KR100675637B1 - Crystallization method for removing moire and method for fabricating display device using thereof - Google Patents

Abstract

The present invention relates to a crystallization method for removing a moire fringe in an image display device. The present invention relates to a unit formed on an array substrate during laser crystallization, focusing on the fact that the moire fringe is improved when a lattice generating the moire fringe forms a predetermined angle. The laser scanning direction is determined to have a predetermined angle with the pixel pattern, and the lattice pattern formed by the formed crystalline grain boundary is crystallized to have a predetermined angle with the unit pixel pattern.

Moiré, Crystallization, Scan Direction

Description

Crystallization method to remove moiré phenomenon and manufacturing method of image display device using same {CRYSTALLIZATION METHOD FOR REMOVING MOIRE AND METHOD FOR FABRICATING DISPLAY DEVICE USING THEREOF}

1 is a cross-sectional view showing a unit pixel of a conventional liquid crystal display device.

2A is a plan view of the crystalline formed by SLS crystallization.

2B is a cross-sectional view of the crystalline formed by SLS crystallization.

3 is a photograph of a moire fringe appearing on an image display device.

4 is a conceptual diagram showing a relationship between a moire fringe and a lattice.

5 is a photograph showing an experiment to remove the moire pattern.

6 is a graph showing the relationship between the angle between the moire fringe and the lattice.

7 is a plan view showing a crystallization method of the present invention.

8A to 8I are flowcharts illustrating a method of manufacturing an image display device according to an embodiment of the present invention.

********* Description of the symbols for the main parts of the drawings ***********

701: substrate 702: unit scan area

703: unit pixel 704: crystallization area

810: substrate 811: buffer layer

812,813 Active layer 814,816,818 Insulation layer

812b: Source area 812c: Drain area

815: gate electrode 817: storage electrode

819a: source electrode 819b: drain electrode

820, 822: protective layer 821: anode electrode

823: organic light emitting layer 824: cathode electrode

The present invention relates to a crystallization method of an image display device using polysilicon, and more particularly, to a crystallization method for removing moiré on a screen of an image display device.

With the active development of information processing apparatuses today, the development of image display apparatuses is also actively being made. In particular, the development of a liquid crystal display device (LCD) and an organic EL (Electro luminescence) device, which is light and simple and excellent in portability, is being actively performed.

The liquid crystal display device includes a liquid crystal display panel including an array substrate having unit pixels arranged in a matrix, a color filter substrate facing the array substrate, and a liquid crystal layer filled between the array substrate and the color filter substrate.

Referring to Figure 1 looks at the structure of the array substrate.

As illustrated in FIG. 1, a plurality of gate lines 101 and a plurality of data lines 102 perpendicular to the gate lines 101 are formed in the array substrate. A unit pixel region is defined by the intersection of the gate line 101 and the data line 102, and a thin film transistor 103, which is a switching element, is formed in each unit pixel region. In addition, a pixel electrode 105 for applying an electric field to the liquid crystal layer is formed for each unit pixel.

In general, the thin film transistor 103 uses amorphous silicon as the channel layer 104. In accordance with the demand for high-speed operation of the liquid crystal display, polysilicon having high electric mobility is actively developed.

The liquid crystal display using polysilicon as an active layer is classified into an excimer laser annealing method (ELA) and a sequential horizontal crystallization method (SLS) according to the crystallization method. The excimer laser annealing method (ELA) can obtain polysilicon having a large grain boundary by crystallizing the silicon by heating it to the near-melt region by laser. In the sequential horizontal crystallization method, a large-scale crystalline silicon grown horizontally in the lateral direction may be obtained by exposing a silicon layer to be crystallized through a slit, completely melting the exposed silicon layer and then crystallizing it.

However, in the crystallization methods, crystals soar upward at grain boundaries where crystalline and crystalline meet, and the grain boundaries forming the irregularities form a lattice pattern on a plane.

FIG. 2A shows a plan view of polysilicon crystallized by the SLS crystallization method, and FIG. 2B shows a side view of FIG. 2A.
2A and 2B, it can be seen that a concave-convex boundary is formed between the grain boundaries. The uneven afterimage of the grain boundary is formed not only in the active layer of the thin film transistor but also in the entire array substrate to form a lattice pattern. In addition, since the substrate on which the liquid crystal display panel is formed is large, it cannot be achieved by only one laser irradiation. Therefore, several laser shots must be irradiated to one substrate, and shot marks remain on the substrate by the laser shot.

As a result, the array substrate on which the thin film transistor is formed has at least a lattice pattern formed by the intersection of the gate line and the data line, a lattice pattern formed by the laser shot, and a lattice pattern formed by the grain boundary generated in the crystallization process. Three repeating patterns occur.

However, the repetitive pattern causes a problem of forming a negative moire pattern in image quality by acting as a slit of interference and diffraction of incident light when the LCD displays an image.

3 shows moiré patterns appearing on the surface of an organic EL image display device.

Moire refers to a pattern generated when a point or line is regularly distributed. For example, in tricolor or four-color printing, when each plate does not have the correct angle, staining occurs. This is called a moiré phenomenon, and when such a moiré phenomenon appears on the screen, there is a problem of degrading image quality.

Hereinafter, the moiré phenomenon will be described in more detail. Before we get to know Moiré, in order to understand the moiré phenomena, we need to first understand the beat phenomena of sound waves.

The beat phenomenon is that two waves of similar frequency affect each other, and the frequency width changes in a constant cycle according to the difference between the two frequencies. Waves with similar frequencies cancel and reinforce each other's frequencies to form a constant period. It is this cycle that causes the wave to grow or disappear.

The moiré phenomenon can be considered that the beat phenomenon occurs visually. If the objects have a certain distance, interference patterns are generated between them. Therefore, in a liquid crystal display panel, a gate line, a data line, a grain boundary, and the like that form a lattice form a moire pattern on a screen by acting as a slit for interference and diffraction of light. The moiré pattern may form a rainbow lattice or a comb-toothed lattice.

The moire pattern is a problem of an image display device such as a liquid crystal display device, and is particularly problematic in an organic EL image display device using an organic EL as a light emitting element.

An image display apparatus using an organic EL as a light emitting device includes a plurality of gate lines arranged in parallel with each other and a plurality of data lines perpendicular to the gate lines, and unit pixels are defined by the intersection of the gate lines and the data lines. Each of the unit pixels is similar to a liquid crystal display in that a thin film transistor is provided as a switching element.

However, since the organic EL image display device uses an organic EL that emits light as a light source, it does not need a backlight assembly, which is a light source of the liquid crystal display device, and expresses color by controlling the amount of light emitted from the organic EL by controlling voltage. There is a difference in that the liquid crystal layer used in the present invention is unnecessary, and the organic EL itself has red, green, and blue colors, so that the color filter layer of the liquid crystal display device for expressing natural colors is unnecessary.

Although the moire problem occurs in both the organic EL image display device and the liquid crystal display device, the moire phenomenon is more prominent since the organic EL has no polarizing plate used in the liquid crystal display device.

Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, the present invention is a crystallization method for removing the moiré phenomenon that can improve the moiré phenomenon appearing on the screen of the liquid crystal display and the organic EL image display device and the same Its purpose is to provide a video display device. In particular, the present invention provides a crystallization method for removing the moiré phenomenon that can remove the moiré phenomenon occurring in the organic EL image display device using polysilicon crystallized by the SLS crystallization method or ELA crystallization method as the active layer of the switching element and the same Its purpose is to provide a video display device.

In order to achieve the above object, a method of manufacturing an image display device includes: forming a plurality of gate lines on a substrate; Forming a plurality of data lines perpendicular to the gate lines; And crystallizing the amorphous silicon layer formed on the substrate so that the lattice pattern formed by the plurality of unit pixels defined by the intersection of the gate line and the data line and the scanning direction of light form a predetermined angle. .

In addition, the image display device manufacturing method of the present invention comprises the steps of forming a gate line on the substrate; Forming a gate insulating layer on the gate line; Forming an amorphous silicon layer on the gate insulating layer; Crystallizing the amorphous silicon layer so that the scanning direction of the irradiated light and the forming direction of the gate line form a predetermined angle for crystallization of the amorphous silicon layer; Patterning the crystallized silicon layer to form an active layer; And forming a source electrode and a drain electrode on the active layer, and forming a pixel electrode connected to the drain electrode.

In addition, the image display device of the present invention comprises: a first lattice pattern formed by a plurality of gate lines formed on a substrate and a plurality of data lines perpendicular to the gate lines; A second lattice pattern formed by grain boundaries of polysilicon formed on the substrate at a predetermined angle with the first lattice pattern; And a third lattice pattern formed by a shot mark generated by light irradiated onto the silicon layer formed on the substrate.

Moire occurs when light is interfered and diffracted by the lattice pattern. Referring to FIG. 4, the relationship between the lattice and the moire pattern will be described.

4 illustrates a parallel first linear pattern 401, a second linear pattern 402 having a predetermined angle 2α, and a first linear pattern 401 and a first linear pattern 401. The moire fringe 403 generated by the two linear patterns 402 is shown.

The first linear patterns 401 are arranged parallel to each other with a spacing of d1, and the second linear patterns 402 are arranged parallel to each other with a spacing of d2.

The linear moiré pattern 403 having an interval of d ₀ is generated by the first linear pattern 401 and the second linear pattern 402.

The relation between the first linear pattern 401, the second linear pattern 402, and the moire fringe 403 is represented as follows.

AB = d ₁ / sin (θ-α) = d ₂ / sin (θ + α)

CD = d ₁ / sin 2α = d ₀ / sin (θ + α)

(Formula 3) d ₀ = d ₁ d ₂ / (d ₁ ² + d ₂ ² -2d ₁ d ₂ cos2α) ^1/2

(4 expressions) θ = tan ^-1 (tanα (d ₁ + d ₂ / d ₂ -d ₁ ))

As shown in Equation 3, it can be seen that the spacing d ₀ of the moire fringe has a constant relationship with the angles 2α and d ₁ and d ₂ between the first linear pattern 401 and the second linear pattern 402. . That is, when the values of d ₁ and d ₂ are fixed, the interval between the moiré patterns becomes narrow when the angle 2α formed by the first linear pattern 401 and the second linear pattern 402 becomes large.

Since the human eye has a limited resolution, the moiré pattern may not be observed if the moiré pattern interval is less than the resolution of the eye.

In contrast to the result of the image display device having a gate line and a data line, the first linear pattern may correspond to a lattice pattern formed by the gate line and the data line, and the second lattice pattern is a laser generated during the crystallization process. It may be a grid of grain boundaries resulting from shot marks or crystallization.

Through the following experiments, we will examine the relationship between the linear pattern and the moire pattern forming a predetermined angle.

5 illustrates two image display panels overlapping each other. The image display panel may be a liquid crystal display panel or an organic EL image display panel. This experiment was conducted on the organic EL image display panel.

As illustrated in FIG. 5, the lattice patterns formed on each image display panel, that is, the lattice patterns formed by the gate lines and the data lines, form a predetermined angle with each other by overlapping the two image display panels.

Thus, the grid patterns formed on the image display panels overlap each other to form a predetermined angle, and the gap between the moire patterns generated while rotating one of the image display panels on the surface of the other image display panel was measured. That is, the first panel 501 and the second panel 502 of FIG. 5 overlap each other at a predetermined angle.

6 shows the relationship between the moire fringe spacing and the angle formed by the lattice pattern.

The x axis of FIG. 6 represents an angle 2α formed by the first panel 501 and the second panel 502, and the left y axis represents an angle formed by the second linear pattern 402 and the moire pattern 403, that is, the moire pattern. The generation angle of θ + α is shown, and the right y-axis shows the interval d ₀ between moire fringes.

As shown in the graph of Figure 6, it can be seen that the spacing of the moire pattern changes with the change of the angle between the two linear patterns.

As shown in FIG. 6, in the moire fringe, an area indistinguishable with the naked eye according to an angle formed by two intersecting linear patterns, that is, areas A and B of FIG. 6 appear.

In other words, the spacing of the moire fringes is changed by the angle between the two grids, and at a predetermined angle, the moiré can be formed with a fine moiré which cannot be distinguished by the naked eye. From the above results, it can be seen that the moire fringe can be improved when the lattice crossing each other has a predetermined angle.

In view of the above results, the present invention relates to a lattice, a gate line, and a data line formed by a lattice formed by a grain boundary formed by crystallization or a laser shot used for crystallization in an image display device using crystalline silicon as an active layer. Crystallization is performed so that the lattice to form a predetermined angle to prevent moiré generation.

Hereinafter, the crystallization method of the present invention will be described with reference to FIG. 7.

In the crystallization method of the present invention, the laser shot is performed such that the direction of the laser shot and the substrate 701 is at a predetermined angle.

As an example of the crystallization method of FIG. 7, the crystallization method employs an SLS crystallization method capable of obtaining a relatively large crystal quality.

In the SLS crystallization method, the laser shot direction and the crystallization direction tend to coincide, and the uneven grain boundary formed by the crystal meets and is formed to be perpendicular to the laser shot direction.

Referring to FIG. 7, a crystallization method for reducing moiré pattern generation is performed. The laser shot is formed at a predetermined angle without parallel to the direction of the substrate 701 to be crystallized and the laser shot irradiated for crystallization. To form crystallization. That is, the crystallization direction and the unit pixel pattern are formed to be shifted from each other. 7 shows the angle formed by the substrate 701 and the laser shot direction as 2α.

In addition, 702 of FIG. 7 shows the area crystallized by one laser shot, that is, the unit laser shot region 702. Also, the lattice pattern appearing on the substrate 701 represents the unit pixel 703 formed by the intersection of the gate line and the data line. 704 shows the grain boundary exhibited by SLS crystallization.

After depositing an amorphous silicon layer on the substrate 701 by a PECVD method or the like, the amorphous silicon layer is irradiated with a laser using a laser generator such as an excimer laser generator. The area irradiated by one laser shot is the unit laser shot area 702, which crystallizes the entire substrate while moving the laser generator or the substrate 701 in a predetermined direction.

In FIG. 7, the substrate is scanned from left to right. After crystallization is performed in the scan direction, the substrate or the laser generator is moved in the step direction to perform crystallization by laser shot again.

When the crystallization proceeds in this way, a shot pattern by a laser shot is generated on the substrate, and in detail, a lattice pattern by grain boundaries in crystalline is further formed. In the grid pattern formed by the grain boundary, the horizontal crystallization is often formed by the pattern of the uneven portion formed by the meeting of the grains.

Therefore, as shown in FIG. 7, according to the crystallization method of the present invention, the substrate 701 has a first lattice pattern formed by a gate line and a data line, and a second formed by a mark of a laser shot for crystallization. At least three plaid patterns of the plaid pattern and the third plaid pattern produced by the grain boundary resulting from the crystallization.

The first grid pattern pattern, the second grid pattern, and the third grid pattern pattern form a predetermined angle with each other.

Therefore, the gratings act as a grating for moiré generation, and at a predetermined angle, the moiré pattern spacing becomes less than the visual resolution so that the moiré pattern does not appear.

Hereinafter, a method of applying the crystallization method of the present invention and forming an array substrate using an organic EL as a light emitting device will be described with reference to FIGS. 8A to 8I.

As shown in FIG. 8A, a buffer layer 811 is formed on a transparent substrate 810, and an amorphous silicon layer is formed thereon. Thereafter, the amorphous silicon layer is crystallized by a laser crystallization method. The crystallization method may be an SLS crystallization method or an ELA crystallization method.

This embodiment adopts the SLS crystallization method as the crystallization method.

When the amorphous silicon layer is crystallized to form a polycrystalline silicon layer, the polycrystalline forms a grain boundary pattern in a predetermined direction and forms a concave-convex pattern at the point where the grain boundary meets as shown in FIG. 7. In view of the plan view of the concave-convex pattern, a certain lattice pattern is formed on the substrate.

Subsequently, the polycrystalline silicon is applied and patterned to form island type active layers 812 and 813.

Subsequently, as shown in FIG. 8B, an insulating layer such as a silicon oxide film is deposited on the active layers 812 and 813 and a conductive material such as a metal is deposited thereon, followed by patterning using a second mask. The insulating layer 814 and the gate electrode 815 are formed. At this time, the gate line is simultaneously formed when the gate electrode is formed. The gate line is formed such that the lattice formed between the gate line formation direction and the uneven pattern forms a predetermined angle.

Subsequently, the gate electrode 815 is applied as a mask and impurity ions are implanted into the active layers 812 and 813 to form source and drain regions 812a and 812b and a capacitor electrode 813a. The source and drain regions 812a and 812b are formed at both sides of the active layer.

Subsequently, as shown in FIG. 8C, a first interlayer insulating layer 816 is formed on the gate electrode 815, a conductive material such as a metal is deposited thereon, and then a third mask is applied and patterned to form a capacitor electrode. A storage line 817 is formed on the upper portion 813a. The storage line 817 together with the capacitor electrode 813a forms a storage capacitor.

Subsequently, as shown in FIG. 8D, the second interlayer insulating layer 818 is formed on the storage line 817 and patterned by applying a fourth mask to the first to third contact holes 818a, 818b, and 818c. To form. The first contact hole 818a exposes the drain region 812b, the second contact hole 818b exposes the source region 812c, and the third contact hole 818c exposes the storage line 817. Expose

Next, as shown in FIG. 8E, a conductive material such as a metal is deposited on the second interlayer insulating layer 818 and patterned with a fifth mask to form a drain electrode 819b. The drain electrode 819a is connected to the drain region 812b through the first contact hole 818a, and the source electrode 819b is connected to the source region 812c and the storage through the second and third contact holes 818b and 818c. Connected to lines 817, respectively.

Next, as shown in FIG. 8F, a first passivation layer 820 is formed on the drain electrode 819a and the source electrode 819c and patterned with a sixth mask to expose the drain electrode 819a. The fourth contact hole 820a is formed.

Subsequently, as illustrated in FIG. 8G, an anode electrode (not shown) connected to the drain electrode 819a through the fourth contact hole 820a is formed by depositing a transparent conductive material and patterning the seventh mask. 821).

Next, as shown in FIG. 8H, a bank 822a exposing the anode electrode 821 by forming a second passivation layer 822 on the anode electrode 821, applying an eighth mask, and patterning the pattern to expose the anode electrode 821. To form.

Subsequently, as shown in FIG. 8I, an organic light emitting layer 823 is formed on the bank 822a of the second protective layer 822, and an opaque conductive material such as metal is deposited thereon to form a cathode electrode ( 824).

The above method shows an example of a manufacturing process of the organic EL image display device, wherein the lattice pattern formed by the gate line and the data line and the lattice pattern formed by the grain boundary generated during crystallization have a predetermined angle. This can reduce moiré phenomena caused by light interference and diffraction.

Although the SLS crystallization is used as the crystallization method in the above embodiment, the present invention may also be achieved by the ELA crystallization method to form a certain lattice pattern. Furthermore, in the above embodiment, a crystallization method for reducing moiré generated in the organic EL image display device is introduced, but the present invention can be applied to a liquid crystal display device.

As described above, the present invention relates to a lattice pattern formed by a grain boundary and a gate line and data formed on a substrate in an image display apparatus in which a grain boundary pattern is generated by crystallization of an organic EL image display device and a liquid crystal display device. The grid pattern formed by the lines is formed to form a predetermined angle to prevent the generation of moire fringes. The moire fringes deteriorate the image quality, and the present invention can remove the moire fringes and improve the image quality only by adjusting the crystallization direction without a separate process.

Claims (21)

Forming a plurality of gate lines on the substrate; Forming a plurality of data lines perpendicular to the gate lines; And A lattice pattern formed by a plurality of unit pixels defined by the intersection of the gate line and a data line through crystallization of a silicon layer and a lattice pattern formed by a grain boundary formed by crystallization of a silicon layer or a lattice pattern formed by a laser shot mark. Silicon crystallization method comprising the step of making a predetermined angle. The silicon crystallization method of claim 1, wherein the crystallization method of the silicon layer is selected from an SLS crystallization method or an ELA crystallization method. delete delete delete The silicon crystallization method of claim 1, wherein the lattice pattern formed by the grain boundary is formed by a concave-convex pattern generated in the impact portion of the grain boundary as a result of crystallization. delete Forming an amorphous silicon layer on the substrate; Irradiating a laser moving in a predetermined direction to the substrate to form a grid pattern formed by a grain boundary formed by crystallization of the amorphous silicon layer or a grid pattern formed by a laser shot mark; Patterning the crystalline silicon layer to form an active layer; Forming a gate line having a predetermined angle with the grid pattern formed by the grain boundary formed by the silicon crystallization or the grid pattern formed by the laser shot mark, and a gate electrode branching from the gate line on the substrate; Forming an interlayer insulating layer on the gate line; Forming a contact hole on the interlayer insulating layer to expose source and drain regions of the active layer; And And forming source and drain electrodes connected to the source and drain regions through the contact hole. delete delete The method of claim 8, wherein a data line perpendicular to the gate line is further formed when the source electrode is formed. The method of claim 11, wherein the gate line and the data line form a grid pattern on a substrate. The method of claim 12, wherein the grating pattern forms a predetermined angle that is not perpendicular to the laser movement direction. The method of claim 8, wherein the crystallization method is selected from an SLS crystallization method or an ELA crystallization method. delete The image display apparatus of claim 8, wherein the lattice pattern formed by the laser shot mark forms a predetermined angle that is not perpendicular to the lattice pattern formed by the gate line and the data line perpendicular to the gate line. Manufacturing method. A first lattice pattern formed by a plurality of gate lines formed on a substrate and a plurality of data lines perpendicular to the gate lines; A second lattice pattern formed by grain boundaries of polysilicon formed on the substrate at a predetermined angle with the first lattice pattern; And And a third lattice pattern formed by a laser shot mark generated by light irradiated onto the silicon layer formed on the substrate. delete 18. The image display device of claim 17, wherein the first grid pattern and the third grid pattern form a predetermined angle, not vertical. 18. The video display device of claim 17, wherein the spacing of the moire fringes generated by the lattice fringes is less than or equal to visual resolution. 21. The video display device of claim 20, wherein the video display device uses an organic light emitting display device as a light source.

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