KR20030058759A - Structure and its fabrication method of reflective layer for reflective type liquid crystal display - Google Patents

Abstract

PURPOSE: A reflective film structure of a reflective liquid crystal display and a method for manufacturing the same are provided to improve the reflective efficiency by irregularly forming metal layers at an area where a reflective film is formed, on a gate insulating film, and reduce the number of manufacturing processes, thereby improving the productivity. CONSTITUTION: A first metal uneven layer(44) is randomly formed on a substrate(11a). A gate insulating film(24) is formed on the first metal uneven layer. A second metal uneven layer(41) and an active uneven layer(45) are formed on the gate insulating film. An insulating film(42) is accumulated all over the substrate. A reflective film is formed on the insulating film. An organic insulating film(43) and a pixel electrode(14) are formed on the reflective film sequentially. The first metal uneven layer and the second metal uneven layer are formed to make embossment on the reflective film.

Description

STRUCTURE AND ITS FABRICATION METHOD OF REFLECTIVE LAYER FOR REFLECTIVE TYPE LIQUID CRYSTAL DISPLAY}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective liquid crystal display device, and more particularly, to a structure of a reflective film for improving the reflectance of a reflective film constituting the reflective liquid crystal display device and reducing the number of manufacturing steps.

The liquid crystal display device is used in various fields such as an electronic notebook, a portable information terminal, a game device, a mobile phone, etc. in addition to a notebook type word processor, a notebook personal computer, and the like. In particular, in the case of portable communication devices, a low power consumption type display is required to carry a portable device for a long time.

In the case of a transmissive liquid crystal display device in which a light source unit including a back light is separately provided, the backlight occupies 80% or more of the power consumption, so that a reflection without using the backlight is not necessary to make a low power consumption liquid crystal display device. Type liquid crystal display elements are required. In the case of the reflective liquid crystal display device, since the image must be expressed using only external light, maximizing the light efficiency is the maximum research point of the reflective liquid crystal display device. Therefore, many studies have been conducted to improve the light efficiency.

As shown in FIG. 1, a general reflective liquid crystal display device includes a thin film transistor array substrate 11 and a C / F (color filter) substrate 12 disposed to face each other. ) And the liquid crystal layer 15 formed by injecting the liquid crystal 15a between the C / F substrate 12.

The thin film transistor substrate 11 is disposed for each pixel on the lower substrate 11a and serves as a switching transistor for applying and blocking a signal voltage to the liquid crystal and the organic insulating layer 13 on the thin film transistor. And a pixel electrode 20 that applies a signal voltage applied through the thin film transistor 19 to the liquid crystal cell.

The organic insulating layer 13 includes a contact hole for exposing a predetermined portion of the thin film transistor 19, and a portion of the drain electrode of the thin film transistor 19 exposed through the contact hole is connected to the pixel electrode 20.

The reflective liquid crystal display requires a reflective film for reflecting light incident from the outside, and the pixel electrode 20 serves as a reflective film. Therefore, the pixel electrode 20 mainly uses a metal film made of aluminum or an aluminum alloy (AlNd; Aluminum-Neodymium) having excellent interface reflection characteristics. The uneven structure is formed in order to improve the reflective characteristics of the metal film. The uneven structure is due to the structure of the organic insulating layer 13 formed at the bottom thereof.

That is, by forming the organic insulating film 13 itself in an uneven structure, the pixel electrode 20 formed thereon is also formed in an uneven structure.

On the other hand, on the upper substrate 12a of the C / F substrate 12 facing the thin film transistor 11 substrate, a black matrix 18 formed at a portion corresponding to the thin film transistor 19 and a black matrix The color filter 17 which consists of color pixels arrange | positioned at the side of 18 is formed. The common electrode 16 made of indium tin oxide (ITO) is provided on the color filter 17.

As shown in FIG. 2, the thin film transistor 19 is formed on the lower substrate 11a and has a gate electrode 23 to which a scan signal is applied, and an active layer 25 provided to transmit a data signal in response to the scan signal. ), A gate insulating film 24 that electrically isolates the active layer 25 and the gate electrode 23, a source electrode 26 formed on the active layer 25 to apply a data signal, and data A drain electrode 27 for applying a signal to the pixel electrode, and a protective film 28 for protecting the source electrode 26 and the drain electrode 27. A contact hole 29 is formed in the passivation layer 28 so as to be connected to the drain electrode 27 and the pixel electrode 20 made of an opaque metal. The active layer 25 is composed of a semiconductor layer 25b formed by depositing amorphous silicon (a-Si) and an ohmic contact layer 25a doped with n + on both sides of the semiconductor layer 25b. have.

In the liquid crystal display device configured as described above, when a scan signal having a high level is applied to the gate electrode 23, a channel through which electrons can move is formed in the semiconductor layer 25b, so that a source electrode ( The data signal of 26 is transmitted to the drain electrode 27 via the semiconductor layer 25b. On the other hand, when a scan signal having a low level is applied to the gate electrode 23, the channel formed in the semiconductor layer 25b is blocked, so that the transmission of the data signal to the drain electrode 27 is stopped.

Here, in order to improve the reflection efficiency of the reflective film reflecting the incident light entering through the opaque pixel electrode 20, a photoresist layer is formed on the surface of the organic insulating film, and then embossing is formed to form an opaque film that is subsequently formed. As the concave-convex structure is formed on the surface of the pixel electrode 20, the incident light may be reflected more toward the viewer, thereby improving light efficiency.

Hereinafter, with reference to the drawings will be described a conventional reflective film structure and manufacturing method for improving the reflection efficiency.

A conventional reflective film fabrication process for forming embossing on the reflective film will be described with reference to FIGS. 3A to 3E.

First, as shown in FIG. 3A, a spin coating or roll coating method is performed on an organic insulating layer 13 made of BCB or photo acryl to form a pattern of the organic insulating layer. It is applied and the photoresist film 31 of a polymer resin is formed.

As shown in FIG. 3B, the photoresist layer 31 is blocked with a mask 32 on which non-transmissive regions A to D are selectively formed, and then ultraviolet rays (arrows on the drawing) are irradiated. do.

As shown in FIG. 3C, the result of the irradiation of the ultraviolet rays is developed to form a pattern of the photoresist selectively remaining on the organic insulating layer 13, and then a pattern of the organic insulating layer is formed through an etching process. Remove the photoresist.

As shown in FIG. 3D, the resultant is melted between the patterning and the patterning of the protective melting organic insulating film at a temperature of about 300 ° C., thereby naturally creating an embossing wave.

As shown in FIG. 3E, a metal film made of aluminum or an aluminum alloy is deposited on the organic insulating film on which the embossing is formed to form the reflective film 20.

Next, a structure and a manufacturing process of another reflective film for improving the reflectance of the reflective film on which the embossing is formed will be described in detail with reference to FIGS. 4A to 4E.

First, as shown in FIG. 4A, in order to form a pattern of an organic insulating film, a spin coating or roll coating method on an organic insulating film 13 made of BCB or photo acryl. Is applied to form a photoresist film 31 of polymer resin.

As shown in FIG. 4B, the photoresist film 31 is blocked with a diffraction mask 32 in which a non-transmissive region for light is selectively formed, and then ultraviolet rays (arrows on the drawing) are irradiated.

As shown in FIG. 4C, the result of irradiating the ultraviolet light is developed to form a pattern of the photoresist 31 having a different thickness on the organic insulating layer 13.

As shown in FIG. 4D, a pattern of an organic insulating layer is formed through an etching process and photoresist is removed.

The pattern of the organic insulating film thus formed naturally creates an embossing wave without heat treatment.

As shown in FIG. 4E, an aluminum film or an aluminum alloy is deposited on the organic insulating film on which the embossing is formed to form the reflective film 20.

By using the above conventional technology, the light efficiency can be increased by efficiently reflecting external light.

However, when the embossing is formed on the organic insulating layer to form the reflective film as the above-described convex structure as described above, a separate mask must be used for the embossing patterning, and accordingly, additional processes such as photoresist coating, develop, etching, strip, etc. This is necessary. Therefore, there is a problem that not only the process is complicated but also the manufacturing cost increases. Moreover, diffraction masks used to improve reflectance have been difficult to manufacture and costly.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a reflective film structure of a liquid crystal display device which can simplify the process and reduce manufacturing costs by forming a reflective film having an uneven structure without a separate mast process.

Another object of the present invention is to provide a method of manufacturing a reflective film having an uneven structure with improved reflectivity by a simple process.

Other objects and features of the present invention will be described in detail in the configuration and claims of the following invention.

1 is a view of a typical reflective liquid crystal display device.

2 is a detailed view of a TFT substrate constituting a general reflective liquid crystal display element.

3A-3E are flow charts of a conventional reflective film process for forming embossing on the reflective film.

4A-4E are another conventional reflective film process flow chart for improving reflectance.

FIG. 5A is a cross-sectional view illustrating a structure of a lower substrate of a reflective liquid crystal display device according to the present invention, and FIG. 5B is a view illustrating only a reflector region in FIG. 5A.

6 is a plan view showing the distribution of the uneven layer.

7A to 7E are process flowcharts of the reflective liquid crystal display TFT array substrate of the present invention having the structure as shown in FIG. 5A.

*** Explanation of symbols for main parts of drawing ***

15: liquid crystal layer 15a: liquid crystal

17: color filter 18: black matrix

19: thin film transistor 20: reflective film

23: gate electrode 24: gate insulating film

26 source electrode 27 drain electrode

29: contact hole 28: protective shield

31: photoresist 32: mask

41: third metal uneven layer 42: insulating film

43: organic insulating film 44: first metal uneven layer

45: active uneven layer

In order to achieve the above object, the present invention randomly pattern the metal uneven layer on the region where the reflective film is to be formed later, for embossing the reflective film when forming the gate electrode or the source / drain electrode or the active layer. Embossing is naturally performed on the reflective film formed on the film.

That is, in manufacturing an embossed reflective film, a structure and a manufacturing method of a reflective liquid crystal display device having excellent reflection efficiency and simple manufacturing process without providing a reflective film on a organic insulating film through a mask process as in the prior art are provided.

Structural features of the reflective liquid crystal display device reflective film of the present invention are a substrate, a metal uneven layer of the gate electrode irregularly formed on the substrate, a gate insulating film formed on the entire surface of the metal uneven layer of the gate electrode, the metal of the gate electrode on the gate insulating film An active concave-convex layer formed at the same position as the concave-convex layer, a metal concave-convex layer and a reflective film of the source / drain electrode formed at the same position as the active concave-convex layer, and an insulating film formed between the metal concave-convex layer and the reflective film of the source / drain electrode; The reflective film is embossed with a metal uneven layer and an active uneven layer of a gate electrode and a source / drain electrode.

Or a substrate, a gate insulating film on the substrate, a metal uneven layer of source / drain electrodes randomly distributed on the gate insulating film, an insulating film formed on the entire surface of the metal uneven layer, and a reflective film formed on the insulating film. In the reflective film, the embossing is formed by the metal uneven layer of the source / drain electrodes.

Or a substrate, a metal uneven layer of the gate electrode irregularly distributed on the substrate, a gate insulating film formed on the entire surface of the metal uneven layer, and a reflective film formed on the gate insulating film. Embossing is formed following the layer.

Alternatively, the embossing of the reflective film may be made of only an active uneven layer, or may be formed of a gate electrode and an active uneven layer, or an uneven layer of the gate and source / drain electrodes, or an active and source / drain uneven layer.

A method of manufacturing a reflective liquid crystal display reflective film according to the present invention is characterized by forming a metal uneven layer of the gate electrode on the gate electrode and the pixel region of the thin film transistor on the substrate, and on the metal uneven layer of the gate electrode and the gate electrode Forming a gate insulating film on the entire surface of the thin film transistor, forming an active concave-convex layer at the same position as the metal concave-convex layer of the source / drain electrodes in the active layer and the pixel region of the thin film transistor, After the entire deposition, the photoresist is formed on the source / drain electrodes and the pixel region of the thin film transistor at the same position as the active concave-convex layer on the source / drain electrode, and then the insulating film is entirely deposited and the reflective film is formed in the pixel region. And source / drain electrodes and the reflective film of the thin film transistor. It is made of a method comprising: sequentially depositing an organic insulating layer and the pixel electrode.

Or forming a metal uneven layer of a source / drain electrode in the pixel region on the gate insulating film formed on the substrate, forming an insulating film and a reflective film on the metal uneven layer of the source / drain electrode, and forming an organic insulating film on the reflective film. And the pixel electrode are sequentially deposited.

In the method of forming an embossing on the reflective film, a method of forming only one uneven layer of the gate uneven layer, the source / drain uneven layer and the active uneven layer, or forming at least two uneven layers among the uneven layers It is possible.

The structure and manufacturing method of the reflective liquid crystal display device reflective film of the present invention having the above characteristics will be described with reference to the drawings.

First, in the present invention, the process of all thin film transistors is the same as in the related art, but the conventional method used for forming a gate electrode, a data line, a thin film transistor (source / drain electrode, gate electrode, active layer) or a pad is used. Alternatively, in the present invention, the metal layer or the active layer is used for the purpose of forming an embossed pattern in the in-pixel reflecting portion in addition to the elements described above.

That is, the metal uneven layer or the active uneven layer in the pixel region is randomly patterned, and then an insulating film is deposited thereon, and then a reflective film is deposited to form a reflective film having an uneven structure, and then BCB or By stacking an organic insulating layer such as photoacryl and depositing a pixel electrode, a reflective liquid crystal display device having a high reflectance can be manufactured without an additional process according to a photo mask operation for forming embossing.

5A illustrates a liquid crystal display device according to the present invention, and FIG. 5B is a cross-sectional view of a pixel area including a reflector.

In the liquid crystal display device shown in FIG. 5A, the thin film transistors 19 of the upper substrate 12 and the lower substrate 11 including the color filters 18 have the same structure as in the prior art, but the reflection formed in the pixel region. The negative structure is a new structure, and the structure of the reflector is illustrated in detail in FIG. 5B.

Therefore, in the following description, a detailed description of the process of the thin film transistor is omitted, and mainly the structure and manufacturing method of the reflector in the pixel region will be described.

In the pixel region including the reflective film of the present invention, a first metal uneven layer 44 formed randomly on the substrate 11a, a gate insulating film 24 formed on the first metal uneven layer 44, and a gate The second metal uneven layer 41 and the active uneven layer 45 formed at the same position as the first metal uneven layer 44 on the insulating film 24, the reflective film 43, and the insulating film stacked over the entire substrate ( 42, a reflective film 43 formed on the insulating film 42, and an organic insulating film 13 made of BCB or photoacryl and a pixel electrode 14 made of a transparent ITO material are sequentially formed on the reflective film 43. It is.

The first metal layer and the second metal layer are separate metal layers isolated from the outside, and may be formed of any metal, but for the convenience of factory, the first metal layer and the second metal layer may be formed when forming the gate electrode and the source / drain electrode of the thin film transistor, respectively. It is preferable that it consists of the same metal as the said substance. In addition, the active concave-convex layer 45 may also be made of the same material as the active layer when the active layer of the thin film transistor is formed.

The first metal uneven layer 44 and the second metal uneven layer 41 are formed to form embossing on the reflective film 43 formed on the insulating film 42, and the thickness of the embossing formed on the reflective film is about 4000 to about 4,000. 8000.

The thickness of the embossing does not limit the thickness of the first metal uneven layer, the second metal uneven layer and the active uneven layer. This thickness means the thickness of the total embossing formed by the first metal uneven layer, the second metal uneven layer, and the active uneven layer, and the thickness of each uneven layer may only satisfy about 4000 to 8000 kPa. The thickness of each layer may be any thickness. Based on this aspect, the first metal uneven layer, the second metal uneven layer and the active uneven layer may be formed alone or as two or more layers as long as the thickness can be satisfied.

The embossing is formed to efficiently reflect light from the outside, and the embossing layers (44/45/41) in addition to the first metal / active / second metal uneven layers 44/45/41 are provided. 41) or one or more than two uneven layers.

Fig. 6 is a plan view showing the pixel on which the uneven layer 44/45/41 is formed.

The uneven layer may be regularly distributed in the pixel, but irregular distribution in the pixel area as shown in 6 is preferable in that light can be efficiently reflected.

Hereinafter, a method of manufacturing the thin film transistor and the reflector of the reflective liquid crystal display device according to the present invention having the structure as shown in FIG. 5A will be described in detail with reference to FIGS. 7A to 7E.

First, as shown in FIG. 7A, a metal material is sputtered on the thin film transistor substrate 11a and patterned by a photo-etching method using a photoresist to form a gate electrode of the thin film transistor. A metal uneven layer 44 of the gate electrode is formed in the region 23 and the pixel region.

At this time, the thickness of the gate electrode 23 and the metal unevenness 44 is about 2500 kPa.

As shown in FIG. 7B, an insulating material is entirely deposited on the lower substrate 11a on which the gate electrode 23 and the metal uneven layer 44 of the gate electrode are formed to form a gate insulating film 24. As the material of the gate insulating film 24, an inorganic material such as SiNx or SiO2 is used. Subsequently, the semiconductor layer 25b made of amorphous silicon (Si) and the ohmic contact layer 25a made of n + amorphous silicon doped with phosphorus (P) are successively deposited on the gate insulating film 24, and then patterned. The active concave-convex layer 45 is formed at the same position as the metal concave-convex layer 44 of the gate electrode in the active layer 25 and the pixel region of the thin film transistor.

The thickness of the active uneven layer 45 formed on the insulating film 42 is about 2000 GPa.

Next, as shown in FIG. 7C, a metal material is entirely deposited on the ohmic contact layer 25a and the gate insulating layer 24, and then patterned. The patterned metal material layer becomes a source electrode 26 and a drain electrode 27 of the thin film transistor and a metal uneven layer 41 of the source / drain electrode. The metal uneven layer 41 is formed at the same position as the metal uneven layer 44 and the active uneven layer 45 of the gate electrode and has a thickness of about 1500 kPa.

Thereafter, the ohmic contact layer 25 exposed on the source electrode 26 and the drain electrode 27 is removed by an etching operation, and the source and drain electrodes 26 and 27 including the exposed semiconductor layer 25b. ) And an inorganic material such as SiNx or SiO2 are deposited on the gate insulating film 24 on which the metal uneven layers 44 and 41 and the active uneven layer 45 are formed to form an insulating film 42. The insulating film 42 serves to electrically insulate the reflective film to be formed later from the metal uneven layer 41. Next, a reflective film 43 is deposited in the pixel region.

As shown in FIG. 7D, a passivation layer 13 made of an organic material, such as BCB or photoacryl, is formed on the entire surface of the passivation layer 13 on the drain electrode 27 of the thin film transistor. It removes by the etching operation using a mask pattern, and the contact hole 29 is formed.

As the material of the reflective film 43, a metal material having high reflectance such as aluminum (Al) or aluminum alloy (AlNd; Aluminum-Neodymium) is used.

Finally, as shown in FIG. 7E, the ITO material is deposited on the protective film 13 by sputtering and then patterned to form the pixel electrode 14. The pixel electrode 14 is connected to the drain electrode 27 of the thin film transistor through the contact hole 29.

In addition, one or two or more uneven layers of the metal uneven layer 44, the source / drain electrode uneven layer 41, and the active uneven layer 45 of the gate electrode may be formed by forming an embossing on the reflective film. It is also possible to form.

The reflective film of the reflective liquid crystal display device manufactured as described above can not only secure high reflectance due to the appropriate height and distribution of the uneven layer, but also eliminate the conventional organic insulating film patterning forming process for embossing the organic insulating film. Without applying a diffraction mask, the irregularities of the reflective film distributed randomly in the pixel can be formed to improve the reflectance, thereby reducing the production cost of the product.

The reflective liquid crystal display device of the present invention can be applied to both the liquid crystal display device of the organic insulating film structure or the liquid crystal display device of the inorganic insulating film structure, in the above-described detailed description, the first metal uneven layer, the active uneven layer and the second metal unevenness Although the structure in which all the layers are formed has been described as an embodiment, a structure having only one or two uneven layers is also possible if only the thickness (about 4000 to 8000 Pa) of the embossing formed on the reflective film can be satisfied. In addition, although the thickness of each uneven | corrugated layer is illustrated in the detailed description, depending on the number of uneven | corrugated layers, the thickness can change within the range which satisfy | fills the thickness (about 4000-8000 Pa) of embossing.

In addition, the concave-convex layer structure and the formation method of the present invention can be applied not only to the reflective liquid crystal display element but also to the reflective transmissive liquid crystal display element.

As described above, according to the present invention, when forming a source / drain gate electrode of a thin film transistor in forming a reflective film having a high reflectance, the reflection efficiency is improved by irregularly forming a patterned metal uneven layer in a region where a reflective film on the gate insulating film is to be formed. In addition, the number of manufacturing processes can be reduced, thereby contributing to the improvement of productivity.

Claims (23)

A substrate; A thin film transistor comprising a gate electrode, a source / drain electrode, and an active layer on the substrate; An uneven layer in the pixel; A reflection film on the uneven layer; An insulating film formed over the reflective film; And a pixel electrode formed over the insulating film, wherein the reflecting film is formed with an embossing layer by an uneven layer. The thin film transistor according to claim 1, wherein the uneven layer in the pixel comprises: a first metal uneven layer formed together when the gate electrode of the thin film transistor is formed; an active uneven layer formed together when the active layer of the thin film transistor is formed; A liquid crystal display device comprising a second metal concave-convex layer formed together when forming a drain electrode. The liquid crystal display device according to claim 2, wherein a gate insulating film is formed between the first metal uneven layer and the active uneven layer. The liquid crystal display device according to claim 1 or 2, wherein a protective film is formed between the second metal uneven layer and the reflective film. The reflective liquid crystal display device of claim 4, wherein the protective layer is an organic material such as BCB or acrylic. The liquid crystal display device according to claim 1, wherein the uneven layer is formed of a first uneven layer formed together when the gate electrode of the thin film transistor is formed. The liquid crystal display device of claim 1, wherein the uneven layer is formed of an active uneven layer formed together when the active layer of the thin film transistor is formed. The liquid crystal display device according to claim 1, wherein the uneven layer is formed of a second uneven layer formed together when forming the source / drain electrodes of the thin film transistor. The liquid crystal display device according to claim 1, wherein the uneven layer comprises a first uneven layer formed when the gate electrode of the thin film transistor is formed and an uneven layer formed when the active layer of the thin film transistor is formed. The liquid crystal of claim 1, wherein the uneven layer comprises a first uneven layer formed when forming a gate electrode of the thin film transistor and a second uneven layer formed when forming a source / drain electrode of the thin film transistor. Display elements. The liquid crystal display of claim 1, wherein the uneven layer comprises an active uneven layer formed when the active layer of the thin film transistor is formed and a second metal uneven layer formed when the source / drain electrode of the thin film transistor is formed. . The reflective liquid crystal display of claim 1, wherein the pattern of the metal uneven layer has an irregular size. The reflective liquid crystal display device according to claim 1, wherein the pattern of the metal uneven layer is formed at an irregular position. The reflective liquid crystal display device according to claim 1, wherein the thickness of the embossing formed on the reflective film is about 4000 to 8000 Pa. The reflective liquid crystal display of claim 1, wherein the reflective film is a metal material having a high reflectance such as aluminum (Al) or aluminum alloy (AlNd). Preparing a substrate; Forming a thin film transistor and an uneven layer on the substrate; Forming an insulating film over the thin film transistor and the uneven layer; And forming a pixel electrode by patterning the insulating layer on the insulating film. 17. The method of claim 16, wherein the thin film transistor comprises: forming a gate electrode and a gate insulating film; Forming an active layer including a channel layer and an ohmic layer; Forming a source electrode and a drain electrode; Forming a protective film and a reflective film; And forming an insulating film and a pixel electrode on the reflective film. 17. The method of claim 16, wherein the uneven layer is a first metal uneven layer made together when forming the gate electrode of the thin film transistor, an active uneven layer made together when forming the active layer, and a second made together when forming the source / drain electrode It consists of a metal uneven | corrugated layer, The manufacturing method of the liquid crystal display element characterized by the above-mentioned. The method of claim 16, wherein the uneven layer comprises a first metal uneven layer formed together when the gate electrode of the thin film transistor is formed, and an active uneven layer formed together when the active layer is formed. 17. The method of claim 16, wherein the uneven layer is formed of an active uneven layer formed together when forming an active layer and a second metal uneven layer formed together when forming a source / drain electrode. The liquid crystal display device of claim 16, wherein the uneven layer comprises a first uneven layer formed together when forming the gate electrode of the thin film transistor and a second uneven layer formed together when forming the source / drain electrode. Method of preparation. The method of claim 16, wherein the protective layer is formed of an organic material such as BCB or photoacrylic. The method of manufacturing a reflective liquid crystal display device according to claim 16, wherein the reflective film is made of a metal material having a high reflectance such as aluminum (Al) or aluminum alloy (AlNd).