JP2018003068A - Manufacturing method of metal nanoparticle sintered film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a metal nanoparticle sintered film fine in fusion of metal particles, good in adhesiveness to a substrate and capable of mass production of a sintered film exhibiting sufficient conductivity by sintering metal nanoparticles each other by light irradiation in ultra short time.SOLUTION: There is provided a method for making a film exhibiting good conductivity by enhancing a fine fusion of metal particles and adhesiveness of a substrate by sintering a coated film containing metal nanoparticles by flash light irradiation in short time, further a method of a semiconductor element, a thin film transistor and an electronic device including the method for making the film.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a metal nanoparticle sintered film. In particular, the present invention relates to a method for producing a metal nanoparticle sintered film formed by sintering nanometer-sized metal fine particles by flash light irradiation.

  In recent years, organic electronic devices such as thin film transistors (TFTs) have attracted attention by printing, and can add value such as light weight, flexibility, and large screen, which is difficult with conventional Si semiconductors. Development of materials (pastes) and printing methods (processes) has been actively promoted for practical application. In particular, achieving a large screen (miniaturization) of a device requires a particularly low surface resistance for the device and its wiring because of the surface uniformity of the current.

  Therefore, research and development of circuits using nanometer-sized metal particles are being actively conducted. Nanometer-sized metal fine particles are known to have physical and chemical properties different from those of bulk materials. For example, the nanoparticles have characteristics such as a low melting point and a low sintering temperature compared to the bulk material and high strength. Furthermore, since the characteristics of the nanoparticles can be controlled by controlling the particle size, it is possible to expect higher functionality of predetermined characteristics depending on the control method. As a conventional manufacturing method for manufacturing a nanoparticle sintered body by sintering nanometer-sized fine particles, a method of performing heat treatment in the air or in a predetermined gas atmosphere using an electric furnace or the like is known.

  For example, after applying a dispersion in which metal nanoparticles having an average particle diameter of 1 to 100 nm whose surface is coated with alkylamine is dispersed in an organic solvent having a boiling point of 100 ° C. or higher, a pressurized atmosphere of 1.5 to 10 atm. The metal nanoparticle sintered body is formed by forming a metal nanoparticle sintered body by efficiently releasing the alkylamine covering the surface of the metal nanoparticle by heat treatment at a temperature of 100 ° C to 200 ° C. A method is known (for example, refer to Patent Document 1).

However, according to the method for producing a metal nanoparticle sintered body described in Patent Document 1, in the step of applying a dispersion containing metal nanoparticles whose surface is coated with an alkylamine to a base material and sintering it, 1 × 10 ^-5 Ω · cm (hereinafter referred to as 1E-05 Ω · cm) In order to obtain a conductivity of not more than 150 ° C. for 30 minutes in a pressurized atmosphere of 1.5 to 10 atm. . Further, the silver fine particles fired at a low temperature for a short time shown in Patent Document 2 also require a treatment at 140 ° C. for 90 seconds. Accordingly, when heat treatment is performed by printing or coating on an inexpensive and low heat resistant support such as a PET film, the metal nanoparticles cannot be sufficiently sintered due to shrinkage and deformation of the support due to heat. In addition, the long sintering time is not suitable for high speed and mass production, and has a problem of high cost.

JP 2009-88340 A JP 2011-202265 A

  In order to solve such a conventional problem, the present invention sinters metal nanoparticles by light irradiation in an extremely short time, and can sinter metal nanoparticles capable of mass-producing a sintered film exhibiting sufficient conductivity. It is to provide a method for producing a conjunctiva.

  As a result of intensive studies to solve the above problems, the inventors of the present invention have made a dense fusion of metal particles and a base material by sintering a coating film containing metal nanoparticles by flash light irradiation in a short time. As a result, the inventors have found a method for producing a film that exhibits good electrical conductivity, and a method for producing a semiconductor element, a thin film transistor, and an electronic device including the film forming method, and have completed the invention.

  That is, the present invention is a method for producing a metal nanoparticle sintered film in which a paste containing metal nanoparticles is applied to the surface of a substrate to form a coating film, and sintered by flash light irradiation.

  The method for producing a sintered metal nanoparticle film, wherein the single irradiation time of the flash light irradiation is 10 ms or less.

The method for producing a metal nanoparticle sintered film, wherein an energy density applied to the coating film by the flash light irradiation is 1.9 J / cm ² or more.

  The metal nanoparticle has an average particle diameter of 1 μm or less, and a method for producing a metal nanoparticle sintered film including particles made of metal selected from the group consisting of gold, silver, and copper.

  The coating film is formed by spin coating, bar coating, slot die coating, blade coating, painting, dip pen, syringe, air brush, lithography, screen printing, inkjet printing, gravure printing, gravure offset printing, letterpress reverse printing, laser printing. A method for producing a sintered metal nanoparticle film selected from the group consisting of xerographic printing, pad printing, and combinations thereof.

  The manufacturing method of the organic-semiconductor element containing the manufacturing method of the said metal nanoparticle sintered film, an organic transistor, and an electronic device. It is about.

  According to the method for producing a metal nanoparticle sintered film according to the present invention, it is possible to provide a method for producing a metal nanoparticle sintered film in which the whole film is dense and has good adhesion to a substrate.

It is a scanning electron micrograph of the sintered film which sintered.

  Details of the present invention will be described below.

  The method for producing a metal nanoparticle sintered film according to the present invention comprises first preparing a paste containing metal nanoparticles, applying the paste to a substrate by any method to form a coating film, and sintering nanometer-sized metal fine particles. This is a method for producing a sintered layer as a nanoparticle sintered film.

  The metal nanoparticle paste is composed of metal nanoparticles, a solvent, a dispersant, a protective agent, and the like.

  As metal nanoparticles, for example, metal particles such as gold, silver, copper, nickel, zinc, aluminum, calcium, magnesium, iron, platinum, palladium, tin, chromium, lead, and these metals such as silver / palladium. Alloys: Thermally decomposable metal compounds that thermally differentiate at relatively low temperatures, such as silver oxide, organic silver, and organic gold, to give conductive metals; conductive metal oxide particles such as zinc oxide (ZnO) and indium tin oxide (ITO) Etc. can be used.

  The type of the solvent (dispersion medium) is not particularly limited, but water or an organic solvent capable of dissolving or dispersing the conductive material can be appropriately selected. Specifically, for example, water, aliphatic hydrocarbon-based, aromatic hydrocarbon-based, alcohol-based, ketone-based, ether-based, ester-based and other organic solvents or some or all of these intramolecular hydrogens are fluorinated. Can be used. These may be used alone or in combination of two or more.

  In addition to the conductive material and the solvent (dispersion medium), the metal nanoparticle paste includes a binder component such as a resin, an antioxidant, various catalysts for promoting film formation, and a silicone surfactant, as necessary. Alternatively, various surfactants such as a fluorosurfactant, a leveling agent, a release accelerator, and the like can be added.

  The metal nanoparticle paste is mixed with a cationically polymerizable compound such as an oxetane compound, an epoxy compound or a vinyl ether compound, or a radically polymerizable compound such as a compound containing a vinyl group or a (meth) acryloyl group, followed by thermosetting. Or an active energy ray-curable paste such as ultraviolet rays or electron beams.

  As the metal nanoparticles, it is preferable to use metal particles of 1 μm or less because an arbitrary image line can be formed with a narrower line width and a conductor can be formed by sintering at a lower temperature.

In preparing a paste using such conductive metal particles of the order of nm, a binder component that is relatively stable near room temperature but can form a conductor by sintering at a relatively low temperature of 150 ° C. or less. It is preferable to use conductive metal particles coated with. The binder component may function as a protective material or dispersant for the conductive metal particles. Examples of materials that can be used as such a binder component include linear or branched polyethyleneimine, polyethyleneimine-polyalkylene glycol copolymers, N-oxidized derivatives thereof, and N-acetyl derivatives thereof. Derivatives, cationic resins such as polyvinyl-2-pyrrolidone, anionic resins such as polyalkylene glycol mono (meth) acrylate / (meth) acryloyloxyalkyl acid phosphate copolymers, alkanethiols, monoalkyls Mention may be made of alkylamines including amines, dialkylamines or trialkylamines.

  As the metal nanoparticle paste, it is necessary to use a paste manufactured by a formulation devised so that the particle diameter is uniform, or a paste from which coarse particles are removed by centrifugation or filtration in the production of an electronic device to be described later. In terms of smoothing the interface on the semiconductor layer side of the source electrode and drain electrode and the interface on the insulating film side of the gate electrode, it is preferable for manufacturing an electronic device. However, the wide particle size distribution of the metal nanoparticles does not limit the sintering method of the present invention.

  As a method for forming a conductive coating film of the present invention, a coating film forming method selected from the group consisting of spin coating, bar coating, slot die coating, blade coating, painting, dip pen, syringe, airbrush, lithography, and combinations thereof Can be used. As other coating film forming methods, screen printing, inkjet printing, gravure printing, gravure offset printing, relief printing, laser printing, xerography printing, pad printing, and printing selected from the group consisting of these combinations A coating film can also be produced using the method. In particular, gravure offset printing and letterpress reverse printing can cause the transferred material to absorb the solvent in the metal paste, thereby reducing the amount of solvent in the metal nanoparticle paste. Therefore, the coating film surface unevenness | corrugation defect resulting from the volatilization of the solvent at the time of sintering can be suppressed. Therefore, it is suitable for sintering by high intensity energy irradiation.

  There is no limitation on the support applicable to the formation of the conductive coating film of the present invention. For example, silicon, a thermally oxidized film silicon whose surface is oxidized to be an insulating layer, glass, a metal such as stainless steel on which an insulating layer is formed. Thin plate: Plastic films such as polycarbonate (PC), polyethylene terephthalate (PET), polyimide (PI), polyethersulfone (PES), polyethylene naphthalate (PEN), liquid crystal polymer (LCP), polyparaxylylene, cellulose; A composite film obtained by adding a gas barrier layer and a hard coat layer to a plastic film can be used. Especially, a plastic film can be used suitably as a support body from a flexible viewpoint. Moreover, although there is no restriction | limiting in the thickness of the said support body, it is preferable that a thickness is 150 micrometers or less from the point of a softness | flexibility or weight reduction.

  The thin film transistor of the present invention can employ any method for forming a source electrode, a drain electrode, or a gate electrode. The thin film transistor of the invention is manufactured in the following steps. That is, the method includes a step of forming a gate electrode, a step of forming an insulating layer, a step of forming a source electrode and a drain electrode, and a step of forming an organic semiconductor layer in contact with the insulating layer over a support.

  The thin film transistor of the present invention can have horizontal and vertical transistor structures. As the lateral transistor, for example, a bottom-gate (BG) or top-gate (TG) transistor defined by the positional relationship of the gate electrode with the transistor component can be used. Further, depending on the positional relationship between the source / drain electrodes and the organic semiconductor layer in each of the BG type and the TG type, a transistor structure such as a bottom contact type, a top contact type, and a bottom top contact type can be adopted.

  When a bottom gate type thin film transistor is manufactured as a thin film transistor structure, a gate electrode pattern is formed on a support and sintered, an insulating layer is formed, and a source electrode and a drain electrode pattern are formed on the insulating layer. What is necessary is just to sinter. In the case of manufacturing a top gate type thin film transistor, a source electrode and a drain electrode are formed on a support and sintered, then an insulating layer is formed, and a gate electrode is formed on the insulating layer and sintered. That's fine.

  The material (insulating material) of the insulating layer of the thin film transistor of the present invention only needs to contain an insulating material. For example, an epoxy resin, a polyimide resin, a polyvinylpyrrolidone resin, a polyvinyl alcohol resin, an acrylonitrile resin, Methacrylic resin, polyamide resin, polyvinyl phenol resin, phenol resin, polyamideimide resin, fluorine resin, melamine resin, urethane resin, polyester resin, alkyd resin, and the like can be applied. In addition, these may be used alone or in combination of two or more, and if necessary, constitutions such as high relative dielectric constant particles such as alumina fine particles, silica fine particles and tantalum oxide fine particles, and low relative dielectric constant particles such as hollow silica fine particles Ingredients may be added. There is no restriction | limiting in the solvent which can be used for an insulating material, For example, various organic solvents, such as water, hydrocarbon type, alcohol type, ketone type, ether type, ester type, glycol ether type, a fluorine type, can be used. Moreover, binder components, such as resin, antioxidant, a leveling agent, a mold release accelerator, and various catalysts for film formation promotion can be used as needed.

  The electrode coating film used for the thin film transistor is selected from the group consisting of screen printing, inkjet printing, gravure printing, gravure offset printing, relief printing, laser printing, xerographic printing, pad printing, and combinations thereof. The coating film can be formed using a printing method. In particular, gravure offset printing and letterpress reverse printing can cause the transferred material to absorb the solvent in the metal paste, thereby reducing the amount of solvent in the metal nanoparticle paste. Therefore, the coating film surface unevenness | corrugation defect resulting from the volatilization of the solvent at the time of sintering can be suppressed. In addition, the printing method is suitable in that high-definition and high-smooth electrode production is easy and mass production is possible.

  Hereinafter, “a member to be transferred having a releasability provided with an ink line portion corresponding to a source electrode, a drain electrode or a gate electrode made of a conductor” is referred to as an “ink image line portion-shaped transfer member”. , “The ink image line portion corresponding to the source electrode, drain electrode or gate electrode” may be referred to as “the electrode image forming ink image line portion”.

  The gravure offset printing method uses a gravure plate in which a concave portion (having the same pattern as the image line) corresponding to the image line of the source electrode, the drain electrode or the gate electrode is formed, and a member to be transferred having releasability. A step of filling a gravure plate with a metal nanoparticle paste, and transferring the metal nanoparticle paste filled into the recess to the surface of a transferable member having a releasability, thereby forming an ink image area forming transfer member And contacting the electrode forming ink image forming portion formed on the ink image forming portion transfer member with a support such as a substrate, and transferring the ink forming image forming portion to the support. A printing method comprising the steps of:

  The letterpress reverse printing method uses a letterpress on which a convex part corresponding to the reverse pattern of the source electrode, drain electrode or gate electrode is formed, and a member to be transferred having releasability. A step of applying a metal nanoparticle paste to the surface of the member to be transferred, and an ink portion corresponding to a reversal pattern of the source electrode, drain electrode or gate electrode by pressing the relief plate on the member to be transferred to which the paste has been applied For forming an electrode by bringing a transfer member formed on the relief printing plate into contact with a support member such as a substrate and an ink image line-shaped transfer member produced by removing the reverse pattern pressed by the relief printing plate. And a step of transferring an ink image line portion to a support.

  That is, in the letterpress reverse printing method, the letterpress has a convex part of a reverse pattern of a desired image line part. Thus, by transferring the ink portion corresponding to the inverted pattern of the source electrode, drain electrode or gate electrode onto the relief plate, the image area corresponding to the source electrode, drain electrode or gate electrode that was not pressed by the relief plate is obtained. It remains on the member to be transferred having releasability. Since the member to be transferred has releasability, the member to be transferred having the releasability provided with the image line corresponding to the source electrode, the drain electrode or the source electrode is supported on a substrate or the like. By making contact with the body, the image area is transferred to the support.

  In the method of manufacturing a thin film transistor of the present invention, as a printing method for forming an image line portion with conductive ink corresponding to the source electrode and the drain electrode, an ink image line portion with a narrower line width and a thinner film thickness can be formed. Compared with the gravure offset printing method, the letterpress reverse printing method is preferred.

  In the letterpress inversion printing method, the adopted electrode width in the laminated section of the thin film transistor is not different in the thickness direction, and a source electrode and a drain electrode with no transfer abnormality can be obtained. A thin film transistor having such a source electrode and a drain electrode is a thin film transistor with less variation in mobility and threshold voltage when driven.

  Specifically, the source electrode and the drain electrode have the same electrode thickness, both of which are made of a conductor having a thickness of 150 nm or less, preferably 50 to 100 nm, and having an appropriate electrode shape having no abnormality such as a concave shape or a convex shape. A source electrode and a drain electrode can be easily obtained. As a result, such a transistor has improved film thickness and crystal uniformity of the upper semiconductor layer, and becomes a thin film transistor with less variation in mobility and threshold voltage when driven as a thin film transistor. Such excellent features are the features of transfer printing described above, which cannot be achieved by conventional printing methods such as screen printing and ink jet printing.

  The support used in the thin film transistor of the present invention is not limited. For example, silicon, a thermally oxidized film silicon whose surface is oxidized to be an insulating layer, glass, a metal thin plate such as stainless steel on which an insulating layer is formed; polycarbonate (PC ), Polyethylene terephthalate (PET), polyimide (PI), polyethersulfone (PES), polyethylene naphthalate (PEN), liquid crystal polymer (LCP), polyparaxylylene, cellulose and other plastic films; gas barriers on these plastic films A composite film provided with a layer or a hard coat layer can be used. Especially, a plastic film can be used suitably as a support body from a flexible viewpoint. Moreover, although there is no restriction | limiting in the thickness of the said support body, it is preferable that a thickness is 150 micrometers or less from the point of a softness | flexibility or weight reduction.

  For the production of the sintered film of the present invention, a method of sintering by irradiating flash light onto the nanometal paste coating film can be employed.

  Furthermore, near / mid-infrared light irradiation, laser light irradiation, or a plasma processing method can be used in combination in the step of obtaining a sintered film in the present invention.

  In the method for producing a sintered film using flash light in the present invention, xenon, helium, neon, and argon can be used as the light source of the flash light, but xenon is preferably used. The xenon lamp light is not particularly limited. However, since the light has a continuous optical distribution from an ultraviolet ray having a wavelength of 300 nm to an infrared ray having a wavelength of 1000 nm, when using a support that absorbs ultraviolet rays, It is desirable to cut the wavelength. This is to prevent heat generation and deterioration of the support accompanying ultraviolet absorption.

The number of times of light irradiation may be one time or a plurality of times, and the single irradiation time of the xenon lamp is preferably 10 ms or less. In order to sinter a coating film having a large area, multiple times of light irradiation are more preferable in that in-plane sintering is performed uniformly. Moreover, in order to irradiate flash light at a high frequency, it is better that the single irradiation time is shorter.
The irradiation condition of the flash light shows a volume resistivity of 1.5E + 01 Ω · cm when the sintered film thickness is 100 nm and the density of the irradiation energy applied to the coating film is 1.9 J / cm ² , and 8 When it was 0.4 J / cm ² , 4.7E-06 Ω · cm was exhibited, and therefore it is preferable to give an irradiation energy of 1.9 J / cm ² or more. At this time, the same effect can be obtained by single irradiation or pulse irradiation.

In the sintered film forming process of the present invention, energy irradiation can be performed not only from the coating film or electrode coating film side but also from the support side that is not the coating film or electrode coating film side. It can also irradiate and sinter from the both sides of a side and a support body side.

  The sintered film forming step of the present invention can be carried out in the atmosphere, and can also be carried out in an inert gas atmosphere such as argon, nitrogen, helium.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. In the following examples and comparative examples, “part” and “%” are both based on mass.

  A method for preparing the sample and a method for measuring physical properties and the like are as follows.

(Metal nanoparticle paste)
Dispersion RAGT (manufactured by DIC Corporation) in which silver nanoparticles coated with a polyethyleneimine polymer having an average molecular weight in the range of 10,000 to 30,000 are dispersed in an ethanol solvent to a concentration of 10 to 20%. Was used as a metal nanoparticle paste.

(Measurement method of coating film and sintered film thickness)
The film thickness was measured using a scanning white interference microscope (manufactured by Ryoka System).

(Method of flash photosintering)
As the xenon flash sintering apparatus used in the present invention, a strobe flash apparatus for heat source (manufactured by Ebara Laboratories Co., Ltd.) for single flash system heat treatment evaluation was used. The sintering apparatus is an apparatus capable of irradiating energy with a maximum intensity of 10 J / cm ^{2 in} a range of 30 mm.

(Method for measuring volume resistivity of sintered film)
The volume resistivity was measured with a low resistivity meter Lorester EP (manufactured by Mitsubishi Chemical Corporation) using a four-terminal measurement method. The volume resistivity was determined from the film thickness of the conductive film of the test piece. In addition, the volume resistivity was shown by the method of describing 8.8 * 10 < ^-6 > ohm * cm as "8.8E-06 ohm * cm", for example.

(Measurement of energy density during flash light irradiation)
The amount of energy and energy density given to the substrate by flash light irradiation were adjusted by adjusting the distance from the light source to the coating film. The amount of energy and energy density given to the substrate by light irradiation were measured with a laser power meter (made by Offiel).

(Sintering method of coating film)
Thermal sintering, which is a conventional method, was performed by sintering the coating film produced by the above method in a constant temperature / dryer (manufactured by Clean Oven DE411 Yamato Kagaku) at 180 ° C. for 30 minutes.

(Scanning electron microscope observation)
The electron micrograph was taken with an operation electron microscope JSM-7500TFE (manufactured by JEOL). The acceleration voltage at the time of photographing was 2 kV (GB-H mode). The measurement magnification was 10,000 times and 50,000 times.
[Example 1]

(Preparation and evaluation of nano metal paste coating film)
(1) Preparation of nano metal paste coating film by spin coating In this experiment, 0.5 mL of metal nano paste was dropped on a 0.7 mm thick non-alkali glass substrate (40 mm × 50 mm), and the film thickness after sintering A coating film was prepared by spin coating at a rotation speed (about 500 to 2000 rpm) adjusted to a thickness of 100 nm.
(2) Sintering of coating film by flash light irradiation A sintered film was prepared by irradiating flash light to the obtained coating film. The discharge energy of the flash light irradiation apparatus was fixed at 6000 J / F, and the voltage was 862V. By adjusting the discharge coil, the peak half-value width of the flash time was 0.8 ms. The flash light was applied to the coating film once.
Adjustment of the light irradiation energy to the coating film was performed by adjusting the distance from the light source to the coating film. The distance from the light source to the coating film was set to 30, 40, 50, 60, 70, 80, 90, 100 and 130 mm. The energy density given to the coating film at this time is shown in Table 1.
(3) Evaluation of nano metal paste coating film The volume resistivity of the obtained sintered film was determined by a low resistivity meter using a four-terminal measurement method.
(Comparative Example 1)

(1) Preparation of nano metal paste coating film by spin coating In this experiment, 0.5 mL of metal nano paste was dropped on a 0.7 mm thick non-alkali glass substrate (40 mm × 50 mm), and the film thickness after sintering A coating film was prepared by spin coating at a rotation speed (about 500 to 2000 rpm) adjusted to a thickness of 100 nm.
(2) Sintering of coating film by heat The obtained coating film was sintered at 180 ° C. for 30 minutes by a constant temperature / dryer to obtain a sintered film.
(3) Evaluation of nano metal paste coating film The volume resistivity of the obtained sintered film was determined by a low resistivity meter using a four-terminal measurement method.

Table 1 shows the surface resistance and volume resistivity of the sintered films obtained in Example 1 and Comparative Example 1. In the sintering method using the xenon lamp of the present invention, conductivity was developed by irradiating the substrate with energy of 1.9 J / cm ² and a volume resistivity of 1.6E + 01Ω · cm was exhibited. A volume resistivity of 4.7E-06 Ω · cm was exhibited by energy irradiation of 8.4 J / cm ² . The above results show that the conductivity becomes 1 million times or more by light irradiation of 0.8 ms.

On the other hand, the thermal sintering method shown in Comparative Example 1 showed a volume resistivity of 2.6E-05 Ω · cm. This volume resistivity was not observed even when the firing time was increased.
[Example 2]

(Preparation and evaluation of nano metal paste coating film)
(1) Production of nano metal paste coating film by letterpress reverse printing method In this experiment, letterpress reverse printing method using a glass slit coater on a 0.7 mm thick non-alkali glass substrate (40 mm × 50 mm) -57118), a coating film was prepared by printing the entire surface of the metal nano paste on the support.
(2) Sintering of coating film by flash light irradiation A sintered film was prepared by irradiating flash light to the obtained coating film. The discharge energy of the flash light irradiation apparatus was fixed at 6000 J / F, and the voltage was 862V. By adjusting the discharge coil, the peak half-value width of the flash time was 0.8 ms. The flash light was applied to the coating film once.
Adjustment of the light irradiation energy to the coating film was performed by adjusting the distance from the light source to the coating film. The distance from the light source to the coating film was set to 30, 40, 50, 60, 70, 80, 90, 100 and 130 mm. The energy density given to the coating film at this time is shown in Table 1.
(3) Evaluation of nano metal paste coating film The volume resistivity of the obtained sintered film was determined by a low resistivity meter using a four-terminal measurement method.
(Comparative Example 2)

(1) Production of nano metal paste coating film by letterpress reverse printing method In this experiment, letterpress reverse printing method using a glass slit coater on a 0.7 mm thick non-alkali glass substrate (40 mm × 50 mm) -57118), a coating film was prepared by printing the entire surface of the metal nano paste on the support.
(2) Sintering of the coating film by heat The obtained coating film was sintered at 180 ° C. for 30 minutes with a constant temperature / dryer to obtain a sintered film.
(3) Evaluation of nano metal paste coating film The volume resistivity of the obtained sintered film was determined by a low resistivity meter using a four-terminal measurement method.

The surface resistance and volume resistivity of the sintered films obtained in Example 2 and Comparative Example 2 are shown in the lower part of Table 1. In the sintering method using the xenon lamp of the present invention, conductivity was developed by irradiating the substrate with energy of 1.9 J / cm ² , and a volume resistivity of 1.8E + 01Ω · cm was exhibited. A volume resistivity of 5.0E-06 Ω · cm was exhibited by energy irradiation of 8.4 J / cm ² . The above results show that the conductivity becomes 1 million times or more by light irradiation of 0.8 ms.

On the other hand, the thermal sintering method shown in Comparative Example 2 showed a volume resistivity of 2.3E-05 Ω · cm. This volume resistivity was not observed even when the firing time was increased.

(Electron microscope observation of sintered film)
Scanning electron micrographs of the sintered films obtained by heat (1 and 2 in FIG. 1) or flash light irradiation (3 and 4 in FIG. 1) are shown in FIG. On the surface of the sintered film obtained by thermal sintering, coarse silver particles having a particle diameter of 20 nm to 200 nm were observed in the coating film. Silver independent particles are not observed on the surface of the sintered film obtained by sintering by flash light irradiation, and the particles are fused and bulked. It is considered that the smooth coating film surface without coarse particles was obtained in addition to high conductivity by bulking by fusion.
[Example 3]

(Production and evaluation of TFT elements)
Based on the sintered film substrate obtained in Example 1, a test element of a thin film transistor having a BGBC type structure was produced by the following procedure.
(1) Fabrication of gate electrode Cr was fabricated on a non-alkali glass substrate having a thickness of 0.7 mm by patterning a predetermined gate electrode pattern on the substrate by vapor deposition. In this experiment, a Cr deposited film was used for the gate, but a metal nano paste patterned using a relief printing method can also be used as the gate electrode.
(2) Production of Insulating Layer In this experiment, a solution in which a styrene acrylic acrylate resin was dissolved at 10 to 15 wt% in a polypropylene glycol monomethyl ether acetate solution was dropped on a glass substrate on which a gate electrode was formed, and 700 by spin coating. The film was applied to a thickness of ˜800 nm. The insulating layer was produced by irradiating the obtained substrate with ultraviolet rays and curing it.
(3) Production of Source Electrode and Drain Electrode In this experiment, the source electrode and the drain electrode were produced by forming a pattern using relief printing on a support on which a gate electrode and an insulating layer were formed. The source electrode and drain electrode patterns produced by letterpress reverse printing were produced with a channel length of 20 μm and a channel width of 100 μm. The electrode film thickness was made to be 100 nm after sintering.
(4) Electrode Sintering The support on which the source electrode and drain electrode patterns were formed was irradiated with xenon flash light from a distance of 30 mm from the light source to sinter the source and drain electrode patterns to obtain the electrodes. . At this time, the energy density given to the support was 8.4 J / cm ² .
(5) Electrode surface treatment The electrode surface is treated by immersing the support on which the gate electrode, insulating film, source electrode and drain electrode are formed in an isopropyl alcohol solution of 30 mmol / L pentafluorobenzenethiol for 20 minutes. It was. Immediately after immersion, the substrate was washed with isopropyl alcohol.
(6) Formation of semiconductor layer An organic semiconductor was used as the semiconductor for producing the TFT element. As the organic semiconductor used in this experiment, a p-xylene solution of 0.4 wt% C10-BTBT-yne-PhC5 was used. The TFT element was produced by drop casting the organic semiconductor solution to the channel portion between the source electrode and the drain electrode. After drop casting the semiconductor solution, the solvent p-xylene was evaporated at room temperature.
(7) Evaluation of TFT characteristics The fabricated element was subjected to heat treatment in the atmosphere at 80 ° C. for about 10 minutes, and then measured for Id-Vg and Id-Vd characteristics using a semiconductor parameter measuring device (Keithley 4200). The field effect mobility and the ON / OFF ratio were determined by a known method. The unit of field effect mobility is cm ² / Vs.
(Comparative Example 3)

In implementation, a thin film transistor test element having a BGBC type structure was fabricated in the following procedure.
(1) Fabrication of gate electrode Cr was fabricated on a non-alkali glass substrate having a thickness of 0.7 mm by patterning a predetermined gate electrode pattern on the substrate by vapor deposition. In this experiment, a Cr deposited film was used for the gate, but a metal nano paste patterned using a relief printing method can also be used as the gate electrode.
(2) Production of Insulating Layer In this experiment, a solution in which a styrene acrylic acrylate resin was dissolved at 10 to 15 wt% in a polypropylene glycol monomethyl ether acetate solution was dropped on a glass substrate on which a gate electrode was formed, and 700 by spin coating. The film was applied to a thickness of ˜800 nm. The insulating layer was produced by irradiating the obtained substrate with ultraviolet rays and curing it.
(3) Production of Source Electrode and Drain Electrode In this experiment, the source electrode and the drain electrode were produced by forming a pattern using relief printing on a support on which a gate electrode and an insulating layer were formed. The source electrode and drain electrode patterns produced by letterpress reverse printing were produced with a channel length of 20 μm and a channel width of 100 μm. The electrode film thickness was made to be 100 nm after sintering.
(4) Sintering of electrode The source electrode and the drain electrode were obtained by sintering the support body in which the source electrode and the drain electrode pattern were formed at 180 degreeC for 30 minute (s) with a thermostat and dryer. The number of rotations during spin coating was adjusted so that the thickness of the sintered film was 100 nm.
(5) Surface treatment of electrode A support on which a gate electrode, an insulating film, a source electrode and a drain electrode were formed was immersed in an isopropyl alcohol solution of 30 mmol / L pentafluorobenzenethiol for 20 minutes. Immediately after immersion, the substrate was washed with isopropyl alcohol.
(6) Formation of semiconductor layer An organic semiconductor was used as the semiconductor for producing the TFT element. As the organic semiconductor used in this experiment, a p-xylene solution of 0.4 wt% C10-BTBT-yne-PhC5 was used. The TFT element was produced by drop casting the organic semiconductor solution to the channel portion between the source electrode and the drain electrode. After drop casting the semiconductor solution, the solvent p-xylene was evaporated at room temperature.
(7) Evaluation of TFT characteristics The fabricated element was subjected to heat treatment in the atmosphere at 80 ° C. for about 10 minutes, and then measured for Id-Vg and Id-Vd characteristics using a semiconductor parameter measuring device (Keithley 4200). The field effect mobility and the ON / OFF ratio were determined by a known method. The unit of field effect mobility is cm2 / Vs.

Table 2 shows the characteristics of the TFT fabricated according to Example 3. In the sintering method using flash light of the present invention, the nano silver particles of the electrode were sintered and bulked, and no coarse particles were observed. A TFT element using a smooth silver electrode formed by bulking the nanosilver particles exhibits extremely good TFT characteristics. The field effect mobility of the TFT at this time was 0.46 cm ² / Vs.

On the other hand, the TFT manufactured by Comparative Example 3 and the field effect mobility showed a very low value of 0.001 cm ² / Vs. In the electrode produced by thermal sintering, in addition to being not bulked, coarse particles having a particle diameter of about 100 nm to 200 nm were observed.

  Table 1 shows the surface resistance and volume resistivity comparison of the sintered films obtained when flash photosintering (Example 1) or 180 ° C. heat (Comparative Example 1) at each irradiation distance (energy density). It is.

  The lower part of Table 1 shows a comparison of the surface resistance and volume resistivity of the sintered films obtained when flash photosintering (Example 2) or heat at 180 ° C. (Comparative Example 2) at each irradiation distance (energy density). It is.

Table 2 shows the characteristics of the thin film transistors produced using the electrodes obtained by sintering the source electrode and drain electrode patterns produced by letterpress reverse printing by heat at 180 ° C. (Comparative Example 3) or flash light irradiation (Example 3).

Claims (4)

A paste containing metal nanoparticles is applied to the surface of the substrate to form a coating film, and flash light irradiation with a single irradiation time of flash light irradiation of 10 ms or less and an energy density applied to the coating film of 1.9 J / cm ² or more The manufacturing method of the metal nanoparticle sintered film sintered by this. 2. The method for producing a sintered metal nanoparticle according to claim 1, wherein the metal nanoparticle has an average particle size of 1 μm or less and includes particles made of a metal selected from the group consisting of gold, silver, and copper. The coating film is formed by spin coating, bar coating, slot die coating, blade coating, painting, dip pen, syringe, air brush, lithography, screen printing, inkjet printing, gravure printing, gravure offset printing, letterpress reverse printing, laser printing. The method for producing a sintered metal nanoparticle film according to claim 1 or 2, selected from the group consisting of: xerographic printing, pad printing, and combinations thereof. The manufacturing method of the semiconductor element, thin-film transistor, and electronic device containing the preparation methods of the metal nanoparticle sintered film of any one of Claims 1-3.

Images