JP2011138795A - Method of manufacturing emitter, field emission cold cathode using this emitter, and plane image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an emitter capable of generating uniform and stable emission current with the use of a CNT film and obtaining superb emission characteristics, and to provide a field emission cold cathode using the emitter and a plane image display device. <P>SOLUTION: In the method of manufacturing the emitter, a CNT film 12 is formed which contains a plurality of carbon nanotubes (CNTs) to structure an emitter electrode on a glass substrate 10, a gate electrode 16 is formed through an insulating film 13 on the CNT film 12, a plurality of gate openings 17 are formed on the gate electrode 16 and the insulating film 13, and the CNTs in the gate openings 17 are upright-oriented. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a field emission cold cathode used in a flat display device (flat image display device) such as a field emission display (hereinafter also referred to as FED), and more particularly, a carbon nanotube as a film-like emitter. The present invention relates to a manufacturing method for easily manufacturing an emitter capable of exhibiting good emission characteristics when using (hereinafter also referred to as CNT).

  In recent years, carbon nanotubes, which are new carbon materials, are expected especially in applications as emitter materials such as field emission cold cathodes. The CNT has a hollow cylindrical shape obtained by rolling a granphen sheet in which carbon atoms are regularly arranged into a tube shape. The outer diameter is on the order of nanometers (nm), and the length is 0.5 to several tens of μm. It is a minute substance with an extremely high aspect ratio. In the CNT having such a shape, electric field concentration tends to occur at the tip portion, and a high emission current density can be expected. In addition, since CNT has high chemical and physical stability, it is expected to be stable against adsorption of residual gas in an operating vacuum, ion bombardment, and the like.

  There are two types of CNTs: single-wall nanotubes and multi-wall nanotubes. A single-walled nanotube is a tube of monoatomic layer thickness in which one graphene (carbon hexagonal network surface of a monoatomic layer) is closed in a cylindrical shape, and its diameter is about 2 nm. Multi-walled nanotubes are cylindrical graphene stacked in multiple layers, with an outer diameter of 5 to 50 nm and a central cavity diameter of 3 to 10 nm. Single-walled nanotubes that are frequently used as emitters can be generated by arc discharge using a carbon rod as an electrode. This production method is described in documents such as Nature Vol. 354 (1991) p. 56-58 (Non-patent Document 1), and in that, in an atmosphere of 66,500 Pa (500 Torr) helium or argon gas. There is a description that arc discharge is performed using a carbon rod electrode to which iron, cobalt or nickel is added as a catalyst metal.

  In addition, transfer methods for forming CNTs into a film are disclosed in, for example, Science Vol. 268 (1995), page 845 (Non-patent Document 2) and Science Vol. 270 (1995), page 1179 (Non-patent Document 3). It is described in. In this transfer method, a CNT suspension in which CNTs are dispersed in a solution is filtered through a ceramic filter having a pore size of 0.2 μm, and the back surface of the CNT film remaining on the filter is pressed onto a substrate. Remove only the filter. Thereby, a thin film containing CNTs is formed on the substrate.

  When the CNT film formed as described above is applied to a display, the CNT film is used as a cathode (emitter) as an electron source. In the bipolar tube structure in which the anode electrode and the phosphor are disposed in the vicinity thereof, as described in Appl. Phys. Letters, Volume 72, p. 2912, 1998 (non-patent document 4), the anodes facing each other. A voltage of, for example, 300 V is applied between the electrode and the emitter, and electrons emitted from the emitter are applied to the phosphor on the anode electrode side to excite and emit light, thereby displaying characters and the like on the display.

  An example of a triode structure is shown in FIG. In the triode structure, the emitter 12b using CNT is used for the field emission cold cathode, and the gate electrode 25 is disposed between the emitter 12b and the anode electrode 24. A conductive substrate or conductive layer 11 is formed on the glass substrate 10, a CNT film 12 is deposited on the conductive layer 11, and a gate electrode 25 is formed on the CNT film 12 via an insulating film 23.

  Further, a part of the CNT film 12 is exposed by the gate opening 17 penetrating the gate electrode 25 and the insulating film 23 to form the emitter 12b. An anode electrode 24 is disposed above the glass substrate 10 including the CNT film 12 and the gate electrode 25 with a predetermined distance, and the space between the two is maintained in a vacuum. In such a triode structure, a negative potential is applied to the CNT film 12 and a positive potential is applied to the anode electrode 24 and the gate electrode 25, respectively, so that the emitter 12b exposed in the gate opening 17 is directed toward the anode electrode 24. Electrons can be emitted.

Nature Vol.354 (1991) p.56-58 Science Vol.268 (1995) p.845 Science Vol.270 (1995) p.1179 Appl.Phys.Letters, Volume72, p.2912, 1998

  By the way, when a flat image display device such as an FED is manufactured using the above triode structure, an insulating film is formed on the CNT film, and then an opening is formed in the insulating film using an etching solution or an etching gas. The CNTs standing upright near the surface of the CNT film may be lost due to the influence of the etching solution or the etching gas, and good electric field concentration characteristics may be impaired.

  FIG. 12 shows a CNT film manufactured by a conventional manufacturing method. In this manufacturing method, a mixed solution in which CNTs 12a are dispersed in a binder solution is applied onto the conductive layer 11 on the surface of the substrate 10, and the CNT film 12 is formed while increasing the adhesion between the substrate 10 and the CNTs 12a. In this method, most of the CNTs 12a on the surface of the CNT film are tilted toward the substrate surface due to the viscosity and surface tension of the binder solution, or are buried in the binder, so that the upright state is impaired and uniform under a low voltage. Realizing emission characteristics is extremely difficult.

  In many cases, the binder is mainly composed of an insulator such as a resist, water glass, and an acrylic resin. When the surface of the CNT film 12 is covered with this insulator, the surface barrier of electrons during electron emission is reduced. Substantial increase in emission efficiency. For this reason, although the adhesive force between the substrate 10 and the CNT film 12 is improved, an emitter in which the CNTs 12a are not oriented upright cannot fully exhibit the advantage of having the CNT film.

  In view of the above, an object of the present invention is to provide a method for manufacturing an emitter capable of generating a uniform and stable emission current while using a CNT film and obtaining good emission characteristics. It is another object of the present invention to provide a field emission cold cathode using the emitter obtained by the above manufacturing method, and a flat image display device using the field emission cold cathode.

In order to achieve the above object, a method for manufacturing an emitter according to the first aspect of the present invention includes:
Forming a CNT film constituting an emitter including a plurality of carbon nanotubes (CNT) on a substrate;
Forming an electrode on the CNT film via an insulating film;
Forming a plurality of openings in the electrode and the insulating film;
And erecting the CNTs on the surface of the CNT film in the opening,
It is characterized by that.

  The phrase “upright” in the present invention means that the tip portion of the CNT in the CNT film has an angle of 50 degrees or less with respect to the normal line on the substrate. Although the upright alignment is promoted by the electrostatic force by applying an electric field, the upright alignment referred to in the present invention is a “state after promotion”. In addition, the phrase “side-down arrangement” in the present invention means an arrangement state in which the CNTs fall along the substrate due to the surface tension of the liquid.

  In the emitter manufacturing method according to the first aspect of the present invention, since the CNTs are oriented upright, the advantages of having the CNT film are fully exerted, and a uniform and stable emission current is generated to obtain good emission characteristics. It becomes possible. In the upright alignment step of the CNTs, it is preferable that the CNTs are aligned upright by attaching an adhesive sheet on the CNT film and then peeling off the adhesive sheet. Thereby, the upright orientation of CNT can be obtained by a very simple process using an adhesive sheet.

  A preferred method for manufacturing an emitter of the present invention includes a step of forming an electrode on the CNT film through an insulating film prior to the CNT upright alignment step, and a step of forming a plurality of openings in the electrode and the insulating film. In the upright alignment step of the CNTs, the CNTs in the opening are aligned upright.

  In this case, since the CNTs are oriented upright in the opening, the advantages of having the CNT film can be fully exhibited, and a uniform and stable emission current can be generated to obtain good emission characteristics.

  Moreover, it is preferable that the said upright alignment process includes the process of making an adhesive sheet approach in the said opening, and then peeling off this adhesive part. Thereby, even when the hole diameter of the opening of the electrode is small, the pressure-sensitive adhesive sheet applied on the electrode is pressed, the pressure-sensitive adhesive portion enters the opening, and the pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive portion is in contact with the CNT film surface is peeled off. Thus, the CNTs can be easily oriented upright.

  Further, prior to the step of forming the insulating film and the electrode, the CNT film has a step of vertically aligning the CNTs on the surface of the CNT film, and forming a cover film containing fine particles on the CNT film. It is also a preferable aspect to include a step of allowing the pressure-sensitive adhesive sheet to enter the opening and then peeling off the pressure-sensitive adhesive sheet to remove at least a part of the cover film. Thereby, even when the hole diameter of the opening of the electrode is small, just press the pressure-sensitive adhesive sheet applied on the electrode and enter the adhesive part into the opening, and after peeling the adhesive part after contacting the cover film surface, A part of the exposed portion of the cover film can be removed to obtain CNTs in an upright orientation state.

  Furthermore, it is preferable that the step of vertically aligning with the pressure-sensitive adhesive sheet is performed under reduced pressure. In this case, since the pressure-sensitive adhesive sheet can be easily and easily entered into the opening, the upright alignment treatment of the CNTs on the surface of the CNT film in the opening becomes easier. Further, even when the pressure-sensitive adhesive sheet has air permeability, the pressure-sensitive adhesive sheet can be easily entered into the opening.

  It is preferable that adhesive protrusions that enter the plurality of openings are formed on the surface of the adhesive sheet. In this case, by pressing the adhesive sheet on the electrode with a roller or the like, the adhesive convex portion can easily enter the corresponding opening, and the CNT film surface on the peripheral surface side in the opening is subjected to the upright alignment treatment. Can do. Furthermore, if the adhesive convex portions are arranged smaller than the plurality of openings, the adhesive convex portions can be more reliably entered into the openings.

  The adhesive strength of the adhesive sheet is preferably smaller than the adhesive strength of the emitter to the substrate. In that case, when the pressed adhesive convex portion is peeled off, the emitter is not damaged. Specifically, the adhesive strength of the adhesive sheet can be set to exceed 0.002 N / mm and less than 0.2 N / mm.

  According to a second aspect of the present invention, there is provided a method of manufacturing an emitter, wherein a CNT film constituting an emitter including a plurality of carbon nanotubes (CNT) is formed on a substrate, the CNTs of the CNT film are aligned upright, and the upright alignment is performed. A metal protective film is formed on the CNT film, and the entire substrate including the metal protective film is immersed in an etching solution to remove the metal protective film.

  In the emitter manufacturing method according to the second aspect of the present invention, since the CNTs are held in an upright orientation state by the metal protective film, the subsequent film formation process of the insulating film and electrode becomes simple, and the metal is etched in the etching solution. By removing the protective film, CNTs in an upright orientation can be revealed and formed as an emitter.

  According to a preferred method of manufacturing an emitter of the present invention, prior to the metal protective film removing step, an electrode is formed on the metal protective film through an insulating film, and a plurality of openings are formed in the electrode and the insulating film. And the step of removing the metal protective film includes removing the metal protective film in the opening by etching. In this case, even in the configuration in which the emitters are formed in the plurality of openings, the metal protective film is used to hold the CNTs in an upright orientation state, thereby facilitating the subsequent film formation process of the insulating film and the electrode, thereby protecting the metal. A CNT in an upright orientation state can be obtained by simply removing the film by etching.

  Alternatively, instead of the above, following the step of removing the metal protective film, the step of replacing the etching solution with water while maintaining the CNT film exposed in the opening below the liquid level, and the water It is also a preferable aspect to include a step of freezing and then sublimating and drying CNT in an upright orientation state in the CNT film.

  In this case, even when the opening diameter of the electrode is so small that the adhesive sheet cannot be used, the metal protective film is removed by etching after the opening is formed, and the CNT film is dried by sublimating water without going through the liquid phase, The standing CNTs can be exposed in the openings in an upright state without being laid down by the surface tension of water and arranged. Moreover, since the etching solution is replaced with water while the CNT film exposed from the opening is held below the liquid surface, the exposed CNT can be transferred to the next step without being brought into contact with air.

  Alternatively, instead of the above, following the step of removing the metal protective film, replacing the etching solution with a supercritical fluid while maintaining the CNT film exposed in the opening below the liquid level; and It is also a preferable aspect to include a step of removing the supercritical fluid by transferring it to a supercritical state and drying the CNT film.

In this case, even when the hole diameter of the opening of the electrode is extremely small, the metal protective film is removed by etching after the opening is formed, the supercritical fluid is transferred to the supercritical state and removed, and the CNT film is dried. The exposed CNTs can be exposed in the opening in an upright state without being laid down by the surface tension and arranged. As the supercritical fluid, at least one of CO ₂ , N ₂ , N ₂ O, xenon and SF _{6 in} a liquid state can be used.

  Alternatively, after the metal protective film removal step, the etching solution is replaced with a solution having a lower surface tension than the etching solution while maintaining the CNT film exposed in the opening below the liquid level. It is also a preferred embodiment to dry the CNT film.

  Thereby, even when the hole diameter of the opening of the electrode is extremely small, the metal protective film is removed by etching after the opening is formed, and then the solution having a surface tension smaller than that of the etching solution is removed and the CNT film is dried. The CNTs can be exposed in the opening without being laid down by the surface tension and arranged.

  It is preferable that the drying step is performed under a constant pressure and / or a constant temperature. In this case, the CNT film can be dried without changing the good upright alignment state of the CNT.

  The emitter manufacturing method according to the third aspect of the present invention is a manufacturing method in which an electrode is manufactured using a CNT film including a plurality of carbon nanotubes (CNTs). The CNT film is wetted with a predetermined solution, and the CNTs are arranged side by side. And forming a predetermined film on the CNT film.

  When aligning CNTs of several μm or less upright on the surface of the CNT film and forming the film on the CNT film in the subsequent process, for example, even if a solvent containing a binder is applied, the solvent does not become familiar with the CNT film, and the entire surface is excellent. Application may not be possible. Alternatively, even if it can be applied to the entire surface, fine bubbles may melt, and bubbles or surface irregularities may be generated in the binder layer fired after removal of the binder solvent. However, according to the method for manufacturing an emitter of the present invention, since the CNTs of the CNT film are arranged side by side during at least the subsequent predetermined film forming step, a good film forming process on the CNT film is realized.

  In addition, by applying the emitter manufactured by the emitter manufacturing method to a field emission cold cathode, a structure with good emission characteristics can be obtained. Furthermore, by applying such a field emission type cold cathode to a flat image display device, a flat image display device with good emission characteristics can be obtained.

In the flat image display device of the present invention, in the flat image display device in which the area of one pixel is S (cm ² ), the number density of vertically aligned CNTs is 1 / S (pieces / cm ² ) or more. Features.

  According to the flat image display device of the present invention, a uniform and high-definition display device structure using upright oriented CNTs can be obtained.

  As described above, according to the present invention, an emitter that generates uniform and stable emission current while using a CNT film and exhibits good emission characteristics, a field emission cold cathode using the emitter, and the field emission type A flat image display device using a cold cathode can be obtained.

It is a perspective view which shows flat image display apparatuses, such as FED, which applied the emitter manufactured with the manufacturing method which concerns on the example of 1st Embodiment of this invention. The process of manufacturing the field emission type cold cathode used for the flat image display apparatus which concerns on 1st Embodiment is shown, (a)-(e) is sectional drawing which shows each process in steps. The process of manufacturing the field emission type cold cathode used for the flat image display apparatus which concerns on 1st Embodiment is shown, (a) And (b) is sectional drawing which shows each process in steps. The upright orientation method in the first embodiment is shown, and (a) to (c) are cross-sectional views showing each step step by step. The manufacturing method which concerns on the 2nd Embodiment of this invention is shown, (a)-(d) is sectional drawing which shows each process in steps. The manufacturing method of 3rd Embodiment of this invention is shown, (a)-(e) is sectional drawing which shows each process in steps. The manufacturing method of the 3rd Embodiment of this invention is shown, (a)-(c) is sectional drawing which shows each process in steps. It is a correlation diagram of the pressure and temperature in the solid phase, liquid phase, and gas phase of pure water. It is sectional drawing which shows the manufacturing method which concerns on the example of 4th Embodiment of this invention, (a)-(c) shows each process in steps. It is a graph which shows the adhesive force dependence of the adhesive sheet in an emission site number density. It is a figure which shows typically an example of the conventional triode structure. It is sectional drawing which shows the CNT film | membrane manufactured with the conventional manufacturing method.

  Hereinafter, the present invention will be described in more detail based on an embodiment of the present invention with reference to the drawings. FIG. 1 is a perspective view showing a flat image display device such as an FED to which an emitter manufactured by the emitter manufacturing method according to the first embodiment of the present invention is applied.

  The flat image display device has a plurality of strip-like conductive layers 11 extending on the glass substrate 10 in parallel in the left-right direction of FIG. A CNT film 12 having the same width is deposited on each conductive layer 11 to form a cathode (emitter) line 15. In addition, SOG (Spin On Glass), polyimide, acrylic resin, or the like is dropped and applied (spin coated) so as to cover the entire surface of the glass substrate 10 including the CNT film 12 to form the insulating film 13.

  On the insulating film 13, a strip-like gate electrode 16 extends in a direction orthogonal to the cathode line 15 and in parallel with each other to form a gate line. A gate opening 17 having a predetermined diameter constituting an electron emission portion is formed at the intersection of the cathode line 15 and the gate line, and the CNT film 12 exposed to the gate opening 17 constitutes an emitter.

  Above the glass substrate 10 on which the electron emission portion is formed, an anode panel (see FIG. 10) coated with phosphors of RGB (red, green, blue) is spaced from the glass substrate 10 at a predetermined interval. Opposed to each other. Thus, a flat image display device that performs a display operation by selectively applying a voltage to the cathode line 15 and the gate line is configured. Further, the space between the glass substrate 10 and the anode panel is kept in a vacuum.

  2 and 3 show a process for manufacturing a field emission cold cathode used in the flat image display device according to the present embodiment by using a CNT film, and FIGS. 2A to 2E and FIG. (A) And (b) is sectional drawing which shows each process in steps.

  First, as shown in FIG. 2A, a conductive layer 11 is formed on a glass substrate 10 by a chemical vapor deposition (CVD) method or the like, and as shown in FIG. Then, the CNT film 12 is formed by a transfer method or the like. The CNT of the CNT film 12 can be produced by an arc discharge method, a laser ablation method, or the like, but in this embodiment, it is produced by using an arc discharge method.

  Next, as shown in FIG. 2C, an insulating film 13 is formed on the CNT film 12, and a metal film such as aluminum is deposited on the insulating film 13 as shown in FIG. It is formed on the electrode 16. Further, as shown in FIG. 2E, a gate opening 17 that penetrates the gate electrode 16 and the insulating film 13 and exposes a part of the CNT film 12 is formed by etching or the like. The emitter 12b is constituted by the CNT film 12 exposed from the gate opening 17. Note that a conductive substrate can be used instead of the glass substrate 10. In this case, the conductive layer 11 is not necessary.

  Here, the process which manufactures CNT contained in the CNT film | membrane 12 by an arc discharge method is demonstrated. First, a reaction vessel (not shown) is filled with 66,500 Pa (500 Torr) of He gas, and the tips of two carbon rods (not shown) containing a catalytic metal are opposed to each other. Generate arc discharge. Thereby, the solid containing CNT is deposited on the surface of the carbon rod on the cathode side and the inner wall of the reaction vessel, respectively. Arc discharge is performed, for example, by applying a voltage of 18 V between both carbon rods and flowing a current of 100 A.

  The deposited solid contains graphite, amorphous carbon, or catalytic metal having a particle diameter of about 10 to 100 nm in addition to CNT. The CNTs obtained here are single-walled nanotubes having a diameter of 1 to 5 nm, a length of 0.5 to 100 μm, and an average length of about 2 μm. In addition to arc discharge, CNTs produced using a laser ablation method also basically have the same size as CNTs produced by the arc discharge method.

  Next, the crude product containing the CNTs is suspended in ethanol and dispersed using ultrasonic waves. Further, the suspension is filtered using a membrane filter having a pore size of 0.5 μm. At this time, impurity fine particles other than CNT pass through the filter because they are smaller than the pore size of the filter, but CNT having a length of 0.5 μm or more remains on the filter. Only the CNT remaining on the filter is recovered and purified.

  Subsequently, as shown in FIG. 3A, a binder layer 14 having a thickness of 0.8 μm is formed on the conductive layer 11 formed on the glass substrate 10, and immediately thereafter, the binder layer 14 is formed on the binder layer 14 in advance. The CNT film 12 having a thickness of 5 μm is transferred by a transfer method. As the binder layer 14, a resin such as a resist, SOG (Spin on Glass), or acrylic can be used.

  Next, the glass substrate 10 on which the CNT film 12 is formed is accommodated in a predetermined apparatus, and subjected to a baking treatment to cure the binder layer 14 to form a completed CNT film 12 as shown in FIG. . Here, the CNT film 12 is formed by a transfer method. However, the present invention is not limited to this, and the CNT film 12 can also be formed by a method such as screen printing or spraying.

  In this case, the CNT film 12 was formed using a suspension obtained by ultrasonically dispersing CNTs 12a in a solution such as ethanol or binder having low viscosity and high volatility. The higher the CNT concentration in the suspension, the more easily the effect of the present invention can be obtained. Here, 2 grams or more of CNT was used for 1 liter of ethanol.

  In the state immediately after formation of the CNT film 12 shown in FIG. 3A, the CNTs 12a are oriented almost upright from the surface of the CNT film 12 with respect to the glass substrate 10. These processes are easy to process and suitable for increasing the area, but when passing through a process such as water washing, the upright CNTs 12a are detached from the glass substrate 10 and disappear as shown in FIG. 3 (b). Alternatively, a side-by-side arrangement along the glass substrate 10 occurs due to the viscosity and surface tension of the binder layer 14.

  Next, a process for vertically orienting the CNTs of the side-by-side aligned CNT film will be described. FIG. 4 shows an upright orientation method in this embodiment, and (a) to (c) are cross-sectional views showing each step step by step. FIG. 4 (a) is an enlarged view of FIG. 2 (e).

  As shown in FIG. 4B, a pressure-sensitive adhesive sheet 21 having a pressure-sensitive adhesive 20 attached to the thin film 19 is pressed from above the gate electrode 16, and a part of the pressure-sensitive adhesive 20 enters the gate opening 17 to cause the CNT film 12. Touch the surface. As the jig for pressing, a roller or a press machine whose surface is made of a flexible member such as cloth, sponge, rubber, or gel material can be used.

  Next, as shown in FIG. 4C, when the pressure-sensitive adhesive sheet 21 is peeled off, the CNTs 12a on the surface of the CNT film 12 are pulled in a state where they are attached to the pressure-sensitive adhesive material 20, and are in an upright orientation state. This upright orientation means that the tip of the CNT 12a in the CNT film 12 has an angle of 50 degrees or less with respect to the normal line in the glass substrate 10. When the adhesive sheet 21 is peeled off, in addition to a part of the CNT 12a on the surface of the CNT film 12, nanoparticles (particulate impurities) deposited with the CNT by the arc discharge method, amorphous carbon, metal catalyst powder, or CNT Even if a part of the binder layer 14 necessary for fixing is removed, there is no problem in obtaining the effect of the present invention.

  Here, Table 1 shows the results of the characteristics of the treatment material, the orientation of the CNTs, and the residual state of the residue when the experiment was performed by changing the type and adhesive strength of the adhesive material used and the thickness of the adhesive sheet. Here, only a CNT film is used, and there is no structure having an insulating film and a gate electrode on the CNT film.

  Table 1 lists samples A to G of the pressure-sensitive adhesive sheet, and each sample has the same thickness of 0.2 mm, but sample A has a pressure-sensitive adhesive strength of 2.0 N / mm, and sample B has a thickness of 0.4 N. / Mm adhesive strength, sample C has an adhesive strength of 0.003 N / mm, sample D has an adhesive strength of 0.002 N / mm, and samples EG have the same adhesive strength of 0.5 N / mm. Have Sample E has the same adhesive structure as Samples A to D, but Sample F has a structure in which adhesive fine particles are attached to the thin film 19 with a weak adhesive material, and Sample G is adhesive due to its own adhesive force. It has a structure in which fine particles are attached to the thin film 19.

  From Table 1, it can be seen that in the sample D having the smallest adhesive strength of 0.002 N / mm, the orientation of the CNTs is not sufficient and the adhesive strength is insufficient. Further, in the sample A having a maximum adhesive strength of 2.0 N / mm, the CNT film 12 was peeled off. From these results, it is understood that a value exceeding 0.002 N / mm and less than 2 N / mm is preferable as the adhesive strength. According to the pressure-sensitive adhesive sheet having an adhesive force in this range, the emitter 12b having a good upright orientation without peeling off the CNT film 12 can be obtained. Further, in the samples F and G, part of the adhesive fine particles was detached when pressed against the CNT film 12 and remained as a residue on the surface of the CNT film 12. From this result, it can be seen that it is desirable to use an adhesive sheet having a structure in which the adhesive material 20 is integrally attached to the thin film 19 as in the samples A to C. In general, it can be seen that the alignment result does not depend on the film thickness of the sample.

  Next, Table 2 shows the characteristics of the treatment material, the orientation of the CNT, the remaining state of the residue, and the result of gate peeling when the experiment was performed by changing the adhesive strength of the used adhesive material and the thickness of the adhesive sheet. Here, the upright orientation on the surface of the CNT film having a gate structure was investigated.

  Table 2 lists samples H to N of the adhesive sheet. Sample H has an adhesive strength of 0.2 N / mm, Sample I has an adhesive strength of 0.18 N / mm, and Sample J has an 0.003 N / mm adhesive strength. The adhesive strength and sample K each have an adhesive strength of 0.002 N / mm, and samples L to N have the same adhesive strength of 0.5 N / mm. Samples H to K have the same thickness of 2 mm, but sample L is 2 mm, sample M is 1.8 mm, and sample N is 0.02 mm.

  From Table 2, gate peeling occurs when the adhesive strength is 0.2 N / mm or more as in Sample H, and CNT orientation is not sufficient when the adhesive strength is 0.002 N / mm or less as in Sample K. I understand that. Therefore, it can be seen that the adhesive strength is more preferably set to exceed 0.002 N / mm and less than 0.2 N / mm. If an adhesive sheet having an adhesive force in this range is used, an emitter 12b having a better upright orientation with no CNT film 12 peeling or residue is obtained.

  Although not described in Table 2, a 2 mm thick adhesive having a structure in which an adhesive material 20 mainly composed of natural rubber and added with a resin or an antioxidant is attached to a film thin film 19 made of a thin cellophane. When the sheet 21 was used with an inner diameter of the gate opening 17 of 100 μm and an insulating film thickness of 20 μm, the adhesive sheet 21 could not enter the gate opening 17 and an upright alignment result could not be obtained. From this, it was found that the thickness of the pressure-sensitive adhesive sheet 21 is desirably less than 2 mm.

  When the total film thickness of the insulating film 13 and the gate electrode 16 is 5 μm and the hole diameter of the gate opening 17 is 5 to 20 μm, the film thickness of the adhesive sheet 21 is preferably less than 0.5 mm. In the range where the hole diameter is d to 4d with respect to the film thickness d of the electrode 16, the film thickness of the adhesive sheet 21 is preferably less than 100d. Since the flexibility of the pressure-sensitive adhesive sheet 21 is proportional to the Young's modulus and thickness, good results can be obtained by appropriately selecting the Young's modulus and thickness of the material.

  By the way, when performing the upright orientation of the emitter 12b using the adhesive sheet 21 in the atmosphere, the gas is enclosed in the gate opening 17, so that even if the adhesive sheet 21 is pressed, the adhesive material is repelled by the repulsion of the enclosed gas. There is a problem that 20 cannot sufficiently contact the CNT surface. However, in the case where the adhesive material 20 is made by foaming, for example, the surface of the adhesive material 20 is uneven, and as a result, has air permeability. When the thin film 19 is pressed, the gas in the gate opening 17 is Is discharged out of the gate opening 17 from the concave portion. In this case, if the convex portion (adhesive convex portion) is smaller than the gate opening 17, the convex portion of the adhesive material 20 can easily enter the corresponding gate opening 17 and reach the surface of the CNT film 12 very effectively. be able to.

  Further, the glass substrate 10 in a state where the adhesive sheet 21 is disposed on the gate electrode 16 is accommodated in the decompression device, and the adhesive sheet 21 is pressed under a reduced pressure atmosphere of, for example, 66,500 Pa (500 Torr) or less. At this time, since the amount of gas in the fine gate opening 17 is reduced, even if the sealed gas repels when the pressure-sensitive adhesive sheet 21 is pressed, the pressure-sensitive adhesive material 20 can contact the CNT surface. In particular, when the pressure is reduced to 13,300 Pa (100 Torr) or less, the volume of the enclosed gas becomes 1 / 7.6 or less, and the influence of the enclosed gas is almost eliminated. For this reason, the adhesive material can be brought into contact with a portion close to the peripheral edge in the gate opening 17 in the emitter 12b, and a proper upright orientation capable of obtaining good emission characteristics can be obtained.

  In the present embodiment, the thin film 19 is used as a member that supports the adhesive material 20, but a jig such as a metal may be used instead. In that case, the jig does not need to have a flat shape. For example, the CNT 12a in the gate opening 17 is selectively upright by pressing or separating the adhesive material only on the portion of the CNT film 12 that should be oriented upright. You can also In this case, it is not necessary for the adhesive material to adhere to the entire surface of the jig, and it is sufficient if it is partially attached. For example, in the case where the adhesive material 20 has an uneven shape, it is sufficient that the adhesive is attached only to the convex portion.

  As described above, by giving the in-plane selectivity of the adhesive material on the thin film 19, the CNTs 12a at arbitrary positions can be oriented upright or patterned. Further, the pressing step and the removing step by the pressure-sensitive adhesive sheet 21 are not limited to once, and can be repeated as many times as necessary. Further, as described on pages 320 and 324 of Tech. Digest of SID2000, a triode structure can be formed by installing a CNT film grid manufactured by the above method. When the CNTs 12a are oriented upright before the gate opening 17 is formed or without the gate opening 17, the adhesive sheet 21 is simply attached on the CNT film 12, and then the adhesive sheet 21 is peeled off. As a result, the CNTs 12a can be oriented upright. Thereby, the upright orientation of the CNTs 12a can be obtained by an extremely simple process using the adhesive sheet 21.

  Next, a method for manufacturing an emitter according to the second embodiment of the present invention will be described. FIG. 5 shows a manufacturing method according to this embodiment, and (a) to (d) are cross-sectional views showing each step step by step.

  First, as shown in FIG. 5A, a CNT film 12 containing a plurality of CNTs 12a is formed on a glass substrate 10, and a metal such as silver is formed on the CNT film 12 as shown in FIG. 5B. Fine particles 22 are applied. As a result, each CNT 12a is buried in an upright orientation in a large number of fine metal particles 22, so that the protruding CNTs 12a are eliminated on the surface of the CNT film 12 and flattened.

  Next, an acrylic resin, an epoxy resin, a polyimide resin, SOG, or the like is formed on the cover film (22) formed by applying the metal fine particles 22 to a thickness of 20 μm by the spin coater to form the insulating film 13. Further, a metal film (16) is formed on the insulating film 13, and a plurality of gate openings 17 are formed in both the metal film (16) and the insulating film 13, and the metal film (16) is formed on the gate electrode 16. A part of the cover film (22) is exposed from the gate opening 17 while being formed.

  Subsequently, the adhesive portion of the adhesive sheet 21 (FIG. 4B) enters the gate opening 17 to contact the surface of the cover film (22), and then peeled off. At least a part of the exposed portion of the cover film (22) is removed. The CNT film 12 is exposed by removing. Thereby, the CNTs 12a on the surface of the CNT film 12 appear in an upright orientation state.

  In this embodiment, even when the hole diameter of the gate opening 17 of the gate electrode 16 is small, the adhesive sheet 21 applied on the gate electrode 16 is pressed to cause the adhesive portion to enter the gate opening 17, and the adhesive portion is covered with the cover film ( 22) By simply peeling off the pressure-sensitive adhesive sheet 21 brought into contact with the surface, a part of the exposed portion of the cover film (22) can be removed to expose the CNTs 12a in the upright orientation state. Thereby, it is possible to obtain good emission characteristics that generate a uniform and stable emission current.

  In the present embodiment, the metal fine particles 22 are used for forming the cover film. However, the present invention is not limited to metals, and organic substances such as silicon dioxide and resin can also be used. In this case, an inorganic material is preferable in consideration of gas release. Moreover, the pressing / removal process by the adhesive sheet is not limited to once, and can be repeated as necessary.

  Next, an emitter manufacturing method according to the third embodiment of the present invention will be described. 6 and 7 show a manufacturing method according to the present embodiment, and FIGS. 6A to 6E and 7A to 7C are cross-sectional views showing each step step by step.

  First, as shown in FIG. 6A, a conductive layer 11 and a CNT film 12 are formed in this order on a glass substrate 10 as in the first embodiment. The formation method of the CNT film 12 may be any one of transfer, coating, spraying, and screen printing, but here, spraying that enables uniform deposition over a large area is performed. Spraying was performed after ultrasonically dispersing CNTs in the acrylic resin solution. Also in this embodiment example, single-walled CNTs produced by an arc discharge method were used.

  Next, as shown in FIG. 6B, after spraying, the CNT film 12 is baked, and further, an adhesive sheet is applied so as to have a uniform pressure over the entire surface of the CNT film 12, and then peeled off. Thus, the CNTs 12a on the surface of the CNT film 12 are oriented upright. The pressure-sensitive adhesive sheet used here follows the specifications described above with reference to Tables 1 and 2. However, since the upright orientation is performed before the formation of the triode structure here, the adhesive force of the adhesive sheet is not limited by peeling of the gate electrode or the insulating film. Therefore, an adhesive sheet having sufficient adhesive strength can be used as long as the CNT film itself is not peeled off.

  Subsequently, as shown in FIG. 6C, an aluminum layer 18 is deposited to a thickness of 0.6 μm on the surface of the CNT film 12 by using a vapor phase growth method such as sputtering or CVD. The aluminum layer 18 maintains the upright orientation of the CNTs 12 a on the surface of the CNT film 12 and functions as a protective film on the surface of the CNT film 12. Further, the vapor phase growth method was used because the coating characteristics were good and the upright-oriented CNTs 12a could be held as they were. For example, when a similar deposited film is formed on the surface of the CNT film 12 by coating or the like, the surface CNTs are again laid down due to the influence of the surface tension of the coating solution, and the effects of this embodiment described later are sufficiently obtained. It will not be possible.

  Here, aluminum is used as the protective film. However, the deposition material is a material that has high adhesion to CNT and an insulating film deposited on the upper layer of the CNT, and can be deposited within the heat resistant temperature range of the glass substrate 10, for example, In addition, a single metal such as titanium, gold, and tungsten, a metal compound such as titanium nitride and aluminum oxide, or an insulating material can be used. Note that, as the thickness of the aluminum layer 18 increases, the effect of planarization on the surface CNT 12a is improved. Therefore, when the thickness is increased, the generation of bubbles during the formation of an insulating film, which will be described later, can be suppressed. However, since the growth rate is slow according to the vapor phase growth method, the deposited film thickness is set to 0.6 μm here.

  Next, as shown in FIG. 6D, an insulating film 23 is formed on the aluminum layer 18 covered with the CNT film 12 by applying polyimide to a thickness of 10 μm. Further, a gate electrode is formed on the insulating film 23. 25 is formed to a thickness of 0.2 μm. Even during these steps, the CNTs 12a are maintained in the upright orientation state by the aluminum layer 18, and therefore do not have a side-by-side arrangement.

  Subsequently, as shown in FIG. 6E, the gate electrode 25 and the insulating film 23 are sequentially removed by dry or wet etching using a photolithography technique to form a gate opening 17 of 100 μm. Also at this time, the CNT 12a is protected by the aluminum layer 18, and there is no problem such as deterioration due to the influence of the etching process. Here, the gate electrode 25 is formed prior to the gate opening 17, but conversely, the gate opening 17 can be formed in the insulating film 23 prior to the formation of the gate electrode 25.

  Next, as shown in FIG. 7A, the glass substrate 10 having the gate opening 17 and the like is immersed in an etching solution 27 such as phosphoric acid or hydrochloric acid filled in the container 28, and the gate opening is allowed to elapse for a predetermined time. The aluminum layer 18 exposed from 17 is removed by etching. Further, as shown in FIG. 7B, the inside of the container 28 is replaced with pure water 29 while monitoring at least the surface of the etching solution 27 to be lower than the surface of the CNT film 12, and then the entire container 28 is rapidly frozen. .

After the pure water 29 is frozen, the entire container 28 is transferred into a vacuum chamber (not shown), kept at a temperature of 10 ° C., and evacuated for 4 hours or more under a pressure (vacuum) of 1 × 10 ⁻¹ Pa or less. . As a result, the pure water 29 frozen in the solution 28 is sublimated without going through the liquid phase, so that the pure water 29 is dried and removed while maintaining the upright orientation state of the CNTs 12a without affecting the surface tension. be able to.

  FIG. 8 is a correlation diagram of pressure and temperature in the solid phase, liquid phase, and gas phase of pure water. The arrows in the figure indicate the cleaning and drying procedures in this embodiment. Point A shows a state where the aluminum layer 18 on the CNT surface is replaced with pure water 29 after etching, and in this case, the upper part of the CNT film 12 is covered with pure water (liquid phase). Next, by freezing the pure water 29, the vertically oriented CNTs 12a are frozen as they are, and become a solid phase (point B).

  Further, the entire container 28 is depressurized in the vacuum chamber, so that the boundary between the solid phase and the gas phase is reached (point C). Subsequently, by reducing the pressure, the pure water 29 undergoes a phase change directly from the solid phase to the gas phase and does not pass through the liquid phase (point D). Thereby, the CNT 12a on the surface of the CNT film 12 is dried while maintaining the upright alignment state without being affected by the surface tension of the pure water 29. Further, by changing the pressure from point C and increasing the temperature, the phase change from the solid phase to the gas phase can be rapidly performed (point E).

Specifically, the degree of vacuum in the chamber is maintained at 1 × 10 ⁻¹ Pa, and the temperature of the glass substrate 10 is maintained at 60 ° C. The drying time at this time depends on the size of the element including the glass substrate 10 and the amount of pure water at the time of freezing. For example, when the area of the element is 7 × 7 cm ² and the amount of pure water 29 is 20 ml. Is preferably about 2 hours.

  Further, it is desirable that the two drying paths (point D and point E) from the point C shown in FIG. 8 are implemented using an apparatus having a feedback function for keeping the temperature or pressure constant. When the feedback function is not used, for example, when the phase is changed from the point C to the point D, the substrate temperature is lowered due to the heat of vaporization, and there is a possibility that the vaporization rate is lowered. Further, when the phase is changed from the point C to the point E, if there is an influence such as sudden vacuum deterioration, there is a possibility of vaporization via the liquid phase. At this time, if the feedback function is not used, problems such as local deterioration of the upright orientation of the CNTs 12a or inability to obtain reproducibility arise.

  In the present embodiment, pure water 29 is used as a replacement liquid for the etching solution 27. However, an aqueous solution containing impurities may be used as long as it has a property capable of phase transition from the solid phase to the gas phase without passing through the liquid phase. Can be used.

  Further, when the surface tension is replaced with an extremely small liquid such as ethanol or fluorinate without using the above-described freezing / drying method, the CNT 12a may be laid down in a subsequent drying process. It is possible to dry the CNTs 12a while maintaining the upright alignment state.

Next, an emitter manufacturing method according to the fourth embodiment of the present invention will be described with reference to FIG. The manufacturing method of this embodiment example is the same as the process up to FIG. 7A in the third embodiment example, but the cleaning and drying methods after FIG. 7B are different. That is, in this embodiment, the etching solution 27 is replaced with liquid CO ₂ instead of the pure water 29.

Subsequently, the container 28 filled with liquid CO ₂ is conveyed into the processing apparatus, the pressure in the processing apparatus is set to 7.4 × 10 ⁶ Pa (75.2 kg / cm ² ) or more, and the temperature is set to 31.1 ° C. or more. To control each. The above conditions are values for transferring liquid CO ₂ to the supercritical state. A supercritical state is a state in which a liquid and a gas are in a single phase. The surface tension existing on the liquid surface is almost 0 (zero) in the supercritical state.

Therefore, by removing the supercritical liquid CO ₂ from the container 28 in the final stage, the device can be dried without impairing the upright orientation of the CNTs 12a. Here, liquid CO ₂ was used as a supercritical fluid, but instead of this, liquid nitrogen (N ₂ ), nitrous oxide (N ₂ O), xenon, sulfur hexafluoride (SF ₆ ), and the like were used. It can also be used. Also in the present embodiment example, similar to the third embodiment example, the same effect can be obtained by performing the drying step in an apparatus having a feedback function for controlling the pressure and temperature.

  By the way, when the device is further miniaturized and the hole diameter of the gate opening 17 is further reduced or the distance (depth) between the gate electrode 25 and the CNT film 12 is increased, the adhesive sheet does not reach the CNT film surface. CNT12a becomes difficult to be oriented upright. Actually, the CNT upright orientation after the formation of the gate structure mainly tends to make the CNTs 12a on the center side of the CNT film 12 in the gate opening 17 upright, and the uniformity of the upright orientation on the CNT film surface Is a factor that decreases. Such a tendency increases as the hole diameter of the gate opening 17 decreases. Actually, when the depth of the gate opening 17 is constant (15 μm) and the hole diameter is changed, when the hole diameter is 60 μm or more, it is possible to observe upright orientation of the CNTs 12a and an increase in emission current. In the case of 60 μm or less, almost no upright alignment of CNTs 12a and increase in emission current were observed.

  On the other hand, in the third and fourth embodiments, the CNTs 12a are oriented upright in advance, and the orientation is maintained until the final process. Therefore, it is necessary to perform the vertical alignment of the CNTs 12a with the adhesive sheet in the final process. Absent. Therefore, there is no restriction due to the hole diameter or depth of the gate opening 17, and the above-described problems such as a decrease in the uniformity of the upright orientation on the CNT film surface can be solved.

  Next, a fifth embodiment of the present invention will be described. FIG. 9 is a cross-sectional view showing the manufacturing method according to the present embodiment example, and (a) to (c) show each step step by step. The present embodiment example shows up to the process performed prior to the process of upright orientation of the CNTs 12a in the final stage, and is suitable when the insulating film 23 is formed on the CNT film 12 following the formation of the CNT film 12. It is a simple manufacturing method.

  That is, as shown in FIG. 9A, the CNT film 12 is fixed on the glass substrate 10 via the binder layer 14 in the same state as in FIG. At this time, many CNTs 12a that are vertically aligned are observed on the surface of the CNT film 12. Next, as shown in FIG. 9B, a liquid such as ethanol is sprayed on the CNT film 12, and the vertically aligned CNTs 12a are laid down by the surface tension of the liquid, and then the CNT film 12 is naturally dried. Let Subsequently, as shown in FIG. 9C, an acrylic resin, epoxy resin, polyimide resin, SOG (Spin on Glass) or the like is formed on the CNT film 12 as an insulating film 23 with a thickness of 20 μm by a spin coater. The baking process is performed.

  According to the above process of the present embodiment, the following problems when forming the insulating film 23 on the CNT film 12 can be solved. In other words, if the CNTs 12a are oriented upright on the surface of the CNT film 12, fine bubbles are dissolved in the CNT film 12 without being mixed with the binder solvent when the binder layer 14 is formed. There is a risk of causing problems such as bubbles and surface irregularities in the insulating film 23. For example, in the sample not according to this embodiment, bubbles are generated in the insulating film 23, the wettability between the CNT film 12 and the insulating film 23 during spin coating is not good, and the film thickness variation is 50. % Or more.

  On the other hand, according to the present embodiment, since the CNTs 12a are laid down and arranged prior to the binder solvent coating step and the insulating film forming step, the occurrence of the above-described problems is reliably suppressed, and the binder layer 14 and the insulating film 23 are prevented. Can be formed appropriately. For this reason, in the sample according to the present embodiment example, since the wettability was good, no bubbles were observed in the binder layer 14 or the insulating film 23, and a favorable result that the variation in film thickness was 5% or less was obtained. .

  By the way, in order to form a uniform and high-definition flat image display device using a field emission type cold cathode, it is necessary to arrange at least one electron source in each pixel. This corresponds to forming at least one or more vertically aligned CNTs in each pixel when a CNT film is used as an emitter.

Assuming that the area of one pixel is S (cm ² ), in order to arrange one or more upright aligned CNTs therein, the number density (number / number of upright aligned CNTs of 1 / S or more) There is a need to form a CNT film having cm ² ). For example, assuming a 30-inch high-definition television, one pixel has a rectangular shape of 0.01 cm × 0.03 cm. In that case, a CNT film having up to about 3333 CNTs / cm ² or more must be formed. It will not be.

  FIG. 10 is a graph showing the dependency of the pressure-sensitive adhesive sheet on the emission site number density. The horizontal axis represents the emission site number density, and the vertical axis represents the adhesive strength of the adhesive sheet. The measurement was performed with a bipolar structure of a CNT film and an anode electrode. The applied electric field is 3 V / μm.

When the adhesive sheet is not used (zero adhesive force), the site number density is about 2000 / cm ² . As the adhesive force increases, the number of sites tends to increase. With an adhesive force of 0.1 N / mm, uniform emission can be obtained over almost the entire surface (25000 N / mm). In addition, it was confirmed by a scanning electron microscope that the number density of emission sites observed under these conditions and the number density of CNTs oriented upright were substantially equivalent.

When a planar image device having one pixel of a rectangle having a size of 0.01 cm × 0.03 cm is produced using a CNT film in the case where the treatment with the adhesive sheet is not performed, the above-described conditions (about 3333 pieces / cm ^{Since 2} ) is not satisfied, many pixels that do not emit light are seen, resulting in an image with a lot of unevenness. Further, in the pixel that emits light, substantially one CNT functions as an electron source, so that the current fluctuation is large.

On the other hand, when a planar image device having a similar pixel size is produced using a CNT film in which CNTs are vertically oriented with an adhesive force of 0.004 N / mm, almost uniform light emission is observed from all pixels. It was done. This is because the CNT density (5000 / cm ² ) oriented with an adhesive force of 0.004 N / mm satisfies the condition of 3333 / cm ² or more. However, in this case, the light emission intensity varies greatly from pixel to pixel, resulting in a flickering image.

Furthermore, a planar image device having a similar pixel size was manufactured using a CNT film in which CNTs were vertically oriented with an adhesive force of 0.03 N / mm or more. As a result, uniform and high luminance light emission was obtained from all pixels. In addition, there was little variation in the emission intensity, and almost no flicker was observed. The density of CNTs oriented with an adhesive strength of 0.03 N / mm or more is 17000 / cm ² or more, which corresponds to about 5 times or more of the required conditions (3333 / cm ² or more).

  That is, about 5 or more vertically aligned CNTs exist per pixel. The low current fluctuation obtained here is because fluctuations in the electron current emitted from one CNT are statistically averaged by a plurality of CNTs. Such reduction in current fluctuation can be achieved by processing with a sheet having as much adhesive force as possible, but if a sheet of 0.03 N / mm or more is used, an image with almost no contact with the naked eye can be obtained. I was able to.

Therefore, in order to form a uniform and high-definition flat image display device, it is necessary to form a CNT film having a number density (pieces / cm ² ) of CNTs that are vertically oriented at least 1 / S or more. What is necessary is just to use the CNT film | membrane which has the number density (piece / cm < ² >) of CNT orientated orientated 5 / S or more.

  The number density condition of the vertically oriented CNTs described above is for the case where the CNT film exists over the entire pixel. However, in the case of the emitter of the triode structure, the ratio of the CNT film to the pixel is Reduced by other structures, ie gate electrodes. When the ratio of the area of the exposed CNT film to the area of the pixel is defined as the occupancy ratio r (%) of the CNT film, the above-described conditions are as follows.

That is, in order to form a uniform and high-definition flat pixel display device, it is necessary to form a CNT film having a number density (pieces / cm ² ) of CNTs in an upright orientation of at least 100 / (S × r) or more. It is necessary, and a CNT film having a number density (number / cm ² ) of vertically aligned CNTs of 500 / (S × r) or more may be preferably used.

  Although the present invention has been described based on the preferred embodiment thereof, the method for manufacturing the emitter of the present invention, the field emission cold cathode using the emitter, and the flat image display device have the same configuration as the above embodiment. However, the present invention is not limited thereto, and an emitter manufacturing method, a field emission cold cathode using the emitter, and a flat image display device using various modifications and changes from the configuration of the above embodiment are also within the scope of the present invention. included.

10: Glass substrate 11: Conductive layer 12: CNT film 12a: CNT
12b: Emitter 13: Insulating film 14: Binder layer 15: Cathode line 16: Gate electrode 17: Opening 18: Aluminum layer 19: Thin film 20: Adhesive material 21: Adhesive sheet 22: Metal fine particle 23: Insulating film 25: Gate electrode 27 : Etching solution 28: Container 29: Pure water

Claims (3)

Forming a CNT film constituting an emitter including a plurality of carbon nanotubes (CNT) on a substrate;
Forming an electrode on the CNT film via an insulating film;
Forming a plurality of openings in the electrode and the insulating film;
And erecting the CNTs on the surface of the CNT film in the opening,
An emitter manufacturing method characterized by the above.   A field emission cold cathode using the emitter manufactured by the method for manufacturing an emitter according to claim 1.   A flat image display device using the field emission cold cathode according to claim 2.

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