Abstract:
A method of forming emitters and a method of manufacturing a Field Emission Device (FED) using the method includes: forming a volume-changeable structure on an electrode, the volume-changeable structure composed of a polymer which reversibly swells and shrinks in response to an external stimulus; injecting an electron-emitting material into the volume-changeable structure; aligning the electron-emitting material; and removing the polymer to form the emitters.

Description:
CLAIM OF PRIORITY  
       [0001]     This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. § 119 from an application for METHOD OF FORMING EMITTERS AND METHOD OF MANUFACTURING FIELD EMISSION DEVICE earlier filed in the Korean Intellectual Property Office on 10 Aug. 2004 and there duly assigned Ser. No. 10-2004-0062774.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a method of forming emitters and a method of manufacturing a Field Emission Device (FED), and more particularly, to a method of forming emitters at a low temperature that can be applied to a complicated structure and a method of manufacturing an FED.  
         [0004]     2. Description of the Related Art  
         [0005]     FEDs are devices that emit electrons from emitters formed on a cathode electrode by applying a strong electric field between the cathode electrode and a gate electrode. Recently, carbon nano-tube emitters which use Carbon Nano-Tubes (CNTs) as an electron-emitting material are primarily used as electron-emitters in the FEDs.  
         [0006]     Methods of forming carbon nano-tube emitters include a method of growing CNTs directly on a substrate and a method of making CNTs from a paste.  
         [0007]     However, in the former method, since CNTs are grown directly on the substrate, it is difficult to manufacture a large FED. In addition, the method requires a high temperature, and thus, the use of a glass substrate can cause a problem. The latter method requires an additional process of aligning CNTs, and accordingly, the CNTs can only be applied with difficultly to a complicated structure.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention provides a method of forming emitters at a low temperature that can be applied to a complicated structure.  
         [0009]     The present invention also provides a method of manufacturing a Field Emission Device (FED) using the method of forming emitters.  
         [0010]     According to one aspect of the present invention, a method of forming emitters is provided, the method comprising: forming a volume-changeable structure on an electrode, the volume-changeable structure including a polymer which reversibly swells and shrinks in response to an external stimulus; injecting an electron-emitting material into the volume-changeable structure; aligning the electron-emitting material; and removing the polymer to form the emitters.  
         [0011]     Forming the volume-changeable structure preferably comprises coating the polymer on a substrate and the electrode formed on the substrate and patterning the polymer.  
         [0012]     Forming the volume-changeable structure preferably further comprises removing water from the patterned polymer.  
         [0013]     The polymer preferably comprises an Electro-Active Polymer (EAP) or a hydrogel.  
         [0014]     The polymer preferably comprises at least one polymer selected from the group consisting of PDMS, PMA, PAA, PNIPAAm, PAM, HA, AL, PVA, PDADMAC, SA, AAm, NIPAAm, PVME, PEG, PPG, MC, PDEAEM, glucose, chitosan, and gelatin.  
         [0015]     Injecting the electron-emitting material into the volume-changeable structure preferably comprises repeatedly swelling and shrinking the volume-changeable structure.  
         [0016]     Repeatedly swelling and shrinking the volume-changeable structure preferably comprises placing the volume-changeable structure in a first aqueous solution including the electron-emitting material and repeatedly applying an external stimulus to the volume-changeable structure and removing the external stimulus from the volume-changeable structure.  
         [0017]     The external stimulus preferably comprises at least one stimulus selected from the group consisting of a temperature, a pH, an electric field, and light.  
         [0018]     The electron-emitting material preferably comprises at least one material selected from the group consisting of Carbon Nano-Tubes (CNTs), amorphous carbon, nano-diamonds, metal nano-wires, and metal oxide nano-wires.  
         [0019]     The first aqueous solution preferably further comprises conductive nano-particles for supporting the electron-emitting material on the electrode, the conductive nano-particles being injected into the volume-changeable structure together with the electron-emitting material.  
         [0020]     Aligning the electron-emitting material preferably comprises swelling the volume-changeable structure.  
         [0021]     Swelling the volume-changeable structure preferably comprises placing the volume-changeable structure in a second aqueous solution, and applying an external stimulus to the volume-changeable structure and removing the applied external stimulus from the volume-changeable structure.  
         [0022]     The external stimulus preferably comprises at least one stimulus selected from the group consisting of a temperature, a pH, an electric field, and light.  
         [0023]     Removing the polymer preferably comprises heating or a plasma treatment.  
         [0024]     According to another aspect of the present invention, a method of forming emitters is provided, the method comprising: forming a volume-changeable structure on an electrode, the volume-changeable structure comprising an electron-emitting material and a polymer which reversibly swells and shrinks in response to an external stimulus; aligning the electron-emitting material; and removing the polymer to form the emitters.  
         [0025]     Forming the volume-changeable structure preferably comprises coating the polymer on a substrate and the electrode formed on the substrate and patterning the polymer.  
         [0026]     Forming the volume-changeable structure preferably further comprises removing water from the patterned polymer.  
         [0027]     The electron-emitting material preferably comprises at least one material selected from the group consisting of CNTs, amorphous carbon, nano-diamonds, metal nano-wires, and metal oxide nano-wires.  
         [0028]     The polymer preferably comprises an EAP or a hydrogel.  
         [0029]     The polymer preferably comprises at least one polymer selected from the group consisting of PDMS, PMA, PAA, PNIPAAm, PAM, HA, AL, PVA, PDADMAC, SA, AAm, NIPAAm, PVME, PEG, PPG, MC, PDEAEM, glucose, chitosan, and gelatin.  
         [0030]     The volume-changeable structure preferably further comprises conductive nano-particles for supporting the electron-emitting material on the electrode.  
         [0031]     Aligning the electron-emitting material preferably comprises swelling the volume-changeable structure.  
         [0032]     Swelling the volume-changeable structure preferably comprises placing the volume-changeable structure in an aqueous solution, and applying an external stimulus to the volume-changeable structure and removing the applied external stimulus from the volume-changeable structure.  
         [0033]     The external stimulus preferably comprises at least one stimulus selected from the group consisting of a temperature, a pH, an electric field, and light.  
         [0034]     Removing the polymer preferably comprises heating or a plasma treatment.  
         [0035]     According to still another aspect of the present invention, a method of manufacturing a Field Emission Device (FED) is provided, the method comprising: forming a cathode electrode, an insulating layer, and a gate electrode sequentially on a substrate and forming an emitter aperture exposing a portion of the cathode electrode in the insulating layer; forming a volume-changeable structure in the emitter aperture, the volume-changeable structure comprising a polymer which reversibly swells and shrinks in response to an external stimulus; injecting an electron-emitting material into the volume-changeable structure; aligning the electron-emitting material; and removing the polymer to form emitters.  
         [0036]     Forming the volume-changeable structure preferably comprises: coating a photoresist on the gate electrode and the cathode electrode and patterning the photoresist to expose a portion of the cathode electrode; coating the polymer on the photoresist and the top surface of the exposed cathode electrode; patterning the polymer with a photo-lithographic process by a back-side exposure using the photoresist as a photo-mask; and removing the photoresist.  
         [0037]     Forming the volume-changeable structure further preferably comprises removing water from the patterned polymer.  
         [0038]     The polymer preferably comprises an EAP or a hydrogel.  
         [0039]     The polymer preferably comprises at least one polymer selected from the group consisting of PDMS, PMA, PAA, PNIPAAm, PAM, HA, AL, PVA, PDADMAC, SA, AAm, NIPAAm, PVME, PEG, PPG, MC, PDEAEM, glucose, chitosan, and gelatin.  
         [0040]     Injecting the electron-emitting material into the volume-changeable structure preferably comprises repeatedly swelling and shrinking the volume-changeable structure.  
         [0041]     Repeatedly swelling and shrinking the volume-changeable structure preferably comprises placing the volume-changeable structure in a first aqueous solution including the electron-emitting material and repeatedly applying the external stimulus to the volume-changeable structure and removing the external stimulus from the volume-changeable structure.  
         [0042]     The external stimulus preferably comprises at least one stimulus selected from the group consisting of a temperature, a pH, an electric field, and light.  
         [0043]     The electron-emitting material preferably comprises at least one electron-emitting material selected from the group consisting of CNTs, amorphous carbon, nano-diamonds, metal nano-wires, and metal oxide nano-wires.  
         [0044]     The first aqueous solution preferably further comprises conductive nano-particles for supporting the electron-emitting material on the cathode electrode, the conductive nano-particles being injected into the volume-changeable structure together with the electron-emitting material.  
         [0045]     Aligning the electron-emitting material preferably comprises swelling the volume-changeable structure.  
         [0046]     Swelling the volume-changeable structure preferably comprises placing the volume-changeable structure in which the electron-emitting material has been injected in a second aqueous solution, and applying an external stimulus to the volume-changeable structure and removing the applied external stimulus from the volume-changeable structure.  
         [0047]     The external stimulus preferably comprises at least one stimulus selected from the group consisting of a temperature, a pH, an electric field, and light.  
         [0048]     Removing the polymer preferably comprises heating or a plasma treatment.  
         [0049]     According to still another aspect of the present invention, a method of manufacturing a Field Emission Device (FED) is provided, the method comprising: forming a cathode electrode, an insulating layer, and a gate electrode sequentially on a substrate and forming an emitter aperture exposing a portion of the cathode electrode in the insulating layer; forming a volume-changeable structure comprising an electron-emitting material and a polymer which reversibly swells and shrinks in response to an external stimulus in the emitter aperture; aligning the electron-emitting material; and removing the polymer to form emitters.  
         [0050]     Forming the volume-changeable structure preferably comprises: coating a photoresist on the gate electrode and the cathode electrode and patterning the photoresist to expose a portion of the cathode electrode; coating the polymer containing the electron-emitting material on the photoresist and the top surface of the exposed cathode electrode; patterning the polymer using a photolithographic process by a back-side exposure using the photoresist as a photomask; and removing the photoresist.  
         [0051]     Forming the volume-changeable structure preferably further comprises removing water from the patterned polymer.  
         [0052]     The electron-emitting material preferably comprises at least one material selected from the group consisting of CNTs, amorphous carbon, nano-diamonds, metal nano-wires, and metal oxide nano-wires.  
         [0053]     The polymer preferably comprises an EAP or a hydrogel.  
         [0054]     The polymer preferably comprises at least one polymer selected from the group consisting of PDMS, PMA, PAA, PNIPAAm, PAM, HA, AL, PVA, PDADMAC, SA, AAm, NIPAAm, PVME, PEG, PPG, MC, PDEAEM, glucose, chitosan, and gelatin.  
         [0055]     The volume-changeable structure preferably further comprises conductive nano-particles for supporting the electron-emitting material on the cathode electrode.  
         [0056]     Aligning the electron-emitting material preferably comprises swelling the volume-changeable structure.  
         [0057]     Swelling the volume-changeable structure preferably comprises placing the volume-changeable structure in an aqueous solution, and applying an external stimulus to the volume-changeable structure and removing the applied external stimulus from the volume-changeable structure.  
         [0058]     The external stimulus preferably comprises at least one stimulus selected from the group consisting of a temperature, a pH, an electric field, and light.  
         [0059]     Removing the polymer preferably comprises heating or a plasma treatment. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0060]     A more complete appreciation of the present invention, and many of the attendant advantages thereof, will be readily apparent as the present invention becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:  
         [0061]      FIGS. 1A through 1F  are views of a method of forming emitters according to an embodiment of the present invention;  
         [0062]      FIGS. 2A through 2E  are views of a method of forming emitters according to another embodiment of the present invention;  
         [0063]      FIGS. 3A through 3G  are views of a method of manufacturing a Field Emission Device (FED) according to an embodiment of the present invention; and  
         [0064]      FIGS. 4A through 4F  are views of a method of manufacturing an FED according to another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0065]     Hereinafter, the present invention is described in more detail with reference to the following examples. Throughout the drawings, like reference numerals refer to like elements.  
         [0066]      FIGS. 1A through 1F  are views of a method of forming emitters according to an embodiment of the present invention.  
         [0067]     Referring to  FIG. 1A , a predetermined polymer  120 ′ is coated on a substrate  100  and an electrode  110  is formed on the substrate  100 . The polymer  120 ′ is a material which reversibly swells and shrinks in response to an external stimulus, such as an Electro-Active Polymer (EAP) and a hydrogel. Specifically, the polymer  120 ′ can be composed of at least one polymer selected from the group consisting of PDMS (poly(dimethylsiloxane)), PMA (poly(methacrylic acid)), PAA (poly(acrylic acid)), PNIPAAm (poly(N-isopropylacrylamide)), PAM (polyarylamide), HA (hyaluronic acid), AL (alginate), PVA (polyvinylalchol), PDADMAC (poly(diallyldimethylammonium chloride)), SA (sodium alginate), AAm (acrylamide), NIPAAm (N-isopropylacrylamide), PVME (poly(vinyl methyl ether)), PEG (poly(ethylene glycol)), PPG (poly(propylene glycol), MC (methylcellulose), PDEAEM (poly(N,N-ethylaminoethyl methacrylate), glucose, chitosan, and gelatin.  
         [0068]     Then, as illustrated in  FIG. 1B , the polymer  120 ′ coated on the substrate  100  is patterned. Next, as illustrated in  FIG. 1C , when water is removed from the patterned polymer  120 ′, a volume-changeable structure  130  composed of a polymer  120  which reversibly swells and shrinks in response to an external stimulus is formed on the top surface of the electrode  110 . Alternatively, the volume-changeable structure  130  can be composed of a polymer which is formed by electro-polymerization on the substrate  100  and the electrode  110  formed on the substrate  100 .  
         [0069]     Referring to  FIG. 1D , the resultant product illustrated in  FIG. 1C  is placed into a first aqueous solution  160  contained in a first container  150 . An electron-emitting material  141  and conductive nano-particles  142  are dispersed in the first aqueous solution  160 . The electron-emitting material  141  can be composed of at least one material selected from the group consisting of Carbon Nano-Tubes (CNTs), amorphous carbon, nano-diamonds, metal nano-wires, and metal oxide nano-wires. The conductive nano-particles  142  are used to support the electron-emitting material  141  on the electrode  110  and are primarily composed of nano-metal particles. When the external stimulus is repeatedly applied to and removed from the volume-changeable structure  130 , with the volume-changeable structure  130  being immersed in the first aqueous solution  160 , the volume-changeable structure  130  repeatedly swells and shrinks. Thus, the electron-emitting material  141  and the conductive nano-particles  142  dispersed in the first aqueous solution  160  are injected into the volume-changeable structure  130 . The external stimulus can be at least one stimulus selected from the group consisting of a temperature, a pH, an electric field, and light.  
         [0070]     Referring to  FIG. 1E , the resultant product illustrated in  FIG. 1D  is placed into a second aqueous solution  180  contained in a second container  170 . The second aqueous solution  180  contains neither the electron-emitting material  141  nor the conductive nano-particles  142 . When applying an external stimulus to the volume-changeable structure  130  or removing the applied external stimulus from the volume-changeable structure  130 , with the volume-changeable structure  130  being immersed in the second aqueous solution  180 , the volume-changeable structure  130  swells. Accordingly, the electron-emitting material  141  in the volume-changeable structure  130  is aligned substantially perpendicular to a surface of the  8  electrode  110 . The electron-emitting material  141  is supported on the electrode  110  by the conductive nano-particles  142 . The external stimulus can be at least one stimulus selected from the group consisting of a temperature, a pH, an electric field, and light.  
         [0071]     Then, when the polymer  120  is removed from the resultant product illustrated in  FIG. 1E , the emitters  140  which are composed of the electron-emitting material  141  and the conductive nano-particles  142  are obtained, as illustrated in  FIG. 1F . The polymer  120  can be removed by heating or a plasma treatment, for example.  
         [0072]      FIGS. 2A through 2E  are views illustrating a method of forming emitters according to another embodiment of the present invention.  
         [0073]     Referring to  FIG. 2A , a predetermined polymer  220 ′ containing an electron-emitting material  241  and conductive nano-particles  242  is coated on a substrate  200  and an electrode  210  formed on the substrate  200 . The electron-emitting material  241  can be composed of at least one material selected from the group consisting of CNTs, amorphous carbon, nano-diamonds, metal nano-wires, and metal oxide nano-wires. The conductive nano-particles  242  can be primarily composed of nano-metal particles. The polymer  220 ′ is a material which reversibly swells and shrinks in response to an external stimulus, such as an EAP or a hydrogel. Specifically, the polymer  220 ′ can be composed of at least one polymer selected from the group consisting of PDMS, PMA, PAA, PNIPAAm, PAM, HA, AL, PVA, PDADMAC, SA, AAm, NIPAAm, PVME, PEG, PPG, MC, PDEAEM, glucose, chitosan, and gelatin.  
         [0074]     Then, as illustrated in  FIG. 2B , the polymer  220 ′ is patterned. Next, as illustrated in  FIG. 2C , when water is removed from the patterned polymer  220 ′, a volume-changeable structure  230  composed of the electron-emitting material  241 , the conductive nano-particles  242 , and a polymer  220  which reversibly swells and shrinks in response to an external stimulus is formed on the top surface of the electrode  210 . Alternatively, the volume-changeable structure  230  can be composed of a polymer containing the electron-emitting material  241  and the conductive nano-particles  242 , which is formed by electro-polymerization on the substrate  200  and the electrode  210  formed on the substrate  200 .  
         [0075]     Referring to  FIG. 2D , the resultant product illustrated in  FIG. 2C  is placed into an aqueous solution  280  contained in a container  270 . The aqueous solution  280  contains neither the electron-emitting material  241  nor the conductive nano-particles  242 . When applying an external stimulus to the volume-changeable structure  230  or removing the applied external stimulus from the volume-changeable structure  230 , with the volume-changeable structure  230  being immersed in the aqueous solution  280 , the volume-changeable structure  230  swells. Accordingly, the electron-emitting material  241  in the volume-changeable structure  230  is aligned substantially perpendicular to a surface of the electrode  210 . The electron-emitting material  241  is supported on the electrode  210  by the conductive nano-particles  242 . The external stimulus can be at least one stimulus selected from the group consisting of a temperature, a pH, an electric field, and light.  
         [0076]     Then, when the polymer  220  is removed from the resultant product illustrated in  FIG. 2D , the emitters  240  which are composed of the electron-emitting material  241  and the conductive nano-particles  242  are obtained, as illustrated in  FIG. 2E . The polymer  220  can be removed by heating or plasma treatment, for example.  
         [0077]     Hereinafter, a method of manufacturing an FED using the method of forming emitters according to embodiments of the present invention are described.  
         [0078]      FIGS. 3A through 3G  are views of a method of manufacturing an FED according to an embodiment of the present invention.  
         [0079]     Referring to  FIG. 3A , a cathode electrode  310 , an insulating layer  312 , and a gate electrode  314  are sequentially formed on a substrate  300  and an emitter aperture  315  exposing a portion of the cathode electrode  310  is formed in the insulating layer  312 . The substrate  300  can generally be composed of glass. The cathode electrode  310  can be composed of Indium Tin Oxide (ITO), which is a conductive transparent material. The gate electrode  314  can be composed of a conductive metal, for example, chromium (Cr).  
         [0080]     Specifically, a cathode electrode layer which is composed of ITO is deposited on the substrate  300  to a predetermined thickness and then patterned into a predetermined pattern, for example, in the form of stripes, to obtain the cathode electrode  310 . Then, the insulating layer  312  is formed on the entire surfaces of the cathode electrode  310  and the substrate  300  to a predetermined thickness. Subsequently, a gate electrode layer is formed on the insulating layer  312 . The gate electrode layer is formed by depositing a conductive metal by sputtering. The gate electrode layer is patterned to a predetermined pattern to obtain the gate electrode  314 . Then, an exposed portion of the insulating layer  312  through the gate electrode  314  is etched, thereby forming the emitter aperture  315  which exposes a portion of the cathode electrode  310 .  
         [0081]     Referring to  FIG. 3B , a photoresist  316  is formed on the entire surface of the resultant product illustrated in  FIG. 3A  to a predetermined thickness and patterned to expose a portion of the cathode electrode  310 . Then, a predetermined polymer  320 ′ is coated on the photoresist  316  and the exposed portion of the cathode electrode  310 . The polymer  320 ′ is a material which reversibly swells and shrinks in response to an external stimulus, such as an EAP or a hydrogel. Specifically, the polymer  320 ′ can be composed of at least one polymer selected from the group consisting of PDMS, PMA, PAA, PNIPAAm, PAM, HA, AL, PVA, PDADMAC, SA, AAm, NIPAAm, PVME, PEG, PPG, MC, PDEAEM, glucose, chitosan, and gelatin.  
         [0082]     Referring to  FIG. 3C , the polymer  320 ′ is patterned using a photolithographic process by a back-side exposure in which the photoresist  316  is used as a photomask, and then, the photoresist  316  is removed. Referring to  FIG. 3D , when water is removed from the polymer  320 ′, a volume-changeable structure  330  composed of a polymer  320  which reversibly swells and shrinks in response to an external stimulus is formed in the emitter aperture  315 .  
         [0083]     Referring to  FIG. 3E , the resultant product illustrated in  FIG. 3D  is placed into a first aqueous solution  360  contained in a first container  350 . An electron-emitting material  341  and conductive nano-particles  342  are dispersed in the first aqueous solution  360 . The electron-emitting material  341  can be composed of at least one material selected from the group consisting of CNTs, amorphous carbon, nano-diamonds, metal nano-wires, and metal oxide nano-wires. The conductive nano-particles  342  are used to support the electron-emitting material  341  on the electrode  310  and are primarily composed of nano-metal particles. When the external stimulus is repeatedly applied to and removed from the volume-changeable structure  330 , the volume-changeable structure  330  being immersed in the first aqueous solution  360 , the volume-changeable structure  330  repeatedly swells and shrinks. Thus, the electron-emitting material  341  and the conductive nano-particles  342  dispersed in the first aqueous solution  360  are injected into the volume-changeable structure  330 . The external stimulus can be at least one stimulus selected from the group consisting of a temperature, a pH, an electric field, and light.  
         [0084]     Referring to  FIG. 3F , the resultant product illustrated in  FIG. 3F  is placed into a second aqueous solution  380  contained in a second container  370 . The second aqueous solution  380  contains neither the electron-emitting material  341  nor the conductive nano-particles  342 . When applying an external stimulus to the volume-changeable structure  330  or removing the applied external stimulus from the volume-changeable structure  330 , with the volume-changeable structure  330  being immersed in the second aqueous solution  380 , the volume-changeable structure  330  swells. Accordingly, the electron-emitting material  341  in the volume-changeable structure  330  is aligned substantially perpendicular to a surface of the electrode  310 . The electron-emitting material  341  is supported on the electrode  310  by the conductive nano-particles  342 . The external stimulus can be at least one stimulus selected from the group consisting of a temperature, a pH, an electric field, and light.  
         [0085]     Then, when the polymer  320  is removed from resultant product illustrated in  FIG.3F , the emitters  340  which are composed of the electron-emitting material  341  and the conductive nano-particles  342  are formed in the emitter aperture  315 , as illustrated in  FIG. 3G . Thus, the FED is completed. The polymer  320  can be removed by heating or a plasma treatment, for example.  
         [0086]      FIGS. 4A through 4F  are views of a method of manufacturing an FED according to another embodiment of the present invention.  
         [0087]     Referring to  FIG. 4A , a cathode electrode  410 , an insulating layer  412 , and a gate electrode  414  are sequentially formed on a substrate  400  and an emitter aperture  415  exposing a portion of the cathode electrode  410  is formed in the insulating layer  412 .  
         [0088]     Referring to  FIG. 4B , a photoresist  416  is formed on the entire surface of the resultant product illustrated in  FIG. 4A  to a predetermined thickness and patterned to expose a portion of the cathode electrode  410 . Then, a predetermined polymer  420 ′ comprising an electron-emitting material  441  and conductive nano-particles  442  is coated on the photoresist  416  and the exposed portion of the cathode electrode  410 . The electron-emitting material  441  can be composed of at least one material selected from the group consisting of CNTs, amorphous carbon, nano-diamonds, metal nano-wires, and metal oxide nano-wires. The conductive nano-particles  442  can be primarily composed of nano-metal particles. The polymer  420 ′ is a material which reversibly swells and shrinks in response to an external stimulus, such as an EAP or a hydrogel. Specifically, the polymer  420 ′ can be composed of at least one polymer selected from the group consisting of PDMS, PMA, PAA, PNIPAAm, PAM, HA, AL, PVA, PDADMAC, SA, AAm, NIPAAm, PVME, PEG, PPG, MC, PDEAEM, glucose, chitosan, and gelatin.  
         [0089]     Referring to  FIG. 4C , the polymer  420 ′ is patterned using a photolithographic process by a back-side exposure in which the photoresist  416  is used as a photomask, and then, the photoresist  416  is removed. Referring to  FIG. 4D , when water is removed from the polymer  420 ′, a volume-changeable structure  430  composed of the electron-emitting material  441 , the conductive nano-particles  442 , and a polymer  420  which reversibly swells and shrinks in response to an external stimulus is formed in the emitter aperture  415 .  
         [0090]     Referring to  FIG. 4E , the resultant product illustrated in  FIG. 4D  is placed into an aqueous solution  480  contained in a container  470 . The aqueous solution  480  contains neither the electron-emitting material  441  nor the conductive nano-particles  442 . When applying an external stimulus to the volume-changeable structure  430  or removing the applied external stimulus from the volume-changeable structure  430 , with the volume-changeable structure  430  being immersed in the aqueous solution  480 , the volume-changeable structure  430  swells. Accordingly, the electron-emitting material  441  in the volume-changeable structure  430  is aligned substantially perpendicular to a surface of the electrode  410 . The electron-emitting material  441  is supported on the electrode  410  by the conductive nano-particles  442 . The external stimulus can be at least one stimulus selected from the group consisting of a temperature, a pH, an electric field, and light.  
         [0091]     Then, when the polymer  420  is removed from the resultant product illustrated in FIG.  4 E, the emitters  440  which are composed of the electron-emitting material  441  and the conductive nano-particles  442  are formed in the emitter aperture  415 , as illustrated in  FIG. 4F . Thus, an FED is completed. The polymer  420  can be removed by heating or a plasma treatment, for example.  
         [0092]     As described above, by using the method of forming emitters and the method of manufacturing an FED according to the present invention, the emitters can be formed even at a low temperature and can be easily applied to a complicated structure.  
         [0093]     While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various modifications in form and detail can be made therein without departing from the spirit and scope of the present invention as defined by the following claims.