KR20120101900A - Organic thin film transistor manufacturing method of organic thin film transistor, otft manufactured by the method, display element manufactured by the otft, and display device manufactured by the display element - Google Patents

Abstract

PURPOSE: A method for manufacturing an organic thin film transistor, the organic thin film transistor manufactured by the same, a display device including the organic thin film transistor, and an electronic device including the display device are provided to reduce a contact resistance between an organic semiconductor layer and electrodes by differently forming surface properties of a source electrode and a drain electrode. CONSTITUTION: A gate electrode(12) is formed on a substrate(11). A gate insulation layer(13) is formed on the gate electrode. A source electrode(15A) and a drain electrode(15B) are formed on the gate insulation layer. The surface properties of the source electrode and the drain electrode are asymmetrical by a surface property process. An organic semiconductor layer(17) is formed on the source electrode and the drain electrode.

Description

FIELD OF THE INVENTION Organic Thin Film Transistor manufacturing Method of Organic Thin Film Transistor, OTFT manufactured by the Method, Display element manufactured by the OTFT, and Display Device manufactured by the Display element}

The present invention relates to a technology for manufacturing an organic thin film transistor, and more particularly, the surface characteristics of the source electrode and the drain electrode are differently formed, thereby reducing contact resistance between the organic semiconductor layer and the electrodes and growing the organic semiconductor layer. The present invention relates to a method for manufacturing an organic thin film transistor capable of improving the device characteristics by supporting the formation thereof according to the intention of manufacturing, a thin film transistor manufactured by the same, a display device including the same, and a display electronic device formed of the display device. .

In electronic devices such as integrated circuits and liquid crystal display devices, an electrode formation pattern to be formed on a substrate is becoming more and more miniaturized due to the increase in the degree of integration thereof and the miniaturization of the device. In order to form a fine pattern of an electrode on such a substrate, a shadow mask, photolithography or ink-jet printing is used. As described above, a so-called active matrix drive type liquid crystal display panel constituted by a thin film transistor (hereinafter also referred to as "TFT") on a glass substrate is mainly exposed to light using a photo mask, similar to the manufacturing technology of a semiconductor integrated circuit. It has been produced by patterning a variety of thin films by the process. That is, the production technology which efficiently performs the mass production which obtains several liquid crystal display panels from one mother glass substrate, has been employ | adopted. And the size of the mother glass substrate used for manufacturing a display panel has gradually enlarged. As a result, production techniques have been advanced to obtain a plurality of display panels from a single substrate.

On the other hand, when the size of a glass substrate or a display panel was small, it was possible to patterning process relatively simply by the exposure apparatus, but it became impossible to simultaneously process the whole surface of a display panel by one exposure process as board | substrate size enlarged. In order to solve this problem, methods have been developed in which a photoresist-coated region is divided into a plurality of blocks, and the exposure process is repeatedly performed on a block-by-block basis for the entire surface of the substrate. However, such a method also has problems such as increasing the complexity of the process, has been proposed a substrate manufacturing method using the inkjet method. In other words, the droplet ejection technique has been used for printing text and images, but has been applied in the semiconductor field to solve the above problems. For example, it has been developed by a method of discharging a droplet onto a predetermined region, that is, a method of forming a film pattern such as conductive film wiring by the inkjet method. The thin film transistor formed in the above-described various manners includes three electrodes, an insulating layer and a semiconductor layer. The electrode layer, the insulating layer, and the semiconductor layer forming method of the device include a wet process such as a printing method and a dry process such as vacuum deposition or sputtering. However, a wet process may be applied in consideration of cost reduction.

On the other hand, conventionally, the surface of the gate insulating layer is treated with a surface treatment agent represented by a silane coupling agent for the purpose of improving the crystallinity of the organic semiconductor layer constituting the channel formation region as a method for improving the performance of the organic thin film transistor, A method of forming a channel region using an organic semiconductor material has been proposed thereon. However, the conventional method has a problem of increasing the liquid repellency of the insulating film surface by the ideal surface treatment to completely cover the substrate surface with a silane coupling agent without gaps. Accordingly, there is a need for a new method for improving the electrical characteristics of the thin film transistor in the electrode formation process and the organic semiconductor layer formation process.

Therefore, in order to solve the above problems, the present invention provides a method of manufacturing an organic thin film transistor that supports the improvement of crystal orientation when forming an organic semiconductor layer by forming asymmetrical surface characteristics of the source electrode and the drain electrode, thereby The present invention provides a manufactured thin film transistor, a display device including the same, and a display electronic device formed of the display device.

In order to achieve the above object, the present invention is a process of forming a gate electrode on a substrate, a process of forming a gate insulating film on the gate electrode, disposed face to face at a predetermined interval consisting of a channel on the gate insulating film Forming a source electrode and a drain electrode, forming a surface property of the source electrode and the drain electrode asymmetrically, forming a organic semiconductor layer on the source electrode and the drain electrode having the asymmetric surface property Disclosed is a configuration of an organic thin film transistor manufacturing method comprising a.

The surface characteristic processing may be a process of forming a characteristic layer for differently configuring surface characteristics on at least one surface of the source electrode and the drain electrode. Forming a first characteristic layer on the source electrode, maintaining a surface state of the source electrode and forming a second characteristic layer on the drain electrode, forming a first characteristic layer on the source electrode, and It may include any one of the process of forming a second characteristic layer on the drain electrode.

The first characteristic layer and the second characteristic layer may be formed of different materials, may be formed of a different material from the source electrode and the drain electrode, and may be formed by being dried after being coated by an inkjet method. have.

The forming of the feature layer may include forming a feature layer having a first thickness on a source electrode or a drain electrode, and forming a feature layer having a same material as the feature layer having a first thickness but having a different thickness. The method may include forming a drain electrode or a source electrode. In this case, the forming of the source electrode and the drain electrode may be asymmetric such that the thicknesses of the source electrode and the drain electrode have the same height even after the formation of the characteristic layers. It can be a process of forming.

Meanwhile, the forming of the organic semiconductor layer may be a process of applying the organic semiconductor layer material by an inkjet method and applying the organic semiconductor material generated by any one or a combination of organic materials, inorganic materials, and oxides, wherein the organic semiconductor layer material is formed. The organic material may be a material in which crystals are grown in a predetermined direction by self-aggregation during drying. In addition, the method may further include applying heat to a substrate during the organic semiconductor drop coating while forming the organic semiconductor layer.

In addition, the present invention may include an organic thin film transistor including an organic semiconductor layer formed through the above-described process, a display device manufactured based on the organic thin film transistor, and a display electronic device including the display device.

According to the present invention having the above-described configuration, the present invention can produce a device having better electrical characteristics by inducing crystal growth of the organic semiconductor layer to be formed according to the manufacturer's intention by different surface characteristics of the electrode To help.

1 is a cross-sectional view showing a cross section of an organic thin film transistor according to a first embodiment of the present invention.
2 is a cross-sectional view illustrating a cross section of an organic thin film transistor according to a second exemplary embodiment of the present invention.
FIG. 3 is a view for explaining fabrication of the organic thin film transistor shown in FIGS. 1 and 2.
4 is a flowchart illustrating a method of manufacturing a thin film transistor according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, only parts necessary for understanding the operation according to the embodiment of the present invention will be described, it should be noted that the description of other parts will be omitted so as not to distract from the gist of the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary meanings and the inventor is not limited to the meaning of the terms in order to describe his invention in the best way. It should be interpreted as meaning and concept consistent with the technical idea of the present invention. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention, and not all of the technical ideas of the present invention are described. Therefore, It is to be understood that equivalents and modifications are possible.

1 is a schematic cross-sectional view of an organic thin film transistor 100 for explaining the structure of the organic thin film transistor 100 according to the first embodiment of the present invention.

Referring to FIG. 1, the organic thin film transistor 100 of the present invention includes a gate electrode 12 formed on the substrate 11 and a gate insulating layer 13 formed on the substrate 11 including the gate electrode 12. A source electrode 15A and a drain electrode 15B arranged on both sides of the gate electrode 12 on the gate insulating layer 13, a first characteristic layer 21A formed on the source electrode 15A, and the drain electrode 15B. A second characteristic layer 21B formed on the second insulating layer 21B, a first characteristic layer 21A corresponding to the gate electrode 12 on the gate insulating layer 13, and formed on the source electrode 15A and the drain electrodes 15B; The organic semiconductor layer 17 is formed to be in contact with the second characteristic layer 21B. Here, the source electrode 15A and the drain electrode 15B formed on the gate insulating layer 13 are spaced apart from each other by a predetermined interval so that a channel having a predetermined width and length is formed between the source electrode 15A and the drain electrode 15B. Can be formed.

The organic thin film transistor 100 of the present invention having such a structure is formed by coating the first characteristic layer 21A and the second characteristic layer 21B with different materials, and as a result, the source electrode 15A and the drain electrode ( 15B) to help shape the surface properties differently. Accordingly, the organic semiconductor layer 17 formed on the first characteristic layer 21A and the second characteristic layer 21B has an organic semiconductor coated on the source electrode 15A and the drain electrode 15B having different surface properties. While the crystal is grown while performing the self-aggregation, it can grow into a crystal having a certain orientation depending on the influence of the surface properties of the asymmetric electrodes. Hereinafter, each component of the organic thin film transistor 100 of the present invention will be described in detail.

The substrate 11 may be formed using a material having insulating properties such as glass, silicon (Si), a plastic material, and the like. In particular, when the organic thin film transistor 100 is applied to a flexible device, the substrate 11 is preferably formed of a plastic material having flexibility. In this case, as the plastic material, polycarbonate (PC), polymethyl methacrylate (PolyMethylMetaAcrlate, PMMA), polydimethylsiloxane (PolyDiMethylSiloxane, PDMS), polyetherimide (Polyetherimide, PEI), polyetheretherketone (polyetheretherketone) , PEEK), polyimide (PI), polyethersulfone (PES), polyetherimide (PEI), polyester (Polyester, PET), polyethylenenaphthalate (PEN) and cyclic olefins Any one selected from the group consisting of cyclic Olefin Copolymer (COC) may be applied.

The gate electrode 12 may include a metal material or a metal compound material. Metal materials applied to the gate electrode 12 include gold (Au), silver (Ag), platinum (Pt), chromium (Cr), titanium (Ti), copper (Cu), aluminum (Al), and tantalum (Ta). ), Molybdenum (Mo), tungsten (W), nickel (Ni) or palladium (Pd). The metal compound that may be applied to the gate electrode 12 may be indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), al doped zinc oxide (AZO), or gallium zinc oxide (GZO). This may include.

The gate insulating layer 13 may include an inorganic insulating material or an organic insulating material. Here, the inorganic insulating material that may be applied to the gate insulating layer 13 may include silicon oxide (SiO 2), and specifically, siloxane or silozne, which may form silicon oxide through a solution process. And spin on glass (SOD) including spin on glass (SOG) or polysilazane (polysilazane) including any one selected from the group consisting of silicates. The organic insulating material that may be applied to the gate insulating layer 13 may include parylene, epoxy, polyimide (PI), polyamide (PA), polyvinyl chloride, PVC), benzocyclobutene (BCB), polyvinyl alcohol (polyvinyl alcohol, PVA) polyvinylphenol (polyvinylphenol, PVP) or cyclopentene (cyclopentene, CyPe) may be included.

The source electrode 15A and the drain electrode 15B may be formed of a metal material or a metal compound, for example, gold (Au), silver (Ag), platinum (Pt), chromium (Cr), titanium (Ti), or copper. (Cu), aluminum (Al), tantalum (Ta), molybdenum (Mo), tungsten (W), nickel (Ni) or palladium (Pd), indium tin oxide (ITO), indium zinc oxide (IZO), Indium Tin Zinc Oxide (ITZO), Al doped Zinc Oxide (AZO), or Gallium Zinc Oxide (GZO) may be included. However, the source electrode 15A and the drain electrode 15B of the present invention may be solution-processed, thereby performing inkjet printing. PEDOT / PSS (poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) may be used, which may be applied to PEDOT / PSS, and a leveling agent may be added when forming electrodes using the PEDOT / PSS.

The first characteristic layer 21A is formed on the source electrode 15A to change the surface characteristics of the source electrode 15A. The first characteristic layer 21A is formed of a metal material of a conductor similar to that of the source electrode 15A, but is composed of a material different from the material forming the source electrode 15A to change the surface characteristics of the source electrode 15A. Or may be composed of a substance with additional solvent. The first characteristic layer 21A has a thickness smaller than the thickness of the source electrode 15A and may be formed by an inkjet method.

The second characteristic layer 21B is formed on the drain electrode 15B to change the surface characteristics of the drain electrode 15B. The second characteristic layer 21B may be formed of a metal material of a conductor similar to that of the drain electrode 15B, and may be formed of a material and a kind of forming the drain electrode 15B to change the surface characteristics of the drain electrode 15B. It may be composed of other materials or materials with added solvent. In addition, the second characteristic layer 21B may be formed of a material different from that of the first characteristic layer 21A, thereby supporting surface characteristics of the source electrode 15A and the drain electrode 15B different from each other. Similar to the first characteristic layer 21A, the second characteristic layer 21B has a thickness smaller than that of the drain electrode 15B and may be formed by an inkjet method.

The first and second characteristic layers 21A and 21B may be selected from materials other than those employed for forming electrodes, among the materials described in the source and drain electrodes 15A and 15B, respectively. have.

The organic semiconductor layer 17 serves as a movement path of carriers such as holes or electrons, and may include an organic material. The organic semiconductor layer 17 is formed to cover at least a portion of the source electrode 15A and the drain electrode 15B on which the first and second characteristic layers 21A and 21B are formed. Organic materials that may be applied to form the organic semiconductor layer 17 include pentacene, pentacene, triisopropylsilylethynyl-pentacene, tetracene, anthracene, naphthalene, naphthalene, and alpha. -6-thiophene, alpha-4-thiophene, perylene and its derivatives, rubrene and its derivatives, coronene and its derivatives, perylenetetracarboxylic diimide diimide) and its derivatives, perylene tetracarboxylicdianhydride and its derivatives, polythiophene and its derivatives, polyparaphenylenevinylene and its derivatives, polyparaphenylene and its derivatives, polyple Lauren and its derivatives, polythiophenevinylene and its derivatives, polythiophene-heterocyclic aromatic copolymers and their derivatives, oligoacenes and derivatives thereof of naphthalene, oligothiophenes of alpha-5-thiophene and these Derivative, it can be used for various materials such as phthalocyanine and derivatives thereof, pie that does not contain or contains a metal pyromellitic dianhydride and a derivative thereof, a pie pyromellitic diimide ticks and derivatives thereof. However, the present invention is not limited thereto, and various materials may be selected according to the purpose of use and required characteristics of the organic thin film transistor 100.

In particular, the organic semiconductor layer 17 of the present invention may be formed by dropping an organic semiconductor drop on the source electrode 15A and the drain electrode 15B by an inkjet method. The dropped organic semiconductor drop may grow with crystals in a predetermined direction during the drying process. In particular, since the organic semiconductor drop of the present invention is formed on the first characteristic layer 21A and the second characteristic layer 21B made of different materials, the surface characteristics of the organic semiconductor drop are uniform on the source electrode 15A and the drain electrode 15B having different surface characteristics. It is aromatic and can be grown into crystals. As a result, in the organic semiconductor layer 17 of the present invention, the crystal direction is induced according to different surface characteristics of the source electrode 15A and the drain electrode 15B, so that the transistors are electrically connected between the source electrode 15A and the drain electrode 15B. It can be prepared in a form that improves properties. In particular, the organic semiconductor drop is applied to the first characteristic layer 21A and the second characteristic layer 21B having different surface properties, so that the organic semiconductor layer 17 has a different energy barrier on the surface of each electrode. The contact resistance of the source electrode 15A and the drain electrode 15B may be reduced. The organic thin film transistor 100 of the present invention manufactured in this manner can easily adjust the work-function barrier property according to the formation control of the first characteristic layer 21A and the second characteristic layer 21B. There will be. Here, the work function may mean the minimum work or energy required to bring out one electron in the material.

As described above, the organic thin film transistor 100 according to the exemplary embodiment of the present invention has an asymmetrical surface property of the source electrode 15A and the drain electrode 15B, thereby forming an image on the source electrode 15A and the drain electrode 15B. It is possible to reduce contact resistance of the organic semiconductor layer 17 formed on the substrate and to control crystal growth of the organic semiconductor layer 17 according to the manufacturer's intention.

2 is a view for explaining the shape of the organic thin film transistor 100 according to the second embodiment of the present invention. Prior to the description, in the case of the organic thin film transistor 100 according to the second embodiment of the present invention, only the configuration of the characteristic layer is different from that of FIG. 1, and the other configurations have the same shape and material as those described in FIG. Can be formed. Accordingly, in the following description, detailed descriptions of the substrate 11, the gate insulating layer 13, the source electrode 15A, the drain electrode 15B, and the like will be omitted.

Referring to FIG. 2, in the organic thin film transistor 100 of the present invention, a gate electrode 12 is provided on a substrate 11, and a gate insulating layer 13 covering the substrate 11 and the gate electrode 12 is provided. ). In addition, a source electrode 15A and a drain electrode 15B aligned with the gate electrode 12 may be provided on the gate insulating layer 13.

In particular, in the organic thin film transistor 100 according to the second embodiment of the present invention, a characteristic layer 23A having a first thickness is formed on the source electrode 15A, and the characteristic layer having a second thickness is formed on the drain electrode 15B. 23B) can be formed. Here, the first thickness characteristic layer 23A and the second thickness characteristic layer 23B may be formed on the source electrode 15A and the drain electrode 15B by an inkjet method. In addition, the first thickness characteristic layer 23A may have a relatively larger thickness than the second thickness characteristic layer 23B, and the two characteristic layers may be formed of the same material. However, in order for the first thickness characteristic layer 23A to have a larger thickness than the second thickness characteristic layer 23B, an additional material dropping process may be required in the inkjet method application process. Alternatively, it may be designed such that the amount of injection of the liquid phase through the nozzle or the injection hole of the nozzle forming the characteristic layer 23A of the first thickness is greater than the amount of material for the characteristic layer 23B of the second thickness. On the other hand, when it is necessary to keep the entire thickness of the source electrode 15A on which the characteristic layer 23A of the first thickness is formed and the entire thickness of the drain electrode 15B on which the characteristic layer 23B of the second thickness is formed equal, The thicknesses of the electrode 15A and the drain electrode 15B may be differentially formed to make the overall thickness the same after the formation of the characteristic layers. As described above, the organic thin film transistor 100 according to the exemplary embodiment of the present invention controls the thicknesses of the characteristic layers formed on the source electrode 15A and the drain electrode 15B, and as a result, changes the surface characteristics of each electrode. The crystal direction of the organic semiconductor layer 17 may be adjusted according to the manufacturer's intention.

Meanwhile, in the above description, the first characteristic layer 21A and the second characteristic layer 21B are formed on the source electrode 15A and the drain electrode 15B, respectively, but the present invention is not limited thereto. That is, in the organic thin film transistor 100 of the present invention, only at least one characteristic layer of the first characteristic layer 21A and the second characteristic layer 21B may be formed on the corresponding electrode. In more detail, the organic thin film transistor 100 of the present invention is configured to configure the surface characteristics of the source electrode 15A and the surface characteristics of the drain electrode 15B differently, and are only formed on the source electrode 15A. The first characteristic layer 21A may be formed, and the second characteristic layer 21B may not be formed on the drain electrode 15B. In the opposite case, that is, only the second characteristic layer 21B may be formed on the drain electrode 15B. Accordingly, the source electrode 15A and the drain electrode 15B of the present invention may be configured to have different surface characteristics. In addition, as described above with respect to the first thickness characteristic layer 23A and the second thickness characteristic layer 23B, the organic thin film transistor 100 of the present invention may be connected to either the source electrode 15A or the drain electrode 15B. It may be made to form only.

3 is a view for explaining an example of a manufacturing process for forming a characteristic layer of the organic thin film transistor 100 according to an embodiment of the present invention.

Referring to FIG. 3, in the organic thin film transistor 100 of the present invention, after the source electrode 15A and the drain electrode 15B are formed on the gate insulating layer 13, the first characteristic layer 21A based on the inkjet method. ) And the second characteristic layer 21B. In this case, the organic thin film transistor 100 of the present invention is formed by applying a drop onto the source electrode 15A and the drain electrode 15B through the nozzle 103.

Referring to the drawings, the first characteristic layer drop 104 is dropped onto the source electrode 15A through the injection hole of the nozzle 103 provided on the left side, and the second characteristic layer through the injection hole of the nozzle 103 provided on the right side. Drop 105 is dropped on drain electrode 15B. In this case, the first characteristic layer drop 104 and the second characteristic layer drop 105 may be made of different materials. In addition, the first characteristic layer drop 104 and the second characteristic layer drop 105 may have a different injection amount discharged to each electrode through the injection hole of the nozzle 103. The first characteristic layer drop 104 is dropped onto the source electrode 15A and then dried to convert to the first characteristic layer 21A which changes the surface characteristics of the source electrode 15A. The second characteristic layer drop 105 may be dropped onto the drain electrode 15B and then dried to be converted to the second characteristic layer 21B which changes the surface characteristics of the drain electrode 15B.

As described above, the organic thin film transistor 100 of the present invention forms a characteristic layer by dropping a material capable of forming the characteristic layer on the source electrode 15A and the drain electrode 15B as a drop. In this case, the organic thin film transistor 100 of the present invention may form the characteristic layers having different characteristics by dividing the source electrode 15A and the drain electrode 15B, respectively. Accordingly, when the organic semiconductor layer 17 is formed on the source electrode 15A and the drain electrode 15B having an asymmetric surface property, crystal growth of the organic semiconductor layer 17 may be induced in a predetermined direction. .

In the above, the shape of the characteristic layer in the structure of the organic thin film transistor 100 according to the exemplary embodiment of the present invention has been exemplarily described. Hereinafter, a method of manufacturing the organic thin film transistor 100 of the present invention will be described in detail with reference to the accompanying drawings.

4 is a view for explaining a method of manufacturing an organic thin film transistor having a characteristic layer according to an exemplary embodiment of the present invention.

Referring to FIG. 4, in the organic thin film transistor 100 of the present invention, a process of forming a gate electrode 12 on a substrate 11 [S101], and on the substrate 11 and the gate electrode 12. Forming a gate insulating film 13 [S103], forming a source electrode 15A and a drain electrode 15B on the gate insulating film 13 [S105], a surface of the source electrode and a surface of the drain electrode Forming at least one characteristic layer to have different characteristics [S107], and forming the organic semiconductor layer 17 on the source electrode 15A and the drain electrode 15B on which the characteristic layer is formed [S109]. ] Is included.

In more detail, in the method of forming the electrode and the organic semiconductor layer of the organic thin film transistor of the present invention, the substrate 11 is prepared, and the gate electrode 12 is formed on the substrate 11 prepared as in step S101. The process of forming the gate electrode 12 may be performed by, for example, cleaning the substrate 11 to remove impurities, and evaporating deposition and patterning processes. In this case, the substrate 11 may be made of glass, silicon, plastic, or the like, but the present invention is not limited thereto. When the substrate 11 is formed of a plastic material, the substrate 11 is a polycarbon ester (PC), polymethyl methacrylate (PMMA), polyethylene naphthalate (PEN) as described above ), Polydimethylsiloxane (PDMS), polyetherimide (PEI), polyetheretherketone (PEEK), polyimide (PI), polyethersulfone (PES), polyetherimide Any one selected from the group consisting of (Polyetherimide, PEI), polyester (Polyester, PET) and cyclic olefin copolymer (Cyclic Olefin Copolymer, COC) can be applied.

Meanwhile, the gate electrode 12 may be made of a conductive material or a metal. For example, the gate electrode 12 may include gold (Au), silver (Ag), aluminum (Al), nickel (Ni), molybdenum (Mo), tungsten (W), indium tin oxide (ITO), and polythiophene. It may be formed of (polythiophene), polyaniline (polyaniline), polyacetylene (polyacetylene), polypyrole (polypyrole), polyphenylene vinylene (polyphenylene vinylene), PEDOT (polyethylenedioxythiophene) / PSS (polystyrenesulfonate) mixture. The gate electrode 12 may be formed using various known methods. When the substrate 11 is formed of a plastic material, the gate electrode 12 may be formed at a low temperature (250 ° C. or lower) and in air. 12) It is preferable to form using a solution process capable of forming. In this case, the solution process may be spin coating, slit coating, drop casting, dip casting, ink jet, printing, or the like. And any method selected from the group consisting of imprint can be applied.

Next, in step S103, a gate insulating layer 13 covering the gate electrode 12 is formed. In the formation of the gate insulating film 13, when the gate electrode 12 is formed on the substrate 11, the gate insulating film 13 is formed on the substrate 11 by a specific method such as vacuum deposition or a solution process. In this case, in the process of forming the gate insulating layer 13, the material used as the gate insulating layer 13 may be formed using an organic insulating material or an inorganic insulating material. Here, the organic insulating material is parylene, epoxy, polyimide (PI), polyamide (PA), polyvinyl chloride (PVC), benzocyclobutene (BCB) ), Polyvinyl alcohol (polyvinylalcohol, PVA), polyvinylphenol (polyvinylphenol, PVP) or cyclopentene (cyclopentene, CyPe) and the like. The inorganic insulating material is silicon oxide (SiO 2), specifically, SOG including any one selected from the group consisting of siloxane, silazne, and silicate, which can form silicon oxide through a solution process. (Spin On Glass) or SOD (Spin On Dielectric) including polysilazane (polysilazane) may be included. The gate insulating layer 13 is preferably formed using an inorganic insulating material having excellent mechanical and chemical stability compared to the organic insulating material, among which, the gate insulating layer 13 is inexpensive and can be easily formed using a solution process. SOG excellent in roughness) and chemical stability can be employed. However, the material for forming the gate insulating layer 13 of the present invention is not limited to the above examples, and various materials capable of insulating the gate electrode 12 may be used as the material for forming the gate insulating layer 13. There will be. The thickness of the gate insulating layer 13 may be appropriately adjusted as necessary. The solution process of the method for forming the gate insulating film 13 is, for example, any one method selected from the group consisting of spin coating method, slit coating method, drop casting method, deep casting method, inkjet method, printing method and imprint method Can be applied.

Next, the source electrode 15A and the drain electrode 15B are formed in step S105. When the source / drain electrodes are formed, the source electrode 15A and the drain electrode 15B may be formed on the gate insulating layer 13 so as to have a predetermined area at both sides with respect to a predetermined interval, that is, the channel 14. In order to form the source electrode 15A and the drain electrode 15B, an intaglio region having a predetermined depth is formed in the gate insulating layer 13 with respect to the channel 14 region, and the source electrode 15A is formed in the intaglio region. And drain electrode 15B may be provided. The source / drain electrode is a conductive material, and a material selected from the group that can be used in the form of ink, for example, polythiophene, polyaniline, polyacetylene, polypyrrole, polyphenyl Gold (Au), silver (Ag), aluminum (Al), nickel (Ni), molybdenum (Mo), tungsten (W) as well as polyphenylene vinylene (PE) and polyethylenedioxythiophene / PEDOT (polystyrenesulfonate) ), Indium tin oxide (ITO), indium zinc oxide (IZO) and the like, but may be formed of a metal oxide or the like, but is not limited thereto.

Next, in step S107, the characteristic layer may be formed in at least one place such that the surface characteristics of the source electrode 15A and the drain electrode 15B have different characteristics. In other words, the first characteristic layer 21A is formed on the source electrode 15A, and the drain electrode 15B does not have a separate characteristic layer, so that the surface of the source electrode 15A and the surface of the drain electrode 15B are formed. The property can be controlled to be asymmetric. Here, since the first characteristic layer 21A is formed on the source electrode 15A, the thickness of the source electrode 15A side may be higher than that of the drain electrode 15B. Accordingly, when the height of the source electrode 15A side and the drain electrode 15B side need to be kept constant, the drain electrode 15B may be formed in consideration of the height of the first characteristic layer 21A when the source electrode 15A is formed. It can be formed to have a relatively small thickness in comparison. In the above description, the formation of the first characteristic layer 21A on the source electrode 15A has been described. However, the organic thin film transistor 100 of the present invention does not provide a separate characteristic layer on the source electrode 15A. The characteristic layer may be formed on the drain electrode 15B.

In addition, a first characteristic layer 21A is formed on the source electrode 15A by using a first material, and a second characteristic layer 21B is formed on the drain electrode 15B by using a second material that is different from the first material. ) Can be formed. Accordingly, the source electrode 15A and the drain electrode 15B of the present invention have asymmetrical surface characteristics due to the characteristic layers having different characteristics. The first characteristic layer 21A and the second characteristic layer 21B may be formed by being discharged on the source electrode 15A and the drain electrode 15B through different nozzles based on the inkjet method, respectively.

When the thicknesses of the source electrode 15A and the drain electrode 15B are not considered, the first and second characteristic layers 21A and 21B may be formed of the same material having different thicknesses. In this case, the organic thin film transistor 100 of the present invention discharges a larger amount of material to a specific characteristic layer among the first characteristic layer 21A and the second characteristic layer 21B based on the inkjet method, thereby increasing the thickness relatively. Can be formed.

In the above description, a material different from that of the source electrode 15A and the drain electrode 15B may be applied to the first and second characteristic layers 21A and 21B. That is, the first characteristic layer 21A and the second characteristic layer 21B are conductive materials, except for materials used in the source electrode 15A and the drain electrode 15B. It may be the material of choice.

Next, in step S109, the organic semiconductor layer 17 is formed on the electrodes on which the at least one characteristic layer is formed. The organic semiconductor layer 17 acts as a passage through which carriers such as holes or electrons move, and may be formed of an organic material using a solution process. That is, the organic semiconductor layer 17 may be formed by applying a liquid phase composed of an organic semiconductor material on a substrate on which the source electrode and the drain electrode are formed. Organic materials usable as the organic semiconductor layer 17 include pentacene (pentacene), tips-pentacene (6,13-bis (triisopropylsilylethynyl) pentacene, TIPS-pentacene), tetracene (tetracene), anthracene (anthracene) , Naphthalene, alpha-6-thiophene, alpha-4-thiophene, perylene and its derivatives, rubrene and its derivatives, coronene and its derivatives, perylenetetra Carboxylic diimide and its derivatives, perylene tetracarboxylic hydride and its derivatives, polythiophene and its derivatives, polyparaphenylenevinylene and its derivatives, polyparaphenyl Lene and derivatives thereof, polyfluorene and derivatives thereof, polythiophenevinylene and derivatives thereof, polythiophene-heterocyclic aromatic copolymers and derivatives thereof, oligoacenes and derivatives thereof of naphthalene, alpha-5-thiophene Oligothiophene Derivatives thereof, phthalocyanines with or without metals and derivatives thereof, pyromellitic dianhydrides and derivatives thereof, pyromellitic diimides and derivatives thereof, copper pthalaocyanine, polyaniline , Polyacetylene, polypyrrole, polyphenylenevinylene, and derivatives thereof may be used, and may be selected according to the purpose and required properties of the organic thin film transistor.

In particular, since the organic semiconductor layer 17 of the present invention is formed on at least one of the source electrode 15A and the drain electrode 15B on which the characteristic layer is formed, the organic semiconductor layer 17 is dried after application of the organic semiconductor drop and is affected by the characteristic layer. Crystals may be grown in a predetermined direction, for example, in a direction connecting the source electrode 15A and the drain electrode 15B. In this process, since the surface energy state of the electrodes is provided asymmetrically, the organic semiconductor layer 17 may also be asymmetrically dried during drying. As a result, the crystal of the organic semiconductor layer 17 may be induced to grow in the direction of the source electrode 15A to the drain electrode 15B or in the direction of the drain electrode 15B in the direction of the source electrode 15A. Improvement can be achieved. When manufacturing the organic thin film transistor 100 of the present invention, heat may be applied to the substrate 11 to improve crystal growth direction during the formation of the organic semiconductor layer 17. Meanwhile, various printing methods such as a drop casting, a dispensing process, a gravure offset, and a reverse offset may be applied as the method of forming the organic semiconductor layer 17 as well as the inkjet method.

In addition, in the organic thin film transistor of the present invention, a method of forming each functional layer except for the characteristic layer and the organic semiconductor layer is not particularly limited, and at least one method of a dry process or a wet process may be applied. For example, the formation of the gate insulating film 13 may be performed by a wet process method such as sputtering, vapor deposition, ion plating, photolithography, etching, or a printing method. As the wet process, for example, inkjet method, screen printing method, spin coating method, bar coating method, slit coating method, dip coating method, spray coating method, gravure printing method, flexographic printing method, gravure offset method, convex plate offset method , Convex reversal printing, or the like is used.

When the printing method is applied, the insulating ink for forming the gate insulating film 13 may contain a material exhibiting insulating properties. The insulating ink may be, for example, an epoxy resin, polyimide resin, polyvinylpyrrolidone resin, polyvinyl alcohol resin, acrylonitrile resin, methacryl resin, polyamide resin, polyvinylphenol resin, phenol resin, Polyamide-imide resin, fluororesin, melamine resin, urethane resin, polyester resin, alkyd resin and the like can be applied. In addition, the insulating ink may be used alone or in combination of two or more kinds of the above-described materials, and if necessary, components such as high dielectric constant particles such as alumina fine particles, silica fine particles and tantalum oxide fine particles, and low dielectric constant particles such as hollow silica fine particles. This may be added. There is no limitation on the solvent applicable to the insulating ink, and various organic solvents such as water, hydrocarbon, alcohol, ketone, ether, ester, glycol ether and fluorine may be used. In addition, binder components such as resins, antioxidants, leveling agents, mold release accelerators, and various catalysts for promoting film formation may be used as solvents, and silicone-based and fluorine-based surfactants may be added as necessary. The conversion of the functional material layer constituting the transistor from the ink film layer can be performed by an optimal method for ink characteristics or electronic components, such as, for example, normal temperature drying, heat treatment, and treatment of ultraviolet rays and electron beam irradiation. .

Meanwhile, although the organic thin film transistor structure of the present invention has been described with reference to an inverted staggered type having a bottom gate type structure, the present invention is not limited thereto. That is, the method for forming the source electrode and the drain electrode having the asymmetric surface characteristics according to the present invention is a staggered type, coplanner type, inverted coplanner type organic thin film Of course, it can also be applied to the transistor structure.

The organic thin film transistor of the present invention can be applied to a display device. The aforementioned display device may be an electroluminescent device, a liquid crystal device, a particle transfer device, or the like, and may be applied to various other display devices. The display electronic device including the display device to which the organic thin film transistor of the present invention is applied may be a display device, a smart card, an inventory tag, or the like. However, the display element of the present invention is not limited to the display electronic device described above.

11: substrate
12: gate electrode
13: gate insulating film
15A: Source Electrode
15B: Drain Electrode
21A, 21B, 23A, 23B: Characteristic Layers
17: organic semiconductor layer
100: organic thin film transistor

Claims (14)

Forming a gate electrode on the substrate;
Forming a gate insulating film on the gate electrode;
Forming a source electrode and a drain electrode which are disposed to face each other at a predetermined interval configured as a channel on the gate insulating film;
A surface characteristic treatment process of asymmetrically forming surface characteristics of the source electrode and the drain electrode;
Forming an organic semiconductor layer on the source electrode and the drain electrode having the asymmetric surface property;
Organic thin film transistor manufacturing method comprising a. The method of claim 1,
The surface property treatment process
Forming a characteristic layer on the surface of at least one of the source electrode and the drain electrode; The method of claim 2,
Forming the characteristic layer is
Maintaining a surface state of the drain electrode and forming a first characteristic layer on the source electrode;
Maintaining a surface state of the source electrode and forming a second characteristic layer on the drain electrode;
Forming a first characteristic layer on the source electrode and forming a second characteristic layer on the drain electrode;
Organic thin film transistor manufacturing method comprising the process of any one of. The method of claim 3,
The first characteristic layer and the second characteristic layer
Method for manufacturing an organic thin film transistor, characterized in that formed of different materials. 5. The method according to any one of claims 3 to 4,
The first characteristic layer and the second characteristic layer
And forming a material different from that of the source electrode and the drain electrode. The method of claim 3,
The first characteristic layer and the second characteristic layer
A method of manufacturing an organic thin film transistor, which is formed by coating and drying the inkjet method. The method of claim 2,
Forming the characteristic layer is
Forming a characteristic layer having a first thickness on the source electrode or the drain electrode;
Forming a second thickness characteristic layer having the same material as the first thickness characteristic layer and having a different thickness from the drain electrode or the source electrode;
Organic thin film transistor manufacturing method comprising a. The method of claim 7, wherein
Forming the source electrode and the drain electrode
And asymmetrically forming the source electrode and the drain electrode to have the same height after the formation of the characteristic layers. The method of claim 1,
Forming the organic semiconductor layer is
A method of manufacturing an organic thin film transistor, comprising: applying an organic semiconductor layer material by an inkjet method, and applying and forming an organic semiconductor material produced by any one or a combination of organic materials, inorganic materials, and oxides. 10. The method of claim 9,
The organic material is a method of manufacturing an organic thin film transistor, characterized in that the crystal is grown in a predetermined direction according to the self-coagulation after being applied on the source electrode and the drain electrode. 10. The method of claim 9,
Applying heat to a substrate during the organic semiconductor drop coating while forming the organic semiconductor layer;
Organic thin film transistor manufacturing method comprising a further. An organic thin film transistor comprising an organic semiconductor layer formed by the method according to any one of claims 1 to 11. A display device comprising the organic thin film transistor according to claim 12. A display electronic device comprising the display element according to claim 13.

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