JP2015201520A - Semiconductor film formation method and transistor manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor film formation method and a transistor manufacturing method, which can be easily performed and improve homogeneity on a channel of an obtained semiconductor film.SOLUTION: In a semiconductor film formation method and a transistor manufacturing method of forming a semiconductor film of the transistor by the film formation method, when forming the semiconductor film by dehydrating an ink 2 containing a semiconductor material, which is provided on a channel 13, the ink 2 on the channel 13 is dehydrated by light irradiation in a manner such that a temperature distribution of the ink 2 on the channel 13 becomes asymmetry in a source electrode 11-drain electrode 12 direction.

Description

  The present invention relates to a method for forming a semiconductor film and a method for manufacturing a transistor, and more specifically, a method for forming a semiconductor film and a method for manufacturing a transistor in which light irradiation is performed when a semiconductor film is formed by drying ink containing a semiconductor material. About.

  In recent years, as a method for manufacturing an electronic device, research and development of a so-called printed electronics that is manufactured by a printing method without using a conventional photolithography process or a vacuum process has been actively performed.

  Specific examples include LCD color filters and liquid crystal material printing, OLED light emitting and injection layers, electronic paper TFT backplanes, PCB and FPC electrode formation, solar cell wiring, transparent conductive films and touch panels. Many attempts have been made to print devices.

  The formation of the organic semiconductor layer of the organic transistor has been studied from the production by the conventional vacuum method to the printing under the atmospheric pressure, particularly the lamination by the ink jet method. By forming a coating film by coating and printing, equipment necessary for the vacuum process is unnecessary, and expensive materials can be saved, so that a significant cost reduction is possible.

  In the case of using a coating solution containing an organic semiconductor material, there is a problem that it is difficult to obtain homogeneity of the organic semiconductor material in the organic semiconductor film obtained by drying the coating liquid.

  The applicant of the present application has so far disclosed that, in Patent Document 1, when forming an organic semiconductor film by a coating method, the channel region does not include the center of gravity (center) of the organic semiconductor film in which the crystal orientation is likely to be disturbed. Thus, a technique for improving the carrier mobility is disclosed. Patent Document 2 also describes a similar technique.

  Patent Document 3 states that an organic semiconductor layer with high orientation can be realized by providing a high surface energy part having high affinity with ink on a part of the electrode surface.

  In Patent Document 4 and Non-Patent Document 1, a solution carrying member is provided on the surface of a base material, a solution fillet is formed so as to rise on the side surface of the solution carrying member, and the fillet is attached to the solution carrying member during drying. It is shown that a thin film is formed while retracting to the side.

WO2007 / 135911 JP 2011-233724 A JP 2011-222801 A WO2013 / 024678 Takeya Laboratory, the University of Tokyo, “Creation of high performance organic semiconductor materials based on organic synthetic chemistry”, [online], [March 25, 2013 search], Internet <URL: http: //www.organicel. ku-tokyo.ac.jp/wordpress/wp-content/uploads/2013/12/takeyalab_chem.pdf#search = '% E7% AB% B9% E8% B0% B7 + edge + casting'〉

  In the techniques described in Patent Documents 1 and 2, there are cases where the formation region of the semiconductor film has to be widely extended to an unnecessary region. In some cases, it is difficult to form a semiconductor film, and a technique that can be more easily implemented is required.

  The technique described in Patent Document 3 is difficult to implement easily because the applicable base is limited or a base processing step is required.

  The techniques described in Patent Literature 4 and Non-Patent Literature 1 require a process for removing the solution-carrying member, making the process complicated and difficult to implement easily.

  The present inventors have found that, when drying ink containing a semiconductor material, unlike the conventional approach, the homogeneity of the semiconductor film on the channel can be easily improved by using the energy supplied by light irradiation. To the present invention.

  Therefore, an object of the present invention is to provide a method for forming a semiconductor film and a method for manufacturing a transistor that can be easily implemented and can improve the homogeneity of the obtained semiconductor film on the channel.

  Other problems of the present invention will become apparent from the following description.

  The above problems are solved by the following inventions.

1.
When forming the semiconductor film by drying the ink containing the semiconductor material applied to the channel, the ink is dried so that the temperature distribution of the ink on the channel is asymmetric in the source electrode-drain electrode direction by light irradiation. A method for forming a semiconductor film, comprising:

2.
2. The method of forming a semiconductor film according to claim 1, wherein the light absorption heating element is arranged so that the temperature distribution of the ink on the channel is asymmetric in the source electrode-drain electrode direction.

3.
3. The method for forming a semiconductor film according to claim 2, wherein the light-absorbing heating element includes the source electrode and the drain electrode having different absorbances.

4).
4. The method of forming a semiconductor film as described in 2 or 3, wherein the light absorption heating element is constituted by the source electrode and the drain electrode having different shapes and / or areas.

5.
5. The method of forming a semiconductor film as described in any one of 2 to 4, wherein the light absorption heating element is configured by a dummy heating pattern.

6).
6. The method of forming a semiconductor film according to any one of 1 to 5, wherein light irradiation is performed by pattern exposure so that the temperature distribution of the ink in the channel region is asymmetric in the source electrode-drain electrode direction.

7).
A method for forming a semiconductor film, characterized in that, when an ink containing a semiconductor material is dried to form a semiconductor film, the final drying region of the ink is shifted by light irradiation.

8).
8. The method of forming a semiconductor film according to claim 7, wherein the ink is applied across the inside and outside of the channel region, and the final dry region of the ink is shifted from the inside of the channel region to the outside of the channel region by the light irradiation. .

9.
When a semiconductor film is formed by drying ink containing a semiconductor material, a temperature gradient is formed in the ink by light irradiation, and the drying direction of the ink is directed from the high temperature side to the low temperature side in the temperature gradient. A method for forming a semiconductor film.

10.
10. The method of forming a semiconductor film according to claim 9, wherein the temperature gradient is formed in the ink in the channel region.

11.
A method for manufacturing a transistor including a semiconductor film, wherein the semiconductor film is formed by the method for forming a semiconductor film according to any one of 1 to 10 above.

  According to the present invention, it is possible to provide a method for forming a semiconductor film and a method for manufacturing a transistor that can be easily implemented and can improve the homogeneity of the obtained semiconductor film on a channel.

Diagram conceptually explaining asymmetry of temperature distribution of ink on channel The top view explaining an example of the 1st aspect of the formation method of the semiconductor film of this invention The top view explaining an example of the 2nd aspect of the formation method of the semiconductor film of this invention The top view explaining the other example of the 2nd aspect of the formation method of the semiconductor film of this invention The top view explaining the other example of the 2nd aspect of the formation method of the semiconductor film of this invention The top view explaining the other example of the 2nd aspect of the formation method of the semiconductor film of this invention The top view explaining an example of the 3rd aspect of the formation method of the semiconductor film of this invention The top view explaining an example of the 4th aspect of the formation method of the semiconductor film of this invention The figure explaining the final drying area of ink Explanatory drawing showing an example of forming a bottom gate / bottom contact type thin film transistor Explanatory drawing showing an example of forming a bottom gate / top contact type thin film transistor Explanatory drawing showing an example of forming a top gate / bottom contact type thin film transistor Explanatory drawing showing an example of forming a top gate / top contact type thin film transistor Schematic side view of an essential part showing an example of a forming apparatus for forming a semiconductor film Plan view of the forming apparatus shown in FIG. The figure explaining an Example The figure explaining an Example The figure explaining an Example A diagram explaining a comparative example A diagram explaining a comparative example The figure explaining an Example

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  In the present invention, when an ink containing a semiconductor material applied on a substrate (hereinafter sometimes simply referred to as ink) is dried to form a semiconductor film, light irradiation is performed to dry the ink. As the energy, thermal energy converted from light energy on the substrate is used.

  By using thermal energy converted from light energy, the ink can be dried such that the temperature distribution of the ink on the channel is asymmetric in the source electrode-drain electrode direction.

  “The temperature distribution of the ink on the channel is asymmetrical in the source electrode-drain electrode direction” means that energy conversion that converts the light energy of the irradiated light into thermal energy is either on the source electrode side or the drain electrode side on the substrate. In this state, the heat generated due to light irradiation is biased to either the source electrode side or the drain electrode side.

  FIG. 1 is a diagram conceptually illustrating the asymmetry of the temperature distribution of ink on a channel.

  FIG. 1A is a plan view of a base material on which a semiconductor layer is formed.

  1 is a base material, 11 is a source electrode, 12 is a drain electrode, and 13 is a channel between the source electrode 11 and the drain electrode 12.

  In the present invention, “source electrode-drain electrode direction (hereinafter also referred to as SD direction)” refers to a direction connecting the source electrode 11 and the drain electrode 12 in the shortest distance. In the figure, the SD direction is indicated by the left and right arrows. This SD direction basically coincides with the direction along the carrier movement direction when the substrate 1 is viewed in plan.

  In the SD direction, A is the boundary between the source electrode 11 and the channel 13, B is the boundary between the drain electrode 12 and the channel 13, and C is the midpoint of the line connecting the source electrode 11 and the drain electrode 12 in the SD direction. It is.

  Ink 2 containing a semiconductor material is applied on the channel 13 (also referred to as a channel region) so as to be in contact with the source electrode 11 and the drain electrode 12. Here, the ink 2 is applied across the inside and outside of the channel 13.

  FIG. 1B is a graph conceptually showing the temperature distribution of the ink 2 on the channel 13 in the SD direction in FIG. 1A. The horizontal axis represents the position in the SD direction, and the vertical axis represents the temperature of the ink 2. Show.

  In FIG. 1B, an example in which the temperature distribution of the ink 2 on the channel 13 is symmetric in the SD direction is indicated by a broken line, and an asymmetric example is conceptually indicated by a solid line.

  The symmetrical temperature distribution (broken line) can be made to coincide with the temperature distribution of C → B when the temperature distribution of C → A is inverted about the vertical line passing through C as an axis.

  On the other hand, the asymmetric temperature distribution (solid line) does not coincide with the temperature distribution of C → B even if the temperature distribution of C → A is reversed with the vertical axis passing through C as the axis. In the illustrated example, the temperature of the ink 2 on the channel 13 gradually increases from the source electrode 11 side toward the drain electrode 12 side. Thus, it is also preferable that the temperature of the ink 2 on the channel 13 gradually increases from A to B, preferably exponentially (exponentially). The example of the asymmetric temperature distribution shown here is conceptual only, and is not limited to such an example. As described above, energy conversion that changes the light energy of irradiation light into thermal energy is ubiquitously generated on the substrate so as to be biased to either the source electrode side or the drain electrode side, thereby causing light irradiation. It suffices that the amount of heat generated is biased to either the source electrode side or the drain electrode side.

  By drying the ink 2 so that the temperature distribution of the ink 2 on the channel 13 is asymmetric in the SD direction, the drying of the ink 2 proceeds anisotropically in the SD direction on the channel 13. Specifically, the presence of the temperature distribution makes it easier to proceed from the high temperature side to the low temperature side. In the example shown in the figure, it is easy to proceed from the drain electrode 12 side to the source electrode 11 side.

  By drying the ink 2 anisotropically as described above, the crystal growth direction of the semiconductor material in the semiconductor film formed on the channel 13 can be adjusted. That is, in the semiconductor film, the ratio of the region in which the crystal growth direction is disturbed can be reduced, and the ratio of the region in which the crystal growth direction is arranged can be increased.

  In addition, the drying direction of the ink 2 can be directed from the high temperature side to the low temperature side in the temperature gradient formed in the ink by light irradiation. Thereby, it is possible to prevent the traveling direction of drying from locally changing due to the influence of slight impurities existing on the base material 1 or the interface between different materials on the base material 1 such as between the electrode and the insulating film. You can also. This can also contribute to adjusting the crystal growth direction.

  Therefore, the obtained semiconductor film has an effect of improving the homogeneity on the channel 13 and can contribute to realization of high mobility in the transistor.

  Since energy conversion for converting light energy into heat energy on the substrate 1 is likely to occur locally, an asymmetric temperature distribution can be suitably imparted to the ink even in a minute region such as the channel 13.

  Compared with the conventional techniques described in Patent Documents 1 to 3 and Non-Patent Document 1, the versatility is high and an effect that can be easily implemented can be obtained.

  In the first to third aspects described below, an asymmetric temperature distribution is formed mainly by the configuration of the light absorption heating element provided on the substrate 1. In the fourth aspect, an asymmetric temperature distribution is formed mainly by the irradiation mode of light irradiation.

  FIG. 2 is a plan view for explaining an example of the first aspect of the method for forming a semiconductor film of the present invention.

  In the first aspect, an asymmetric temperature distribution is formed by the configuration (particularly the material) of the light absorption heating element in the base material 1. Here, the source electrode 11 and the drain electrode 12 are used as the light absorption heating element.

  In the first embodiment, the source electrode 11 and the drain electrode 12 have a difference in absorbance with respect to irradiation light. Here, the absorbance is the absorbance with respect to the entire emission wavelength of the irradiation light irradiated when the ink 2 is dried.

  When the source electrode 11 and the drain electrode 12 are irradiated with light, there is a difference in efficiency in converting the light energy of the irradiated light into heat energy.

  Thereby, when the ink 2 is dried by light irradiation, the temperature distribution of the semiconductor ink 2 in the channel region 13 can be asymmetric in the SD direction.

  A method for giving a difference in absorbance between the source electrode 11 and the drain electrode 12 is not particularly limited. For example, a method of forming the source electrode 11 and the drain electrode 12 with materials having different absorbances can be preferably exemplified.

  More specifically, for example, the source electrode 11 is formed of a conductive polymer and the drain electrode 12 is formed of metal, or conversely, the source electrode 11 is formed of metal and the drain electrode 12 is formed. A method such as formation with a conductive polymer can be used.

  In addition, a method of forming the source electrode 11 and the drain electrode 12 with conductive polymers having different absorbances, a method of forming the source electrode 11 and the drain electrode 12 with metals having different absorbances, and the like can be preferably used.

  Although the material which forms the source electrode 11 and the drain electrode 12 will not be specifically limited if it has electroconductivity, For example, a conductive polymer and a metal can be illustrated.

  The conductive polymer is not particularly limited, but a conductive polymer containing a π-conjugated conductive polymer and a polyanion can be preferably used.

  Examples of π-conjugated conductive polymers include polythiophenes (including basic polythiophenes, the same applies hereinafter), polypyrroles, polyindoles, polycarbazoles, polyanilines, polyacetylenes, polyfurans, polyparaphenylene vinylenes, Chain conductive polymers such as polyazulenes, polyparaphenylenes, polyparaphenylene sulfides, polyisothianaphthenes, and polythiazyl can be used.

  Specific examples of polyanions include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacrylic acid ethyl sulfonic acid, polyacrylic acid butyl sulfonic acid, poly-2-acrylamido-2-methylpropane sulfonic acid, polyisoprene sulfone. Examples include acid, polyvinyl carboxylic acid, polystyrene carboxylic acid, polyallyl carboxylic acid, polyacryl carboxylic acid, polymethacryl carboxylic acid, poly-2-acrylamido-2-methylpropane carboxylic acid, polyisoprene carboxylic acid, polyacrylic acid and the like. . These homopolymers may be sufficient and 2 or more types of copolymers may be sufficient.

  A commercially available material can also be preferably used for the conductive polymer used in the present invention. For example, a conductive polymer (abbreviated as PEDOT-PSS) made of poly (3,4-ethylenedioxythiophene) and polystyrenesulfonic acid is commercially available.

  The metal is not particularly limited as long as it has excellent conductivity, and examples thereof include metals such as gold, silver, copper, iron, nickel, and chromium, and alloys containing one or more of these. A metal may be used individually by 1 type and may be used in mixture of multiple types. It is also preferable to sinter metal nanoparticles made of these metals to form an electrode. As the average particle diameter of the metal nanoparticles, those having an atomic scale of 1000 nm can be preferably applied, those having an average particle diameter of 3 to 300 nm are preferable, and those having an average particle diameter of 5 to 100 nm are more preferably used. Among these, silver nanoparticles having an average particle diameter of 3 nm to 100 nm are particularly preferable.

  In the first aspect, a combination of materials having different absorbances can be selected from these materials and used for the source electrode 11 and the drain electrode 12, respectively.

  In the first embodiment, a material other than the conductive material (for example, a light absorbing material or a light reflecting material) can be mixed with the conductive material so that the absorbance of the source electrode 11 and the drain electrode 12 is different. .

  FIG. 3 is a plan view for explaining an example of the second aspect of the method for forming a semiconductor film of the present invention.

  In the second aspect, an asymmetric temperature distribution is formed depending on the configuration (particularly the arrangement state) of the light absorption heating element in the base material 1. Here, the source electrode 11 and the drain electrode 12 are used as the light absorption heating element.

  In the second mode, the source electrode 11 and the drain electrode 12 have a difference in heat generation area with respect to the irradiation light.

  Therefore, when the source electrode 11 and the drain electrode 12 are irradiated with light, a difference is generated in the generation amount of thermal energy converted from the light energy of the irradiated light.

  Thereby, when the ink 2 is dried by light irradiation, the temperature distribution of the semiconductor ink 2 in the channel region 13 can be asymmetric in the SD direction.

  In the example of FIG. 3, the case where the difference in the formation length in the SD direction of the source electrode 11 and the drain electrode 12 is shown as a difference in the heat generation area, but the present invention is not limited to this example.

  For example, as shown in FIG. 4, a difference may be provided in the heat generation area by different formation lengths of the source electrode 11 and the drain electrode 12 in the direction orthogonal to the SD direction.

  In the example of FIGS. 3 and 4, the case where the source electrode 11 and the drain electrode 12 are rectangular when viewed in plan has been described, but the present invention is not limited to this, and various shapes can be given.

  In the example of FIG. 5, the drain electrode 12 is provided in an arc shape so as to surround the source electrode 11 provided in a circular shape. As described above, it is also preferable to form an asymmetric temperature distribution by providing the source electrode 11 and the drain electrode 12 with different shapes.

  By the way, in the example of FIG. 5, the SD direction (arrow direction in the figure) is formed in multiple directions. That is, in one aspect, the SD direction is not necessarily one direction, and may be multi-directional as in the example of FIG. When the SD direction is formed in multiple directions, it is sufficient that an asymmetric temperature distribution is formed in at least one direction, and it is preferable that an asymmetric temperature distribution is formed in all directions.

  In the example of FIG. 6, a hole 110 is provided in the source electrode 11. The hole 110 is provided so as to penetrate the electrode. Therefore, the base on which the electrode is provided is viewed from the hole 110. By providing the hole 110, the heat generation area of the electrode is reduced.

  In the example of FIG. 6A, when the hole 110 is ignored, the heat generation area of the source electrode 11 and the heat generation area of the drain electrode 12 are equal, but by providing the hole 110, the heat generation area of the source electrode 11 is The heat generation area of the drain electrode 12 is smaller. For example, when the hole 110 is ignored and the heat generation area of the source electrode 11 is larger than the heat generation area of the drain electrode, the hole 110 is provided, so that the heat generation area of the source electrode 11 is reduced. It may be smaller than the heat generation area of the electrode 12.

  Further, as shown in FIG. 6B, when the hole 110 is ignored and the heat generation area of the source electrode 11 is smaller than the heat generation area of the drain electrode 12, the hole 110 is provided. The heat generation area may be smaller than the heat generation area of the drain electrode 12.

  The number of holes 110 provided in the source electrode 11 may be plural as shown in FIG. 6A, or may be one as shown in FIG. 6B. Thereby, it becomes easy to ensure a larger heating area difference. Moreover, the shape of the hole 110 is not particularly limited, and can be configured by appropriately combining one or more of a circular shape, a polygonal shape, a linear shape, and the like.

  The hole 110 described above is not limited to being provided in the source electrode 11. For example, when the heat generation area of the drain electrode 12 is made smaller than the heat generation area of the source electrode, a hole can be provided in the drain electrode 12.

  In the second embodiment, the heat generation area of the source electrode 11 and the drain electrode 12 may be larger for the source electrode 11 or for the drain electrode 12.

  In the above description, the case where the source electrode 11 and the drain electrode 12 are used as the light absorption heating element has been described. However, a member other than the source electrode 11 and the drain electrode 12 (for example, a gate electrode) is used and this is used in the SD direction. It is also preferable to arrange them asymmetrically and use them as light-absorbing heating elements.

  FIG. 7 is a plan view for explaining an example of the third aspect of the method for forming a semiconductor film of the present invention.

  In the third aspect, an asymmetric temperature distribution is formed by the configuration of the light absorption heating element in the substrate 1. At this time, the dummy heat generating pattern 14 is provided on the base material 1 as a light absorbing heat generating element. The dummy heat generation pattern 14 is provided for the purpose of forming an asymmetric temperature distribution, and can be distinguished from a member for driving a transistor such as the source electrode 11, the drain electrode 12, and the gate electrode.

  In the illustrated example, the dummy heat generation pattern 14 is provided at a position that is biased toward the drain electrode 12 side than the source electrode 11. More specifically, a total of two dummy heat generation patterns 14 are provided, one on each side of the drain electrode 12 as viewed from the SD direction.

  Therefore, when irradiated with light, more heat energy is generated on the drain electrode 12 side where the dummy heat generation pattern 14 is unevenly distributed.

  Thereby, when the ink 2 is dried by light irradiation, the temperature distribution of the semiconductor ink 2 in the channel region 13 can be asymmetric in the SD direction.

  In the above example, the dummy heating pattern 14 is unevenly distributed on the drain electrode 12 side. However, the present invention is not limited to this. For example, it is preferable that the dummy heat generation pattern 14 be unevenly distributed on the source electrode 11 side.

  In the above example, the case where two dummy heat generation patterns 14 are provided on the substrate 1 has been described, but the present invention is not limited to this, and one or two or more can be provided as appropriate.

  The dummy heat generation pattern 14 is made of, for example, a material that can absorb illuminance light and convert it into heat. Such a material is an organic or inorganic material, and preferably absorbs light in part or all of the light source spectrum. What has 0.01-3 is suitable.

  The absorbance of the dummy heating pattern 14 is preferably higher than the absorbance of the lower ground of the substrate 1 on which the dummy heating pattern 14 is provided. Here, the base surface is a surface of a member disposed adjacent to the back side of the dummy heat generation pattern 14 when viewed from the light irradiation direction when the ink 2 is dried.

  As another embodiment, a dummy low heat generation pattern having an absorbance lower than that of the lower ground of the substrate 1 on which the dummy low heat generation pattern is formed can be used. If such a dummy low heat generation pattern is used, an asymmetric temperature distribution can be formed by reducing the generated heat energy unevenly in the SD direction.

  In the embodiment using the light absorption heating element described above, the ink 2 does not necessarily need to be applied so as to be in contact with the light absorption heating element, but may be applied so as not to contact the light absorption heating element. Good. When the light absorption heating element and the ink 2 are not in contact with each other, the distance from the light absorption heating element to the ink 2 application region is 2 μm from the viewpoint of suitably conducting the heat energy from the light absorption heating element to the ink 2. Or less, more preferably 1 μm or less.

  The light-absorbing heating element does not necessarily have to be exposed on the surface of the base material 1 and may be embedded in the base material 1 as long as the irradiation light reaches when the ink 2 is dried. In this case, the distance from the surface of the substrate 1 to the light absorption heating element is preferably 2 μm or less, and more preferably 1 μm or less.

  FIG. 8 is a plan view for explaining an example of the fourth aspect of the method for forming a semiconductor film of the present invention.

  In a 4th aspect, asymmetric temperature distribution is formed by making light irradiation into pattern exposure.

  In the illustrated example, the exposure area of the irradiation light for drying the ink 2 is formed on a wider area on the drain electrode 12 side than on the source electrode 11 side, that is, biased toward the drain electrode 12 side. .

  Therefore, when irradiated with light, more thermal energy is generated on the drain electrode 12 side than on the source electrode 11 side.

  Thereby, when the ink 2 is dried by light irradiation, the temperature distribution of the semiconductor ink 2 in the channel region 13 can be asymmetric in the SD direction.

  In the above example, the case where the exposure region of the irradiation light for drying the ink 2 is biased toward the drain electrode 12 side rather than the source electrode 11 side is shown, but the present invention is not limited to this. It may be biased toward the source electrode 11 side rather than the side.

  The method for performing pattern exposure is not particularly limited, and for example, a method using laser light or a method using a photomask can be preferably used.

  The areas other than the exposure area may not be exposed, or may be exposed with light having an illuminance weaker than that of the exposure area.

  In another embodiment of the present invention, when the ink is dried to form a semiconductor film, it is preferable to shift the final drying region of the ink by light irradiation.

  The “final drying region” means a region where drying is finally completed in the process of proceeding to dry ink.

  FIG. 9 is a diagram illustrating the final drying region of ink.

  As shown in FIG. 9A, the drying of the ink 2 on the substrate 1 does not proceed equally over the entire ink 2, but basically, the edge of the ink 2 is sequentially advanced from the edge toward the center. Since it proceeds, if it is normal drying without light irradiation, a final drying area appears at a position F in the center of the ink.

  On the other hand, as shown in FIG. 9B, by performing light irradiation, the final dry region appearing at the position F when the light irradiation is not performed is shifted to a position F ′ different from the position F. be able to. As a specific method for causing such a shift in the final dry region, it is possible to use a method for forming the above-described asymmetric temperature distribution formed by light irradiation.

  In the semiconductor film obtained by drying the ink 2, the crystal growth direction from the multi-direction becomes more irregular as the closer to the final drying region, the crystal orientation becomes relatively irregular.

  Therefore, when the final dry region is not shifted, for example, as shown in FIG. 9A, in the semiconductor film 3 obtained after drying, the region G (shaded portion in the drawing) in which the crystal growth direction is aligned is arranged. Since there is a region (near position F) in which the crystal growth direction is disturbed in the center, the region G in which the crystal growth direction is arranged is continuously formed as one unit (a group of squares in the illustrated example) H over a wide area. There is a limit in forming it.

  On the other hand, by shifting the final dry region of the ink 2 by light irradiation, as shown in FIG. 9B, in the semiconductor film 3 obtained after drying, the region G in which the crystal growth direction is aligned is formed. As a single unit (in the illustrated example, a rectangular unit) H, it can be continuously formed in a wider area.

  As described above, in the semiconductor film 3, if a region in which the crystal growth direction is arranged can be continuously formed as a single unit H in a wide area, a region in which the crystal growth direction is arranged can be easily captured on the channel. It becomes easy to reduce the proportion of the region in which the crystal growth direction is disturbed and increase the proportion of the region in which the crystal growth direction is aligned. In addition, the drying of the ink 2 proceeds anisotropically so as to follow the shifted final drying region, so that the crystal growth direction in the semiconductor film 3 becomes more uniform.

  As a result, the obtained semiconductor film has improved homogeneity on the channel and can contribute to realization of high mobility in the organic thin film transistor. From another point of view, it is also possible to favorably improve the yield in obtaining one unitary H in which the crystal growth direction is aligned from the ink 2 by shifting the final dry region by light irradiation.

  In a mode in which the final drying region of ink is shifted by light irradiation, ink is applied in advance across the inside and outside of the channel region, and the final drying region of ink is shifted from the inside of the channel region to the outside of the channel region by light irradiation. It is also preferable to make it.

  In still another embodiment of the present invention, when the ink is dried to form the semiconductor film, a temperature gradient is formed in the ink by light irradiation, and the temperature gradient is changed from the high temperature side to the low temperature side. It is preferable to direct the direction of the drying of the ink.

  As described above, the ink drying direction basically progresses sequentially from the edge of the ink toward the center, but at this time, the surface condition of the substrate also affects the direction of drying drying. Can give. For example, due to the influence of impurities present on the substrate or the interface between different materials on the substrate such as between the electrode and the insulating film, the direction of ink drying tends to change locally locally. On the other hand, if the temperature gradient formed in the ink by light irradiation is used, the direction of the drying of the ink is directed from the high temperature side to the low temperature side so as to cancel out the influence of impurities and foreign material interfaces. Therefore, local changes in the direction of drying are reduced, and the crystal growth direction can be adjusted appropriately. Such an effect of directing the direction of ink drying can be achieved independently of the above-described effect of shifting the final drying region due to its action mechanism.

  Preferably, such a temperature gradient is formed in the ink in the channel region. Further, such a temperature gradient can be suitably formed by giving the above-described asymmetric temperature distribution to the ink.

  Most preferably, when the ink is dried, both the shift of the final drying area and the direction of the direction of ink drying occur, and the synergistic action of these causes the crystal growth direction to be adjusted more appropriately. The homogeneity of the semiconductor film can be further improved.

  Hereinafter, the present invention will be described in more detail with reference to an example of forming a thin film transistor.

  FIG. 10 is an explanatory diagram showing an example of forming a bottom gate / bottom contact type thin film transistor.

  First, as shown in FIG. 10A, after forming the gate electrode 16 on the support 15, the insulating layer 17 is formed, and the source electrode 11 and the drain electrode 12 are formed thereon, respectively. Prepare 1

  Next, as shown in FIG. 10B, the ink 2 containing a semiconductor material is applied onto the channel 13 of the base material 1.

  Next, as shown in FIG. 10C, the surface 2 of the substrate 1 is irradiated with light to form the asymmetric temperature distribution described above, and the ink 2 applied to the substrate 1 is dried. As shown in FIG. 10D, a semiconductor film 3 containing a semiconductor material is formed, and a bottom gate / bottom contact type thin film transistor 4 is obtained.

  In the example of FIG. 10, since the source electrode 11 and the drain electrode 12 are already formed when applying the ink 2 containing the semiconductor material on the channel 13, the source electrode 11 and the drain are used as the light absorption heating element described above. The electrode 12 can be used suitably.

  Of course, members (for example, gate electrodes) other than the source electrode 11 and the drain electrode 12 are arranged asymmetrically in the SD direction, or the dummy heating pattern 14 described above is provided on the substrate 1 prior to the application of the ink 2. These can also be used as a light absorption heating element.

  Furthermore, an asymmetric temperature distribution can be formed depending on the irradiation mode of light irradiation, such as the pattern exposure described above.

  FIG. 11 is an explanatory diagram showing an example of forming a bottom gate / top contact type thin film transistor.

  First, as shown in FIG. 11A, a substrate 1 is prepared in which a gate electrode 16 is formed on a support 15 and an insulating layer 17 is formed on the gate electrode 16 and the support 15. In this example, the source electrode 11 and the drain electrode 12 are not formed, but the channel 13 is defined in relation to the positions of the source electrode 11 and the drain electrode 12 to be formed later.

  Next, as shown in FIG. 11B, the ink 2 containing a semiconductor material is applied onto the channel 13 of the base material 1.

  Next, as shown in FIG. 11 (c), the surface of the base material 1 is irradiated with light to form the asymmetric temperature distribution described above, and the ink 2 applied to the base material 1 is dried. As shown in FIG. 11D, the semiconductor film 3 is formed.

  Next, as shown in FIG. 11E, the bottom gate / top contact type thin film transistor 4 is obtained by forming the source electrode 11 and the drain electrode 12 so as to be in contact with the semiconductor film 3.

  In the example of FIG. 11, since the source electrode 11 and the drain electrode 12 are not formed when the ink 2 is applied, members other than the source electrode 11 and the drain electrode 12 (for example, the gate electrode 16) are asymmetric in the SD direction. These can be used as a light-absorbing heating element by arranging or providing the above-described dummy heating pattern 14 on the substrate 1 prior to application of the ink 2.

  Furthermore, an asymmetric temperature distribution can be formed depending on the irradiation mode of light irradiation, such as the pattern exposure described above.

  FIG. 12 is an explanatory diagram showing an example of forming a top gate / bottom contact type thin film transistor.

  First, as shown in FIG. 12A, the base material 1 formed by forming the source electrode 11 and the drain electrode 12 on the support 15 is facilitated.

  Next, as shown in FIG. 12B, the ink 2 containing a semiconductor material is applied onto the channel 13 of the base material 1.

  Next, as shown in FIG. 12C, the surface of the base material 1 is irradiated with light to form the asymmetric temperature distribution described above, and the ink 2 applied to the base material 1 is dried. As shown in FIG. 12D, the semiconductor film 3 is formed.

  Next, as shown in FIG. 12E, the top gate / bottom contact type thin film transistor 4 is obtained by forming the insulating layer 17 on the semiconductor film 3 and further forming the gate electrode 16 thereon. .

  In the example of FIG. 12, since the source electrode 11 and the drain electrode 12 are already formed when the ink 2 containing the semiconductor material is applied to the channel 13, the source electrode 11 and the drain are used as the light absorption heating element described above. The electrode 12 can be used suitably.

  Of course, members other than the source electrode 11 and the drain electrode 12 are asymmetrically arranged in the SD direction, or the above-described dummy heat generation pattern 14 is provided on the substrate 1 prior to the application of the ink 2 to absorb the light. It can also be used as a heating element.

  Furthermore, an asymmetric temperature distribution can be formed depending on the irradiation mode of light irradiation, such as the pattern exposure described above.

  FIG. 13 is an explanatory diagram showing an example of forming a top gate / top contact type thin film transistor.

  First, as shown in FIG. 13A, a base material 1 made of a support 15 is prepared. In this example, the source electrode 11 and the drain electrode 12 are not formed, but the channel 13 is defined in relation to the positions of the source electrode 11 and the drain electrode 12 to be formed later.

  Next, as shown in FIG. 13B, the ink 2 containing a semiconductor material is applied onto the channel 13 of the base material 1.

  Next, as shown in FIG. 13C, the surface of the base material 1 is irradiated with light to form the above-described asymmetric temperature distribution, and the ink 2 applied to the base material 1 is dried. As shown in FIG. 13D, the semiconductor film 3 is formed.

  Next, as shown in FIG. 13E, a source electrode 11 and a drain electrode 12 are formed so as to be in contact with the semiconductor film 3, and a gate electrode 16 is sequentially formed thereon via an insulating layer 17. A top gate / top contact type thin film transistor 4 is obtained.

  In the example of FIG. 13, since the source electrode 11 and the drain electrode 12 are not formed when the ink 2 is applied, members other than the source electrode 11 and the drain electrode 12 are arranged asymmetrically in the SD direction, or the ink 2 Prior to the application, the above-described dummy heat generation pattern 14 is provided on the base material 1, and these can be used as a light absorption heat generating body.

  Furthermore, an asymmetric temperature distribution can be formed depending on the irradiation mode of light irradiation, such as the pattern exposure described above.

  Examples of the material constituting the support 15 include glass, plastic (polyethylene, polypropylene, acrylic, polyester, polyamide, etc.), metal (copper, nickel, aluminum, iron, etc., or an alloy), ceramic, and the like. It may be a single layer or a laminate of two or more layers selected from these.

  Although the material which comprises the gate electrode 16 is not specifically limited, What was illustrated by description of the source electrode 11 and the drain electrode 12 can be used preferably.

  The material constituting the insulating layer 17 is not particularly limited as long as it is an insulating material, and examples thereof include inorganic oxides and organic compounds.

  Inorganic oxides include silicon oxide, aluminum oxide, tantalum oxide, titanium oxide, tin oxide, vanadium oxide, barium strontium titanate, barium zirconate titanate, lead zirconate titanate, lead lanthanum titanate, strontium titanate, Examples thereof include barium titanate, barium magnesium fluoride, bismuth titanate, strontium bismuth titanate, strontium bismuth tantalate, bismuth tantalate niobate, and yttrium trioxide.

  Examples of the organic compound include polyimide, polyamide, polyester, polyacrylate, photo-curing polymer of photo radical polymerization system, photo cationic polymerization system, copolymer containing acrylonitrile component, polyvinyl phenol, polyvinyl alcohol, novolac resin, and the like. It is done.

  In the case of forming a thin film transistor according to the present invention, the structure of the thin film transistor is not limited to the above example, and can be applied to thin film transistors having various structures. In particular, it can be suitably used for an organic thin film transistor formed using an organic semiconductor material as a semiconductor material.

  In the light irradiation used for drying the ink 2, the irradiated light is not particularly limited, and those that can accelerate the drying of the ink 2 can be preferably used, and can be converted into heat such as ultraviolet rays, visible light, infrared rays, and microwaves. Light can be used as appropriate. As a method for directly heating the channel, a xenon lamp having a wide spectrum from visible light to infrared is preferable, and even when a xenon lamp is used, particularly high illumination light is preferable. By using high illuminance light, the above-described asymmetric temperature distribution can be suitably formed in a state where ink flow is suppressed.

The high illuminance light is preferably light having an illuminance of at least 100 mW / cm ² on the surface of the substrate 1, and such light is not particularly limited. For example, laser light or flash Light etc. can be illustrated preferably.

  The illuminance on the surface of the substrate 1 refers to the entire emission wavelength, and is a maximum value of light emission power conversion value or a value measured by an exposure illuminance measuring machine as appropriate.

The laser beam is not particularly limited, but a solid laser such as a ruby laser, a YAG laser, or a glass laser; He—Ne laser, Ar ion laser, Kr ion laser, CO ₂ laser, CO laser, He—Cd Gas lasers such as laser, N ₂ laser, and excimer laser; semiconductor lasers such as InGaP laser, AlGaAs laser, GaAsP laser, InGaAs laser, InAsP laser, CdSnP ₂ laser, and GaSb laser; It is possible to appropriately stop the beam and perform scanning exposure according to the purpose. In order to obtain high resolution by exposure with laser light, electromagnetic waves that can narrow the energy application area, particularly ultraviolet light, visible light, and infrared light with a wavelength of 1 nm to 1 mm are preferable. As such a laser light source, ruby laser is used. Solid lasers such as YAG laser and glass laser; He—Ne laser, Ar ion laser, Kr ion laser, CO ₂ laser, CO laser, He—Cd laser, N ₂ laser, excimer laser and other gas lasers; InGaP laser, Examples thereof include semiconductor lasers such as AlGaAs laser, GaAsP laser, InGaAs laser, InAsP laser, CdSnP ₂ laser, and GaSb laser; chemical laser, dye laser, and the like.

  The flash light is not particularly limited, but a flash light by a xenon lamp, a halogen lamp, a mercury lamp, or the like can be preferably exemplified, and these exposures may be performed on the entire surface or through a photomask. You may go.

  When the high illuminance light is flash light, it is also preferable to continuously irradiate the surface of the substrate 1 with the flash light a plurality of times. The irradiation conditions are preferably set as appropriate in accordance with the solvent type of the ink 2, the amount of the ink 2 applied to the surface of the substrate 1, and the like. For example, when performing multiple irradiations once, Is preferably in the range of 1 microsecond to 2 milliseconds, and an intermittent time (no irradiation time or low output irradiation time) of 0.5 milliseconds to 100 milliseconds is preferably provided between the irradiation times. Moreover, it is preferable that the frequency | count of irradiation is the range of 10-30000 times.

  In this way, by intermittently performing exposure with high illuminance, the ink 2 applied on the substrate 1 repeats from room temperature → higher temperature → lower temperature → higher temperature → lower temperature →. A heating history different from simple heating significantly contributes to suitably forming the above-described asymmetric temperature distribution while suppressing ink flow.

  The light irradiation range in the light irradiation used for drying the ink 2 is set so as to irradiate at least a part of the surface of the substrate 1. In the embodiment using the light absorption heating element, the irradiation range is set so that the light absorption heating element is included in the irradiation range.

  Further, the light irradiation range may include the entire ink 2 within the range, or may include only a part of the ink 2 within the range, or may be set so that the ink 2 is out of the range. Also good. It is preferable that at least a part of the ink 2 is included in the irradiation range, and it is more preferable that the entire ink 2 is included in the irradiation range.

  The semiconductor material contained in the ink 2 is not particularly limited, but is preferably an organic semiconductor material.

  Examples of the organic semiconductor material include a high-molecular organic semiconductor material having a molecular weight of 10,000 or more, and a low-molecular organic semiconductor material having a molecular weight of less than 10,000.

The compound used as the high-molecular organic semiconductor material is not particularly limited. For example, polythiophene, a compound having a thiophene ring in the main chain, or a derivative in which a side chain having an alkyl group or the like is added to these compounds, etc. A specific example is Poly [(9,9-di-n-octylfluorenyl-2,7-diyl) -alt-2,2′-bithiophene-5,5′-diyl)] (abbreviation F8T2). Poly [bis (3-dodecyl-2-thienyl) -2,2′-dithiophene-5,5′-diyl] (abbreviated as PQT-12), Poly [2,5-bis (3-dodecylthiophen-2-yl). ) thieno [3,2-b] thiophene ] ( abbreviation PBTTT-C _{2), Poly [2,5-bis} (3-tetradecylthiophen-2-yl) thieno [3,2-b] thiophene] ( abbreviation _{PBTTT-C 14), Poly [} 2,5-bis (3-hexadecylthiophen-2 -yl) thieno [3,2-b] thiophene] ( abbreviation _{PBTTT-C 16)} or the like can be preferably exemplified.

  The compound used as the low-molecular organic semiconductor material is not particularly limited.For example, naphthalene, anthracene, tetracene, rubrene, pentacene, benzopentacene, dibenzopentacene, tetrabenzopentacene, naphthopentacene, hexacene, heptacene, nanoacene, fluorene, Fluoranthene, phenanthrene, chrysene, triphenylene, tetraphen, tetracene, picene, flumilen, tetraphen, pyrene, antanthrene, peropyrene, coronene, benzocoronene, dibenzocoronene, hexabenzocoronene, benzodicoronene, perylene, terylene, diperylene, quaterylene, trinaphthylene, heptaphene, ovalene , Rubicene, violanthrone, isoviolanthrone, circumcamanthracene, bisanthene, zestrene Heputazesuren, Piransu, kekulene, Torakisen, fullerene (e.g., C60, C70, C60-PCBM, C70-PCBM, etc.) derivatives and these compounds.

  The compound used as the low-molecular organic semiconductor material may be a compound containing a hetero atom. Examples of the compound containing a hetero atom include benzodithiophene, naphthodithiophene, anthradithiophene, tetradithiophene, pentadithiophene, hexadithiophene, dibenzothiophene, benzothienobenzothiophene, dinaphthothienothiophene, thienothiophene, Dithienothiophene, tetrathienoacene, pentathienoacene, dibenzofuran, carbazole, dibenzosilole, benzodithiaazole, naphthodithiaazole, anthradithiazole, tetradithiaazole, pentadithiaazole, hexadithiaazole, thia Zorothiazole, tetrathiafulvalene, dibenzothiafulvalene, dithiophenthiafulvalene, tetracyanoquinodimethane, tetracyanonaphthoquinodimethane, naphthalenetetra Carboxymethyl Rick diimide, and derivatives of perylenetetracarboxylic carboxylic diimide and these compounds. In addition, compounds containing metals such as phthalocyanine, porphyrin, tetrabenzoporphyrin, triphenylamine, and derivatives of these compounds are also included in compounds containing heteroatoms. Heteroatoms of compounds containing the exemplified heteroatoms may be replaced with other heteroatoms.

  Examples of derivatives of these compounds include halogen atoms, alkyl groups, aliphatic unsaturated hydrocarbon groups, aryl groups, heteroaryl groups, alkoxy groups, amino groups, carbonyl groups, nitro groups, hydroxyl groups, cyano groups, and aryl groups. Examples thereof include a compound having a substituent selected from an alkyl group, an aryloxy group, a heteroarylalkyl group, a heteroaryloxy group, an alkylsilyl group and the like, and a quinone derivative of the compound.

  Among these, when a low molecular weight compound having a relatively large influence on crystallinity due to drying conditions and having a molecular weight of 8000 or less, preferably 5000 or less, more preferably 2000 or less, and most preferably 1000 or less is used. The effect becomes remarkable. In particular, a compound having a plate-like π skeleton portion in which 3 to 10 aromatic rings are condensed with each other, a compound having a crystal structure having a π stack structure, and the like are preferable. Moreover, the compound which has 1 or 2 or more of substituents containing a phenyl group or an alkyl group in pi frame | skeleton part can also be used suitably. Particularly preferable examples of such a compound include benzothienobenzothiophene, dinaphthothienothiophene and the like, and derivatives obtained by substituting one or more substituents containing a phenyl group or an alkyl group in the π skeleton.

  The solvent that the ink 2 can contain is not particularly limited, and a solvent that can contain the above-described semiconductor material in a dispersed or dissolved state can be suitably used. If a specific example is given, organic solvents, such as hydrocarbon type, alcohol type, ether type, ester type, ketone type, glycol ether type, or water can be illustrated preferably, and these 1 type or 2 types or more are mixed. Can be used.

  The ink 2 contains, for example, a material that serves as an acceptor that accepts electrons or a material that serves as a donor that serves as an electron donor, together with a semiconductor material, and a so-called doping treatment is performed on the resulting semiconductor film. You may be made to do.

  Furthermore, the ink 2 is suitable for the purpose of adjusting dispersibility or solubility in a solvent such as a semiconductor material, or for application to an ink application method such as an ink jet method, as long as the effects of the invention are not impaired. For this purpose, various additives such as a surfactant can be added. Note that it is also preferable not to add an additive from the viewpoint of eliminating the influence on the characteristics of the semiconductor film.

  The viscosity of the ink 2 is not particularly limited, but is preferably a low-viscosity ink. Specifically, the viscosity is preferably in the range of 1 mP · s to 30 mPa · s, and is preferably 1 mP · s to 10 mP. -More preferably, it is in the range of s or less. It is preferable that the light irradiation is performed within a period in which the ink 2 has a viscosity within such a range. The viscosity is a value measured using a rotary viscometer, a vibration viscometer, or the like under a viscosity measurement condition suitable for the above-described viscosity range measurement under a shear rate of about 10 to 1000-1 s.

  The method for applying the ink 2 on the substrate 1 is not particularly limited, but a printing method or the like is preferable. As a printing method, a generally known method can be used, and an inkjet method, a screen printing method, a relief printing method, an intaglio printing method, an offset printing method, a flexographic printing method, etc. can be preferably exemplified, and an inkjet method in particular. Is preferred. As the ink jet method, for example, a known method such as an on-demand type such as a piezo method or a bubble jet (registered trademark) method or a continuous jet type ink jet method such as an electrostatic suction method can be used.

  In addition, the application of ink 2 is not limited to the case of applying pre-prepared ink 2, and a plurality of ink components are individually applied on substrate 1, and these are mixed on substrate 1. The ink 2 may be applied as a result of the preparation of the ink 2. For example, a method of preparing a desired ink 2 by mixing two or more kinds of inks individually applied by an ink jet method or the like on the substrate 1 can be mentioned.

  Alternatively, the ink 2 containing the semiconductor material may be applied by applying the ink containing the precursor of the semiconductor material on the substrate 1 and then converting the precursor into the semiconductor material by reaction.

  The diameter of the ink 2 (wet film) applied on the substrate 1 is not particularly limited, but is preferably in the range of 5 μm to 1000 μm. The thickness of the semiconductor film 3 obtained by drying the ink 2 is not particularly limited, but is preferably in the range of 10 nm to 3 μm.

  In the present invention, it is also preferable to blow air around the ink 2 during light irradiation. Thereby, the solvent vapor | steam produced with the drying of the ink 2 by light irradiation can be removed from the vicinity of the said ink 2, and the film-forming of a semiconductor film can be stabilized. In particular, when irradiating with high illuminance light, the drying speed of the ink 2 is fast, and the solvent vapor is rapidly generated along with this, so the effect of removing this by blowing is great.

  The timing of starting the blowing is preferably after applying the ink 2 to the substrate 1 and before or during light irradiation. In addition, when the application method of the ink 2 is not easily affected by the blowing, the blowing may be performed before the ink 2 is applied to the substrate 1. The air blowing is preferably continued at least during the light irradiation and is continued until the light irradiation is completed.

  The forming apparatus for forming the semiconductor film is not particularly limited, but a mechanism for applying the ink 2 onto the substrate 1, and the ink 2 is dried by irradiating the surface of the substrate 1 before the ink 2 is dried. What has a mechanism (it may be called a light irradiation means) can be used preferably.

  FIG. 14 is a principal side schematic side view showing an example of a forming apparatus for forming a semiconductor film, and FIG. 15 is a plan view thereof.

  The forming apparatus shown in FIG. 14 and FIG. 15 incorporates a light irradiation means in the configuration of a normal ink jet recording apparatus (mechanism for applying ink 2 on a substrate 1).

  14 and 15, the thin film forming apparatus 5 includes a carriage 51 that can be moved relative to the substrate 1 by a driving unit (not shown). The carriage 51 includes an inkjet head 52 and a surface of the substrate 1. The light irradiation means 53 which irradiates light is mounted. Here, it is assumed that the carriage 51 moves in the left direction (arrow direction) in the figure with respect to the base material 1 along a guide rail (not shown).

  Here, the light irradiation means 53 is equipped with two xenon flash lamps 53a and 53b, and one xenon flash lamp 53a is arranged closer to the inkjet head 52 side (upstream in the movement direction) than the other xenon flash lamp 53b. Has been. Reference numerals 531a and 531b denote optical filters provided in the xenon flash lamps 53a and 53b.

  Further, on the downstream side of the carriage 51 in the traveling direction from the ink jet head 52, an air supply means 54 and an exhaust means 55 are provided before and after the light irradiation means 53, respectively. The air supply from the air supply means 54 is exhausted by the exhaust means 55, so that a blast of laminar flow can be formed between the light irradiation means 53 and the substrate surface. The air supply means 54 and the exhaust means 55 can each be constituted by a fan or the like. Reference numeral 56 denotes a rectifying unit for promoting the laminar flow of the air flow, and is provided over a region from the air supply means 54 to the exhaust means 55.

  When forming a semiconductor film using the forming apparatus 5 having the configuration described above, from the inkjet head 52 of the carriage 51 that moves relative to the base material 1 in the left direction (the arrow direction in the figure), Ink 2 is applied to the surface of the substrate 1.

  Thereafter, the carriage 51 further moves in the left direction, so that the ink 2 applied to the surface of the substrate 1 is irradiated with light from the xenon flash lamps 53a and 53b, and has the above-described asymmetric temperature distribution. To be a semiconductor film 3. The solvent vapor generated with the drying is suitably removed by the air generated by the air supply means 54, the exhaust means 55, and the rectifying unit 56, and the drying is further promoted.

  In the above description, the case where the configuration of the ink jet recording apparatus is used as the mechanism for applying ink onto the base material has been described. However, the present invention is not limited to this, and any mechanism can be used.

  In the above description, the structure described for one embodiment can be combined with another embodiment as appropriate.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Example 1)
In Example 1, a transistor (thin film transistor; TFT) having the electrode shape (the shape of the gate electrode 16, the source electrode 11, and the drain electrode 12) shown in FIG. 16 was manufactured by the following method.

  On the PEN film substrate having a thickness of 100 μm that had been flattened, the Ag nano-ink was printed by the reverse printing method to form the gate electrode 16 and baked at 180 ° C. for 30 minutes.

  Next, an organic insulating film material was applied on the gate electrode 16 by a die coater, dried, and then fired at 180 ° C. for 30 minutes to form a gate insulating film (not shown).

  Next, the source electrode 11 and the drain electrode 12 were formed on the gate insulating film by the same reverse printing method, material, and baking method as the gate electrode 16. The channel 13 has a channel length of 10 μm and a channel width of 100 μm.

  As illustrated, the drain electrode 12 has a larger pad area than the source electrode 11, and is asymmetric in the SD direction.

  Next, PFBT (pentafluorobenzenethiol) was applied as a SAM film on the electrode to the source electrode 11 and the drain electrode 12, and a charge injection layer was provided.

  Next, 10 drops of organic semiconductor ink (diphenylbenzothienobenzothiophene-based, 1 wt% mesitylene solution) on the channel 13 at a pitch of 10 microns along the longitudinal direction of the channel 13 by an inkjet method (the volume per drop is 4 pL) was dropped in one scan from the lower direction to the upper direction in the figure (the droplet ejection position was indicated by dots in the figure), and 10 seconds after forming the coating film of ink 2. Irradiation / heating with a xenon flash lamp was performed for 2 seconds.

Heating with a xenon flash lamp uses a Hamamatsu Photonics 60W xenon flash lamp L7684, voltage 1000 V (input voltage 60 W), emission frequency 100 Hz, exposure surface output 1 W / 50 mmφ, pulse width 2.1 μs, (illuminance on substrate surface; Equivalent to 400 mW / cm ² ). In order to avoid the influence of the lamp on the semiconductor and the organic insulating film, the ultraviolet component of 420 nm or less is cut by a filter.

  Next, heat treatment was performed at 80 ° C. for 10 minutes to form a bottom gate bottom contact type TFT.

<Evaluation method>
The Id-Vg characteristics of the obtained TFT were measured, and the carrier mobility average, mobility variation, and Vg-30 V on-current variation were determined from the measured data. In the characteristic evaluation, the average and variation of 25 elements were calculated.

(Comparative Example 1)
In Example 1, a TFT was prepared and evaluated in the same manner as in Example 1 except that the organic semiconductor was not naturally heated by a xenon lamp and was naturally dried.

(Example 2)
A transistor having the electrode shape (the shape of the gate electrode 16, the source electrode 11, and the drain electrode 12) illustrated in FIG. 17 was manufactured using the same method as in Example 1.

  As shown in the drawing, the source electrode 11 and the drain electrode 12 both have a comb shape, and a channel 13 is formed between alternately arranged comb teeth. The drain electrode 12 of the source electrode 11 has a large pad area, thick comb teeth (that is, a large comb tooth area), and is asymmetric in the SD direction.

  The organic semiconductor ink used in Example 1 was dropped on the droplet ejection positions indicated by dots in the drawing in a total of 360 pL in a single scan from the bottom to the top in the drawing, and the ink on the channel 13 was dropped. After the coating film 2 was formed, heat drying was performed with a xenon lamp for 50 seconds after 1 second.

  The obtained TFT was evaluated in the same manner as in Example 1.

(Comparative Example 2)
In Example 2, a TFT was prepared and evaluated in the same manner as in Example 2 except that the organic semiconductor was not naturally heated by a xenon lamp and was naturally dried.

(Example 3)
A transistor having the electrode shape (the shape of the gate electrode 16, the source electrode 11, and the drain electrode 12) illustrated in FIG. 18 was manufactured using the same method as in Example 1.

  As shown in the drawing, a drain electrode 12 is provided in an arc shape so as to surround a source electrode 11 provided in a circular shape having a hole 110. The drain electrode 12 has a larger area than the source electrode 11 and is asymmetric in the SD direction.

The organic semiconductor ink used in Example 1 was dropped on each of the droplet ejection positions indicated by dots in the drawing in a total of 160 pL in a single scan from the bottom to the top in the drawing. After the coating film 2 was formed, heat drying was performed with a xenon lamp for 30 seconds after 1 second.
The obtained TFT was evaluated in the same manner as in Example 1.

(Comparative Example 3)
In Example 3, a TFT was prepared and evaluated in the same manner as in Example 3 except that the organic semiconductor was not naturally heated by a xenon lamp and was naturally dried.

(Comparative Example 4)
A transistor having the electrode shape shown in FIG. 19 (the shape of the gate electrode 16, the source electrode 11, and the drain electrode 12) was manufactured using the same method as in Example 1.

  As shown in the figure, the source electrode 11 and the drain electrode 12 have the same area and are symmetrical in the SD direction.

The organic semiconductor ink used in Example 1 was dropped at a droplet ejection position indicated by a dot in the figure by 4 pL, a total of 40 pL in one scan from the bottom to the top in the figure, and ink 2 on the channel 13. After forming the coating film, heat drying was performed with a xenon lamp for 20 seconds after 1 second.
The obtained TFT was evaluated in the same manner as in Example 1.

(Comparative Example 5)
A transistor having the electrode shape (the shape of the gate electrode 16, the source electrode 11, and the drain electrode 12) illustrated in FIG. 20 was manufactured using the same method as in Example 1.

  As shown in the drawing, the source electrode 11 and the drain electrode 12 both have a comb shape, and a channel 13 is formed between alternately arranged comb teeth. The source electrode 11 and the drain electrode 12 have the same comb tooth thickness (that is, the same comb tooth area) and are symmetrical in the SD direction.

  The organic semiconductor ink used in Example 1 was dropped at a droplet ejection position indicated by a dot in the figure by 10 pL, a total of 160 pL from the bottom to the top in the figure by one scan, and the ink 2 on the channel 13. After the coating film was formed, it was heated and dried with a xenon lamp for 1 second after 50 seconds.

  The obtained TFT was evaluated in the same manner as in Example 1.

Example 4
In Example 4, a transistor (thin film transistor; TFT) having the electrode shape (the shape of the gate electrode 16, the source electrode 11, and the drain electrode 12) shown in FIG. 21 was manufactured by the following method. Since this TFT is a top gate type, no gate electrode has been formed yet when the organic semiconductor film is formed.

  On the PEN film substrate having a thickness of 100 μm that has been flattened, Ag nanoink is printed by the reverse printing method to form the source electrode 11 and the drain electrode 12 having the same shape as in Example 1, and then 180 ° C., Firing was performed for 30 minutes.

  Similar to the first embodiment, the drain electrode 12 has a large pad area and is asymmetric with respect to the source electrode 11.

  Next, PFBT (pentafluorobenzenethiol) was applied as a SAM film on the electrode to the source electrode 11 and the drain electrode 12, and a charge injection layer was provided.

  Next, 10 drops of organic semiconductor ink (diphenylbenzothienobenzothiophene-based, 1 wt% mesitylene solution) on the channel 13 at a pitch of 10 microns along the longitudinal direction of the channel 13 by an inkjet method (the volume per drop is 4 pL) was dropped in one scan from the lower direction to the upper direction in the figure (the droplet ejection position was indicated by dots in the figure), and after the coating film of ink 2 was formed on the channel 13, 1 After 10 seconds, irradiation and heating were performed with a xenon flash lamp for 10 seconds.

  Next, a fluorine-based organic insulating film material is applied onto the source electrode 11 and the drain electrode 12 by a spin coater, dried, and then fired at 80 ° C. for 10 minutes to form a gate insulating film (not shown). Formed.

  Next, a gate electrode (not shown) was formed on the gate insulating film by vapor deposition of a mask Au to produce a top gate type TFT.

  The obtained TFT was evaluated in the same manner as in Example 1.

(Comparative Example 6)
In Example 4, a TFT was prepared and evaluated in the same manner as in Example 4 except that the organic semiconductor was not naturally heated by a xenon lamp and was naturally dried.

  The above evaluation results are shown in Table 1.

1: Base material 11: Source electrode 12: Drain electrode 13: Channel 14: Dummy heat generation pattern 15: Support 16: Gate electrode 17: Insulating layer 2: Ink 3: Semiconductor film 4: Thin film transistor

Claims (11)

  When forming the semiconductor film by drying the ink containing the semiconductor material applied to the channel, the ink is dried so that the temperature distribution of the ink on the channel is asymmetric in the source electrode-drain electrode direction by light irradiation. A method for forming a semiconductor film, comprising:   2. The method of forming a semiconductor film according to claim 1, wherein the light absorption heating element is disposed so that the temperature distribution of the ink on the channel is asymmetric in the source electrode-drain electrode direction.   3. The method of forming a semiconductor film according to claim 2, wherein the light absorption heating element includes the source electrode and the drain electrode having different absorbances.   4. The method of forming a semiconductor film according to claim 2, wherein the light absorption heating element is constituted by the source electrode and the drain electrode having different shapes and / or areas.   The method for forming a semiconductor film according to claim 2, wherein the light absorption heating element is configured by a dummy heating pattern.   6. The method of forming a semiconductor film according to claim 1, wherein light irradiation by pattern exposure is performed so that a temperature distribution of the ink in the channel region is asymmetric in a source electrode-drain electrode direction. .   A method for forming a semiconductor film, characterized in that, when an ink containing a semiconductor material is dried to form a semiconductor film, the final drying region of the ink is shifted by light irradiation.   8. The semiconductor film formation according to claim 7, wherein the ink is applied across the inside and outside of the channel region, and the final dry region of the ink is shifted from the inside of the channel region to the outside of the channel region by the light irradiation. Method.   When a semiconductor film is formed by drying ink containing a semiconductor material, a temperature gradient is formed in the ink by light irradiation, and the drying direction of the ink is directed from the high temperature side to the low temperature side in the temperature gradient. A method for forming a semiconductor film.   10. The method of forming a semiconductor film according to claim 9, wherein the temperature gradient is formed in the ink in the channel region.   A method for manufacturing a transistor including a semiconductor film, wherein the semiconductor film is formed by the method for forming a semiconductor film according to claim 1.

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