KR100668291B1 - Fine patterning method of organics conductor film, fine patterned organics conductor film formed by the method and organic thin film transistor using the same - Google Patents

Abstract

The present invention relates to a fine patterning method of an organic conductor film, an organic thin film transistor to which a fine patterned organic conductor film formed therefrom and a fine patterned organic conductor film are applied. The fine patterning method of the organic conductor according to the present invention is to provide a method capable of fine patterning without controlling the exposure conditions and applying the lift-off method without affecting the properties of the organic material.

Organics, fine patterning, photoresist, lift off

Description

Fine patterning method of organics conductor film, fine patterned organics conductor film formed by the method and organic thin film transistor using the same}

1 is a cross-sectional view illustrating a conventional thin film transistor.

2 is a cross-sectional view illustrating an organic thin film transistor according to an exemplary embodiment of the present invention.

3 is a cross-sectional view illustrating an organic thin film transistor according to another exemplary embodiment of the present invention.

4A to 4C are flowcharts illustrating a process of manufacturing an organic thin film transistor according to an exemplary embodiment of the present invention.

5 is an optical micrograph of a patterned organic conductor film according to one embodiment of the present invention.

6 is a photograph of a PES substrate developed under exposure conditions using AZ5214 as a photosensitive film.

7 is a photograph of a PES substrate developed under exposure conditions using PFi38a as a photosensitive film.

Explanation of symbols on the main parts of the drawings

1 substrate 2 source / drain

3: activated semiconducting thin film 4: oxide insulating film

5: gate 10: plastic substrate

11 organic buffer insulating film 12 gate

13 gate insulating film 14 source / drain

15 organic semiconducting film 16 photosensitive film

The present invention relates to a fine patterning method of an organic conductor film, a fine patterned organic conductor film formed therefrom, and an organic thin film transistor using the same. More particularly, the present invention relates to a method of finely patterning an organic conductor film on a flexible substrate by controlling exposure conditions and applying a lift-off method, a fine patterned organic conductor film formed therefrom, and an organic thin film transistor using the same.

The interest in organic thin film transistors has been around since 1980, and recently, many studies are being conducted worldwide. Unlike conventional Si-TFTs using inorganic materials, organic thin film transistors use field semiconductors to form transistor channels using organic semiconductor thin films and control current flowing according to voltages applied to gates. to be.

The organic thin film transistor consists of a substrate, a buffer layer, a source / drain, an insulating film, a semiconductor film, and a gate. There are many technologies to be developed in order to use each element of the transistor as an organic material, but the patterning technology of each layer related to integration is a core technology in the commercialization of organic electronic devices.

Organics, unlike minerals, are very sensitive to heat, solvents, and light. For this reason, it is very difficult to pattern organic materials using the conventional lithography process, and in order to proceed with the conventional lithography process, baking, exposure of light, development and stripping of photoresist are performed. Should be done. As mentioned above, organics are sensitive to all these lysosomal processes and therefore require a new patterning process. In order for an organic electronic device to be used in a real electronic circuit like a conventional Si-TFT, a micro pattern having a size of about micrometer must be formed.

Therefore, there is an urgent need for the development of a new fine patterning technology capable of fine patterns and at the same time not affecting the properties of organic materials.

Therefore, the present inventors have to undergo two exposure processes of the organic conductor in the manufacture of the organic thin film transistor, and in this case, the problem between the organic material and the substrate and the damage of the organic material when the lift off method is used rather than patterning by dry etching The problem can be solved, and the lift-off method can be effectively carried out through the control of the exposure conditions, thereby discovering that it is possible to implement a micropattern of the organic conductor film and completed the present invention.

Accordingly, it is an object of the present invention to provide a fine patterning method of an organic conductor film.

It is another object of the present invention to provide a fine patterned organic conductor film.

In addition, another object of the present invention is to provide a method of manufacturing an organic thin film transistor using a fine patterned organic conductor film.

In order to achieve the above object, the present invention comprises the steps of (i) forming a photosensitive film in a desired pattern on a flexible substrate to expose and develop; (Ii) applying an organic conductor thereon; And (iii) removing the photosensitive film and the organic material thereon by a lift-off method.

In the fine patterning method according to the present invention, it is preferable to use a polyether sulfone substrate, a polyimide substrate or a polycarbonate substrate as the flexible substrate.

In the fine patterning method according to the present invention, the step of exposing and developing the photosensitive film includes (a) performing a first heat treatment on the photosensitive film; (b) exposing the heat treated film to an I-line; (c) developing; (d) secondary heat treatment.

In the exposure and development step (iii), the exposure is preferably performed under an exposure time of 100 msec (msec) to 600 msec and a depth of focus (DOF) of -0.6 or less.

In addition, in the application step (ii) of the organic conductor, it is preferable to use PEDOT / PSS (poly (3,4-ethylenedioxythiophene) / poly (styrenesulfonate)) aqueous dispersion as the organic conductor.

In the photosensitive film removing step (iii), the lift-off method is to contact the substrate coated with the organic conductor with methyl acetone to separate the photosensitive film and the organic material thereon.

In order to achieve the above another object, the present invention comprises the steps of exposing and developing a photosensitive film in a desired pattern on a flexible substrate; And applying an organic conductor thereon; And it provides a fine patterned organic conductor film prepared by a fine patterning method of the organic conductor film comprising the step of removing the photosensitive film and the organic material thereon by a lift off method.

In order to achieve the above another object, the present invention provides an organic thin film transistor to which a fine patterned organic conductor film is applied.

Hereinafter, the present invention will be described in more detail.

The present invention comprises the steps of: (i) forming a photosensitive film on a flexible substrate to expose and develop; (Ii) applying an organic conductor thereon; And (iii) removing the photosensitive film and the organic material thereon by a lift-off method.

In the step of exposing and developing a photosensitive film on the flexible substrate of the fine patterning method according to the present invention, the flexible substrate is formed before application of the photosensitive agent. It is preferable to heat-process for 15 to 24 hours at the temperature of -180 degreeC.

As the flexible substrate, a plastic substrate is mainly used, and preferably a polyether sulfone substrate, a polyimide substrate, or a polycarbonate substrate.

The organic photoresist film formed on the flexible substrate may be formed through a wet process, for example, spin coating, dipping, or printing.

The photoresist for forming the photoresist may be appropriately selected from those common in the art, and preferably AZ5214 or PFi38a may be used, which uses a novolak resin as the matrix material and Daazo as a sensitizer. Quinone is used and n-butyl acetate or xylene is suitably combined as a solvent.

The thinner the photoresist film is, the better. However, if the thickness of the organic conductor applied on the photoresist film, for example, PEDOT / PSS, is thick, the photoresist film must be thick. For example, when using AZ5214 as a photosensitizer, 2.1 µm is preferable, and in the case of PFi38a, 1.2 µm or more is preferable.

The exposing and developing step (i) comprises the steps of: (a) primary heat treatment of the photosensitive film; (b) exposing the heat treated film to an I-line; (c) developing; And (d) secondary heat treatment.

The first heat treatment step (a) is a step of removing the organic solvent of the photosensitive film to change to a solid film. In this case, the first heat treatment temperature and time is preferably heat treated at 90 to 110 ℃ for 80 to 120 seconds.

In the exposing step (b), the first heat-treated photoresist film is exposed by the I-line at a specific exposure time and a specific depth of focus (DOF). In this case, it is preferable to expose with exposure time of 100-600 m second and DOF of -0.6 or less. It can also be appropriately adjusted according to the type of photoresist, and more preferably exposed at -0.6 to -1.5 DOF for an exposure time of 100 m to 300 m sec for the AZ5214 photoresist, and 230 m to 600 m sec for the PFi38a photoresist. More preferably, it is exposed to a DOF of -1.5 or less during the exposure time.

In the developing step (c), the exposed photoresist film is developed in a developing solution at room temperature for 90 seconds to 120 seconds, and in this case, the developing step is preferably performed one or two times, and a developing agent may be generally used in this field. .

In the second heat treatment step (d) may reinforce the adhesive force of the photosensitive film and remove the remaining solvent of the developer. In this case, it is preferable that the temperature and time of the secondary heat treatment are heat treated at 110 to 120 ° C. for 60 to 30 minutes.

In addition, as the organic conductor to be applied on the photoresist, a general one in this field may be used, but preferably PEDOT may be used alone, but it is generally used in combination with PSS. Application of the organic conductors onto the substrate may be applied by a wet process, for example, spin coating, dipping or printing. Conductive polymers that can be used in addition to the PEDOT series may include polyacetylene series, polyaniline series, and the like.

After the step of applying the organic conductor is preferably heat treated for about 5 to 30 minutes at a temperature of 120 to 140 ℃.

Subsequently, the photoresist and the organic material thereon are removed by a lift-off method to form a desired pattern. The type of solution and the time immersed in the solution may be selected according to the type of photoresist film. However, when AZ5214 and PFi38a are used as the photoresist film, it is immersed in methyl acetone for 5 to 20 hours to form a desired pattern. And organic matter thereon.

Subsequently, the substrate is washed with deionized water and then dried.

The present invention also provides a fine patterned organic conductor film obtained from the above method.

The present invention also provides an organic thin film transistor using a fine patterned organic conductor film.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

1 is a cross-sectional view showing a conventional thin film transistor, FIG. 2 is a cross-sectional view showing an organic thin film transistor according to an embodiment of the present invention, Figure 3 is an organic thin film transistor according to another embodiment of the present invention 4A to 4C are process diagrams illustrating a process of manufacturing an organic thin film transistor according to an exemplary embodiment of the present invention.

Referring to FIG. 1, a conventional thin film transistor includes a substrate 1, a source / drain 2, an activation semiconductor film 3, an oxide insulating film 4, and a gate electrode 5. On the other hand, the organic thin film transistor according to the present invention has a structure as shown in Figs. That is, as shown in FIG. 2, the organic thin film transistor according to the present invention has a plastic substrate 10, an organic buffer insulating layer 11, a gate electrode 12, an organic gate insulating layer 13, a source / drain electrode 14, and an organic layer. Consisting of the semiconductor film 15 or as shown in FIG. 3, the plastic substrate 10, the organic buffer insulating film 11, the gate electrode 12, the organic gate insulating film 13, the organic semiconductor film 15 and the source / It may be composed of a drain electrode 14. In addition, it may have a different structure.

Each component of the organic thin film transistor according to the present invention may be formed by appropriately selecting materials and methods generally used in this field.

The manufacturing process of the organic thin film transistor according to the present invention is shown in FIGS. 4A to 4C, the manufacturing process of the organic thin film transistor of FIG. 2 is FIG. 4A, and the manufacturing process of the organic thin film transistor of FIG. 3 is FIG. 4B. 4C is another type of manufacturing process.

4A to 4C, the organic thin film transistor according to the present invention shows a common process for fine patterning the organic conductor film in FIGS. 4A to 4C as follows. The next step is to adapt the general methods in this field to their intended use.

One example shown in FIG. 4A is to form the organic buffer insulating film 11 on the plastic substrate 10, and to form the photoresist film 16 in a desired pattern thereon, to expose and develop (I), and then to the gate electrode thereon. (II), the photosensitive film and / or the organic material thereon are removed using a lift-off method to form (III) of FIG. 4A, and then the patterned organic conductor film 12 is formed. (IV), and then the photoresist film 16 is formed on the gate insulating film 13 in a desired pattern to expose the photoresist film. The film 14 is applied (V), and the photosensitive film and the organic material thereon are removed by a lift-off method to form (VI) of FIG. 4A, and then the organic semiconducting film 15 is formed thereon (Ⅶ). To manufacture organic thin film transistors) The.

As another example, as shown in FIG. 4B, an organic material serving as a gate electrode is formed by exposing and developing (I) the photoresist film 16 in a desired pattern on the plastic substrate 10 on which the organic buffer insulating film 11 is formed. After applying the conductor 12 (II), and then removing the photoresist film and the organic material thereon using a lift-off method to form (III) of FIG. 4B, the patterned organic conductor film 12 is protected. In order to form the gate insulating film 13 thereon (IV), the organic semiconducting film 15 is entirely coated on the gate insulating film 13 (V), and then the photosensitive film 16 is formed thereon in a desired pattern. After exposure and development, an organic conductor 14 serving as a source / drain electrode is applied thereon (VI), and the photosensitive film and the organic material thereon are removed using a lift-off method to form (b) of FIG. 4B. Organic thin film transistor Can be prepared.

As another example, as shown in FIG. 4C, an organic conductor serving as a gate electrode is formed by exposing and developing (I) the photosensitive film 16 on a plastic substrate 10 having the organic buffer insulating film 11 in a desired pattern. (12) was applied (II), and then the photoresist film and the organic material thereon were removed using a lift-off method to form (III) in FIG. 4C, and then the organic semiconductor film 15 and the gate insulating film 13 thereon. ) Are sequentially laminated (IV), and the photosensitive film 16 is formed on the desired pattern thereon, and after exposure and development, an organic conductor 14 serving as a source / drain electrode is applied (V), and the photosensitive film and the organic material thereon The organic thin film transistor can be manufactured by removing the by using a lift-off method to form (VI) of FIG. 4C.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to Examples.

Example 1

First, the polyether sulfone (PES) substrate was heat-treated in a vacuum oven at 150 ° C. for 24 hours. On the heat treated PES substrate, an organic buffer, JSS362 (Sumitomo) was applied for 50 seconds at 2500 revolutions per minute with a spin coater. The applied JSS362 was cured by heat treatment at 150 ° C. for 30 minutes in an oven. Next, in order to form a pattern, an organic photosensitive agent, AZ5214 (Clariant) was deposited at 2,000 rpm using a spin coater to form a photosensitive film. The thickness of the photosensitive film at this time is 2.1 micrometers. Subsequently, after the first heat treatment at 115 ° C. for 90 seconds, the exposure time was 100 m seconds, the depth of field (DOF) was -0.9, and the I-line (wavelength 365 nm) was irradiated to sample 1, and the exposure time was Samples 1 were changed at intervals of 200 msec from 100 msec to 900 msec, and the depth of focus (DOF) was varied from 0.3 to -0.9 to 0.9 at sample 1 to make samples 2 to 35, respectively.

Subsequently, the photoresist was subjected to a blank exposure in a contact aligner for 35 seconds to reverse, developed in twice a developer (NMD3) for 75 seconds, and 140 ° C./90 on a hot plate. The heat treatment was performed for 2 seconds to cure the photoresist. When the secondary heat treatment is performed in an oven, the photosensitive agent may be cured at 120 ° C./30 minutes. PEDOT / PSS, an organic conductor, was applied on the cured photoresist at 120 rpm per minute for 120 seconds using a spin coater. The applied PEDOT was heat treated in an oven at 135 ° C. for 5 to 30 minutes. The resistance of the heat treated PEDOT was measured to be about 500 Ω / cm. Remove the photoresist film and the organic matter on it by lift-off method in which heat-treated PEDOT / PSS (Baytron) is immersed in methyl acetone for 5 to 20 hours, and then rinsed in deionized water for 5 minutes in an oven at 100 ° C. It was dried to obtain the desired fine pattern. The optical micrograph of the fine pattern thus obtained is shown in FIG. 5.

In order to evaluate the degree of implementation of the micro-pattern according to the exposure conditions, the sharpness of the photosensitive agent patterning was confirmed by arranging the optical micrographs of Samples 1 to 35 in the order of vertical exposure depth as the transverse exposure time. The photos thus arranged are shown in FIG. 6.

As shown in FIG. 6, the sharpness of the patterning became clear in the diagonal direction of Sample 1 in Sample 35. Sample 35 is less developed and the patterned surface is seen to be less clean. The degree of development of the pattern also appears to vary dramatically with exposure time rather than DOF. As the exposure time increases, the pattern becomes less clear because the photoresist is not completely removed in reaction with the PES substrate.

Example 2

The polyether sulfone (PES) substrate was heat treated at 150 ° C. for 24 hours in a vacuum oven. On the heat treated PES substrate, an organic buffer, JSS362 (Sumitomosa), was applied for 50 seconds at 2500 rpm using a spin coater. The applied JSS362 was cured by heat treatment at 150 ° C. for 30 minutes in an oven. In order to form a desired pattern, an organic photosensitive agent, PFi38a (Dongwoo Semiconductor Co., Ltd.) was deposited on a substrate at a revolution of 2,000 rpm using a spin coater to form a photoresist film. The thickness of the photosensitive film at this time is about 1.0 micrometer. After the first heat treatment of the photoresist film at 115 ° C. for 90 seconds, the exposure time was set to 270 m seconds, the depth of focus was 0.3, and the I-line (wavelength 365 nm) was irradiated to make Sample 1, and the exposure time was set to 270 m of Sample 1. Samples 2 to 28 were prepared by varying the interval from 50 seconds to 120 m seconds at an interval of 50 m seconds, and changing the depth of focus (DOF) from 0.3 to -1.5 of sample 1 at 0.3 intervals.

Subsequently, the photoresist was subjected to a blank exposure in a contact aligner for 35 seconds to reverse, developed in twice a developer (NMD3) for 75 seconds, and 140 ° C./90 on a hot plate. The heat treatment was performed for 2 seconds to cure the photoresist. PEDOT / PSS, an organic conductor, was coated on the cured photoresist at 120 rpm for 120 seconds using a spin coater. The coated PEDOT was heat treated in an oven at 135 ° C. for 5-30 minutes. The resistance of the heat treated PEDOT was measured to be about 500 Ω / cm. After removing the photoresist film and the organic matter on it by using a lift-off method in which the heat-treated PEDOT / PSS is immersed in methyl acetone for 5 to 20 hours, it is rinsed in deionized water and dried in an oven at 100 ° C. for 5 minutes to obtain a fine pattern. there was.

As in Example 1, in order to evaluate the degree of implementation of the fine pattern according to the exposure conditions, the sharpness of the photoresist patterning is arranged by sequentially arranging the optical microscope photographs of Samples 1 to 28 as the exposure time to the vertical depth of focus. Confirmed. The photos thus arranged are shown in FIG. 7. As shown in FIG. 7, it can be seen that the formation of the pattern has a large difference depending on the depth of focus, and the phenomenon that the photoresist film sticks to the PES substrate occurs depending on the exposure time. In terms of DOF, the change in developed shape was larger when the DOF was changed from -1.2 to -1.5 than when the DOF was changed from 0.3 to -1.2 days at an exposure time of 270 m seconds. If the DOF is 170m seconds, it can be seen that the DOF is developed in positive rather than negative. In the case of using PFi38a, the development was best performed at an exposure time of 270 msec and a DOF of -1.5.

The present invention has the following effects in the fine patterning method of the organic conductor.

First, it is possible to reduce the damage during patterning because it is possible to implement a fine pattern and at the same time does not affect the properties of organic matter.

Second, it is economical because the existing resource equipment can be used as it is.

Third, the flexible display and flexible electronics can be put to practical use in the future.

Claims (8)

(Iii) exposing and developing a photosensitive film on a flexible substrate; (Ii) applying the organic conductor by a wet process on the substrate on which the photoresist film is formed; And (Iii) removing the exposed and developed photoresist film and the organic material thereon using a lift-off method. The method of claim 1, wherein a polyether sulfone substrate, a polyimide substrate, or a polycarbonate substrate is used as the flexible substrate. The method of claim 1, wherein the exposing and developing step of the photosensitive film comprises: (a) a first heat treatment of the photosensitive film; (b) exposing the heat treated film to an I-line; (c) developing; (d) A method for fine patterning an organic photosensitizer comprising the step of secondary heat treatment. The fine patterning method of an organic conductor film according to claim 1, wherein in the exposing and developing step, exposure is performed under conditions of an exposure time of 100 msec to 600 msec and a depth of focus (DOF) of -0.6 to -1.5.  The method of claim 1, wherein PEDOT / PSS is used as the organic conductor.   The method of claim 1, wherein the lift-off method removes the photosensitive film and the organic material thereon by contacting the substrate coated with the organic conductor with methyl acetone.  An organic conductor film finely patterned by the method according to any one of claims 1 to 6.  An organic thin film transistor to which the fine patterned organic conductor film according to claim 7 is applied.

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