KR20050094283A - Color filter substrate and fabrication method therefor - Google Patents

Abstract

The present invention relates to a method for manufacturing a color filter substrate, wherein a step formed between a black matrix and an edge of a sub color filter region is formed by forming a black matrix on a substrate and then forming a color filter layer. Exposure is performed by applying a mask that includes a color filter layer from which the step is removed. As a result, a color filter layer having no step can be formed, and a flattening film forming process for compensating for the step of the color filter layer can be reduced.

Description

Structure of color filter substrate and its manufacturing method {COLOR FILTER SUBSTRATE AND FABRICATION METHOD THEREFOR}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a liquid crystal display device, and more particularly, to a color filter substrate using no flattening film and a method for manufacturing the same.

Today, liquid crystal display devices are in the spotlight as image display devices due to their light and simple characteristics. The liquid crystal display device is characterized in that it is a thin image display device, the research to manufacture the liquid crystal display device by a shorter process and the research to make the thin film image display device even more active.

A liquid crystal display device includes a liquid crystal panel that is a collection of a number of unit pixels. The liquid crystal panel usually includes a thin film transistor (TFT) array substrate in which a thin film transistor for driving unit pixels is arranged in a matrix, and the TFT array. It consists of a color filter substrate facing the substrate, and a liquid crystal filled between the two substrates.

The TFT array substrate includes a plurality of gate lines, a plurality of data lines perpendicularly intersecting the gate lines, and a TFT as switching elements formed at intersection regions of the gate lines and data lines. The unit pixel is defined by the vertical intersection of the gate line and the data line.

On the other hand, the color filter substrate facing the TFT array substrate includes a black matrix to block a part of the light propagating from the TFT array substrate, a sub color filter layer formed for each unit pixel defined by the black matrix, and the sub color. And a color filter layer formed by a set of filter layers, a planarization film for compensating for the steps formed by the color filter layer, a common electrode for applying an electric field to the liquid crystal, and an alignment film for determining the initial orientation of the liquid crystal.

Hereinafter, a manufacturing process of the color filter substrate expressing an image in color will be described with reference to FIGS. 1A to 1D.

 First, a black matrix forming material layer of a metal material or resin type for forming a black matrix is formed on the transparent substrate 101.

In general, the black matrix is formed between the sub color filter layers of red, green, and blue and is formed to block light passing through a reverse tilt domain formed at the periphery of the pixel electrode formed on the lower TFT array substrate. .

In general, as a material of the black matrix, a metal thin film such as chromium (Cr) having an optical density of 3.5 or more is used, or an organic material such as carbon is mainly used, and for the purpose of low reflection, chromium / chromium oxide ( A bilayer film such as Cr / CrOx) may be used.

When using a metal thin film as a material of the black matrix, it can be formed in a predetermined pattern through a photolithography process using a mask and an exposure process, and when using a resin of a photosensitive organic material, through an exposure process and a development process using a mask It can form a certain pattern.

In FIG. 1A, a black matrix 102 formed in a predetermined pattern on a substrate 101 is illustrated.

After the black matrix 102 is formed, as shown in FIG. 1B, a color filter layer 103 composed of red, green, and blue for representing an image in color is formed.

The color filter layer may be formed by a method such as a dyeing method, an electrodeposition method, a pigment dispersion method, or a printing method. As an example, a color filter layer manufacturing process by a pigment dispersion method will be described.

First, any one of red, green, and blue photosensitive color resins is applied to the entire surface of the substrate 101 on which the black matrix 102 is formed (in this case, red, green, and blue in order). The order of application of the color resin is irrelevant.) The red sub color filter layer 103a is formed in a desired area by selectively exposing.

Next, a green color resin is coated on the substrate 101 on which the red sub color filter layer 103a is formed, and a green sub color filter layer 103b is formed in a corresponding region through selective exposure. The blue sub color filter layer 103c is formed by repeating the above process for blue.

After forming the color filter layer 103, as shown in FIG. 1C, a transparent planarization film 104 of a transparent organic film component is formed to compensate for the step difference of the color filter layer 103.

After forming the planarization layer 204, a common electrode 105 made of indium tin oxide (ITO) or the like for applying an electric field to the liquid crystal layer is further formed.

Spacers 106 are formed on the common electrode 105 to maintain a constant cell gap of the liquid crystal display. The spacer may use a scattering method formed by spraying a ball-shaped spacer on a substrate and a pattern method capable of determining a constant size, height, and position.

The dispersion method can be divided into a wet dispersion method in which a spacer is mixed with an alcohol and sprayed, and a dry dispersion method in which only a spacer is dispersed. In addition, the dry dispersion method includes a dry dispersion method using static electricity and an antistatic dispersion method using gas pressure. The electrostatic dispersion method is mainly used for a liquid crystal cell structure that is vulnerable to static electricity.

Since the spreading method cannot determine the size, position, and height of the spacers to be spread, a column spacer forming method capable of increasing the aperture ratio is used.

In the column spacer forming method, a photosensitive spacer forming resin is coated on the common electrode, an exposure process is performed using a mask, and then a developing process and a cleaning process are performed to form a predetermined pattern. At this time, the mask process is required more.

After the column spacer is formed on the common electrode, an alignment layer 107 is formed by depositing an organic layer such as polyimide and rubbing in a predetermined direction for initial alignment of the liquid crystal.

As a result, the color filter substrate formation process of a liquid crystal display device is completed.

By the way, the manufacturing process of the said color filter substrate requires the mask process which requires many additional processes. In particular, in forming the color filter layer, a step occurs due to the color filter layer formed on the black matrix, and a planarization film forming process is further required to compensate for the step.

Therefore, an object of the present invention is to provide a method of manufacturing a color filter substrate without using a planarization film by reducing the step of the color filter layer formed on the black matrix due to the pattern of the black matrix.

In addition, an object of the present invention is to shorten the color filter substrate manufacturing process by manufacturing a color filter substrate without using a planarization film.

In addition, an object of the present invention is to provide a mask having a diffraction exposure portion formed in succession to the complete exposure portion to be able to align with a certain margin when forming a color filter layer to facilitate an easy mask alignment process.

As described above, the color filter substrate manufacturing method of the present invention to shorten the color filter substrate manufacturing process comprises the steps of forming a black matrix on the substrate; Forming a color filter layer by exposing a photosensitive color resin by applying a mask including a full exposure part and a diffraction exposure part on the black matrix; And forming a common electrode on the color filter layer.

Hereinafter, a method of manufacturing a color filter substrate of the present invention will be described with reference to FIGS. 2A to 2G.

Referring to FIG. 2A, the black matrix 202 is formed on the transparent substrate 201 in a constant pantone. The black matrix 202 may be made of a metal thin film or a resin of an organic component. In particular, the black matrix made of resin may have a large step.

The black matrix composed of a metal thin film can be thinly formed on a substrate, which is advantageous in the stepped surface, but can reduce the image quality by forming an unnecessary electric field in the liquid crystal sensitive to the electric field.

Therefore, the present invention is intended to solve the disadvantage that a step occurs when forming a color filter layer using a black matrix material, in particular resin.

First, in forming a black matrix, in the case of using a metal thin film as the material of the black matrix, a metal matrix is deposited on a substrate by a sputtering method or the like and a black matrix is formed in a matrix arrangement through a photolithography process.

That is, the photosensitive film is coated on the metal thin film formed on the substrate, and the exposure process, the developing process, and the cleaning process are performed by applying a mask having a black matrix pattern formed thereon.

On the other hand, when the photosensitive resin is used as the material of the black matrix, the photosensitive resin is coated on the substrate, and the black matrix is formed by exposing and developing by applying a mask having a black matrix pattern formed on the photosensitive resin.

When forming the resinous black matrix, in order to cure the resinous black matrix, hard baking may be further performed after the soft baking, the exposure and the developing process before the exposure.

As a result, in the sub color filter region 210 on the substrate 201, the substrate 210 is exposed and a black matrix is formed between the sub color filter regions. The black matrix is for blocking a part of the light propagating from the TFT array substrate and is manufactured using an opaque resin.

FIG. 2A illustrates one unit sub color filter region 210 and a black matrix 202 formed on both sides thereof. A unit sub color filter region 210 as illustrated in FIG. 2A is formed on a substrate 201. It is formed by three times the number of pixels. One unit pixel is constituted by three sub color filter areas.

Following the process of forming a black matrix on a substrate, a process of forming a color filter layer on the substrate 201 is performed.

The color filter layer is usually composed of red, green, and blue sub color filter layers. In an embodiment of the present invention, a color filter layer by a pigment dispersion method of applying a photosensitive color resin onto a substrate, exposing and developing the color filter layer to form a color filter layer It demonstrates centering on a manufacturing process.

As shown in FIG. 2B, a red first photosensitive color resin 203a is coated on the substrate 201 on which the black matrix 202 is formed. The photosensitive color resin is coated with a photosensitive resin on a substrate and rotates the substrate to uniformly apply the photosensitive resin onto the substrate, or a spinless coating using a rod type photosensitive resin applicator with a spray method. It can be applied onto the substrate by the method.

Since a black matrix is formed on the substrate 201, when the first photosensitive color resin 203a is applied onto the substrate 201, a step may occur when the first photosensitive color resin 203a crosses the black matrix 202. do.

The step makes it necessary to form a flattening film after forming the color filter layer.

The present invention forms a color filter layer by applying a mask having a diffraction exposure portion to solve the step difference caused by the photosensitive color filter resin formed on the black matrix.

This will be described in more detail with reference to FIG. 2B. The substrate 201 on which the black matrix is formed may be divided into a sub color filter region formed between the black matrix and the black matrix. The sub color filter area includes first, second, and third color filter areas of red, green, and blue. The first, second and third color filter regions form a unit to form one unit pixel. In FIG. 2B, only the first color filter area 210 is illustrated.

On the other hand, the mask 204 corresponding to the substrate 201 includes a complete exposure portion 204a corresponding to the first sub color filter region 210 on the substrate 201, the photosensitive color resin 203a, and black. The diffraction exposure portion 204b corresponding to the stepped region where the matrix 202 overlaps is formed. Light cannot transmit to the remaining areas of the mask except for the full exposure part and the diffraction exposure part.

The size of the complete exposure unit 204a may be the same as or smaller than the first sub color filter area 210 since the stepped area may start from an edge of the sub color filter area. In addition, the diffraction exposure portion 204b may be formed in the stepped region 220 including the black matrix and a portion of the first color filter region, and is formed in succession with the complete exposure portion 204a. In particular, the diffraction exposure unit 204b is preferably formed to have a predetermined size so as to correspond to the stepped region 220 generated when the photosensitive color resin crosses the black matrix.

Next, after the mask including the complete exposure portion 204a and the diffraction exposure portion 204b is arranged with the substrate 201, an exposure process is performed.

Soft baking may be further performed to dry the photosensitive first color filter layer 203a and to enhance adsorptivity on the substrate before exposing the first color filter layer 203a.

After exposing the first color filter layer 203a by applying the mask 204, the exposed first color filter layer 203a is developed. On the other hand, in the present embodiment, a negative photosensitive resin in which the photosensitive color filter layer to be exposed is cured is used. However, the type of photosensitive resin is not limited to the negative type.

As a result of using the negative photosensitive color filter layer, the photosensitive color filter layer of the first color filter region 210 completely exposed in the developing process remains cured and partially exposed through the diffraction exposure portion 204b of the mask 204. A portion of the first color filter layer 203a formed in the stepped region 220 is partially removed, and a portion thereof remains. However, the photosensitive first color filter layer on the partially exposed black matrix is greatly reduced in volume.

Among the first color filter layers 203a, the first color filter layer of the fully exposed first color filter region 210 and the partially exposed stepped region 220 remains, and the rest are removed in the developing process.

Next, the developed first color filter layer 203a is hard baked to be completely cured to form a first color filter layer. After the hard baking process, the substrate may be further subjected to a cleaning process.

In the process, the volume of the first color filter layer 203a on the partially exposed black matrix is reduced by a hard baking process. At this time, the volume of the first color filter layer of the stepped region 220 is also reduced to increase the level. It can be improved.

FIG. 2C shows the first sub color filter layer 203a1 formed after the first color filter layer 203a has been exposed and developed. FIG. 2D shows that the developed first sub color filter layer 203a1 is hard. After baking, the first sub color filter layer 203a1 with the step removed is shown.

Next, a green second color filter layer 203b is coated on the substrate 201 on which the first sub color filter layer 203a1 is formed, and a second sub color filter layer forming process is performed.

The process of forming the second sub color filter layer may be performed in the same manner as the process of forming the first sub color filter layer 203a1. That is, as shown in FIG. 2E, the green second color filter layer 203b is coated on the substrate 201 on which the first sub color filter layer 203a1 is formed, and the complete exposure portion 205a and the diffraction exposure portion 205b are applied. The exposure process is performed using the mask 205 containing (circle). Since the red sub color filter layer 203a1 and the green sub color filter layer 203b1 are formed in the same pattern on the substrate, the mask 205 may apply the mask used when forming the red sub color filter layer. A separate mask can also be applied.

Next, the exposed second color filter layer 203b may be removed and the step may be removed through the development process and the hard baking process.

Next, a process of forming a blue third sub color filter layer 203c1 on the substrate 201 on which the first sub color filter layer 203a1 and the second sub color filter layer 203b1 are formed is performed. The process of forming the third sub color filter layer may be performed in the same manner as the process of forming the first and second sub color filter layers.

That is, applying a third color filter layer on the substrate 201, exposing by applying a mask including a full exposure portion and a diffraction exposure portion, developing the third color filter layer, the developed third sub The color filter layer is subjected to hard baking and cleaning.

As a result, as shown in FIG. 2F, since the sub color filter layer is formed on the black matrix, the color filter layer from which the step difference is eliminated is completed.

Next, as shown in FIG. 2G, a common electrode 206 is formed on the color filter layer 203 to apply an electric field to the liquid crystal. Since the color filter layer 203 is removed by diffraction exposure of the color filter layer of the step area where the black matrix and the color filter layer overlap, the step may hardly occur, and thus the planarization film may not be used. In addition, it may not be necessary in the transverse electric field system which is a mode in which the common electrode 206 is not formed.

Therefore, in the present invention, the common electrode can be formed directly on the color filter layer. The common electrode may be formed by sputtering a conductive conductive indium tin oxide (ITO) or indium zinc oxide (IZO).

After the common electrode 206 is formed on the color filter layer 203, a spacer 207 is formed to maintain a constant cell gap between the color filter substrate and the TFT array substrate, which are spaces filled with liquid crystal.

The spacer 207 may be formed by a column spacer forming method capable of forming a spacer having a predetermined pattern and size at a predetermined desired position.

The column spacer forming method is a method of forming a spacer having a predetermined size and pattern at a predetermined position using a photosensitive resin, so that the spacer can be formed on the black matrix, which is suitable for manufacturing a color filter substrate having an improved aperture ratio.

Next, the color filter substrate of the present invention is completed by forming an alignment film 208 composed of polyimide or the like on the substrate 201 having the spacer and determining the initial alignment of the liquid crystal.

Therefore, the color filter substrate of the present invention includes a black matrix formed on a transparent substrate and a color filter layer formed on the black matrix and formed by perfect exposure and diffraction exposure, and having a step removed, and a common electrode directly contacting the color filter layer and the common electrode. And a spacer formed on the spacer and an alignment layer formed on the spacer.

Therefore, the color filter layer formed on the black matrix can be removed by applying a mask including the full exposure portion and the diffraction exposure portion and forming a color filter layer formed by the complete exposure and the diffraction exposure simultaneously, thereby obtaining a color filter layer having improved step height. Can be. Further, by forming the diffraction exposure portion in the outer portion successive to the complete exposure portion, the mask and the substrate can be easily aligned in the exposure process for forming the color filter layer. That is, the diffraction exposure portion can act as a margin of the sub color filter layer formation region, so that the alignment between the mask and the substrate is advantageous.

In addition, in the present invention, since the step is hardly generated in the color filter layer, the planarization film for compensating the step of the color filter layer may not be formed, thereby shortening the process. On the other hand, the present invention can apply the conventional color filter substrate manufacturing process almost as it is possible to manufacture a color filter substrate with improved step without the addition of production equipment.

1A to 1D are water purity diagrams illustrating a general color filter substrate manufacturing process.

2A to 2G are water purity diagrams showing the color filter substrate manufacturing process of the present invention.

***** Explanation of symbols on important parts of drawing *****

201: substrate 202: black matrix

210: first sub color filter area 203: color filter layer

203a, 203b, 203c: sub color filter layer

205: mask 205a: fully exposed part

205b: diffraction exposure section 206: common electrode

207: Spacer 208: alignment film

Claims (10)

Forming a black matrix on the substrate; Forming a color filter layer by exposing a photosensitive color resin by applying a mask including a full exposure part and a diffraction exposure part on the black matrix; Forming a common electrode on the color filter layer, characterized in that it comprises a color filter substrate manufacturing method. The method of claim 1, wherein the sub color filter layer of the photosensitive color resin is formed through the complete exposure unit. The method of claim 1, wherein the sub color filter layer of the stepped region overlapping the black matrix is partially exposed through the diffraction exposure unit. The method of claim 1, wherein the forming of the color filter layer Applying a first photosensitive color resin on the substrate on which the black matrix is formed; Soft baking the photosensitive color resin; Applying the mask to completely expose a first sub color filter region and diffractively expose the stepped region; Developing the exposed first photosensitive color resin; And planarizing the first photosensitive color resin by hard baking the developed first photosensitive color resin. The method of claim 4, wherein the forming of the color filter layer And forming a second sub color filter layer and a third sub color filter layer by applying the mask including a diffraction exposure part and a full exposure part on the substrate. The method of claim 1, wherein a part of the sub color filter region is diffracted through the diffraction exposure portion of the mask. The method of claim 1, further comprising forming a spacer on the common electrode. A black matrix formed on the substrate; A color filter layer including a complete exposure portion and a diffraction exposure portion formed on the substrate; And a common electrode formed on the color filter layer. The color filter substrate of claim 8, wherein the diffraction exposure part comprises a portion of a sub color filter region formed between a portion of the black matrix and the black matrix. 10. The color filter of claim 8, wherein the full exposure part is located in a sub color filter area formed between the black matrix and the diffraction exposure part is located at an edge of the sub color filter area and an upper portion of the black matrix. Board.