Method of manufacturing display device

A method of manufacturing a display device comprises the steps of: forming a protective film on a first surface of a first base substrate; forming a polarizer including a plurality of wire grid patterns provided on a second surface of the first base substrate facing the first surface; removing the protective film from the first surface; and forming a pixel array layer on the first surface.

CLAIM OF PRIORITY

This U.S. non-provisional patent application claims priority under 35 U.S.C. § 119 of Korean Patent Application No. 10-2015-0007291 filed on Jan. 15, 2015, the entire contents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a method of manufacturing a display device, and more particularly, to a method of manufacturing a display device employing a wire grid polarizer.

In general, metal wires arrayed spaced apart from each other selectively transmit or reflect polarized light of an electromagnetic wave. That is, when an arranging period of the metal wires is shorter than a period of a wavelength of an incident electromagnetic wave, a polarized light component parallel to the metal wires is reflected and a polarized light component vertical to the metal wires is transmitted.

A polarizer having excellent polarized light efficiency, high transmittance, and a wide viewing angle may be manufactured by using this phenomenon, and this polarizer is called a wire grid polarizer.

The wire grid polarizer is recently employed in display devices.

SUMMARY OF THE INVENTION

The present invention provides a method of manufacturing a device which may prevent a failure in a manufacturing process of a display device employing a wire grid polarizer.

Embodiments of the invention provide methods of manufacturing a display device including: forming a protective film on a first surface of a first base substrate; forming a polarizer including a plurality of wire grid patterns provided on a second surface of the first base substrate facing the first surface; removing the protective film from the first surface; and forming a pixel array layer on the first surface.

In other embodiments of the invention, methods of manufacturing a display device include: forming a protective film on a first surface of a first base substrate; forming a polarizer including a plurality of wire grid patterns provided on a second surface of the first base substrate facing the first surface; patterning the protective pattern to form a metal wire; and forming a pixel array layer on the metal wire.

DETAILED DESCRIPTION OF THE INVENTION

Various modifications and variations can be made in the invention without departing from the spirit or scope of the invention. Exemplary embodiments of the invention will be described below in more detail with reference to the accompanying drawings. It should be understood, however, that it is not intended to limit the invention to the particular form disclosed, but rather it is intended that the invention cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the claims.

In the drawings, like reference numerals refer to like elements throughout. In the drawings, the dimensions of layers and regions are exaggerated for clarity of illustration. Although terms like “first” and “second” are used to describe various components, the components are not limited to these terms. These terms are used only to differentiate one component from another one. For example, without departing from the scope of the invention, a first element could be termed a second element, and similarly a second element could be termed a first element. The terms of a singular form may include plural forms unless referred to in the contrary.

Throughout the specification, when it is said that a part “includes” or “has”, it means that the part may be further intended to designate features, integers, steps, operations, elements, components, or the combination thereof. Furthermore, it means that one or more other features, integers, steps, operations, elements, parts or combinations thereof, or the additional possibility, are not precluded. It will also be understood that, when a layer, a film, a region, or a plate is referred to as being ‘on’ another layer, film, region, or plate, it can be directly on the other layer, film, region, or plate, or intervening layers, films, regions, or plates may also be present. Furthermore, it will be understood that, when a layer, a film, a region, or a plate is referred to as being ‘under’ another layer, film, region, or plate, it can be directly under the other layer, film, region, or plate, and one or more intervening layers, films, regions, or plates may also be present.

FIG. 1is a cross-sectional view illustrating a display device according to an embodiment of the invention andFIG. 2is an equivalent circuit diagram of the pixel illustrated inFIG. 1.

Referring toFIG. 1, a display device600according to an embodiment of the invention includes a backlight unit500emitting light and a display panel300displaying an image by using the light.

The backlight unit500includes a light source (not shown) emitting light, a light guide plate510receiving the light from the light source so as to guide the light toward the display panel300, and a reflector520reflecting leaked light from the light guide plate510so that the leaked light is re-incident toward the light guide plate510.

The backlight unit500is provided adjacent to a rear surface of the display panel300, and the light guide plate510is formed in a size corresponding to the display panel300so as to emit the light toward a front surface. The reflector520is provided in a size corresponding to a bottom surface of the light guide plate510, and is formed of a material having high reflectivity so as to reflect the light leaked through the bottom surface.

The display panel300includes a first substrate350, a second substrate380facing the first substrate350, and a liquid crystal layer390interposed between the first substrate350and the second substrate380.

The first substrate350includes a first base substrate310, a pixel array layer340provided on a first surface311of the first base substrate310, and a polarizer320provided on a second surface312of the first base substrate310facing the first surface311.

The display panel300is divided into a display area DA and a non-display area NDA. The polarizer320includes a plurality of wire grid patterns provided on the second surface312corresponding to the display area DA. The polarizer320may further include a reflective pattern324provided on the second surface312corresponding to the non-display area NDA.

As for the wire grid patterns323, among the light provided from the backlight unit500, an S wave that is a polarized light component parallel to an extension direction of the wire grid patterns323is reflected by a metal property (e.g., aluminum) of the wire grid patterns323, and a P wave that is a polarized light component parallel to a direction perpendicular to the extension direction of the wire grid patterns323is recognized as an effective refractive medium to be transmitted.

The reflective pattern324is formed of a material having high reflectivity such as aluminum, thus being able to reflect the light provided from the backlight unit500. Light reflected through the reflective pattern324is reflected by the reflector520of the backlight unit500so as to be re-incident toward the display panel300. Accordingly, light use efficiency may be improved by the reflective pattern324of the polarizer320.

The reflective pattern324is formed in a size corresponding to the non-display area NDA, thus reflecting incident light toward the non-display area NDA so as to be reused. Accordingly, an amount of light that is re-incident toward the display area DA is increased by the reflective pattern324, and therefore, light use efficiency of the display device600may be improved by the reflective pattern324.

The display device600may further include a transparent protective film335formed on the polarizer320. The transparent protective film335may be formed of any one of TiOx and AlOx.

The display panel300may include a plurality of pixels, a plurality of gate lines, and a plurality of data lines. Each of the plurality of pixels includes a thin film transistor TR, a liquid crystal capacitor Clc, and a storage capacitor Cst. The storage capacitor Cst may be omitted.

FIG. 2illustrates an equivalent circuit diagram of a (i×j)-th pixel of the plurality of pixels. In the (i×j)-th pixel, the thin film transistor TR is connected to the i-th gate line GLi of the plurality of gate lines and the j-th data line of the plurality of data line DLj. Thus, the thin film transistor TR responds to a gate signal received from the i-th gate line GLi so as to output a pixel voltage corresponding to a data signal received from the j-th data line DLj.

The liquid crystal capacitor Clc is charged with a pixel voltage output from the pixel transistor TR. An arrangement of liquid crystal molecules included in the liquid crystal layer390is changed according to the charge amount charged in the liquid crystal capacitor Clc. Transmittance of incident light into the liquid crystal layer390is adjusted according to the arrangement of liquid crystal molecules.

The storage capacitor Cst is connected in parallel with the liquid crystal capacitor Clc. The storage capacitor Cst allows the arrangement of the liquid crystal molecules to be maintained for a certain period.

The pixel array layer340may include a thin film transistor TR, an interlayer insulating layer346, and a pixel electrode347which constitute each pixel. Furthermore, the pixel array layer340may include a plurality of gate lines and a plurality of data lines. The thin-film transistor TR may include a gate electrode341, a source electrode344, and a drain electrode345. Specifically, the gate electrode341is formed on the first surface311of the first base substrate310, and the gate electrode341is branched off from a corresponding gate line. The plurality of gate lines and the gate electrode341are covered by the gate insulating layer342. A semiconductor layer343is formed on the gate insulating layer342corresponding to the gate electrode341, and the source electrode344and the drain electrode345are disposed on the semiconductor layer343spaced apart at a predetermined distance from each other.

The interlayer insulating film346is formed on the gate insulating film342for covering the thin film transistor TR, and the pixel electrode347is formed on the interlayer insulating film346. A contact hole346aexposing the drain electrode345of the thin film transistor TR is formed on the interlayer insulating film346, and the pixel electrode247may be electrically connected to the drain electrode345through the contact hole346a.

The structure of the pixel array layer340illustrated inFIG. 1is presented as an embodiment of the invention, and the invention is not limited thereto.

The second substrate380includes a second base substrate360, a color filter layer371, and a black matrix372. The second base substrate360is disposed so as to face the first base substrate310, and the black matrix372is provided on the second base substrate360corresponding to the non-display area NDA. The color filter layer371includes red, green and blue color pixels, and each of the color pixels at least corresponds to the display area DA. However, each of the color pixels may overlap the black matrix372.

The second substrate380further includes an overcoat layer373and a common electrode374. The overcoat layer373is an insulating layer formed so as to reduce a step difference between the black matrix372and the color filter layer371, and the common electrode374is formed on the overcoat layer373and faces the pixel electrode347so as to form the liquid crystal capacitor Clc.

The liquid crystal layer390is provided between the first substrate350and the second substrate380. Liquid crystal molecules in the liquid crystal layer390may be arranged according to magnitude of an electric field formed between the pixel electrode347and the common electrode374.

Furthermore, a dichroic polarizer400is provided on the display panel300. The dichroic polarizer400is made in the form of a sheet so as to be able to be attached on the display panel300. A polarization axis of the dichroic polarizer400may be parallel or perpendicular to the extending direction of the wire grid patterns323of the polarizer320.

FIG. 3is a perspective view illustrating the polarizer illustrated inFIG. 1andFIG. 4is an enlarged view of portion “I” illustrated inFIG. 3.

Referring toFIGS. 3 and 4, according to one embodiment of the invention, the polarizer320includes the plurality of wire grid patterns323provided on the second surface312of the first base substrate310.

The first base substrate310may be a substrate of a material through which light is transmittable, for example, silicon. In addition, the first base substrate310may be a substrate having a rectangular shape.

Each of the wire grid patterns323is extended long in a first direction D1. The first direction D1may be a direction parallel to two sides parallel to each other of the four sides of the first base substrate310. In addition, the wire grid patterns323are arranged in parallel with each other, and spaced apart at a predetermined interval from each other in the second direction D2perpendicular to the first direction D1.

The polarizer320polarizes incident light Li through the wire grid patterns323. An S wave among the incident light Li is a polarized light component parallel to an extension direction (that is, the first direction D1) of the wire grid patterns323, and is reflected by a metal property of the wire grid patterns323. A P wave among the incident light Li is a polarized light component parallel to a direction (that is, the second direction D2) perpendicular to the extension direction of the wire grid patterns323, and is recognized as an effective refractive medium to be transmitted.

When “T” is an arrangement period of the wire grid patterns323and a wavelength of the incident light Li is shorter than an arrangement period T, reflection and transmission occurring according to a polarized light component.

FIGS. 5A to 5Kare process flow diagrams illustrating a manufacturing process of the first substrate illustrated inFIG. 1.

Referring toFIG. 5A, a protective layer330is formed on the first surface311of the first base substrate310. The protective layer330may be formed of a metal material. In one embodiment of the invention, the protective layer330may be formed of molybdenum, aluminum (Al) or an alloy thereof.

As illustrated inFIG. 5B, a metal layer313is formed on the second surface312of the first base substrate310. The metal layer313may be formed of aluminum (Al). As illustrated inFIG. 5C, photoresist patterns314are formed on the metal layer313. In one embodiment of the invention, the photoresist patterns314are provided in correspondence with the non-display area NDA, and the photoresist patterns314are not provided in the display area DA.

Referring toFIG. 5D, a space between the photoresist patterns314is filled with a copolymer layer315. Herein, the copolymer layer315may be formed at a smaller height than the height of each of the photoresist patterns314. In one embodiment of the invention, the copolymer layer315includes a first polymer and a second polymer which are distributed in unspecified directions. The first and second polymers may be poly methylmethacrylate (PMMA) and poly styrene (PS), respectively.

When heat-treated, the copolymer layer315is phase separated into the first and second polymers316and317, respectively, as illustrated inFIG. 5E. In particular, the first and second polymers316and317, respectively, may be alternately arranged between two photoresist patterns314.

Then, when any one of the first and second polymers316and317is removed, the remaining one type polymers are spaced apart from each other between the two photoresist patterns314to form a nano-grid pattern318as illustrated inFIG. 5F. In one embodiment of the invention, the first polymer316formed of PMMA is removed and the second polymer317may be left to form the nano-grid pattern318.

Thereafter, the metal layer313is etched by using the nano-grid pattern318and the photoresist patterns314as masks. Then, the wire grid patterns323and the reflective pattern324are formed on the second surface312as illustrated onFIG. 5G.

Referring toFIG. 5H, the photoresist pattern314and the nano-grid pattern318which remain on upper surfaces of the wire grid patterns323and the reflective pattern324may be removed through a strip process. Thus, the polarizer320is formed on the second surface312of the first base substrate310.

Referring toFIG. 5I, a transparent protective film335may be further formed on the polarizer320. The transparent protective film335may be formed of any one of TiOx and AlOx. The transparent protective film335may protect the polarizer320from a subsequent process.

As illustrated onFIG. 5J, the protective film330on the first surface311of the first base substrate310is removed through an etching process. The protective film330is formed to prevent a failure in which a foreign substance is adsorbed on the first surface311or a scratch occurs on the first surface311in a process of forming the polarizer320on the second surface312of the first base substrate310. The protective film330may be formed on the first surface311in advance before a process of forming the polarizer320on the second surface312starts, and the protective film330may be removed from the first surface311through the etching process after the process of forming the polarizer320is completed.

Thereafter, when the protective film330is removed, a process for forming a pixel array layer340on the first surface311of the first base substrate310is performed as illustratedFIG. 5K. Detailed description of the specific process steps of the pixel array layer340will be omitted.

FIGS. 6A to 6Bare process flow diagrams illustrating a manufacturing process of a display device according to another embodiment of the invention. However, since a process of forming the polarizer320on the second surface312of the first base substrate310is the same as illustrated inFIGS. 5A to 5I, a description of the process of forming the polarizer320will be omitted to avoid repetition.

Referring toFIG. 6A, when the step of forming the polarizer320on the second surface312of the first base substrate310is completed, the protective film330(seeFIG. 5I) formed on the first surface311of the first base substrate310is patterned. The protective film330may be formed of a metal material such as aluminum, molybdenum, or an alloy thereof. Gate lines GLi and GLi+1 and gate electrodes341may be formed on the first surface311by patterning the protective film330.

In consideration of a wire resistance, when it is intended to form the gate lines GLi and GLi+1 and the gate electrode341in a double layer or triple layer, the protective film330may be formed in a double layer or triple layer in the step of forming the protective layer330.

When the gate lines GLi and GLi+1 and the gate electrodes341are formed by patterning the protective film330, the step (that is, illustrated in theFIG. 5J) of completely etching the protective layer330may be omitted. Furthermore, a step of depositing a metal layer for forming the gate lines GLi and GLi+1 and gate electrodes341may be omitted in the process of forming the pixel array layer340.

Even when a scratch or foreign substance absorption on the protective film330occurs in the process of forming the polarizer320, most of the scratch or foreign absorption substances are removed through the patterning process, and also when the protective film330is formed in a double layer or a triple layer, the scratch or the like occurring on the gate lined GLi and GLi+1 does not result in a failure.

According to embodiments of the invention, a protective film is formed on the first surface before a process of forming a polarizer on the second surface of the first base substrate starts, thus preventing a failure in which a foreign substance is absorbed on the first surface or a scratch occurs on the first surface in a process of manufacturing the polarizer.

Therefore, failure occurrence in a process of forming a pixel array layer on the first surface may be prevented.