Color filter substrate, a method of fabricating the same, a display device including the same, and method of fabricating the display device

A color filter substrate including a base substrate, a color layer on the base substrate, a conductive layer on the color layer, and a grain compensation layer between the color layer and the conductive layer. The grain compensation layer includes zinc oxide and a metal oxide other than zinc oxide. A content of the metal oxide is lower than that of the zinc oxide in the grain compensation layer. The grain compensation layer increases the grain size of the conductive layer.

CROSS-REFERENCE TO RELATED APPLICATION

This U.S. non-provisional patent application claims priority from and the benefit of Korean Patent Application No. 10-2013-0079224, filed on Jul. 5, 2013, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND

Field

Exemplary embodiments of the present invention relate to a color filter substrate, a method of fabricating the same, a display device including the same, and a method of fabricating the display device and, more particularly, to a color filter substrate capable of preventing a border stain, a method of fabricating the same, a display device including the same, and a method of fabricating the display device.

Discussion of the Background

Display devices include organic light emitting display devices, liquid crystal display device, plasma display devices, and electrophoretic display devices. The liquid crystal display device has relatively low power consumption, excellent portability, and high value.

Generally, the liquid crystal display device includes an array substrate, a color filter substrate opposite the array substrate, and a liquid crystal layer disposed therebetween. The liquid crystal display device displays an image by application of an electric field to the liquid crystal layer.

The color filter substrate includes a color layer having red, green, and blue colors, and a common electrode layer for generating the electric field in the liquid crystal layer. Light transmitted through the color filter substrate may therefore exhibit various colors.

SUMMARY

Exemplary embodiments of the present invention provide a color filter substrate that is capable of increasing a grain size of a common electrode layer and is capable of preventing the occurrence of a border stain, and also provide a display device including the same.

Exemplary embodiments of the present invention also provide a method of fabricating the color filter substrate and a method of fabricating the display device.

An exemplary embodiment of the present invention discloses a color filter substrate including a base substrate, a color layer disposed on the base substrate, a conductive layer disposed on the color layer, and a grain compensation layer. The grain compensation layer includes zinc oxide (ZnO) and a first metal oxide different from the zinc oxide. A content of the first metal oxide is lower than that of the zinc oxide in the grain compensation layer. The grain compensation layer is disposed between the color layer and the conductive layer to increase a grain size of the conductive layer.

An exemplary embodiment of the present invention also discloses a display device including a color filter substrate, an array substrate opposing the color filter substrate and including driving elements, and a liquid crystal layer sealed between the color filter substrate and the array substrate. An electric field corresponding to each of pixels is generated in the liquid crystal layer. The color filter substrate includes a base substrate, a color layer disposed on the base substrate, an insulating layer disposed on the color layer, a conductive layer disposed on the color layer; and a grain compensation layer disposed between the insulating layer and the conductive layer. The grain compensation layer may include zinc oxide (ZnO) and a first metal oxide different from the zinc oxide. A content of the metal oxide is lower than that of the zinc oxide in the grain compensation layer, and the grain compensation layer increases a grain size of the conductive layer.

An exemplary embodiment of the present invention also discloses a method of fabricating a color filter substrate including forming a color layer on a base substrate, forming a grain compensation layer on the color layer, and forming a conductive layer on the grain compensation layer. The grain compensation layer may include zinc oxide (ZnO) and a first metal oxide different from the zinc oxide. A content of the metal oxide is lower than that of the zinc oxide in the grain compensation layer and the grain compensation layer increases a grain size of the conductive layer.

An exemplary embodiment of the present invention also discloses a method of fabricating a display device including forming driving elements on an array substrate, forming a color filter substrate, bonding the color filter substrate to the array substrate, and injecting a liquid crystal between the color filter substrate and the array substrate to form a liquid crystal layer. Forming the color filter substrate includes forming a color layer including at least one color filter and a black matrix adjacent to the at least one color filter on a base substrate, forming a grain compensation layer on the color layer, and forming a conductive layer on the grain compensation layer. The grain compensation layer includes zinc oxide (ZnO) and a first metal oxide different from the zinc oxide. A content of the metal oxide is lower than that of the zinc oxide in the grain compensation layer. The grain compensation layer increases a grain size of the conductive layer.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The invention is described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure is thorough, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of elements may be exaggerated for clarity. Like reference numerals in the drawings denote like elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular terms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

It will be understood that when an element or layer is referred to as being “on”; “connected to”; or “coupled to” another element or layer, it can be directly on; directly connected to; or directly coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element or layer is referred to as being “directly on”; “directly connected to”; or “directly coupled to” another element or layer, there are no intervening elements or layers present. It will be understood that for the purposes of this disclosure, “at least one of X, Y, and Z” can be construed as X only, Y only, Z only, or any combination of two or more items X, Y, and Z (e.g., XYZ, XYY, YZ, ZZ).

Exemplary embodiments are described with sectional views as exemplary views of the present invention. Accordingly, shapes of the exemplary views may be modified according to manufacturing techniques and/or allowable errors. Therefore, the exemplary embodiments are not limited to the specific shape illustrated in the exemplary views, but may include other shapes that may be created according to manufacturing processes. Areas exemplified in the drawings have general properties, and are used to illustrate specific shapes of elements. Thus, this should not be construed as limited to the scope of the present invention.

As illustrated inFIGS. 1 and 2, a display device DP includes a lower substrate100, a color filter substrate200, and a liquid crystal layer300. The lower substrate100may be an array substrate on which a plurality of driving elements and signal interconnections are disposed.

A plurality of pixels PX are connected to the signal interconnections disposed on the lower substrate100. The signal interconnections may include data lines DL and gate lines GL.

The data lines DL may be spaced apart from each other in a first direction DR1and to extend in a second direction DR2crossing the first direction DR1. The gate lines GL may be spaced apart from each other in the second direction DR2and extend in the first direction DR1. The data lines DL and the gate lines GL may selectively apply electrical signals to the pixels PX.

Each of the pixels PX includes at least one switching element Tr and a pixel electrode PE. Each of the pixels PX may output data according to the electrical signals. The switching element Tr may include a gate electrode, a source electrode, a drain electrode, a semiconductor active layer, and a gate insulating layer. The gate electrode is electrically connected to the gate line GL. The source electrode is electrically connected to the data line DL.

The pixel electrode PE is electrically connected to the drain electrode. The pixel electrode PE may constitute a capacitor in each of the pixels PX. The pixel electrode PE controls movement of the liquid crystals corresponding thereto, thereby controlling a transmission amount of light. The capacitor in each pixel PX may be turned-on/off independently of the capacitors of other pixels PX by the switching element Tr.

As illustrated inFIG. 2, an insulating layer IL may be disposed on the pixel electrode PE. The insulating layer IL protects the pixel electrode PE. The insulating layer IL may insulate the pixel electrode PE from the liquid crystals.

As illustrated inFIG. 1, the color filter substrate200is disposed to oppose the lower substrate100. The color filter substrate200may include a plurality of light transmitting regions DA and a light shielding region SA disposed between the light transmitting regions DA. Regions of the color filter substrate200corresponding to the pixels PX of the lower substrate100are illustrated with intersecting lines. Each of the light transmitting regions DA may overlap with each of the pixel electrodes PE. The light shielding region SA may be arranged in a lattice-shape (or a mesh-shape). The light shielding region SA may overlap with the signal interconnections and the switching elements Tr.

The color filter substrate200will be described in more detail with reference toFIG. 2. As illustrated inFIG. 2, the color filter substrate200includes a base substrate210, a color layer220, a grain compensation layer230, and a conductive layer240.The base substrate210is exposed toward the outside of the display device DP, and the conductive layer230faces the lower substrate100. Hereinafter, elements of the color filter substrate300will be described in a direction DR3from the outside to the inside of the display device DP.

One surface of the base substrate210is exposed toward the outside of the display device DP. The base substrate210covers the display device DP. The base substrate210maintains a stack structure of the color filter substrate200and protects the display device DP from the external environment. The base substrate210may be transparent so that information (e.g., an image) realized by the display device DP can be transmitted through the base substrate210to a viewer. For example, the base substrate210may include at least one of a glass, a synthetic resin, and a ceramic material. The color layer220is disposed on another surface of the base substrate210. The color layer220provides colors to light which is output from the inside of the display device DP. The color layer220includes color patterns CL and a light shielding layer BM.

As illustrated inFIGS. 1 and 2, the light shielding layer BM includes a plurality of openings. The light shielding layer BM may be a black matrix. The light shielding layer BM shields the light transmitted from the inside of the display device DP to form the light shielding region SA. The light shielding layer BM includes a material which is highly reflective. The light shielding layer BM may include a highly-reflective metal or a black resin material. For example, the light shielding layer BM may include any one of chrome, a double layer of chrome/chrome oxide, a carbon pigment, and graphite

As illustrated inFIG. 2, the color filter CL is disposed in each of the openings. Thus, the color layer220includes at least one color filter CL in each pixel. The color filter CL and the light shielding layer BM may be disposed in the same plane to form the color layer220.The color filters CL overlap with the openings, respectively. Additionally, even though not shown in the drawings, the color filters CL may respectively overlap with portions of the light shielding layer BP that are adjacent to the openings.

The color filters CL may include pigments having various colors, respectively. Colors expressed by the color filters CL are determined depending on the pigments. For example, the color filters CL may include a red color, a blue color, a green color, and a white color, respectively.

The color filters CL disposed in a plurality of openings adjacent to each other may include materials having different transmittances from each other. The various colors may be embodied depending on the transmittances. Thus, the color filters CL in the openings have different colors from each other. The color filters CL may correspond to the light transmitting regions DA. Thus, the light transmitting regions DA may express different colors from each other.

As a result, the light shielding layer BM may at least partially define the light transmitting regions DA. The light shielding layer BM prevents light leakage and color interference between colors expressed by the color filters CL, thereby improving color resolution of the display device DP.

The conductive layer240is disposed on the color layer220. The conductive layer240may be a common electrode. The conductive layer240and the pixel electrode PE of the lower substrate100may constitute a capacitor on each pixel PX. The conductive layer240may be formed of a transparent conductive material. For example, the conductive layer240may be formed of at least one of indium-tin oxide, indium-zinc oxide, indium-gallium-zinc oxide, fluorine-zinc oxide, gallium-zinc oxide, and tin oxide.

The grain compensation layer230is disposed between the color layer220and the conductive layer240. The grain compensation layer230may be formed of a transparent material having a high transmittance. Additionally, the grain compensation layer230is used as a seed layer for determining a grain size of the conductive layer240. A grain size of the conductive layer240formed on the grain compensation layer230is greater than that of the conductive layer240formed on the color layer220without the grain compensation layer230. The grain compensation layer230increases the grain size of the conductive layer240. Thus, the grain compensation layer230may be a thin poly-crystalline layer having a high light transmittance. The grain compensation layer230includes a transparent poly-crystalline material. For example, the transparent poly-crystalline material may include zinc oxide (ZnO).

The grain compensation layer230includes zinc oxide as a base material and further includes a metal oxide different from zinc oxide. Because the grain compensation layer230includes a mixture of the zinc oxide and the metal oxide, the grain size of the conductive layer240disposed on the grain compensation layer230may be easily controlled.

The grain compensation layer230may include various amounts of the metal oxide. However, in the grain compensation layer, the content of the metal oxide is less than the content of the zinc oxide. For example, the grain compensation layer230may include the metal oxide of about 1 wt % to about 30 wt %. The metal oxide may be aluminum oxide (Al2O3) or gallium oxide (Ga2O3). Alternatively, the metal oxide may include both aluminum oxide (Al2O3) and gallium oxide (Ga2O3).

The grain compensation layer230may be formed of an aluminum-zinc oxide (AZO) thin layer including aluminum oxide (Al2O3). Alternatively, the grain compensation layer230may be formed of a gallium-zinc oxide (GZO) thin layer including gallium oxide (Ga2O3). Further still, the grain compensation layer230may be formed of a poly-crystalline thin layer including both aluminum oxide (Al2O3) and gallium oxide (Ga2O3).

The grain compensation layer230may be formed to have one of various thicknesses. For example, the grain compensation layer230may have a thickness in the range of about 50 Å to about 200 Å. If the grain compensation layer230is thicker than about 200 Å, a resistance of the grain compensation layer230may be too high. Thus, it is difficult to control the capacitance between the conductive layer240and the pixel electrode PE such that a power consumption of the display device DP may be increased. If the grain compensation layer230is less than about 50 Å, it may be difficult for the grain compensation layer230to act as the seed layer.

Referring toFIGS. 1 and 2, the liquid crystal layer300is disposed between the lower substrate100and the color filter substrate200. The liquid crystal layer300may be sealed between the lower substrate100, the color filter substrate200, and a spacer (not shown) disposed between the lower substrate100and the color filter substrate200.

The liquid crystal layer300, the conductive layer240, and the pixel electrode PE constitute the capacitor. The liquid crystal layer300has various arrangements determined by the electric field generated by a voltage difference between the conductive layer240and the pixel electrode PE. The liquid crystal layer300controls the transmission amount of the light transmitted through the lower substrate100, according to the orientation of liquid crystals included therein.

The liquid crystal layer300has both fluidity and anisotropy. The liquid crystal layer300may include a twisted nematic liquid crystal, a smectic liquid crystal, a vertical alignment liquid crystal, a cholesteric liquid crystal, or a homogeneous alignment liquid crystal.

Even though not shown in the drawings, the display device DP may further include an alignment layer (not shown) disposed between the liquid crystal layer300and the color filter substrate200. Additionally, the display device DP may further include an optic member (not shown) disposed on an outer side of the base substrate210of the color filter substrate200.

FIGS. 3A to 3Care scanning electron microscope (SEM) micrographs of indium-tin oxide thin layers respectively disposed on different layers.FIG. 3Aillustrates a SEM photograph of an indium-tin oxide thin layer grown on an insulating layer.FIG. 3Billustrates a SEM photograph of an indium-tin oxide thin layer grown on a zinc oxide thin layer.FIG. 3Cillustrates a SEM photograph of an indium-tin oxide thin layer grown on the grain compensation layer230. The photographs ofFIGS. 3A to 3Care images magnified by a factor of 150,000.

InFIG. 3B, the zinc oxide thin layer does not include other metal oxides. InFIG. 3C, the grain compensation layer230includes aluminum oxide (Al2O3). InFIG. 3C, the zinc oxide thin layer including 2 wt % aluminum oxide (Al2O3) was formed on an insulating layer. The influence of the grain compensation layer230on the grain size of the conductive layer240will be described with reference toFIGS. 3A to 3C.

Referring toFIGS. 3A and 3B, a grain size of the indium-tin oxide grown on the zinc oxide thin layer was minutely greater than a grain size of the indium-tin oxide grown on the insulating layer. This is because the zinc oxide thin layer has a basically poly-crystalline structure. Alternatively, the insulating layer is formed of a polymer resin layer. Thus, the insulating layer may be amorphous.

Referring toFIGS. 3A to 3C, the grain size of the indium-tin oxide thin layer on the grain compensation layer230is the greatest. Due to the presence of the grain compensation layer230, the grain size of the conductive layer240is remarkably increased. Because the grain compensation layer230includes the metal oxide added into the zinc oxide thin layer, its seed layer function may be improved.

The zinc oxide thin layer may be generally used as a buffer layer. The grain compensation layer230has an adhesive strength similar to that of the zinc oxide thin layer. However, the influence of the grain compensation layer230on the grain size of the conductive layer240is greater than the influence of the zinc oxide thin layer on the grain size of the conductive layer240.

Generally, if a grain size of a material is increased, a number of grains in the unit area is decreased. Therefore total contact areas of the grains may be reduced. And a grain boundary may be reduced. The grain boundary between the grains may be a path through which moisture can permeate. As the grain size is increased, the path through which the moisture permeates may be reduced.

The moisture permeated into a display device may cause a stain. The stain may mainly occur in a border portion of the display device that is in contact with an external environment. Thus, the grain size of the conductive layer240is controlled to prevent the border stain from occurring.

FIG. 4is a cross-sectional view illustrating a color filter substrate according to an exemplary embodiment. In the present exemplary embodiment, the same elements as illustrated inFIGS. 1, 2, and 3A to 3Cwill be indicated by the same reference numerals or the same reference designators. The descriptions for the same elements as illustrated inFIGS. 1, 2, and 3A to 3Cwill be omitted.

The color filter substrate200may further include an insulating layer250. The insulating layer250is disposed between the color layer220and the grain compensation layer230. The insulating layer250may be, for example, an overcoat layer. The insulating layer250may protect the color layer220and may planarize a top surface of the color layer220.

The insulating layer250maybe transparent so that light outputted from the inside of the display device DP is shown to users. The insulating layer250may include polyimide, polyacrylate, polyacrylamide, polyurethane, and/or polyvinylacrylate.

The insulating layer250may planarize both the color layer220and the grain compensation layer230. Thus, because the display device DP further includes the insulating layer250, a thickness of the grain compensation layer230may be easily controlled. Additionally, the grains of the conductive layer240may be uniformly formed.

FIG. 5is a cross-sectional view illustrating a color filter substrate according another exemplary embodiment. In this exemplary embodiment, the same elements as described with reference toFIGS. 1 to 4will be indicated by the same reference numerals or the same reference designators. The descriptions for the same elements as illustrated inFIGS. 1 to 4will be omitted.

As illustrated inFIG. 5, the grain compensation layer230may include a first grain compensation layer231and a second grain compensation layer232.The first grain compensation layer231includes zinc oxide and a first metal oxide different from zinc oxide. The second grain compensation layer232includes zinc oxide and a second metal oxide different from zinc oxide.

The first metal oxide may be different from the second metal oxide. Alternatively, the grain compensation layer230may have a stack structure including a plurality of layers having the same composition.

FIGS. 6A to 6Gare cross-sectional views illustrating a method of fabricating a color filter substrate according to an exemplary embodiment. Meanwhile, the array substrate including driving elements is bonded to the color filter substrate, and then the liquid grain layer is injected into a space between the array substrate and the color filter substrate to form a display device according to an exemplary embodiment.

The driving elements and a plurality of signal interconnections providing electrical signals to the driving elements are formed on a substrate, thereby forming the array substrate. For example, the array substrate may be formed through a deposition process, an exposure process, a development process, and etching process, et cetera. Hereinafter, a method of fabricating the color filter substrate in a method of fabricating the display device will be described with reference toFIGS. 6A to 6G.

The method of fabricating the color filter substrate includes forming a color layer on a substrate, forming an overcoat layer, forming a grain compensation layer, and forming a conductive layer.

As illustrated inFIG. 6A, a light shielding material BL is coated on a substrate210. The light shielding material BL may be formed of a photosensitive resin containing a black pigment. The black pigment may be, for example, a carbon black. A mask MA is disposed on the light shielding material BL coated on the substrate210. The mask MA includes a plurality of light shielding parts BR and a plurality of transmitting parts TR. If light is irradiated to the mask MA, only the light through the transmitting parts TR reaches the light shielding material BL. A mask MA is disposed on the light shielding material BL coated on the substrate210. The mask MA includes a plurality of light shielding parts BR and a plurality of transmitting parts TR. If light is irradiated to the mask MA, only the light through the transmitting parts TR reaches the light shielding material BL.

As illustrated inFIG. 6B, the photolithography process is performed to form a light shielding layer BM having a plurality of openings BM-OP. If the light shielding material BL includes a positive photoresist, the openings BM-OP are formed at regions corresponding to the transmitting parts TR. Alternatively, if the light shielding material BL includes a negative photoresist, the plurality of openings BM-OP may be formed at regions corresponding to the light shielding parts BR even though not shown in the drawings.

As illustrated inFIG. 6C, color filters CL are formed in the openings BM-OP, thereby forming the color layer220. For example, the color filers CL having pre-selected colors may be formed in the openings BM-OP by a printing method. The color filters CL may sequentially fill the plurality of the openings BM-OP.

Even though not shown in the drawings, the color filters CL may be formed by various methods except a printing method. For example, the color filters CL may be formed using a process selected from a group consisting of a dyeing method, an electro-deposition method, and a pigment dispersion method. However, if a dyeing method or a electro-deposition method is used, the color filters CL may be formed before the light shielding layer BM is formed.

As illustrated inFIG. 6D, an insulating layer250is coated on the color layer220. The insulating layer250may protect the color layer220and may be an overcoat layer for planarizing a top surface of the color layer220.

A process of forming the grain compensation layer230is illustrated inFIGS. 6E and 6F. The grain compensation layer230may be formed using a sputtering method, but the present invention is not limited thereto. In other exemplary embodiments, the grain compensation layer230may be formed by various thin layer deposition methods.

Referring toFIG. 6E, a thin layer is deposited using a deposition source on the insulating layer250. A target used as the deposition source is a mixture of zinc oxide and a metal oxide different from zinc oxide. The target may include at least one of aluminum oxide (Al2O3) and gallium oxide (Ga2O3) as the metal oxide. The zinc oxide and the metal oxide are sintered to form the target.

In a vacuum chamber, ionized argon gases are accelerated to form particles of the target. The target particles are deposited on the insulating layer250. As illustrated inFIG. 6F, the crystal compensation layer230is formed on the insulating layer250. The grain compensation layer230may be an AZO thin layer including aluminum oxide (Al2O3) used as the metal oxide. Alternatively, the grain compensation layer230may be a GZO thin layer including gallium oxide (Ga2O3) as the metal oxide.

The conductive layer240may be formed through various deposition methods such as a physical vapor deposition method, a chemical vapor deposition method, a plasma vapor deposition method, and/or an electron beam deposition method. For example, the conductive layer240may be formed by a sputtering method using the transparent conductive material as a target.

If the conductive layer240is formed on the grain compensation layer230, the conductive layer240has a first grain size. If the conductive layer240is formed on the insulating layer250, the conductive layer240has a second grain size. The first grain size is greater than the second grain size. In other words, the grain size of the conductive layer240may be increased by the grain compensation layer230. The insulating layer250has a smoother surface characteristic than the grain compensation layer230, and this characteristic may be one of main reasons for making different grain sizes for the conductive layer240. The grain compensation layer230may control the surface characteristic of the conductive layer240.

The grain compensation layer230is the poly-crystalline thin layer and acts as the seed layer of the conductive layer240. The conductive layer240formed on the grain compensation layer230has the grain size increased by the compensation layer230.

The conductive layer240having the increased grain size may inhibit external moisture from permeating into the display device. Thus, stains on the border of the display device may be prevented.

As described above, the color filter substrate according to exemplary embodiments of the present invention includes the grain compensation layer to increase the grain size of the conductive layer. Thus, the moisture permeated into the conductive layer may be blocked. Additionally, the method of fabricating the color filter substrate provides the color filter substrate including the grain compensation layer.

Moreover, the display device according to exemplary embodiments of the present invention includes a color filter substrate in which a border stain of the display device may be prevented.