KR20120064533A - Electrophoretic display device and method of fabrication thereof - Google Patents

Abstract

PURPOSE: An electrophoresis display device and a manufacturing method thereof are provided to reduce manufacturing costs and simplify manufacturing processes by directly forming an electrophoresis layer on a substrate. CONSTITUTION: A partition wall(180) is formed on a buffer layer(182). The partition wall is formed on the buffer layer which is arranged in a matrix form on a first substrate. An electrophoresis material is filled inside the partition wall. The electrophoresis material includes particles having positive and negative electric charge properties. A protective layer is formed on the first substrate.

Description

Electrophoretic display device and its manufacturing method {ELECTROPHORETIC DISPLAY DEVICE AND METHOD OF FABRICATION THEREOF}

The present invention relates to an electrophoretic display device and a method of manufacturing the same.

In general, an electrophoretic display device is an image display device using a phenomenon in which colloidal particles move to either polarity when a pair of electrodes to which voltage is applied is immersed in a colloidal solution, and has a wide viewing angle, high reflectance, and low consumption without using a backlight. Since it has characteristics, such as an electric power, it is attracting attention as an electronic device, such as an electric paper.

The electrophoretic display device has a structure in which an electrophoretic layer is interposed between two substrates, one of the two substrates is made of a transparent substrate, and the other is composed of an array substrate on which a driving element is formed, thereby reflecting input light. The image can be displayed in the reflective mode.

1 is a view showing the structure of a conventional electrophoretic display device (1).

As shown in FIG. 1, the electrophoretic display device 1 includes a first substrate 20 and a second substrate 40 including a plurality of pixel regions, and an image display portion of the first substrate 20. A partition wall formed between the pixel electrode 18, the common electrode 42 formed on the second substrate 40, and an image non-display portion between the pixel and the pixel area of the second substrate 40 to partition each pixel. 80 and an electrophoretic layer 60 formed between the first substrate 20 and the second substrate 40.

Although not shown in the drawing, a thin film transistor is formed in each pixel region, and an electric field is formed between the pixel electrode 18 and the common electrode 42 as a voltage is applied to the pixel electrode 18. The second substrate 40 including the 60 is bonded to the first substrate 20 by an adhesive layer. The electrophoretic layer 60 is composed of an electrophoretic material in which white particles 64 and black particles 65 having positive and negative charge characteristics, respectively, are dispersed in a dispersion medium 62.

In the electrophoretic display device having such a structure, since the white particles 164 have positive charge characteristics, when the positive voltage is applied to the pixel electrode 18 from the outside, the common electrode 42 has a relatively negative potential. Therefore, the white particles 64 having a positive charge move toward the common electrode 42. Therefore, when light is input from the outside, that is, the upper portion of the second substrate 40, the input light is mostly reflected by the white particles 64, so that white is implemented in the electrophoretic display device.

On the contrary, when a negative voltage is applied to the pixel electrode 18, the common electrode 42 has a (+) potential, and the white particles 64 having a (+) charge are transferred to the first substrate 20. When the light is input from the outside, the input light is hardly reflected, thereby realizing black.

A manufacturing method of the conventional electrophoretic display device 1 having the above structure is schematically described as follows.

2 is a flowchart schematically showing a method of manufacturing a conventional electrophoretic display device 1.

As shown in FIG. 2, first, a plurality of gate lines and data lines defining pixel regions are formed on a first substrate 20, and the gate lines and data are formed in each of the pixel regions. A thin film transistor which is a driving element connected to the line is formed (S101). Subsequently, the pixel electrode 18 is formed on the first substrate 20 on which the thin film transistor is formed (S102).

Meanwhile, the common electrode 42 is formed on the second substrate 40 (S103). Subsequently, a partition wall is formed on the second substrate 40 to partition each pixel area, and then an electrophoretic material is filled in the pixel area partitioned by the partition wall to form an electrophoretic layer 60 (S105). . Thereafter, the common electrode 42 is formed on the second substrate 40 on which the electrophoretic layer 60 is formed, and a protective film is attached thereon (S105 and S106). At this time, although not shown in the figure, an adhesive layer is formed on the common electrode 42 so that the protective film is attached to the adhesive layer. In order to prevent the adhesion of the adhesive layer from deteriorating or the adhesion of the foreign matter to the adhesive layer when the second substrate 40 is transferred to the bonding process in order to bond the second substrate 40 to the first substrate 20. To be attached.

Typically, an electrophoretic display device manufacturer receives a second substrate 40 on which an electrophoretic layer 60 is formed, and attaches the second substrate 40 to the first substrate 20. That is, the second substrate 40 having the electrophoretic layer 60 formed thereon is transferred from the outside to the electrophoretic display element forming line, and then the first substrate 20 and the second substrate 40 are bonded to each other to form the electrophoretic display element. To complete.

Therefore, since the second substrate 40 on which the electrophoretic layer 60 is formed has to be transported a long distance by a conveying means such as a vehicle, the adhesive force of the adhesive layer decreases during the conveying process, so that the first substrate 20 and the second substrate ( When bonding the 40) may cause a defect, the protective film is to prevent the defect by preventing the adhesive force of the adhesive layer is weakened.

The second substrate 40 transferred to the manufacturing line of the electrophoretic display device manufacturer is peeled off the protective film is attached, and then aligned with the first substrate 20 to be bonded to complete the electrophoretic display device (S109).

However, the following problem occurs in the conventional electrophoretic display device 1 manufactured by the above method.

In the conventional electrophoretic display device 1, the first substrate 20 and the second substrate 40 are separately manufactured, and then the first and second substrates 20 and 40 are bonded to each other by an adhesive layer. .

However, since the unit pixels of the electrophoretic display element are formed to have a small size of less than 150 μm in width and length, it is very difficult to align the electrophoretic layer with the pixels so as to exactly fit this size. If the first substrate on which the electrophoretic layer and the thin film transistor are formed is not aligned correctly, the electric field may not be correctly transferred to the electrophoretic particles, which may cause a driving error.

In addition, since the first substrate 20 and the second substrate 40 are each manufactured in different processes, they are transported by a conveying means and then bonded to each other in the bonding process, so that the manufacturing process cannot be formed inline. The manufacturing process is delayed and the manufacturing cost increases.

Meanwhile, the common electrode 42 is formed on the second substrate 40, the electrophoretic layer 60 is applied, and an adhesive layer is applied. Then, the second substrate 40 is transferred to a bonding process to transfer the first substrate 20. ) In order to prevent the adhesion of the adhesive layer from deteriorating or adhered to the adhesive layer, the adhesive film must be transported with the protective film attached to the adhesive layer, and the second substrate 40 transferred at the same time is transferred to the first substrate. In order to attach to the 20, the protective film must be peeled from the second substrate 40. Static electricity is generated during the peeling of the protective film, and the generated static electricity causes misalignment in the initial arrangement of the electrophoretic particles. During operation of the electrophoretic display element, a moire in the shape of a comb-pattern was caused.

As described above, in the conventional electrophoretic display device, since the first substrate 20 and the second substrate 40 are manufactured in different processes, the first substrate 20 and the second substrate 40 when the electrophoretic layer is bonded. There is a problem that misalignment occurs or the process becomes complicated, and static electricity is generated when the adhesive layer is peeled off, resulting in poor image quality.

The present invention is to solve the above problems, to provide an electrophoretic display device and a method for manufacturing the electrophoretic layer that can reduce the manufacturing cost and simplify the manufacturing process by directly forming the electrophoretic layer on the substrate on which the thin film transistor is formed The purpose.

Another object of the present invention is to provide an electrophoretic display device and a method of manufacturing the reverse taper formed in the partition wall or to prevent the undercut to occur in the partition wall.

In order to achieve the above object, an electrophoretic display device manufacturing method according to an embodiment of the present invention comprises the steps of providing a first substrate and a second substrate comprising an image display unit and a non-display unit including a plurality of pixels; Forming a thin film transistor on the first substrate; Forming a protective layer on the first substrate on which the thin film transistor is formed; Forming a pixel electrode on the image display unit on the protective layer; Forming a buffer layer on the non-image display unit on the protective layer; Forming a partition on the buffer layer; Forming an electrophoretic layer by filling an electrophoretic material in a pixel inside the barrier rib above the protective layer; Forming a common electrode on the second substrate; And bonding the first substrate and the second substrate to each other.

The forming of the buffer layer may include depositing a photosensitive organic material on a protective layer; Baking the photosensitive organic material; And developing the photosensitive organic material, wherein the forming of the partition wall comprises: stacking the photosensitive organic material on a protective layer on which a buffer layer is formed; Baking the photosensitive organic material; And developing the photosensitive organic material.

The barrier rib and the buffer layer are made of the same material, and the buffer layer is formed to a thickness of 0.05-20 μm, preferably 0.05-10 μm, more preferably 0.05-3 μm.

In addition, an electrophoretic display device manufacturing method according to another embodiment of the present invention comprises the steps of providing a first substrate and a second substrate including an image display unit and a non-image display unit including a plurality of pixels; Forming a thin film transistor on the first substrate; Forming a protective layer on the first substrate on which the thin film transistor is formed; Forming a pixel electrode on the image display unit on the protective layer; Forming an insulating layer including an insulating material and an additive having a glass transition temperature lower than a baking temperature of the insulating material on the protective layer; Baking the insulating layer; Developing a baked insulating layer to form a partition on the image non-display portion on the protective layer; Forming an electrophoretic layer by filling an electrophoretic material in a pixel inside the barrier rib above the protective layer; Forming a common electrode on the second substrate; And bonding the first substrate and the second substrate to each other.

An additive flows under the insulating layer by baking the insulating layer, wherein the insulating material includes a photosensitive resin and the additive includes a polymer organic material.

An electrophoretic display device according to an embodiment of the present invention includes a first substrate and a second substrate including an image display unit and a non-image display unit including a plurality of pixels: a thin film transistor formed on the first substrate; A protective layer on the substrate on which the thin film transistor is formed; A pixel electrode formed on the image display unit on the protective layer; A buffer layer formed on an image non-display portion of the protective layer; Barrier ribs formed on the buffer layer; An electrophoretic layer formed inside the partition wall in the unit pixel; And a common electrode formed on the second substrate.

In addition, an electrophoretic display device according to another exemplary embodiment of the present invention may include a first substrate and a second substrate including an image display unit and a non-image display unit including a plurality of pixels: a thin film transistor formed on the first substrate; A protective layer on the substrate on which the thin film transistor is formed; A pixel electrode formed on the image display unit on the protective layer; Barrier ribs formed on the non-image display unit of the protective layer; An electrophoretic layer formed inside the partition wall in the unit pixel; And a common electrode formed on the second substrate, wherein the partition is made of an insulating material and an additive having a glass ion lower than a baking temperature of the insulating material.

In the present invention, since the electrophoretic layer is directly formed on the array substrate on which the thin film transistor is formed, the electrophoretic layer can be used to bond the electrophoretic layer to the array substrate. have. In addition, since the electrophoretic layer may be formed inline on the manufacturing line of the array substrate forming the thin film transistor, the manufacturing process may be simplified.

In addition, in the present invention, since the mask process is not necessary when forming the pixel electrode, the manufacturing process can be further simplified and the manufacturing cost can be greatly reduced.

In addition, in the present invention, it is possible to prevent the partition wall from reverse tapering or the occurrence of undercut in the lower region, thereby preventing the image quality from deteriorating.

1 is a view showing a conventional electrophoretic display device.
2 is a flow chart briefly showing a method of manufacturing a conventional electrophoretic display device.
3 is a flow chart briefly showing a method of manufacturing an electrophoretic display device according to a first embodiment of the present invention.
4A-4H schematically illustrate a manufacturing line of an electrophoretic display device according to an embodiment of the present invention.
5A and 5B illustrate a method of forming an electrophoretic layer of an electrophoretic display device according to an embodiment of the present invention, respectively.
6A and 6B are diagrams showing that reverse tapers are formed in partition walls and undercuts are formed in lower regions, respectively.
7A-7D schematically illustrate a manufacturing line of an electrophoretic display device according to another exemplary embodiment of the present invention.

Hereinafter, an electrophoretic display device and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a flowchart schematically illustrating a manufacturing process of an electrophoretic display device according to the present invention.

As shown in FIG. 3, first, a plurality of gate lines and data lines defining pixel regions are formed on a first substrate, and thin film transistors, which are driving elements connected to the gate lines and data lines, are formed in each of the pixel regions. (S101). Subsequently, a partition wall is formed in the image non-display portion on the first substrate on which the thin film transistor is formed, and then pixel electrodes are formed in the image display portion (S102 and S103).

In this case, the barrier rib and the pixel electrode are processed by the same photo process. In general, the formation of a metal pattern or patterning of an insulating layer in a manufacturing process of an electrophoretic display device is performed by photolithography using a photo-mask. In the present invention, the barrier rib and the pixel electrode are formed on the same photomask. It is formed on the same process. In addition, the pixel electrode may be formed without a separate photo process. That is, a photoresist layer laminated to etch the metal layer is patterned without using a photomask, and the pixel layer is formed by etching the metal layer by the patterned photoresist layer.

Subsequently, an electrophoretic material is applied to the pixel region partitioned by the partition wall of the first substrate, that is, the image display unit to form an electrophoretic layer (S204).

On the other hand, a common electrode is formed on the second substrate (S205), the second substrate on which the common electrode is formed is aligned with the first substrate, and then bonded to complete the electrophoretic display device (S206, S207).

The common electrode is formed by laminating a transparent conductive material on a second substrate by deposition or the like, and is formed by the same manufacturing line as a thin film transistor or a pixel electrode formed on the first substrate. In other words, in the present invention, since the process of the second substrate can be carried out in the same manufacturing line as the process of the first substrate, the first substrate and the first substrate and the first substrate are manufactured by manufacturing and transferring the second substrate in another factory in the conventional electrophoretic display device. Compared to the bonding of the two substrates, the first substrate and the second substrate can be manufactured inline, and the first substrate and the second substrate can be bonded together.

As described above, in the present invention, since the manufacturing process of the first substrate and the second substrate is performed inline, the adhesive layer or the adhesive layer for attaching the substrate on which the transfer of the second substrate or the electrophoretic layer is formed to the thin film transistor substrate is protected. To avoid the need for a protective film, the process of aligning the two substrates, the process of peeling off the protective film for protecting the adhesive layer of the substrate on which the electrophoretic layer is formed, etc., it is possible to simplify the manufacturing process.

Furthermore, in the present invention, since the partition wall and the pixel electrode can be formed by one photomask, the manufacturing process can be further simplified and the manufacturing cost can be greatly reduced.

Hereinafter, an actual manufacturing method of an electrophoretic display device according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 4A to 4H. In this case, although the electrophoretic display device is substantially composed of a plurality of unit pixels, only one pixel is shown in the drawing for convenience of description.

First, as shown in FIG. 4A, a Cr, Mo, Ta, Cu, Ti, Al, or Al alloy is formed on a first substrate 120 including an image display unit and an image non-display unit and made of a transparent material such as glass or plastic. After stacking an opaque metal having good conductivity by a sputtering process and etching by a photolithography process to form a gate electrode 111, the substrate 120 having the gate electrode 111 formed thereon. The gate insulating layer 122 is formed by stacking an inorganic insulating material such as SiO ₂ or SiNx by CVD (Chemicla Vapor Deposition).

Subsequently, as illustrated in FIG. 4B, a semiconductor material such as amorphous silicon (a-Si) is deposited on the entire first substrate 120 by CVD and then etched to form a semiconductor layer 113. In addition, although not shown in the drawing, an ohmic contact that ohmic-contacts the source electrode and the drain electrode to be subsequently formed with a semiconductor layer 113 by doping impurities or stacking amorphous silicon added with impurities to a part of the semiconductor layer 113. To form an ohmic contact layer. Subsequently, an electrically conductive opaque metal such as Cr, Mo, Ta, Cu, Ti, Al, or Al alloy is laminated on the first substrate 120 by sputtering, and then etched, and then etched on the semiconductor layer 113. In other words, the source electrode 115 and the drain electrode 116 are formed on the ohmic contact layer, and as shown in FIG. 4C, the entire first substrate 120 having the source electrode 115 and the drain electrode 116 formed thereon. A protective layer 124 is formed by stacking an organic insulating material such as BCB (Benzo Cyclo Butene) or photo acryl.

In addition, although not shown, the protective layer 124 may be formed of a plurality of layers. For example, the protective layer 124 may be formed of a double layer of an organic insulating layer made of an organic insulating material such as BCB or photoacryl and an inorganic insulating layer made of an inorganic insulating material such as SiO ₂ or SiNx, or inorganic It may be formed of an insulating layer, an organic insulating layer and an inorganic insulating layer. As the organic insulating layer is formed, the surface of the protective layer 124 is formed to be flat, and the interface characteristic with the protective layer 124 is improved by applying the inorganic insulating layer.

Subsequently, as shown in FIG. 4D, the protective layer 124 is etched to form a contact hole 117 through which the drain electrode 116 of the thin film transistor is exposed to the outside, and then an ITO is formed on the protective layer 124. A transparent conductive material such as (Indium Tin Oxide) or Indium Zinc Oxide (IZO), or a conductive metal such as Mo or AlNd, and the like, and are stacked and etched to form an image display on the image display unit through the contact hole 117 with the drain electrode 116. The pixel electrode 118 to be connected is formed.

Thereafter, as shown in FIG. 4E, the buffer layer 182 is formed on the non-display portion of the protective layer 124. The buffer layer 182 may be formed to a thickness of about 0.05-20 μm, preferably 0.05-10 μm, more preferably 0.05-3 μm. The buffer layer 182 is formed of a photosensitive organic insulating material such as a photosensitive resin. The buffer layer 182 is formed by applying and baking the photosensitive resin, followed by developing with a developer and baking again to cure. Since the buffer layer 182 is formed along a boundary region of pixels arranged in a matrix on the first substrate 120, the buffer layer 182 is also formed in a matrix on the first substrate 120.

Subsequently, as illustrated in FIG. 4F, the pixel electrode 118 stacks and develops a photosensitive organic material such as a photosensitive resin over the entire first substrate 120 on which the buffer layer 182 is formed, thereby forming a partition on the buffer layer 182. Form 180. Since the partition wall 180 is formed on the buffer layer 182 arranged in a matrix on the first substrate 120, the buffer layer 182 is also formed in a matrix on the first substrate 120.

The barrier 180 may be formed of a material different from that of the buffer layer 182. However, the partition wall 180 may be formed of the same material to reduce costs or simplify the process.

When the barrier 180 and the buffer layer 182 are formed of the same material, the surface of the buffer layer 182 may be treated to improve the wettability of the material for the buffer layer 182 and the barrier 180, thereby improving interface characteristics. . In this case, the surface treatment of the buffer layer 182 may include an oxygen plasma process, a hydrogen plasma process, and a SAM (Self Assembled Monlayer) coating.

When the barrier rib 180 and the buffer layer 182 are formed of different materials, it is preferable to use a material having a surface energy of about 5 mN / m ² or less for interfacial properties between the two layers.

Thereafter, as shown in FIG. 4G, the electrophoretic material is filled in the partition 180 to form the electrophoretic layer 160. The electrophoretic material is composed of particles having positive and negative charge characteristics. In this case, the particles may be white particles 164 and black particles 165, color particles such as cyan, magenta, yellow, or R (Red), G (Green), B It may be a color particle such as (Blue).

In the case of the white particles 164, particles having good reflectivity such as TiO ₂ are used, and in the case of the black particles 165, particles having black characteristics, such as carbon black, are used. In this case, the white particles 164 may have negative charge characteristics, the black particles 165 may have positive charge characteristics, the white particles 164 may have positive charge characteristics, and the black particles 165 may have negative charge characteristics.

In addition, in the case of color particles as a dye having a charge characteristic, the color particles may have a negative charge or may have a negative charge.

The electrophoretic material may include a dispersion medium such as a liquid polymer. The dispersion medium is a black particle, a white particle, and a color particle are distributed, and may be a liquid such as a liquid polymer or air itself. As described above, that the dispersion medium is air itself means that the particles move in the air as voltage is applied even without the dispersion medium.

When a liquid polymer is used as the dispersion medium, a black dispersion medium or a color dispersion medium may be used as the dispersion medium. When using a black dispersion medium absorbs light incident from the outside, it is possible to improve the contrast by displaying a clear black when implementing black. In addition, the color dispersion medium is used when the color is implemented by the electrophoretic material, each color pixel includes a dispersion medium of the corresponding color, it is possible to express a more vivid color when implementing the color.

In addition, the electrophoretic material may be a material in which a capsule filled with an electron ink is distributed in a polymer binder. At this time, the electron ink distributed in the capsule is composed of white particles (or white ink) and black particles (or black ink). In this case, the white particles and the black particles have positive and negative charge characteristics, respectively.

On the other hand, white particles, black particles, and color particles may be used not only a specific material but all currently known particles.

The filling of the electrophoretic material into the partition wall 180 may be performed by various methods, which will be described below.

5A and 5B illustrate a method of forming the electrophoretic layer 160 by filling an electrophoretic material into the partition wall 180 formed on the substrate 120.

The method illustrated in FIG. 5A relates to an inkjet method or a nozzle method. As shown in FIG. 5A, an electrophoretic material 160a is filled in a syringe (or nozzle) 185 and then the substrate 120 is filled. Position the syringe 185 on the top. Thereafter, the syringe 185 is moved on the substrate 120 while pressure is applied to the syringe 185 by an external air supply device (not shown) The electrophoretic material 160a is dropped to form an electrophoretic layer 160 on the substrate 120. [

The method illustrated in FIG. 5B relates to a squeeze method, and as shown in FIG. 5B, after the electrophoretic material 160a is coated on the substrate 120 on which the plurality of partition walls 180 are formed, the squeeze bar 187 is provided. By moving on the substrate 120 by the pressure of the squeeze bar 187 is filled with the electrophoretic material 160a into the partition 180 in the unit pixel to form the electrophoretic layer 160.

Of course, the present invention is not limited to the method as described above. The method described above shows an example of the process of forming the electrophoretic layer 160 that can be used in the present invention, and the present invention is not limited to this specific process. For example, various electrophoretic layer 160 forming processes such as casting printing, bar coating printing, screen printing, and mold printing may be applied to the present invention.

Subsequently, as shown in FIG. 4H, the sealing material is coated on the entire first substrate 120 as described above to form a sealing layer 168 to seal the electrophoretic layer 160, and then the first substrate 120. ) Is bonded to the second substrate 140 to complete the electrophoretic display device.

Although not shown in the drawings, a color filter layer may be formed on the second substrate 140. The color filter layer 146 is composed of R (Red), G (Green), B (Blue) color filters, and implements color when the electrophoretic material is composed of black particles and white particles.

The structure of the electrophoretic display device manufactured by the above method will be described in detail with reference to FIG. 4H.

As shown in FIG. 4H, the electrophoretic display device according to the present invention includes a gate electrode 111, a semiconductor layer 113, a source electrode 115, and a drain electrode 116 on an image non-display portion of the first substrate 120. A thin film transistor is formed and a protective layer 124 is formed thereon.

The pixel electrode 118 is formed on the image display part on the passivation layer 124, the buffer layer 182 is formed on the image ratio surface part, and the partition wall 180 is formed on the buffer layer 182. An electrophoretic layer 160 dl is disposed on the image display unit of the first substrate 120, that is, the pixel electrode 118 between the partition walls 180, so that the electrophoretic layer 160 directly contacts the pixel electrode 118. . Therefore, unlike the conventional electrophoretic display device, a separate adhesive layer for attaching the electrophoretic layer 160 between the electrophoretic layer 160, the pixel electrode 118, and the protective layer 124 is not required.

The electrophoretic layer 160 is sealed by an upper sealing layer 168, and the second substrate 140 on which the common electrode 142 is formed is bonded to the first substrate 120.

Meanwhile, in the present invention, the reason why the buffer layer 182 is formed below the partition wall 180 will be described in detail as follows.

The partition wall 180 is formed by applying and baking the photosensitive insulating layer, and then developing and baking the insulating layer baked by the developer. However, when the buffer layer 182 is not formed, the partition wall 180 is formed very thick with a thickness of about 10-100 μm. Therefore, when baking to etch the insulating layer, due to the thickness of the thick insulating layer, the insulating layer is not completely cured as a whole, but an uncured region is formed under the insulating layer. In addition, in order to develop the thick insulating layer as described above, the insulating layer is exposed to the developer for a long time, the development of the developer for a long time such that the lower region where the developer stays for a long time the etching degree is higher than the etching degree of the upper region.

As a result of the difference in etching speed between the uncured region and the hardened region and a long time phenomenon, as shown in FIG. 6A, the partition 180 is further developed toward the lower side, so that the lower region of the partition 180 is upper region. An inverse taper shape that becomes narrower in width is formed.

When such an inverse taper shape occurs in the partition wall 180, the pixel electrode 118 is not formed below the inverse taper region A, and thus, electrophoretic particles cannot be driven in this region. There is a problem that the reflectivity and contrast ratio by the electrophoretic particles are lowered.

In addition, when the thickness of the thick insulating layer does not completely harden the insulating layer as a whole, and an uncured region is formed in the lower portion of the insulating layer, the developing solution penetrates into the lower region when developing the insulating layer, FIG. 6B. As shown in FIG. 5, an under cut occurs in the lower region of the partition wall 180. The area B in which the undercut has occurred is also impossible to drive the electrophoretic particles, thereby reducing the reflectivity and contrast ratio by the electrophoretic particles.

In the present invention, the buffer layer 182 may be formed under the barrier 180 to solve the above problem. That is, since the insulating layer having a thickness much thinner than the partition wall 180 is laminated, baked, and developed to form the buffer layer 182, the entire insulating layer is completely cured from the top to the bottom during baking, which is caused by the uncured region during development. There is no difference in etching speed and a long thickness is not required due to the thin thickness, so that problems such as reverse taper or undercut do not occur in the buffer layer 182 itself.

In addition, even when the partition wall 180 is formed on the buffer layer 182, the thickness of the partition wall 180 is reduced by the thickness of the buffer layer 182, so that the insulating layer for forming the partition wall 180 is completely cured during baking. The difference in etching speed due to the uncured area does not occur, and a long time is not required due to the thin thickness, so that problems such as reverse taper or undercut do not occur in the partition wall 180.

As described above, in the present invention, the buffer layer 182 is formed under the partition wall 180, and the buffer layer 182 is formed by a development process different from that of the partition wall 180, thereby forming the partition wall 180 without the buffer layer 182. ), The thickness of the partition wall 180 can be reduced compared to the case where the protective layer 124 is directly formed on the protective layer 124, thereby preventing the partition wall 180 from being tapered or undercutting in the lower region.

Meanwhile, in the above description, the partition wall 180 and the buffer layer 182 are used in different terms. However, the partition wall 180 and the buffer layer 182 are formed at the same position to partition the pixels so as to partition the electrophoretic layer therein. Perform the same function to form 160. Therefore, a layer (that is, an upper and lower layers) in which the partition wall 180 and the buffer layer 182 are substantially combined serves as a substantial partition wall. Accordingly, the buffer layer 182 may be referred to as another partition wall.

Looking at the driving of the electrophoretic display device of such a structure is as follows. When the electrophoretic material 160 is formed of the white particles 164 and the black particles 165, since the white particles 164 have a positive charge or negative charge characteristics, a signal is input from the outside and formed on the first substrate 120. When a signal is applied to the pixel electrode 118 through the thin film transistor, the white particles 164 and the electrophoretic layer 160 are moved by an electric field generated between the pixel electrode 118 and the common electrode 142. .

For example, when the white particles 164 have a positive charge, when a positive voltage is applied to the pixel electrode 118, the common electrode 142 of the second substrate 140 has a relatively negative potential. Since the white particles 164 having a (+) charge is moved toward the second substrate 140. Therefore, when light is input from the outside, that is, the upper portion of the second substrate 140, the input light is mostly reflected by the white particles 164, so that white is implemented in the electrophoretic display device.

At this time, since the density of the white particles 164 moving toward the second substrate 140 or the distance from the second substrate 140 varies according to the intensity of the voltage applied to the pixel electrode 118 to be applied, Since the intensity of light input and reflected by the white particles 164 is also changed, it is possible to achieve a desired brightness.

On the contrary, when a negative voltage is applied to the pixel electrode 118, the common electrode 142 of the second substrate 140 has a (+) potential, so that the white particles 164 having a (+) charge are charged. When the light is input from the outside by moving to the first substrate 120, the input light is hardly reflected, thereby implementing black.

Meanwhile, when the white particles 164 have a negative charge, when a positive voltage is applied to the pixel electrode 118, the common electrode 142 of the second substrate 140 may have a relatively negative potential. Therefore, the white particles 164 having a negative charge are moved toward the first substrate 120. Therefore, when light is input from the outside, that is, the upper portion of the second substrate 140, since most of the input light is not reflected, black is implemented in the electrophoretic display device.

On the contrary, when a negative voltage is applied to the pixel electrode 118, the common electrode 142 of the second substrate 140 has a positive potential, so that the white particles 164 having a negative charge are charged. When the light is input from the outside by moving to the second substrate 140, the input light is reflected by the white particles 164, thereby implementing white.

When the electrophoretic material is formed of color particles, color particles such as R, G, B color particles, cyan, magenta, yellow, etc. may be formed according to a signal applied to the pixel electrode 118. The substrate 140 may be moved to implement a color mixed with the corresponding color or other pixels.

When the electrophoretic material is composed of a polymer filled with white particles and a capsule filled with black particles, since the white particles and the black particles included in the electron ink distributed in the capsule have positive and negative charge characteristics, signals from outside When a signal is applied to the pixel electrode 118, the white particles and the black particles are separated in the capsule by an electric field generated between the pixel electrode 118 and the common electrode 142. For example, when a negative voltage is applied to the pixel electrode 118, the common electrode 142 of the second substrate 140 has a relatively positive potential, so that white particles having a positive charge The black particles moving toward the first substrate 120 and having a (-) charge move toward the second substrate 140. In this state, when light is input from the outside, that is, the upper portion of the second substrate 140, the input light is reflected by the black particles, so that black is implemented in the electrophoretic display device.

On the contrary, when a positive voltage is applied to the pixel electrode 118, the common electrode 142 of the second substrate 140 has a negative potential, so that white particles having a positive charge are formed on the second substrate. Moving to 140, the black particles having a negative charge is moved to the first substrate 140.

In this state, when light is input from the outside, that is, the upper portion of the second substrate 140, the input light is reflected by the white particles, thereby implementing white.

In this case, when the white particles and the black particles in the capsule have negative charge and positive charge characteristics, respectively, white and black can be realized in the opposite operation.

7A to 7D are views illustrating a method of manufacturing an electrophoretic display device according to another exemplary embodiment of the present invention.

First, as shown in FIG. 7A, a gate electrode 211, a gate insulating layer 222, a semiconductor layer 213, a source electrode 215, and a drain electrode 216 are formed on the first substrate 220. A thin film transistor is formed, and a protective layer 224 is formed on the drain electrode 216 of the thin film transistor to be exposed to the outside through the contact hole 217. Subsequently, a pixel electrode 218 is formed to be electrically connected to the drain electrode 216 through the contact hole 217 on the image display portion on the protective layer 224.

Thereafter, as shown in FIG. 7B, the partition wall 280 is formed in the image non-display portion on the protective layer 224. The barrier rib 280 is formed of a photosensitive insulating material such as a photosensitive resin. The barrier rib 280 is formed by applying and baking a photosensitive insulating material on the protective layer 224 and then irradiating light such as ultraviolet rays and developing the same.

In this case, a polymer organic material is added to the photosensitive insulating material for forming the partition wall 280. The polymer organic material is a polymer organic material including an ether component or n-aliphatic component, and the glass transistion temperature is lower than the baking temperature of the photosensitive insulating material for forming the partition wall 280. Therefore, when baking the photosensitive insulating material for forming the partition wall 280, the added polymer organic matter is transferred to the glass state and flows into the lower region inside the photosensitive insulating layer. As described above, since the partition wall 280 is very thick (about 10-100 μm), it is difficult to completely harden to the lower part of the insulating layer during baking, so that an uncured region is generated, which is developed by the uncured region. The city partition wall 280 is reverse tapered or undercut occurs. However, in this embodiment, since the polymer organic matter contained in the insulating layer is transferred to the glass by baking, moves to the lower region and is cured, the uncured region of the lower region of the insulating layer is cured by the polymer organic substance. The partition wall 280 may be prevented from reverse tapering or undercutting.

The polymer organic material is added within about 10% of the photosensitive insulating material forming the partition 280. When the polymer organic material is added to 10% or more, since the heat resistance decreases when the partition wall 280 is formed, the partition wall 280 is broken, and the polymer organic material is preferably added within about 10%.

Subsequently, as shown in FIG. 7C, an electrophoretic material is applied between the partitions 280 to form an electrophoretic layer 260, and then the electrophoresis is performed by the sealing layer 268 as shown in FIG. 7D. The electrophoretic display device may be completed by attaching the second substrate 240 having the sealing layer 260 and the common electrode 242 formed thereon to the first substrate 220.

In the electrophoretic display device of the present embodiment, by attaching an additive having a glass transition temperature lower than the baking temperature of the material forming the partition to the partition 280, the uncured area is prevented from occurring in the lower area during the pot baking. As a result, when the reverse taper is formed on the partition wall 280 or undercut is prevented from occurring, it is possible to effectively prevent the electrophoretic display device from becoming defective.

As described above, in the present invention, since the electrophoretic layer is directly formed on the first substrate, the electrophoretic layer is formed on the second substrate to protect the adhesive layer or the adhesive layer for attaching the electrophoretic layer to the second substrate. There is no need for a protective film. In addition, in the present invention, since the electrophoretic layer can be formed in a process line such as an existing thin film transistor forming process line, for example, an insulation layer, etc., a separate process line is not required, thereby further reducing manufacturing costs. do.

In addition, in the present invention, compared to the conventional manufacturing and transporting the electrophoretic layer in a separate factory or manufacturer to attach to the second substrate and the second substrate is bonded with the first substrate, in the present invention the transfer of the substrate on which the electrophoretic layer is formed Since the process such as the adhesion of the electrophoretic layer is not required, the manufacturing process can be simplified.

Furthermore, in the present invention, it is possible to prevent the occurrence of reverse taper or undercut in the partition wall during development of the partition wall, thereby preventing image quality defects caused by the reverse taper area and the undercut area.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

120,140 substrate 111 gate electrode
113: semiconductor layer 115: source electrode
116: drain electrode 118: pixel electrode
124: protective layer 142: common electrode
160: electrophoretic layer 164: white particles
165 black particles 168 sealing layer
180: partition 182: buffer layer

Claims (40)

Providing a first substrate and a second substrate including an image display unit including a plurality of pixels and an image non-display unit;
Forming a thin film transistor on the first substrate;
Forming a protective layer on the first substrate on which the thin film transistor is formed;
Forming a pixel electrode on the image display unit on the protective layer;
Forming a buffer layer on the non-image display unit on the protective layer;
Forming a partition on the buffer layer;
Forming an electrophoretic layer by filling an electrophoretic material in a pixel inside the barrier rib above the protective layer;
Forming a common electrode on the second substrate; And
An electrophoretic display device manufacturing method comprising the step of bonding the first substrate and the second substrate. The method of claim 1, wherein the forming of the buffer layer comprises:
Depositing a photosensitive organic material on the protective layer;
Baking the photosensitive organic material; And
Electrophoretic display device manufacturing method comprising the step of developing the photosensitive organic material. The method of claim 1, wherein the forming of the partition wall comprises:
Stacking a photosensitive organic material on a protective layer on which a buffer layer is formed;
Baking the photosensitive organic material; And
Electrophoretic display device manufacturing method comprising the step of developing the photosensitive organic material. The method of claim 1, wherein the barrier rib and the buffer layer are made of the same material. The method of claim 4, wherein the buffer layer is surface-treated before the barrier ribs are formed to improve wettability of the buffer layer. The method of claim 4, wherein the surface treatment of the buffer layer is performed by an oxygen plasma process, a hydrogen plasma process, or a SAM (Self Assembled Monolayer) coating process. The method of claim 1, wherein the barrier rib and the buffer layer are made of different materials. The method of claim 7, wherein the barrier ribs and the buffer layer are each formed of a material having a surface energy difference of 5 mN / m ² or less. The method of claim 1, wherein the buffer layer is formed to a thickness of 0.05-20 μm. The method of claim 9, wherein the buffer layer is formed to a thickness of 0.05-10 μm. The method of claim 10, wherein the buffer layer is formed to a thickness of 0.05-3 μm. The method of claim 1, wherein the electrophoretic material comprises white particles and black particles having charge characteristics. The method of claim 1, wherein the electrophoretic material comprises color particles having charge characteristics. The method of claim 12, wherein the electrophoretic material further comprises a dispersion medium. The electrophoretic material of claim 1, wherein the forming of the electrophoretic layer is performed by one of a dropping method, a squeeze method, a casting printing method, a bar coating printing method, a screen printing method and a mold printing method. Electrophoretic display device manufacturing method comprising the step of filling. The method of claim 1, further comprising forming a sealing layer to seal the electrophoretic material in the partition wall. The method of claim 16, wherein the sealing layer is formed over the entire first substrate. The method of claim 16, wherein the sealing layer is formed on the partition wall. The method of claim 1, wherein the bonding of the first substrate to the second substrate comprises forming an adhesive layer on at least one of the first substrate and the second substrate. The method of claim 1, wherein the forming of the thin film transistor comprises:
Forming a gate electrode on the first substrate;
Forming a semiconductor layer on the gate electrode;
Forming a source electrode and a drain electrode on the semiconductor layer. Providing a first substrate and a second substrate including an image display unit including a plurality of pixels and an image non-display unit;
Forming a thin film transistor on the first substrate;
Forming a protective layer on the first substrate on which the thin film transistor is formed;
Forming a pixel electrode on the image display unit on the protective layer;
Forming an insulating layer including an insulating material and an additive having a glass transition temperature lower than a baking temperature of the insulating material on the protective layer;
Baking the insulating layer;
Developing a baked insulating layer to form a partition on the image non-display portion on the protective layer;
Forming an electrophoretic layer by filling an electrophoretic material in a pixel inside the barrier rib above the protective layer;
Forming a common electrode on the second substrate; And
An electrophoretic display device manufacturing method comprising the step of bonding the first substrate and the second substrate. 22. The method of claim 21, wherein an additive flows under the insulating layer by baking the insulating layer. The method of claim 21, wherein the insulating material comprises a photosensitive resin. The method of claim 21, wherein the additive comprises a polymer organic material. 25. The method of claim 24, wherein the polymer organic compound comprises an ether component or an n-aliphatic component. 25. The method of claim 24, wherein the polymer organic material is included in the insulating layer within 10% of the insulating layer. First and second substrates including an image display unit and a non-image display unit including a plurality of pixels:
A thin film transistor formed on the first substrate;
A protective layer on the substrate on which the thin film transistor is formed;
A pixel electrode formed on the image display unit on the protective layer;
A buffer layer formed on an image non-display portion of the protective layer;
Barrier ribs formed on the buffer layer;
An electrophoretic layer formed inside the partition wall in the unit pixel; And
An electrophoretic display device comprising a common electrode formed on a second substrate. 28. The method of claim 27, wherein the thin film transistor,
A gate electrode formed on the substrate;
A semiconductor layer formed on the gate electrode; And
An electrophoretic display device comprising a source electrode and a drain electrode formed on the semiconductor layer. 28. The electrophoretic display device of claim 27, wherein the electrophoretic material comprises white particles and black particles having charge characteristics. 28. The electrophoretic display device of claim 27, wherein the electrophoretic material comprises color particles having charge characteristics. 31. The electrophoretic display device of claim 29 or 30, wherein the electrophoretic material further comprises a dispersion medium. 28. The method of claim 27, wherein the buffer layer is formed to a thickness of 0.05-20 탆. 33. The method of claim 32, wherein the buffer layer is formed to a thickness of 0.05-10 mu m. 34. The method of claim 33, wherein the buffer layer is formed to a thickness of 0.05-3 μm. 28. The method of claim 27, wherein the buffer layer and the partition wall are made of the same material. First and second substrates including an image display unit and a non-image display unit including a plurality of pixels:
A thin film transistor formed on the first substrate;
A protective layer on the substrate on which the thin film transistor is formed;
A pixel electrode formed on the image display unit on the protective layer;
Barrier ribs formed on the non-image display unit of the protective layer;
An electrophoretic layer formed inside the partition wall in the unit pixel; And
It is composed of a common electrode formed on the second substrate,
The partition wall is an electrophoretic display device comprising an insulating material and an additive having a glass transition temperature lower than the baking temperature of the insulating material. 37. The electrophoretic display device of claim 36, wherein the insulating material comprises a photosensitive resin. 37. The electrophoretic display device of claim 36, wherein the additive comprises a polymer organic material. The method of claim 38, wherein the polymer organic material comprises an ether component or an n-aliphatic component. 40. The method of claim 39, wherein the polymer organic material is included in the insulating layer within 10% of the insulating layer.

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