KR20070071178A - Manufacturing for organic thin film transistor - Google Patents

Abstract

A method for manufacturing an organic thin film transistor is provided to improve an electric characteristic of an organic semiconductor layer by increasing grain size of the organic semiconductor layer to be defined as a channel area and reducing a grain boundary acting as a charge trap site. A gate electrode(112) is formed on a substrate(110). A gate insulating layer(114) is formed on a front of the substrate including the gate electrode. A plasma treatment process is performed to the gate insulating layer for forming a hydrophilic first adhesive layer(114a). A mold is contacted with a predetermined area of the first adhesive layer for forming a hydrophobic second adhesive layer(114b). Source and drain electrodes(116a,116b) are formed on the first adhesive layer. An organic semiconductor layer(120) is formed on the gate insulating layer including the source and drain electrodes, and the second adhesive layer.

Description

Manufacturing Method of Organic Thin Film Transistor

1 is a cross-sectional view showing a schematic configuration of a conventional organic thin film transistor.

2A and 2B are photographs showing a crystal structure of a conventional organic semiconductor layer.

3A to 3D are cross-sectional views illustrating a method of manufacturing an organic thin film transistor according to a first embodiment of the present invention.

4 is a cross-sectional view of a liquid crystal display using an organic thin film transistor according to a first embodiment of the present invention.

5A through 5D are cross-sectional views illustrating a method of manufacturing an organic thin film transistor according to a second exemplary embodiment of the present invention.

6 is a cross-sectional view of a liquid crystal display using an organic thin film transistor according to a second embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

110, 210: substrate 112, 220: gate electrode

114, 218: gate insulating film 120, 216: organic semiconductor layer

116a, 116b, 214a, and 214b: source / drain electrodes 212: buffer film

114a, 114b, 212a, 212b: adhesive layer

The present invention relates to a thin film transistor, and more particularly to a method for manufacturing an organic thin film transistor.

In general, a thin film transistor is used as a switch element in an image display display. Among the thin film transistors, an organic thin film transistor uses a semiconductor organic material as a semiconductor layer material, and uses a flexible substrate instead of a glass substrate. Except for the silicon thin film transistor has a structurally similar form.

As shown in FIG. 1, the organic thin film transistor includes a gate electrode 52a formed using a metal on the lower substrate 51 and a gate formed on the lower substrate 51 including the gate electrode 52a. The insulating film 53, the source electrode 55a and the drain electrode 55b formed on the gate insulating film 53 at both edges of the gate electrode 52a, and the source / drain electrodes 55a and 55b, respectively. It consists of the organic-semiconductor layer 54 formed on the gate insulating film 53 containing.

The source / drain electrodes 55a and 55b are formed using metal inorganic materials such as palladium (Pd), gold (Au), and silver (Ag).

On the other hand, in the organic thin film transistor as described above, the gate insulating film 53 may be formed of an organic material. The gate insulating film 53 formed of an organic material and the source / drain electrodes 55a and 55b formed of an inorganic material, that is, a metal may be used. Plasma surface treatment is involved in the gate insulating film to improve the adhesion between them.

However, the plasma-treated gate insulating film is hydrophilic, and when the organic semiconductor layer is formed on the hydrophilic gate insulating film, the gate insulating film is grown to an organic semiconductor layer having a small grain.

As shown in FIG. 2A, the grain structure of the organic semiconductor layer formed on the hydrophobic gate insulating film without being plasma treated, and the organic semiconductor layer formed on the hydrophilic gate insulating film as shown in FIG. 2B, are plasma treated. Comparing the grain structure, it can be seen that the organic semiconductor formed on the plasma insulating gate insulating film has a small grain structure.

Therefore, when the organic semiconductor layer is formed on the hydrophilic gate insulating film, the grain size decreases, and the grain boundary acting as a charge trap site increases, thereby increasing the electrical characteristics of the organic semiconductor layer. The problem of deterioration occurs.

The present invention is to provide a method for manufacturing an organic thin film transistor to improve the electrical properties of the organic semiconductor layer.

A method of manufacturing the organic thin film transistor of the present invention for achieving the above object comprises the steps of forming a gate electrode on a substrate, forming a gate insulating film on the entire surface of the substrate including the gate electrode, plasma on the gate insulating film Performing a treatment step to form a hydrophilic first adhesive layer, contacting a mold with a predetermined region of the first adhesive layer to form a hydrophobic second adhesive layer, and source / drain on the first adhesive layer Forming an electrode, and forming an organic semiconductor layer on the gate insulating layer including the source / drain electrode and the second adhesive layer.

The mold is formed of a thermosetting material including poly dimethyl siloxane (PDMS).

Plasma treatment process for forming the first adhesive layer is O ₂ , H ₂ , He, H ₂ , SF ₆ And any one of CF ₄ or a gas mixed therebetween.

The gate insulating layer is formed of an organic insulating material, and the organic semiconductor layer is formed of any one of a liquid crystal line polyfluorene block copolymer (LCPBC), pentacene, and polythiophene, and the source / drain electrode is made of metal. It is formed of inorganic material.

The method of manufacturing the organic thin film transistor of the present invention for achieving the above object comprises the steps of forming a buffer film on a substrate, performing a plasma treatment process on the buffer film, to form a hydrophilic first adhesive layer, Contacting a mold with a predetermined region of the first adhesive layer to form a hydrophobic second adhesive layer, forming a source / drain electrode on the first adhesive layer, and the source / drain electrode and the second adhesive layer Forming an organic semiconductor layer on the formed buffer film, and forming a gate insulating film and a gate electrode on the organic semiconductor layer, respectively.

Plasma treatment process for forming the first adhesive layer is O ₂ , H ₂ , He, H ₂ , SF ₆ And any one of CF ₄ or a gas mixed therebetween.

The mold is formed of a thermosetting material including poly dimethyl siloxane (PDMS).

The buffer layer is formed of an organic insulating material, and the organic semiconductor layer is formed of any one of liquid crystalline polyfluorene block copolymer (LCPBC), pentacene, and polythiophene, and the source / drain electrode is a metal inorganic Form into material.

Embodiments of the method for manufacturing the organic thin film transistor according to the present invention having the above characteristics will be described in more detail with reference to the accompanying drawings.

3A to 3D are cross-sectional views illustrating a method of manufacturing an organic thin film transistor according to a first embodiment of the present invention, and FIG. 4 is a cross-sectional view of a liquid crystal display using an organic thin film transistor according to a first embodiment of the present invention. to be.

First, the organic thin film transistor according to the first embodiment of the present invention, as shown in Figure 3d, a substrate including a gate electrode 112 formed of a metal material on the substrate 110, and the gate electrode 112 (110) a gate insulating film 114 formed of an organic material on the front surface, a source electrode 116a and a drain electrode 116b formed of a metal material on the gate insulating film 114 at both edges of the gate electrode 112, An organic semiconductor layer 120 such as a liquid crystalline polyfluorene block copolymer (LCPBC), pentacene, polythiophene, and the like formed on the gate insulating layer 114 including the source / drain electrodes 116a and 116b. And a hydrophilic adhesive layer 114a formed in a region where the source / drain electrodes 116a and 116b are in contact with the gate insulating layer 114, and a region in which the organic semiconductor layer 120 is in contact with the gate insulating layer 114. Composed of a hydrophobic adhesive layer 114b .

On the other hand, the hydrophilic adhesive layer 114a is formed only in a region where the source / drain electrodes 116a and 116b are in contact with the gate insulating layer 114 to improve the adhesive force between these films and to form a hydrophobic adhesive layer. The organic semiconductor layer 120 is formed on the gate insulating film 114 on which the 114b is formed, so that the grain size of the organic semiconductor layer is increased, and grain boundaries acting as charge trap sites are formed. It is reduced to improve the electrical properties of the organic semiconductor layer.

The manufacturing method of the organic thin film transistor as described above is as follows.

First, as illustrated in FIG. 3A, a metal is deposited on a substrate 110 of glass or transparent plastic, and then patterned by photo etching to form a gate electrode 112.

The gate electrode is made of at least one or more of low resistance metal materials such as chromium (Cr), copper (Cu), molybdenum (Mo), aluminum (Al), aluminum alloy (Al alloy), tungsten (W) series. .

Thereafter, an organic insulating material is coated on the entire surface including the gate electrode 112 to form a gate insulating layer 114.

The gate insulating layer 114 forms an organic insulating material such as benzocyclobutene (BCB), an acrylic material, and a polyimide.

Subsequently, a plasma treatment process is performed on the gate insulating layer 114 to form a hydrophilic adhesive layer 114a on the surface of the gate insulating layer 114.

The plasma treatment is O ₂ , H ₂ , He, H ₂ , SF ₆ And a gas of any one of CF ₄ or a gas mixed therebetween.

Next, as shown in FIG. 3B, the mold 115 is contacted with a predetermined region on the hydrophilic adhesive film 114a to change the region in which the mold 115 is in contact with the hydrophobic adhesive film 114b.

Here, the mold 115 is manufactured by a separate process as a thermosetting material containing poly dimethyl siloxane (Poly-dimethyl Siloxane: hereinafter referred to as "PDMS").

Specifically, when the mold 115 including the PDMS is pressed on the hydrophilic adhesive film 114a, the region in contact with the mold 115 is separated from the -OH group of the terminal group on the surface thereof, thereby changing to a hydrophobic region. To the adhesive film 114b.

Accordingly, in the adhesive film, the hydrophobic adhesive film 114b and the hydrophilic adhesive film 114a coexist.

As shown in FIG. 3C, the mold 115 is removed, and a metal layer is formed on the gate insulating layer 114 on which the hydrophobic adhesive layer 114b and the hydrophilic adhesive layer 114a are formed. Subsequently, a photo resist (not shown) is coated on the metal layer, the photo mask having a predetermined pattern formed on the photo resist is aligned, exposed by irradiation with light, and then developed after that. Pattern. Subsequently, the metal layer is selectively etched using the patterned photoresist as a mask to form source / drain electrodes 116a and 116b on the hydrophilic adhesive film 114a.

The source / drain electrodes 116a and 116b are made of at least one or more of low resistance metal inorganic materials such as chromium (Cr), molybdenum (Mo), aluminum (Al), and aluminum alloy (Al alloy).

Meanwhile, the hydrophilic adhesive film 114a formed by the plasma treatment process increases the adhesion between the source / drain electrodes 116a and 116b and the gate insulating film 114 of the organic material.

Subsequently, as illustrated in FIG. 3D, an organic material is coated on the entire surface of the gate insulating layer 114 on which the source / drain electrodes 116a and 116b and the hydrophobic adhesive film 114b are formed, and then patterned to form an organic semiconductor layer. The organic thin film transistor is completed by forming 120.

Organic materials to be used as the organic semiconductor layer include liquid crystal line polyfluorene block copolymer (LCPBC), pentacene (Pentacene), polythiophene (polythiophene).

At this time, the organic semiconductor layer 120 is formed on the gate insulating film 114 on which the hydrophobic adhesive film 114b formed due to the contact of the mold 115 forms a grain size of the organic semiconductor layer to be defined as a channel region. Is increased and the grain boundary acting as the charge trap site is reduced to improve the electrical characteristics of the organic semiconductor layer.

On the other hand, the liquid crystal display device including the organic thin film transistor according to the first embodiment as described above, BCB, acrylic material, polyimide on the substrate 110, the organic thin film transistor is formed as shown in FIG. Indium Tin Oxide (ITO) or Indium Zinc (IZO) in the pixel region of the passivation layer 122 to be connected to the drain electrode 116b through the contact hole 119 and the passivation layer 122 formed of an organic insulating material such as A pixel electrode 124 formed of Oxie is further provided. In addition, the upper substrate 132 opposite to the lower substrate 110 has a black matrix 130 that shields light from portions other than the pixel region, a color filter layer 128 for implementing color, and a pixel for driving the pixels. The common electrode 126 is provided. The upper substrate 132 and the lower substrate 110 are bonded to each other with a predetermined space, and the liquid crystal layer 131 is formed therebetween.

On the other hand, the organic light emitting diode device (not shown) formed with the organic thin film transistor according to the first embodiment as described above, the first substrate and the upper substrate facing the substrate 110 on which the organic thin film transistor is formed; An organic light emitting diode having a second electrode and an organic light emitting layer therebetween is formed.

Meanwhile, as described above, the first embodiment of the present invention has described a bottom gate structure of the structure of the organic thin film transistor, and the second embodiment of the present invention is a top-gate of the structure of the organic thin film transistor. The top gate structure will be explained.

5A through 5D are cross-sectional views illustrating a method of manufacturing an organic thin film transistor according to a second embodiment of the present invention, and FIG. 6 is a cross-sectional view of an LCD device using an organic thin film transistor according to a second embodiment of the present invention. It is a cross section.

First, the organic thin film transistor according to the second embodiment of the present invention, as shown in Figure 5d, the buffer film 212 formed of an organic material on the substrate 210 and the buffer film 212, respectively Source / drain electrodes 214a and 214b formed of an island-shaped metal layer, liquid crystalline polyfluorene block copolymer (LCPBC) and pentacene formed on the source / drain electrodes 214a and 214b and the buffer layer 212. , An organic semiconductor layer 216 such as polythiophene, a gate insulating film 218 formed on the organic semiconductor layer 216, and the gate insulating film overlapping the source / drain electrodes 214a and 214b. The gate electrode 220 formed on the 218, the hydrophilic adhesive layer 212a formed in the region where the source / drain electrodes 214a and 214b and the buffer film 212 contact, and the organic semiconductor layer 216. And a hydrophobic adhesive layer 212b formed in a region where the buffer film 212 is in contact with each other.

On the other hand, the hydrophilic adhesive layer 212a is formed only in a region where the source / drain electrodes 214a and 214b are in contact with the buffer film 212, thereby improving adhesion between these films and forming a hydrophobic adhesive layer 212b. An organic semiconductor layer 216 is formed on the film 212 to increase the grain size of the organic semiconductor layer and to reduce grain boundaries serving as charge trap sites, thereby improving the electrical characteristics of the organic semiconductor layer.

The manufacturing method of the organic thin film transistor as described above is as follows.

First, as shown in FIG. 5A, a buffer film 212 is formed on a substrate 210 of glass or transparent plastic.

The buffer film 212 is deposited to improve crystal growth of an organic semiconductor layer to be formed later, and forms an organic insulating material such as benzocyclobutene (BCB), an acrylic material, and a polyimide.

Subsequently, a plasma treatment process is performed on the buffer film 212 to form a hydrophilic adhesive film 212a on the surface of the buffer film 212.

The plasma treatment is O ₂ , H ₂ , He, H ₂ , SF ₆ And a gas of any one of CF ₄ or a gas mixed therebetween.

Subsequently, as shown in FIG. 5B, the mold 213 is contacted with a predetermined region on the hydrophilic adhesive film 212a to convert the region in which the mold 213 is in contact with the hydrophobic adhesive film 212b.

Here, the mold 213 is manufactured by a separate process as a thermosetting material including poly dimethyl siloxane (hereinafter referred to as "PDMS").

Specifically, when the mold 213 containing the PDMS is pressed onto the hydrophilic adhesive film 212a, the region in contact with the mold 213 is separated from the -OH group of the terminal group on the surface thereof, thereby changing to a hydrophobic region. To the adhesive film 212b.

Accordingly, in the adhesive film, the hydrophobic adhesive film 212b and the hydrophilic adhesive film 212a coexist.

As shown in FIG. 5C, the mold 213 is removed, and a metal layer is formed on the buffer film 212 on which the hydrophilic adhesive film 212a and the hydrophobic adhesive film 212b are formed. Applying a photoresist (not shown) on the photoresist, aligning the photomask having a predetermined pattern formed on top of the photoresist, and then irradiated with light to expose and then develop the patterned photoresist (not shown) )do. Subsequently, the metal layer is selectively etched using the patterned photoresist as a mask to form source / drain electrodes 214a and 214b on the adhesive layer 212a. The patterned photoresist (not shown) is removed.

The source / drain electrodes are made of at least one or more of low resistance metal inorganic materials such as chromium (Cr), molybdenum (Mo), aluminum (Al), and aluminum alloy (Al alloy).

On the other hand, the hydrophilic adhesive film 212a formed by the plasma treatment process increases the adhesion between the source / drain electrodes 214a and 214b and the buffer film 212 of the organic material.

Subsequently, as shown in FIG. 5D, an organic material is coated on the entire surface of the buffer film 212 on which the source / drain electrodes 214a and 214b and the hydrophobic adhesive film 212b are formed, and then patterned to form an organic semiconductor layer ( 216).

Organic materials to be used as the organic semiconductor layer include liquid crystal line polyfluorene block copolymer (LCPBC), pentacene (Pentacene), polythiophene (polythiophene).

In this case, the organic semiconductor layer 216 is formed on the hydrophobic adhesive film 212b formed due to the contact of the mold 213, thereby increasing the grain size of the organic semiconductor layer to be defined as a channel region, and thereby causing charge trap sites. The grain boundary acting as a reducing layer is reduced to improve the electrical characteristics of the organic semiconductor layer.

Subsequently, an inorganic insulating material is deposited on the organic semiconductor layer 216 or an organic insulating material is applied to form the gate insulating film 218.

The gate insulating layer 218 forms an inorganic insulating material such as silicon oxide (SiOx) or silicon nitride (SiNx), or forms an organic insulating material such as benzocyclobutene (BCB), acrylic material, or polyimide. However, it may be preferable to form the gate insulating film using the organic insulating material rather than the inorganic insulating material for the contact property with the organic semiconductor layer to be formed later.

After depositing a metal on the gate insulating layer 218 and patterning it by photo etching, the gate electrode 220 is formed to overlap the source / drain electrodes 214a and 214b, thereby completing an organic thin film transistor.

The gate electrode is made of at least one or one or more of metal materials such as chromium (Cr), copper (Cu), molybdenum (Mo), aluminum (Al), aluminum alloy (Al alloy), tungsten (W) series.

On the other hand, the liquid crystal display device including the organic thin film transistor according to the second embodiment, as shown in Figure 6, on the substrate 210, the organic thin film transistor is formed, such as BCB, acrylic material, polyimide Indium Tin Oxide (ITO) or Indium Zinc Oxie (IZO) in the pixel region of the passivation layer 222 so as to be connected to the drain electrode 214b through the contact hole 219 and the passivation layer 222 formed of an insulating material. The pixel electrode 224 is further provided. In addition, the upper substrate 232 opposite to the lower substrate 210 may include a black matrix 230 that shields light from portions other than the pixel region, a color filter layer 228 for implementing color, and a pixel for driving the pixels. The common electrode 226 is provided. The upper substrate 232 and the lower substrate 210 are bonded to each other with a predetermined space, and the liquid crystal layer 231 is formed therebetween.

On the other hand, the organic light emitting diode device (not shown) formed with the organic thin film transistor according to the second embodiment as described above, the first substrate and the upper substrate facing the substrate 210 on which the organic thin film transistor is formed; An organic light emitting diode having a second electrode and an organic light emitting layer therebetween is formed.

According to the organic thin film transistor and the manufacturing method thereof according to the present invention, by forming the organic semiconductor layer on the insulating film of the organic material converted to hydrophobic (hydrophobic), the grain size of the organic semiconductor layer to be defined as a channel region is increased, The grain boundary acting as a trap trap site is reduced, thereby improving the electrical characteristics of the organic semiconductor layer.

In addition, according to the organic thin film transistor according to the present invention and a method for manufacturing the same, the hydrophilic adhesive film formed by the plasma treatment step is due to the hydrophilic adhesive film formed between the source / drain electrode and the buffer film of the organic material, There is an effect to increase the adhesion of.

Claims (12)

Forming a gate electrode on the substrate, Forming a gate insulating film on an entire surface of the substrate including the gate electrode; Performing a plasma treatment process on the gate insulating film to form a hydrophilic first adhesive layer; Contacting a mold with a predetermined region of the first adhesive layer to form a hydrophobic second adhesive layer; Forming a source / drain electrode on the first adhesive layer; And forming an organic semiconductor layer on the gate insulating film including the source / drain electrode and the second adhesive layer. The plasma treatment process of claim 1, wherein the plasma treatment process of forming the first adhesive layer is performed. O ₂ , H ₂ , He, H ₂ , SF ₆ And CF _{4 using} any one of the gases or a mixed gas therebetween. The method of claim 1, wherein the mold A method of manufacturing an organic thin film transistor, characterized in that formed of a thermosetting material containing poly dimethyl siloxane (PDMS). The method of claim 1, wherein the gate insulating film Method for manufacturing an organic thin film transistor, characterized in that formed with an organic insulating material. The method of claim 1, wherein the organic semiconductor layer LCPBC (Liquid Crystalline Polyfluorene Block copolymer), pentacene (Pentacene) and polythiophene (polythiophene) of any one of the manufacturing method of an organic thin film transistor. The method of claim 1, wherein the source / drain electrode A method of manufacturing an organic thin film transistor, characterized in that formed of a metal inorganic material. Forming a buffer film on the substrate, Performing a plasma treatment process on the buffer film to form a hydrophilic first adhesive layer; Contacting a mold with a predetermined region of the first adhesive layer to form a hydrophobic second adhesive layer; Forming a source / drain electrode on the first adhesive layer; Forming an organic semiconductor layer on the buffer layer on which the source / drain electrodes and the second adhesive layer are formed; And forming a gate insulating film and a gate electrode on the organic semiconductor layer, respectively. The method of claim 7, wherein the plasma treatment process for forming the first adhesive layer Method of manufacturing an organic thin film transistor, characterized in that performed using any one of O ₂ , H ₂ , He, H ₂ , SF ₆ and CF ₄ gas or a mixed gas therebetween. The method of claim 7, wherein the mold A method of manufacturing an organic thin film transistor, characterized in that formed of a thermosetting material containing poly dimethyl siloxane (PDMS). The method of claim 7, wherein the buffer film Method for manufacturing an organic thin film transistor, characterized in that formed with an organic insulating material. The method of claim 7, wherein the organic semiconductor layer A method of manufacturing an organic thin film transistor, characterized in that formed of any one of the liquid crystal line polyfluorene block copolymer (LCPBC), pentacene (Pentacene) and polythiophene (polythiophene). The method of claim 7, wherein the source / drain electrodes A method of manufacturing an organic thin film transistor, characterized in that formed of a metal inorganic material.

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