JP2017183500A - Manufacturing method for organic thin film transistor, and organic thin film transistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for an organic thin film transistor, and an organic thin film transistor, in which the short-circuiting between source and drain electrodes can be prevented even if the distance between the source and drain electrodes is shortened.SOLUTION: A manufacturing method for an organic thin film transistor includes a step of forming a metal layer and an electrode formation step of forming source-drain electrodes by removing a part of the metal layer. In the formation of the source-drain electrodes, a part of the metal layer is removed by laser beam scanning, so that a first opening to separate between the source electrode and the drain electrode and a second opening which is in communication with the first opening and whose distance L2 between the source-drain electrodes is larger than the distance L1 of the first opening between the source-drain electrodes are formed. Thus, the problem is solved.SELECTED DRAWING: 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.

  Equipment that uses logic circuits such as thin film transistors (TFTs), RFIDs (Radio Frequency Identifiers, also referred to as RF tags) and memories used in liquid crystal displays and organic EL displays because they can be reduced in weight, cost, and flexibility. For example, an organic thin film transistor (organic TFT) having an organic semiconductor layer (organic semiconductor film) made of an organic semiconductor material is used.

  In recent years, it has been required to shorten the distance between the source electrode and the drain electrode, that is, the channel length due to the high integration of an electronic circuit using an organic thin film transistor. Also, a shorter channel length is advantageous in terms of mobility, that is, switching speed and responsiveness.

  In response to such demands, as a method of manufacturing an organic thin film transistor that achieves both fine processing accuracy and productivity, a metal layer is formed, and this metal layer is patterned by laser ablation to thereby form a source electrode and a drain. A method for forming an electrode or the like is known.

For example, in Patent Document 1, in a method for manufacturing an organic electronic device, when a conductive layer is patterned by forming a metal layer (conductive layer) and performing laser ablation, a pulse laser is used. A method for patterning a conductive layer using a single pulse is described.
In Patent Document 1, it is said that deterioration of the lower layer of the metal layer can be substantially eliminated by processing the metal layer using only a single laser pulse. Patent Document 1 also describes that processing is performed using a laser beam having a rectangular cross-sectional shape.

  Further, in Patent Document 2, in the manufacture of an organic thin film transistor, a metal layer is formed, and a part of the metal layer is removed by laser ablation, whereby a source electrode and a drain electrode, and a source electrode and a drain electrode are separated. It is described to define a channel length between. Patent Document 2 describes that the resolution of laser ablation is 2 to 4 μm.

Furthermore, in Patent Document 3, in the method for manufacturing an organic thin film solar cell, one or more of the upper electrode, the lower electrode, and the active layer are formed with a single laser wavelength, a rectangular beam shape, and a flat energy distribution. It is described that processing is performed by laser.
In Patent Document 3, by processing the upper electrode or the like with a laser having such a rectangular beam shape, the lower layer of the layer subjected to laser processing is prevented from being damaged by heat or the like by the laser, and It is said that efficient processing can be performed by reducing the overlapping rate (overlapping rate, overlap rate) when irradiating with overlapping laser beams.

JP 2013-118390 A Special table 2009-505427 JP 2014-60392 A

As described above, by forming the source electrode and the drain electrode by processing the metal layer by laser ablation, the source electrode and the drain electrode can be formed with high processing accuracy and good mass productivity.
However, according to the study of the present inventor, if the channel length is made ultrafine, for example, 5 μm or less in order to cope with the high integration of the electronic circuit, patterning defects are likely to occur in the overlapping portion of the laser beam, It becomes difficult to stably form appropriate source and drain electrodes.

As shown in Patent Document 1, processing of a metal layer by laser ablation is performed by using a pulse laser and scanning the metal layer with a laser beam.
As an example, as conceptually shown in FIG. 9, when the metal layer 100 is processed to form the source electrode 102 and the drain electrode 104, a laser beam Bz by a pulse laser is scanned in the horizontal direction in the figure. Then, the metal layer 100 is linearly removed by ablation with the laser beam Bz, and the source electrode 102 and the drain electrode 104 are formed.

In this case, the laser beam Bz is scanned on the surface of the metal layer 100 as conceptually shown in the upper part of FIG. 9 so as to appropriately remove the metal layer in the entire scanning direction. , And so as to overlap at the end in the scanning direction.
Also, as described in Patent Document 3, the laser beam Bz has a cross-sectional shape (cross-sectional shape in a direction orthogonal to the optical axis), that is, a beam spot shape, which is rectangular, thereby superimposing at the end in the scanning direction. It is possible to reduce the rate and perform efficient processing.

However, if the cross-sectional shape of the laser beam Bz is only rectangular, the intensity of the end of the laser beam Bz is weakened by diffraction, and the shape of the metal layer 100 removed by one pulse of the laser beam Bz is appropriate. It is no longer a rectangle.
As a result, as shown in the middle part of FIG. 9, the metal layer 100 cannot be properly removed at the end in the scanning direction, and the metal layer 100 remains between the source electrode 102 and the drain electrode 104, that is, in the channel portion. Patterning failure occurs, and the source electrode 102 and the drain electrode 104 are short-circuited.

This problem can be solved by increasing the overlay rate of the laser beam Bz at the end in the scanning direction on the metal layer 100.
However, when the overlapping ratio of the laser beam Bz at the end in the scanning direction is increased, the processing efficiency is lowered and the productivity is lowered.

In the top contact type organic thin film transistor, an organic semiconductor layer exists under the source electrode 102 and the drain electrode 104. Further, the overlapping region of the laser beam Bz results in the laser beam Bz being irradiated twice.
Therefore, in the overlapping region of the laser beam Bz, the organic semiconductor layer is deteriorated and the performance as a transistor is deteriorated. Therefore, if the overlapping region is increased, the amount of the organic semiconductor that deteriorates increases, and an organic thin film transistor having the intended performance cannot be manufactured.

Furthermore, in the manufacture of organic thin film transistors, a large number of organic thin film transistors are generally manufactured on a single substrate. Therefore, the processing of the metal layer 100 by the laser beam Bz is repeatedly performed while transporting the base material on which the metal layer 100 is formed, for example, in a direction orthogonal to the scanning direction of the laser beam Bz. Alternatively, the processing of the metal layer 100 by the laser beam Bz is performed by setting the scanning position of the laser beam Bz to the scanning direction of the laser beam Bz by the optical system of the laser beam Bz while the base material on which the metal layer 100 is formed is fixed. Repeatedly while moving in the orthogonal direction.
At this time, when the incident position of the laser beam Bz on the metal layer 100 fluctuates from the target position due to fluctuations in the optical system of the laser beam Bz and / or the transport system of the substrate, as shown in the lower part of FIG. The position of the metal layer 100 removed by the laser beam Bz is shifted in a direction orthogonal to the scanning direction of the laser beam Bz.
As a result, similarly, a patterning defect in which the metal layer 100 remains between the source electrode 102 and the drain electrode 104 occurs, and the source electrode 102 and the drain electrode 104 are short-circuited.

  An object of the present invention is to solve such a problem of the prior art, and in an organic thin film transistor, the gap between the source electrode and the drain electrode, that is, the channel length is made extremely fine for the purpose of high integration or the like. Even if it exists, it is providing the manufacturing method of an organic thin-film transistor and organic thin-film transistor which can prevent producing a short circuit etc. with a source electrode and a drain electrode, and can obtain a suitable product stably.

In order to achieve such an object, the method for producing an organic thin film transistor of the present invention is a method for producing an organic thin film transistor having a base material, a gate electrode, a gate insulating layer, an organic semiconductor layer, and a source electrode and a drain electrode. And
A step of forming a metal layer to be a source electrode and a drain electrode, and an electrode formation step of forming a source electrode and a drain electrode by removing a part of the metal layer, and
An electrode forming step of removing a part of the metal layer by scanning a laser beam to form a first opening separating the source electrode and the drain electrode; and
A plurality of provided in the direction perpendicular to the direction of separation between the source electrode and the drain electrode by the first opening, communicated with the first opening, and the distance L2 in the direction of separation between the source electrode and the drain electrode is And a step of forming a second opening that is longer than the distance L1 between the source electrode and the drain electrode of the first opening in the separation direction.

In such an organic thin film transistor manufacturing method of the present invention, in the step of forming the metal layer, the step of forming the second opening by patterning the metal layer is performed in the step of forming the metal layer. Is preferred.
The second opening is preferably formed by removing a part of the metal layer by scanning with a laser beam.
In the electrode formation step, it is preferable that the step of forming the first opening and the step of forming the second opening are performed in the same step.
In addition, it is preferable to form a charge injection layer between the organic semiconductor layer and the source and drain electrodes.
Further, it is preferable that the first opening is formed by a pulse laser, and the second opening overlaps an end portion in the scanning direction of the laser beam by the pulse laser that forms the first opening.
Moreover, it is preferable that the distance L1 in the separation direction between the source electrode and the drain electrode of the first opening is 5 μm or less.
Furthermore, the step of forming the metal layer is preferably performed after the organic semiconductor layer is formed.

The organic thin film transistor of the present invention is a base material, a gate electrode, a gate insulating layer, an organic semiconductor layer, and an organic thin film transistor having a source electrode and a drain electrode,
A gap between the source electrode and the drain electrode, a first opening separating the source electrode and the drain electrode, and
A plurality of provided in the direction perpendicular to the direction of separation between the source electrode and the drain electrode by the first opening, communicated with the first opening, and the distance L2 in the direction of separation between the source electrode and the drain electrode is Provided is an organic thin film transistor comprising a second opening that is longer than a distance L1 in the separation direction between a source electrode and a drain electrode of one opening.

In such an organic thin film transistor of the present invention, it is preferable to have a charge injection layer between the organic semiconductor layer and the source and drain electrodes.
Moreover, it is preferable that the distance L1 in the separation direction between the source electrode and the drain electrode of the first opening is 5 μm or less.
Moreover, it is preferable that an organic-semiconductor layer is located between a support body and a source electrode and a drain electrode.

  According to the present invention, even in the case where the gap between the source electrode and the drain electrode, that is, the channel length is made extremely fine for the purpose of high integration or the like, the organic thin film transistor causes a short circuit between the source electrode and the drain electrode. This can be prevented and a stable and appropriate product can be obtained.

It is the top view and sectional drawing which show notionally an example of the organic thin-film transistor of this invention. It is sectional drawing which shows notionally another example of the organic thin-film transistor of this invention. It is a conceptual sectional view for explaining an example of the manufacturing method of the organic thin-film transistor of the present invention. It is a conceptual top view for demonstrating an example of the manufacturing method of the organic thin-film transistor of this invention. It is a conceptual top view for demonstrating an example of the manufacturing method of the organic thin-film transistor of this invention. It is a conceptual top view for demonstrating an example of the manufacturing method of the organic thin-film transistor of this invention. It is a conceptual top view for demonstrating another example of the manufacturing method of the organic thin-film transistor of this invention. It is a conceptual diagram for demonstrating the Example of this invention. It is a top view which shows notionally an example of the conventional organic thin-film transistor.

  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.

FIG. 1 conceptually shows the position of the organic thin film transistor of the present invention.
In FIG. 1, the upper part is a plan view, and the lower part is a cross-sectional view taken along the line aa of the plan view. The plan view is a view of the organic thin film transistor viewed from the source electrode and drain electrode side in a direction orthogonal to a main surface of a base material to be described later. The cross-sectional view taken along the line aa is a cross-sectional view of the organic thin film transistor cut in the separation direction of the source electrode and the drain electrode, that is, in the channel length direction.

  As shown in FIG. 1, the organic thin film transistor 10 includes a base material 12, a gate electrode 14, a gate insulating layer 16, an organic semiconductor layer 18, a source electrode 24 and a drain electrode 26.

The organic thin film transistor 10 of the present invention is basically known in the art except that it is characterized by the shape of the gap between the source electrode 24 and the drain electrode 26, that is, the shape of the facing side of the source electrode 24 and the drain electrode 26. It is a thin film transistor.
Therefore, the size, shape, thickness, and the like of each part such as the gate electrode 14, the gate insulating layer 16, the organic semiconductor layer 18, the source electrode 24, and the drain electrode 26 are determined according to the formation material of each part and the organic thin film transistor 10 to be manufactured. What is necessary is just to determine suitably according to a magnitude | size, the arrangement | sequence of the organic thin-film transistor 10, the performance requested | required of the organic thin-film transistor 10, etc. similarly to a well-known organic thin-film transistor (organic thin-film transistor array).

Further, the organic thin film transistor 10 in the illustrated example is a bottom gate-top contact type, but the present invention is not limited to this.
That is, the organic thin film transistor and the method for manufacturing the organic thin film transistor of the present invention can be used for any of a top gate-top contact type, a bottom gate-bottom contact type, and a top gate-bottom contact type.
In particular, since the organic semiconductor layer is located on the substrate side with respect to the source electrode and the drain electrode, it is difficult to form the source electrode and the drain electrode by photolithography, and laser beam ablation is used for forming the source electrode and the drain electrode. The top contact type organic thin film transistor is preferably used in that processing is preferably used.

In the organic thin film transistor 10 of the present invention, the base material 12 can use various sheet-like materials made of various materials used as a base material (substrate) in the organic thin film transistor.
Specific examples include sheet-like materials (plate-like materials and film-like materials) made of various materials such as glass, metals having an insulating layer such as an oxide layer formed on the surface, ceramics, and resins.

Among these, a flexible film-like substrate is preferably used in that a flexible organic thin film transistor can be formed. Specifically, resin films made of various resin materials are suitably used as the base material 12.
Specific examples of the resin film material used for the substrate 12 include polyester resin, methacrylic resin, methacrylic acid-maleic acid copolymer, polystyrene resin, fluorine resin, polyimide, fluorinated polyimide resin, polyamide resin, and polyamide. Imide resin, polyether imide resin, cellulose acylate resin, polyurethane resin, polyether ether ketone resin, polycarbonate resin, alicyclic polyolefin resin, polyarylate resin, polyether sulfone resin, polysulfone resin, cycloolefin solvent, fluorene ring Examples thereof include thermoplastic resins such as modified polycarbonate resins, alicyclic modified polycarbonate resins, fluorene ring modified polyester resins, and acryloyl compounds.

  In the present invention, the substrate 12 may have a multilayer structure such as a structure in which a plurality of resin films are bonded together.

A gate electrode 14 is formed on one surface of the substrate 12.
The gate electrode 14 is also a known gate electrode used in organic thin film transistors.
Accordingly, as the material for forming the gate electrode 14, various known materials that are used as gate insulating layers in organic thin film transistors can be used. Specific examples of the material for forming the gate electrode 14 include metals such as aluminum, chromium, copper, molybdenum, tungsten, gold, silver, alloys, transparent conductive oxides (TCO) such as indium tin oxide (ITO), Examples thereof include conductive polymers such as polyethylenedioxythiophene-polystyrene sulfonic acid (PEDOT-PSS).
Further, the gate electrode 14 may have a stacked structure in which layers made of these materials are stacked.

  A gate insulating layer 16 is formed on the gate electrode 14. In the present specification, “upper” indicates the side opposite to the base material 12, and “lower” indicates the side of the base material 12.

The gate insulating layer 16 is also a known gate insulating layer used in organic thin film transistors.
Accordingly, as the material for forming the gate insulating layer 16, various known materials that are used as the gate insulating layer in the organic thin film transistor can be used. Specific examples of the material for forming the gate insulating layer 16 include silicon oxide (SiO _x ), magnesium oxide, aluminum oxide (alumina), titanium oxide, germanium oxide, yttrium oxide, zirconium oxide, niobium oxide, and tantalum oxide. Metal oxides, metal nitrides such as silicon nitride (Si _x N _y ), metal nitride oxides (metal oxynitride) such as silicon nitride oxide (SiO _x N _y ), and inorganic materials such as diamond-like carbon (DLC) And various polymer materials.
The gate insulating layer 16 may have a stacked structure in which layers made of these materials are stacked.

An organic semiconductor layer 18 is formed on the gate insulating layer 16.
The organic semiconductor layer 18 is also an organic semiconductor layer made of a known organic semiconductor material used in organic thin film transistors. The organic semiconductor layer 18 may be a p-type organic semiconductor layer or an n-type organic semiconductor layer.
Therefore, as the organic semiconductor material, various known materials that are used for the organic semiconductor layer in the manufacture of the organic thin film transistor can be suitably used. 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, Naphthalene tetracarboxylic acid diimide (NTCDI) such as 6,12-dioxaanthanthrene (perixanthenoxanthene) derivative, N, N′-bis (cyclohexyl) naphthalene-1,4,5,8-bis (dicarboximide) ) Invitation Perylenetetracarboxylic acid diimide (PTCDI) derivative, polythiophene derivative, poly (2,5-bis (thiophen-2-yl) thieno [3,2-b] thiophene) (PBTTT) derivative, tetracyanoquinodimethane ( Examples include TCNQ) derivatives, oligothiophenes, phthalocyanines, fullerenes and the like.

A source electrode 24 and a drain electrode 26 are formed on the organic semiconductor layer 18.
The source electrode 24 and the drain electrode 26 are basically known source and drain electrodes used in organic thin film transistors, except that they are characterized in shape.
Therefore, as the material for forming the source electrode 24 and the drain electrode 26, various known materials that are used as the source electrode 24 and the drain electrode 26 in the organic thin film transistor can be used as in the case of each layer. Specific examples of the forming material include various materials exemplified for the gate electrode 14 described above.

As described above, the organic thin film transistor 10 of the present invention has the shape of the gap between the source electrode 24 and the drain electrode 26, that is, the shape of the side facing the source electrode 24 and the drain electrode 26, that is, the shape of the channel. Basically, it is a known organic thin film transistor except that it has characteristics.
As shown in FIG. 1, in the organic thin film transistor 10 of the present invention, the gap between the source electrode 24 and the drain electrode 26 is formed by two openings having different distances in the facing direction between the source electrode 24 and the drain electrode 26.

In the following description, for convenience, “the direction in which the source electrode 24 and the drain electrode 26 are separated”, that is, the so-called channel length direction is also referred to as “channel length direction”. In the following description, for convenience, a direction orthogonal to the “channel length direction”, that is, a so-called channel width direction is also referred to as a “channel width direction”.
Accordingly, the channel length direction is the horizontal direction in FIG. 1, and the channel width direction is the vertical direction in the plan view of the upper stage of FIG. 1 and the direction perpendicular to the paper surface in the cross-sectional view of the lower stage of FIG.

Specifically, in the organic thin film transistor 10, a gap between the source electrode 24 and the drain electrode 26, that is, a channel, a first opening 30 that separates the source electrode 24 and the drain electrode 26 corresponding to the entire region in the channel width direction, A plurality (three in the illustrated example) of the second openings 32 that communicate with the first opening 30 are formed apart from each other in the channel width direction.
In the organic thin film transistor 10, the distance L2 of the second opening 32 in the channel length direction is longer than the distance L1 of the first opening 30 in the channel length direction. That is, in the organic thin film transistor 10, the distance L <b> 2 between the source electrode 24 and the drain electrode 26 separated by the second opening 32 with respect to the distance L <b> 1 between the source electrode 24 and the drain electrode 26 separated by the first opening 30. Is long.
The organic thin film transistor 10 of the present invention is configured such that the gap between the source electrode 24 and the drain electrode 26 is constituted by a plurality of openings having different distances in the channel length direction, so that the source electrode 24 and the drain electrode 26 are prevented from being short-circuited, and an appropriate organic thin film transistor can be stably obtained.

As described above, in order to cope with high integration and the like, it is required to narrow the distance between the source electrode 24 and the drain electrode 26, that is, the channel length. On the other hand, as a manufacturing method that can achieve both processing accuracy and productivity, a metal layer to be the source electrode 24 and the drain electrode 26 is formed, and the source electrode 24 and the drain electrode 26 are formed by patterning the metal layer by laser ablation. How to do is known.
As described above, processing of electrodes by laser ablation is performed by scanning a laser beam using a pulse laser. In addition, in the processing of electrodes by laser ablation, a pulsed laser beam is overlapped in the scanning direction on the processing surface in order to perform appropriate processing, but by forming the cross-sectional shape of the laser beam, that is, the beam spot shape into a rectangle. In addition, it is possible to reduce the overlay rate for properly forming the gap between the source electrode 24 and the drain electrode 26 and to improve the production efficiency.
However, in the conventional organic thin film transistor, when the distance between the source electrode 24 and the drain electrode 26, that is, the channel length is narrowed and extremely miniaturized, processing defects at the scanning direction end of the laser beam (beam spot) and / or laser As described above, the patterning failure occurs due to the beam scanning, the substrate conveyance fluctuation, and the like, and the source electrode 24 and the drain electrode 26 are short-circuited (see FIG. 9). ).

On the other hand, the organic thin film transistor 10 of the present invention includes a first opening 30 that separates the source electrode 24 and the drain electrode 26 from the source electrode 24 and the drain electrode 26 corresponding to the entire region in the channel width direction. A plurality of second openings 32 that are spaced apart in the channel width direction and communicate with the first opening 30 and that have a distance L2 in the channel length direction that is longer than the distance L1 of the first opening 30 in the channel length direction. To do.
Therefore, as will be described in detail later, the first opening 30 is formed even if the distance L1 in the channel length direction of the first opening 30 that mainly becomes the gap between the source electrode 24 and the drain electrode 26, that is, the channel, is shortened and extremely fine. Since the second opening 32 having a long distance L2 in the channel length direction is provided at the end of the laser beam in the scanning direction, the source electrode is formed by the second opening 32 at the end of the laser beam forming the first opening 30 in the scanning direction. 24 and the drain electrode 26 can be separated. Therefore, according to the present invention, it is possible to prevent a short circuit between the source electrode 24 and the drain electrode 26 due to a patterning defect and to stably obtain an appropriate organic thin film transistor 10.

In the organic thin film transistor 10 of the present invention, the distance L1 in the channel length direction of the first opening 30, that is, the gap between the source electrode 24 and the drain electrode 26, that is, the channel length in the organic thin film transistor 10, is the size of the organic thin film transistor 10. 10 may be set as appropriate in accordance with the degree of integration required for the device using 10 and the characteristics required for the organic thin film transistor 10.
According to the study of the present inventor, the first point is that the high integration and the short-circuit between the source electrode 24 and the drain electrode 26 due to the miniaturization of the channel length are likely to occur, that is, the effect of the present invention is more manifested. The distance L1 in the channel length direction of the opening 30 is preferably 5 μm or less, more preferably 0.05 to 5 μm, and particularly preferably 0.1 to 2 μm.

The distance L2 of the second opening 32 in the channel length direction, that is, the gap between the source electrode 24 and the drain electrode 26 by the second opening 32 only needs to be longer than the distance L1 of the first opening 30 in the channel length direction. What is necessary is just to set suitably according to the magnitude | size of the organic thin-film transistor 10, the characteristic requested | required of the organic thin-film transistor 10, etc.
According to the study of the present inventor, the organic thin film transistor 10 can be reduced in size, which can reliably communicate with the first opening 30 and prevent a short circuit between the source electrode 24 and the drain electrode 26. The distance L2 in the channel length direction of the second opening 32 is preferably 1 to 600 μm, and more preferably 5 to 60 μm, in that the current density distribution can be made uniform.

Similarly, the size w of the second opening 32 in the channel width direction may be appropriately set according to the size of the organic thin film transistor 10, characteristics required for the organic thin film transistor 10, and the like.
According to the study of the present inventor, the second opening 32 can be reliably communicated with the first opening 30 to prevent a short circuit between the source electrode 24 and the drain electrode 26 and the organic thin film transistor 10 can be reduced in size. The size w in the channel width direction is preferably 50% to 50 μm of the distance L1 of the first opening 30 in the channel length direction, and more preferably 10 μm, which is the same as the distance L1.

Here, in the second opening 32, the distance L <b> 2 in the channel length direction, that is, the distance between the source electrode 24 and the drain electrode 26 is wider than the distance L <b> 1 that is the basic channel length of the organic thin film transistor 10. For this reason, the region where the second opening 32 is formed has lower characteristics as a transistor than the region where only the first opening 30 is formed. When the distance L2 is long, the region where the second opening 32 is formed functions as a transistor. In some cases, it may not be possible.
In consideration of this point, in the organic thin film transistor 10 of the present invention, the total of the sizes w of all the second openings 32 in the channel width direction (the total of the three sizes w in the illustrated example) is It is preferably 50% or less of the channel width, and more preferably 20% or less.

In FIG. 2, the conceptual diagram of another example of the organic thin-film transistor of this invention is shown.
2 is a cross-sectional view similar to the cross-sectional view in the lower part of FIG. Moreover, since the organic thin-film transistor 40 shown in FIG. 2 uses many the same members as the organic thin-film transistor 10 shown in FIG. 1, the same code | symbol is attached | subjected to the same site | part and the following description mainly performs a different site | part.

The organic thin film transistor 40 shown in FIG. 2 has a charge injection layer 42 between the organic semiconductor layer 18 and the source electrode 24 and the drain electrode 26.
As is well known, the charge injection layer 42 provided in the organic thin film transistor 40 is a layer for injecting charges (electrons or holes) into the organic semiconductor layer 18. By having such a charge injection layer, the organic thin film transistor 40 can improve the charge injection efficiency and improve the mobility. In addition, by having the charge injection layer 42 between the organic semiconductor layer 18 and the source electrode 24 and the drain electrode 26, the workability of the metal layer by a laser beam, which will be described later, is improved, and the metal layer is more reliably formed. A short circuit between the source electrode 24 and the drain electrode 26 due to the patterning failure can be prevented.

Various materials can be used as the material for forming the charge injection layer 42 as long as it has a function of injecting charges (holes and electrons) into the organic semiconductor layer 18.
As an example, when the organic semiconductor is a p-type semiconductor, that is, when the organic thin film transistor 10 is a p-type organic thin film transistor, the material for forming the charge injection layer 42 has a hole transporting property (hole injection function). Various materials can be used.
Materials having hole transporting properties include triarylamine compounds, benzidine compounds, pyrazoline compounds, styrylamine compounds, hydrazone compounds, triphenylmethane compounds, carbazole compounds, polysilane compounds, thiophene compounds, phthalocyanine compounds, cyanine compounds, merocyanine compounds , Oxonol compounds, polyamine compounds, indole compounds, pyrrole compounds, pyrazole compounds, polyarylene compounds, condensed aromatic carbocyclic compounds (naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives), Examples thereof include a metal complex having a nitrogen heterocyclic compound as a ligand.
Specifically, in the low molecular weight material, pentacene and a derivative of pentacene, N, N′-bis (3-methylphenyl)-(1,1′-biphenyl) -4,4′-diamine (TPD), 4, Aromatic diamine compounds such as 4′-bis [N- (naphthyl) -N-phenyl-amino] biphenyl (α-NPD), oxazole, oxadiazole, triazole, imidazole, imidazolone, stilbene derivative, pyrazoline derivative, tetrahydroimidazole , Polyarylalkane, butadiene, 4,4 ′, 4 ″ -tris (N- (3-methylphenyl) N-phenylamino) triphenylamine (m-MTDATA), porphine, tetraphenylporphine copper, phthalocyanine, copper phthalocyanine , Porphyrin compounds such as titanium phthalocyanine oxide , Triazole derivatives, oxazizazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, annealed amine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, silazane derivatives, etc. Examples of the polymer material include polymers such as phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, and diacetylene, and derivatives thereof.
An inorganic material can also be used as the material having a hole transporting property. Specifically, vanadium oxide, chromium oxide, chromium oxide copper, manganese oxide, cobalt oxide, nickel oxide, copper oxide, gallium copper oxide, molybdenum oxide, indium copper oxide, indium silver oxide, tungsten oxide, iridium oxide, iodide Examples include copper.
The material having hole transporting properties is not limited to these, and various materials can be used as long as the material has a lower ionization potential than the organic compound used as the p-type organic semiconductor layer.

On the other hand, when the organic semiconductor is an n-type semiconductor, that is, when the organic thin film transistor 10 is an n-type organic thin film transistor, various materials having an electron transport property (electron injection function) can be used as a material for forming the charge injection layer 42. Material is available.
Materials having electron transporting properties include condensed aromatic carbocyclic compounds (naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives), nitrogen atoms, oxygen atoms, and sulfur atoms. -7-membered heterocyclic compounds (eg, pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, quinoxaline, quinazoline, phthalazine, cinnoline, isoquinoline, pteridine, acridine, phenazine, phenanthroline, tetrazole, pyrazole, imidazole, thiazole, oxazole, Indazole, benzimidazole, benzotriazole, benzoxazole, benzothiazole, carbazole, purine, triazolopyridazine, triazolopyrimidine Tetrazaindene, oxadiazole, imidazopyridine, pyralidine, pyrrolopyridine, thiadiazolopyridine, dibenzazepine, tribenzazepine, etc.), polyarylene compounds, fluorene compounds, cyclopentadiene compounds, silyl compounds, nitrogen-containing heterocyclic compounds Examples include a metal complex having a ligand.
Fullerenes and fullerene derivatives can also be used as materials having an electron transporting property. Specific examples of fullerene derivatives include C ₆₀ , phenyl-C ₆₁ -butyric acid methyl ester (fullerene derivatives referred to as PCBM, [60] PCBM, or PC ₆₁ BM in literatures), C ₇₀ , phenyl-C ₇₁ —. (in many literatures, PCBM, [70] PCBM or PC ₇₁ BM fullerene derivative called,) butyric acid methyl ester, and advanced functional Materials Vol. 19, described on pages 779 to 788 (2009) Examples include fullerene derivatives, fullerene derivatives SIMEF described in Journal of the American Chemical Society, vol. 131, page 16048 (2009), and the like.
An inorganic material can also be used as the material having an electron transporting property. Specific examples include lithium oxide, magnesium oxide, aluminum oxide, calcium oxide, titanium oxide, zinc oxide, strontium oxide, niobium oxide, ruthenium oxide, indium oxide, zinc oxide, barium oxide and the like. Alkali metal or alkaline earth metal fluorides, oxides, carbonates, and the like can also be used.
Note that the material having an electron transporting property is not limited to these, and various materials can be used as long as the material has an electron affinity higher than that of the organic compound used as the n-type organic semiconductor layer.

Hereafter, the manufacturing method of the organic thin-film transistor of this invention is demonstrated by demonstrating the manufacturing method of the organic thin-film transistor shown in FIG.
First, as conceptually shown in FIG. 3, the gate electrode 14 is formed on the substrate 12, the gate insulating layer 16 is formed on the gate electrode 14, and the organic semiconductor layer 18 is formed on the gate insulating layer 16. A laminated body is formed. FIG. 3 is a cross-sectional view similar to the lower part of FIG.
The formation of the gate electrode 14, the gate insulating layer 16, and the organic semiconductor layer 18 may be performed by any known method used in the manufacture of organic thin film transistors (organic semiconductor elements).
When the organic thin film transistor 40 shown in FIG. 2 is manufactured, a charge injection layer 42 is further formed on the organic semiconductor layer 18. The charge injection layer 42 may also be formed by a known method used in the manufacture of organic thin film transistors.

Next, as shown in FIGS. 3 and 4, a metal layer 50 to be the source electrode 24 and the drain electrode 26 is formed on the organic semiconductor layer 18 (charge injection layer 42).
4 to 6 are plan views. 4 to 6, the channel length direction is the vertical direction in the figure, and the channel width direction is the horizontal direction in the figure.

Here, in this manufacturing method, the formation of the metal layer 50 is performed by patterning, so that when the metal layer 50 is formed, the gap between the source electrode 24 and the drain electrode 26, that is, a part of the channel. An opening 32 is formed.
The metal layer 50 may be formed by a known method according to the material for forming the metal layer 50, such as a vapor deposition method such as vacuum deposition or sputtering, or a wet deposition method by coating or printing.
The formation of the second opening 32 by patterning when forming the metal layer 50 may be performed by a known method such as a method using a shadow mask.

Next, as conceptually shown in FIG. 4, the metal layer 50 is scanned in the channel width direction (lateral direction in the figure) by the laser beam B by the pulse laser. Thereby, a part of the metal layer 50 is removed by laser ablation, and the first opening 30 is formed and the source electrode 24 and the drain electrode 26 are formed, as conceptually shown in FIG. A thin film transistor 10 is manufactured.
In the manufacture of organic thin film transistors, a large number of organic thin film transistors are generally manufactured on one base 12. Therefore, the first opening 30 is formed a plurality of times, for example, while continuously or intermittently transporting the base material 12 on which the metal layer 50 is formed in a direction orthogonal to the scanning direction of the laser beam B. May be. Alternatively, the first opening 30 is formed by, for example, scanning the laser beam B with the scanning position of the laser beam B by the optical system of the laser beam B with the base material 12 on which the metal layer 50 is formed fixed. A plurality of times may be performed while continuously or intermittently moving in a direction orthogonal to the direction. When the substrate 12 is intermittently conveyed or the scanning position of the laser beam B is intermittently moved, the scanning of the laser beam B is usually performed when the conveyance or movement is stopped. This also applies to the formation of the second opening 32 using a laser beam, which will be described later, and the formation of the first opening 30 and the second opening 32 using the laser beam Ba.

For example, the first opening 30 is formed by using a long laser beam B having a rectangular cross-sectional shape as shown by a broken line in FIG. This is done by scanning the metal layer 50 in the direction indicated by the arrow in the figure. The cross-sectional shape of the laser beam B is a cross-sectional shape in a direction perpendicular to the optical axis of the laser beam B, that is, the shape of a beam spot.
Further, the scanning of the laser beam B is performed in a pulsed manner as indicated by a broken line in FIG. 4 so as to appropriately remove the metal layer 50 in the channel width direction (the lateral direction in FIGS. 4 and 5), that is, in the entire scanning direction. The pulsed laser beam B (beam spot) by the laser is slightly overlapped at the end in the scanning direction on the surface of the metal layer 50. As described above, by using the laser beam B formed into a rectangular shape, the superposition ratio of the laser beam B can be reduced and the production efficiency can be improved.
Further, the first opening 30 is formed so that the end portion in the scanning direction of the laser beam B by the pulse laser overlaps the second opening 32 formed in advance on the surface of the metal layer 50.

As described above, in the method for manufacturing the organic thin film transistor of the present invention, the source electrode 24 and the drain electrode 26 are formed mainly by forming a gap, that is, a channel between both electrodes in the metal layer 50 to be the source electrode 24 and the drain electrode 26. This is done by forming the first opening 30 and the second opening 32 in which the distance L2 in the channel length direction is longer than the distance L1 of the first opening in the channel length direction.
According to the manufacturing method of the present invention as described above, the intensity of the end portion in the scanning direction of the laser beam B forming the first opening 30 is reduced due to diffraction and the like, as indicated by a two-dot chain line in FIG. Even if a poor patterning occurs, the source electrode 24 and the drain electrode 26 can be reliably separated by forming the second opening 32.
Further, even if the scanning of the laser beam B and / or the conveyance of the base material 12 is changed, the scanning position of the laser beam B on the metal layer 50 is changed in the direction orthogonal to the scanning direction, the second opening 32. By forming, the source electrode 24 and the drain electrode 26 can be reliably separated as conceptually shown in FIG.
Therefore, according to the present invention, even when the channel length is extremely reduced to 5 μm or less, a short circuit between the source electrode 24 and the drain electrode 26 is prevented, and an appropriate organic thin film transistor 10 is stably formed. Can be obtained.

The cross-sectional shape of the laser beam B may be formed by a known method.
As an example, a method using a mask and / or slit for a laser beam, a method using a rectangular core fiber, a method using a cylindrical lens, a method using a hologram, a method using a waveguide, and a process capable of forming a laser beam One or more methods selected from methods using a lens subjected to the above are exemplified.

In the manufacturing method of the present invention, the end of the pulsed laser beam B forming the first opening 30 in the scanning direction on the metal layer 50 has a sufficient amount in the scanning direction (channel width direction) in advance. When overlapping with the formed second opening 32, the end portions in the scanning direction of the laser beams B do not need to overlap.
This also applies to the manufacturing method in which the second opening 32 is formed by laser ablation described below.

In the manufacturing method shown in FIGS. 3 to 6, the second opening 32 is formed when the metal layer 50 is formed by patterning to form the metal layer 50. On the other hand, in another aspect of the manufacturing method of the present invention, the second opening 32 is also formed by laser ablation.
That is, similarly to the above, the gate electrode 14, the gate insulating layer 16, and the organic semiconductor layer 18 are formed on the base material 12.
Further, a metal layer is formed on the entire surface of the organic semiconductor layer 18 without patterning (see FIG. 7). The metal layer may be formed in the same manner as described above.
Next, by scanning the metal layer with a laser beam, a part of the metal layer is removed by laser ablation, and the second opening 32 is formed in the metal layer as in FIG. The metal layer may be processed in the same manner as a known metal layer by laser ablation using a laser beam.
After this, as in the previous manufacturing method, as shown in FIG. 4, the metal layer is scanned in the channel width direction by the laser beam B formed in a rectangular shape to form the first opening 30, and FIG. As shown, the source electrode 24 and the drain electrode 26 are formed, and the organic thin film transistor 10 is fabricated.

  In the above example, the first opening 30 and the second opening 32 are formed in separate steps. On the other hand, in another aspect of the manufacturing method of the present invention, the source electrode 24 and the drain electrode 26 are formed by forming the first opening 30 and the second opening 32 in the same process, and the organic thin film transistor 10 is formed. Is made.

Also in this method, the gate electrode 14, the gate insulating layer 16, and the organic semiconductor layer 18 are formed on the substrate 12 in the same manner as described above.
Further, as conceptually shown in the upper part of FIG. 7, the metal layer 54 is formed on the entire surface of the organic semiconductor layer 18 without patterning. The formation of the metal layer 54 may be performed in the same manner as described above.

Next, as shown by a broken line in the upper part of FIG. 7, the metal layer 54 is formed, for example, in the drawing by using a laser beam Ba having a cross-sectional shape shaped according to the first opening 30 and the second opening 32 using a pulse laser. Scan in the direction indicated by the arrow. That is, the laser beam Ba has regions of the same shape as the second opening 32 on the surface of the metal layer 54 separated by the same distance in the channel width direction, and the two regions are formed in the first opening. It has a substantially H-shaped cross-section connected by a region having the same width as 30 distances L1 in the channel length direction.
An area corresponding to the second opening 32 at the scanning direction end of the pulsed laser beam Ba, with the laser beam Ba matching the longitudinal direction of the area corresponding to the first opening 30 and the scanning direction. And the metal layer 54 is scanned.
By scanning with the laser beam Ba, as shown conceptually in the lower part of FIG. 7, a part of the metal layer 54 is removed by laser ablation to form the first opening 30 and the second opening 32. The electrode 24 and the drain electrode 26 are formed, and the organic thin film transistor 10 is produced.

In the example shown in FIG. 7, both end regions in the scanning direction of the pulsed laser beam Ba on the metal layer 54 have the same shape as the second opening 32, and the second opening 32 is formed on the metal layer 54. Although both ends of the corresponding laser beam Ba in the scanning direction are completely overlapped, the present invention is not limited to this.
For example, the second opening 32 is formed by making the size in the scanning direction (channel width direction) of the regions at both ends in the scanning direction of the laser beam Ba smaller than the size w of the second opening 32 in the channel width direction. The laser beam Ba may partially overlap in the region.
Alternatively, the laser beam is not substantially H-shaped but substantially T-shaped, and a long region corresponding to the first opening 30 is formed on the metal layer 54 for each pulsed laser beam (beam spot). Similarly, by forming the first opening 30 and the second opening 32 by scanning the laser beam so as to overlap with the region corresponding to the second opening 32 of the adjacent laser beam, the source electrode 24 and the drain electrode 26 are formed. The organic thin film transistor 10 may be manufactured.

  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.

<Preparation of base material 12>
A 2.5 × 2.5 cm laminated product obtained by laminating a removable film (Panacku ETA100A, manufactured by Panac Co., Ltd.) on a polyimide film (Ube Industries Co., Ltd., Upilex-50S) as the base material 12. Prepared.
This laminated product is 2.5 × in a vacuum laminator (manufactured by NPC, LM-20 × 20) heated to 150 ° C. using a double-sided adhesive tape (manufactured by 3M, 4390). Laminated to a 2.5 cm glass carrier. The bonding was performed so that the polyimide film was on the upper surface.

<Formation of Gate Electrode 14>
A gate electrode 14 was produced by depositing an aluminum layer having a thickness of 100 nm on the surface of the substrate 12 (polyimide film) by high-frequency magnetron sputtering using an aluminum target in an atmosphere of 1 Pa pressure into which Ar gas was introduced. .

<Formation of Gate Insulating Layer 16>
PGMEA (propylene glycol-1-monomethyl ether-2-acetate) solution containing 20% by mass of poly (4-vinylphenol) (manufactured by SIGMA-ALDRICH, 436216), poly (melamine-co-formaldehyde) (SIGMA- A coating solution was prepared by mixing a PGMEA solution containing 10% by mass of ALDRICH, 418560) at a volume ratio of 1: 2.
This coating solution was applied onto the gate electrode 14 by spin coating. Subsequently, the gate insulating layer 16 having a thickness of 0.5 μm was formed by heating at 150 ° C. for 1 hour on a hot plate in a dry nitrogen atmosphere.
Thereby, the laminated body 60 (refer FIG. 8) which laminated | stacked the gate electrode 14 and the gate insulating layer 16 on the base material 12 which consists of a polyimide film was produced.

<Formation of Organic Semiconductor Layer 18>
A toluene solution containing 0.3% by mass of C ₈ -BTBT was prepared as the coating liquid A to be the organic semiconductor layer 18.
The laminate 60 was placed on a 90 ° C. hot plate. Next, as conceptually shown in FIG. 8, a support body 62 is placed on the gate insulating layer 16 of the stacked body 60, and a 0.7 mm-thickness is placed on the support body 62 and the gate insulating layer 16. A glass solution adsorbent 64 was placed.
The coating liquid A heated to 90 ° C. was injected between the gate insulating layer 16 and the solution adsorbent 64 and immediately covered with an inverted Petri dish covering the solution adsorber 64.
After toluene was completely evaporated, the Petri dish and the solution adsorber were removed. In this way, the organic semiconductor layer 18 made of a plate crystal film of C ₈ -BTBT was formed on the gate insulating layer 16.
Thereby, the laminated body which laminated | stacked the gate electrode 14, the gate insulating layer 16, and the organic-semiconductor layer 18 on the base material 12 which consists of a polyimide film was produced.

[Example 1]
On the organic semiconductor layer 18 of the stacked body, gold is vacuum-deposited through a nickel shadow mask to form a 1 × 1 mm metal layer 50 having a thickness of 50 nm and serving as the source electrode 24 and the drain electrode 26. did. More than 20 metal layers 50 were formed at intervals of 0.1 mm. When the metal layer 50 was formed, the second opening 32 was formed in the metal layer 50 using a nickel shadow mask as shown in FIG.
The second opening 32 has a rectangular shape with the edge direction of 10 μm and the longitudinal direction of 60 μm, and the longitudinal direction coincides with the channel length direction (distance L2 = 60 μm, size w = 10 μm). The pitch of the second openings 32 in the channel width direction was 56 μm.

  By scanning the metal layer 50 in which the second opening 32 is formed with the laser beam B as shown in FIG. 4, a part of the metal layer 50 is removed by laser ablation to form the first opening 30, and the source The electrode 24 and the drain electrode 26 were formed, and the organic thin film transistor 10 as shown in FIG. 1 was produced.

As the laser, a laser fine processing apparatus manufactured by Hisol Co., Ltd. was used, and an Nd: YAG (yttrium, aluminum, garnet) laser having a wavelength of 532 nm, a pulse width of 6 nsec (nanoseconds), and a repetition frequency of 10 Hz was used. The fluence of the laser was adjusted to 0.21 mJ / cm ² .
The laser beam B was shaped into a 60 × 4 μm rectangle by adjusting the slit (distance L1 = 4 μm). Laser beam scanning was performed such that the longitudinal direction coincided with the scanning direction, and the scanning direction coincided with the channel width direction.
Further, as shown in FIG. 4, the scanning of the laser beam B that forms the first opening 30 is performed in a pulse-like manner on the metal layer 50 with the scanning line coinciding with the center of the second opening 32 in the channel length direction. The scanning beam end of the laser beam B (beam spot) was overlapped by 4 μm, and the end was overlapped with the second opening 32.
Therefore, in this example, the distance L1 of the first opening 30 in the channel length direction is 4 μm, the channel distance L2 of the second opening 32 is 60 μm, and the size w of the second opening 32 in the channel width direction is 10 μm.
The scanning with the laser beam B was performed while the irradiation position (scanning position) of the laser beam B was fixed and the substrate 12 was conveyed at a speed of 0.56 μm / sec in a direction perpendicular to the scanning direction of the laser beam. . In this regard, the other examples are the same.

[Example 2]
Example in which the second opening 32 is not formed on the organic semiconductor layer 18 of the laminate in which the gate electrode 14, the gate insulating layer 16, and the organic semiconductor layer 18 are laminated on the base material 12 made of polyimide film. In the same manner as in Example 1, a metal layer was formed.
By scanning this metal layer with a laser beam, a second opening 32 similar to that in Example 1 was formed in the metal layer by laser ablation.
As the laser for forming the second opening 32, the same laser as that used for forming the first opening 30 in Example 1 was used. The laser beam forming the second opening 32 was shaped into a 10 × 60 μm rectangle (distance L2 = 60 μm, size w = 10 μm) by adjusting the slit. Laser beam scanning was performed so that the short direction coincided with the scanning direction, and the scanning direction coincided with the channel width direction. The pitch of the laser beams was 56 μm.

After the second opening 32 is formed by laser ablation in this way, the first opening 30 is formed by scanning with the same laser beam B as in Example 1, and the source electrode 24 and the drain electrode 26 are formed. An organic thin film transistor 10 as shown was produced.
Therefore, also in this example, the distance L1 of the first opening 30 in the channel length direction is 4 μm, the channel distance L2 of the second opening 32 is 60 μm, and the size w of the second opening 32 in the channel width direction is 10 μm.

[Example 3]
Example in which the second opening 32 is not formed on the organic semiconductor layer 18 of the laminate in which the gate electrode 14, the gate insulating layer 16, and the organic semiconductor layer 18 are laminated on the base material 12 made of polyimide film. 1, a metal layer 54 was formed as shown in FIG.
By scanning the metal layer 54 with a laser beam Ba having a cross-sectional shape as shown by a broken line in FIG. 7, the first opening 30 and the second opening 32 are formed in the metal layer 54 by laser ablation. The source electrode 24 and the drain electrode 26 were formed, and the organic thin film transistor 10 as shown in FIG. 1 was produced.

The laser that forms the first opening 30 and the second opening 32 was the same as the laser that formed the first opening 30 in Example 1.
By adjusting the slit, the laser beam Ba has a cross-sectional shape coupled to a 46 × 4 μm rectangular region corresponding to the first opening 30 and both ends in the longitudinal direction of the region corresponding to the first opening 30. 7 having a 7 × 60 μm region corresponding to the two openings 32. That is, the cross-sectional shape of the laser beam Ba coincides with the short direction of the first opening 30 and the long direction of the second opening 32, and in the channel length direction, the first opening 30 and the second opening 32 are Match the center.
The scanning of the laser beam was performed by matching the longitudinal direction of the region corresponding to the first opening 30 with the scanning direction. In the laser beam scanning, as shown in FIG. 7, the region corresponding to the second opening 32 of the pulsed laser beam Ba (beam spot) overlaps the metal layer 54 by 4 μm in the scanning direction. Went to.
Therefore, also in this example, the distance L1 of the first opening 30 in the channel length direction is 4 μm, the distance L2 of the second opening 32 in the channel length direction is 60 μm, and the size w of the second opening 32 in the channel width direction is 10 μm. is there.

[Example 4]
Prior to the formation of the metal layer 54, pentacene was vacuum-deposited on the organic semiconductor layer 18 of the stacked body to form a charge injection layer 42 (hole injection layer) having a thickness of 50 nm.
Except for this, an organic thin film transistor 10 as shown in FIG. However, the fluence of the laser was adjusted to 0.034 mJ / cm ² .
Therefore, also in this example, the distance L1 of the first opening 30 in the channel length direction is 4 μm, the channel distance L2 of the second opening 32 is 60 μm, and the size w of the second opening 32 in the channel width direction is 10 μm.

[Comparative Example 1]
An organic thin film transistor was fabricated in the same manner as in Example 1 except that the second opening 32 was not formed when the metal layer was formed.
Therefore, in this example, the gap between the source electrode and the drain electrode, that is, the channel length is basically 4 μm constant over the entire area.

[Comparative Example 2]
Prior to the formation of the metal layer, pentacene was vacuum-deposited on the organic semiconductor layer 18 of the stacked body to form a charge injection layer 42 (hole injection layer) having a thickness of 50 nm.
Thereafter, an organic thin film transistor was produced in the same manner as in Example 4 except that the second opening 32 was not formed when the metal layer was formed.
Therefore, also in this example, the gap between the source electrode and the drain electrode, that is, the channel length is basically 4 μm constant over the entire area.

[Evaluation]
By using a laser microfabrication device manufactured by Hisol, using a Nd: YAG pulse laser with a wavelength of 355 nm, a pulse width of 5 nsec, and a repetition frequency of 20 Hz, condensing the laser beam and scanning it so as to surround the metal layer, The organic semiconductor layer 18 was removed by patterning with a width of 20 μm.
Next, the polyimide film was peeled from the glass carrier (removable film attached to the glass carrier), and 20 organic thin film transistors having only the polyimide film as the substrate 12 were produced.

Measuring the gate voltage (I _d -V _g) characteristics - for each organic thin film transistor manufactured, and the electrodes of the organic thin film transistor, by connecting the respective terminals of the manual prober connected to B2912A manufactured by Agilent Technologies Inc., the drain current The average field effect mobility [cm ² / (V · sec)] was calculated for each example and comparative example.
The drain voltage (V _d ) was set to −3V, and the gate voltage (V _g ) was swept from −40V to 40V.
Further, from the measurement result of the drain current-gate voltage characteristics, the number of organic thin film transistors in which the source electrode 24 and the drain electrode 26 were short-circuited was counted for each example and comparative example.
The results are shown in the table below.

As shown in the table, the gap between the source electrode 24 and the drain electrode 26 is spaced apart in the channel width direction from the first opening 30 that separates the source electrode 24 and the drain electrode 26 corresponding to the entire region in the channel width direction. According to the present invention, a plurality of channel lengths (distance L2 in the channel length direction) are formed by the second openings that are longer than the distance L1 in the channel length direction of the first opening 30. Even if the distance L1) is reduced to 4 μm, the short-circuit between the source electrode 24 and the drain electrode 26 hardly occurs.
On the other hand, in the comparative example in which the gap between the source electrode 24 and the drain electrode 26 is formed by only the first opening of 4 μm, a short circuit occurs in nearly half of the organic thin film transistors.
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 10,40 Organic thin-film transistor 12 Base material 14 Gate electrode 16 Gate insulating layer 18 Organic-semiconductor layer 24,102 Source electrode 26,104 Drain electrode 30 1st opening 32 2nd opening 42 Charge injection layer 50,54 Metal layer 60 Laminate 62 Support 64 Solution adsorbent A Coating liquid B, Ba, Bz Laser beam L1, L2 Distance

Claims (12)

A substrate, a gate electrode, a gate insulating layer, an organic semiconductor layer, and a method for producing an organic thin film transistor having a source electrode and a drain electrode,
A step of forming a metal layer to be the source electrode and the drain electrode, and an electrode formation step of forming the source electrode and the drain electrode by removing a part of the metal layer, and
The electrode forming step removing a part of the metal layer by scanning a laser beam to form a first opening separating the source electrode and the drain electrode; and
A plurality of distances in the direction of separation between the first electrode and the drain electrode provided in a direction perpendicular to the direction of separation of the source electrode and the drain electrode by the first opening and communicating with the first opening. A method of manufacturing an organic thin film transistor, comprising: forming a second opening, wherein L2 is longer than a distance L1 in the separation direction between the source electrode and the drain electrode of the first opening.   2. The organic thin film transistor according to claim 1, wherein in the step of forming the metal layer, the step of forming the second opening by patterning the metal layer is performed in the step of forming the metal layer. Production method.   The method for producing an organic thin film transistor according to claim 1, wherein the second opening is formed by removing a part of the metal layer by scanning with a laser beam.   2. The method of manufacturing an organic thin film transistor according to claim 1, wherein in the electrode formation step, the step of forming the first opening and the step of forming the second opening are performed in the same step.   The method for producing an organic thin film transistor according to claim 1, wherein a charge injection layer is formed between the organic semiconductor layer and the source electrode and the drain electrode. Forming the first opening by a pulse laser;
The method for manufacturing an organic thin film transistor according to any one of claims 1 to 5, wherein the second opening overlaps an end portion in the scanning direction of a laser beam by a pulse laser that forms the first opening.   The method for manufacturing an organic thin film transistor according to any one of claims 1 to 6, wherein a distance L1 in a separation direction between the source electrode and the drain electrode of the first opening is 5 µm or less.   The manufacturing method of the organic thin-film transistor of any one of Claims 1-7 which perform the process of forming the said metal layer, after forming the said organic-semiconductor layer. An organic thin film transistor having a base material, a gate electrode, a gate insulating layer, an organic semiconductor layer, and a source electrode and a drain electrode,
A gap between the source electrode and the drain electrode, a first opening separating the source electrode and the drain electrode, and
A plurality of distances in the direction of separation between the first electrode and the drain electrode provided in a direction perpendicular to the direction of separation of the source electrode and the drain electrode by the first opening and communicating with the first opening. An organic thin film transistor, wherein L2 is constituted by a second opening that is longer than a distance L1 in the separation direction between the source electrode and the drain electrode of the first opening.   The organic thin-film transistor of Claim 9 which has a charge injection layer between the said organic-semiconductor layer, and a source electrode and a drain electrode.   11. The organic thin film transistor according to claim 9, wherein a distance L <b> 1 in the separation direction between the source electrode and the drain electrode of the first opening is 5 μm or less.   The organic thin-film transistor according to claim 9, wherein the organic semiconductor layer is located between the support and the source electrode and the drain electrode.