JP2010021402A - Organic tft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic TFT (Thin Film Transistor) which has superior characteristics and high reliability without making the manufacturing process thereof complicated and expensive. <P>SOLUTION: The organic TFT has a source electrode/drain electrode and a source bus which are formed separately and discontinuously on a first base layer, an organic semiconductor film formed by dripping an organic semiconductor solution onto the source electrode/drain electrode, and a conductive pattern formed on a second base layer, the source electrode and source bus being electrically connected to each other through the conductive pattern. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an organic TFT.

  In recent years, a technique for forming a thin film transistor (hereinafter also referred to as TFT) on a substrate has greatly advanced, and in particular, application development to a drive element of an active matrix type large screen display device has been advanced. TFTs that are currently in practical use are manufactured with Si-based inorganic materials such as a-Si and poly-Si, but the manufacture of TFTs using such inorganic materials requires a vacuum process or a high-temperature process. And greatly affects the manufacturing cost.

  Therefore, in order to deal with such problems, various TFTs using organic materials (hereinafter also referred to as organic TFTs) have been studied in recent years. Organic materials have a wider choice of materials than inorganic materials, and the manufacturing process of organic TFTs uses processes with excellent productivity such as printing and coating instead of the vacuum process and high temperature process described above. Cost can be reduced. Furthermore, it may be formed on, for example, a plastic film substrate having poor heat resistance, and is expected to be applied to various fields.

  As a method for applying the organic semiconductor material, there are known droplet application techniques such as an inkjet method and a dispenser method in which a solution in which the organic semiconductor material is dissolved is directly applied. Since the organic semiconductor solution can be prepared so as to be suitable for such a printing method, the organic semiconductor film can be patterned. These techniques are: 1. No vacuum process is required. 2. There is no waste of materials. Since direct patterning is possible, there is an advantage that an etching process is not required as compared with the photolithography method. As a result, manufacturing costs can be reduced, and extensive research has been conducted.

  By the way, in such an organic TFT, in order to obtain excellent electrical characteristics and high reliability, it is necessary to accurately form an organic semiconductor film at a predetermined position with an appropriate film thickness. However, when the organic semiconductor film of the organic TFT is formed by using a printing method such as an inkjet method or a dispenser method, the stability of the organic semiconductor solution, nozzle clogging due to drying of the nozzle surface, There are various unstable factors related to dropping, such as variations in the dropping speed of the dropped organic semiconductor solution due to the increase in concentration, bending until the dropped liquid drops landing, and the like. Further, depending on the surface state of the landing position of the dropped liquid droplet and the contact angle of the liquid droplet, the liquid droplet may move from the landing position. For this reason, the accuracy of 50 μm is the limit, and it is difficult to achieve high definition over the photolithography method. Furthermore, when the dropped droplets spread out before reaching dryness and reach adjacent pixels, patterning defects that lead to increased crosstalk and leakage current, and sufficient film thickness cannot be obtained. There is a problem that good characteristics of the transistor cannot be obtained.

  As one of the methods for achieving high definition, the droplet diameter has been proposed to be small. However, since the nozzle clogging and the bending until the droplets are landed are more disadvantageous, the smaller the diameter, the better. I can't say that.

  Therefore, various techniques have been studied to deal with such problems. For example, plasma is applied to a predetermined position where a droplet is desired to be dropped on a thin film having liquid repellency to make it lyophilic, and a region having lyophilicity surrounded by a peripheral part having liquid repellency is provided. As a result, a technique is known in which the dropped droplets are prevented from flowing out of the application region and the printing accuracy is improved (see Patent Document 1).

In addition, an organic film pattern made of an acrylic synthetic resin having hydrophobicity (liquid repellency) containing a photosensitive material is formed on the source electrode / drain electrode formed on the base layer, and the source electrode / drain electrode Openings are provided in predetermined areas facing each other. Then, the underlying layer exposed through the opening is irradiated with oxygen plasma to make it hydrophilic (lyophilic). That is, the surface of the organic film pattern is hydrophobic and the underlying layer of the opening is hydrophilic, so that the organic thin film pattern becomes a bank (barrier). As a result, a technique is known in which the dropped liquid droplets are prevented from flowing out of the application region and the printing accuracy is improved (see Patent Document 2).
WO2004 / 096551 JP 2007-288130 A

  However, the methods disclosed in Patent Document 1 and Patent Document 2 require a step of plasma irradiation in order to make the underlayer lyophilic. Further, in Patent Document 2, an opening is formed in the organic film pattern. In order to form the provided bank, a process such as a photolithography method is required. For this reason, there is a problem that the manufacturing process becomes complicated and the manufacturing cost increases.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an organic TFT capable of obtaining excellent characteristics and high reliability without incurring complicated manufacturing process and high price. .

  The above object is achieved by the invention described in any one of 1 to 9 below.

1. A source electrode / drain electrode and a source bus that are discontinuously formed on the first underlayer;
An organic semiconductor film formed by dropping an organic semiconductor solution on the source / drain electrodes;
A conductive pattern formed on the second underlayer,
The organic TFT, wherein the source electrode and the source bus are electrically connected through the conductive pattern.

  2. 2. The organic TFT as described in 1 above, wherein the first underlayer is a gate insulating film, and the second underlayer is a base substrate.

  3. 3. The organic TFT as described in 2 above, wherein the conductive pattern and the gate electrode are simultaneously formed of the same material on the second base layer.

  4). 2. The organic TFT as described in 1 above, wherein the first underlayer is a gate insulating film, and the second underlayer is a semiconductor protective film.

  5. 5. The organic TFT as described in 4 above, wherein the conductive pattern and the pixel electrode are simultaneously formed of the same material on the second base layer.

  6). 2. The organic TFT as described in 1 above, wherein the first base layer is a base substrate, and the second base layer is a gate insulating film.

  7). 7. The organic TFT as described in 6 above, wherein the conductive pattern and the gate electrode are simultaneously formed of the same material on the second base layer.

  8). The first to seventh aspects, wherein the source electrode and the source bus are electrically connected to the conductive pattern through an opening provided in the first base layer or the second base layer. The organic TFT according to any one of the above items.

  9. 9. The organic TFT according to any one of 1 to 8, wherein the organic semiconductor solution is dropped using an ink jet method or a dispenser method.

  According to the present invention, the source electrode and the source bus are separated and formed discontinuously on the first underlayer, and are connected via the conductive pattern formed on the second underlayer. did. Thus, when the organic semiconductor solution is dropped on the source / drain electrodes to form the organic semiconductor film, the dropped organic semiconductor solution droplets do not spread to the source bath. As a result, the organic semiconductor film can be accurately formed at a predetermined position with an appropriate film thickness, and excellent characteristics and high reliability can be obtained without incurring complicated manufacturing processes and high costs. .

  Embodiments of an organic TFT according to the present invention will be described below with reference to the drawings. In addition, although this invention is demonstrated based on embodiment of illustration, this invention is not limited to this embodiment.

[Embodiment 1]
First, the structure of the organic TFT according to the first embodiment will be described with reference to FIG. In FIG. 1, the left drawing is a schematic plan view of the organic TFT 1 according to the first embodiment, and the right drawing is a schematic sectional view.

  As shown in FIG. 1, the organic TFT 1 includes a base substrate P, a gate electrode G, a conductive pattern CP, a gate insulating film IF, a source electrode S / drain electrode D, a source bus SB, an organic semiconductor film SF, and a semiconductor protection not shown. This is a bottom gate bottom contact type organic TFT composed of a film or the like.

  In the organic TFT 1 having such a configuration, the source electrode S / drain electrode D and the source bus SB are discontinuously formed on the gate insulating film IF (first underlayer), and the source electrode S and the source The bus SB is connected via a conductive pattern CP formed on the base substrate P (second base layer).

  Since the source electrode S and the drain electrode D are formed of a metal thin film, the surface energy is higher than the surface of the peripheral gate insulating film IF, and the organic semiconductor solution is likely to spread. Therefore, when the organic semiconductor solution is dropped, if the source electrode S and the source bus SB are continuously formed on the gate insulating film IF, the dropped organic semiconductor solution is moved in the direction of the source bus SB. The amount of solution remaining in the wetting spread channel portion is reduced. As a result, it is difficult to stably form the organic semiconductor film SF with an appropriate film thickness in the channel portion.

  Therefore, the inventors of the present application have made extensive studies in order to deal with these problems. As a result, the source electrode S and the source bus SB are separated and formed discontinuously on the gate insulating film IF. The present inventors have found a configuration in which connection is made through the conductive pattern CP formed on the top. Accordingly, when the organic semiconductor solution is dropped on the source electrode S / drain electrode D to form the organic semiconductor film SF, it is possible to prevent the dropped droplet of the organic semiconductor solution from spreading onto the source bus SB. In addition, the organic semiconductor film SF can be accurately formed at a predetermined position with an appropriate film thickness.

  Next, an example of the manufacturing process of the organic TFT 1 having such a configuration will be described with reference to FIG. FIG. 2A to FIG. 2E are schematic diagrams illustrating an example of the manufacturing process of the organic TFT 1. The left diagram on the paper is a schematic plan view, and the right diagram is a schematic sectional view.

  First, the gate electrode G and the conductive pattern CP are formed on the base substrate P (FIG. 2A). The material of the base substrate P is not particularly limited. For example, glass such as soda glass or non-alkali glass, or a resin sheet such as a flexible plastic film can be used. Specific examples of the plastic film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polycarbonate (PC), cellulose triacetate (TAC), and cellulose acetate propionate. Examples thereof include a film made of (CAP) or the like. By using such a plastic film, the weight can be reduced as compared with the case of using a glass substrate, the portability can be improved, and the resistance to impact can be improved. A metal plate such as stainless steel or brass can also be used.

  As materials for the gate electrode G and the conductive pattern CP, Au, Ag, Pb, Al, Cr, Pt, Cu, Mo, ITO, a material obtained by adding a dopant to these when a thin film is formed by sputtering or vapor deposition, etc. Can be used. In the case of the droplet coating method, metal nanoparticle ink in which metal nanoparticles such as Ag nanoparticles, Au nanoparticles, and AgPb nanoparticles are dispersed in a solvent, and metal oxide in which metal oxides such as ITO nanoparticles are dispersed in a solvent An organic material-dispersed ink in which an organic material such as nanoparticle ink or PEDOT / PSS is dispersed in a solvent can be used. As a forming method, a method of patterning a base substrate P on which a thin film of an electrode material is formed using a sputtering method or a vapor deposition method using a photolithography method, various printing methods, an inkjet method, or the like A thin film can be formed only on a desired portion by using a droplet coating method.

  Next, the gate insulating film IF is formed (FIG. 2B). As a material of the gate insulating film IF, inorganic oxides such as silicon oxide, aluminum oxide, tantalum oxide, and titanium oxide, and inorganic nitrides such as silicon nitride and aluminum nitride can be used. Or, polyimide, polyamide, polyester, polyacrylate, photo-curing polymer of photo radical polymerization, photo cation polymerization, copolymer containing acrylonitrile component, organic compound such as polyvinyl phenol, polyvinyl alcohol, novolac resin, cyanoethyl pullulan Etc. can also be used. As a forming method, for example, a method of patterning an insulating film formed by a coating method such as spin coating in addition to a vacuum evaporation method, a CVD method, a sputtering method, an atmospheric pressure plasma method, or the like using a photolithography method or the like A thin film can be formed only on a desired portion by using various printing methods or droplet coating methods such as inkjet. At this time, openings IFa and IFb are formed in regions located at both ends of the conductive pattern CP of the gate insulating film IF.

  Next, a source electrode S / drain electrode D and a source bus SB are formed (FIG. 2C). As the material of the source electrode S / drain electrode D and the source bus SB, the same material as that of the gate electrode G can be used. After cleaning the base substrate P on which the gate insulating layer IF is formed, it can be formed by using a photolithography method, various printing methods, a droplet coating method, or the like, similarly to the method for forming the gate electrode G described above. . At this time, the source electrode S and the source bus SB are connected to and conductive with the conductive pattern CP formed on the base substrate P through the openings IFa and IFb formed in the gate insulating film IF, respectively.

  Next, after dropping the organic semiconductor solution SL on the channel portion formed by the source electrode S and the drain electrode D (FIG. 2D), it is dried to form the organic semiconductor film SF (FIG. 2E). )).

  As the organic semiconductor material, a polycyclic aromatic compound, a conjugated polymer, or the like can be used, but is not particularly limited. A polymer material, an oligomer, or a low-molecular material may be used, and a material in which molecules are regularly arranged by intermolecular interaction to form a crystal after film formation is particularly preferable. Pentacene, porphyrin, phthalocyanine, oligothiophene, oligophenylene, polythiophene, polyphenylene, and derivatives thereof can be used. Specifically, pentacene, 6,13-bis (triisopropylsilylethynyl) pentacene, tetrabenzoporphyrin, poly (3-hexylthiophene), or the like can be used. Further, these precursors can be converted into an organic semiconductor material or the like by heat treatment after the film formation.

  The application method of the organic semiconductor solution SL can reduce the manufacturing cost because the printing method such as screen printing, ink jet method, micro contact printing, SIJ, dispenser method, letterpress, transfer and the like can be patterned simultaneously with the application. This is preferable. In particular, it is particularly preferable to use a droplet coating method such as an inkjet method, SIJ, or a dispenser method.

  In the case of using a droplet coating method, the organic semiconductor material is preferably dissolved or dispersed in a solvent among the materials described above, and a soluble side chain is added to increase the solubility in an organic low molecular weight material. The present invention can also be applied to a provided solution or a solution of a semiconductor precursor.

  Moreover, the solvent used for the organic semiconductor solution SL is not particularly limited as long as it has the solubility of the organic semiconductor material and the viscoelasticity and boiling point necessary for ejection by the inkjet method. A suitable solvent for the organic semiconductor material can be selected from the group, aliphatic hydrocarbons, alcohols, ketones, ethers, esters, halogenated hydrocarbons, phenols and the like.

  A semiconductor protective film (not shown) is appropriately formed to shield and protect the organic semiconductor film SF from the external atmosphere.

[Embodiment 2]
First, the structure of the organic TFT according to the second embodiment will be described with reference to FIG. In FIG. 3, the left drawing is a schematic plan view of the organic TFT 1 according to the second embodiment, and the right drawing is a schematic sectional view.

  As shown in FIG. 3, the organic TFT 1 includes a base substrate P, a gate electrode G, a gate insulating film IF, a source electrode S / drain electrode D, a source bus SB, an organic semiconductor film SF, a semiconductor protective film PF, and a pixel electrode E. This is a bottom gate bottom contact type organic TFT composed of a conductive pattern CP and the like, as in the first embodiment.

  In the organic TFT 1 having such a configuration, the source electrode S / drain electrode D and the source bus SB are discontinuously formed on the gate insulating film IF (first underlayer), and the source electrode S and the source The bus SB is connected via a conductive pattern CP formed on the semiconductor protective film PF (second base layer).

  Even in such a configuration, the source electrode S and the source bus SB are discontinuously formed on the gate insulating film IF. Thus, as in the case of the first embodiment, when the organic semiconductor solution is dropped on the source electrode S / drain electrode D to form the organic semiconductor film SF, the dropped organic semiconductor solution droplets are transferred to the source bus SB. Therefore, the organic semiconductor film SF can be accurately formed at a predetermined position with an appropriate film thickness.

  Next, an example of a manufacturing process of the organic TFT 1 having such a configuration will be described with reference to FIG. 4A to 4H are schematic views showing an example of the manufacturing process of the organic TFT 1. The left side of the drawing is a schematic plan view, and the right side is a schematic cross-sectional view.

  The steps from the formation of the gate electrode G to the formation of the organic semiconductor protective film SF shown in FIGS. 4A to 4E are the steps of forming the conductive pattern CP in the case of Embodiment 1, and the source electrode S. Is substantially the same except for the step of connecting the conductive pattern CP of the source bus SB and the description thereof is omitted.

In FIG. 4F, a semiconductor protective film PF is formed. As the material of the semiconductor protective film PF, parylene C, SiO ₂ , SiNx, or the like can be used, but is not particularly limited as long as the performance of protecting the organic semiconductor film SF is sufficient. Also, the forming method is not particularly limited as long as it is carried out by a commonly used method.

  Next, openings PFa, PFb, and PFc are formed in regions located at the ends of the source electrode S, source bus SB, and drain electrode D of the semiconductor protective film PF (FIG. 4G). As a forming method, for example, a laser can be used.

  Next, the pixel electrode E and the conductive pattern CP are formed (FIG. 4H). As the material of the pixel electrode E and the conductive pattern CP, the same material as that of the gate electrode G can be used. Further, as in the case of the gate electrode G, the formation method can be formed using a photolithography method, various printing methods, a droplet coating method, or the like. At this time, both ends of the conductive pattern CP are electrically connected to the source electrode S and the source bus SB formed on the gate insulating film IF through the openings PFa and PFb formed in the semiconductor protective film PF, respectively. . Further, the pixel electrode E is connected to the drain electrode D formed on the gate insulating film IF through the opening portion PFc formed in the semiconductor protective film PF and becomes conductive.

[Embodiment 3]
First, the structure of the organic TFT according to the third embodiment will be described with reference to FIG. In FIG. 5, the left drawing is a schematic plan view of the organic TFT 1 according to the third embodiment, and the right drawing is a schematic sectional view.

  As shown in FIG. 5, the organic TFT 1 includes a base substrate P, a source electrode S / drain electrode D, a source bus SB, an organic semiconductor film SF, a gate insulating film IF, a gate electrode G, a conductive pattern CP, and the like. A top gate bottom contact type organic TFT.

  In the organic TFT 1 having such a configuration, the source electrode S, the drain electrode D, and the source bus SB are discontinuously formed on the base substrate P (first base layer), and the source electrode S and the source bus are formed. The SB is connected via a conductive pattern CP formed on the gate insulating film IF (second base layer).

  Even in such a configuration, the source electrode S and the source bus SB are discontinuously formed on the base substrate P. Thus, as in the case of the first embodiment, when the organic semiconductor solution is dropped on the source electrode S / drain electrode D to form the organic semiconductor film SF, the dropped organic semiconductor solution droplets are transferred to the source bus SB. Therefore, the organic semiconductor film SF can be accurately formed at a predetermined position with an appropriate film thickness.

  Next, an example of the manufacturing process of the organic TFT 1 having such a configuration will be described with reference to FIG. 6A to 6E are schematic views showing an example of the manufacturing process of the organic TFT 1. The left side of the drawing is a schematic plan view, and the right side is a schematic cross-sectional view.

  First, the source electrode S / drain electrode D and the source bus SB are formed on the base substrate P (FIG. 6A). The materials of the base substrate P, the source electrode S / drain electrode D, and the source bus SB, and the formation method thereof are substantially the same as those in the first embodiment, and the description thereof is omitted.

  Next, after dropping the organic semiconductor solution SL on the channel portion formed by the source electrode S and the drain electrode D (FIG. 6B), the organic semiconductor film SF is formed by drying (FIG. 6C). )). The organic semiconductor material and the coating method of the organic semiconductor solution SL are generally the same as those in the first embodiment, and the description thereof is omitted.

  Next, the gate insulating film IF is formed (FIG. 6D). The material and formation method of the gate insulating film IF are generally the same as those in the first embodiment, and the description thereof is omitted. At this time, openings IFa and IFb are formed in regions located at the ends of the source electrode S and the source bus SB of the gate insulating film IF.

  Next, the gate electrode G and the conductive pattern CP are formed (FIG. 6E). The material and formation method of the gate electrode G and the conductive pattern CP are substantially the same as those in the first embodiment, and a description thereof will be omitted. At this time, both ends of the conductive pattern CP are electrically connected to the source electrode S and the source bus SB formed on the base substrate P through the openings IFa and IFb formed in the gate insulating film IF, respectively.

  In the first and second embodiments described above, the source electrode S and the drain electrode D are formed in a rectangular shape, but may be formed in a semicircular shape as shown in FIG. The force of the organic semiconductor solution SL dropped on the channel portion of the source electrode S / drain electrode D acts to be rounded by surface tension. For this reason, when the electrode shape is made round according to the shape of the droplet, the landing stability on the source electrode S / drain electrode D is high, and the positional accuracy of the formed organic semiconductor film SF can be improved. .

  Next, examples of the organic TFT 1 according to the embodiment of the present invention will be described.

Example 1
Example 1 is an example of the organic TFT according to the first embodiment.

  First, after applying a photosensitive resist to a glass substrate (FIG. 2A: base substrate P) having a thickness of 125 nm and having a Cr film sputtered on the surface thereof, a gate electrode G, a conductive pattern Exposure and development were performed through a photomask having a CP shape to form a gate electrode G and a resist layer having a conductive pattern CP shape. After the etching of Cr, the resist layer was removed to form a gate electrode G and a conductive pattern CP (FIG. 2A).

  Next, using a spin coating method, a photosensitive material was applied to form a gate insulating film IF having a thickness of 500 nm (FIG. 2B). At this time, openings IFa and IFb were formed in regions located at both ends of the conductive pattern CP of the gate insulating film IF using a photolithography method.

  Next, after applying a lift-off resist on the gate insulating film IF and patterning using a photolithography method, a Cr film was formed in this order with a thickness of 5 nm and Au with a thickness of 50 nm. Thereafter, ultrasonic cleaning was performed with dimethylformamide at room temperature to remove the lift-off resist in unnecessary portions, and the source electrode S / drain electrode D and source bus SB were formed (FIG. 2C). The distance between the source electrode S and the drain electrode D, which is the channel length, was 10 μm, and the channel width was 100 μm. At this time, the source electrode S and the source bus SB are connected to and conductive with the conductive pattern CP formed on the base substrate P through the openings IFa and IFb formed in the gate insulating film IF, respectively.

  Next, a solution in which 5 mass% of 6,13-bistriisopropylsilylethynylpentacene is dissolved in tetralin having a boiling point of 207.4 ° C. as an organic semiconductor solution SL is formed on the channel portion formed by the source electrode S and the drain electrode D. Then, after dropping using an inkjet method (FIG. 2D), the organic semiconductor film SF was formed by drying (FIG. 2E), and a bottom gate bottom contact type organic TFT 1 was completed. As the ink jet method, an ink jet head manufactured by Konica Minolta was used. The dropping pattern was 100 × 80 dots and 352.5 μm in pitch, and the organic semiconductor solution SL was dropped into a predetermined channel region by one scan.

(Example 2)
Example 2 is an example of the organic TFT according to the second embodiment.

  First, a photosensitive resist is applied to a glass substrate (FIG. 4A: base substrate P) having a thickness of 125 nm and having a Cr film sputtered on the surface, and then the shape of the gate electrode G is changed. The resist layer having the shape of the gate electrode G was formed by exposure and development through a photomask. After the etching of Cr, the resist layer was removed to form the gate electrode G (FIG. 4A).

  Next, using a spin coating method, a photosensitive material was applied to form a gate insulating film IF having a thickness of 500 nm (FIG. 4B). In order to protect the terminal portion of the gate electrode G, a lift-off resist (manufactured by ZEON Co., Ltd.) was applied in advance by a spin coating method, and then patterned using a photolithography method to form a protective film. After forming the gate insulating film IF, ultrasonic cleaning was performed with dimethylformamide at room temperature to remove the unnecessary portion of the lift-off resist and lead out the terminals.

  Next, after applying a lift-off resist on the gate insulating film IF and patterning using a photolithography method, a Cr film was formed in this order with a thickness of 5 nm and Au with a thickness of 50 nm. Thereafter, ultrasonic cleaning was performed with dimethylformamide at room temperature to remove the lift-off resist in unnecessary portions, and the source electrode S / drain electrode D and source bus SB were formed (FIG. 4C). The distance between the source electrode S and the drain electrode D, which is the channel length, was 10 μm, and the channel width was 100 μm.

  Next, a solution in which 5 mass% of 6,13-bistriisopropylsilylethynylpentacene is dissolved in tetralin having a boiling point of 207.4 ° C. as an organic semiconductor solution SL is formed on the channel portion formed by the source electrode S and the drain electrode D. Then, after dropping using an ink jet method (FIG. 4D), it was dried to form an organic semiconductor film SF (FIG. 4E). As the ink jet method, an ink jet head manufactured by Konica Minolta was used. The dropping pattern was 100 × 80 dots and 352.5 μm in pitch, and the organic semiconductor solution SL was dropped into a predetermined channel region by one scan.

  Next, the parylene C was formed on the entire surface of the base substrate P on which the organic semiconductor film SF was formed, thereby forming the semiconductor protective film PF (FIG. 4F).

  Next, openings PFa, PFb, and PFc were formed using a laser in regions located at the ends of the source electrode S, source bus SB, and drain electrode D of the semiconductor protective film PF (FIG. 4G). ).

  Next, after applying a lift-off resist on the semiconductor protective film PF and patterning using a photolithography method, an ITO thin film was formed using a sputtering method. Thereafter, the lift-off resist in unnecessary portions was removed, and pixel electrodes E and conductive patterns CP were formed (FIG. 4H). At this time, both ends of the conductive pattern CP are electrically connected to the source electrode S and the source bus SB formed on the gate insulating film IF through the openings PFa and PFb formed in the semiconductor protective film PF, respectively. In addition, the pixel electrode E is connected and connected to the drain electrode D formed on the gate insulating film IF through the opening PFc formed in the semiconductor protective film PF. In this way, a bottom gate bottom contact type organic TFT 1 was completed.

(Example 3)
Example 3 is an example of the organic TFT according to the third embodiment.

  First, a lift-off resist is applied to a glass substrate having a thickness of 0.7 mm (FIG. 6A: base substrate P), patterned using a photolithography method, and then Au is deposited to a thickness of 50 nm using a sputtering method. The film was formed. Thereafter, unnecessary portions of the lift-off resist were removed, and the source electrode S / drain electrode D and the source bus SB were formed (FIG. 6A).

  Next, a solution in which 5 mass% of 6,13-bistriisopropylsilylethynylpentacene is dissolved in tetralin having a boiling point of 207.4 ° C. as an organic semiconductor solution SL is formed on the channel portion formed by the source electrode S and the drain electrode D. Then, after dropping using an ink jet method (FIG. 6B), the organic semiconductor film SF was formed by drying (FIG. 6C). As the ink jet method, an ink jet head manufactured by Konica Minolta was used. The dropping pattern was 100 × 80 dots and 352.5 μm in pitch, and the organic semiconductor solution SL was dropped into a predetermined channel region by one scan.

  Next, using a spin coating method, a photosensitive material was formed to form a gate insulating film IF having a thickness of 500 nm (FIG. 6D). At this time, openings IFa and IFb were formed in regions located at both ends of the conductive pattern CP of the gate insulating film IF using a photolithography method.

  Next, a lift-off resist was applied on the gate insulating film IF, patterned using a photolithography method, and then a Cr thin film was formed using a sputtering method. Thereafter, the lift-off resist in unnecessary portions was removed, and a gate electrode G and a conductive pattern CP were formed (FIG. 6E). At this time, both ends of the conductive pattern CP are electrically connected to the source electrode S and the source bus SB formed on the base substrate P through the openings IFa and IFb formed in the gate insulating film IF, respectively. Thus, the top gate bottom contact type organic TFT 1 was completed.

  Thus, for each example, 20 elements of the organic TFT 1 were manufactured, and the shape of the organic semiconductor film SF was observed with an optical microscope and AFM (manufactured by Keyence Corporation). It was confirmed that it was well formed in the channel part.

  As described above, the organic TFT 1 according to the embodiment of the present invention is formed on the second base layer by discontinuously forming the source electrode S and the source bus SB on the first base layer. The connection is made through a conductive pattern. As a result, when the organic semiconductor solution is dropped on the source electrode S / drain electrode D to form the organic semiconductor film SF, the dropped droplet of the organic semiconductor solution does not spread onto the source bus SB. As a result, the organic semiconductor film SF can be accurately formed at a predetermined position with an appropriate film thickness, and excellent characteristics and high reliability can be obtained without causing a complicated manufacturing process and high price. it can.

It is a figure which shows the structure of the organic TFT by Embodiment 1 of this invention. It is a schematic diagram which shows the manufacturing process of the organic TFT by Embodiment 1 of this invention. It is a figure which shows the structure of the organic TFT by Embodiment 2 of this invention. It is a schematic diagram which shows the manufacturing process of organic TFT by Embodiment 2 of this invention. It is a figure which shows the structure of the organic TFT by Embodiment 3 of this invention. It is a schematic diagram which shows the manufacturing process of organic TFT by Embodiment 3 of this invention. It is a figure which shows the shape by another example of a source electrode / drain electrode.

Explanation of symbols

1 Organic TFT (Organic Thin Film Transistor)
CP conductive pattern D drain electrode E pixel electrode G gate electrode IF gate insulating film P base substrate PF semiconductor protective film S source electrode SB source bus SF organic semiconductor film SL organic semiconductor solution

Claims (9)

A source electrode / drain electrode and a source bus that are discontinuously formed on the first underlayer;
An organic semiconductor film formed by dropping an organic semiconductor solution on the source / drain electrodes;
A conductive pattern formed on the second underlayer,
The organic TFT, wherein the source electrode and the source bus are electrically connected through the conductive pattern. The organic TFT according to claim 1, wherein the first underlayer is a gate insulating film, and the second underlayer is a base substrate. The organic TFT according to claim 2, wherein the conductive pattern and the gate electrode are simultaneously formed of the same material on the second base layer. 2. The organic TFT according to claim 1, wherein the first base layer is a gate insulating film, and the second base layer is a semiconductor protective film. The organic TFT according to claim 4, wherein the conductive pattern and the pixel electrode are simultaneously formed of the same material on the second base layer. 2. The organic TFT according to claim 1, wherein the first underlayer is a base substrate, and the second underlayer is a gate insulating film. The organic TFT according to claim 6, wherein the conductive pattern and the gate electrode are simultaneously formed of the same material on the second base layer. 8. The source electrode and the source bus are electrically connected to the conductive pattern through an opening provided in the first base layer or the second base layer. Organic TFT of any one of these. The organic TFT according to claim 1, wherein the organic semiconductor solution is dropped using an inkjet method or a dispenser method.

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