JP2008078281A - Organic thin film transistor manufacturing method and organic thin film transistor - Google Patents

Abstract

An organic thin film transistor that is easy to manufacture and has good characteristics and an organic thin film transistor manufactured thereby are provided.
A first member having a release layer that has a substrate and a first organic semiconductor layer and has a smaller adhesive force after heating and pressing between the substrate and the first organic semiconductor layer than the substrate, and on the substrate A first region in which an organic semiconductor layer is formed on the first surface, wherein an insulating film and a source electrode and a drain electrode are provided, and a second member having a surface having the insulating film as a first surface is prepared, or The first surface of the first organic semiconductor layer portion provided so as to be the organic semiconductor layer has a first surface smaller than the adhesive force between the release layer and the layer in contact with the release layer; Forming a self-assembled film that increases the adhesive strength with the organic semiconductor layer by heating and pressing, superimposing the first member and the second member, heating and pressing the first member and the second member, One member and the second member are separated.
[Selection] Figure 3

Description

  The present invention relates to an organic thin film transistor manufacturing method and an organic thin film transistor.

  In recent years, organic thin film transistors (OTFTs) have attracted attention as switching elements for driving pixels of next-generation low-cost flat panel display devices or electronic paper.

  The organic TFT has substantially the same structure as the silicon TFT, but there is a difference that an organic substance is used instead of silicon in the semiconductor active layer region. Since the organic TFT can be manufactured by a printing method or the like in terms of the manufacturing process, it has an advantage that it is simpler and less expensive than a silicon TFT, and is suitable for an electronic circuit board that can be bent or folded without being broken by an impact. . Taking advantage of these advantages, research for forming an organic TFT element on a flexible substrate is underway for the purpose of reducing the weight of the display panel, improving the impact resistance, displaying a curved surface, and increasing the area. In order to manufacture such a display panel at a low cost, a large process such as a vacuum process for film formation or a photolithography process for patterning is required, and a process that is costly is required. It is necessary to eliminate as much as possible.

  As an example to eliminate the costly process as much as possible, by discharging a solution in which the thin film forming material is dissolved in the solvent, the droplets of the solution are placed on the substrate and the solvent is evaporated from the droplets. In the method of forming a thin film on top, there is a thin film forming method in which a solution is discharged after processing the surface of the substrate to have a surface affinity with the thin film forming material, and the substrate has an affinity for the thin film forming material. A self-assembled film is formed as a method for treating the surface state. (See Patent Document 1).

  As a self-assembled film, there is a patterning method using a self-assembled monomolecular film (SAM: Self-Assembled Monolayer). The SAM has the property of spontaneously aligning on the substrate surface to form a monomolecular film. The SAM formed on the substrate can control water repellency and hydrophilicity. Further, since the SAM is decomposed when irradiated with ultraviolet rays, a water repellent and hydrophilic pattern can be easily formed by performing mask exposure using ultraviolet rays. By using this pattern, it is possible to create a high-definition pattern that exceeds the accuracy of the printing method.

  In addition, as a patterning method using SAM, when an organic semiconductor material is formed by OVPD (Organic Vapor Phase Deposition) after forming a SAM pattern, the organic semiconductor pattern is grown by self-selection. (See Non-Patent Document 1).

In addition, as a method for forming a device on a flexible substrate such as a plastic sheet having a low cost compared to a heat-resistant substrate such as a glass substrate or a silicon substrate, a first step of forming a release layer on a heat-resistant substrate, and a release layer A second step of forming a thin film device thereon, a third step of providing a surface layer on the opposite side of the heat resistant substrate of the thin film device, and causing a peeling phenomenon at the interface between the release layer and the heat resistant substrate. And a fourth step of peeling the heat-resistant substrate from the thin film device side. In the first step, as the release layer, due to the presence of a liquid phase at the interface with the heat-resistant substrate, the release layer A thin film that forms an organic film having a property of causing a peeling phenomenon by reducing the adhesive strength to the heat-resistant base material, and in the fourth step, causes a peeling phenomenon by interposing a liquid phase at the interface between the peeling layer and the heat-resistant substrate. Device equipment There are provided methods for producing (see Patent Document 2).
JP 2003-234522 A JP 2003-318195 A SID'04 DIGEST 45.2

  However, in the thin film forming method described in Patent Document 1, a thin film is formed by arranging droplets on a substrate. Specifically, since an ink jet method is used, a self-assembled film is used. By doing so, patterning with good shape accuracy is possible, but when a large number of organic TFTs with a large area are manufactured, there is a problem that the manufacturing time becomes long.

  In addition, when the OVPD method is used for forming the organic semiconductor film described in Non-Patent Document 1, a necessary apparatus is large and expensive.

  According to the method for manufacturing a thin film device described in Patent Document 2, at the time of transfer, by providing a portion having a partially different adhesive force at the interface between the release layer and the heat-resistant base material, The device is formed by forming the device on a glass heat resistant substrate and transferring it to another inexpensive substrate. It is described that this method makes the conditions required for the material of the final product, including the reuse of the heat-resistant substrate, moderate, and lowers the cost of the substrate without impairing the reliability. There is no description about facilitating the production of the organic semiconductor film.

  In the case of forming an organic TFT element, a source electrode, a drain electrode, a pixel electrode, a bus wiring, and the like are usually formed in advance on a substrate before the formation of an organic semiconductor film. When an organic semiconductor film is formed on these by a printing method or a vapor deposition method, there is a step or a portion with a different surface state, so that the organic semiconductor molecule arrangement is disturbed and the performance of the organic TFT element is deteriorated. Occurs.

  On the other hand, a device-forming substrate in which a uniform film of an organic semiconductor is formed on a donor substrate with good flatness to provide the formed film, and the homogeneous organic semiconductor film is provided with source / drain electrodes and the like in advance. By using the method for transferring to, a homogeneous organic semiconductor film can be formed on the device formation substrate. In this case, the organic semiconductor film is formed on the entire surface of the device formation substrate, and an organic semiconductor pattern cannot be formed. For this reason, when the organic semiconductor is formed on the entire surface of the substrate on which the device is formed, a leakage current is generated, and there is a problem that the off current of the organic semiconductor element is increased and the characteristics are not good. In addition, since the organic thin film has low chemical resistance, it is difficult to pattern by an ordinary patterning method including a photolithography process and an etching process.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method of manufacturing an organic thin film transistor element that is easy to manufacture and has good characteristics, and an organic thin film transistor manufactured thereby. is there.

  Said subject is solved by the following structures.

1. Method for manufacturing organic thin film transistor having at least source electrode, drain electrode, organic semiconductor layer connecting source electrode and drain electrode on substrate, gate electrode and organic thin film transistor having insulating film between organic semiconductor layer and gate electrode In
A first organic semiconductor layer that provides the substrate and the organic semiconductor layer; and further, between the substrate and the first organic semiconductor layer, after heating and pressing the first organic semiconductor layer from the substrate. Preparing a first member having a release layer having a low adhesive force, and a second member having a surface having an insulating film on the substrate as a first surface;
The release layer and the release layer on either the first region where the organic semiconductor layer is formed on the first surface or the surface of the portion of the first organic semiconductor layer that provides the organic semiconductor layer Self-organization that increases the adhesive force between the first surface and the first organic semiconductor layer, which is smaller even after heating and pressing than the adhesive force with the layer in contact with the layer, by heating and pressing Forming a film;
Superimposing the first member and the second member in a direction in which the first organic semiconductor layer of the first member and the first surface of the second member face each other;
Heating and pressing the first member and the second member;
The method of manufacturing an organic thin film transistor, wherein the step of separating the first member and the second member is performed in this order.

  2. 2. The method of manufacturing an organic thin film transistor according to 1, wherein the source electrode and the drain electrode are provided as uppermost layers on the first surface of the second member to be prepared.

  3. After the step of separating the first member and the second member, a step of providing the source electrode and the drain electrode connected to the organic semiconductor layer with the organic semiconductor layer formed on the second member in between. 2. The method for producing an organic thin film transistor according to 1, which is performed.

  4). The first member has a substrate, the release layer, and the first organic semiconductor layer in this order, and further between the release layer and the first organic semiconductor layer, the heating and pressing after the pressing Any one of 1 to 3, further comprising a protective layer having an adhesive force between the substrate and the release layer and an adhesive force between the first organic semiconductor layer and the release layer that is smaller than the adhesive force between the substrate and the release layer. The manufacturing method of the organic thin-film transistor as described in a term.

  5. 5. The method of manufacturing an organic thin film transistor according to any one of claims 1 to 4, wherein in the step of forming the self-assembled film, a self-assembled film is formed in the first region.

  6). The method for producing an organic thin film transistor according to any one of 1 to 5, wherein the self-assembled film is a self-assembled monomolecular film.

7). Production of an organic thin film transistor having an insulating film between at least a source electrode, a drain electrode, an organic semiconductor layer connecting the source electrode and the drain electrode, a gate electrode, and the organic semiconductor layer and the gate electrode on a substrate In the method
A first organic semiconductor layer that provides a substrate and an organic semiconductor layer that serves as the organic semiconductor layer, and further, the substrate and the first organic semiconductor layer between the substrate and the first organic semiconductor layer. A step of preparing a first member having a peeling layer having a small adhesive force after heating and pressing, and a second member having a surface having an insulating film forming the first surface on the substrate as a first surface;
In the remaining second region excluding the first region where the organic semiconductor layer is formed on the first surface, the adhesive force with the second region after heating and pressing is such that the release layer and the first region Forming a lift-off resist smaller than the adhesive strength of the organic semiconductor layer;
The surface after the lift-off resist is formed on the first surface or the surface of the first region and the first organic semiconductor layer by heating and pressing the first organic semiconductor layer. The adhesive force is made larger than the adhesive force between the release layer and the layer that is in contact with the release layer, and the adhesive force between the first organic semiconductor layer and the lift-off resist is increased on the first surface. Forming a self-assembled film larger than the adhesive force between the second region and the lift-off resist;
Superimposing the first organic semiconductor layer of the first member and the self-assembled film of the second member facing each other;
Heating and pressing the first member and the second member;
The method of manufacturing an organic thin film transistor, wherein the step of separating the first member and the second member is performed in this order.

  8). 8. The method of manufacturing an organic thin film transistor according to 7, wherein the source electrode and the drain electrode are provided as uppermost layers on the insulating film of the second member to be prepared.

  9. After the step of separating the first member and the second member, a step of providing the source electrode and the drain electrode connected to the organic semiconductor layer with the organic semiconductor layer formed on the second member in between. 8. The method for producing an organic thin film transistor according to 7, which is performed.

  10. The first member has a substrate, the release layer, and the first organic semiconductor layer in this order, and further between the release layer and the first organic semiconductor layer, the heating and pressing after the pressing Any one of 7 to 9, further comprising a protective layer having an adhesive force between the substrate and the release layer and an adhesive force between the first organic semiconductor layer and the release layer that is smaller than the adhesive force between the substrate and the release layer. The manufacturing method of the organic thin-film transistor as described in a term.

  11. 11. The method according to claim 7, wherein in the step of forming the self-assembled film, the self-assembled film is formed on a surface after the lift-off resist is formed on the first surface. Manufacturing method of organic thin film transistor.

  12 The organic material according to any one of 7 to 11, wherein the lift-off resist has a photothermal conversion function in which the adhesive force on the first surface side is reduced by irradiating light from the second member side. A method for manufacturing a thin film transistor.

  13. 13. The method of manufacturing an organic thin film transistor according to 12, wherein the light conversion function of the lift-off resist is such that gas is generated when the light is irradiated and adhesive force is reduced.

  14 The organic thin-film transistor manufactured by the manufacturing method of the organic thin-film transistor as described in any one of 1 thru | or 13.

According to the first aspect of the present invention, the first member and the second member are overlapped, and then heated and pressed to obtain the following.
(1) The adhesive force between the release layer and the first organic semiconductor layer is smaller than the adhesive force between the release layer and the substrate of the first member.
(2) The first organic semiconductor layer corresponding to the peeling layer and the layer in contact with the peeling layer when there is no self-assembled film between the first surface and the first semiconductor layer. Less than the adhesive strength. Further, when the self-assembled film is in between, the adhesive force between the first surface and the first semiconductor layer is between the release layer and the first organic semiconductor layer corresponding to the layer in contact with the release layer. Greater than adhesive strength.
(3) The self-assembled film is formed on the surface of a portion of the first organic semiconductor layer that is provided from the first region or the first organic semiconductor layer and becomes the organic semiconductor layer.

  Next, when the first member and the second member are separated, in the region where the self-assembled film is present, the peeling layer having the smallest adhesive force and the first organic semiconductor layer corresponding to the layer in contact with the peeling layer And a semiconductor layer provided separately from the first semiconductor layer is formed in the first region of the second member. Since this organic semiconductor layer was on the peeling layer of the substrate of the first member having no step and having a uniform surface state, the molecular arrangement is good and it has good characteristics. In the region where there is no self-assembled film, the first surface having the smallest adhesive force and the first semiconductor layer are separated, and the second member is in the same state as before the first member is overlaid.

  Therefore, an organic semiconductor layer having good characteristics can be formed on the second member. A source electrode and a drain electrode are provided on the first surface in advance so as to connect the organic semiconductor layers, or after the organic semiconductor layer is formed, an organic thin film transistor having good characteristics is obtained. be able to.

  Accordingly, it is possible to provide a method for manufacturing an organic thin film transistor that is easy to manufacture and has good characteristics, and an organic thin film transistor manufactured thereby.

According to the seventh aspect of the present invention, the first member and the second member are overlapped, and then heated and pressed, so that the following is obtained.
(1) The adhesive force between the release layer and the first organic semiconductor layer is smaller than the adhesive force between the release layer and the substrate of the first member.
(2) The adhesive force between the second region excluding the first region on the first surface where the organic semiconductor layer of the second member is formed and the photoresist is in contact with the release layer and the layer on the release layer. Less than the adhesive strength with the corresponding first organic semiconductor layer.
(3) There is a self-assembled film that increases the adhesive force between the surface after the lift-off resist is formed on the first surface and the first organic semiconductor layer. The first organic semiconductor in which the adhesive force between the first region where the organic semiconductor layer is formed via the self-assembled film and the first organic semiconductor layer corresponds to the release layer and the layer in contact with the release layer Greater than the adhesion to the layer. Further, the adhesive force between the first organic semiconductor layer and the lift-off resist via the self-assembled film is larger than the adhesive force between the second region of the first surface and the lift-off resist.

  Next, when the first member and the second member are separated, in the region where there is no photoresist, the peeling layer and the first semiconductor layer having the smallest adhesive force are separated and separated from the first organic semiconductor layer. The provided organic semiconductor layer is formed in the first region of the second member. Since this organic semiconductor layer was on the peeling layer of the substrate of the first member having no step and having a uniform surface state, the molecular arrangement is good and it has good characteristics. In the region where the photoresist is present, the second region of the first surface having the smallest adhesive force and the lift-off resist are separated, and the second member is in the same state as before the first member is overlaid.

  Therefore, an organic semiconductor layer having good characteristics can be formed on the second member. A source electrode and a drain electrode are provided on the first surface in advance so as to connect the organic semiconductor layers, or after the organic semiconductor layer is formed, an organic thin film transistor having good characteristics is obtained. be able to.

  Accordingly, it is possible to provide a method for manufacturing an organic thin film transistor that is easy to manufacture and has good characteristics, and an organic thin film transistor manufactured thereby.

  Although the present invention will be described based on the illustrated embodiment, the present invention is not limited to the embodiment. FIG. 1 shows an example of the configuration of an organic organic thin film transistor (hereinafter referred to as an organic TFT). The substrate 30 includes a gate electrode 2, an insulating film 3, a source electrode 4s, a drain electrode 4d, and an organic semiconductor layer 5a. In the organic TFT, a gate electrode 2 is provided on a substrate 30, and an insulating film 3 is provided so as to cover the gate electrode 2. On the insulating film 3, a source electrode 4 s and a drain electrode 4 d are provided by providing a space serving as a channel formation portion made of an organic semiconductor. These are connected by providing the organic semiconductor layer 5 in the space between the source electrode 4s and the drain electrode 4d. In such an organic TFT element 10, for example, a transparent pixel electrode made of ITO or the like is provided on the drain electrode 4d, and these are arranged in a matrix to form a display circuit of a display device. One pixel portion arranged in a matrix is shown in FIG. In addition to the organic TFT portion described above, 7 is a source bus electrode, 8 is a gate bus electrode, and 9 is a transparent pixel electrode.

  In addition, in each figure of FIGS. 1-10, what has the same thing or the same function is shown with the same code | symbol. Hereinafter, the configuration, material, and process of each member of the organic TFT will be described with reference to FIGS.

(Substrate of the first member and substrate of the second member)
The substrate of the first member A (hereinafter referred to as the first substrate) 31 and the substrate of the second member B (hereinafter referred to as the second substrate) 30 shown in FIGS. 3, 6, 7, and 9 will be described. To do. The 1st board | substrate 31 and the 2nd board | substrate 30 are not specifically limited, For example, resin sheets, such as glass, such as soda glass and an alkali free glass, and a flexible plastic film, can be used. Specific examples of the plastic film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polycarbonate (PC), cellulose triacetate (TAC), and cellulose acetate propionate (CAP). ) And the like. By using such a plastic film, the weight can be reduced as compared with the case of using a glass substrate, the portability can be improved, and the resistance to impact can be improved. Further, a metal plate such as stainless steel or brass can be used.

  When a lift-off resist having a photothermal conversion function, which will be described later, is used to irradiate light by irradiating it, it is necessary to irradiate light from the side of the second substrate 30 where the organic TFT is not formed. Moreover, it is necessary to use the board | substrate which can permeate | transmit the wavelength of the light used for light irradiation among the board | substrates mentioned above among the board | substrates mentioned above.

(Gate electrode)
The gate electrode 2 of the second substrate 30 will be described. As a method for forming the gate electrode 2, first, a conductive thin film to be the gate electrode 2 is formed on the second substrate 30. The conductive thin film is not particularly limited as long as it is a conductive material, and a metal material that can sufficiently secure conductivity is preferable. For example, Au, Al, Cr, Ag, Mo, a material obtained by adding doping to these, and the like can be given.

  As a method for forming the above-described conductive thin film, a known method such as vapor deposition or sputtering can be used using the above-described materials as raw materials. Thereafter, the gate electrode 3 can be formed by patterning the conductive thin film using a known photolithography process (resist application, exposure, development) and an etching process.

(Insulating film)
The insulating film 3 that covers the gate electrode 2 will be described. The insulating film 3 is not particularly limited, and various insulating films can be used. In particular, an inorganic oxide film having a high relative dielectric constant is preferable. Examples of the inorganic oxide include silicon oxide, aluminum oxide, tantalum oxide, and titanium oxide. Inorganic nitrides such as silicon nitride and aluminum nitride can also be suitably used.

  As a method for forming the insulating film 3, there are a dry process and a wet process. Examples of the dry process include a vacuum deposition method, a CVD method, a sputtering method, an atmospheric pressure plasma method, and the like. Examples of the wet process include a method by coating, a method by patterning such as printing and inkjet, and the like.

(Source electrode and drain electrode)
The source electrode 4s and the drain electrode 4d on the insulating film 3 will be described. The material and method for forming the source electrode 4s and the drain electrode 4d can be the same as those of the gate electrode 2 described above. First, a conductive thin film to be the source electrode 4 s and the drain electrode 4 d is formed on the insulating film 3. The conductive thin film is not particularly limited as long as it is a conductive material, and a metal material that can sufficiently secure conductivity is preferable. For example, Au, Al, Cr, Ag, Mo, a material obtained by adding doping to these, and the like can be given. As a method for forming the conductive thin film, a known method such as vapor deposition or sputtering can be used with the above-mentioned materials as raw materials. Thereafter, the source and drain electrodes 4s and 4d can be formed by using a known photolithography process (resist application, exposure, development) and an etching process.

  Further, the formation of the transparent pixel electrode 9 made of ITO (Indium Tin Oxide) after forming the source electrode 4s and the drain electrode 4d will be described. As a method for forming the pixel electrode 9, for example, a known method such as vapor deposition or sputtering using ITO as a raw material can be used. Thereafter, the pixel electrode 9 can be formed by performing a known photolithography process (resist application, exposure, development) and an etching process. The second member can be prepared with the contents described so far.

(Self-assembled film)
The self-assembled film will be described. The self-assembled film is preferably a self-assembled monolayer (SAM). The SAM includes, for example, a silane coupling agent. Specific examples of the silane coupling agent include octadecyltrichlorosilane (OTS).

  Silane coupling agents are generally used to improve the physical strength, water resistance, and adhesion of materials. In the manufacture of the organic TFT of the present embodiment, for example, as shown in FIG. 3A, an OTS is provided on the entire surface as the SAM 37 on the first surface of the second member B having the source electrode 4s and the drain electrode 4d. Thereafter, patterning is performed so that OTS remains in a region where the adhesive force is desired to be increased. By forming the pattern of the SAM 37, the adhesive force between the insulating film 3 and the organic semiconductor layer 5 in the space between the source electrode 4s and the drain electrode 4d to which the organic semiconductor layer is connected, which will be described later, is increased. The organic semiconductor layer 5a can be easily formed so as to connect the source electrode 4s and the drain electrode 4d.

  Since the SAM 37 is decomposed when irradiated with ultraviolet rays, the pattern of the SAM 37 can be easily formed by irradiating the photomask 35 with ultraviolet rays L and performing mask exposure, for example, as shown in FIG. . Examples of the ultraviolet light source used for patterning the SAM 37 include a mercury lamp and an excimer lamp. Moreover, it is preferable to use the wavelength of these ultraviolet rays in the range of 150 nm to 300 nm.

  Further, as shown by the SAM 37a in FIG. 6A, the SAM is effective in improving transistor characteristics and reliability by forming a base on which the first organic semiconductor layer 5 is formed on the substrate 42. is there. When a low molecular organic semiconductor typified by pentacene is vacuum-deposited on the SAM 37a to form the first organic semiconductor layer 5, the organic semiconductor molecules are selectively arranged to increase the carrier mobility. An organic TFT formed using such a first organic semiconductor layer 5 can obtain good characteristics (see Example 2).

Moreover, since a favorable monomolecular film is formed on an inorganic base material such as glass or SiO ₂ film, the silane coupling agent is a second substrate provided with an insulating film 3 formed of an inorganic material. 30 is preferably formed. Further, any material that forms a good self-assembled monolayer on the organic semiconductor layer can be provided on the organic semiconductor layer 5 of the first substrate 31 of the first member.

  Further, when Au is used as the material of the source and drain electrodes 4s and 4d, the adhesive force between the source and drain electrodes 4s and 4d and the organic semiconductor layer 5a is obtained by using an organic compound having a thiol group as the self-assembled film. At the same time, the electrical contact resistance can be reduced. As the organic compound having a thiol group, alkanethiol, benzenethiol and the like can be preferably used. In this case, after modifying the Au electrode with an organic compound having a thiol group, a SAM by a silane coupling agent is formed in a channel region which is a space between the source electrode 4s and the drain electrode 4d where the organic semiconductor layer 5a is formed. It is desirable to do.

(Peeling layer)
Next, for example, the peeling layer 39 provided on the first member A shown in FIG. 3 will be described. The release layer 39 is between the first substrate 31 of the first member A and the first organic semiconductor layer 5. In the peeling layer 39, a part of the first organic semiconductor layer 5 of the first substrate 31 is peeled off so that the organic semiconductor layer 5a connecting the source electrode 4s and the drain electrode 4d of the second member B can be formed. It is necessary to do so. On the other hand, the peeling layer 39 needs to prevent the organic semiconductor layer 5 from being peeled from the first substrate 31 in a place where the organic semiconductor layer is unnecessary on the first substrate 31.

In FIG. 3, the first member A and the second member B on which the SAM 37 is formed are overlaid on the region where the organic semiconductor layer is provided so as to connect the source electrode 4s and the drain electrode 4d (FIG. 3D). After heating and pressing, the first member A and the second member B are separated to obtain an organic TFT as the second member (FIG. 3E). For this purpose, it is necessary to select a combination of materials of each layer so that the relationship of the adhesive strength of each layer is as follows.
First region 100 of first surface 102 and organic semiconductor layer 5 (with SAM 37), release layer 39 and first substrate 31> release layer 39 and first organic semiconductor layer 5> first of first surface 102 Region 101 and first organic semiconductor layer 5 (without SAM 37)
As shown in FIG. 3A, the first surface 102 is the surface of the second member B where the source electrode 4s and the drain electrode 4d are present, and the first region 100 is the organic semiconductor layer 5a composed of the source electrode 4s and the drain electrode 4d. A region formed on the first surface so as to connect the second region 101 and a second region 101 mean the remaining region excluding the first region on the first surface. These have the same meaning unless otherwise noted. In the first region 100, the source electrode 4s, the drain electrode 4d, and the insulating film 3 are present in the space between the two electrodes. In addition to the insulating film 3, the second region 101 includes a source bus electrode 7, a gate bus electrode 8, and a pixel electrode 9 as shown in FIG.

  A specific material of the release layer 39 is, for example, paraxylylene. The paraxylylene film can be formed by a CVD method. When the first member A and the second member B are separated as shown in FIG. 3E by satisfying the relationship of the above-mentioned adhesive strength, the organic separated from the first organic semiconductor layer 5 of the first member A The semiconductor layer 5a can be formed so that the source electrode 4s and the drain electrode 4d of the second member B are connected.

  Depending on the combination of materials, the magnitude of the adhesive force due to the presence or absence of the SAM 37 is not sufficient, and the separation film 39 and the first semiconductor layer 5 are bonded to each other by the adhesive force between the surface on which the organic semiconductor layer 5 a is formed via the SAM 37 and the first semiconductor layer 5. In some cases, the adhesive strength with the organic semiconductor layer 5 is greater. In this case, the organic semiconductor layer 5a may not be formed in a region where the SAM 37 is present. In such a case, after forming the pattern of the SAM 37 on the surface on which the organic semiconductor layer 5a that connects the source electrode 4s and the drain electrode 4d is formed, an adhesive 70 is attached to the periphery of the boundary of the SAM 37 as shown in FIG. The adhesive force between the surface on which the semiconductor layer 5a is formed and the organic semiconductor layer 5 may be increased.

  When the adhesive 70 is provided, if the adhesive 70 adheres to the source and drain electrodes 4s, 4d and the channel region between these electrodes, the performance of the organic TFT may be degraded. Therefore, the adhesive 70 is preferably formed around the channel region and the source and drain electrodes 4s and 4d as shown in FIG. When a water-based adhesive is used, when the SAM 37 having water repellency is formed, it is repelled in this region. Therefore, the adhesive is selectively applied only around the channel region and the source and drain electrodes 4s and 4d. Can be easily done. For the application of the adhesive, a printing method such as inkjet, dispenser, flexographic printing or the like can be used.

(Lift-off resist)
Further, as shown in FIGS. 7 and 9, an organic TFT can be formed by introducing a lift-off resist 50 patterned in accordance with the relationship of the adhesive strength between the layers described above. In this case, it is necessary to select a combination of materials of the respective layers having the following relationship of adhesive strength.
First region 100 of first surface 102 and organic semiconductor layer 5 (with SAM 37), peeling layer 39 and first substrate 31> peeling layer 39 and first organic semiconductor layer 5
Further, the peeling layer 39, the first organic semiconductor layer 5, the first organic semiconductor layer 5, and the lift-off resist 50 (with SAM 37)> the second region 101 of the first surface 102 and the lift-off resist 50
The pattern of the lift-off resist 50 can be formed by a known photolithography process. Further, since the lift-off resist 50 is used to easily remove the film or the like originally provided on the lift-off resist from the base material on which the lift-off resist is provided, the adhesive force is generally small. Therefore, even if the first member A and the second member B are superposed and heated and pressed, the adhesive force between the lift-off resist 50 and the first organic semiconductor layer 5 is the adhesive force between the insulating film 3 and the lift-off resist 50. There may be cases where it is not sufficiently large. In order to cope with this, a SAM 37 is provided on the lift-off resist 50. Further, the lift-off resist 50 preferably has a photothermal conversion function in which the adhesive strength is reduced by irradiating light. As shown in FIG. 9, assuming that the lift-off resist 50 has a photothermal conversion function, the adhesive force is further reduced by irradiating the lift-off resist 50 from the second substrate 30 side, and the lift-off resist 50 is removed from the insulating film 3. It can be removed more easily. Specifically, it is preferable that the lift-off resist 50 generate gas from the lift-off resist 50 when irradiated with ultraviolet rays, and as a result, the adhesive force is reduced.

(Protective layer)
Next, the protective layer will be described. As shown in FIG. 6D, it is preferable to provide a protective layer 40 on the organic semiconductor layer 5a for protecting the organic semiconductor from deterioration due to moisture absorption or oxidation. For this purpose, as shown in FIG. 6B, it is necessary to provide a protective layer 40 between the organic semiconductor layer 5 and the release layer 39 in the first substrate 31 of the first member A. As the protective layer 40, an inorganic film such as silicon oxide or silicon nitride, polyvinyl alcohol (PVA), polyvinylphenol (PVP), an acrylic organic film, a polyester organic film, or the like can be used. When the protective layer 40 is provided, it is necessary to select a combination of materials of the respective layers that have the following relationship of adhesive strength for obtaining the organic TFT.
First region of first surface and organic semiconductor layer 5 (with SAM 37), release layer 39 and first substrate 31, organic semiconductor layer 5 and protective layer 40> protective layer 40 and release layer 39> first surface Second region and organic semiconductor layer 5 (without SAM 37)
Further, in the case of providing the protective layer 40, in order to obtain an organic TFT using the lift-off resist described above, it is necessary to select a combination of materials of the respective layers in which the relationship of the adhesive strength of the respective layers is as follows.
First region of first surface and organic semiconductor layer (with SAM), peeling layer and first substrate, protective layer and first organic semiconductor layer> peeling layer and protective layer, peeling layer and protective layer, first layer 1 Organic Semiconductor Layer and Lift-off Resist (with SAM)> One specific method for providing the protective layer 40 on the organic semiconductor layer 5a of the organic TFT is shown in FIG. Shown in (A) to (C). A third substrate 42 provided with a release layer 39a, a SAM 37a, and an organic semiconductor layer 5 is superposed on the first substrate 31 provided with a protective layer 40 on the release layer 39, and heated and pressed to adhere to the third substrate 42. The organic semiconductor layer 5 of the substrate 42 is transferred onto the protective layer 40 provided on the first substrate 31. Thereafter, the contents described above may be used. By doing so, the protective layer 40 can be provided on the organic semiconductor layer 5a, and the first semiconductor layer 5 is formed on the SAM 37a, so that the organic semiconductor molecules are selectively arranged. Since the carrier mobility is increased, the characteristics of the organic TFT can be improved.

(Organic semiconductor)
The organic semiconductor layer 5 will be described. The material forming the organic semiconductor layer 5 is not particularly limited, and for example, pentacene, polythiophene, oligothiophene, P3HT (poly-3-hexylthiophene), phthalocyanine, or a derivative thereof can be used. The method for forming the organic semiconductor layer 5 is not particularly limited, and can be formed by a known method. For example, there is a vacuum evaporation method using resistance heating or an electron beam.

  An organic semiconductor layer having a uniform crystal state can be easily formed on the flat first substrate 31 having no irregularities such as electrodes. By transferring this homogeneous organic semiconductor layer onto the gate insulating film provided with the SAM, an organic TFT element having good characteristics can be formed. In addition, when the second substrate 30 having the gate electrode and the first substrate 31 having the organic semiconductor layer are overlapped with each other, an organic semiconductor layer is provided on the entire surface of the first substrate 31. Since it is good, since the positioning between both substrates is unnecessary, manufacture becomes easy. However, in this case, it is necessary to provide the SAM 37 on the second member B as shown in FIG.

(Heating, pressing)
When the second member B provided with the SAM 37 and the first member A provided with the first organic semiconductor layer 5 are overlapped and heated and pressed, the set temperature and pressure are the insulating film 3 to be used, Depending on the materials such as the SAM 37 and the first organic semiconductor layer 5, the approximate temperature is in the range of 50 ° C. to 200 ° C., and the pressure is in the range of 10,000 Pa to 100,000 Pa.

  Also, the first substrate 31 and the third substrate 42 shown in FIGS. 6 (A) to 6 (C) are superposed, heated, pressed, separated, and then separated to form a first member provided with a protective layer 40. When the above-mentioned second member B and first member A are formed, the temperature and pressure at which the second member B and the first member A are superposed and heated and pressed are preferably lower than the temperature and pressure used.

  In the above description, the bottom-gate / bottom-contact type organic TFT 10 shown in FIG. 1 has been described. However, a bottom-gate / top-contact type organic TFT 10 may be used. A configuration example of the top contact type organic TFT is shown in FIG. An organic TFT 20 shown in FIG. 11A includes a source electrode 4s and a drain electrode 4d on an organic semiconductor layer 5a. When the bottom gate top contact type organic TFT 20 is manufactured, the structure of the second member B described so far is provided up to the insulating film 3 as in the second member B ′ shown in FIG. And the drain electrode 4d is not provided. The second member B ′ shown in FIG. 11B is replaced with the second member B in FIG. 3A as it is, and the first member A and the second member B ′ are overlapped in the same manner as described above. In addition, the first member A and the second member B ′ are separated after heating and pressing. As a result, an organic semiconductor layer can be formed in the first region 100 of the second member B ′. Thereafter, the organic TFT 20 shown in FIG. 11A is manufactured by providing the source electrode 4s and the drain electrode 4d connected to the organic semiconductor layer 5a with the organic semiconductor layer 5a formed on the second member B ′ interposed therebetween. can do.

(Example 1)
This will be described with reference to FIG. (A) to (e) show the manufacturing process in cross-sectional views focusing on the organic TFT portion, and FIGS. 4 and 5 show the second member B from the upper side of the drawing in (c) and (e), respectively. It shows the appearance of the surface. As the second substrate 30, a polyethersulfone (PES) substrate made by Sumitomo Bakelite having a size of 100 mm × 100 mm and a thickness of 200 μm was used. In order to form a 400 × 400 matrix organic transistor array on the second substrate 30, the following were formed in order by sputtering and photolithography (FIG. 3A).
(1) A gate electrode 2 and a gate bus electrode (not shown) made of aluminum.
(2) Insulating film 3 made of SiO ₂ .
(3) Source electrode 4s, drain electrode 4d, and source bus electrode 4d made of gold (Au) (the gate length of the channel portion is 10 μm, and the gate width is 100 μm).
(4) A pixel electrode 9 made of tin-doped indium oxide (ITO).

  Next, the second substrate 30 on which electrodes and the like are formed as described above is immersed in a 5% by weight toluene solution of octadecyltrichlorosilane (OTS) for 3 minutes and subjected to ultrasonic treatment to repel the surface of the second substrate 30. A highly aqueous self-assembled monolayer (SAM) 37 of octadecyltrichlorosilane (OTS) was formed.

  Next, the channel region forming the organic semiconductor layer 5a and the region other than the source and drain electrodes 4s and 4d are irradiated with ultraviolet light L (wavelength 185 nm) by a mercury lamp through the photomask 35 (FIG. 3B). )), And the irradiated SAM was removed leaving the SAM 37 in the first region 100 (FIG. 3 (c), FIG. 4).

  Next, a PES substrate made of Sumitomo Bakelite having a size of 100 mm × 100 mm and a thickness of 200 μm was used as the first substrate 31. A paraxylylene film serving as a peeling layer 39 having a thickness of 200 nm was formed by CVD. A pentacene film, which is a first organic semiconductor layer 5 having a thickness of 500 nm, was formed thereon by a resistance heating vacuum deposition method, thereby forming a first member A. Since the pentacene film is formed on the surface of the flat first substrate 31 via the release layer 39, a film having a uniform crystal grain size can be formed (FIG. 3C). .

  Next, the SAM (OTS) 37 of the second member B and the first organic semiconductor layer (pentacene film) 5 of the first member A are overlapped and heated at a temperature of 100 ° C. and a pressure of 30000 Pa for 3 minutes. The pressed state was obtained (FIG. 3D). Thereafter, the second member B and the first member A were peeled off (FIGS. 3E and 5).

  As a result of peeling, the organic semiconductor layer 5a that connects the source electrode 4s and the drain electrode 4d of the second member is formed, and the organic TFT is completed.

The produced organic TFT array exhibited good transistor characteristics with a uniform crystal state of the pentacene film and little variation. Specifically, it has good transistor characteristics with a mobility of 0.1 cm ² / V · s and an on / off ratio of 105, and the variation in mobility of each organic TFT element constituting the organic TFT array is within a range of about 5%. It was.

(Example 2)
A description will be given with reference to FIG. (A) to (e) show the manufacturing process in a cross-sectional view focusing on the TFT portion. In each of (c) and (e), the state of the surface of the second member B viewed from the upper side of the figure is shown in the example. 4 and 5 are the same as FIG. A description of the same steps as those in Example 1 is omitted.

  In the same manner as in Example 1, the gate electrode 2 to the pixel electrode 9 were formed on the second substrate 30, and the SAM 37 of the first region 100 was further formed (FIG. 6C, FIG. 5). .

  As the third substrate 42, an alkali-free glass substrate having a size of 100 mm × 100 mm and a thickness of 200 μm was used. A paraxylylene film serving as a peeling layer 39a having a thickness of 200 nm was formed on the third substrate 42 by CVD. Next, it was immersed in a 5 mass% toluene solution of octadecyltrichlorosilane (OTS) for 3 minutes and subjected to ultrasonic treatment to form a highly water-repellent SAM 37a on the surface of the release layer 39a. Further, a pentacene film, which is an organic semiconductor layer 5 having a thickness of 500 nm, was formed on the SAM 37a by a resistance heating vacuum deposition method (FIG. 6A). Since the pentacene film is formed on a flat surface, it can be formed as a film having a uniform crystal grain size. Further, since the pentacene film is formed on the SAM 37a, the pentacene molecules on the surface of the SAM 37a become a polycrystalline film in which the directions are aligned.

  Next, as the first substrate 31, a polyethersulfone substrate made of Sumitomo Bakelite having a size of 100 mm × 100 mm and a thickness of 200 μm was used. A paraxylylene film was formed as the peeling layer 39 having a thickness of 200 nm by a CVD method. A 200 nm silicon oxide film was formed thereon as a protective layer 40 by sputtering (FIG. 6A).

  The third substrate 42 and the first substrate 31 were heated and pressed at a temperature of 80 ° C. and a pressure of 20000 Pa (FIG. 6B). Next, the third substrate and the second substrate were peeled off (FIG. 6C). The pentacene film 5 is transferred from the third substrate 42 to the first substrate 31. The surface of the pentacene film transferred to the first substrate 31 was irradiated with ultraviolet rays to remove octadecyltrichlorosilane (OTS) remaining on the surface. The first organic semiconductor layer 5 from which octadecyltrichlorosilane (OTS) has been removed has good molecular orientation and good surface flatness.

  Thereafter, as in Example 1, the second member B and the first member A were heated and pressed (FIG. 6D). Then, the 2nd member B and the 1st member A were peeled off (FIG.6 (e)).

  As a result of peeling, the organic semiconductor layer 5a that connects the source electrode 4s and the drain electrode 4d of the second member is formed, and the organic TFT is completed.

The pentacene film in the produced organic TFT array was able to form an organic semiconductor crystal having a large crystal size and uniform orientation as compared with Example 1, in addition to the uniform crystal state of the film. The transistor characteristics showed good transistor characteristics with a mobility of 0.2 cm ² / V · s and an on / off ratio of 106, and the variation in mobility of each organic TFT element constituting the organic TFT array was within a range of about 2%. .

  In addition, since the protective layer 40 of silicon oxide is formed, there is no deterioration due to oxygen, water vapor, organic solvent, etc., and a highly reliable element with a long life can be obtained.

(Example 3)
A description will be given with reference to FIG. (A) to (e) show the manufacturing process in a cross-sectional view focusing on the TFT portion, and FIG. 8 shows the second member B on which the lift-off resist 50 is patterned in (b) from the upper side of the drawing. It shows the appearance of the surface. A description of the same steps as those in Example 1 is omitted.

  Similarly to Example 1, the formation from the gate electrode 2 to the pixel electrode (not shown) was formed on the second substrate 30 to form the second member B (FIG. 7A).

  A pattern of a lift-off resist film 50 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) is formed on the second member B by photolithography so as to cover the channel region of the organic TFT and the region other than the source and drain electrodes 4s and 4d. It formed in the area | region 101 (FIG.7 (b), FIG. 8).

  Further, the second member B was immersed in a 5% by mass toluene solution of octadecyltrichlorosilane (OTS) for 3 minutes and subjected to ultrasonic treatment, and the surface was highly water-repellent octadecyltrichlorosilane self-assembled monolayer (SAM) 37. Was formed (FIG. 7C).

  Next, as in Example 1, a release layer 39 (paraxylylene film) and an organic semiconductor layer 5 (pentacene) were formed on the first substrate 31 to form a first member A. The second member B and the first member A were superposed and heated and pressed at a temperature of 100 ° C. and a pressure of 30000 Pa for 3 minutes (FIG. 7D). Thereafter, the first substrate and the second substrate were peeled off (FIG. 7E).

  As a result of peeling, the organic semiconductor layer 5a that connects the source electrode 4s and the drain electrode 4d of the second member is formed, and the organic TFT is completed.

  The produced organic TFT array showed good transistor characteristics equivalent to Example 1. Since the lift-off resist is easily peeled off from the second member B, the organic semiconductor layer 5a is formed satisfactorily and the occurrence of defects in the organic TFT is small.

Example 4
A description will be given with reference to FIG. (A) to (e) show the manufacturing process in cross-sectional views focusing on the TFT portion. In the manufacturing process (d), the irradiation with the ultraviolet ray L is different from that in the third embodiment.

  As a material of the lift-off resist 50, a material having a photothermal conversion function and generating gas by heat generated by light irradiation was used. The second member B and the first member A are prepared by the same method as in Example 3, and after superposing them, heating and pressing, ultraviolet rays L (wavelength 185 nm) are emitted from the second substrate 30 side by an ultraviolet lamp. Irradiated. Thereafter, the second member B and the first member A were peeled off.

  Since the lift-off resist 50 is thermally decomposed by the photothermal conversion function and gas is generated, the adhesive force is reduced, so that the adhesive force between the lift-off resist 50 and the insulating film 3 is hardly felt, and the second member B and the first member The member A could be easily peeled off. As a result of peeling, the organic semiconductor layer 5a that connects the source electrode 4s and the drain electrode 4d of the second member is formed, and the organic TFT is completed.

  The produced organic transistor array showed good transistor characteristics equivalent to Example 1. The occurrence of defects in the organic TFT due to poor formation of the organic semiconductor layer 5a was even less than in Example 3.

It is a figure which shows the example of a structure of organic TFT. It is a figure which shows the example in which organic TFT is used for the pixel of a display device. It is a figure explaining the example of the manufacturing process of organic TFT. It is the figure which looked at the mode for 1 pixel where SAM is patterned from the upper part of the 1st substrate. It is the figure which looked at the mode for 1 pixel which has the completed organic TFT from the upper part of the 1st board | substrate. It is a figure explaining the example of the manufacturing process of organic TFT. It is a figure explaining the example of the manufacturing process of organic TFT. It is a figure which shows a mode that the lift-off resist is pattern-formed on the 1st board | substrate. It is a figure explaining the example of the manufacturing process of organic TFT. It is a figure which shows a mode that the adhesive agent is attached to SAM periphery part. It is a figure which shows the example of a structure of organic TFT.

Explanation of symbols

2 Gate electrode 3 Insulating film 4 s Source electrode 4 d Drain electrode 5 Organic semiconductor layer 7 Source bus electrode 8 Gate bus electrode 9 Pixel electrode 10, 20 Organic TFT
30 Second substrate 31 First substrate 35 Photomask 37, 37a SAM
39, 39a Peeling layer 40 Protective layer 42 Third substrate 50 Lift-off resist film 70 Adhesive 100 First region 101 Second region 102 First surface A First member B, B ′ Second member L Ultraviolet irradiation light

Claims (14)

Method for manufacturing organic thin film transistor having at least source electrode, drain electrode, organic semiconductor layer connecting source electrode and drain electrode on substrate, gate electrode and organic thin film transistor having insulating film between organic semiconductor layer and gate electrode In
A first organic semiconductor layer that provides the substrate and the organic semiconductor layer; and further, between the substrate and the first organic semiconductor layer, after heating and pressing the first organic semiconductor layer from the substrate. Preparing a first member having a release layer having a low adhesive force, and a second member having a surface having an insulating film on the substrate as a first surface;
The release layer and the release layer on either the first region where the organic semiconductor layer is formed on the first surface or the surface of the portion of the first organic semiconductor layer that provides the organic semiconductor layer Self-organization that increases the adhesive force between the first surface and the first organic semiconductor layer, which is smaller even after heating and pressing than the adhesive force with the layer in contact with the layer, by heating and pressing Forming a film;
Superimposing the first member and the second member in a direction in which the first organic semiconductor layer of the first member and the first surface of the second member face each other;
Heating and pressing the first member and the second member;
The method of manufacturing an organic thin film transistor, wherein the step of separating the first member and the second member is performed in this order. 2. The method of manufacturing an organic thin film transistor according to claim 1, wherein the source electrode and the drain electrode are provided as uppermost layers on the first surface of the second member to be prepared. After the step of separating the first member and the second member, a step of providing the source electrode and the drain electrode connected to the organic semiconductor layer with the organic semiconductor layer formed on the second member in between. The method for producing an organic thin film transistor according to claim 1, wherein the method is performed. The first member has a substrate, the release layer, and the first organic semiconductor layer in this order, and further between the release layer and the first organic semiconductor layer, the heating and pressing after the pressing 4. The protective layer according to claim 1, further comprising a protective layer having an adhesive force between the substrate and the release layer and an adhesive force between the first organic semiconductor layer and the release layer that is smaller than the adhesive force between the substrate and the release layer. A method for producing an organic thin film transistor according to claim 1. 5. The method of manufacturing an organic thin film transistor according to claim 1, wherein in the step of forming the self-assembled film, a self-assembled film is formed in the first region. The method for producing an organic thin film transistor according to any one of claims 1 to 5, wherein the self-assembled film is a self-assembled monomolecular film. Production of an organic thin film transistor having an insulating film between at least a source electrode, a drain electrode, an organic semiconductor layer connecting the source electrode and the drain electrode, a gate electrode, and the organic semiconductor layer and the gate electrode on a substrate In the method
A first organic semiconductor layer that provides a substrate and an organic semiconductor layer that serves as the organic semiconductor layer, and further, the substrate and the first organic semiconductor layer between the substrate and the first organic semiconductor layer. A step of preparing a first member having a peeling layer having a small adhesive force after heating and pressing, and a second member having a surface having an insulating film forming the first surface on the substrate as a first surface;
In the remaining second region excluding the first region where the organic semiconductor layer is formed on the first surface, the adhesive force with the second region after heating and pressing is such that the release layer and the first region Forming a lift-off resist smaller than the adhesive strength of the organic semiconductor layer;
The surface after the lift-off resist is formed on the first surface or the surface of the first region and the first organic semiconductor layer by heating and pressing the first organic semiconductor layer. The adhesive force is made larger than the adhesive force between the release layer and the layer that is in contact with the release layer, and the adhesive force between the first organic semiconductor layer and the lift-off resist is increased on the first surface. Forming a self-assembled film larger than the adhesive force between the second region and the lift-off resist;
Superimposing the first organic semiconductor layer of the first member and the self-assembled film of the second member facing each other;
Heating and pressing the first member and the second member;
The method of manufacturing an organic thin film transistor, wherein the step of separating the first member and the second member is performed in this order. 8. The method of manufacturing an organic thin film transistor according to claim 7, wherein the source electrode and the drain electrode are provided as uppermost layers on the insulating film of the second member to be prepared. After the step of separating the first member and the second member, a step of providing the source electrode and the drain electrode connected to the organic semiconductor layer with the organic semiconductor layer formed on the second member in between. The method for producing an organic thin film transistor according to claim 7, wherein the method is performed. The first member has a substrate, the release layer, and the first organic semiconductor layer in this order, and further between the release layer and the first organic semiconductor layer, the heating and pressing after the pressing 10. The protective layer according to claim 7, further comprising a protective layer having an adhesive force between the substrate and the release layer and an adhesive force between the first organic semiconductor layer and the release layer that is smaller than the adhesive force between the substrate and the release layer. A method for producing an organic thin film transistor according to claim 1. 11. The self-assembled film is formed on the surface after the lift-off resist is formed on the first surface in the step of forming the self-assembled film. The manufacturing method of the organic thin-film transistor of description. The said lift-off resist has a photothermal conversion function in which the adhesive force of the said 1st surface side falls by irradiating light from the 2nd member side, It is any one of Claim 7 thru | or 11 characterized by the above-mentioned. Manufacturing method of organic thin-film transistor. 13. The method of manufacturing an organic thin film transistor according to claim 12, wherein the light conversion function of the lift-off resist is such that gas is generated when the light is irradiated and adhesive force is reduced. The organic thin-film transistor manufactured by the manufacturing method of the organic thin-film transistor as described in any one of Claims 1 thru | or 13.

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