Patent ID: 12232352

DETAILED DESCRIPTION

Reference will now be made in more detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to explain aspects of embodiments of the present description. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Throughout the disclosure, the expression “at least one of a, b or c” indicates only a, only b, only c, both a and b, both a and c, both b and c, all of a, b, and c, or variations thereof.

Because the disclosure may have diverse modified embodiments, particular embodiments are illustrated in the drawings and are described in the detailed description. An effect and a characteristic of the disclosure, and a method of accomplishing these will be apparent when referring to embodiments described with reference to the drawings. The subject matter of this disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

One or more embodiments of the disclosure will be described below in more detail with reference to the accompanying drawings. Those components that are the same or are in correspondence with each other are identified with the same reference numeral regardless of the figure number, and redundant explanations are not repeated unnecessarily.

It will be understood that although the terms “first,” “second,” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another.

An expression used in the singular encompasses the expression of the plural, unless it has a clearly different meaning in the context.

It will be further understood that the terms “comprises” and/or “comprising,” as used herein, specify the presence of stated features or elements, but do not preclude the presence or addition of one or more other features or elements.

It will be understood that when a layer, region, or element is referred to as being “formed on” another layer, area, or element, it can be directly or indirectly formed on the other layer, region, or element. For example, intervening layers, regions, or elements may be present.

Sizes of elements in the drawings may be exaggerated for convenience of explanation. In other words, because sizes and thicknesses of components in the drawings may be arbitrarily illustrated for convenience of explanation, the following embodiments are not limited thereto.

When a certain embodiment may be implemented differently, a specific process order may be performed differently from the described order. For example, two consecutively described processes may be performed substantially at the same time or performed in an order opposite to the described order.

In the following embodiments, it will be understood that when a layer, region, or element is referred to as being “connected to” or “coupled to” another layer, region, or element, it may be directly or indirectly connected or coupled to the other layer, region, or element. For example, intervening layers, regions, or elements may be present. In the following embodiments, it will be understood that when a layer, region, or element is referred to as being “electrically connected to” or “electrically coupled to” another layer, region, and element, it may be directly or indirectly electrically connected or coupled to the other layer, region, or element. For example, intervening layers, regions, or elements may be present.

A display device displays an image and may include a game console, a multimedia device, or a portable mobile device such as an ultra-small personal computer (PC). A display device may include a liquid crystal display, an electrophoretic display, an organic light-emitting display, an inorganic light-emitting display, a field emission display, a surface-conduction electron-emitter display, a quantum dot display, a plasma display, a cathode ray display, and/or the like. Hereinafter, an organic light-emitting display device is described as an example of a display device according to an embodiment, but the various other types of display devices described above may be used in embodiments.

FIG.1is a schematic plan view of a display device1according to an embodiment.FIG.2is a schematic cross-sectional view of a display device according to an embodiment.

Referring toFIG.1, the display device1may include a display area DA in which an image is displayed and a non-display area NDA in which no image is implemented. The display device1may provide images by using light emitted from a plurality of pixels PX in the display area DA. In an embodiment, each of the pixels PX may emit light by using a display element, for example, an organic light-emitting diode. In an embodiment, each of the pixels PX may emit red light, green light, or blue light. In an embodiment, each of the pixels PX may emit red light, green light, blue light, or white light.

Referring toFIG.2, the display device may include a substrate100, a pixel circuit layer PCL, a display element layer DEL, and a thin-film encapsulation layer TFE.

The substrate100may include glass and/or a polymer resin, such as polyethersulfone, polyacrylate, polyetherimide, polyethylene naphthalate, polyethylene terephthalate, polyphenylene sulfide, polyimide, polycarbonate, cellulose triacetate, and/or cellulose acetate propionate. The substrate100including the polymer resin may be flexible, rollable, and/or bendable. The substrate100may have a multilayer structure including a base layer including the above-described polymer resin and a barrier layer.

The pixel circuit layer PCL may be on the substrate100. The display element layer DEL may include display elements, for example, organic light-emitting diodes. The pixel circuit layer PCL may include pixel circuits and insulating layers coupled to the organic light-emitting diodes. The pixel circuit layer PCL may include a plurality of thin-film transistors, storage capacitors, and insulating layers therebetween.

A barrier layer may be further included between the pixel circuit layer PCL and the substrate100. The barrier layer prevents or reduces penetration of external foreign matter and may include a single layer or multiple layers including an inorganic material such as silicon nitride (SiNx) and/or silicon oxide (SiOx).

The thin-film encapsulation layer TFE may be on the display element layer DEL. The thin-film encapsulation layer TFE may be on the display element and cover the display element. The thin-film encapsulation layer TFE may include at least one inorganic layer and at least one organic layer. The at least one inorganic layer may include at least one inorganic material selected from aluminum oxide (Al2O3), titanium oxide (TiO2), tantalum oxide (Ta2O5), zinc oxide (ZnO), silicon oxide (SiO2), silicon nitride (SiNx), and silicon oxynitride (SiON). The at least one organic layer may include a polymer-based material. Examples of the polymer-based material may include an acrylic resin, an epoxy resin, polyimide, and/or polyethylene. In an embodiment, the at least one organic layer may include acrylate.

In an embodiment, the thin-film encapsulation layer TFE may include a first inorganic layer310, an organic layer320, and a second inorganic layer330, which are sequentially stacked. In an embodiment, the light transmittance of at least one of the first inorganic layer310and the second inorganic layer330may be about 90% or more. In an embodiment, the first inorganic layer310may include silicon oxynitride (SiON). The second inorganic layer330may include silicon nitride (SiNX). This may be for improving the reliability of the display device1.

FIG.3Ais a schematic cross-sectional view of a portion of a display device, according to an embodiment. InFIG.3A, the same reference numerals as those inFIG.2refer to the same members, and redundant descriptions thereof will not be repeated here.

Referring toFIG.3A, the display device may include a substrate, a display element, a thin-film encapsulation layer, and a lower layer LL. The thin-film encapsulation layer may include at least one inorganic layer and at least one organic layer. In an embodiment, the thin-film encapsulation layer may include a first inorganic layer310, an organic layer320, and a second inorganic layer.

The lower layer LL may be below the thin-film encapsulation layer. For example, the lower layer LL may be below the first inorganic layer310. In this case, the first inorganic layer310may be arranged along the shape of the lower layer LL. In an embodiment, the lower layer LL may include a pixel defining layer of a display element layer to be described below. In an embodiment, the lower layer LL may include a spacer of the display element layer to be further described below. In an embodiment, the lower layer LL may include a pattern layer on the spacer of the display element layer to be further described below. The lower layer LL may include a first lower layer LL1and a second lower layer LL2.

The first lower layer LL1may include a flat upper surface LLUS. In this case, the upper surface LLUS of the first lower layer LL1may be parallel (e.g., substantially parallel) to the upper surface of the substrate. The second lower layer LL2may be on the first lower layer LL1. In an embodiment, the second lower layer LL2may be integrally formed with the first lower layer LL1. In this case, the second lower layer LL2may protrude from the first lower layer LL1. In another embodiment, the second lower layer LL2may be a layer different layer from the first lower layer LL1. In this case, the second lower layer LL2may include a material different from that of the first lower layer LL1.

The second lower layer LL2may include a first surface S1and a second surface S2. The first surface S1of the second lower layer LL2may be parallel (e.g., substantially parallel) to the upper surface of the substrate. In an embodiment, the first surface S1of the second lower layer LL2may be parallel (e.g., substantially parallel) to the upper surface LLUS of the first lower layer LL1. For example, the first surface S1of the second lower layer LL2may extend in an x direction. In some embodiments, the first surface S1of the second lower layer LL2may meet the second surface S2of the second lower layer LL2and cross (e.g., intersect with) the second surface S2of the second lower layer LL2. The following description will focus on a case in which the first surface S1of the second lower layer LL2is parallel (e.g., substantially parallel) to the upper surface of the substrate, but the present disclosure is not limited thereto.

In an embodiment, the second lower layer LL2may include an inclined second surface S2. The second surface S2of the second lower layer LL2may extend in a direction crossing (e.g., intersecting with) the upper surface of the substrate. For example, the second surface S2of the second lower layer LL2may extend in a direction crossing (e.g., intersecting with) the first surface S1of the second lower layer LL2. For example, the second surface S2of the second lower layer LL2may extend in a direction crossing (e.g., intersecting with) the x direction.

The second surface S2of the second lower layer LL2may have a taper length L. The taper length L may be defined as a distance from a point at which the second surface S2of the second lower layer LL2and the upper surface LLUS of the first lower layer LL1meet to a point at which the second surface S2of the second lower layer LL2and the first surface S1of the second lower layer LL2meets.

The first surface S1and the second surface S2of the second lower layer LL2may form an angle A therebetween. In an embodiment, the angle A between the first surface S1and the second surface S2of the second lower layer LL2may be an acute angle. In another embodiment, the angle A between the first surface S1and the second surface S2of the second lower layer LL2may be a right angle. In another embodiment, the angle A between the first surface S1and the second surface S2of the second lower layer LL2may be an obtuse angle. Because the first surface S1of the second lower layer LL2extends in a direction parallel (e.g., substantially parallel) to the upper surface of the substrate, the angle A may be defined as an angle between the second surface S2of the second lower layer LL2and the upper surface of the substrate. In some embodiments, the angle A may be defined as an angle between the upper surface LLUS of the first lower layer LL1and the second surface S2of the second lower layer LL2.FIG.3Aillustrates a case in which the angle A is an acute angle.

The first inorganic layer310may cover the first lower layer LL1and the second lower layer LL2. Also, the organic layer320may be on the first inorganic layer310. The first inorganic layer310may be on the upper surface LLUS of the first lower layer LL1and the first surface S1of the second lower layer LL2. In some embodiments, the first inorganic layer310in the first lower layer LL1and the first inorganic layer310in the second lower layer LL2may be coupled to each other. In this case, the first inorganic layer310in the first lower layer LL1and the first inorganic layer310in the second lower layer LL2may be integrally formed with each other.

The first inorganic layer310may have a first thickness d1on the first surface S1of the second lower layer LL2. The first thickness d1may be defined as the length of the first inorganic layer310in a direction perpendicular (e.g., substantially perpendicular) to the first surface S1of the second lower layer LL2. In some embodiments, the first thickness d1may be defined as the length of the first inorganic layer310in a direction perpendicular (e.g., substantially perpendicular) to the upper surface of the substrate.

The first inorganic layer310may be on the second surface S2of the second lower layer LL2. In an embodiment, because the first inorganic layer310is formed by chemical vapor deposition (CVD), the first inorganic layer310may also be formed on the second surface S2of the second lower layer LL2extending in a direction crossing (e.g., intersecting with) the first surface S1of the second lower layer LL2.

The thickness of the first inorganic layer310on the second surface S2of the second lower layer LL2may decrease as the distance to the first lower layer LL1decreases. The first inorganic layer310may be formed by CVD. In this case, the amount of gas forming the first inorganic layer310may not be suitable or sufficient as the distance to the first lower layer LL1decreases. For example, the gas forming the first inorganic layer310may not be supplied suitably or enough to form the first thickness d1at a point at which the upper surface LLUS of the first lower layer LL1and the second surface S2of the second lower layer LL2meet. Therefore, the thickness of the first inorganic layer310on the second surface S2of the second lower layer LL2may decrease as the distance to the first lower layer LL1decreases.

The first inorganic layer310may have a second thickness d2on the second surface S2of the second lower layer LL2. The second thickness d2may be defined as the length of the first inorganic layer310in a direction perpendicular (e.g., substantially perpendicular) to the second surface S2of the second lower layer LL2. In some embodiments, the second thickness d2may be defined as an average value of the thicknesses of the first inorganic layer310on the second surface S2of the second lower layer LL2. For example, the second thickness d2may be a median value of a minimum value among the thicknesses of the first inorganic layer310on the second surface S2of the second lower layer LL2and a maximum value sdmax among the thicknesses of the first inorganic layer310on the second surface S2. The maximum value sdmax may be defined as the thickness of the first inorganic layer310in a direction perpendicular (e.g., substantially perpendicular) to the second surface S2of the second lower layer LL2at a point at which the first surface S1and the second surface S2of the second lower layer LL2meet.

In an embodiment, the first thickness d1may be greater than or equal to the second thickness d2. When the first inorganic layer310is formed by CVD, the gas forming the first inorganic layer310may be more suitably or sufficiently supplied to the first surface S1of the second lower layer LL2than the second surface S2of the second lower layer LL2. Therefore, the first thickness d1may be greater than or equal to the second thickness d2. In another embodiment, the first thickness d1may be greater than the second thickness d2. When the first inorganic layer310is formed by physical vapor deposition, the first thickness d1may be greater than the second thickness d2. For example, the first inorganic layer310may be formed by sputtering or evaporation. In another embodiment, when the first inorganic layer310is formed by atomic layer deposition, the first thickness d1may be greater than, less than, or equal to the second thickness d2. The following description will focus on a case in which the first inorganic layer310is formed by CVD, but the present disclosure is not limited thereto.

The first inorganic layer310on the upper surface LLUS of the first lower layer LL1may have a third thickness d3. In an embodiment, the third thickness d3may decrease as the distance to the second lower layer LL2decreases. The first inorganic layer310may be formed by CVD. In this case, the first inorganic layer310may also be formed on the second surface S2of the second lower layer LL2. Therefore, the amount of gas forming the first inorganic layer310may decrease as the distance to the second lower layer LL2decreases, and the third thickness d3may decrease as the distance to the second lower layer LL2decreases.

A ratio of the second thickness d2to the first thickness d1may be about 0.51 or more. In this specification, the ratio of the second thickness d2to the first thickness d1may be defined as step coverage. When the ratio of the second thickness d2to the first thickness d1is less than 0.51, the first inorganic layer310may not suitably or sufficiently cover the lower layer LL. For example, the first inorganic layer310may be formed relatively thinly or may not be formed at a point at which the second surface S2of the second lower layer LL2and the upper surface LLUS of the first lower layer LL1meet. In this case, defects such as pinholes may be provided in the first inorganic layer310, and oxygen, moisture, and/or the like may be transmitted to the organic light-emitting diode through the defects of the first inorganic layer310. Therefore, dark spots may occur in the display area. When the ratio of the second thickness d2to the first thickness d1is 0.51 or more, the first inorganic layer310may suitably or sufficiently cover the lower layer LL, thereby improving the reliability of the display device. In some embodiments, the ratio of the second thickness d2to the first thickness d1may be about 0.76 or more.

The taper length L may be greater than about 0 μm and less than about 3.6 μm. When the taper length L is 0 μm, the second lower layer LL2is not defined. When the taper length L is 3.6 μm or more, the first inorganic layer310may not suitably or sufficiently cover the second surface S2of the second lower layer LL2, and defects such as pinholes may form.

FIG.3Bis a schematic cross-sectional view of a portion of a display device, according to an embodiment. InFIG.3B, the same reference numerals as those inFIG.3Arefer to the same members, and redundant descriptions thereof will not be repeated here.

Referring toFIG.3B, the display device may include a substrate, a display element, a thin-film encapsulation layer, and a lower layer LL. The thin-film encapsulation layer may include at least one inorganic layer and at least one organic layer. In an embodiment, the thin-film encapsulation layer may include a first inorganic layer310, an organic layer320, and a second inorganic layer.

The second lower layer LL2may include a first surface S1and a second surface S2, and the first surface S1and the second surface S2of the second lower layer LL2may form an angle A therebetween. In this case, the angle A between the first surface S1and the second surface S2may be a right angle or an obtuse angle.

The first inorganic layer310may cover the first lower layer LL1and the second lower layer LL2. Also, the organic layer320may be on the first inorganic layer310.

The first inorganic layer310may have a first thickness d1on the first surface S1of the second lower layer LL2. Also, the first inorganic layer310may be on the second surface S2of the second lower layer LL2. The first inorganic layer310may have a second thickness d2on the second surface S2of the second lower layer LL2. The second thickness d2may be defined as the length of the first inorganic layer310in a direction perpendicular (e.g., substantially perpendicular) to the second surface S2of the second lower layer LL2. In some embodiments, the second thickness d2may be defined as an average value of the thicknesses of the first inorganic layer310on the second surface S2of the second lower layer LL2.

In an embodiment, the first thickness d1may be greater than or equal to the second thickness d2. In an embodiment, the first inorganic layer310may be formed by CVD. When the angle A between the first surface S1and the second surface S2of the second lower layer LL2is a right angle or an obtuse angle, gas forming the first inorganic layer310may be suitably or sufficiently supplied to the second surface S2of the second lower layer LL2. In this case, in some embodiments, the first thickness d1and the second thickness d2may be substantially equal to each other. In another embodiment, the first thickness d1may be greater than the second thickness d2. When the first inorganic layer310is formed by physical vapor deposition, the first thickness d1may be greater than the second thickness d2. For example, the first inorganic layer310may be formed by sputtering or evaporation. In another embodiment, when the first inorganic layer310is formed by atomic layer deposition, the first thickness d1may be greater than, less than, or equal to the second thickness d2. The following description will focus on a case in which the first inorganic layer310is formed by CVD, but the present disclosure is not limited thereto.

In an embodiment, a third thickness d3may be equal to the first thickness d1on the first surface S1of the second lower layer LL2.

FIG.3Cis a schematic cross-sectional view of a portion of a display device, according to an embodiment. InFIG.3C, the same reference numerals as those inFIG.3Arefer to the same members, and redundant descriptions thereof will not be repeated here.

Referring toFIG.3C, the display device may include a substrate, a display element, a thin-film encapsulation layer, and a lower layer LL. The thin-film encapsulation layer may include at least one inorganic layer and at least one organic layer. In an embodiment, the thin-film encapsulation layer may include a first inorganic layer310, an organic layer320, and a second inorganic layer.

The lower layer LL may be below the thin-film encapsulation layer. For example, the lower layer LL may be below the first inorganic layer310. In this case, the first inorganic layer310may be arranged along the shape of the lower layer LL.

The second lower layer LL2may include a curved surface CS. For example, the second lower layer LL2may have a semicircle, a half ellipse, or an arc shape. In some embodiments, at least a portion of the second lower layer LL2may include a curved portion. The curved surface CS of the second lower layer LL2may include a first surface S1and a second surface S2. The first surface S1of the second lower layer LL2may be defined as an area in which a tangent line TL to the curved surface CS of the second lower layer LL2extends in a direction parallel (e.g., substantially parallel) to the upper surface of the substrate. In an embodiment, the first surface S1of the second lower layer LL2may be defined as any one point. The second surface S2of the second lower layer LL2may be defined as an area in which the tangent line TL to the curved surface CS of the second lower layer LL2extends in a direction crossing (e.g., intersecting with) the upper surface of the substrate. Therefore, the second surface S2of the second lower layer LL2may be an area of the second lower layer LL2excluding the first surface S1of the second lower layer LL2.

The first inorganic layer310may cover the first lower layer LL1and the second lower layer LL2. Also, the organic layer320may be on the first inorganic layer310.

The first inorganic layer310may be on the curved surface CS of the second lower layer LL2. For example, the first inorganic layer310may have a first thickness d1on the first surface S1of the second lower layer LL2. The first thickness d1may be defined as the length of the first inorganic layer310in a direction normal to the first surface S1of the second lower layer LL2. For example, the first thickness d1may be defined as the length of the first inorganic layer310in a direction perpendicular (e.g., substantially perpendicular) to the tangent line TL to the curved surface CS of the second lower layer LL2.

The first inorganic layer310may have a second thickness d2on the second surface S2of the second lower layer LL2. The second thickness d2may be defined as the length of the first inorganic layer310in a direction normal to the second surface S2of the second lower layer LL2. For example, the second thickness d2may be defined as an average value of the thicknesses of the first inorganic layer310on the second surface S2of the second lower layer LL2.

In an embodiment, the first thickness d1may be greater than or equal to the second thickness d2. In some embodiments, the first thickness d1and the second thickness d2may be substantially equal to each other. In another embodiment, the first thickness d1may be greater than the second thickness d2. When the first inorganic layer310is formed by physical vapor deposition, the first thickness d1may be greater than the second thickness d2. For example, the first inorganic layer310may be formed by sputtering and/or evaporation (e.g., deposition). In another embodiment, when the first inorganic layer310is formed by atomic layer deposition, the first thickness d1may be greater than, less than, or equal to the second thickness d2. The following description will focus on a case in which the first inorganic layer310is formed by CVD, but the present disclosure is not limited thereto. Also, in an embodiment, a third thickness d3may be equal to the first thickness d1on the first surface S1of the second lower layer LL2.

The following description will focus on a case in which the second lower layer LL2has a polygonal shape, as illustrated inFIGS.3A and3B, but the present disclosure is not limited thereto.

FIG.4is a graph showing dark spot defects according to the angle A and the step coverage SC.

Referring toFIG.4, when the step coverage SC was 0.51 or less, dark spot defects all occurred. Also, when the angle A was 42° or less, dark spot defects all occurred. Therefore, when the step coverage SC is 0.51 or more, the probability of occurrence of dark spot defects may be substantially or significantly reduced and the reliability of the display device may be improved.

Also, when the step coverage SC was 0.76 or more, no dark spot defects occurred. Also, when the angle A was 88° or more, no dark spot defects occurred. Therefore, when the step coverage SC is 0.76 or more, no dark spot defects occur and the reliability of the display device may be improved.

FIG.5Ais a graph showing the composition ratio of an inorganic layer according to step coverage.

Referring toFIG.5A, the inorganic layer may include SiXOYNZ. As the step coverage of the inorganic layer increases, a composition ratio (Y/X) of oxygen to silicon in the inorganic layer (SiXOYNZ) may increase. For example, when the step coverage of the inorganic layer is greater than 0.41, the composition ratio (Y/X) of oxygen to silicon in the inorganic layer (SiXOYNZ) may be greater than about 0.

The composition ratio (Y/X) of oxygen to silicon in the inorganic layer (SiXOYNZ) may be greater than about 0.5. When the composition ratio (Y/X) of oxygen to silicon in the inorganic layer (SiXOYNZ) is greater than 0.5, the step coverage may be greater than 0.51 and the probability of occurrence of dark spot defects in the display device may be substantially or significantly reduced.

As the step coverage of the inorganic layer increases, a composition ratio (Z/X) of nitrogen to silicon in the inorganic layer (SiXOYNZ) may decrease.

The composition ratio (Z/X) of nitrogen to silicon in the inorganic layer (SiXOYNZ) may be less than or equal to about 0.5. Also, the composition ratio (Z/X) of nitrogen to silicon in the inorganic layer (SiXOYNZ) may be greater than about 0. When the composition ratio (Z/X) of nitrogen to silicon in the inorganic layer (SiXOYNZ) is less than or equal to 0.5, the step coverage may be greater than 0.51 and the probability of occurrence of dark spot defects in the display device may be substantially or significantly reduced.

FIG.5Bis a graph of the water vapor transmission rate (WVTR) of an inorganic layer according to step coverage.

Referring toFIG.5B, as the step coverage of the inorganic layer increases, the WVTR of the inorganic layer may increase. The WVTR refers to the amount of water vapor permeating through the inorganic layer per unit area and unit time.

When the inorganic layer includes silicon oxynitride (SiON), the step coverage may be greater than 0.41 and the WVTR may be greater than 0.0001 g/m2/day. Therefore, when the inorganic layer includes silicon oxynitride (SiON), the step coverage may be improved, but the WVTR may increase, as compared with a case in which the inorganic layer includes silicon nitride (SiNX).

When the inorganic layer includes silicon nitride (SiNX), the step coverage may be less than 0.41 and the WVTR may be less than 0.0001 g/m2/day.FIG.5Billustrates that the WVTR of silicon nitride (SiNX) is about 0.0001 g/m2/day, but this is due to the measurement limit, and the actual WVTR of silicon nitride (SiNX) may be less than 0.0001 g/m2/day. Therefore, when the inorganic layer includes silicon nitride (SiNX), the WVTR may be low, but the step coverage may decrease, as compared with a case in which the inorganic layer includes silicon oxynitride (SiON).

FIG.5Cis a graph of stress and a WVTR according to the refractive index of an inorganic layer.

Referring toFIG.5C, when the inorganic layer includes silicon oxynitride (SiON), the refractive index may be low, as compared with a case in which the inorganic layer includes silicon nitride (SiNX). When the inorganic layer includes silicon oxynitride (SiON), the refractive index of the inorganic layer may be greater than or equal to 1.48 and less than or equal to 1.77. When the inorganic layer includes silicon nitride (SiNX), the refractive index of the inorganic layer may be greater than or equal to 1.92 and less than or equal to 1.97.

As the refractive index of the inorganic layer increases, a magnitude of a stress may increase. The stress described herein represents the magnitude of the force per unit area that the inorganic layer has (or is subjected to), and includes a compressive stress or a tensile stress. In this specification, the compressive stress is expressed as a negative number and the tensile stress is expressed as a positive number. The magnitude of the stress when the inorganic layer includes silicon oxynitride (SiON) may be less than that when the inorganic layer includes silicon nitride (SiNX). The magnitude of the stress, as described herein, means the absolute value of the stress. Therefore, in order to prevent or reduce buckling, a thickness of the inorganic layer when the inorganic layer includes silicon nitride (SiNX) may be less than a thickness of the inorganic layer when the inorganic layer includes silicon oxynitride (SiON). The magnitude of the stress and the refractive index when the inorganic layer includes silicon oxynitride (SiON) may be less than those when the inorganic layer includes silicon nitride (SiNX).

As the refractive index of the inorganic layer increases, the WVTR may decrease. For example, the WVTR when the inorganic layer includes silicon oxynitride (SiON) may be higher than that when the inorganic layer includes silicon nitride (SiNx). Therefore, when the inorganic layer includes silicon oxynitride (SiON), the refractive index may be small and the WVTR may be high, as compared with a case in which the inorganic layer includes silicon nitride (SiNx).

FIG.5Dis a graph showing step coverage according to refractive index.

Referring toFIG.5D, as the refractive index of the inorganic layer increases, the step coverage of the inorganic layer may decrease. For example, the refractive index when the inorganic layer includes silicon oxynitride (SiON) may be less than that when the inorganic layer includes silicon nitride (SiNX). Also, the step coverage when the inorganic layer includes silicon oxynitride (SiON) may be greater than the step coverage when the inorganic layer includes silicon nitride (SiNX).

When the inorganic layer includes silicon oxynitride (SiON) and has a refractive index of greater than or equal to 1.48 and less than or equal to 1.71, the step coverage may be greater than 0.51. In this case, the probability of occurrence of dark spot defects in the display device may be substantially or significantly reduced.

Referring toFIGS.5A to5D, as the refractive index of the inorganic layer increases, the magnitude of the stress may increase. Also, as the refractive index of the inorganic layer increases, the WVTR may decrease. Furthermore, as the refractive index of the inorganic layer increases, the step coverage may decrease.

FIG.5Eis a graph showing a refractive index and step coverage according to a condition in which an inorganic layer is formed.FIG.5Eillustrates a case in which the inorganic layer includes silicon oxynitride (SiON).

Referring toFIG.5E, the inorganic layer may be formed by CVD. When the inorganic layer includes silicon oxynitride (SiON), the inorganic layer may be formed using nitrous oxide (N2O) and ammonia (NH3). For example, a display device being manufactured may be charged into a chamber. A concentration of nitrous oxide (N2O) and a concentration of ammonia (NH3) may be set in the chamber. In an embodiment, an oxygen composition ratio of silicon oxynitride (SiON) may increase as the concentration of nitrous oxide (N2O) increases. In an embodiment, an oxygen composition ratio of silicon oxynitride (SiON) may increase as the concentration of ammonia (NH3) increases.

As the concentration of nitrous oxide (N2O) increases compared to the concentration of ammonia (NH3), the step coverage of the inorganic layer may increase. For example, when the concentration of nitrous oxide (N2O) is four or more times higher than the concentration of ammonia (NH3), the step coverage of the inorganic layer may be greater than or equal to 0.51. In this case, the probability of occurrence of dark spot defects in the display device may be substantially or significantly reduced. Also, as the concentration of nitrous oxide (N2O) increases compared to the concentration of ammonia (NH3), the refractive index of the inorganic layer may increase.

FIG.6is a schematic cross-sectional view of a display device according to an embodiment. InFIG.6, the same reference numerals as those inFIG.2refer to the same members, and redundant descriptions thereof will not be repeated here.

Referring toFIG.6, the display device may include a substrate100, a pixel circuit layer PCL, a display element layer DEL, and a thin-film encapsulation layer TFE. A lower layer LL-1may be below the thin-film encapsulation layer TFE. The pixel circuit layer PCL may include a buffer layer111, a thin-film transistor TFT, an inorganic insulating layer IIL, and a planarization layer115. The inorganic insulating layer IIL may include a first gate insulating layer112, a second gate insulating layer113, and an interlayer insulating layer114. The display element layer DEL may include an organic light-emitting diode OLED. The thin-film encapsulation layer TFE may include a first inorganic layer310, an organic layer320, and a second inorganic layer330.

The buffer layer111may be on the substrate100. The buffer layer111may include an inorganic insulating material such as silicon nitride (SiNX), silicon oxynitride (SiON), and silicon oxide (SiO2), and may include a single layer or multiple layers including the above-described inorganic insulating material.

The thin-film transistor TFT may include a semiconductor layer Act, a gate electrode GE, a source electrode SE, and a drain electrode DE. The semiconductor layer Act may include polysilicon, the semiconductor layer Act may include amorphous silicon, semiconductor oxide, and/or organic semiconductor. The semiconductor layer Act may include a channel region Act1, and a source region Act2and a drain region Act3, which are on both sides of the channel region Act1. The gate electrode GE may overlap the channel region Act1.

The gate electrode GE may include a low resistance metal material. The gate electrode GE may include a conductive material such as molybdenum (Mo), aluminum (Al), copper (Cu), and/or titanium (Ti), and may include a single layer or multiple layers including the above-described material.

The first gate insulating layer112between the semiconductor layer Act and the gate electrode GE may include an inorganic insulating material such as silicon oxide (SiO2), silicon nitride (SiNX), silicon oxynitride (SiON), aluminum oxide (Al2O3), titanium oxide (TiO2), tantalum oxide (Ta2O5), hafnium oxide (HfO2), and/or zinc oxide (ZnO).

The second gate insulating layer113may cover the gate electrode GE. Similarly to the first gate insulating layer112, the second gate insulating layer113may include an inorganic insulating material such as silicon oxide (SiO2), silicon nitride (SiNX), silicon oxynitride (SiON), aluminum oxide (Al2O3), titanium oxide (TiO2), tantalum oxide (Ta2O5), hafnium oxide (HfO2), and/or zinc oxide (ZnO).

An upper electrode CE2of a storage capacitor Cst may be above the second gate insulating layer113. The upper electrode CE2may overlap the gate electrode GE therebelow. In this case, the gate electrode GE and the upper electrode CE2overlapping each other with the second gate insulating layer113therebetween may form the storage capacitor Cst of a pixel circuit PC. For example, the gate electrode GE may function as a lower electrode CE1of the storage capacitor Cst.

As such, the storage capacitor Cst may overlap the thin-film transistor TFT. In some embodiments, the storage capacitor Cst may not overlap the thin-film transistor TFT.

The upper electrode CE2may include aluminum (Al), platinum (Pt), palladium (Pd), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), calcium (Ca), molybdenum (Mo), titanium (Ti), tungsten (W), and/or copper (Cu) and may include a single layer or multiple layers including the above-described material.

The interlayer insulating layer114may cover the upper electrode CE2. The interlayer insulating layer114may include silicon oxide (SiO2), silicon nitride (SiNX), silicon oxynitride (SiON), aluminum oxide (Al2O3), titanium oxide (TiO2), tantalum oxide (Ta2O5), hafnium oxide (HfO2), and/or zinc oxide (ZnO). The interlayer insulating layer114may include a single layer or multiple layers including the above-described inorganic insulating material.

The drain electrode DE and the source electrode SE may be on the interlayer insulating layer114. The drain electrode DE and the source electrode SE may each include a material having good conductivity (e.g., good electrical conductivity). The drain electrode DE and the source electrode SE may each include a conductive material including molybdenum (Mo), aluminum (Al), copper (Cu), titanium (Ti), and/or the like and may each include a single layer or multiple layers including the above-described material. In an embodiment, the drain electrode DE and the source electrode SE may each have a multiple layer structure of Ti/Al/Ti.

The planarization layer115may cover the drain electrode DE and the source electrode SE. The planarization layer115may include an organic insulating layer. The planarization layer115may include an organic insulating material such as a general-purpose polymer (e.g., polymethylmethacrylate (PMMA), polystyrene (PS), etc.) a polymer derivative having a phenol-based group, an acryl-based polymer, an aryl ether-based polymer, an amide-based polymer, a fluorine-based polymer, a p-xylene-based polymer, a vinyl alcohol-based polymer, and any blend thereof.

The display element layer DEL may be on the pixel circuit layer PCL. The display element layer DEL includes the organic light-emitting diode OLED, and a pixel electrode211of the organic light-emitting diode OLED may be electrically coupled to the source electrode SE or the drain electrode DE of the thin-film transistor TFT through a contact hole of the planarization layer115.

The pixel electrode211may include a conductive oxide such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium oxide (In2O3), indium gallium oxide (IGO), and/or aluminum zinc oxide (AZO). In another embodiment, the pixel electrode211may include a reflective layer including silver (Ag), magnesium (Mg), aluminum (Al), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), or any compound, alloy, and/or mixture thereof. In another embodiment, the pixel electrode211may further include a layer including ITO, IZO, ZnO, and/or In2O3above and/or below the reflective layer.

A pixel defining layer220having an opening220OP exposing a central portion of the pixel electrode211may be on the pixel electrode211. The pixel defining layer220may include an organic insulating material and/or an inorganic insulating material. The opening220OP may define an emission area in which light is emitted from the organic light-emitting diode OLED.

An emission layer212may be in the opening220OP of the pixel defining layer220. The emission layer212may include a high molecular weight organic material and/or a low molecular weight organic material, which emits light of a set or certain color.

In some embodiments, a first functional layer and a second functional layer may be below and above the emission layer212, respectively. For example, the first functional layer may include a hole transport layer (HTL), or may include an HTL and a hole injection layer (HIL). The second functional layer is an optional element on the emission layer212. The second functional layer may include an electron transport layer (ETL) and/or an electron injection layer (EIL). The first functional layer and/or the second functional layer may be a common layer covering the entire substrate100, as in an opposite electrode213to be further described below.

The opposite electrode213may include a conductive (e.g., electrically conductive) material having a relatively low work function. For example, the opposite electrode213may include a (semi)transparent layer including silver (Ag), magnesium (Mg), aluminum (Al), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), lithium (Li), calcium (Ca), or any alloy, mixture, and/or combination thereof. In some embodiments, the opposite electrode213may further include a layer such as ITO, IZO, ZnO, or In2O3on the (semi)transparent layer including the above-described material.

In some embodiments, a capping layer may be further on the opposite electrodes213. The capping layer may include LiF, an inorganic material, and/or an organic material.

The thin-film encapsulation layer TFE may be on the opposite electrode213. In an embodiment, the thin-film encapsulation layer TFE includes at least one inorganic layer and at least one organic layer, andFIG.6illustrates that the thin-film encapsulation layer TFE includes the first inorganic layer310, the organic layer320, and the second inorganic layer330, which are sequentially stacked.

The lower layer LL-1may be below the thin-film encapsulation layer TFE. For example, the lower layer LL-1may be below the first inorganic layer310. The lower layer LL-1may include the pixel defining layer220. In this case, the first inorganic layer310may be arranged along the shape of the pixel defining layer220.

The lower layer LL-1may include a first surface S1-1and a second surface S2-1. The first surface S1-1of the lower layer LL-1may be parallel (e.g., substantially parallel) to an upper surface100US of the substrate100. In an embodiment, the first surface S1-1of the lower layer LL-1may be parallel (e.g., substantially parallel) to the upper surface of the planarization layer115or the upper surface of the pixel electrode211. For example, the first surface S1-1of the lower layer LL-1may extend in an x direction.

The lower layer LL-1may include an inclined second surface S2-1. In an embodiment, the second surface S2-1of the lower layer LL-1may define an inner surface of the opening2200P. The second surface S2-1of the lower layer LL-1may extend in a direction crossing (e.g., intersecting with) the upper surface100US of the substrate100. For example, the second surface S2-1of the lower layer LL-1may extend in a direction crossing (e.g., intersecting with) the first surface S1-1of the lower layer LL-1. For example, the second surface S2-1of the lower layer LL-1may extend in a direction crossing (e.g., intersecting with) the x direction.

The first surface S1-1and the second surface S2-1of the lower layer LL-1may form an angle A-1therebetween. Because the first surface S1-1of the lower layer LL-1extends in a direction parallel (e.g., substantially parallel) to the upper surface100US of the substrate100, the angle A-1may be defined as an angle between the second surface S2-1of the lower layer LL-1and the upper surface100US of the substrate100.

In an embodiment, the angle A-1between the first surface S1-1and the second surface S2-1of the lower layer LL-1may be an obtuse angle or a right angle. In an embodiment, the angle A-1between the first surface S1-1and the second surface S2-1of the lower layer LL-1may be an acute angle.

The first inorganic layer310may be on the curved lower layer LL-1. For example, the first inorganic layer310may cover the first surface S1-1and the second surface S2-1of the lower layer LL-1. In this case, the first inorganic layer310may have a first thickness d1-1on the first surface S1-1of the lower layer LL-1. The first thickness d1-1may be defined as the length of the first inorganic layer310in a direction perpendicular (e.g., substantially perpendicular) to the first surface S1of the lower layer LL-1. In some embodiments, the first thickness d1-1may be defined as the length of the first inorganic layer310in a direction perpendicular (e.g., substantially perpendicular) to the upper surface100US of the substrate100.

The first inorganic layer310may have a second thickness d2-1on the second surface S2-1of the lower layer LL-1. The second thickness d2-1may be defined as the length of the first inorganic layer310in a direction perpendicular (e.g., substantially perpendicular) to the second surface S2-1of the lower layer LL-1. For example, the second thickness d2-1may be defined as an average value of the thicknesses of the first inorganic layer310on the second surface S2-1of the lower layer LL-1.

In an embodiment, the first thickness d1-1may be greater than or equal to the second thickness d2-1. When the first inorganic layer310is formed by CVD, the first thickness d1-1may be greater than or equal to the second thickness d2-1. In some embodiments, the first thickness d1-1and the second thickness d2-1may be substantially equal to each other. In another embodiment, the first thickness d1-1may be greater than the second thickness d2-1. When the first inorganic layer310is formed by physical vapor deposition, the first thickness d1-1may be greater than the second thickness d2-1. In another embodiment, the first thickness d1-1may be greater than, less than, or equal to the second thickness d2-1. When the first inorganic layer310is formed by atomic layer deposition, the first thickness d1-1may be greater than, less than, or equal to the second thickness d2-1.

A ratio of the second thickness d2-1to the first thickness d1-1may be about 0.51 or more. For example, the step coverage may be about 0.51 or more. In some embodiments, the ratio of the second thickness d2-1to the first thickness d1-1may be about 0.76 or more. Therefore, the first inorganic layer310may suitably or sufficiently cover the pixel defining layer220and the organic light-emitting diode OLED, and the reliability of the display device may be improved.

In an embodiment, the first inorganic layer310may include silicon oxynitride (SiON). When the first inorganic layer310includes silicon oxynitride (SiON) and a composition ratio of oxygen to silicon is greater than 0.5, the step coverage of the first inorganic layer310may be 0.51 or more. Therefore, the reliability of the display device may be improved.

The refractive index of the first inorganic layer310may be lower than the refractive index of the second inorganic layer330. Also, the refractive index of the organic layer320may be lower than the refractive index of the second inorganic layer330. The first inorganic layer310is a layer closest to the organic light-emitting diode OLED in the thin-film encapsulation layer TFE. When the refractive index of the first inorganic layer310is relatively lower than the refractive index of the second inorganic layer330, the extraction efficiency of light emitted from the organic light-emitting diode OLED may be improved. Also, when the refractive index of the first inorganic layer310is relatively lower than the refractive index of the second inorganic layer330, the white angle difference (WAD) of light emitted from the organic light-emitting diode OLED may be improved. Also, when the light absorption coefficient of the first inorganic layer310is low, the extraction efficiency of light emitted from the organic light-emitting diode OLED may be improved. When the first inorganic layer310includes silicon oxynitride (SiON), the first inorganic layer310has a relatively smaller refractive index and a smaller light absorption coefficient than those when the first inorganic layer310includes silicon nitride (SiNX). Therefore, the extraction efficiency of light emitted from the organic light-emitting diode OLED may be improved.

The organic layer320may be on the first inorganic layer310and may cover the first inorganic layer310. In this case, the upper surface of the organic layer320may be flat.

The second inorganic layer330may be on the organic layer320. The second inorganic layer330may be on the flat upper surface of the organic layer320. Therefore, the step coverage of the second inorganic layer330may be less important than the step coverage of the first inorganic layer310.

In an embodiment, the second inorganic layer330may include silicon nitride (SiNX). Therefore, the WVTR of the second inorganic layer330may be less than the WVTR of the first inorganic layer310, and the second inorganic layer330may function as a barrier layer.

As such, the first inorganic layer310and the second inorganic layer330may include different materials from each other. For example, the first inorganic layer310may include silicon oxynitride (SiON) so as to have relatively high step coverage, and the second inorganic layer330may include silicon nitride (SiNX) so as to have a relatively low WVTR. Therefore, the reliability of the display device may be improved.

A thickness330dof the second inorganic layer330may be less than a first thickness d1-1of the first inorganic layer310. When the second inorganic layer330includes a material having a low WVTR, the stress of the second inorganic layer330may be higher than the stress of the first inorganic layer310. Therefore, a buckling phenomenon may occur in the second inorganic layer330, as compared with the first inorganic layer310. In this case, because the thickness330dof the second inorganic layer330is less than the first thickness d1-1of the first inorganic layer310, occurrence of a buckling phenomenon may be prevented or reduced.

In some embodiments, a touch electrode layer may be on the thin-film encapsulation layer TFE, and an optical functional layer may be on the touch electrode layer. The touch electrode layer may obtain coordinate information according to an external input, for example, a touch event. The optical functional layer may reduce reflectance of light (external light) incident from the outside toward the display device, and/or may improve color purity of light emitted from the display device. In an embodiment, the optical functional layer may include a retarder and/or a polarizer. The retarder may be a film type retarder (e.g., a film kind of retarder) or a liquid crystal coating type retarder (e.g., a liquid crystal coating kind of retarder) and may include a λ/2 retarder and/or a λ/4 retarder. The polarizer may also be a film type polarizer (e.g., a film kind of polarizer) or a liquid crystal coating type polarizer (e.g., a liquid crystal coating kind of polarizer). The film type polarizer (e.g., the film kind of polarizer) may include a stretched synthetic resin film, and the liquid crystal coating type polarizer (e.g., the liquid crystal coating kind of polarizer) may include liquid crystals arranged in a set or certain array. The retarder and the polarizer may each further include a protective film.

In another embodiment, the optical functional layer may include a black matrix and color filters. The color filters may be arranged considering the color of light emitted from each pixel of the display device. The color filters may each include a red, green, and/or blue pigment and/or dye. In some embodiments, the color filters may each further include, in addition to the pigment or dye, quantum dots. In some embodiments, some color filters may not include the pigment or dye and may include scattering particles such as titanium oxide.

In another embodiment, the optical functional layer may include a destructive interference structure. The destructive interference structure may include a first reflective layer and a second reflective layer, which are on different layers from each other. First reflected light and second reflected light respectively reflected from the first reflective layer and the second reflective layer may destructively interfere with each other, and thus, the reflectance of external light may be reduced.

An adhesive member may be between the touch electrode layer and the optical functional layer. The adhesive member may be employed without being limited to those commonly used in the art. The adhesive member may include a pressure sensitive adhesive (PSA).

FIG.7is a schematic cross-sectional view of a display device according to an embodiment. InFIG.7, the same reference numerals as those inFIG.6refer to the same members, and redundant descriptions thereof will not be repeated here.

Referring toFIG.7, the display device may include a substrate100, a pixel circuit layer PCL, a display element layer DEL, and a thin-film encapsulation layer TFE. A lower layer LL-2may be below the thin-film encapsulation layer TFE. The pixel circuit layer PCL may include a buffer layer111, a thin-film transistor TFT, an inorganic insulating layer IIL, and a planarization layer115. The inorganic insulating layer IIL may include a first gate insulating layer112, a second gate insulating layer113, and an interlayer insulating layer114. The display element layer DEL may include an organic light-emitting diode OLED. The thin-film encapsulation layer TFE may include a first inorganic layer310, an organic layer320, and a second inorganic layer330.

The lower layer LL-2may be below an opposite electrode213and the thin-film encapsulation layer TFE. For example, the lower layer LL-2may be below the opposite electrode213and the first inorganic layer310. The lower layer LL-2may include a spacer230. The spacer230may be on a pixel defining layer220. The spacer230may prevent or reduce damage to at least one of the substrate100, the pixel circuit layer PCL, and the display element layer DEL in a method of manufacturing the display device. In a method of manufacturing an organic light-emitting diode OLED, a mask sheet may be used. At least one of the substrate100, the pixel circuit layer PCL, and the display element layer DEL may be damaged by the mask sheet. When an emission layer212is formed, the spacer230may separate the mask sheet from at least one of the substrate100, the pixel circuit layer PCL, and the display element layer DEL. Therefore, the spacer230may prevent or reduce breakage or damage to at least one of the substrate100, the pixel circuit layer PCL, and the display element layer DEL.

The spacer230may include an organic material such as polyimide. In some embodiments, the spacer230may include an inorganic insulating material such as silicon nitride (SiNx) or silicon oxide (SiO2) or may include an organic insulating material and an inorganic insulating material.

In an embodiment, the spacer230may include a material different from that of the pixel defining layer220. In another embodiment, the spacer230may include the same (e.g., substantially the same) material as that of the pixel defining layer220. In this case, the pixel defining layer220and the spacer230may be formed together in a mask process using a halftone mask and/or the like.

The lower layer LL-2may include a first surface S1-2and a second surface S2-2. The first surface S1-2of the lower layer LL-2may be parallel (e.g., substantially parallel) to an upper surface100US of the substrate100. In an embodiment, the first surface S1-2of the lower layer LL-2may be parallel (e.g., substantially parallel) to the upper surface of the pixel electrode221. For example, the first surface S1-2of the lower layer LL-2may extend in an x direction.

The lower layer LL-2may include an inclined second surface S2-2. The second surface S2-2of the lower layer LL-2may extend in a direction crossing (e.g., intersecting with) the upper surface100US of the substrate100. For example, the second surface S2-2of the lower layer LL-2may extend in a direction crossing (e.g., intersecting with) the first surface S1-2of the lower layer LL-2. For example, the second surface S2-2of the lower layer LL-2may extend in a direction crossing (e.g., intersecting with) the x direction.

The first surface S1-2and the second surface S2-2of the lower layer LL-2may form an angle A-2therebetween. Because the first surface S1-2of the lower layer LL-2extends in a direction parallel (e.g., substantially parallel) to the upper surface100US of the substrate100, the angle A-2may be defined as an angle between the second surface S2-2of the lower layer LL-2and the upper surface100US of the substrate100.

In an embodiment, the angle A-2between the first surface S1-2and the second surface S2-2of the lower layer LL-2may be an obtuse angle or a right angle. In an embodiment, the angle A-2between the first surface S1-2and the second surface S2-2of the lower layer LL-2may be an acute angle.

The first inorganic layer310may cover the first surface S1-2and the second surface S2-2of the lower layer LL-2. In this case, the first inorganic layer310may have a first thickness d1-2on the first surface S1-2of the lower layer LL-2. The first thickness d1-2may be defined as the length of the first inorganic layer310in a direction perpendicular (e.g., substantially perpendicular) to the first surface S1-2of the lower layer LL-2. In some embodiments, the first thickness d1-2may be defined as the length of the first inorganic layer310in a direction perpendicular (e.g., substantially perpendicular) to the upper surface100US of the substrate100.

The first inorganic layer310may have a second thickness d2-2on the second surface S2-2of the lower layer LL-2. The second thickness d2-2may be defined as the length of the first inorganic layer310in a direction perpendicular (e.g., substantially perpendicular) to the second surface S2-2of the lower layer LL-2. For example, the second thickness d2-2may be defined as an average value of the thicknesses of the first inorganic layer310on the second surface S2-2of the lower layer LL-2.

In an embodiment, the first thickness d1-2may be greater than or equal to the second thickness d2-2. When the first inorganic layer310is formed by physical vapor deposition, the first thickness d1-2may be greater than or equal to the second thickness d2-2. In some embodiments, the first thickness d1-2and the second thickness d2-2may be substantially equal to each other. In another embodiment, the first thickness d1-2may be greater than the second thickness d2-2. When the first inorganic layer310is formed by physical vapor deposition, the first thickness d1-2may be greater than the second thickness d2-2. In another embodiment, the first thickness d1-2may be greater than, less than, or equal to the second thickness d2-2. When the first inorganic layer310is formed by atomic layer deposition, the first thickness d1-2may be greater than, less than, or equal to the second thickness d2-2.

A ratio of the second thickness d2-2to the first thickness d1-2may be about 0.51 or more. For example, the step coverage may be about 0.51 or more. In some embodiments, the ratio of the second thickness d2-2to the first thickness d1-2may be about 0.76 or more. Therefore, the first inorganic layer310may suitably or sufficiently cover the pixel defining layer220, the spacer230, and the organic light-emitting diode OLED, and the reliability of the display device may be improved.

FIG.8is a schematic cross-sectional view of a display device according to an embodiment. InFIG.8, the same reference numerals as those inFIG.7refer to the same members, and redundant descriptions thereof will not be repeated here.

Referring toFIG.8, the display device may include a substrate100, a pixel circuit layer PCL, a display element layer DEL, and a thin-film encapsulation layer TFE. A lower layer LL-3may be below the thin-film encapsulation layer TFE. The pixel circuit layer PCL may include a buffer layer111, a thin-film transistor TFT, an inorganic insulating layer IIL, and a planarization layer115. The inorganic insulating layer IIL may include a first gate insulating layer112, a second gate insulating layer113, and an interlayer insulating layer114. The display element layer DEL may include an organic light-emitting diode OLED. The thin-film encapsulation layer TFE may include a first inorganic layer310, an organic layer320, and a second inorganic layer330.

The lower layer LL-3may be below an opposite electrode213and the thin-film encapsulation layer TFE. For example, the lower layer LL-3may be below the opposite electrode213and the first inorganic layer310. The lower layer LL-3may be on a spacer230. In an embodiment, the lower layer LL-3may include a pattern layer240. The pattern layer240may include the same (e.g., substantially the same) material as that of an emission layer212. In a method of manufacturing an organic light-emitting diode OLED, a mask sheet may be used to form the emission layer212. At this time, the mask sheet may be reused, and the material forming the emission layer may remain in the reused mask sheet. In this case, when the mask sheet is close to the spacer230, the pattern layer240may be formed on the spacer230by the material.

The lower layer LL-3may include a first surface S1-3and a second surface S2-3. In an embodiment, the first surface S1-3of the lower layer LL-3may be parallel (e.g., substantially parallel) to an upper surface100US of the substrate100. In an embodiment, the first surface S1-3of the lower layer LL-3may be parallel (e.g., substantially parallel) to the upper surface of the spacer230. For example, the first surface S1-3of the lower layer LL-3may extend in an x direction. In an embodiment, the first surface S1-3of the lower layer LL-3may meet the second surface S2-3of the lower layer LL-3and crossing (e.g., intersect with) the second surface S2-3of the lower layer LL-3.

The lower layer LL-3may include an inclined second surface S2-3. The second surface S2-3of the lower layer LL-3may extend in a direction crossing (e.g., intersecting with) the upper surface100US of the substrate100. For example, the second surface S2-3of the lower layer LL-3may extend in a direction crossing (e.g., intersecting with) the first surface S1-3of the lower layer LL-3. For example, the second surface S2-3of the lower layer LL-3may extend in a direction crossing (e.g., intersecting with) the x direction.

The first surface S1-3and the second surface S2-3of the lower layer LL-3may form an angle A-3therebetween. Because the first surface S1-3of the lower layer LL-3extends in a direction parallel (e.g., substantially parallel) to the upper surface100US of the substrate100, the angle A-3may be defined as an angle between the second surface S2-3of the lower layer LL-3and the upper surface100US of the substrate100. In some embodiments, the angle A-3may be defined as an angle between the upper surface of the spacer230and the second surface S2-3of the lower layer LL-3.

In an embodiment, the angle A-3between the first surface S1-3and the second surface S2-3of the lower layer LL-3may be an acute angle. In an embodiment, the angle A-3between the first surface S1-3and the second surface S2-3of the lower layer LL-3may be an obtuse angle or a right angle. For example, the angle A-3between the first surface S1-3and the second surface S2-3of the lower layer LL-3may be 42° or more. In another example, the angle A-3between the first surface S1-3and the second surface S2-3of the lower layer LL-3may be 88° or more.

The first inorganic layer310may cover the first surface S1-3and the second surface S2-3of the lower layer LL-3. In this case, the first inorganic layer310may have a first thickness d1-3on the first surface S1-3of the lower layer LL-3. The first thickness d1-3may be defined as the length of the first inorganic layer310in a direction perpendicular (e.g., substantially perpendicular) to the first surface S1-3of the lower layer LL-3. In some embodiments, the first thickness d1-3may be defined as the length of the first inorganic layer310in a direction perpendicular (e.g., substantially perpendicular) to the upper surface100US of the substrate100.

The first inorganic layer310may have a second thickness d2-3on the second surface S2-3of the lower layer LL-3. The second thickness d2-3may be defined as the length of the first inorganic layer310in a direction perpendicular (e.g., substantially perpendicular) to the second surface S2-3of the lower layer LL-3. For example, the second thickness d2-3may be defined as an average value of the thicknesses of the first inorganic layer310on the second surface S2-3of the lower layer LL-3.

In an embodiment, the first thickness d1-3may be greater than or equal to the second thickness d2-3. When the angle A-3between the first surface S1-3and the second surface S2-3of the lower layer LL-3is an acute angle and the first inorganic layer310is formed by CVD, gas forming the first inorganic layer310may be more suitably or sufficiently supplied to the first surface S1-3of the lower layer LL-3than the second surface S2-3of the lower layer LL-3. Therefore, the first thickness d1-3may be greater than or equal to the second thickness d2-3. In some embodiments, the first thickness d1-3may be less than the second thickness d2-3. In another embodiment, the first thickness d1-3may be greater than the second thickness d2-3. When the first inorganic layer310is formed by physical vapor deposition, the first thickness d1-3may be greater than the second thickness d2-3. In another embodiment, the first thickness d1-3may be greater than, less than, or equal to the second thickness d2-3. When the first inorganic layer310is formed by atomic layer deposition, the first thickness d1-3may be greater than, less than, or equal to the second thickness d2-3.

A ratio of the second thickness d2-3to the first thickness d1-3may be about 0.51 or more. For example, the step coverage may be about 0.51 or more. In some embodiments, the ratio of the second thickness d2-3to the first thickness d1-3may be about 0.76 or more. Therefore, the first inorganic layer310may suitably or sufficiently cover the pixel defining layer220, the spacer230, the pattern layer240, and the organic light-emitting diode OLED, and the reliability of the display device may be improved.

As described above, one or more embodiments may include a thin-film encapsulation layer including at least one inorganic layer and at least one organic layer. In this case, because a ratio of a second thickness to a first thickness of the at least one inorganic layer is about 0.51 or more, a defect rate of display devices may be substantially or significantly reduced. Therefore, the reliability of display devices may be improved.

It should be understood that embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments. While one or more embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the following claims, and equivalents thereof.