JP2015088715A - Method of manufacturing organic thin-film transistor and organic thin-film transistor - Google Patents

Abstract

An organic thin film transistor having a uniform film thickness of an organic semiconductor layer, and an organic thin film transistor formed by the method are provided.
A first step of patterning a gate electrode, a second step of forming an insulating layer to be a gate insulating layer so as to cover the gate electrode, and an organic semiconductor layer on the insulating layer A third step of patterning the first sacrificial film; a fourth step of etching the insulator layer to form a gate insulating layer; and a liquid repellent treatment for the coating solution to be the organic semiconductor layer on the surface. This problem is solved by performing step 5, the sixth step of removing the first sacrificial film, and the seventh step of applying the coating solution to the surface.
[Selection] Figure 1

Description

  The present invention relates to a method for producing an organic thin film transistor using an organic semiconductor material, and an organic thin film transistor produced by the production method.

  Organic semiconductor materials can be used in devices that use logic circuits such as TFTs (thin film transistors), RFIDs (RF tags) and memories used in liquid crystal displays and organic EL displays because they can be reduced in weight, cost, and flexibility. An organic thin film transistor (organic TFT) having an organic semiconductor layer (organic semiconductor film) made of is used.

In organic thin film transistors, it is important to improve switching characteristics. For this purpose, it is necessary to improve the field effect mobility to increase the on-current and to suppress the off-current (leakage current).
In order to suppress the off current, it is important that the organic semiconductor layer is appropriately patterned so that the organic semiconductor film is not formed in an unnecessary region other than the element portion.

In the manufacture of an organic thin film transistor, a method using a coating solution (coating solution) containing an organic solvent and an organic semiconductor material is known as a method for forming an organic semiconductor layer.
In Patent Document 1, as a method capable of forming an organic semiconductor layer only in a target region and simultaneously forming a plurality of organic thin film transistors, the wettability (lyophilicity and liquid repellency) to a coating solution for forming the organic semiconductor layer is disclosed. Is described.
Specifically, in the method for producing an organic thin film transistor described in Patent Document 1, a hydrophobic substrate is used as a substrate on which the organic thin film transistor is formed, and a hydrophilic region is formed in a pattern on the surface of the substrate. . Next, a lyophilic functional layer made of an insulating material and having high lyophilicity with respect to the organic solvent is formed on the hydrophilic region. Thereafter, a coating solution for forming the organic semiconductor layer is applied to form the organic semiconductor layer.
According to this method, a lyophilic region and a liquid repellent region are partitioned (formed in a pattern) with respect to the coating solution for forming the organic semiconductor layer on the surface of the substrate. A coating solution can be selectively applied to a region, and an appropriately patterned organic semiconductor layer can be formed only in a target region.

Here, when the organic semiconductor material is a crystalline material, it is important to align the crystal axes of the organic semiconductor in order to form an organic thin film transistor having high mobility.
However, as in Patent Document 1, just dividing the lyophilic region and the liquid repellent region with respect to the coating solution aligns the crystal axis direction of the independently formed organic semiconductor layer. Have difficulty.

On the other hand, in Patent Document 2, as a formation region of an organic semiconductor layer, a solution accumulation region that is mainly connected to each other and is a solution narrowing region narrower than the solution accumulation region. The solution accumulation area and the solution constriction area are made lyophilic, and the other areas are liquid repellent, so that the coating solution can be selectively supplied to the solution accumulation area and the solution confinement area. Have been described.
According to this method, since the coating solution is dried from the narrow solution narrowing region, it is possible to control the crystal growth direction, thereby aligning the crystal axis direction of the organic semiconductor layer.

JP 2009-212127 A JP 2012-44110 A

  By the way, in order to obtain an organic thin film transistor with good characteristics, in addition to suppressing the formation of the organic semiconductor material film in such an unnecessary region and aligning the crystal axis of the organic thin film crystal, the film is formed on the organic semiconductor layer. It is also important that there is no uneven thickness.

However, the method disclosed in Patent Document 1 can suppress the formation of an organic semiconductor material film in an unnecessary region, and the method disclosed in Patent Document 2 achieves the respective purposes of aligning the crystal axes of the organic thin film crystals. Although it is possible, it is difficult to suppress unevenness in the thickness of the organic semiconductor layer.
Therefore, the organic thin film transistor array produced by the conventional manufacturing method causes variations in transistor characteristics such as the on-current and the threshold voltage V _th between the organic thin film transistors due to the uneven thickness of the organic semiconductor layer. For example, it may be difficult to use various displays and sensors as switching devices.

  An object of the present invention is to solve such problems of the prior art, and a method for producing an organic thin film transistor having an organic semiconductor layer having an organic semiconductor layer in which film thickness unevenness is suppressed, and to be produced by this production method An organic thin film transistor is provided.

In order to achieve such an object, the organic thin film transistor manufacturing method of the present invention includes a gate electrode formed on a base material, a gate insulating layer formed to cover the gate electrode, and a gate insulating layer formed on the gate insulating layer. An organic semiconductor layer having a source electrode and a drain electrode formed on the organic semiconductor layer,
The organic semiconductor layer is formed using a coating solution containing an organic semiconductor material to be an organic semiconductor layer, and
A first step of patterning the gate electrode; a second step of covering the gate electrode to form an insulator layer serving as a gate insulating layer; and a first sacrifice corresponding to the organic semiconductor layer on the insulator layer A third step of patterning the film; a fourth step of etching the insulator layer to form a gate insulating layer; and a liquid repellency treatment for the coating solution on at least one surface of the gate insulating layer and the substrate. An organic process comprising performing a fifth step, a sixth step of removing the first sacrificial film, and a seventh step of applying a coating solution to at least one surface of the gate insulating layer and the base material A method for manufacturing a thin film transistor is provided.

In such a method for producing an organic thin film transistor of the present invention, it is preferable to perform a lyophilic treatment on the coating solution at a position where the first sacrificial film is removed between the sixth step and the seventh step.
In the seventh step, an adsorbent that adsorbs the coating solution is preferably disposed on at least one of the gate insulating layer and the base material.
The first step includes a step A for patterning a second sacrificial film on the substrate, a step B for etching the surface of the substrate until the depth corresponds to the thickness of the gate electrode, a second step It is preferable to include a step C of forming a gate electrode material on the surface of the sacrificial film and the base material and a step D of removing the second sacrificial film.
Furthermore, in the fourth step, it is preferable to perform etching until the base material is exposed except in the region where the first sacrificial film is formed.

The organic thin film transistor of the present invention includes a gate electrode formed on a base material, a gate insulating layer formed to cover the gate electrode, and a coating solution containing an organic semiconductor material formed on the gate insulating layer. An organic semiconductor layer formed using a source electrode and a drain electrode formed on the organic semiconductor layer; and
The organic semiconductor layer is formed on the convex portion of the gate insulating layer protruding from the periphery, and further, a film that is liquid repellent with respect to the coating solution except for the surface on which the organic semiconductor layer is formed, including the side surface of the convex portion An organic thin film transistor is provided which is covered with

In such an organic thin film transistor of the present invention, it is preferable that the base material has a concave portion, the gate electrode is inserted into the concave portion, and the surface of the gate electrode is flush with the surface of the base material.
Furthermore, the organic semiconductor layer and the gate insulating layer have the same shape and size in the surface direction of the base material, except for the formation region of the organic semiconductor layer and the gate insulating layer, and the formation region of the source electrode and the drain electrode, It is preferable that the surface of the substrate is exposed.

According to the present invention, it is possible to obtain an organic thin film transistor having an organic semiconductor layer excellent in film thickness uniformity by suppressing the film thickness unevenness of the organic semiconductor layer.
Therefore, according to the present invention, it is possible to obtain an organic thin film transistor array suitable as a switching device for various displays, sensors, and the like, in which there is no variation in on-current of each organic thin film transistor and variation in threshold voltage V _th .

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows an example of the organic thin-film transistor of this invention, Comprising: (A) shows sectional drawing, (B) shows a top view, respectively. It is a conceptual diagram for demonstrating the manufacturing method of the organic thin-film transistor shown in FIG. 1, Comprising: (A) shows sectional drawing, (B) shows a top view, respectively. It is a conceptual diagram for demonstrating the manufacturing method of the organic thin-film transistor shown in FIG. 1, Comprising: (A) shows sectional drawing, (B) shows a top view, respectively. It is a conceptual diagram for demonstrating the manufacturing method of the organic thin-film transistor shown in FIG. 1, Comprising: (A) shows sectional drawing, (B) shows a top view, respectively. It is a conceptual diagram for demonstrating the manufacturing method of the organic thin-film transistor shown in FIG. 1, Comprising: (A) shows sectional drawing, (B) shows a top view, respectively. It is a conceptual diagram for demonstrating the manufacturing method of the organic thin-film transistor shown in FIG. 1, Comprising: (A) shows sectional drawing, (B) shows a top view, respectively. It is a conceptual diagram for demonstrating the manufacturing method of the organic thin-film transistor shown in FIG. 1, Comprising: (A) shows sectional drawing, (B) shows a top view, respectively. It is a conceptual diagram for demonstrating the manufacturing method of the organic thin-film transistor shown in FIG. 1, Comprising: (A) shows sectional drawing, (B) shows a top view, respectively. It is a conceptual diagram for demonstrating the manufacturing method of the organic thin-film transistor shown in FIG. 1, Comprising: (A) shows sectional drawing, (B) shows a top view, respectively. It is a conceptual diagram for demonstrating the manufacturing method of the organic thin-film transistor shown in FIG. 1, Comprising: (A) shows sectional drawing, (B) shows a top view, respectively. It is a conceptual diagram for demonstrating the manufacturing method of the organic thin-film transistor shown in FIG. 1, Comprising: (A) shows sectional drawing, (B) shows a top view, respectively. It is a conceptual diagram for demonstrating the manufacturing method of the organic thin-film transistor shown in FIG. 1, Comprising: (A) shows sectional drawing, (B) shows a top view, respectively. It is a figure which shows notionally another example of the organic thin-film transistor of this invention, Comprising: (A) shows sectional drawing, (B) shows a top view, respectively. It is a figure which shows notionally another example of the organic thin-film transistor of this invention, Comprising: (A) shows sectional drawing, (B) shows a top view, respectively. It is a figure which shows notionally another example of the organic thin-film transistor of this invention, Comprising: (A) shows sectional drawing, (B) shows a top view, respectively. BRIEF DESCRIPTION OF THE DRAWINGS It is a conceptual diagram for demonstrating the Example of this invention, Comprising: (A) shows sectional drawing, (B) shows a top view, respectively. It is a conceptual diagram for demonstrating the Example of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a conceptual diagram for demonstrating the Example of this invention, Comprising: (A) shows sectional drawing, (B) shows a top view, respectively. (A)-(D) are the conceptual diagrams for demonstrating the comparative example of this invention.

  Hereinafter, the organic thin film transistor manufacturing method and the organic thin film transistor of the present invention will be described in detail based on the preferred embodiments shown in the accompanying drawings.

  In FIG. 1, an example of the organic thin-film transistor of this invention formed by an example of the manufacturing method of the organic thin-film transistor of this invention is shown notionally. 1A is a cross-sectional view, and FIG. 1B is a plan view. Moreover, (A) is the aa sectional view of (B).

  An organic thin film transistor 10 shown in FIG. 1 basically includes a base material 12, a gate electrode 14 formed on the base material 12, a gate insulating layer 16 formed so as to cover the gate electrode 14, and a gate insulating layer. 16, an organic semiconductor layer 18 formed on a predetermined position (protrusion 16 a described later), a source electrode 20 formed on the organic semiconductor layer 18 from the surface of the gate insulating layer 16, and a source electrode And a drain electrode 24 formed over the organic semiconductor layer 18 from the surface of the gate insulating layer 16 so as to face the gate insulating layer 16 (in FIG. 1, a liquid repellent film 32 and The lyophilic film 34 is omitted).

  In the organic thin film transistor 10 of the present invention, the size, shape, thickness, etc. of each part of the gate electrode 14, the gate insulating layer 16, the organic semiconductor layer 18, the source electrode 20, the drain electrode 24, etc. Depending on the material for forming the part, the size of the organic thin film transistor 10 to be produced, the arrangement of the organic thin film transistor 10, the performance required for the organic thin film transistor 10 (organic thin film transistor array), etc. You can decide.

  Hereinafter, with reference to FIGS. 2-12, the manufacturing method of the organic thin-film transistor 10 and the organic thin-film transistor of this invention are demonstrated in detail by demonstrating the manufacturing method of the organic thin-film transistor 10. FIG. 2 to 12, (A) is a cross-sectional view, (B) is a plan view, and (A) is a cross-sectional view taken along the line aa in (B), as in FIG. 1.

In the method of manufacturing the organic thin film transistor 10 shown in FIG. 1, first, as conceptually shown in FIG. 2, the gate electrode 14 is formed on the surface of the substrate 12.
In the present invention, as the substrate 12, various sheet-like materials made of various materials used in organic thin film transistors can be used.
Specific examples include plate-like materials (sheet-like materials / films) made of various materials such as metal, ceramic, glass, and plastic.

Among these, a plastic film is preferably used in that a flexible organic thin film transistor (array) can be formed.
Specific examples of the plastic film material that can be used for the substrate 12 include polyester resin, methacrylic resin, methacrylic acid-maleic acid copolymer, polystyrene resin, fluorine resin, polyimide, fluorinated polyimide resin, and polyamide resin. , Polyamideimide resin, polyetherimide resin, cellulose acylate resin, polyurethane resin, polyetheretherketone resin, polycarbonate resin, cycloaliphatic polyolefin resin, polyarylate resin, polyethersulfone resin, polysulfone resin, cycloolefin copolymer, Examples thereof include thermoplastic resins such as a fluorene ring-modified polycarbonate resin, an alicyclic ring-modified polycarbonate resin, a fluorene ring-modified polyester resin, and an acryloyl compound.

In the present invention, the substrate 12 may have a multilayer structure such as a structure in which a plurality of films are bonded together.
Moreover, in the manufacturing method of this invention, in order to manufacture the organic thin-film transistor 10 suitably, a glass plate (glass carrier) etc. are stuck as a support body to the above plastic films as needed. Alternatively, the organic thin film transistor 10 may be produced as shown below, and after the organic thin film transistor 10 is produced, the organic thin film transistor 10 and the support may be peeled off.

  As described above, in the manufacture of the organic thin film transistor 10 shown in FIG. 1, first, the gate electrode 14 is patterned on the surface of the base 12 as shown in FIG. 2 (first step).

As the forming material of the gate electrode 14, various known materials that are used as gate electrodes in organic thin film transistors can be used.
Examples include metals such as aluminum, chromium, copper, molybdenum, tungsten, gold, and silver, alloys, transparent conductive oxides (TCO) such as indium tin oxide (ITO), polyethylenedioxythiophene-polystyrenesulfonic acid (PEDOT- Examples thereof include conductive polymers such as PSS) and laminated structures thereof.

In addition, as the pattern forming method of the gate electrode 14, various known methods corresponding to the forming material can be used.
As an example, a method using a vapor phase film formation method (vapor phase deposition method) such as sputtering or vacuum vapor deposition and photolithography, a vapor phase film formation method and a shadow mask (a mask covering a non-formation part (non-film formation part)) ) And a method by printing.

  Next, as conceptually shown in FIG. 3, an insulator layer 28 to be the gate insulating layer 16 is formed on the entire surface of the base material 12 on which the gate electrode 14 is formed (second step).

Similarly, as the material for forming the insulator layer 28, various known materials that are used as gate insulating layers in organic thin film transistors can be used.
Examples include silicon oxide (SiO _x ), magnesium oxide, aluminum oxide (alumina), titanium oxide, germanium oxide, yttrium oxide, zirconium oxide, niobium oxide, tantalum oxide and other metal oxides, silicon nitride (SiN _x ), etc. Examples include metal nitride, metal nitride oxide (metal oxynitride) such as silicon nitride oxide (SiO _x N _y ), inorganic materials such as diamond-like carbon (DLC), various polymer materials, and laminated structures thereof. The

As the method for forming the insulator layer 28, various known methods depending on the material can be used.
As an example, various chemical vapor deposition methods (CVD) including various physical vapor deposition methods (PVD) such as sputtering, vacuum deposition, ion plating, and atomic layer deposition methods (ALD method or ALE method). ), Coating method, printing method, transfer method and the like.

  Next, as conceptually shown in FIG. 4, the first sacrificial film 30 is patterned according to the formation position of the organic semiconductor layer 18 (third step).

For the first sacrificial film 30, various known materials that are used as sacrificial films in the manufacture of semiconductor devices and the like can be used.
As an example, various photoresists are preferably used, but metals, alloys, metal oxides, metal nitrides, metal nitride oxides (metal oxynitrides), DLC, various polymer materials, laminated structures of these, etc. Are used as appropriate.

As the pattern forming method of the first sacrificial film 30, various known methods depending on the material can be used.
As an example, a photolithography method, a printing method, a transfer method, and the like are exemplified.

After patterning the first sacrificial film 30, as shown conceptually in FIG. 5, the insulator layer 28 is etched to form the gate insulating layer 16 (fourth step).
Here, a first sacrificial film 30 is formed on the insulator layer 28 corresponding to the position where the organic semiconductor layer 18 is formed. Therefore, the gate insulating layer 16 formed by etching the insulator layer 28 is provided with a convex portion 16a protruding from the periphery at the position where the first sacrificial film 30 is formed.

For the etching of the insulator layer 28, various known methods can be used depending on the material for forming the insulator layer 28 (that is, the gate insulating layer 16).
Therefore, the etching of the insulator layer 28 can be performed by dry etching such as reactive ion etching (RIE) or plasma etching, or wet etching using an etchant or an organic solvent that dissolves the insulator layer 28, as long as the target accuracy can be ensured. good.

When the gate insulating layer 16 is formed by etching, as shown conceptually in FIG. 6, a liquid repellent treatment is performed on the surface of the gate insulating layer 16 with respect to the coating solution for forming the organic semiconductor layer 18 (fifth step). ). In the example shown in FIG. 6, a liquid repellent film 32 that exhibits liquid repellency with respect to the coating solution is formed on the surface of the gate insulating layer 16 by liquid repellent treatment.
Here, at this time, the first sacrificial film 30 remains on the convex portion 16 a of the gate insulating layer 16. Therefore, the liquid repellent treatment is performed on the etched portion of the insulator layer 28 (including the side surface of the convex portion 16a).

The liquid repellent treatment may be performed by a known method according to a coating solution (an organic solvent contained in the coating solution) for forming the organic semiconductor layer 18.
As an example, a method of forming a liquid repellent film 32 as shown in FIG. 6 by applying or vapor-depositing a solution containing a compound having liquid repellency to a coating solution and then cleaning and drying, an electron beam ( Examples thereof include a method for performing a surface treatment for imparting liquid repellency using EB). In particular, coating or vapor deposition of a solution containing a silane compound, an organic phosphate compound, or a carboxylic acid compound that forms a self-assembled monomolecular (SAM) film on the surface of the gate insulating layer 16 (the etched portion of the insulator layer 28). The method of performing is preferably used.
For the application of the solution for forming the liquid repellent film 32, various known liquid application methods such as spin coating, doctor knife, gravure coating, dip coating, and dropping of droplets can be used. Further, depending on the liquid repellent treatment method, the liquid repellent film 32 is not formed, and only the surface of the gate insulating layer 16 (the etched portion of the insulating layer 28) is modified.

When the liquid repellent treatment is performed, the first sacrificial film 30 is removed as conceptually shown in FIG. 7 (sixth step).
The removal of the first sacrificial film 30 can use various known methods depending on the material for forming the first sacrificial film 30.
As an example, a method of dissolving and removing the first sacrificial film 30 using a dissolvable etchant, an organic solvent, or the like, a method of peeling and removing the first sacrificial film 30, and polishing the first sacrificial film 30 Examples of the removal method are illustrated.

  After the removal of the first sacrificial film 30, if necessary, as conceptually shown in FIG. 8, the position where the first sacrificial film 30 is removed, that is, on the surface of the convex portion 16 a of the gate insulating layer 16. A lyophilic process is performed on the coating solution for forming the organic semiconductor layer 18. In the example shown in FIG. 8, a lyophilic film 34 that exhibits lyophilicity with respect to the coating solution is formed on the surface of the convex portion 16a of the gate insulating layer 16 by lyophilic processing.

The lyophilic treatment may be performed by a known method according to a coating solution (an organic solvent contained in the coating solution) for forming the organic semiconductor layer 18.
As an example, a lyophilic solution that exhibits lyophilicity with respect to the coating solution as shown in FIG. Examples include a method of forming a conductive film 34, a method of performing surface treatment for imparting lyophilicity such as ultraviolet ozone treatment, corona treatment, plasma treatment, etc. to the surface of the convex portion 16a using a shadow mask or photolithography. The In particular, a method of applying or vapor-depositing a solution containing a silane compound, an organic phosphate compound, or a carboxylic acid compound that forms a SAM film on the surface of the convex portion 16a of the gate insulating layer 16 is preferably used.
Note that the application of the solution for forming the lyophilic film 34 may be performed in the same manner as the application of the solution containing the liquid repellent compound. Further, depending on the method of lyophilic treatment, the lyophilic film 34 is not formed, and only the surface of the convex portion 16a of the gate insulating layer 16 is modified.

  In addition, when the gate insulating layer 16 has sufficient lyophilicity (sufficient application property) with respect to the coating solution which forms the organic-semiconductor layer 18, this lyophilic process is unnecessary.

Next, as conceptually shown in FIG. 9, a coating solution 38 to be the organic semiconductor layer 18 is applied to the surface of the gate insulating layer 16 (the liquid repellent film 32 and the lyophilic film 34) (seventh step). ).
Here, in the example shown in FIG. 9, as a preferred embodiment, a solution adsorbent 36 that adsorbs the coating solution 38 is provided on the surface of the gate insulating layer 16 (liquid repellent film 32), and the coating solution 38 is applied. Yes.

  The coating solution 38 is obtained by dissolving an organic semiconductor material to be the organic semiconductor layer 18 in an organic solvent or the like.

In the present invention, as the organic semiconductor material, various known materials used for an organic semiconductor layer formed by a so-called wet process (wet process) such as a coating method can be used in the manufacture of an organic thin film transistor.
Specifically, pentacene derivatives such as 6,13-bis (triisopropylsilylethynyl) pentacene (TIPS pentacene), and anthradithiophene derivatives such as 5,11-bis (triethylsilylethynyl) anthradithiophene (TES-ADT) , benzodithiophene (BDT) derivatives, benzothiophene thieno benzothiophene (BTBT) derivatives such as dioctyl benzothienopyridine benzothiophene (C ₈ -BTBT), Gina shift thienothiophene (DNTT) derivatives, Gina shift benzodithiophene (DNBDT) derivatives, 6,12-dioxaanthanthrene (perixanthenoxanthene) derivative, naphthalenetetracarboxylic acid diimide (NTCDI) derivative, perylenetetracarboxylic acid diimide (PTCDI) derivative, polythiophene derivative, poly ( , 5-bis (thiophen-2-yl) thieno [3,2-b] thiophene) (PBTTT) derivatives, tetracyanoquinodimethane (TCNQ) derivatives, oligothiophenes, phthalocyanines, fullerenes, etc. .

Various organic solvents (solvents) can be used as long as the organic solvent contained in the coating solution 38 can dissolve the organic semiconductor material to be used.
For example, when the organic semiconductor material is TIPS pentacene, TES-ADT, C ₈ -BTBT, etc., toluene, xylene, mesitylene, 1,2,3,4-tetrahydronaphthalene (tetralin), chlorobenzene, dichlorobenzene, anisole Aromatic compounds such as

The concentration of the coating solution 38 may be set as appropriate according to the organic semiconductor material and organic solvent to be used, the thickness of the organic semiconductor layer 18 to be formed, and the like.
Moreover, in the manufacturing method of this invention, you may contain a thickener, a crystallizing agent, antioxidant, etc. in this coating solution other than an organic-semiconductor material and an organic solvent as needed.

  Furthermore, as a method for applying the coating solution 38 to the surface of the gate insulating layer 16, various known liquid application methods such as spin coating, doctor knife, gravure coating, dip coating, and droplet dropping can be used. .

When the coating solution 38 is applied to the surface of the gate insulating layer 16 (the liquid repellent film 32 and the lyophilic film 34) in this way, the coating solution 38 is dried as shown in FIG. 18 is formed.
As described above, the gate insulating layer 16 is formed with the liquid repellent film 32 that exhibits liquid repellency with respect to the coating solution 38 except for the surface of the convex portion 16a (liquid repellent treatment is performed). . Moreover, the lyophilic film | membrane 34 which expresses the lyophilic property with respect to the coating solution 38 is formed in the surface of the convex part 16a as needed (the lyophilic process is performed).
Accordingly, the organic semiconductor layer 18 is not formed in a region other than the convex portion 16a of the gate insulating layer 16, but is selectively formed on the surface of the convex portion 16a.

Here, in the example shown in FIG. 10 (FIG. 9), as a preferred embodiment, a solution adsorbing body 36 that adsorbs the coating solution 38 is provided on the surface of the gate insulating layer 16 (liquid repellent film 32).
Therefore, as conceptually shown in FIG. 10, the coating solution 38 is sequentially dried from the side (left side in the figure) away from the solution adsorbing body 36 while being pulled by the solution adsorbing body 36. 18 is formed. In the example shown in FIG. 10, this makes it possible to align the crystal axis direction of the organic semiconductor layer 18 (film made of an organic semiconductor), and to manufacture the organic thin film transistor 10 with high mobility.

Various materials can be used as the material for forming the solution adsorbent 36 as long as the material can adsorb the coating solution 38.
As an example, the coating solution 38 may be adsorbed by the effect of meniscus (surface tension) such as metal, glass, ceramic, and plastic, such as silicon rubber, butyl rubber, various (meth) acrylate polymers, etc. The solution adsorbent 36 may be formed of a porous material such as a synthetic resin that absorbs a coating solution (an organic solvent contained in the coating solution), plastic, or an inorganic ceramic material, and the coating solution 38 may be adsorbed.

  The arrangement position of the solution adsorbent 36 such as the distance from the formation position (convex portion 16a) of the organic semiconductor layer 18 depends on the size of the organic thin film transistor 10, the formation interval of the organic thin film transistor 10, the coating method of the coating solution 38, and the like. It can be set as appropriate.

In addition, the organic thin film transistor 10 is generally formed by arranging a plurality of organic thin film transistors 10 on the substrate 12 (referred to as an organic thin film transistor array).
Here, the solution adsorbent 36 may be provided corresponding to each organic thin film transistor 10, or one may be provided corresponding to the plurality of organic thin film transistors 10.
For example, when the organic thin film transistor 10 is two-dimensionally arranged in the xy directions orthogonal to each other, for example, it extends in the x direction corresponding to the plurality of organic thin film transistors 10 arranged in the x direction. One solution adsorber 36 may be provided, or one solution adsorber 36 extending corresponding to the entire region in the x direction may be provided corresponding to all the organic thin film transistors 10 arranged in the x direction. Further, the solution adsorber 36 may be scanned in the y direction. Further, the organic thin film transistor 10 sandwiching the solution adsorber 36 may share the solution adsorber 36 (see the examples described later).

In this way, the organic semiconductor layer 18 is formed by drying the coating solution 38.
Here, according to the manufacturing method of the present invention, the organic semiconductor layer 18 having no film thickness unevenness (excellent film thickness uniformity) can be formed.

As shown in Patent Document 1 and Patent Document 2, in the formation of an organic semiconductor layer utilizing lyophilicity and liquid repellency with respect to a conventional coating solution, the coating is performed after forming a lyophilic treatment pattern on the liquid repellent surface. Apply the solution to form an organic semiconductor layer according to the lyophilic treatment pattern, or after forming the lyophilic layer, form a lyophobic layer over the entire surface, and etch the lyophilic layer by etching or the like. An organic semiconductor layer corresponding to the exposed lyophilic layer is formed by applying a coating solution.
In such a conventional method for forming an organic semiconductor layer, the solvent of the coating solution evaporates faster at the boundary surface between the lyophilic region and the lyophobic region than in the lyophilic region. It moves to the boundary surface between the region and the liquid repellent region. As a result of this movement, the coating solution is swelled at the boundary surface between the lyophilic region and the lyophobic region, and the organic semiconductor layer becomes thicker than the other regions in this swelled portion. .
As a result, the film thickness of the organic semiconductor layer of the organic thin film transistor varies. For example, when an organic thin film transistor array is formed, the transistor characteristics such as the on-current and the threshold voltage V _{th vary} among the organic thin film transistors. For example, it may be difficult to use various displays and sensors as switching devices.

On the other hand, in the manufacturing method of the present invention, after forming the insulator layer 28 to be the gate insulating layer 16 and patterning the first sacrificial film 30 thereon, the insulator layer 28 is etched to form the gate. The insulating layer 16 is formed, and the organic semiconductor layer 18 is formed by the coating solution 38 at the position where the first sacrificial film 30 is formed, that is, on the convex portion 16a protruding from the periphery.
Further, after the insulating layer 28 is etched to form the gate insulating layer 16, the surface other than the surface of the convex portion 16a including the side surface of the convex portion 16a has liquid repellency with respect to the coating solution 38. A liquid film 32 is formed (liquid repellent treatment is performed).
By forming the organic semiconductor layer 18 on such a convex portion 16a, the organic semiconductor layer 18 can be formed without a portion where the coating solution 38 swells, and thus the organic semiconductor layer 18 having a uniform thickness with no film thickness unevenness. Can be formed. Further, even when unnecessary crystals grow and precipitate in the coating solution, such crystals are highly likely to settle in a region other than the convex portion 16a. The decrease can also be suppressed. Furthermore, generally, when patterning is performed after the liquid repellent treatment is performed, the adhesion of the sacrificial film is deteriorated, and it becomes difficult to form a high-definition pattern. On the other hand, in the manufacturing method of the present invention, since the pattern formation of the first sacrificial film 30 is prior to the liquid repellent treatment, a normal semiconductor device manufacturing process can be used and a high-definition pattern can be formed. .
Therefore, according to the present invention, there is no variation in transistor characteristics such as the on-current and the threshold voltage _Vth between the organic thin-film transistors in which the organic thin-film transistor 10 having the organic semiconductor layer 18 having no film thickness unevenness is formed with high definition. An organic thin film transistor array that can be suitably used as a switching device for various displays and sensors can be obtained.

  In the present invention, the height of the protrusion 16a of the gate insulating layer 16 where the organic semiconductor layer 18 is formed (that is, the etching depth of the insulating layer 28 in the fourth step) is the size of the organic thin film transistor 10 to be formed. If the thickness of the organic semiconductor layer 18 to be formed, the application method of the coating solution 38, etc., the height at which an appropriate organic semiconductor layer 18 can be formed is appropriately determined by using experiments or simulations. Good.

Various shapes can be used for the cross-sectional shape of the convex portion 16 a of the gate insulating layer 16.
In addition, in the cross-sectional shape of the convex portion 16a, if the side surface where the source electrode 20 and the drain electrode 24, which will be described later, contact is an inverted slope (overhang), the source electrode 20 and the drain electrode 24 may be disconnected. . Therefore, this side surface is preferably upright or inclined at 90 ° or less with respect to the surface of the gate insulating layer 16 (the surface of the base material 12).

After the organic semiconductor layer 18 is formed in this way, the solution adsorbent 36 is removed as conceptually shown in FIG.
Next, the source electrode 20 is patterned from the surface of the gate insulating layer 16 over the organic semiconductor layer 18, and is further formed on the organic semiconductor layer 18 from the surface of the gate insulating layer 16 so as to face the source electrode 20. Then, the drain electrode 24 is patterned to produce the organic thin film transistor 10.

  Note that the formation of the source electrode 20 and the drain electrode 24 may remove the liquid repellent film 32 partially or entirely.

As the material for forming the source electrode 20 and the drain electrode 24, various known materials used in organic thin film transistors can be used. As an example, various materials exemplified for the gate electrode 14 are exemplified.
In addition, as a pattern forming method of the source electrode 20 and the drain electrode 24, various known methods corresponding to the forming material can be used. As an example, various methods exemplified for the gate electrode 14 are exemplified. Further, the source electrode 20 and the drain electrode 24 may be formed by patterning a charge injection layer (a hole injection layer in the case of a p-type semiconductor, an electron injection layer in the case of an n-type semiconductor) or the like. Good.

13 to 15 conceptually show another example of the organic thin film transistor of the present invention manufactured by the method of manufacturing an organic thin film transistor of the present invention.
13 to 15, (A) is a cross-sectional view, (B) is a plan view, and (A) is a cross-sectional view taken along line aa in (B). 13 to 15, the liquid repellent film 32 and the lyophilic film 34 are omitted, and the same members as those of the organic thin film transistor shown in FIG. 1 are denoted by the same reference numerals, and the description is mainly different. Repeat for the site.

In the organic thin film transistor 50 shown in FIG. 13, like the organic thin film transistor disclosed in Patent Document 2, an organic semiconductor layer 52 formed by a coating solution has a narrow width portion 52 a.
That is, in the first sacrificial film to be patterned, a region mainly serving as the organic semiconductor layer and a region serving as the narrow portion 52a are formed, and the narrow portion 52a is formed on the convex portion 54a of the gate insulating layer 54. A portion corresponding to is formed.

  As a result, a solution accumulation region mainly serving as an organic semiconductor layer and a solution narrowing region having a narrow width with respect to the solution accumulation region can be formed on the convex portion 54a, so that the coating solution is dried from the narrow portion 52a. Thus, the organic semiconductor layer 52 is formed therefrom. For this reason, according to this configuration, the crystal axis direction of the organic semiconductor layer 52 can be aligned without using the solution adsorbent 36, and an organic thin film transistor having excellent characteristics can be manufactured.

  The organic thin film transistor 58 shown in FIG. 14 has a configuration in which a gate insulating layer is divided into the above-described convex portion 16a and a lower planar planarizing layer 16b.

  When a flexible organic thin film transistor (array) using a plastic film as the base material 12 is bent, a crack may occur in the gate insulating layer and a short circuit failure may occur. In particular, in the organic thin film transistor of the present invention in which the organic semiconductor layer 18 is formed on the convex portion 16a of the gate insulating layer, stress concentrates on the step due to the convex portion 16a, and there is a possibility that a crack is generated here.

On the other hand, by forming the gate insulating layer into a two-layer structure in which the convex portion 16a and the lower planar planarizing layer 16b are divided, the organic thin film transistor is bent and a crack is generated in the planarizing layer 16b. However, this crack stops at the interface between the planarization layer 16b and the convex portion 16a.
Therefore, cracks can be prevented from occurring in the protrusions 16a on which the organic semiconductor layer 18 and the source electrode 20 and the drain electrode 24 are formed, and a short circuit failure due to bending of the thin film transistor can be prevented.
Note that such a two-layer gate insulating layer can be manufactured by, for example, forming a two-layer structure of an insulator layer to be a gate insulating layer.

  Further, in the organic thin film transistor 60 shown in FIG. 15, the gate insulating layer 62 is formed only at the formation position (formation region) of the organic semiconductor layer 18. Further, the organic thin film transistor 60 has a configuration in which the gate electrode 14 is embedded in the base material 12 and the surfaces of the gate electrode 14 and the base material 12 are uniform surfaces (same surface).

That is, in the manufacture of the organic thin film transistor 60 shown in FIG. 15, the etching of the insulator layer 28 in the fourth step is performed until the base material 12 is exposed except for the position where the first sacrificial film 30 is formed. Accordingly, the gate insulating layer 62 that is the position where the organic semiconductor layer 18 is formed protrudes from the peripheral substrate 12 (has a convex shape).
In the organic thin film transistor array having flexibility using a plastic film as the base material 12, when the gate insulating layer is formed on the entire surface of the base material 12, when the gate insulating layer is cracked when bent, This crack may propagate throughout. When such a crack occurs, a short circuit failure occurs in many organic thin film transistors. In addition, since the generation of defects is proportional to the area of the gate insulating layer, if the gate insulating layer is formed over the entire surface of the substrate 12, cracks are likely to occur.

  On the other hand, like the organic thin film transistor 60 shown in FIG. 15, the insulating layer 28 in the fourth step is etched until the base material 12 is exposed, and the gate insulating layer 62 is formed at the position where the organic semiconductor layer 18 is formed. By forming only in this manner, the propagation of cracks in the gate insulating layer between the organic thin film transistors 60 is prevented, and the occurrence of cracks in the gate insulating layer is also reduced. Can be prevented.

Further, like the organic thin film transistor 60 shown in FIG. 15, the gate electrode 14 is embedded in the base material 12, and the surface of the gate electrode 14 and the surface of the base material 12 are (substantially) uniform. The step at the end of the gate electrode 14 can be eliminated. Therefore, similarly, in a flexible organic thin film transistor (array) using a plastic film as the base material 12, it is possible to avoid stress concentration on the step when it is bent. The crack of the gate insulating layer 62 to be prevented can be prevented, and a short circuit failure due to the crack of the gate insulating layer can be prevented.
The effect of embedding the gate electrode 14 is the same when the gate insulating layer 16 (54) is formed on the entire surface of the substrate 12, as shown in FIGS.

As shown in FIG. 15, the gate electrode 14 having a structure embedded in the base material 12 is preferably formed as follows.
That is, first, a second sacrificial film having an opening at a position corresponding to the gate electrode 14 is pattern-formed on the surface of the substrate 12 (step A). This second sacrificial film is made of a known material, similar to the first sacrificial film, and may be formed by a known method.

Next, the surface of the substrate 12 is etched to a depth corresponding to the thickness of the gate electrode 14 (step B).
Various known methods can be used for etching the base material 12 in accordance with the material for forming the base material 12. Accordingly, as with the previous etching of the insulator layer 28, if the desired accuracy can be ensured, dry etching such as RIE or plasma etching, or wet etching using an etchant or organic solvent that dissolves the substrate 12 may be used.

Next, a material for the gate electrode 14 is formed on the surface of the second sacrificial film and the base material 12 (step C).
The gate electrode material may be formed by a known method according to a material to be formed, such as a vapor phase film forming method such as sputtering or vacuum evaporation. In addition, this film formation is preferably performed up to a thickness in which the surface of the base material 12 and the surface of the material formed on the etched portion of the base material 12 match (the etching depth and the film thickness are , Preferably match).

Finally, the second sacrificial film is removed to complete the gate electrode 14 embedded in the substrate 12 (step D).
The removal of the second sacrificial film may be performed by a known method corresponding to the type of the sacrificial film, similarly to the removal of the first sacrificial film.

  As mentioned above, although the manufacturing method of the organic thin-film transistor and the organic thin-film transistor of this invention were demonstrated in detail, this invention is not limited to the above-mentioned example, In the range which does not deviate from the summary of this invention, various improvement and change are performed. Of course, you may.

  Hereinafter, the specific example of this invention is given and the manufacturing method of an organic thin-film transistor and organic thin-film transistor of this invention are demonstrated in detail.

[Example]
The organic thin film transistor 60 conceptually shown in FIG. 16 (same configuration as the organic thin film transistor 60 of FIG. 15) was produced by the following procedure. Also in FIG. 16, (A) is a cross-sectional view, (B) is a plan view, and (A) is a cross-sectional view taken along the line aa of (B). In FIG. 16, the liquid repellent film and the lyophilic film are not shown, and in FIG. 16B, the base portion 36a of the solution adsorbent 36 is not shown.
Note that FIG. 16 (and FIG. 19) is merely a conceptual diagram for explaining the example (comparative example), and therefore the thickness of each part shown below, the dimensions shown in FIG. The relationship between the size of each part in and does not necessarily match.

  In this example, as shown conceptually in the plan view of FIG. 17, a total of 16 4 × 4 organic thin film transistors 60 are formed to form an organic thin film transistor array. In FIG. 17, the source electrode 20 and the drain electrode 24, and the base portion 36a of the solution adsorbent 36 are omitted.

<Preparation of base material>
Using a vacuum laminator (LM-20 × 20, manufactured by NPC) heated to 150 ° C., the strong adhesive surface of the double-sided adhesive tape (Sumitomo 3M, 4309) 72 is made from an alkali-free glass having a thickness of 0.7 mm. The glass carrier 70 was laminated.
Next, using the same vacuum laminator, a polyimide film (UPILEX-50S manufactured by Ube Industries, Ltd.) having a thickness of 50 μm was bonded as the base material 12 to the slightly adhesive surface of the double-sided adhesive tape 72 bonded to the glass carrier 70.

<Pattern formation of gate electrode 14 (first step)>
<< Pattern Formation of Second Sacrificial Film (Step A) >>
The surface of the substrate 12 (polyimide film) was subjected to ultraviolet ozone treatment. Thereafter, hexamethyldisilazane (HMDS: OAP manufactured by Tokyo Ohka Kogyo Co., Ltd.) was spin-coated on the surface of the substrate 12.
Subsequently, a pattern of a positive photoresist (TLOR-P003 HP manufactured by Tokyo Ohka Kogyo Co., Ltd.) was formed as a second sacrificial film by photolithography. This photolithography includes spin coating of photoresist, pre-baking, exposure with a mercury lamp i-line through a photomask, development with PEB, tetramethylammonium hydroxide (TMAH: NMD-3 2.38% manufactured by Tokyo Ohka Kogyo Co., Ltd.) Includes a washing process.
<< Etching of Upper Surface of Substrate 12 (Process B) >>
By etching using RIE using Ar gas and O ₂ gas, the gate electrode 14 forming portion (the portion where the photoresist is not formed) of the base material 12 is etched to form a 100 nm groove (trench) on the surface of the base material 12. Formed.
<< Film Formation of Gate Electrode Material (Step C) >>
On the surface of the photoresist and the substrate 12, aluminum (film thickness: 100 nm) to be the gate electrode 14 was formed by high-frequency magnetron sputtering using an aluminum target in an atmosphere with a vacuum degree of 1 Pa into which Ar gas was introduced.
<< Pattern Formation of Gate Electrode 14 (Process D) >>
The aluminum film-formed sample was immersed in acetone and then subjected to ultrasonic treatment to dissolve the photoresist. Subsequently, the sample was immersed in 2-propanol (IPA) and sonicated.
Finally, it is naturally dried so that the surface of the substrate 12 and the surface of the gate electrode 14 become a substantially uniform plane (there is no step between the surface of the substrate 12 and the surface of the gate electrode 14). The pattern was formed.

<Deposition of insulator layer (second step)>
Silicon nitride (thickness 0) is formed on the surface of the substrate 12 on which the gate electrode 14 is patterned by high-frequency magnetron sputtering using a silicon nitride target in an atmosphere with a vacuum degree of 0.1 Pa into which Ar gas and N ₂ gas are introduced. .3 μm), an insulator layer to be the gate insulating layer 62 was formed (see FIG. 3).

<First Sacrificial Film Pattern Formation (Third Step)>
After the surface of the insulator layer was subjected to ultraviolet ozone treatment, HMDS was spin-coated.
Subsequently, a pattern of a positive type photoresist (OFPR-800 manufactured by Tokyo Ohka Kogyo Co., Ltd.) was formed as a first sacrificial film by photolithography (see FIG. 4). This photolithography includes the steps of spin coating of photoresist, pre-baking, exposure with a mercury lamp i-line through a photomask, development with TMAH, washing with water, and post-baking.

<Insulator layer etching (fourth step)>
The portion of the insulator layer where the first sacrificial film was not formed was removed by RIE into which Ar gas, CF ₄ gas, and O ₂ gas were introduced until the surface of the substrate 12 was exposed. (See FIG. 5).

<Liquid repellency treatment for coating solution (fifth step)>
The sample in which the insulator layer was etched was immersed in a toluene solution (10 mmol · dm ⁻³ ) of octyltrichlorosilane (OTS). Next, ultrasonic treatment was performed while immersed in IPA.
Thus, the coating solution for forming the organic semiconductor layer 18 on the surface of the base material 12 exposed by etching and the side surface of the insulating layer to be the gate insulating layer 62 (the surface of the region where the insulating layer has been removed by etching). The toluene solution was a liquid repellent treatment (a liquid repellent film was formed on the surface of the region where the insulator layer was removed by etching. See FIG. 6).

<Removal of first sacrificial film (sixth step)>
The liquid-repellent-treated sample was immersed in acetone and then subjected to ultrasonic treatment to dissolve the first sacrificial film. Subsequently, the sample was immersed in IPA and sonicated. Finally, the first sacrificial film was removed by natural drying, and the gate insulating layer 62 was patterned. (See FIG. 7).

<Liquid treatment>
The sample from which the first sacrificial film was removed was immersed in a toluene solution (10 mmol · dm ⁻³ ) of (2-phenylethyl) trichlorosilane (β-PTS). Next, ultrasonic treatment was performed while immersed in IPA.
As a result, the surface of the gate insulating layer 62 (the portion not subjected to the liquid repellent treatment) was subjected to a lyophilic treatment (the surface of the gate insulating layer 62) with respect to the toluene solution, which is a coating solution for forming the organic semiconductor layer 18. A lyophilic film was formed (see FIG. 8).

<Application of Application Solution to be Organic Semiconductor Layer 18 (Seventh Step)>
As shown in FIG. 18, a member formed by forming a convex part having a width of 1 mm and a height of 3 mm as a solution adsorbent 36 on a base part 36a was made of silicone rubber made of polydimethylsiloxane (PDMS). Also in FIG. 18, (A) is a cross-sectional view, (B) is a plan view, and (A) is a cross-sectional view taken along the line aa of (B).

A sample in which the surface of the gate insulating layer 62 was subjected to lyophilic treatment was placed on a hot plate heated to 40 ° C. Next, the member having the prepared solution adsorbent 36 was placed on the surface of the substrate 12 with the solution adsorber 36 (convex portion) facing the substrate 12 as shown in FIG.
Subsequently, a toluene solution (0.2% by mass) of dioctylbenzothienobenzothiophene (C ₈ -BTBT) was dropped onto the entire surface of the sample as a coating solution for forming the organic semiconductor layer 18. Immediately thereafter, the Petri dish was placed upside down to cover the sample, exposing the sample to a saturated atmosphere of toluene vapor. After 1 hour, the Petri dish and the member having the solution adsorbent 36 were removed and dried for 12 hours to form an organic semiconductor layer 18 made of C ₈ -BTBT.
This step was performed in a glove box apparatus filled with dry nitrogen.

  Thereafter, the film thickness of each formed organic semiconductor layer 18 was measured with a stylus meter at nine points.

<Formation of Source Electrode 20 and Drain Electrode 24>
The sample on which the organic semiconductor layer 18 is formed is continuously vacuumed with tetrafluorotetracyanoquinodimethane (F ₄ -TCNQ film thickness 1 nm) and gold (film thickness 40 nm) through a nickel shadow mask. The source electrode 20 and the drain electrode 24 were formed by vapor deposition.
As a result, an organic thin film transistor array in which a total of 16 organic thin film transistors 60 as shown in FIG. 16 were produced by 4 × 4 as shown in FIG. 17 was produced.

[Comparative example]
In the following manner, an organic thin film transistor array in which a total of 16 organic thin film transistors 100 shown in FIG. 19A were formed in 4 × 4 as shown in FIG. 17 was produced. Note that also in FIG. 19A, a liquid repellent film 104 and a lyophilic film 106 which will be described later are omitted.

First, the laminated body formed by laminating | stacking the glass carrier 70 which consists of an alkali free glass, the double-sided adhesive tape 72, and the base material 12 made from a polyimide film similarly to the Example was produced.
An aluminum gate electrode 14 was patterned on the substrate 12 in the same manner as in the example.
Further, an insulator layer made of silicon nitride was formed on the surface of the substrate 12 in the same manner as in Example 1. In this example, this insulator layer becomes the gate insulating layer 102.

Next, the surface of the gate insulating layer 102 was subjected to ultraviolet ozone treatment.
A sample in which the surface of the gate insulating layer 102 was subjected to ultraviolet ozone treatment was dipped in a toluene solution of OTS and then ultrasonicated in a state of being dipped in IPA in the same manner as the liquid repellent treatment in the examples. Thus, the surface of the gate insulating layer 102 was subjected to a liquid repellent treatment with respect to the coating solution, and a liquid repellent film 104 was formed as conceptually shown in FIG.

As shown in FIG. 19C, a nickel shadow mask 108 having an opening corresponding to the organic semiconductor layer 18 is overlaid on the surface of the sample on which the liquid repellent film 104 is formed, and ultraviolet ozone treatment is performed. The liquid repellent film 104 at a position corresponding to the organic semiconductor layer 18 was removed.
After removing the shadow mask 108, the sample from which the liquid-repellent film 104 at the position corresponding to the organic semiconductor layer 18 was removed was immersed in a toluene solution of β-PTS in the same manner as the lyophilic treatment in the example. Next, this sample was subjected to ultrasonic treatment while being immersed in IPA. As a result, the surface of the gate insulating layer 102 at the opening of the shadow mask 108 is treated with a lyophilic solution with a toluene solution to form a lyophilic film 106 as conceptually shown in FIG. did.

Thereafter, the organic semiconductor layer 18 was formed using the coating solution and the solution adsorbent 36 in the same manner as in the example.
Subsequently, the film thickness of each formed organic semiconductor layer 18 was measured at 9 points with a stylus meter in the same manner as in the example.
Further, the source electrode 20 and the drain electrode 24 are formed by continuously vacuum-depositing F ₄ -TCNQ and gold, and the organic thin film transistor 100 as shown in FIG. 19A is formed as 4 × 4 as shown in FIG. A total of 16 organic thin film transistor arrays were produced.

[Evaluation test]
The field effect transistors (FETs) were evaluated by connecting the electrodes of the organic thin film transistor arrays of Examples and Comparative Examples prepared as described above and the terminals of a manual prober connected to Agilent Technologies 4155C. It was. Specifically, the field effect mobility was calculated by measuring the drain current-gate voltage (I _d -V _g ) characteristic.

Thereafter, the substrate 12 was peeled from the glass carrier 70 (the slightly adhesive surface of the double-sided adhesive tape 72). Next, the organic thin film transistor array was curved by winding it around a round bar having a radius of 1 cm with the back surface of the base material 12 (the non-formed surface of the transistor array) inside.
The organic thin film transistor array was removed from the round bar, and the organic thin film transistor array was placed on the glass plate with the substrate 12 facing downward, and the I _d -V _g characteristic was measured in the same manner as described above, and a gate short circuit occurred. The number of organic thin film transistors was examined.

[result]
The film thickness of the organic semiconductor layer 18 is
Examples have an average film thickness of 52 nm, a standard deviation of 10, a coefficient of variation of 0.19,
The comparative example had an average film thickness of 98 nm, a standard deviation of 73, and a coefficient of variation of 0.74.
The field effect mobility [cm ² · V ^-1 · s ^-1 ] is
Examples have an average of 1.2, a standard deviation of 0.5, a coefficient of variation of 0.42,
The comparative examples had an average of 0.9, a standard deviation of 1.3, and a coefficient of variation of 1.44.
Furthermore, the gate short circuit after bending is
Example is 1/16,
The comparative example was 6/16.

From the above results, the organic thin film transistor of the present invention is superior in film thickness uniformity of the organic semiconductor layer 18 as compared with the conventional organic thin film transistor, and the transistor characteristics of each organic thin film transistor when the organic thin film transistor array is formed are uniform. It turns out that it is excellent in property.
Moreover, according to this example, the gate short circuit after bending can also be reduced as compared with the conventional organic thin film transistor.
From the above results, the effects of the present invention are clear.

  It can be suitably used for manufacturing various devices using organic thin film transistors.

DESCRIPTION OF SYMBOLS 10, 50, 58, 60, 100 Organic thin-film transistor 12 Base material 14 Gate electrode 16, 16b, 54, 62, 102 Gate insulating layer 16a, 54a Protruding part 18, 52 Organic semiconductor layer 20 Source electrode 24 Drain electrode 28 Insulator layer 30 first sacrificial film 32,104 lyophobic film 34,106 lyophilic film 36 solution adsorbent 38 coating solution 70 glass carrier 72 double-sided tape 108 shadow mask

Claims (8)

A gate electrode formed on a base material; a gate insulating layer formed to cover the gate electrode; an organic semiconductor layer formed on the gate insulating layer; and a source formed on the organic semiconductor layer A method for producing an organic thin film transistor having an electrode and a drain electrode,
The organic semiconductor layer is formed using a coating solution containing an organic semiconductor material to be the organic semiconductor layer, and
A first step of patterning the gate electrode;
A second step of covering the gate electrode and forming an insulator layer to be the gate insulating layer;
A third step of patterning a first sacrificial film corresponding to the organic semiconductor layer on the insulator layer;
A fourth step of etching the insulator layer to form the gate insulating layer;
A fifth step of performing a liquid repellent treatment on the coating solution on at least one surface of the gate insulating layer and the base material;
A sixth step of removing the first sacrificial film; and
A method for producing an organic thin film transistor, comprising performing a seventh step of coating the coating solution on at least one surface of the gate insulating layer and the substrate.   2. The method for producing an organic thin film transistor according to claim 1, wherein a lyophilic treatment for the coating solution is performed at a position where the first sacrificial film is removed between the sixth step and the seventh step.   3. The method of manufacturing an organic thin film transistor according to claim 1, wherein in the seventh step, an adsorbent that adsorbs the coating solution is disposed on at least one of the gate insulating layer and the substrate. The first step is a step A of patterning a second sacrificial film on the substrate.
Etching the surface of the substrate to a depth corresponding to the thickness of the gate electrode, B
A step C of forming a material of the gate electrode on the surface of the second sacrificial film and the base material; and
The manufacturing method of the organic thin-film transistor of any one of Claims 1-3 including the process D which removes the said 2nd sacrificial film.   5. The method of manufacturing an organic thin film transistor according to claim 1, wherein, in the fourth step, etching is performed until the base material is exposed except in a region where the first sacrificial film is formed. . A gate electrode formed on a base material, a gate insulating layer formed so as to cover the gate electrode, and an organic semiconductor formed on the gate insulating layer using a coating solution containing an organic semiconductor material And a source electrode and a drain electrode formed on the organic semiconductor layer, and
The organic semiconductor layer is formed on the convex portion of the gate insulating layer protruding from the periphery, and further, including the side surface of the convex portion, except for the formation surface of the organic semiconductor layer, An organic thin film transistor characterized by being covered with a liquid repellent film.   The organic thin film transistor according to claim 6, wherein the base material has a concave portion, the gate electrode is inserted into the concave portion, and a surface of the gate electrode is uniform with a surface of the base material.   The organic semiconductor layer and the gate insulating layer have the same shape and size in the surface direction of the base material, and other than the formation region of the organic semiconductor layer and the gate insulating layer, and the formation region of the source electrode and the drain electrode The organic thin-film transistor according to claim 6 or 7, wherein a surface of the substrate is exposed.

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