KR20030094490A - Method of manufacturing field emission display device using carbon nanotubes - Google Patents

Abstract

PURPOSE: A method is provided to prevent a leakage current and damages of carbon nanotube by coating the carbon nanotube with an insulating material. CONSTITUTION: A method comprises a step of forming a trench structure on a substrate through the use of a semiconductor process; a step of growing a carbon nanotube in the trench structure; a step of coating the substrate on which the carbon nanotube has grown with an insulating material; a step of drying the coated insulating material; and a step of planing the insulating material by using a lapping machine in such a manner that the thin film of the substrate is exposed.

Description

Method for manufacturing field emission device using carbon nanotubes {METHOD OF MANUFACTURING FIELD EMISSION DISPLAY DEVICE USING CARBON NANOTUBES}

The present invention relates to a method for manufacturing a field emission device using carbon nanotubes.

Field emission is the phenomenon in which electrons are tunneled from the surface of the conductor to the vacuum plane, which requires the application of an external electric field. The electric field to be applied to the metal emitter for the field emission is 3-7. Very high × 10 ⁷ V / cm, much research has been done to lower the electric field to be applied, and has generally been made in two directions. The first is to make the tip of the emitter sharper, and the second is to lower the work function of the emitter. The first method is to increase the field strength at the emitter end by increasing the field enhancement factor of the emitter. Initially, refractory metal was electrochemically etched and used as an emitter.

Carbon nanotubes are useful as field emission devices because of their very high aspect ratios of several nanometers in diameter. Although there are some differences depending on the carbon nanotubes, the field strengthening coefficients of the carbon nanotubes are about 2,500 to 10,000. Carbon nanotubes are also very hard and have excellent electrical conductivity, making them the most ideal material known to be a field emission array. It has an extremely thin tip (electron emitter at the end of the tube), making it suitable as an electron gun, and with the recent advances in the fabrication of carbon nanotube arrays on silicon or glass substrates, concerns about array difficulties have also disappeared. Since the application of FED is still in its infancy, optimization of the tip structure of carbon nanotubes and the arrangement of billions of tubes is being studied.

Application of carbon nanotubes as field emission devices employs a method in which carbon nanotubes synthesized by laser deposition are mixed with an adhesive material and applied to a substrate. This method uses single-walled carbon nanotubes to randomly spray carbon nanotubes onto a substrate.

In the method of applying to the substrate using the synthesized single-walled carbon nanotubes, the uniform field emission is affected by the uniformity of the coating of the carbon nanotubes, and the application of the carbon nanotubes is practically difficult to control. There is this. Depending on the location, the number of carbon nanotubes placed per unit area varies, which serves to reduce the uniformity of the field emission. In addition, the carbon nanotubes are made by mixing with the adhesive, so that continuous degassing is performed from the adhesive when the field is released, and this degassing causes the life of the field emission device to be shortened.

In addition, the application of carbon nanotubes as field emission devices uses a method of growing carbon nanotubes in a pattern or trench structure using chemical vapor deposition. In this method, carbon nanotubes are synthesized in selective regions divided into respective regions, and electrodes are placed on them, and have a structure similar to that of a triode structure using a conventional metal tip.

In the method of selectively growing carbon nanotubes in a trench structure by using chemical vapor deposition, there is a disadvantage that the trench structure must be made to a depth of at least 10 μm in order to achieve uniform height control due to the high growth rate of carbon nanotubes. However, grown nanotubes also have the disadvantage that they cannot fit at a uniform height. In addition, although carbon nanotubes grow with straightness, each carbon nanotube does not grow independently with straightness, resulting in contact with the substrate, resulting in leakage current in device fabrication. It will work.

The present invention has been made to solve the above problems,

SUMMARY OF THE INVENTION An object of the present invention is to fabricate a triode structured field emission device using carbon nanotubes, by applying an insulating material to the carbon nanotubes to enable insulation between the carbon nanotubes and the substrate, thereby preventing leakage current, and It is to provide a method for manufacturing a field emission device using carbon nanotubes with improved adhesion between nanotubes and a substrate.

Another object of the present invention is to provide a field emission device manufacturing method using carbon nanotubes to uniformly control the height of the carbon nanotubes coated with an insulating material in the fabrication of a field emission device having a triode structure using carbon nanotubes. It is.

In order to achieve the above object,

The present invention relates to a method of fabricating a field emission device having a triode structure using carbon nanotubes, wherein the carbon nanotubes are grown on a substrate using a semiconductor process, and an insulating material is applied to the substrate on which the carbon nanotubes are grown. It provides a method for producing a field emission device using carbon nanotubes.

Specifically, in the fabrication of a triode structured field emission device using carbon nanotubes, the carbon nanotubes are grown on a substrate using a semiconductor process, and SOG is applied to the substrate on which the carbon nanotubes are grown, followed by drying. Provided is a method of manufacturing a field emission device using carbon nanotubes.

In order to achieve the other object as described above,

The present invention provides a method for manufacturing a field emission device using carbon nanotubes by manufacturing a field emission device having a triode structure using carbon nanotubes by controlling the height of carbon nanotubes coated with an insulating material by a polishing machine. do.

Specifically, in the fabrication of a triode structured field emission device using carbon nanotubes, an electric field using carbon nanotubes for uniformly controlling the height of the carbon nanotubes by applying SOG and cutting them to have a uniform height by applying a grinder. Provided is a method of manufacturing an emitting device.

FIG. 1A is a schematic diagram showing an etching process of a silicon substrate during a manufacturing process of a field emission device using carbon nanotubes in this embodiment.

FIG. 1B is a schematic diagram showing a process of implanting a photosensitive agent onto a silicon substrate during the fabrication process of the field emission device using carbon nanotubes in the present embodiment.

FIG. 1C is a schematic diagram illustrating a process of depositing a catalyst metal for carbon nanotube synthesis and removing a photosensitive agent in a trench structure during a fabrication process of a field emission device using carbon nanotubes in this embodiment.

1D is a schematic diagram showing a growth process of carbon nanotubes on a substrate during the fabrication process of the field emission device using carbon nanotubes in the present embodiment.

FIG. 1E is a schematic diagram showing a process in which SOG, which is an insulating material, is applied to a substrate on which carbon nanotubes are grown during a manufacturing process of a field emission device using carbon nanotubes in this embodiment.

FIG. 1F is a schematic diagram showing a step of removing SOG, an insulating material, such that the carbon nanotubes have a length equal to the height of the trench structure by a fine polishing machine during the manufacturing process of the field emission device using the carbon nanotubes in the present embodiment. .

FIG. 1G is a schematic view showing a surface etching process using a hydrofluoric acid solution during the fabrication process of a field emission device using carbon nanotubes in this embodiment.

FIG. 1H is a schematic diagram showing a step of accelerating surface oxidation during the fabrication process of the field emission device using carbon nanotubes in the present embodiment.

FIG. 2A is a SEM photograph (5.0 kV 13.4 mm × 1.50 k, 30.0 um) showing carbon nanotubes synthesized without treatment of an insulating material in a silicon structure for a triode structure. FIG.

FIG. 2B is a SEM photograph (5.0 kV 12.1 mm × 3.50 k, 10.0 μm) showing carbon nanotubes synthesized without treatment of an insulating material in a silicon structure for a triode structure. FIG.

FIG. 3A is a SEM photograph (5.0 kV 12.2 mm × 1.50 k, 30.0 um) showing the SOG-treated carbon nanotubes in this example.

FIG. 3B is a SEM photograph (5.0 kV 12.9 mm × 10.0 k, 5.00 um) showing SOG-treated carbon nanotubes in this example.

Figure 4a is a SEM photograph (5.0kV 12.2mm x 5.00k, 10.0um) showing the surface of the carbon nanotubes processed by the polishing machine.

Figure 4b is a SEM photograph (5.0kV 13.0mm x 80.0k, 500nm) showing the surface of the carbon nanotubes processed by the polishing machine.

Figure 4c is a SEM photograph (5.0kV 13.0mm x 10.0k, 5.00um) showing the surface of the carbon nanotubes processed by the polishing machine.

FIG. 4D is a SEM photograph (15.0 kV 12.4 mm × 2.00 k, 20.0 μm) showing the surface of the carbon nanotubes processed with the polishing machine. FIG.

5 is a SEM photograph (5.0 kV 13.0 mm x 50.0 k) showing the degree of application of the SOG layer at a rotational speed of 2000 rpm in the present embodiment.

6 is a SEM photograph (5.0 kV 12.4 mm x 1.00 k) showing the degree of application of the SOG layer at a rotational speed of 200 rpm in the present embodiment.

FIG. 7A is a SEM photograph (5.0kV 12.8mm × 2.50k, 20.0um) showing a SOG layer coated on carbon nanotubes grown in a trench structure.

FIG. 7B is a SEM photograph (5.0 kV 12.6 mm × 3.00 k, 10.0 μm) showing an SOG layer coated on carbon nanotubes grown in a trench structure.

8 is a graph showing the effect of the field emission characteristics of the carbon nanotubes without the treatment of the insulating material.

9 is a graph showing the effect of the field emission characteristics of carbon nanotubes coated with SOG in the present embodiment.

Hereinafter, a method of manufacturing a field emission device using carbon nanotubes according to the present invention will be described in detail.

For the application of carbon nanotubes to the field emission device having a triode structure according to the present invention, as a detailed process,

Step (1): forming a structure in which a trench structure is arranged on a substrate using a semiconductor process;

Step (2): growing carbon nanotubes in the trench structure;

Step (3): applying an insulating material on the substrate on which the carbon nanotubes are grown;

Step (4): drying the applied insulating material; And

Step (5): grinding the insulating material to expose a thin film of the substrate using a polishing machine. Hereinafter, each step will be described in detail.

In the structure forming process in which the trench structure is arranged on the substrate in step (1), the structure of the silicon substrate is realized by using a conventional semiconductor process, and the silicon substrate is formed through a photolithography process and an etching process. A pattern for etching is formed on the substrate, and then the silicon substrate is etched in the depth direction. After depositing catalytic metal for carbon nanotube synthesis on the trench structure, the photoresist used as a sacrificial layer is removed.

The process of growing carbon nanotubes in the trench structure as step (2) is performed by synthesizing carbon nanotubes vertically aligned by a process of synthesizing carbon nanotubes on a substrate using a conventional semiconductor process.

In the step (3), the insulating material is applied onto the substrate on which the carbon nanotubes are grown, and the carbon nanotubes are grown on a device capable of rotating at a high speed, or the carbon nanotubes are grown. The insulating material is applied by a method of scanning the substrate with a dropper or the like, or the insulating material is applied by applying the two processes together.

MgO, Al ₂ O ₃ , SiO _2, etc. may be used as the insulating material, and include modifications that are easy for those skilled in the art.

The step (4) of drying the coated insulating material is carried out by drying the coated insulating material at a constant temperature to solidify the insulating material in a liquid state.

In the step (5), the step of flattening the insulating material to expose the thin film of the substrate using a polishing machine is performed by removing the insulating material coated and dried by the above process until the thin film of the silicon substrate is exposed by a fine polishing machine. Is done. Together with the removed insulating material, carbon nanotubes of non-uniform height will be uniform and have the same length as the height of the trench structure.

In addition, in order to enhance the field emission effect of the carbon nanotubes, surface etching is performed using an etching solution so that the carbon nanotubes buried in the coating layer of the insulating material are exposed to the outside.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the following examples, and various forms of embodiments can be implemented within the scope of the appended claims, and the following examples are only common to those skilled in the art to complete the present disclosure. It is intended to facilitate the implementation of the invention to those with knowledge.

EXAMPLE

In this embodiment, using SOG as an insulating material, while the substrate on which the carbon nanotubes are grown is rotated on a device capable of high-speed rotation, SOG is applied, and the applied SOG is dried at a constant temperature to dry and insulate the carbon nanotubes. An attempt was made to improve adhesion with the substrate.

SOG, also called Flowable Oxide, has a dielectric constant in the range of 3.9 to 5.0. In the present embodiment, FOX-16 sold by Dow Corning was used as a substance in which siloxanes or silicates were dissolved in an alcohol solvent.

First, as a structure implementing process in a silicon substrate, a pattern for etching the silicon substrate is formed on the substrate through a photolithography process and an etching process, and then the silicon substrate is etched in the depth direction. After depositing catalytic metal for carbon nanotube synthesis on the trench structure, the photoresist used as a sacrificial layer is removed. 1A shows an etching process of a silicon substrate. 1B shows a process of implanting a photosensitive agent on a silicon substrate. 1C shows a process for depositing a catalytic metal for carbon nanotube synthesis and removing a photoresist in a trench structure.

Next, carbon nanotubes vertically aligned are synthesized by synthesizing carbon nanotubes using a conventional semiconductor process on a substrate. 1D shows the growth process of carbon nanotubes on a substrate.

Next, SOG is applied to a substrate on which carbon nanotubes are grown. FIG. 1E illustrates a process in which SOG, an insulating material, is coated on a substrate on which carbon nanotubes are grown.

FIG. 3A is a SEM photograph (5.0 kV 12.2 mm × 1.50 k, 30.0 um) showing SOG-treated carbon nanotubes in this example, and FIG. 3B is a SEM photograph showing SOG-treated carbon nanotubes in this example. (5.0kV 12.9mm × 10.0k, 5.00um).

On the carbon nanotubes grown in the trench structure, SOG was applied at 1000 rpm or more using a spin coater device, which is a device capable of high-speed rotation. The thickness of the applied SOG layer varies with each rotational speed.

SOG was applied at a rotation speed of less than 1000 rpm. As the speed of rotation decreases, the coated SOG layer results in a thick coating.

5 is a SEM photograph (5.0kV13.0mm × 50.0k) showing the degree of application of the SOG layer at a rotational speed of 2000rpm, and FIG. 6 is a SEM photograph (5.0kV 12.4mm × 1.00k) showing the degree of coating of the SOG layer at a rotational speed of 200rpm. )to be.

Instead of using a spin coater to rotate the SOG, a certain amount was dropped using the dropper and then dried. In this case, it is thicker than the conventional rotation and completely covers the grown carbon nanotubes.

Rotary coatings and scanning coatings are made alone or together depending on the length of the carbon nanotubes. Since the length of the carbon nanotubes is usually about 50 μm, a process of applying a thickness of 50 μm or more is required. After application, the SOG is again applied by scanning onto the substrate without being rotated and dried.

FIG. 7A is a SEM photograph (5.0 kV 12.8 mm × 2.50 k, 20.0 um) showing the SOG layer coated on the carbon nanotubes grown in the trench structure, and FIG. 7B shows the SOG layer coated on the carbon nanotubes grown in the trench structure. SEM photograph shown (5.0 kV 12.6 mm x 3.00 k, 10.0 um). The result of the carbon nanotube substrate coated with the SOG layer as shown in FIG. 7 enables the polishing process to be uniform in the subsequent polishing process.

Next, in the process of drying the applied insulating material, the applied SOG layer is dried by heating at a temperature from room temperature to 300 ℃. The liquid SOG becomes a solid as the temperature is applied, and then serves as an insulating material.

Finally, the process of controlling the height of the carbon nanotubes coated with the insulating material by using a fine polishing machine. FIG. 1F is a process of removing the SOG, an insulating material, so that the carbon nanotubes have the same height as the height of the trench structure. Is displayed. The dried SOG-coated substrate is removed with a fine grinder until the silicon substrate is exposed. Together with the removed SOG, carbon nanotubes of non-uniform height will be uniform and have the same height as the height of the trench structure. 4A is a SEM photograph (5.0 kV 12.2 mm x 5.00 k, 10.0 um) showing the surface of the carbon nanotubes processed with the polishing machine, and FIG. 4B is a SEM photograph (5.0 kV 13.0) showing the surface of the carbon nanotubes processed with the polishing machine. mm × 80.0k, 500 nm), FIG. 4C is a SEM photograph (5.0 kV 13.0 mm × 10.0k, 5.00 um) showing the surface of the carbon nanotubes processed with the polishing machine, and FIG. 4D is the surface of the carbon nanotubes processed with the polishing machine. SEM photograph (15.0 kV 12.4 mm x 2.00 k, 20.0 um) showing

When surface etching using hydrofluoric acid solution to enhance the field emission effect of carbon nanotubes, the carbon nanotubes buried in the SOG coating layer will be exposed to the outside, and such exposure will result in high field emission density in subsequent device fabrication. It will have an effect. FIG. 1g illustrates a process of surface etching using a hydrofluoric acid solution, and FIG. 1h illustrates a process of accelerating surface oxidation following surface etching.

The reason why the hydrofluoric acid is adopted as the etching solution is because SOG is a component of SiO ₂ , and thus the etching in the hydrofluoric acid is easy, and the hydrofluoric acid is not limited thereto, and includes a modification that is easy for those skilled in the art.

[Comparative Example]

Carbon nanotubes grown in the trench structure were then subjected to experiments to control the length without SOG conditions.

FIG. 2A is a SEM photograph (5.0kV 13.4mm × 1.50k, 30.0um) showing carbon nanotubes synthesized without treatment of an insulating material in a silicon structure for a triode structure, and FIG. 2B is a silicon structure for a triode structure SEM photograph (5.0kV 12.1mm × 3.50k, 10.0um) showing carbon nanotubes synthesized without treatment of insulating material in the body.

The grown carbon nanotubes do not have a uniform height as shown in Figs. 2a and 2b, and in this case, the triode structure because the grown carbon nanotubes are grown to a height beyond the trench structure despite the change in the synthesis time. It acts as a factor that makes it difficult to be applied as a field emission device.

The field emission characteristics of the carbon nanotubes were measured in Examples and Comparative Examples, respectively. 8 is a graph showing the effect of the field emission characteristics of the carbon nanotubes without the treatment of the insulating material, Figure 9 is a graph showing the effect of the field emission characteristics of the carbon nanotubes coated with SOG.

As a result of SOG treatment, stable field emission characteristics and low emission voltages were observed, and stability over time could be measured.

The present invention, in the fabrication of a triode structured field emission device using carbon nanotubes, by applying an insulating material to the carbon nanotubes to enable insulation between the carbon nanotubes and the substrate to prevent leakage current, during the polishing process It prevents damage to the carbon nanotubes, maintains the adhesion between the carbon nanotubes and the substrate, and improves the stability in measuring the field emission.

The present invention also provides a field emission device having a triode structure using carbon nanotubes, by uniformly controlling the height of the carbon nanotubes, thereby facilitating control of the length during growth of the carbon nanotubes, thereby providing uniform field emission characteristics. Implement and achieve the convenience of the process.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it is possible to make various modifications or variations without departing from the spirit and scope of the invention. Accordingly, the appended claims will cover such modifications and variations as fall within the spirit of the invention.

Claims (7)

In the method for manufacturing a field emission device having a triode structure using carbon nanotubes, A structure forming step (S1) in which trench structures are arranged on a substrate using a semiconductor process; Growing carbon nanotubes in the trench structure (S2); Applying an insulating material on the substrate on which the carbon nanotubes are grown (S3); Drying the applied insulating material (S4); And And a step (S5) of planarizing the insulating material so that the thin film of the substrate is exposed by using a polishing machine. The method of claim 1, The step S3 is a method of manufacturing a field emission device using carbon nanotubes, characterized in that further comprising the step (S3-1) of applying an insulating material to the substrate on which the carbon nanotubes are grown. The method of claim 1, The step S3 is a method of manufacturing a field emission device using carbon nanotubes, characterized in that it further comprises the step (S3-2) of coating the insulating material on the substrate on which the carbon nanotubes are grown. The method of claim 1, The step S4 is a method for producing a field emission device using carbon nanotubes, characterized in that the drying by heating to room temperature to 300 ℃. The method of claim 1 The step S5 is a method of manufacturing a field emission device using carbon nanotubes, characterized in that further comprises the step (S5-1) of surface etching using an etching solution. The method of claim 5, The etching solution is a field emission device manufacturing method using carbon nanotubes, characterized in that the hydrofluoric acid solution. The method according to any one of claims 1 to 6, The insulating material is a method for producing a field emission device using carbon nanotubes, characterized in that the SOG.