanotube composite electroplating process was successfully performed. In electroplating at a high current density, when an anode (+) substrate was formed of a copper source, the resultant plating layer was formed like a typical copper plating thin layer, but carbon nanotubes did not have a pointed shape.

[37] [38] Embodiment 2

[39] When a current density was 53 mA/cm² and an electroplating solution was not stirred, an electroplating process was performed on an anode substrate without using a copper source. A duty ratio was 33%, and a frequency of 100 Hz was used. That is, the anode substrate was not formed of copper in comparison to the first embodiment.

[40] FIGS. 3 and 4 are photographs of a copper-carbon nanotube composite electroplating structure according to a second exemplary embodiment of the present invention.

[41] Referring to FIGS. 3 and 4, when a current density was 50 mA/cm or higher, a copper-carbon nanotube composite electroplating process was successfully performed. Without a copper source, a composite electroplating structure was different from the first embodiment in which the anode substrate including the copper source was electroplated at a high current density, and it can be seen that the copper-carbon nanotube composite electroplating structure was favorably obtained. In particular, when a pulse plating process was carried out at a high frequency, a plating thin layer improved in uniformity, and the mobility of carbon nanotubes in a copper sulfate solution further increased.

[42]

[43] Embodiment 3

[44] When a current density was 40 mA/cm and an electroplating solution was not stirred, an electroplating process was performed on an anode substrate using a copper source. A duty ratio was 33%, and a frequency of 100 Hz was used. That is, in the present embodiment, the anode substrate was formed of copper and the current density was lowered.

[45] FIG. 5 is photographs of a copper-carbon nanotube composite electroplating structure according to a third exemplary embodiment of the present invention.

[46] Referring to FIG. 5, when a current density was 40 mA/cm² and an anode substrate included a copper source, a structure similar to a typical copper plating thin layer was formed, and copper-carbon nanotube composite electroplating could not be found. In other words, it can be seen that when the anode substrate included the copper source, copper-carbon nanotube composite electroplating hardly occurred at a low current density.

[47]

[48] Embodiment 4

[49] When a current density was 40 mA/cm and an electroplating solution was not stirred, an electroplating process was performed on an anode substrate without using a copper source. A duty ratio was 33%, and a frequency of 100 Hz was used. That is, in the present embodiment, the anode substrate was not formed of copper and the current density was lowered.

[50] FlG. 6 is photographs of a copper-carbon nanotube composite electroplating structure according to a fourth exemplary embodiment of the present invention.

[51] Referring to FlG. 6, when a current density was 40 mA/cm² and the anode substrate included no copper source, a substrate that is different from a typical copper plating layer was formed, a copper-carbon nanotube composite electroplating structure was partially found. But, after a sufficient time elapsed, a copper-carbon nanotube composite was electroplated on the entire anode substrate.

[52]

[53] Embodiment 5

[54] When only a frequency characteristic was changed and other process conditions were held constant, a copper-carbon nanotube composite electroplating process was performed.

[55] FIGS. 7 and 8 are photographs showing luminescent extent with respect to frequency characteristics of a copper-carbon nanotube composite electroplating structure according to exemplary embodiments of the present invention. Specifically, FlG. 7 shows luminescent extent at a low frequency of about 100 Hz, and FlG.8 shows luminescent extent at a high frequency of about 1,000 Hz.

[56] Referring to FIGS. 7 and 8, it can be known that a copper-carbon nanotube composite was nonuniformly electroplated at a low frequency. During a copper-carbon nanotube electroplating process, edges of a substrate were electroplated more than other portions thereof due to a strong electric field. By comparison, a copper-carbon nanotube composite was uniformly electroplated at a high frequency. That is, an emission device including electroplated emitter tips emitted light uniformly under a high frequency condition.

[57] Hereinafter, a method of fabricating a display device or light source using electron emitter tips that are formed using copper-carbon nanotube composite electroplating according to exemplary embodiments of the present invention will be described. An FED and a white light source will be described as examples of the display device and the light source, respectively. However, it is obvious that the method of the present invention can be applied to other display devices or light sources.

[58] In general, the FED has a triode structure to easily control electron emission. The triode structure may be categorized into a under gate structure in which a gate electrode is disposed under a cathode electrode by interposing an insulating layer therebetween and a normal gate structure in which a gate electrode is disposed on a cathode electrode by interposing an insulating layer therebetween.

[59] FIGS. 9 through 12 are cross sectional views illustrating a method of fabricating an

FED having a normal gate structure using electron emitter tips formed of carbon nanotubes and copper according to an exemplary embodiment of the present invention.

[60] Referring to FlG. 9, a first insulating layer 110 is formed on a large-area lower substrate 100. The lower substrate 100 may be formed of glass, quartz, silicon, or alumina (Al O ). The first insulating layer 110 is formed to prevent interaction between the lower substrate 100 and a cathode electrode 200 that is formed in a subsequent process. The formation of the first insulating layer 110 may be omitted if required. The cathode electrode 200 may be formed of a chrome layer, a titanium layer, or a tungsten layer.

[61] Thereafter, a copper layer 300 is formed on the cathode electrode 200. The copper layer 300 is formed to a thickness of several to several hundred of nm, preferably, 400 to 500 nm, using a thermal evaporation process, an electronic beam (e-beam) evaporation process, or a sputtering process. After that, a second insulating layer 310 is formed on the copper layer 300, and a metal layer 320 for a gate electrode is formed on the second insulating layer 310. The metal layer 320 for the gate electrode is formed of chrome, titanium, or palladium using an e-beam evaporation process, a thermal evaporation process, or a sputtering process. Preferably, the first insulating layer 110, the cathode electrode 200, the copper layer 300, the second insulating layer 310, and the metal layer 320 for the gate electrode are formed at temperatures below a temperature at which the lower substrate 100 is strained.

[62] Referring to FlG. 10, a photoresist layer is coated on the metal layer 320 for the gate electrode, and a photoresist pattern PR is formed through photolithography and developing processes. After that, the metal layer 320 for the gate electrode is etched using the photoresist pattern PR as a mask, thereby forming a gate electrode 320a. The gate electrode 320a defines holes H, which expose the surface of the second insulating layer 310. The holes H may have a diameter of 0.8 to 5.0 μm and be arranged at an interval of 3.0 to 15.0 μm.

[63] Referring to FlG. 11, after the photoresist pattern PR is removed, the second insulating layer 310 is etched using the gate electrode 320a as an etch mask, thereby forming a second insulating layer pattern 310a. The surface of the copper layer 300 is exposed by the second insulating layer pattern 310a. In some cases, the photoresist pattern PR may not be removed and both the photoresist pattern PR and the gate electr ode 320a may be used as an etch mask to form the second insulating layer pattern 310a, and then the photoresist pattern PR may be removed.

[64] Subsequently, emitter tips 400 are formed on the resultant structure on which the second insulating layer pattern 310a is formed, using the above-described copper- carbon nanotube composite electroplating.

[65] Referring to FlG. 12, spacers 500 are formed on the gate electrode 320a.

[66] Thereafter, an anode electrode 700 is formed on an upper substrate 600 that is prepared beforehand, and a phosphor layer 800, which provokes emission of light, is attached onto the anode electrode 700. The phosphor layer 800 may be formed of red phosphor such as Y O S:Eu, Gd O :Eu, or Y O :Eu, green phosphor such as Gd O

2 2 2 3 2 3 2 2

S:Tb, SrGaS :Eu, ZnS :Cu, Cl, Y Al O :Tb, or Y SiO :Tb, or blue phosphor such as ZnS: Ag, Me, or Y SiO :Ce. The upper substrate 600 is formed of a transparent material, such as glass, to externally radiate light that is emitted from the phosphor layer 800. The anode electrode 700 is formed of a transparent material, such as indium tin oxide (ITO).

[67] Thereafter, the upper substrate 600 on which the anode electrode 700 and the phosphor layer 800 are attached is turned upside down and put on the spacers 500. The resultant structure is sealed in vacuum and encapsulated, thereby completing an FED. As a result, the phosphor layer 800 formed on the upper substrate 600 is spaced a predetermined distance apart from the electron emitter tips 400 by the spacers 500.

[68] In the completed FED, when a predetermined voltage (several tens of V) is applied between the gate electrode 320a and the cathode electrode 200, electrons are emitted from the electron emitter tips 400 formed of carbon nanotubes through quantum mechanical tunneling. The emitted electrons collide with the phosphor layer 800 due to a far higher voltage (several hundred to several thousand of V) that is applied to the anode electrode 700. Because of energy of the colliding electrons, electrons in the phosphor layer 800 are excited and dropped, thus generating light. The FED shown in FTG. 12 is a triode FED that includes the three electrodes 200, 320a, and 700. Of course, the method of the present invention can be applied also to a diode FED including two electrodes.

[69] FIGS. 13 through 15 are cross sectional views illustrating a method of fabricating an FED having a normal gate structure using electron emitter tips according to another exemplary embodiment of the present invention. Here, a description of the same forming methods and process conditions of components as in the first embodiment described with reference to FIGS. 9 through 12 will not be presented for brevity.

[70] Referring to FIG. 13, unlike in the first embodiment, a copper layer is not formed, and a cathode electrode 200, an insulating layer 310, a metal layer 320 for a gate electrode, and a photoresist pattern PR are sequentially formed on a large-area lower substrate 100. After that, the metal layer 320 for the gate electrode and the insulating layer 310 are sequentially etched using the photoresist pattern PR as an etch mask, thereby forming a gate electrode 320a and an insulating layer pattern 310a. As a result, the surface of the cathode electrode 200 is exposed.

[71] Referring to FIG. 14, a copper layer 300 is formed on the entire surface of the resultant structure of FIG. 13. As a result, the copper layer 300 is formed on the photoresist pattern PR and the cathode electrode 200. [72] Referring to FlG. 15, the photoresist pattern PR and the copper layer 300 deposited thereon are removed using a lift-off process, thereby leaving the copper layer 300 only on the cathode electrode 200. After that, electron emitter tips 400 are formed using the above-described copper-carbon nanotube composite electroplating. Subsequently, as described in the first embodiment, spacers are formed, an upper substrate on which an anode electrode and a phosphor layer are stacked is put on the spacers, and the resultant structure is sealed in vacuum and encapsulated, thereby completing an FED.

[73] FIGS. 16 through 19 are cross sectional views illustrating a method of fabricating an FED having a under gate structure using electron emitter tips according to an exemplary embodiment of the present invention. In the under gate structure, a cathode electrode is interposed between a gate electrode and a phosphor layer.

[74] Referring to FlG. 16, a gate electrode 325, an insulating layer 315, and a cathode electrode 305 are sequentially stacked on a large-area lower substrate 100.

[75] Referring to FlG. 17, a photoresist pattern PR is formed on the cathode electrode

305, and a cathode electrode 305a is patterned using the photoresist pattern PR as an etch mask.

[76] Referring to FlG. 18, after the photoresist pattern PR is removed, the insulating layer 315 is selectively etched using the patterned cathode electrode 305a as an etch mask until the gate electrode 325 is exposed. Although not shown in the drawings, the photoresist pattern PR, which is used to pattern the cathode electrode 305, may be used as an etch mask to form an insulating layer pattern 315a.

[77] Referring to FlG. 19, electron emitter tips 405 are formed on the patterned cathode electrode 305a using the above-described copper-carbon nanotube composite electroplating.

[78] Thereafter, spacers are formed, an upper substrate on which an anode electrode and a phosphor layer are stacked is put on the spacers, and the resultant structure is sealed in vacuum and encapsulated, thereby completing an FED.

[79] FIGS. 20 and 21 are cross sectional views illustrating a method of fabricating a white light source using electron emitter tips according to an exemplary embodiment of the present invention.

[80] Referring to FlG. 20, a cathode electrode 200 and a copper layer 300 are sequentially formed on a lower substrate 100. Next, electron emitter tips 400 are formed using copper-carbon nanotube composite electroplating. Thereafter, spacers 500 are formed on the copper layer 300 on which the electron emitter tips 400 are formed.

[81] Referring to FlG. 21, a transparent electrode 700 and a phosphor layer 800 are formed on an upper substrate 600, and the upper substrate 600 is put on the spacers 500 such that the surface of the phosphor layer 800 is disposed opposite the electron emitter tips 400. The phosphor layer 800 may be formed of a fluorescent material that provokes white emission, for example, a fluorescent material that provokes short- wavelength white emission, such as 3Ca (PO )CaFCl/Sb or Mn. After that, the

3 4 resultant structure is sealed in vacuum and encapsulated, thereby completing a white light source.

[82] In the completed white light source, when a predetermined voltage is applied between the cathode electrode 200 and the anode electrode 700, electrons are emitted from the electron emitter tips 400.

[83] FIGS. 22 through 24 are cross sectional views illustrating a method of fabricating a white light source using electron emitter tips according to another exemplary embodiment of the present invention. The present embodiment is different from the first embodiment as described with reference to FIGS. 20 and 21 in that electron emitter tips 400 are divided into groups, each group constituting one cell.

[84] Referring to FlG. 22, a first insulating layer 110, a cathode electrode 200, a copper layer 300, and a second insulating layer 310 are sequentially formed on a lower substrate 100 and selectively patterned using ordinary photolithography and etching processes, thereby forming a second insulating layer pattern 310a. The second insulating layer pattern 310a defines a plurality of holes H, which expose the underlying copper layer 300. In this case, the second insulating layer pattern 310a is formed such that each of the holes H has a diameter and interval appropriate for defining one cell.

[85] Referring to FlG. 23, electron emitter tips 400 are formed using the above- described copper-carbon nanotube composite electroplating on the copper layer 300 that is exposed by the holes H formed in the insulating layer pattern 350. Thereafter, spacers 500 are formed on the second insulating layer pattern 310a in which the electron emitter tips 400 are formed.

[86] Referring to FlG. 24, an upper substrate 600 on which an anode electrode 700 and a phosphor layer 800 are stacked is put on the spacers 500 such that the phosphor layer 800 is disposed opposite the electron emitter tips 400, and the resultant structure is sealed in vacuum and encapsulated, thereby completing a white light source. In this case, the phosphor layer 800 may be also patterned to expose portions of the transparent electrode 700 that are supported by the spacers 500.

[87] Although the present invention has been described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that a variety of modifications and variations may be made to the present invention without departing from the spirit or scope of the present invention defined in the appended claims, and their equivalents. Industrial Applicability [88] According to the present invention, electron emitter tips are formed using copper- carbon nanotube composite electroplating, so that an FED having a good adhesion of a substrate with carbon nanotubes can be fabricated.

[89] Also, since an electroplating method is employed, outgassing, which is caused by an organic binder generated in a conventional paste method, can be solved.

[90] Further, an FED that has high luminance and a long lifetime and consumes low power can be fabricated.

Claims

[1] A method of forming electron emitter tips comprising: providing a cathode substrate having a surface on which a copper seed layer is defined; dipping the cathode substrate along with an anode substrate in an electroplating tank that is filled with an electroplating solution containing carbon nanotubes and a copper electrolytic solution; and electroplating a copper-carbon nanotube composite on the cathode substrate by supplying power to the cathode substrate and the anode substrate. [2] The method according to claim 1, wherein the copper electrolytic solution is formed of copper sulfate, sulfuric acid, and hydrochloric acid. [3] The method according to claim 1, wherein electroplating the copper-carbon nanotube composite is performed using copper ions contained in the copper electrolytic solution as a copper source. [4] The method according to claim 1, wherein the power is a pulse voltage, which is applied at a current density of 20 mA/cm or higher and at a frequency of 10 to 5,000 Hz. [5] The method according to claim 4, wherein the power is a pulse voltage, wherein when the pulse voltage is applied at a current density of 20 mA/cm or higher, the amount of copper-carbon nanotube composite electroplating increases in time. [6] The method according to claim 1, wherein the electron emitter tips are electron emitter tips for a field emission display (FED). [7] The method according to claim 1, wherein the electron emitter tips are electron emitter tips for a field-emission-type backlight.