KR20070080476A - 3 Manufacturing method of liquid crystal display device by mask process - Google Patents

Abstract

Method for manufacturing a liquid crystal display according to the third mask process according to the invention the first conductive film, and then laminating a first metal layer, the first mask process and the second to form the common electrode and the gate electrode by patterning a predetermined portion on the substrate After forming an insulating layer, an active layer, an ohmic layer, and a second metal layer on the result of the first mask process, patterning a predetermined portion to form a thin film transistor, and a protective layer formed on the result of the second mask process And a third mask process of patterning a predetermined portion to form a contact hole, stacking a second conductive film, and then lifting off to form a pixel electrode. As described above, the present invention reduces the process time and reduces the manufacturing cost by reducing the mask process from six to three steps in the manufacturing process of the conventional fringe field switching liquid crystal display using a method of properly combining the slit mask and the lift-off method. This is possible.

Description

Manufacturing method of liquid crystal display device by 3 mask process {METHOD FOR FABRICATING LIQUID CRYSTAL DISPLAY USING 3-MASK PROCESS}

1 is a view showing a fringe field switching type liquid crystal display device manufactured according to the present invention.

2 is a view illustrating a pixel electrode of a fringe field switching liquid crystal display device manufactured according to the present invention.

3 is a view showing a first mask process of a liquid crystal display according to the present invention.

4 is a view showing a second mask process of the liquid crystal display according to the present invention.

5 to 9 illustrate a third mask process of the liquid crystal display according to the present invention.

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

100 ... substrate 101 ... common electrode

102 gate electrode 103 insulating layer

104 ... active layer 105 ... ohmic layer

106 ... source electrode 107 ... drain electrode

108 ... protective layer 210 ... first mask

220 .... the second mask 230 ... the third mask

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a liquid crystal display device by a three mask process, and more particularly, to a method of manufacturing a liquid crystal display device of a fringe field switching mode using only three masks.

Disadvantages such as narrow viewing angle, slow response speed, and high manufacturing cost are rapidly improved due to mass production and development of technology, and advantages such as high resolution, light weight, and low power consumption are changed in ubiquitous and convergence technology environments. It is rapidly replacing CRT type display as it is emerging as an important technology element.

Currently, the liquid crystal display used is mainly a twisted nematic (TN) method and a super twisted nematic (STN) method to which an electric field in a vertical direction is applied. However, the TN and STN type liquid crystal display devices have a narrow viewing angle, and thus a liquid crystal display device having an in-plane switching mode (IPS) has been proposed.

The lateral electric field system has a structure in which a pixel electrode and a common electrode for driving liquid crystal molecules are arranged in parallel with each other on the same substrate. As a result, an electric field is formed parallel to the surface of the substrate when voltage is applied. Accordingly, the liquid crystal molecules are twisted in parallel with the electric field so that the user sees the long axis of the liquid crystal molecules in any direction, thereby improving the viewing angle of the liquid crystal display device. do.

 However, since the lateral electric field system is formed by overlapping the pixel electrode and the common electrode in the pixel area, there is a limit in the improvement of the aperture ratio and the transmittance, and thus a fringe field switching liquid crystal display device has been proposed.

The fringe field switching scheme is similar in structure to the transverse electric field scheme, but has a plurality of branches in which pixel electrodes are branched in parallel, thereby improving aperture ratio and transmittance characteristics. In addition, since a parabolic electric field is formed on the surface of the substrate when voltage is applied, the viewing angle is further improved.

The fringe field switching type liquid crystal display device is manufactured in the following manner.

First, a transparent conductive film is deposited on a transparent substrate, and a predetermined portion is patterned to form a common electrode (first mask process), a metal layer is additionally deposited, and then a predetermined portion is patterned to simultaneously form a gate electrode and a gate line. 2 mask process)

Subsequently, a gate insulating film, an active layer, and an ohmic layer are successively deposited to form a semiconductor three-layer film, and then the ohmic layer and the active layer are patterned to define a thin film transistor region (third mask process), and then a metal layer is deposited thereon. Partial patterning is performed to simultaneously form source / drain electrodes and data lines (fourth mask process).

Next, after forming a protective film on the substrate resultant, a contact hole is formed in a predetermined region (fifth mask process), a pixel electrode layer is formed in contact with the drain electrode through the contact hole, and then patterned to form a pixel electrode. (Sixth mask process).

As such, the fringe field switching method involves a total of six mask processes to manufacture a liquid crystal display. As is known, the mask process is a long time complicated process consisting of a series of processes such as photoresist coating, exposure, development, etching, photoresist peeling, and cleaning, and occupies most of the processes for manufacturing a liquid crystal display device. Therefore, most manufacturers are trying to improve the productivity of liquid crystal displays by reducing the mask process.

In conclusion, since the fringe field switching method of the related art has to involve a six-step mask process, there is a disadvantage in terms of manufacturing time and manufacturing cost in comparison with the IPS method, which is usually composed of a 4 to 5 mask process, and thus manufacturing a general liquid crystal display device. There was a limit to use in the process.

According to the present invention, a thin film is deposited on a slit mask and a pre-formed photoresist pattern which simultaneously perform three areas of non-exposure, front exposure, and partial exposure with one mask, and then remove the photoresist to obtain a final thin film. By replacing the conventional unit mask process with a method of properly combining the lift off method of forming a pattern, the number of mask processes required in manufacturing a fringe field switching liquid crystal display device is reduced by three steps, and thus the process An object of the present invention is to propose a method of manufacturing a three-mask liquid crystal display device, which can reduce time and manufacturing cost.

According to an aspect of the present invention, there is provided a method of manufacturing a liquid crystal display device using a three-mask process, in which a first conductive film and a first metal layer are stacked on a substrate, and then patterned to form a common electrode and a gate electrode. The result of the second mask process and the second mask process of forming a thin film transistor by forming a predetermined portion after laminating an insulating layer, an active layer, an ohmic layer, and a second metal layer on the result of the first mask process and the first mask process. And forming a contact hole by forming a protective layer on the protective layer, forming a contact hole, stacking a second conductive layer, and then lifting the second electrode to form a pixel electrode.

Here, the first mask process, the first mask process, the first conductive film, the first metal layer on the substrate and the step of further coating the photoresist by coating the photoresist, single exposure, partial exposure, non-exposure Forming a gate electrode by etching the first conductive layer and the first metal layer in the front exposure region; and removing the photoresist in the partial exposure region, and etching the first metal layer to form a common electrode. It is characterized by including.

The second mask process may include stacking an insulating layer, an active layer, an ohmic layer, and a second metal layer on a substrate on which a gate electrode and a common electrode are formed, and additionally coating a photoresist to expose the front surface and the partial exposure. Performing a non-exposure process, defining a source / drain electrode region by etching the second metal layer of the front exposure region, and removing the photosensitive layer of the partial exposure region, and etching the second metal layer to form the source / drain electrode. It further comprises a step.

The third mask process may include forming a protective layer on the substrate on which the thin film transistor is formed, and further coating the photoresist to perform front exposure, partial exposure, and non-exposure with a single mask. Forming a contact hole by etching the protective layer, removing the photosensitive layer of the partial exposure region, depositing a second conductive layer, and lifting the second conductive layer to form a pixel electrode. do.

The first and second conductive films are formed of a transparent conductive film such as ITO, IZO, or the like, and the pixel electrode is preferably formed of a metallic material having good conductivity.

The gate electrode is formed on the first conductive layer, the common electrode and the pixel electrode are insulated by an insulating film therebetween, and the pixel electrode includes a plurality of branches branched parallel to each other and a body connecting one end thereof. .

The mask may be a slit mask (or halftone mask) capable of front exposure, partial exposure, and non-exposure at the same time.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a fringe field switching type liquid crystal display device manufactured according to the present invention.

Referring to FIG. 1, the liquid crystal display includes a thin film transistor having a gate electrode 102, a source electrode 106, and a drain electrode 107, and a common electrode 101 and a pixel electrode 120 forming an electric field in the liquid crystal layer. ) And the like.

The gate electrode 102 extends to one side to form a gate line (not shown), and the drain electrode 107 extends in a direction crossing the gate line to form a data line (not shown). In this case, the gate line and the data line are insulated from each other by the insulating layer 103, and a plurality of gate lines and a plurality of data lines are formed on the substrate 100 to cross each other to define unit pixels. In this case, the gate line and the data line may be formed of a metal film or any two or more alloy films selected from the group consisting of Al, Mo, Ti, W, Ta, Cr, and combinations thereof having excellent conduction characteristics in order to reduce the RC delay. Can be.

The common electrode 101 is formed in each unit pixel space of the lower substrate 100. The common electrode 101 is formed on the same surface as the gate line, that is, the lower substrate 100, and is connected to the common signal line to receive the common signal.

The pixel electrode 110 is formed to face the common electrode 101 and the insulating layer 103 therebetween, and is connected to the drain electrode 107 through a contact hole 109 to receive a data signal. In this case, the pixel electrode 110 is a body (120e) connecting the plurality of branches (120a, 120b, 120c, 120d) branched in parallel with one end of the branches (120a, 120b, 120c, 120d) as shown in FIG. ) Has a structure including. 2 is a view showing a pixel electrode of a fringe field switching liquid crystal display device manufactured according to the present invention.

In addition, the common electrode 101 and the pixel electrode 110 are formed of a transparent conductive material such as ITO or IZO, which increases the area opened in the unit pixel, thereby improving the aperture ratio and transmittance.

The liquid crystal display having such a structure can firstly reduce the conventional first, second, third and fourth processes by two steps by using a slit mask, and secondly, by using a slit mask and a lift-off method. The fifth and sixth processes can be reduced to one step. That is, it can be manufactured through a three-step mask process, the advantage is to achieve the most important technical features in the present invention.

The slit mask is a method of exposing through a narrow line of slit, not directly exposing to the area to be exposed. Compared with the general exposure, the amount of light is reduced and the photoresist is partially exposed due to the effect of diffraction and the like, so that a thin layer of photoresist is left to make three areas of non-exposure, front exposure and partial exposure as one mask. In the case of using this mask, the portion where the pattern is formed by the front exposure can be etched first, and then the photoresist of the partial exposure area can be etched back, so that the mask of step 2 can be reduced to 1 step. There are advantages to it.

The lift-off method is a technique of forming a final thin film pattern by forming a pattern in a photoresist before depositing a thin film, depositing a thin film thereon, and removing the photoresist, and dissolving it in a solvent to remove the photoresist. By removing the thin films deposited on the photoresist to form a desired thin film pattern.

First, the first mask process will be described below.

3 is a view showing a first mask process of the liquid crystal display according to the present invention.

Referring to FIG. 3, a transparent conductive film is deposited on a transparent substrate 100, for example, a glass substrate or a quartz substrate. Transmissive conductive materials such as ITO and IZO may be selected as the transparent conductive film. The metal layer is deposited thereon, for example, by sputtering, and then coated with a photoresist, and exposed using the first mask 210. Here, the blocking part 210A is formed in the first mask 210 to correspond to the gate electrode 102 and the gate line (not shown) area, and the intermediate part 210B is formed to correspond to the common electrode area. The permeation | transmission part 210C is formed in the remaining area. Since the intermediate portion 210B has a slit shape and only a part of the light is transmitted, only about 25% of the photoresist in the corresponding region remains when developed, for example, in the case of a positive type in which the exposed region is removed.

Subsequently, when the photoresist of the blocking portion 210A and the intermediate portion 210B is etched as a barrier, the common electrode region is defined on the substrate 100, and the gate electrode 102 and the gate line are simultaneously formed. . Subsequently, the common electrode 101 is formed by etching back the photoresist of the intermediate portion 210B and etching the metal layer formed on the common electrode region using the photoresist of the blocking portion 210A as a barrier.

Next, the second mask process will be described.

4 is a view illustrating a second mask process of the liquid crystal display according to the present invention.

Referring to FIG. 4, the gate insulating layer 103 is coated on the resultant of the first mask process, and the active layer 104 made of amorphous silicon crystals and the ohmic layer 105 made of doped amorphous silicon crystals are successively coated. And stacked to form a semiconductor three-layer film, the metal films 106 and 107 are further stacked on the photoresist, and then the photoresist is coated and exposed using the second mask 220. Here, the blocking portion 220A is formed in the second mask 220 so as to correspond to the source / drain electrode region, and the intermediate portion 220B is formed so as to correspond to the source / drain isolation region, and the transmissive portion 220C is formed in the remaining region. ) Is formed.

Subsequently, the metal layers 106 and 107 are dry-etched using the photoresist of the blocking portion 220A and the intermediate portion 220B as a barrier, and the wetted ohmic layer 105 and the active layer 104 are wet-etched. The thin film transistor region and the source / drain electrode region are limited to 100, and data lines (not shown) are simultaneously formed. Subsequently, the photoresist of the intermediate portion 220B is etched back, and the source / drain electrode regions are partially etched by using the photoresist of the blocking portion as a barrier to form the source / drain electrodes 106 and 107. As a barrier, the lower ohmic layer 105 is etched to form a thin film transistor.

Here, the data lines are formed in plural and arranged to intersect with the plural gate lines, respectively, and the unit pixel is defined by an intersection area of the pair of gate lines and the data lines. Thin film transistors are arranged in one-to-one correspondence with each unit pixel.

Next, the third mask process will be described.

5 to 9 illustrate a third mask process of the liquid crystal display according to the present invention.

After the second mask process is finished, the protective film 108 is coated on the resultant, and then the photoresist 110 is further coated thereon. In this case, since the photoresist 110 must go through a subsequent lift-off process, it is preferable to form the photoresist thicker so that a relatively large step pattern can be formed in the photoresist 110.

Subsequently, the transmissive part 230C is formed to correspond to the contact hole area, the intermediate part 230B is formed to correspond to the pixel electrode pattern, and the third mask 230 having the blocking part 230A is formed in the remaining area. The photoresist 110 is exposed.

Since the pixel electrode pattern needs to form a parabolic electric field, that is, a fringe field electric field, together with the common electrode 101, the plurality of branches 120a, 120b, 120c, and 120d are formed in a bar body. 120e), and is formed in a lift-off manner. Therefore, an exposure pattern including a slit region and a blocking region should exist in the middle portion 230B of the third mask 230 to correspond to the pixel electrode pattern. In this case, the slit region is a portion that is partially exposed by using diffraction and overlap of light, and corresponds to the branches (120a, 120b, 120c, 120d of FIG. 2) and the body 120e of the pixel electrode.

When the exposure is performed through the third mask 230 having the above structure and developed, the photoresist 110 is removed from the contact hole region as shown in FIG. 6, and the pattern of the pixel electrode to be formed in the pixel electrode region is illustrated. In response to this, the photoresist 110 partially remains. Therefore, when the protective layer 108 is etched using the photoresist 110 as a barrier, a contact hole is formed which is connected to the drain electrode 107 as shown in FIG. 7.

Subsequently, as shown in FIG. 8, the partially exposed photoresist 110 is removed (ecth back), and then a transparent conductive film 120 is deposited thereon. In this case, in the pixel electrode region, the transparent conductive film 120 is deposited on the branches (120a, 120b, 120c of FIG. 2) and the body 120d, with the photoresist 110 removed thereon, and in the remaining regions. The transparent conductive film 120 is deposited thereon with the photoresist 110 remaining.

Subsequently, when the photoresist 110 existing on the substrate 100 is dissolved and removed by using an organic solvent, for example, a solvent solution, the transparent conductive film 120 formed on the photoresist 110 is formed as shown in FIG. 9. It is separated and removed, and the transparent conductive film remains only in the contact hole and the pixel electrode region in a predetermined pattern to form the pixel electrode 120.

The operation of the liquid crystal display will be described with reference to FIG. 1.

When the scan signal is applied to the gate line and the driving signal is applied to the data line, the thin film transistor formed near the intersection point of the gate line and the data line is turned on and transferred to the pixel electrode 120. In this case, since the common signal having a predetermined voltage difference is continuously applied to the common electrode 101, an electric field is formed between the common electrode 101 and the pixel electrode 120.

 On the other hand, since the pixel electrode 120 has a branched structure, a plurality of parabolic fringe fields are generated in the formed electric field. Since the starting point and the end point of the fringe field are edges of the electrodes 101 and 120, the liquid crystal molecules on the electrodes 101 and 120 operate under the influence of an electric field. In this case, the long axis of the liquid crystal molecules is twisted in parallel along the parabolic electric field, and the long axis of the liquid crystal molecules has a wide viewing angle characteristic. In addition, since the common electrode 101 and the pixel electrode 120 positioned in the image region to generate an electric field are formed of a transparent material, the aperture ratio characteristics are improved.

As described above, the above embodiments are disclosed for purposes of illustration, and those skilled in the art will appreciate that various modifications, improvements, substitutions, and additions may be made without departing from the spirit of the present invention. Accordingly, the technical scope of the present invention is defined by the appended claims.

As described above, the manufacturing method of the three-mask liquid crystal display device according to the present invention is a method of properly combining the slit mask and the lift-off method, and the six steps of the mask process in the manufacturing process of the conventional fringe field switching type liquid crystal display device. By reducing the process to three steps, the process time and manufacturing cost can be reduced.

In addition, the liquid crystal display manufactured by using the present invention has a pixel electrode and a common electrode formed of a transparent material, and a parabolic fringe field electric field is formed between the two electrodes, thereby improving aperture ratio and viewing angle to provide high brightness and high quality characteristics. do.

Claims (9)

A first mask process of forming a common electrode and a gate electrode by laminating a first conductive film and a first metal layer on a substrate and patterning the predetermined portion; A second mask process of forming a thin film transistor by stacking an insulating layer, an active layer, an ohmic layer, and a second metal layer on the resultant of the first mask process and patterning a predetermined portion; And And a third mask process of forming a contact hole by forming a protective layer on the resultant of the second mask process, patterning a predetermined portion, stacking the second conductive film, and then lifting off to form a pixel electrode. The manufacturing method of the liquid crystal display device by a 3 mask process. The method according to claim 1, The first mask process, Stacking a first conductive film and a first metal layer on the substrate; Further coating the photoresist to perform front exposure, partial exposure and non-exposure with one mask; Etching the first conductive layer and the first metal layer in the front exposure region to form a gate electrode; And Removing the photoresist of the partial exposure region and then etching the first metal layer to form a common electrode; Method of manufacturing a liquid crystal display device by a three-mask process further comprising. The method according to claim 1, The second mask process, Stacking an insulating layer, an active layer, an ohmic layer, and a second metal layer on the substrate on which the gate electrode and the common electrode are formed; Further coating the photoresist to perform front exposure, partial exposure and non-exposure with one mask; Etching the second metal layer of the front exposure region to define a source / drain electrode region; And Removing the photosensitive layer of the partial exposure region and then etching the second metal layer to form a source / drain electrode; Method of manufacturing a liquid crystal display device by a three-mask process further comprising. The method according to claim 1, The third mask process is Forming a protective layer on the substrate on which the thin film transistor is formed; Further coating the photoresist to perform front exposure, partial exposure and non-exposure with one mask; Etching the passivation layer of the front exposure region to form a contact hole; Removing the photosensitive layer of the partial exposure region and then depositing a second conductive film; And Lifting off the second conductive layer to form a pixel electrode; Method of manufacturing a liquid crystal display device by a three-mask process further comprising. The method according to claim 1, And the first and second conductive films are transparent conductive films. The method according to claim 1, And the pixel electrode comprises a plurality of branches branched in parallel. The method according to claim 6, And the pixel electrode further comprises a body connecting one end of the branches to the pixel electrode. The method according to claim 1 or 2, And the gate electrode is formed on the first conductive film. The method according to any one of claims 1 to 5, And the mask is a slit mask capable of front exposure, partial exposure and non-exposure at the same time.

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