KR100701667B1 - Semi-transmissive liquid crystal display device and manufacturing method - Google Patents

Abstract

The present invention discloses a semi-transmissive liquid crystal display device and a method of manufacturing the same, which can reduce the number of mask processes and improve gray scale implementation characteristics. Disclosed is a semi-transmissive liquid crystal display having a reflective electrode for displaying an image with ambient light and a transmissive portion for displaying an image with light of a backlight, comprising: a lower substrate and an upper substrate facing each other; A thin film transistor formed on the lower substrate and including a gate electrode, a channel layer, an active layer, and a source / drain electrode; An organic resin film formed on the lower substrate such that thicknesses of the reflection part and the transmission part are different from each other; A transmissive electrode formed on the organic resin film to be in contact with the thin film transistor; A reflective electrode formed on the reflective portion of the lower substrate and formed on the transmission electrode; A common electrode formed on the upper substrate; And a liquid crystal layer interposed between the lower substrate and the upper substrate.

Description

Transflective type liquid crystal display and method for manufacturing the same

1 is a cross-sectional view showing a conventional transflective liquid crystal display device.

2 is a cross-sectional view illustrating a transflective liquid crystal display device according to an exemplary embodiment of the present invention.

3A to 3F are cross-sectional views of processes for describing a method of manufacturing a transflective liquid crystal display according to an exemplary embodiment of the present invention.

4A to 4F are cross-sectional views of processes for explaining a sixth mask process according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

21: lower substrate 22: gate electrode

23 gate insulating film 24 channel layer

25: ohmic contact layer 26: source electrode

27 drain electrode 28 protective film

30 organic resin film 31 transmissive electrode

32: reflective electrode 40: liquid crystal layer

44: upper substrate 45: color filter

46: common electrode

The present invention relates to a transflective liquid crystal display device and a manufacturing method thereof, and more particularly, to a transflective liquid crystal display device and a method of manufacturing the same, which can reduce the number of mask processes and improve gray scale implementation characteristics.

The liquid crystal display may be classified into two types: a transmissive liquid crystal display using a backlight as a light source and a reflective liquid crystal display using natural light as a light source.

Since the transmissive liquid crystal display uses a backlight as a light source, it can implement a bright image even in a dark environment, but has a disadvantage in that power consumption is high by using a backlight. On the other hand, the reflective liquid crystal display device consumes a small amount of power because it uses natural light in the surrounding environment without using a backlight, but has a disadvantage in that it is impossible to use it in a dark environment.

Therefore, a semi-transmissive liquid crystal display device has been proposed to solve the above problems. Since the transflective liquid crystal display device can use both a reflection type and a transmissive type as needed, it has a relatively low power consumption and can be used even in a dark environment.

1 is a cross-sectional view of a conventional transflective liquid crystal display device, and as shown, the transflective liquid crystal display device is divided into a reflecting portion and a transmissive portion. It has a structure in which a process of forming a reflector is added.

In the transflective liquid crystal display device, the reflecting portion and the transmissive portion are visually recognized by turning on / off the backlight, and the cell gap of the transmissive portion generally has a value approximately twice that of the cell gap of the reflective portion.

In Fig. 1, reference numeral 1 denotes a lower substrate, 2 a gate electrode, 3 a gate insulating film, 4 a channel layer (a-Si), 5 a ohmic contact layer (n + a-Si), and 6 a Source electrode, 7 drain electrode, 8 protective film, 9 pixel electrode, 10 resin film, 11 buffer film, 12 reflective electrode, 14 upper substrate, 15 color filter layer, 16 Denotes a common electrode, 20 denotes a liquid crystal layer, dr denotes a cell gap in a reflecting portion, and dt denotes a cell gap in a transmissive portion, respectively.

However, the above-mentioned conventional transflective liquid crystal display device has to undergo a 5-mask process, that is, a gate mask process, an active mask process, an S / D mask process, a via hole mask process, and an ITO mask process to form a transmissive portion. In addition, since the two-mask process for the resin film patterning process and the reflective electrode forming process must be additionally performed to form the reflecting part, approximately seven mask processes should be performed, and the mask process is a photosensitive film coating and exposure by itself. And the development process and the etching process, the overall process is very complicated, and the mask process is further performed as compared with the manufacturing method of the transmissive and reflective liquid crystal display device in which 5 or 6 mask processes are usually performed. There is a problem that the manufacturing cost and time-consuming.

In order to implement a transflective structure in a liquid crystal display device, it is important to maintain a constant level between the reflecting part and the transmitting part. When the ITO film is formed under the resin film, that is, the organic insulating film according to the conventional method, the VT voltage of the liquid crystal display device is maintained. In the graph showing the characteristic, the slope of the curve is increased, which makes it difficult to implement gradation. In addition, there is a problem in that the level difference of the reflector must be lowered to implement the gray scale of the liquid crystal display device.

Therefore, in order to implement a high opening ratio structure in the transflective liquid crystal display device, the parasitic voltage is generated by maintaining the thickness of the organic insulating film to be greater than or equal to (3 µm or more) and by arranging the distance between the pixel electrode and the data line to be greater than or equal to or greater than a predetermined distance. It is important to suppress it. However, there is a problem that it is difficult to realize high aperture ratio characteristics of the pixel electrode with the structure in which the pixel electrode is located under the organic insulating layer.

Accordingly, an object of the present invention is to provide a semi-transmissive liquid crystal display device and a method of manufacturing the same, which have been devised to solve the above-mentioned problems and reduce manufacturing cost and time by reducing the number of mask processes. .

Another object of the present invention is to provide a transflective liquid crystal display device and a method of manufacturing the same, which have improved gray scale characteristics.

In order to achieve the above object, the present invention provides a semi-transmissive liquid crystal display device having a reflecting part including a reflecting electrode for displaying an image with ambient light and a transmissive part for displaying an image with light of a backlight. A substrate and an upper substrate; A thin film transistor formed on the lower substrate and including a gate electrode, a channel layer, an active layer, and a source / drain electrode; An organic resin film formed on the lower substrate such that thicknesses of the reflection part and the transmission part are different from each other; A transmissive electrode formed on the organic resin film to be in contact with the thin film transistor; A reflective electrode formed on the reflective portion of the lower substrate and formed on the transmission electrode; A common electrode formed on the upper substrate; And a liquid crystal layer interposed between the lower substrate and the upper substrate.

Here, the step between the reflecting portion and the transmitting portion is formed to be 1.5 μm or more.

In addition, the present invention comprises the steps of forming a gate electrode on the insulating substrate; Forming a channel layer and an active layer including a gate insulating film, an a-Si film, and an n + a-Si film on an entire surface of a lower substrate to cover the gate electrode; Depositing a source / drain metal film on the substrate resultant and then patterning the source / drain metal film to form a source / drain electrode; After forming the passivation layer on the substrate resultant, etching the passivation layer to form a via hole exposing a thorough electrode of the thin film transistor; Forming an organic resin film having a different thickness between the reflective part and the transmissive part on the substrate product including the protective film; And forming a transmission electrode and a reflection electrode on the via hole and the organic resin film.

The forming of the transmissive electrode and the reflective electrode may include forming an organic resin film on the passivation layer, and then depositing an ITO film for the pixel electrode and Al for the reflective electrode; Forming a photoresist pattern on the entire surface of the substrate; Irradiating a laser to a reflecting unit and a transmitting unit where the organic resin film is formed; Performing wet etching on the pixel electrode ITO film and the reflective electrode Al; Removing the photoresist pattern remaining on the transmission part through ashing; Removing the reflective electrode of the transmission part; And removing the photoresist pattern remaining on the substrate resultant.

The irradiating of the laser to the reflecting portion and the transmitting portion may be performed by irradiating a laser having energy of at least a portion capable of completely removing the photoresist pattern of the exposed portion to the reflecting portion and an intermediate energy of less than or equal to energy capable of completely removing the photosensitive layer pattern of the exposed portion at the transmitting portion. Irradiate a laser having.

The photosensitive film pattern is formed to have a thickness of 2 to 3 µm.

(Example)

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

2 is a cross-sectional view illustrating a transflective liquid crystal display device according to an exemplary embodiment of the present invention.

As shown in FIG. 2, in the transflective liquid crystal display according to the present invention, the gate electrode 22 is formed on the lower substrate 21, and the gate insulating film 23 is formed on the substrate product including the gate electrode 22. Is formed. On the gate insulating film 23, a channel layer 24 made of an a-Si film and an n + a-Si film and an active layer 25 are formed, respectively. In this case, the active layer 25 is formed so that the top surface of the channel layer 24 is exposed. Source / drain electrodes 26 and 27 made of a source / drain metal film are formed on the substrate resultant, and a passivation layer 28 is formed on the substrate resultant including the source / drain electrodes 26 and 27. The via layer is formed by etching the passivation layer 28 to expose the constituent elements 26 of the thin film transistor, and an organic resin layer 30 having different thicknesses between the reflective and transmissive portions is formed on the passivation layer 28. do. Transmissive electrodes 31 and reflective electrodes 32 are formed on the via holes and the organic resin layer 30. In this case, the transmission electrode 31 and the reflection electrode 32 are formed at the same time.

Hereinafter, a method of manufacturing the transflective liquid crystal display according to the present invention described above will be described with reference to FIGS. 3A to 3F.

As shown in FIG. 3A, a gate bus line (not shown) including the gate electrode 22 is formed on the lower substrate 21 made of a transparent insulating substrate such as a glass substrate using a first mask process.

As shown in FIG. 3B, a gate insulating film 23, an a-Si film, and an n + a-Si film are sequentially deposited on the entire surface of the lower substrate 21 to cover the gate electrode 22 and the gate bus line. Next, the n + a-Si film and the a-Si film are patterned using a second mask process, thereby forming the channel layer 24 and the active layer 25.

As shown in FIG. 3C, the source / drain metal layer is deposited on the substrate resultant, and then the source / drain metal layer is patterned using a third mask process to form source / drain electrodes 26 and 27. do. A protective film 28 is then formed on the substrate resulting from the source / drain electrodes 26 and 27.

As shown in FIG. 3D, in the state in which the passivation layer 28 is formed on the substrate resultant, the via layer exposing the source electrode 26 of the thin film transistor by etching the passivation layer 28 through a fourth mask process. To form.

As shown in FIG. 3E, after the organic resin is coated on the passivation layer 28, the organic resin is exposed and developed through a fifth mask process to have an organic resin layer having different thicknesses between the reflecting unit and the transmitting unit. 30). In this case, the organic resin film 30 is formed so that the step between the reflecting portion and the transmitting portion is 1.5 μm or more.

As shown in FIG. 3F, an ITO film for pixel electrodes is deposited on the via holes and the organic resin film 30, and then Al for reflective electrodes is deposited on the ITO film. Next, the ITO film and the Al are patterned using a sixth mask process to form the transmission electrode 31 and the reflection electrode 32, thereby completing the fabrication of the array substrate.

Here, in the conventional process, the pixel electrode formation, the organic resin film formation, and the reflective electrode are sequentially formed after the via hole is formed. In the present invention, the organic resin film is formed after the via hole is formed, and the pixel electrode / reflection is performed in one mask process. By simultaneously forming the electrodes, one mask process can be reduced, so that process simplification and manufacturing cost can be obtained.

Subsequently, the lower substrate 21 manufactured by the above-described process and the upper substrate 44 formed by forming only the common electrode 46 of the ITO without the color filter are formed to be bonded to each other under the interposition of the liquid crystal layer 40. This completes the transflective liquid crystal display device of the present invention.

4A to 4F are cross-sectional views of processes for describing a sixth mask process according to an embodiment of the present invention.

As shown in FIG. 4A, after forming the organic resin film 30 having different thicknesses between the reflective and transmissive portions on the passivation layer 28, an ITO film for the pixel electrode and Al for the reflective electrode are deposited. The photoresist pattern 70 is formed on the entire surface of the substrate. At this time, the photosensitive film pattern 70 is formed to have a thickness of 2 to 3㎛.

As shown in FIG. 4B, the reflective portion from which the organic resin layer 30 protrudes is irradiated with a laser having an energy E _th or more capable of completely removing the photoresist pattern of the exposed portion, and the transmissive portion is irradiated with E _th or less. It develops after irradiating the laser which has energy. At this time, since the thickness of the photosensitive film pattern 70 of the reflecting part and the transmitting part is different, even if the same amount of laser is irradiated to the reflecting part and the transmitting part, the solubility of the reflecting part and the transmitting part is changed so that the halftone type has a constant thickness on the upper part of the transmitting part. The photoresist pattern is left.

As shown in FIG. 4C, the organic resin film 30 is exposed by performing wet etching using an etching solution on the ITO film for the pixel electrode and the Al for the reflective electrode.

As shown in FIG. 4D, the reflective electrode 32 of the transmissive part is exposed by ashing the thickness of the halftone photoresist pattern remaining on the transmissive part.

As shown in FIG. 4E, the reflective electrode 32 of the transmission part is removed through selective etching to expose the transmission electrode 31 of the transmission part.

As shown in FIG. 4F, the photoresist layer pattern 70 remaining on the substrate resultant is removed so that the reflective electrode 32 having a high reflectivity in the reflecting portion and the transmitting electrode 31 remain in the transmitting portion.

In the present invention, a semi-transmissive liquid crystal display device is manufactured using a six mask process, but a gate mask process as a first mask process, an active mask process as a second mask process, an S / D mask process as a third mask process, and a fourth mask process. The ITO / reflective mask process may be performed using the via hole / resin mask process and the fifth mask process to manufacture the transflective liquid crystal display device using the five mask process.

In the above, the present invention has been described with reference to some examples, but the present invention is not limited thereto, and a person of ordinary skill in the art may make many modifications and variations without departing from the spirit of the present invention. I will understand.

As described above, in the present invention, the organic resin film is formed after the via hole is formed, and the pixel electrode / reflective electrode is simultaneously formed by one mask process, thereby simplifying the process and reducing the manufacturing cost by reducing the number of masks. Can be.

In addition, the present invention can improve the aperture ratio of the liquid crystal display by forming a transmissive electrode on the organic resin film, the organic resin film does not exist on the transmissive electrode to reduce the loss of the voltage charged in the transmissive electrode liquid crystal The gray scale characteristic of the display device can be improved. Accordingly, the characteristics and reliability of the liquid crystal display device can be improved.

Claims (6)

A semi-transmissive liquid crystal display device comprising a reflecting portion including a reflecting electrode for displaying an image with ambient light and a transmitting portion for displaying an image with light of a backlight. A lower substrate and an upper substrate disposed to face each other; A thin film transistor formed on the lower substrate and including a gate electrode, a channel layer, an active layer, and a source / drain electrode; An organic resin film formed on the lower substrate such that thicknesses of the reflection part and the transmission part are different from each other; A transmissive electrode formed on the organic resin film to be in contact with the thin film transistor; A reflective electrode formed on the reflective portion of the lower substrate and formed on the transmission electrode; A common electrode formed on the upper substrate; And And a liquid crystal layer interposed between the lower substrate and the upper substrate. The semi-transmissive liquid crystal display device according to claim 1, wherein the step between the reflecting part and the transmitting part is formed to be 1.5 µm or more. Forming a gate electrode on the insulating substrate; Forming a channel layer and an active layer including a gate insulating film, an a-Si film, and an n + a-Si film on an entire surface of a lower substrate to cover the gate electrode; Depositing a source / drain metal film on the substrate resultant and then patterning the source / drain metal film to form a source / drain electrode; After forming the passivation layer on the substrate resultant, etching the passivation layer to form a via hole exposing a thorough electrode of the thin film transistor; Forming an organic resin film having a different thickness between the reflective part and the transmissive part on the substrate product including the protective film; And And forming a transmissive electrode and a reflective electrode on the via hole and the organic resin layer. The method of claim 3, wherein the forming of the transmission electrode and the reflection electrode Forming an organic resin film on the protective film, and then depositing an ITO film for a pixel electrode and Al for a reflective electrode; Forming a photoresist pattern on the entire surface of the substrate; Irradiating a laser to a reflecting unit and a transmitting unit where the organic resin film is formed; Performing wet etching on the pixel electrode ITO film and the reflective electrode Al; Removing the photoresist pattern remaining on the transmission part through ashing; Removing the reflective electrode of the transmission part; And And removing a photoresist pattern remaining on the substrate resultant. The method of claim 4, wherein the irradiating the laser to the reflecting unit and the transmitting unit comprises: The reflecting portion is irradiated with a laser having an energy of at least energy capable of completely removing the photoresist pattern of the exposed portion, and the transmissive portion is irradiated with a laser having an intermediate energy of less than or equal to energy capable of completely removing the photoresist pattern of the exposure portion. Method of manufacturing a liquid crystal display device. The method of manufacturing a transflective liquid crystal display device according to claim 4, wherein the photosensitive film pattern is formed to have a thickness of 2 to 3 µm.

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