Stretchable display device

In the stretchable display device of the present disclosure, peeling and delamination of connection lines between adjacent circuits mounted on individual fixed substrates that might occur during stretching is reduced. According to one embodiment of the stretchable display device, the steepness of a slope in step in an insulating layer in contact with connection lines is reduced, which prevents delamination. A plurality of individual substrates are disposed on the lower substrate and located in the active area on the lower substrate. The modulus of elasticity of the individual substrates is significantly higher than the modulus of elasticity of the lower substrate. There is a first inorganic layer positioned on each of the plurality of individual substrates, the first inorganic layer having a sidewall surface extending upward from the first substrate. A organic layer is deposited overlying the first inorganic layer, including overlying the sidewall surface of the first inorganic layer. An electrical connection line is on the organic layer and not in contact with any part of the inorganic layer, providing the additional adhesion and thus preventing delamination of the electrical connection lines from the substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Korean Patent Application No. 10-2019-0078134 filed on Jun. 28, 2019 and the priority of Korean Patent Application No. 10-2020-0051688 filed on Apr. 28, 2020 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND

Technical Field

The present disclosure relates to a stretchable display device, and more particularly, to a stretchable display device which is improved in reliability by suppressing line opening in a connection line.

Description of the Related Art

Display devices used for a computer monitor, a TV, a mobile phone, etc., include an organic light-emitting display (OLED) that emits light by itself, a liquid-crystal display (LCD) that uses a separate light source, etc.

As the display devices have been increasingly used in diverse fields such as a computer monitor, a TV, and a personal mobile device, display devices having a large display area and a reduced volume and weight have been studied.

Recently, a stretchable display device in which a display part, lines, etc., are formed on a flexible substrate which can be stretched in a specific direction and deformed into various shapes has attracted attention as a next-generation display device.

BRIEF SUMMARY

An object to be achieved by the present disclosure is to provide a stretchable display device having higher reliability over long term use. In the stretchable display device of the present disclosure, peeling and delamination of connection lines between adjacent circuits mounted on individual fixed substrates that might occur during stretching of a lower, flexible substrate is reduced.

According to one embodiment of the stretchable display device, the steepness of a slope in step in an insulating layer in contact with connection lines is reduced, and, thus, peeling of the connection lines from the insulation layer can be reduced when the display device undergoes repeated stretching.

According to one embodiment, an undercut portion which may be formed in a substrate during manufacturing is filled with an overcoating layer, and, thus connection lines are protected from entering the undercut and instead transition from a horizontal surface at a first height to a horizontal surface at a second, higher height on a smooth, gradual slope, resulting in a breakage of connection lines being suppressed.

According to one embodiment damage to a thin film transistor, a capacitor, and connection lines disposed on a fixed substrate that is positioned on a flexible lower substrate can be reduced.

In one embodiment, contact points of connection lines are disposed on a protruding portion of a first substrate, and, thus, the area of the first substrate can be secured.

According to one embodiment of the present disclosure, a lower substrate has an active area and a non-active area adjacent to the active area, the lower substrate having a first modulus of elasticity. A plurality of individual substrates are disposed on the lower substrate and located in the active area on the lower substrate. In one embodiment, the modulus of elasticity of the individual substrates is significantly higher than the modulus of elasticity of the lower substrate. The individual substrates are spaced from each other. There is a first inorganic layer positioned on each of the plurality of individual substrates, the first inorganic layer having a sidewall surface extending upward from the first substrate. An organic layer is deposited overlying the first inorganic layer, including overlying the sidewall surface of the first inorganic layer. In some embodiments, the organic layer is in direct contact with the sidewall and top surfaces of the inorganic layer. In other embodiments, it is only in direct contact with the sidewall surface of the inorganic layer and not with the top surface. In other embodiments, it overlies the first inorganic layer and does not directly contact it and there are one or more layers between the inorganic layer and the organic layer.

The organic layer having a sidewall surface extending upward from the first substrate. There are a plurality of respective pixels disposed on the respective plurality of individual substrates on the organic layer. Each pixel has electrical components comprising the pixel, An electrically conductive connection line is disposed between components of the respective pixels on two adjacent individual substrates. In some embodiments, the connection line is directly on the organic layer.

In some embodiments, the sidewall surface of the first inorganic layer extends upward from the first substrate at a first angle relative to the upper surface of the first substrate and the sidewall surface of the organic layer extends upward from the first substrate at a second angle relative the upper surface of the first substrate. In some embodiments, first angle is within the range of 85° to 90° and the second angle is within the range of 65° to 85°.

In a practical application, the lower substrate has a first modulus of elasticity and each individual substrate has a second modulus of elasticity that is higher than the first modulus of elasticity.

In further practical applications, there is a second inorganic layer overlying the first inorganic layer, the second inorganic layer having a sidewall surface, the organic layer overlying the second inorganic layer, including overlying the sidewall of the second inorganic layer.

In some embodiments, a portion of the organic layer extends underneath a region of the first inorganic layer.

A method of manufacturing the display device as disclosed herein my include the steps of forming a plurality of individual substrates on a lower substrate; forming a connection support layer extending between adjacent individual substrates; forming a transistor on each of the plurality of individual substrates; depositing a first inorganic layer on each of the individual substrates, the inorganic having a sidewall surface extending upward from the individual substrate; depositing an organic layer overlying the individual substrates and the inorganic layer, including the sidewall of the inorganic layer and the lower substrate; patterning and etching the organic layer to remove it from lower substrate; depositing an electrically conductive connection layer overlying the connection support layer; and patterning and etching the electrically conductive connection layer to form a connection line extending between adjacent individual substrates.

In some embodiments, the step of depositing of the organic layer is carried out after the step of forming the connection support layer. In other embodiments, the steps of forming a plurality of individual substrates on a lower substrate and forming a connection support layer extending between adjacent individual substrates are carried out concurrently.

In a practical application, the connection support is created by etching the connection support layer and during its etching, an undercut is create below the top surface of the inorganic layer and the undercut is filled with the organic layer during the depositing of the organic layer. After the organic layer is deposited, a light emitting diode is placed on the organic layer on each of the first substrates.

Objects and benefits of the present disclosure are not limited to the above-mentioned benefits and the embodiments are not so limited to those stated herein and other benefits which are not mentioned above, can be clearly understood by those skilled in the art from the following descriptions.

According to the present disclosure, when a stretchable display device is stretched repeatedly, the peeling of connection lines is suppressed.

DETAILED DESCRIPTION

A size and a thickness of each component illustrated in the drawing are illustrated for convenience of description and ease of understanding, and the present disclosure is not limited to the size and the thickness of the component illustrated.

A stretchable display device may refer to a display device which can display images even it is bent or stretched. The stretchable display device may have higher flexibility than typical display devices. Thus, the stretchable display device can be freely deformed by a user's manipulation such as bending or stretching of the stretchable display device. For example, when the user seizes an end of the stretchable display device and pulls the stretchable display device, the stretchable display device can be stretched by force of the user. If the user places the stretchable display device on an uneven wall surface, the stretchable display device can be bent according to the shape of the wall surface. When the force applied by the user is removed, the stretchable display device can return to its original shape.

FIG.1is an exploded perspective view illustrating a stretchable display device according to an example embodiment of the present disclosure. Referring toFIG.1, a stretchable display device100includes a lower substrate110, a plurality of first substrates111, a plurality of connection supports120, a plurality of second substrates121, a COF (Chip on Film)130, a printed circuit board140, and an upper substrate US.FIG.1also shows a plurality of electrical connections lines180, which include lines181and182that are supported by and lie directly on top of the connection supports120, as described later herein. These lines181and182electrically connect the first substrates111to each other and also the second substrates121to each other and first substrates111, as also described later herein.

The lower substrate110serves to protect and support various components disposed in the stretchable display device100. The lower substrate110is a ductile substrate and may be formed of an insulating material which can be bent or stretched. For example, the lower substrate110may be formed of silicone rubber such as polydimethylsiloxane (PDMS) and an elastomer such as polyurethane (PU), and polytetrafluoroethylene (PTFE). Thus, the lower substrate110may have flexibility. However, the materials of the lower substrate110are not limited thereto.

The lower substrate110is a ductile substrate and can be reversibly expanded and contracted. Further, the lower substrate110may have an elastic modulus ranging from several MPa to several hundreds of MPa and may have a stretch failure of 100% or more. Herein, the stretch failure refers to a stretch rate at the time when an object being stretched is destroyed or cracked. The thickness of the lower substrate110may be from 10 μm to 1 mm, but is not limited thereto.

The lower substrate110may include an active area AA and a non-active area NA surrounding the active area AA.

The active area AA refers to an area of the stretchable display device100in which images are displayed. In the active area AA, a display element and various drive elements for driving the display element are disposed. The active area AA includes a plurality of pixels including a plurality of sub-pixels. The plurality of pixels are disposed in the active area AA and each includes a plurality of display elements called subpixels. Each of the plurality of sub-pixels may be connected to various lines. For example, each of the plurality of sub-pixels may be connected to various lines such as a gate line, a data line, a high-potential power line, a low-potential power line, a reference voltage line, etc.

The non-active area NA refers to an area adjacent to the active area AA. The non-active area NA is formed around the active area AA. In the non-active area NA, images are not displayed, and lines and circuits may be disposed in NA. For example, a plurality of pads may be disposed in the non-active area NA, and the pads may be connected respectively to the plurality of sub-pixels disposed in the active area AA.

On the lower substrate110, the plurality of first substrates111and the plurality of second substrates121are disposed. The plurality of first substrates111may be disposed in the active area AA of the lower substrate110, and the plurality of second substrates121may be disposed in the non-active area NA of the lower substrate110.FIG.1illustrates that the plurality of second substrates121in the non-active area NA is disposed on the upper side and left side of the active area AA. However, the present disclosure is not limited thereto. The plurality of second substrates121may be disposed in any region of the non-active area NA.

The plurality of first substrates111and the plurality of second substrates121are rigid substrates and independently spaced apart from each other on the lower substrate110. The plurality of first substrates111and the plurality of second substrates121may be more rigid than the lower substrate110. That is, the lower substrate110may be more ductile than the plurality of first substrates111and the plurality of second substrates121. Also, the plurality of first substrates111and the plurality of second substrates121may be more rigid than the lower substrate110.

The plurality of first substrates111and the plurality of second substrates121as a plurality of rigid substrates may be formed of a plastic material having flexibility. The plurality of first substrates111and the plurality of second substrates121may be formed of, for example, polyimide (PI), polyacrylate, polyacetate, etc. In this case, the plurality of first substrates111may be formed of the same material as the plurality of second substrates121, but is not limited thereto. The first substrates111may also be formed of a different material from the plurality of second substrates121.

The plurality of first substrates111and the plurality of second substrates121may have a higher modulus than the lower substrate110. Herein, the modulus refers to an elastic modulus that is the ratio of the stress applied to a substrate to a change caused by the stress. If the modulus is relatively high, the rigidity may be relatively high. Therefore, the plurality of first substrates111and the plurality of second substrates121may be a plurality of rigid substrates having a higher rigidity than the lower substrate110. The modulus of the plurality of first substrates111and the plurality of second substrates121may be 1000 times or more than that of the lower substrate110, but is not limited thereto.

In some example embodiments, the lower substrate110may be defined as including a plurality of first lower patterns and a second lower pattern. The plurality of first lower patterns may be disposed in a region of the lower substrate110which overlaps the plurality of first substrates111and the plurality of second substrates121. Also, the second lower pattern may be disposed in a region except the region where the plurality of first substrates111and the plurality of second substrates121are disposed. Otherwise, the second lower pattern may be disposed in the entire region of the stretchable display device100.

In this case, the plurality of first lower patterns may have a higher modulus than the second lower pattern. For example, the plurality of first lower patterns may be formed of the same material as the plurality of first substrates111. Also, the second lower pattern may be formed of a material having a lower modulus than the plurality of first substrates111.

The COF130refers to a film formed by placing various components on a ductile base film131and is configured to supply signals to the plurality of sub-pixels in the active area AA. The COF130may be bonded to the plurality of pads of the plurality of second substrates121disposed in the non-active area NA. The COF130may supply power voltage, data voltage, gate voltage, etc., through the pads to the respective sub-pixels disposed in the active area AA. The COF130may include the base film131and a drive IC132and may further include various components thereon.

The base film131serves to support the drive IC132of the COF130. The base film131may be formed of an insulating material. For example, the base film131may be formed of an insulating material having flexibility.

The drive IC132is configured to process data for displaying an image and a drive signal for processing the data.FIG.1illustrates that the drive IC132is mounted by a COF method, but is not limited thereto. The drive IC132may also be mounted by a Chip On Glass (COG) method or a Tape Carrier Package (TCP) method.

FIG.1illustrates that a second substrate121is disposed in the non-active area NA on the upper side of the active area AA so as to correspond to first substrates111in a row disposed in the active area AA. Also,FIG.1illustrates that a COF130is disposed on the second substrate121. However, the present disclosure is not limited thereto. That is, a second substrate121and a COF130may be disposed so as to correspond to first substrates111in a plurality of rows.

In the printed circuit board140, a control unit such as an IC chip, a circuit, etc., may be disposed. Further, in the printed circuit board140, a memory, a processor, etc., may also be disposed. The printed circuit board140is configured to transfer a signal for driving the display elements from the control unit to the display elements. AlthoughFIG.1illustrates that three the printed circuit board140are used, the number of printed circuit boards140is not limited thereto.

Hereafter, the stretchable display device100according to an example embodiment of the present disclosure will be described in more detail with reference toFIG.2andFIG.3.

FIG.2is an enlarged plan view illustrating a stretchable display device according to an example embodiment of the present disclosure.FIG.3is a schematic cross-sectional view illustrating a sub-pixel ofFIG.2.FIG.1will also be referred to for convenience of explanation.

Referring toFIG.1andFIG.2, the plurality of first substrates111is disposed on the lower substrate110in the active area AA. The plurality of first substrates111is disposed and spaced apart from each other on the lower substrate110. For example, the plurality of first substrates111may be disposed in a matrix form on the lower substrate110as shown inFIG.1andFIG.2, but is not limited thereto.

Referring toFIG.1andFIG.2, a plurality of sub-pixels SPX constituting a plurality of pixels PX may be disposed in the plurality of first substrates111. Further, gate drivers GD may be mounted respectively on second substrates121located on the left side of the active area AA among the plurality of second substrates121. The gate drivers GD may be formed on the second substrates121by a Gate In Panel (GIP) method when various components on the first substrates111are fabricated. Thus, various circuit components, such as various transistors, capacitors, and lines, constituting the gate drivers GD may be disposed on the plurality of second substrates121. However, the present disclosure is not limited thereto. The gate drivers GD may be mounted by a COF method. Otherwise, the plurality of second substrates121may be disposed in the non-active area NA on the right side of the active area AA. Also, the gate drivers GD may be mounted on the plurality of second substrates121located on the right side of the active area AA.

Referring toFIG.1, the plurality of second substrates121may be larger in size than the plurality of first substrates111. Specifically, each of the plurality of second substrates121may be larger than each of the plurality of first substrates111. As described above, the gate drivers GD are disposed on the plurality of second substrates121, respectively. For example, a single stage of the gate driver GD may be disposed on each of the plurality of second substrates121. Therefore, the size of various circuit components constituting a single stage of the gate driver GD is relatively larger than the first substrate111in which pixels PX are disposed. Accordingly, each of the plurality of second substrates121may have a larger size than each of the plurality of first substrates111.

Referring toFIG.1andFIG.2, a plurality of connection supports120may be disposed between the plurality of first substrates111or between the plurality of second substrates121. Otherwise, the plurality of connection supports120may be disposed between the plurality of first substrates111and the plurality of second substrates121. The plurality of connection supports120serves to connect the first substrates111adjacent to each other, the second substrates121adjacent to each other, or the first substrates111and the second substrates121. Thus, the plurality of connection supports120can also be referred to as connection substrates. The plurality of connection supports120may be formed of the same material as the first substrates111or the second substrates121. They can be and simultaneously formed as one body with the first substrates111or the second substrates121, but they are not limited to being formed in this manner. For example, connection supports120can be formed on the lower substrate110after the first substrates111and second substrates121are placed thereon, as explained later herein.

Referring toFIG.2, a plurality of electrical connections lines181and182are provided that electrically connect the first substrates111to each other and also the second substrates121to each other and first substrates111. As shown inFIG.1, these lines overlie directly on top of the connection supports120, therefore, the connection supports120cannot be seen inFIG.2in those locations where the connection lines181and182are present.

Referring toFIG.2, the connection supports120are shown a number of places prior to the connection lines181and182being formed over them. As can be seen, the plurality of connection supports120is wavy, exactly matching the shape of the respective connection lines they support. For example, as shown inFIG.2, the plurality of connection supports120may have a sine wave shape. However, the shape of the plurality of connection supports120is not limited thereto. For example, the plurality of connection supports120may be extended in a zigzag shape, or the plurality of diamond-shaped connection supports120may be extended and connected to each other at their vertices. The number and shape of the plurality of connection supports120shown inFIG.2is just an example. The number and shape of the plurality of connection supports120may vary depending on the design. In a preferred embodiment, the shape of the connection supports will match the shape of the connection lines181and182that they support.

Referring toFIG.3, a plurality of inorganic insulating layers is formed on the plurality of first substrates111. For example, the plurality of inorganic insulating layers may include a buffer layer112, a gate insulating layer113, and an interlayer insulating layer114, but is not limited thereto. Various inorganic insulating layers may be further disposed on the plurality of first substrates111. In some embodiments one or more of the buffer layer112, the gate insulating layer113, and the interlayer insulating layer114may be omitted.

Referring toFIG.3, the buffer layer112is disposed on the plurality of first substrates111. The buffer layer112is formed on the plurality of first substrates111to protect various components of the stretchable display device100against permeation of moisture (H2O), oxygen (O2), and the like from the outside of the lower substrate110and the plurality of first substrates111. The buffer layer112may be formed of an insulating material. For example, the buffer layer112may be formed as one or more inorganic layers of silicon nitride (SiNx), silicon oxide (SiOx), silicon oxynitride (SiON), etc. However, the buffer layer112may be omitted depending on the structure or characteristics of the stretchable display device100.

In one embodiment, the substrates111and121, and all the layers thereon, are each formed in a separate process from the formation of lower substrate110. After the substrates111and112are formed, they are placed at selected locations on lower substrate110, as shown inFIG.1.

As described above, the buffer layer112may be formed of an inorganic material. Thus, the buffer layer112may be easily damaged, such as cracked, while the stretchable display device100is being stretched. Therefore, the buffer layer112is preferably not formed between the plurality of first substrates111and the plurality of second substrates121. Rather, the buffer layer112may be formed and patterned only on the plurality of first substrates111and the plurality of second substrates121. In the stretchable display device100according to an example embodiment of the present disclosure, the buffer layer112is formed only in a region respective first substrates111and second substrates121which are rigid substrates. Thus, it is possible to suppress damage to the buffer layer112even when the stretchable display device100is deformed, such as bent or stretched since this buffer layer112is fully on the rigid substrates111and112.

Referring toFIG.3, a transistor150including a gate electrode151, an active layer152, a source electrode153, and a drain electrode154is formed on the buffer layer112.

Referring toFIG.3, first, the active layer152is disposed on the buffer layer112. For example, the active layer152may be formed of an oxide semiconductor or may be formed of amorphous silicon (a-Si), polycrystalline silicon (poly-Si), an organic semiconductor, or the like.

The gate insulating layer113is disposed on the active layer152. The gate insulating layer113serves as a layer for electrically insulating the gate electrode151and the active layer152and may be formed of an insulating material. For example, the gate insulating layer113may be formed as one or more inorganic layers of silicon nitride (SiNx) or silicon oxide (SiOx), but is not limited thereto.

The gate electrode151is disposed on the buffer layer112. The gate electrode151is disposed to overlap the active layer152. The gate electrode151may be formed of any one of various metal materials, for example, molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu). Otherwise, the gate electrode151may be formed of an alloy of two or more of them or may be formed as a multi-layer thereof, but is not limited thereto.

The interlayer insulating layer114is disposed on the gate electrode151. The interlayer insulating layer114serves to insulate the gate electrode151from the source electrode153and the drain electrode154and may be formed of an inorganic material like the buffer layer112. For example, the interlayer insulating layer114may be formed as one or more inorganic layers of silicon nitride (SiNx) or silicon oxide (SiOx), but is not limited thereto.

The source electrode153and the drain electrode154in contact with the active layer152are disposed on the interlayer insulating layer114. The source electrode153and the drain electrode154are disposed and spaced apart from each other on the same layer. The source electrode153and the drain electrode154in contact with the active layer152may be electrically connected to the active layer152. The source electrode153and the drain electrode154may be formed of any one of various metal materials, for example, molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu). Otherwise, the source electrode153and the drain electrode154may be formed of an alloy of two or more of them or may be formed as a multi-layer thereof, but is not limited thereto.

Further, the gate insulating layer113and the interlayer insulating layer114may be patterned and formed only in a region overlapping the plurality of first substrates111. The gate insulating layer113and the interlayer insulating layer114may also be formed of an inorganic material like the buffer layer112. Thus, the gate insulating layer113and the interlayer insulating layer114may be easily damaged, such as cracked, while the stretchable display device100is stretched. Therefore, the gate insulating layer113and the interlayer insulating layer114may not be formed between the plurality of first substrates111. The gate insulating layer113and the interlayer insulating layer114may be patterned into the plurality of first substrates111and formed only on the plurality of first substrates111.

For convenience of explanation,FIG.3illustrates only a driving transistor among various transistors which can be included in the stretchable display device100. However, a switching transistor, a capacitor, etc., can also be included in the display device and positioned on the same first substrate111with the pixel. Further, in the present disclosure, the transistor150has been described as having a coplanar structure, but various transistors having a staggered structure, or the like may also be used.

Referring toFIG.3, a plurality of pads170is disposed on the interlayer insulating layer114. Specifically, a gate pad171is disposed on the interlayer insulating layer114among the plurality of pads170. The gate pad171serves to transfer gate signals to the plurality of sub-pixels SPX. A gate signal may be transferred from the gate pad171to the gate electrode151through a gate line formed on the first substrate111. The gate pad171may be formed of the same material as the source electrode153and the drain electrode154, but is not limited thereto.

Referring toFIG.3, a data pad172is disposed on the interlayer insulating layer114among the plurality of pads170. The data pad172serves to transfer data signals to the plurality of sub-pixels SPX. A data signal may be transferred from the data pad172to the source electrode153or the drain electrode154through a data line formed on the first substrate111. The data pad172may be formed of the same material as the source electrode153and the drain electrode154, but is not limited thereto.

Referring toFIG.3, an overcoating layer115is formed on the transistor150and the interlayer insulating layer114. The overcoating layer115serves as a planarizing layer over the transistor150, thus providing a flat upper surface over the transistor150. The overcoating layer115may be formed as one or more layers and formed of an organic material. Thus, the overcoating layer115may also be referred to as an organic insulating layer or an organic planarizing layer. For example, the overcoating layer115may be formed of an acryl-based organic material, but is not limited thereto. While in a preferred embodiment, overcoating layer115is a single layer of organic material deposited as in single step as one complete layer, in some embodiments, layer115can also be an comprised of one or more layers that are deposited sequentially. For example overcoating layer115can be deposited as two or more sequential layers, both of which are organic or can be deposited having some layers that are inorganic with an organic layer being deposited first in contact with the buffer layer112and then further layers, some organic and some inorganic overlaying the first deposited organic layer and all the layers together forming the overcoating layer115.

Referring toFIG.3, the overcoating layer115is disposed on the plurality of first substrates111to cover upper surfaces and side surfaces of the buffer layer112, the gate insulating layer113, and the interlayer insulating layer114. Also, together with the plurality of first substrates111, the overcoating layer115surrounds the buffer layer112, the gate insulating layer113, and the interlayer insulating layer114. Specifically, the overcoating layer115may be disposed to cover an upper surface and a side surface of the interlayer insulating layer114, a side surface of the gate insulating layer113, a side surface of the buffer layer112, and a part of upper surfaces of the plurality of first substrates111. Thus, the overcoating layer115can compensate for a steep, vertical step on the side surfaces of the buffer layer112, the gate insulating layer113, and the interlayer insulating layer114. Also, the overcoating layer115can enhance the adhesion strength between the overcoating layer115and connection lines180disposed on a side surface of the overcoating layer115. Namely, the overcoating layer can provide a stronger adhesion to connection lines180than would be provided by the side surfaces of layers112,113and114.

Referring toFIG.3, an incline angle θ2of the side surface of the overcoating layer115may be lower than an incline angle θ1of the side surfaces of the buffer layer112, the gate insulating layer113, and the interlayer insulating layer114. In some embodiments, the angle θ1can about 90°. On the other hand, the angle θ2can be in the range of 80° to 70°, or in some cases can be 60°. For example, the side surface of the overcoating layer115may have a lower incline angle than the side surface of the interlayer insulating layer114, the side surface of the gate insulating layer113, and the side surface of the buffer layer112. Thus, the connection lines180in contact with the side surface of the overcoating layer115are disposed with a low incline angle. Therefore, when the stretchable display device100is stretched, stress generated on the connection lines180can be reduced. Also, it is possible to suppress cracks in the connection lines180or peeling of the connection lines180from the side surface of the layers on the substrate111because the overcoating layer115is present. This suppression of peeling is provided by at least two factors, first, the overcoating layer has a stronger adhesion to the connection lines180than the layers112,113and114and second, because the angle θ2is less than the angle θ1. The layers112,113and114constitute first, second and third inorganic layers on the substrate111and the overcoating layer115can be an organic layer that is over and in contact with each of these layers.

In some embodiments, a passivation layer may be formed between the transistor150and the overcoating layer115. That is, the passivation layer covering the transistor150may be formed to protect the transistor150against permeation of moisture, oxygen, and the like. The passivation layer may be formed of an inorganic material and formed as one or more layers, but is not limited thereto. The passivation layer may be considered a sublayer of layer115in some embodiments.

Referring toFIG.3, a common line CL is disposed on the gate insulating layer113. The common line CL serves to apply a common voltage to the plurality of sub-pixels SPX. The common line CL may be formed of the same material as the gate electrode151of the transistor150, but is not limited thereto.

Referring toFIG.2andFIG.3, the connection lines180refer to lines that electrically connect pads on the plurality of first substrates111or the plurality of second substrates121. The connection lines180are disposed on the first substrate111and the plurality of connection supports120.

The connection lines180include a first connection line181and a second connection line182. The first connection line181and the second connection line182are disposed between the plurality of first substrates111. Specifically, the first connection line181refers to a line extended in an X-axis direction between the plurality of first substrates111among the connection lines180. The second connection line182refers to a line extended in a Y-axis direction between the plurality of first substrates111among the connection lines180. The X-axis direction and Y-axis direction are positioned in a plane parallel to the display surface and are referenced to the typical viewing orientation.

The connection lines180may be formed of a metal material such as copper (Cu), aluminum (Al), titanium (Ti), or molybdenum (Mo). The connection lines180may have a metal-laminated structure of copper/molybdenum-titanium (Cu/MoTi), titanium/aluminum/titanium (Ti/Al/Ti), or the like, but are not limited thereto.

In a general organic light-emitting display device, various lines such as a plurality of gate lines and a plurality of data lines are extended in a straight line and disposed between a plurality of sub-pixels. Also, a single signal line is connected to a plurality of sub-pixels. Therefore, in the general organic light-emitting display device, various lines such as a gate line, a data line, a high-potential power line, and a reference voltage line, are continuously extended on a substrate from one side to the other side of the organic light-emitting display device.

However, in the stretchable display device100according to an example embodiment of the present disclosure, various lines, such as a gate line, a data line, a high-potential power line, and a reference voltage line, which are formed in a straight line and have been used in the general organic light-emitting display device are disposed only on the plurality of first substrates111and the plurality of second substrates121. That is, in the stretchable display device100according to an example embodiment of the present disclosure, various lines formed in a straight line are disposed only on the plurality of first substrates111and the plurality of second substrates121.

In the display device100according to an example embodiment of the present disclosure, pads on two adjacent first substrates111or second substrates121may be connected by the connection lines180to connect discontinuous lines on the first substrates111or second substrates121. That is, the connection lines180electrically connect pads on two adjacent first substrates111, two adjacent second substrates121, and a first substrate111and a second substrate121adjacent to each other. Therefore, the stretchable display device100according to an example embodiment of the present disclosure may include the plurality of connection lines180. The plurality of connection lines180serves to electrically connect various lines, such as a gate line, a data line, a high-potential power line, and a reference voltage line, between the plurality of first substrates111, between the plurality of second substrates121, and between the plurality of first substrates111and the plurality of second substrates121. For example, a gate line may be disposed on the plurality of first substrates111disposed adjacent to each other in the X-axis direction and the gate pads171may be disposed on both ends of the gate line. In this case, a plurality of gate pads171on the plurality of first substrates111disposed adjacent to each other in the X-axis direction may be connected to each other by the first connection line181serving as a gate line. Therefore, a gate line disposed on the plurality of first substrates111and the first connection line181disposed on the substrate121may serve as a single gate line. Further, lines, for example, a light signal line, a low-potential power line, a high-potential power line, are extended in the X-axis direction among all the various lines which can be included in the stretchable display device100. These lines may also be electrically connected by the first connection line181as described above.

Referring toFIG.2andFIG.3, the first connection line181may connect pads on two first substrates111disposed parallel to each other among pads on a plurality of first substrates111disposed adjacent to each other in the X-axis direction. The first connection line181may serve as a gate line, a light signal line, a high-potential power line, or a low-potential power line, but is not limited thereto. For example, the first connection line181may serve as a gate line and electrically connect gate pads171on two first substrates111disposed parallel to each other in the X-axis direction. Therefore, as described above, the gate pads171on the plurality of first substrates111disposed in the X-axis direction may be connected by the first connection line181serving as a gate line. A gate signal may be transferred to the gate pads171.

Referring toFIG.2, the second connection line182may connect pads on two first substrates111disposed parallel to each other among pads on a plurality of first substrates111disposed adjacent to each other in the Y-axis direction. The second connection line182may serve as a data line, a high-potential power line, a low-potential power line, or a reference voltage line, but is not limited thereto. For example, the second connection line182may serve as a data line and electrically connect data lines DL on two first substrates111disposed parallel to each other in the Y-axis direction. Therefore, as described above, the data lines DL on the plurality of first substrates111disposed in the Y-axis direction may be connected by a plurality of second connection lines182serving as data lines. A data signal may be transferred to the data lines DL.

Referring toFIG.1, the connection lines180may further include a line that connect pads on the plurality of first substrates111and the plurality of second substrates121. The line may connect pads on two second substrates121disposed in parallel to each other among the plurality of second substrates121disposed adjacent to each other in the Y-axis direction.

The first connection line181is in contact with an upper surface and a side surface of the overcoating layer115disposed on the first substrate111and may be extended to an upper surface of the second substrate120. Also, the second connection line182is in contact with the upper surface and the side surface of the overcoating layer115disposed on the first substrate111and may be extended to the upper surface of the second substrate120. The layout of the first connection line181and the second connection line182and the effect thereof will be described in detail.

Referring toFIG.3, a bank116is formed on a first connection pad191, a second connection pad192, the connection lines180, and the overcoating layer115. The bank116separates adjacent sub-pixels SPX from each other.

The bank116is disposed to cover a part of the second connection line182and first connection pad191adjacent thereto or at least a part of the first connection line181and second connection pad192. The bank116may be formed of an insulating material. Further, the bank116may contain a black material. Since the bank116contains a black material, the bank116serves to hide lines which can be seen through the active area AA. The bank116may be formed of, for example, a transparent carbon-based mixture. Specifically, the bank116may contain carbon black, but is not limited thereto. The bank116may also be formed of a transparent insulating material.

Referring toFIG.3, an LED160is disposed on the first connection pad191and the second connection pad192. The LED160includes an n-type layer161, an active layer162, a p-type layer163, an n-electrode164, and a p-electrode165. The LED160of the display device100according to an example embodiment of the present disclosure has a flip-chip structure in which the n-electrode164and the p-electrode165are formed on its one side surface.

The n-type layer161may be formed by injecting n-type impurities into gallium nitride (GaN) having excellent crystallinity. The n-type layer161may be disposed on a separate base substrate which is formed of a light-emitting material.

The active layer162is disposed on the n-type layer161. The active layer162is a light-emitting layer in the LED160and may be formed of a nitride semiconductor, for example, indium gallium nitride (InGaN). The p-type layer163is disposed on the active layer162. The p-type layer163may be formed by injecting p-type impurities into gallium nitride (GaN).

The LED160according to an example embodiment of the present disclosure is manufactured by sequentially laminating the n-type layer161, the active layer162, and the p-type layer163, etching a predetermined region, and forming the n-electrode164and the p-electrode165. In this case, the predetermined region is a space to separate the n-electrode164and the p-electrode165and is etched to expose a part of the n-type layer161. In other words, a surface of the LED160on which the n-electrode164and the p-electrode165are to be disposed may not be flat but may have different levels of height.

The n-electrode164is disposed on the etched region, i.e., on the n-type layer161which is exposed by etching. The n-electrode164may be formed of a conductive material. Meanwhile, the p-electrode165is disposed on the non-etched region, i.e., on the p-type layer163. The p-electrode165may be formed of a conductive material. For example, the p-electrode165may be formed of the same material as the n-electrode164.

An adhesive layer AD is disposed on upper surfaces of the first connection pad191and the second connection pad192and between the first connection pad191and the second connection pad192. Thus, the LED160can be bonded onto the first connection pad191and the second connection pad192. In this case, the n-electrode164may be disposed on the second connection pad192and the p-electrode165may be disposed on the first connection pad191.

The adhesive layer AD may be a conductive adhesive layer formed by dispersing conductive balls in an insulating base member. Thus, when heat or pressure is applied to the adhesive layer AD, the conductive balls are electrically connected in a region applied with heat or pressure. Therefore, the pressed region may have conductive properties, and a non-pressed region may have insulating properties. For example, the n-electrode164is electrically connected to the second connection line182through the adhesive layer AD, and the p-electrode165is electrically connected to the first connection line181through the adhesive layer AD. That is, the adhesive layer AD may be coated on the first connection pad191and the second connection pad192by inkjet or other methods. Then, the LED160may be transferred onto the adhesive layer AD. Then, the LED160may be pressed and heated to electrically connect the first connection pad191to the p-electrode165and the second connection pad192to the n-electrode164. The adhesive layer AD except a part of the adhesive layer AD between the n-electrode164and the second connection pad192and a part of the adhesive layer AD between the p-electrode165and the first connection pad191has insulating properties. Meanwhile, the adhesive layer AD may be separated, and each may be disposed on each of the first connection pad191and the second connection pad192.

As such, the display device100according to an example embodiment of the present disclosure has a structure in which the LED160is disposed on the lower substrate110in which the transistor150is disposed. Thus, when the display device100is turned on, different levels of voltage are applied to the first connection pad191and the second connection pad192, respectively. The voltages are transferred to the n-electrode164and the p-electrode165so that the LED160can emit light.

Referring toFIG.3, an upper substrate US is disposed on the bank116, the LED160, and the lower substrate110.

The upper substrate US serves to support various components disposed under the upper substrate US. Specifically, the upper substrate US may be formed by coating and hardening a material of the upper substrate US on the lower substrate110and the first substrate111. Further, the upper substrate US may be disposed to be in contact with the lower substrate110, the first substrate111, the second substrate120, and the connection lines180.

The upper substrate US is a ductile or flexible substrate and may be formed of an insulating material which can be bent or stretched. The upper substrate US is a ductile substrate and can be reversibly expanded and contracted. Further, the upper substrate US may have an elastic modulus ranging from several MPa to several hundreds of MPa and may have a stretch failure of 100% or more. The thickness of the upper substrate US may be from 10 μm to 1 mm, but is not limited thereto.

The upper substrate US may be formed of the same material as the lower substrate110. For example, the upper substrate US may be formed of silicone rubber such as polydimethylsiloxane (PDMS) and an elastomer such as polyurethane (PU). Thus, the upper substrate US may have flexibility. However, the materials of the upper substrate US are not limited thereto.

Meanwhile, although not illustrated inFIG.3, a polarizing layer may also be disposed on the upper substrate US. The polarizing layer polarizes light incident from the outside of the stretchable display device100and suppresses reflection of external light. Further, instead of the polarizing layer, another optical film or the like may be disposed on the upper substrate US.

In a conventional stretchable display device, an overcoating layer formed of an organic insulating material does not cover side surfaces of a plurality of inorganic insulating layers including a buffer layer, a gate insulating layer, and an interlayer insulating layer. Instead, the overcoating layer is disposed on the plurality of inorganic insulating layers. Thus, connection lines are disposed to be in contact with the side surfaces of the plurality of inorganic insulating layers. However, when a patterning process, i.e., an etching process, is performed to the plurality of inorganic insulating layers, a step may be formed on the side surfaces of the plurality of inorganic insulating layers. That is, the side surfaces of the plurality of inorganic insulating layers have a very high incline angle after the etching process. Therefore, if the connection lines are formed directly on the side surfaces of the plurality of inorganic insulating layers, line opening may occur in the connection lines.

In the stretchable display device100according to an example embodiment of the present disclosure, the overcoating layer115is disposed to cover the side surfaces of the plurality of inorganic insulating layers, such as the buffer layer112, the gate insulating layer113, and the interlayer insulating layer114, between the first substrate111and the overcoating layer115. Thus, the overcoating layer115can compensate for a step on the side surfaces of the buffer layer112, the gate insulating layer113, and the interlayer insulating layer114. That is, the overcoating layer115is disposed to cover the upper surfaces and the side surfaces of the buffer layer112, the gate insulating layer113, and the interlayer insulating layer114. Also, the incline angle θ2of the side surface of the overcoating layer115may be lower than the incline angle θ1of the side surfaces of the buffer layer112, the gate insulating layer113, and the interlayer insulating layer114. That is, the side surface of the overcoating layer115may have a lower incline angle than the side surface of the interlayer insulating layer114, the side surface of the gate insulating layer113, and the side surface of the buffer layer112. Thus, the connection lines180in contact with the side surface of the overcoating layer115are disposed with a low incline angle. Therefore, when the connection lines180are formed, the occurrence of cracks in the connection lines180can be suppressed. Also, when the stretchable display device100is stretched, stress generated on the connection lines180can be reduced. Further, it is possible to suppress cracks in the connection lines180or peeling of the connection lines180from the side surface of the overcoating layer115.

Meanwhile, in the stretchable display device100according to an example embodiment of the present disclosure, the connection lines180may have the same shape as the second substrate120and thus may have a sine wave shape. Therefore, a resistance of the connection lines180may increase compared to the case where the connection lines180have a straight line shape. Thus, copper (Cu) having low resistance among various metal materials which can be used for lines may be used for the connection lines180to reduce a resistance of the connection lines180. However, when Cu or other low-resistance metal materials are formed on an inorganic insulating layer, there may be a problem with adhesion strength between the metal materials and the inorganic insulating layer. That is, Cu or other low-resistance metal materials have small adhesion strength with respect to the inorganic insulating layer. Thus, if the connection lines180are disposed to be in contact with the side surface of the plurality of inorganic insulating layers such as the buffer layer112, the gate insulating layer113, and the interlayer insulating layer114, the connection lines180may peel off from the side surface of the buffer layer112, the gate insulating layer113, and the interlayer insulating layer114when the stretchable display device100is stretched. Therefore, the reliability of the stretchable display device100may be degraded.

Therefore, in the stretchable display device100according to an example embodiment of the present disclosure, the overcoating layer115is disposed to cover the side surfaces of the buffer layer112, the gate insulating layer113, and the interlayer insulating layer114. Thus, when the stretchable display device100is stretched repeatedly, it is possible to suppress peeling of the connection lines180from the overcoating layer115and the side surfaces of the plurality of inorganic insulating layers. More specifically, the connection lines180formed of Cu or other low-resistance metal materials are disposed on the upper surface and the side surface of the overcoating layer115formed of an organic insulating material. Thus, the adhesion strength of lower parts of the connection lines180can be enhanced. Therefore, in the stretchable display device100according to an example embodiment of the present disclosure, the overcoating layer115is disposed to cover the side surfaces of the plurality of inorganic insulating layers, such as the buffer layer112, the gate insulating layer113, and the interlayer insulating layer114, on the first substrate111. Thus, when the stretchable display device100is stretched repeatedly, it is possible to suppress peeling of the connection lines180from the overcoating layer115. Therefore, the reliability of the stretchable display device100can be improved.

Further, in the stretchable display device100according to an example embodiment of the present disclosure, the overcoating layer115is disposed on the plurality of inorganic insulating layers, such as the buffer layer112, the gate insulating layer113, and the interlayer insulating layer114, and the transistor150. Thus, when the LED160is transferred, it is possible to protect components disposed under the overcoating layer115. When the LED160is disposed on the stretchable display device100, the LED160may be pressed from above the stretchable display device100. In this case, the transistor150, various lines, and the connection lines180disposed under the LED160might be damaged by pressure if not protected. Therefore, the overcoating layer115is disposed on the buffer layer112, the gate insulating layer113, the interlayer insulating layer114, and the transistor150. Accordingly, when the LED160is transferred, stress caused by pressing on the transistor150can be reduced. Thus, damage to the transistor150, various lines, the connection lines180, and the like, disposed under the overcoating layer115can be reduced.

The overcoating layer115can also be somewhat ductile. It can have a modulus of elasticity that is between that of the connection support120and the inorganic layer114. It has slightly more ability to stretch than the glass that makes up layers112,113and114, which also aids to reduce the stress and peeling of the connection lines180when the display is stretched. The overcoating layer115can therefore as a type of buffer layer between the connection lines180and their connection to the first substrate111and second substrate121, accommodating some of the movement and stretch of the connection lines180as the display is stretched.

One acceptable method of making the display device100will now be described. As previously stated, the lower substrate110is a substrate for supporting and protecting various components of the stretchable display device100. The lower substrate110, which is a flexible substrate, may be made of a bendable or stretchable insulating material. For example, the lower substrate110may be made of silicon rubber such as polyimethylsiloxane (PDMS) or an elastomer such as polyurethane (PU), so it may have flexibility. The material of the lower substrate110, however, is not limited thereto. The lower substrate110, which is a flexible substrate, may reversibly expand and contract. The lower substrate110may have an elastic modulus of several to hundreds of MPa and a tensile fracture rate of 100% or more. The elastic modulus may be referred to herein either as the elastic modulus or in some instances, as the modulus. The thickness of the lower substrate110may be 10 μm to 1 mm, but is not limited thereto. The first substrates111and second substrates121are made separately from the lower substrate110. In one embodiment, though not required in all embodiments, all layers on the substrate111, are formed in full, having layer115and all parts of the LED160present. In such embodiments, they also contain second connection pad192and all other connection pads, such as171and172. They do not contain connection lines180as formed.

In another embodiment, the overcoating layer115is not present on the individual substrates111separately formed and it is deposited overlying the entire substrate110after the connection support120is deposited and formed. These substrates111and121are rigid substrates and their properties and relationship to the lower substrate are described in more detail in pending application U.S. application Ser. No. 16/590,083, filed on Oct. 1, 2019 and having the same assignee as the present application.

In one embodiment, after the rigid substrates111and121, as fully formed substrates as described, are placed on the lower substrate110. After this a connection layer material can be deposited between the substrates111and121. Alternatively, the connection layer material can be blanket deposited on the entire lower substrate, overlying each of the substrates111and121that have been previously placed on the lower substrate110. After this, an electrically conductive layer is blanket deposited on the exposed surfaces of the entire lower substrate, overlying each of the substrates111and121and the connection layer120. The electrically conductive layer is then patterned and etched to form the connection lines181and182. The same pattern that used to etch the connection lines181and182will then be used to etch the connection layer, which will result in forming the connection support120have the same shape and exactly under the connection lines181and182. One technique to accomplish this is to use an etch chemistry that will etch both layers at the same time, namely, the conductive layer comprising the lines181and182and connection layer that comprises the connection support120. In this embodiment, the etch chemistry selected will be one that does not etch the material that is exposed as the upper surface first and second substrates111and121.

A different technique that can be used is to etch the conductive layer to form the connection lines181and182with an etch chemistry that is selective to etch them, but will not etch other exposed areas on the display100. After this, using the lines181and182as the mask, the support layer is etched to form the connection supports120to have the very same shape as the lines181and182.

The connection layer can be made of any acceptable material that will be used for the connection supports120. One acceptable material is polyimide, also referred to as PI. PI is an organic material. It can take many forms and can be constructed to be somewhat flexible. In one embodiment, though not required in all embodiments, the polyimide that makes up the connection supports120can be constructed to have a modulus of elasticity that greater than that of the lower substrate110, but less than that of silicon nitride or silicon oxide that comprise layers112,113and114. It can therefore be slightly stretched, more than the glass layer of silicon nitride or silicon dioxide that will comprise layers112,113and114. Thus, it can act as intermediate layer of flexibility, having a modulus of elasticity that is between that of the lower substrate110and first substrate111. It can also have a modulus of elasticity that is between that of the lower substrate110and the overcoating layer115.

Since the connection supports120are made of polyimide, they can be etched by a different etch chemistry than the layers that make up the first substrate111and second substrate121. In addition, it is more flexible and has a softer upper surface than the inorganic glass layers112,113and114since it is comprised of PI.

The connection lines180therefore are in contact with and rest on organic material as they extend from one first substrate111to the adjacent first substrate111. Further, the flexibility, as measured by the modulus of elasticity, will be less than that of the inorganic layer112. In a preferred embodiment, the modulus of elasticity will be gradual change from one material to another on which it rests. The connection lines180are positioned on the organic layer120between the first substrates111that have a first selected modulus of elasticity, then, when they are over first substrate111, they are positioned on overcoating layer115that has a second selected modulus of elasticity that is greater than that of connection support120and less than that of the pads171and172that are on the layer114.

FIG.4Ais an enlarged cross-sectional view illustrating a stretchable display device according to another example embodiment of the present disclosure. A stretchable display device400shown inFIG.4Ais substantially the same as the stretchable display device100shown inFIG.1throughFIG.3except a plurality of first substrates411, a plurality of connection supports420, an overcoating layer415, and connection lines. Therefore, redundant description of the same components will not be provided.FIG.4Aillustrates only a region A ofFIG.3for convenience of explanation. Also,FIG.4Aillustrates only a first connection line481among the connection lines, and the same may apply to a second connection line.

Referring toFIG.4A, the plurality of first substrates411includes a first part P1and a second part P2. The first part P1is a region where the plurality of inorganic insulating layers such as the buffer layer112, the gate insulating layer113, and the interlayer insulating layer114is disposed. The second part P2is a region covered by the overcoating layer415. The first part P1may have a first thickness T1, and the second part P2may have a second thickness T2which is smaller than the first thickness T1of the first part P1. In this case, the first thickness T1may be a distance between upper surfaces of the plurality of first substrates411in contact with the buffer layer112and lower surfaces of the plurality of first substrates411in contact with the lower substrate110.

Referring toFIG.4A, the plurality of connection supports420may be connected to the second part P2of the plurality of first substrates411, and the first connection line481may be disposed on upper surfaces of the plurality of connection supports420. In this case, the plurality of connection supports420may have the same thickness as the second part P2of the plurality of first substrates411.

Referring toFIG.4A, the first part P1adjacent to the second part P2may have an undercut portion. Specifically, during manufacturing of the stretchable display device400, the second part P2of the plurality of first substrates411and the plurality of inorganic insulating layers, such as the buffer layer112, the gate insulating layer113, and the interlayer insulating layer114, on the plurality of connection supports420may be etched and removed. This may occur when etching to form the connection lines181and182on the plurality of connection supports420as described herein or when etching the connection line120. Thus, in the embodiment in which the overcoating layer115is deposited after the connection line120is formed, the undercut will be present. Namely, when the plurality of inorganic insulating layers is etched, the second part P2of the plurality of first substrates411and a part of the upper surfaces of the plurality of connection supports420may also be slightly etched and therefore part of it is removed. Thus, the first part P1adjacent to the second part P2may have an undercut portion, i.e., a shape whose cross-sectional area or width gradually decreases from top to bottom. Also, the second part P2and the plurality of connection supports420may have a smaller thickness than the first part P1.

Referring toFIG.4A, the overcoating layer415may be disposed in the first part P1adjacent to the second part P2to compensate for the undercut portion of the first part P1adjacent to the second part P2. That is, the overcoating layer415may fill a space under an upper surface of the first part P1, and, thus, the first connection line481cannot be disposed on the undercut portion. Thus, the overcoating layer415can suppress line opening in the first connection line481.

FIG.4Bis an image of a stretchable display device according to Comparative Example. It is assumed that in the stretchable display device shown inFIG.4B, a plurality of first substrates11and a plurality of connection supports20are formed of PI and a plurality of inorganic insulating layers including a buffer layer12, a gate insulating layer13, and an interlayer insulating layer14is formed of SiNx. Also, it is assumed that in the stretchable display device shown inFIG.4B, a first connection line81is formed of Cu. Further, a thickness of the plurality of first substrates11is set to 6 μm and the total thickness of the buffer layer12, the gate insulating layer13, and the interlayer insulating layer14is set to 3600 Å. Also, a thickness of the first connection line81is set to 5000 Å. Moreover, it is assumed that the buffer layer12, the gate insulating layer13, and the interlayer insulating layer14are disposed on the plurality of first substrates11, and the first connection line81is disposed on the plurality of first substrates11and the plurality of connection supports20.

Referring toFIG.4B, while the buffer layer12, the gate insulating layer13, and the interlayer insulating layer14are etched, some of the plurality of first substrates11adjacent to the plurality of connection supports20and some of the plurality of connection supports20are also etched. Thus, it can be seen that a part of the plurality of first substrates11adjacent to the plurality of connection supports20has an undercut portion and the plurality of connection supports20has a smaller thickness than the plurality of first substrates11.

Further, referring toFIG.4B, the first connection line81may be disposed in a region of the plurality of first substrates11where the undercut portion is formed. However, if the first connection line81is disposed along the undercut portion of the plurality of first substrates11, line opening may occur in the first connection line81due to a step on the undercut portion as indicated by B region inFIG.4B.

In the stretchable display device400according to another example embodiment of the present disclosure, the overcoating layer415is disposed to cover the second part P2of the plurality of first substrates411and the first part P1adjacent to the second part P2. Thus, when a connection line is formed, it is possible to suppress line opening in the connection line. Specifically, while the buffer layer112, the gate insulating layer113, and the interlayer insulating layer114are etched, the first part P1adjacent to the second part P2of the plurality of first substrates411may also be etched. Thus, the first part P1adjacent to the second part P2may have an undercut portion. The overcoating layer415may be disposed to cover the second part P2of the plurality of first substrates411and the first part P1adjacent to the second part P2. Therefore, the overcoating layer415can compensate for the undercut portion of the first part P1adjacent to the second part P2. Also, since the connection line is disposed on the overcoating layer415, it is possible to suppress line opening in the connection line when the connection line is formed.

In other embodiments, the entire individual substrates111are fully formed, including the overcoating layer115and the light emitting element160and then it is placed on the lower substrate110. In such embodiments, an undercut of the sidewall of inorganic layer112will not be present.

FIG.5is a schematic cross-sectional view illustrating a sub-pixel of a stretchable display device according to yet another example embodiment of the present disclosure. A stretchable display device500shown inFIG.5is substantially the same as the stretchable display device100shown inFIG.1throughFIG.3except an overcoating layer515, a plurality of pads570, and a plurality of connection lines580. Therefore, redundant description of the same components will not be provided.

Referring toFIG.5, the plurality of pads570is disposed on the same layer as the gate electrode151which is an electrode of the transistor150. Specifically, the plurality of pads570may be disposed on the gate insulating layer113and connected to the connection lines580through contact holes formed in the interlayer insulating layer114and the overcoating layer515. More specifically, a gate pad571among the plurality of pads570may be connected to a first connection line581and a data pad572may be connected to a second connection line582.

Referring toFIG.5, the overcoating layer515includes a first surface S1and a second surface S2formed lower in height than the first surface S1. On the first surface S1of the overcoating layer515, a first connection pad191and a second connection pad192may be disposed. On the second surface S2, the first connection line581and the second connection line582may be disposed. Thus, the first connection line581and the second connection line582are connected to the plurality of pads570at a lower position. Therefore, the first connection line581and the second connection line582may be disposed in a smaller region on a side surface of the overcoating layer515. The overcoating layer is therefore a planarizing layer in some embodiments.

In the stretchable display device500according to yet another example embodiment of the present disclosure, the plurality of pads570is disposed on the same layer as the gate electrode151. Thus, a step between the plurality of connection lines580can be reduced. That is, as shown inFIG.5, if the plurality of pads570is disposed on the same layer as the gate electrode151which is an electrode of the transistor150, a step between the plurality of pads570can be reduced. Also, the first connection line581and the second connection line582can be connected to the plurality of pads570at a lower position. Therefore, the first connection line581and the second connection line582are disposed on the second surface S2of the overcoating layer515. Thus, the plurality of connection lines580can be connected to the plurality of pads570at a lower position than the first surface S1of the overcoating layer515. Accordingly, in the stretchable display device500according to yet another example embodiment of the present disclosure, the plurality of pads570is disposed on the same layer as the gate electrode151. Thus, the plurality of connection lines580can be electrically connected to the plurality of pads570at a lower position. Therefore, when the stretchable display device500is stretched, stress generated on the plurality of connection lines580can be reduced. Thus, it is possible to suppress line opening in the plurality of connection lines580.

FIG.6is a schematic cross-sectional view illustrating a sub-pixel of a stretchable display device according to still another example embodiment of the present disclosure. A stretchable display device600shown inFIG.6is substantially the same as the stretchable display device100shown inFIG.1throughFIG.3except a gate insulating layer613, an interlayer insulating layer614, an overcoating layer615, a plurality of pads670, and a plurality of connection lines680. Also, a barrier shield metal (BSM)618and an active buffer619are further provided in the stretchable display device600. Therefore, redundant description of the same components will not be provided.

Referring toFIG.6, the BSM618is disposed on the buffer layer112. The BSM618may be metal pattern disposed on the plurality of first substrates111. The BSM618may be disposed on the plurality of first substrates111so as to overlap the active layer152of the transistor150. A cross-sectional width of the BSM618may be equal to or larger than a width of the active layer152of the transistor150. The BSM618may be formed of various metal materials. The BSM618may be floated or applied with a constant voltage.

The active buffer619is disposed on the BSM618. The active buffer619serves to insulate the BSM618from the active layer152of the transistor150. The active buffer619may be formed of the same material as the plurality of first substrates111. For example, the active buffer619may be formed as one or more inorganic layers of silicon nitride (SiNx) or silicon oxide (SiOx).

Referring toFIG.6, the plurality of pads670is disposed on the same layer as the BSM618. That is, all of the plurality of pads670may be disposed on the buffer layer112and spaced apart from the BSM618. For example, a gate pad671among the plurality of pads670may be disposed on the right side of the BSM618. Also, the gate pad671may be connected to a first connection line681through a contact hole formed in the active buffer619, the gate insulating layer613, the interlayer insulating layer614, and the overcoating layer615. A data pad672may be disposed on the left side of the BSM618. Also, the data pad672may be connected to a second connection line682through a contact hole formed in the active buffer619, the gate insulating layer613, the interlayer insulating layer614, and the overcoating layer615. The plurality of pads670may be formed of the same material as the BSM618, but is not limited thereto.

Referring toFIG.6, the overcoating layer615includes a first surface S1and a second surface S2formed lower in height than the first surface S1. On the first surface S1of the overcoating layer615, the first connection pad191and the second connection pad192may be disposed. On the second surface S2, the first connection line681and the second connection line682may be disposed. Thus, the first connection line681and the second connection line682are connected to the plurality of pads670at a lower position. Therefore, the first connection line681and the second connection line682may be disposed in a smaller region on a side surface of the overcoating layer615.

The stretchable display device600according to still another example embodiment of the present disclosure may further include the floated BSM618. Thus, hydrogen or moisture can be blocked by the BSM618. Also, a laser irradiated during a laser release process can be blocked by the BSM618. Further, the BSM618can suppress a shift of a threshold voltage Vth of the transistor150which may occur when a potential on a surface of the lower substrate110increases.

In the stretchable display device600according to still another example embodiment of the present disclosure, the plurality of pads670is disposed on the same layer as the BSM618. Thus, a step between the plurality of connection lines680can be reduced. That is, as shown inFIG.6, if the plurality of pads670is disposed on the same layer as the BSM618, a step between the plurality of pads670can be reduced. Also, the first connection line681and the second connection line682can be connected to the plurality of pads670at a lower position. Therefore, the first connection line681and the second connection line682are disposed on the second surface S2of the overcoating layer615. Thus, the plurality of connection lines680can be connected to the plurality of pads670at a lower position than the first surface S1of the overcoating layer615. Accordingly, in the stretchable display device600according to still another example embodiment of the present disclosure, the plurality of pads670is disposed on the same layer as the BSM618. Thus, the plurality of connection lines680can be electrically connected to the plurality of pads670at a lower position. Therefore, when the stretchable display device600is stretched, stress generated on the plurality of connection lines680can be reduced. Thus, it is possible to suppress line opening in the plurality of connection lines680.

FIG.7is an enlarged plan view illustrating a stretchable display device according to still another example embodiment of the present disclosure.FIG.8is a schematic cross-sectional view illustrating a sub-pixel of the stretchable display device according to still another example embodiment of the present disclosure. A stretchable display device700shown inFIG.7andFIG.8is substantially the same as the stretchable display device100shown inFIG.1throughFIG.3except a plurality of first substrates711, a plurality of connection lines780, and a plurality of pads770. Therefore, redundant description of the same components will not be provided.

Referring toFIG.7, the plurality of first substrates711includes a central portion711aand a plurality of protrusions711bprotruding from the central portion711a. The central portion711ais a region where the sub-pixels SPX are disposed. The plurality of protrusions711brefers to regions where a plurality of contact holes CNT is disposed. In each of the plurality of protrusions711b, one of the plurality of contact holes CNT may be disposed.FIG.7illustrates that four protrusions711bare disposed on each side of the central portion711a, but the present disclosure is not limited thereto. The number of the plurality of protrusions711bmay vary depending on the design.

Referring toFIG.7, the plurality of protrusions711bmay decrease in width as they become farther from the central portion711a. Specifically, the plurality of protrusions711bmay have the largest width at a portion adjacent to the central portion711aand the smallest width at a portion connected to the plurality of connection supports120. In this case, the width of the plurality of protrusions711bat the portion connected to the plurality of connection supports120may be equal to a width of the plurality of connection supports120. Thus, when the stretchable display device700is stretched, stress generated on the plurality of protrusions711bis dispersed. Therefore, the stability in stretching of the stretchable display device700can be improved.

Referring toFIG.8, the plurality of pads770is disposed to be in contact with the buffer layer112, the gate insulating layer113, the interlayer insulating layer114, and the plurality of first substrates711. Specifically, the plurality of pads770may be disposed to be in contact with an upper surface of the interlayer insulating layer114and side surfaces of the buffer layer112, the gate insulating layer113and the interlayer insulating layer114. The plurality of pads770may also be disposed to be in contact with and upper surfaces of the plurality of first substrates711. Since the plurality of pads770is disposed to be in contact with a part of the upper surfaces of the plurality of first substrates711, the plurality of connection lines780can be connected to the plurality of pads770at a lower position.

Referring toFIG.8, an overcoating layer715is disposed to cover the plurality of pads770and the plurality of first substrates711. The overcoating layer715may be disposed to cover the upper surfaces and side surfaces of the plurality of pads770and the plurality of first substrates711.

Referring toFIG.8, the overcoating layer715includes a first surface S1and a second surface S2formed lower in height than the first surface S1. On the first surface S1of the overcoating layer715, the first connection pad191and the second connection pad192may be disposed. On the second surface S2and a side surface of the overcoating layer715, the plurality of connection lines780may be disposed. In this case, the contact holes CNT are formed under the second surface S2of the overcoating layer715. Thus, the plurality of connection lines780can be connected to the plurality of pads770. Specifically, a first connection line781may be connected to a gate pad771through a contact hole CNT formed in the overcoating layer715. Also, a second connection line782may be connected to a data pad772through a contact hole CNT formed in the overcoating layer715.

Referring toFIG.8, the plurality of connection supports120is connected to the plurality of protrusions711b. On upper surfaces of the plurality of connection supports120, the plurality of connection lines780may be disposed.

In the stretchable display device700according to still another example embodiment of the present disclosure, the plurality of contact holes CNT is disposed on the plurality of protrusions711b. Thus, a pixel PX and drive circuits may be disposed in a larger region on the first substrate711. The plurality of contact holes CNT is formed by etching a part of the overcoating layer715to connect the plurality of connection lines780to the plurality of pads770. When the plurality of contact holes CNT is formed, a process margin between an end of the first substrate711and the plurality of contact holes CNT and a process margin between the pixel PX and the plurality of contact holes CNT need to be considered. Therefore, if the plurality of contact holes CNT is located in the central portion711a, a pixel PX, drive circuits, and lines may be disposed in a smaller region on the central portion711a. Accordingly, in the stretchable display device700according to still another example embodiment of the present disclosure, the plurality of contact holes CNT is disposed on the plurality of protrusions711b. Thus, the plurality of connection lines780can be connected to the plurality of pads770on the plurality of protrusions711b. Therefore, the pixel PX, the drive circuits, and the lines may be disposed in a larger region on the first substrate711. For example, it is assumed that the central portion711aof the first substrate711has a width of 177 μm, a contact hole CNT has a size of 5 μm×5 μm, and a process margin is 2.5 μm. In this case, if the contact hole CNT is disposed in the protrusion711bas described in the still another example embodiment of the present disclosure, a utilized area can increase by about 11% compared to the case where the contact hole CNT is disposed in the central portion711a.

In the stretchable display device700according to still another example embodiment of the present disclosure, the plurality of pads770is disposed to be in contact with the upper surfaces of the plurality of first substrates711. Thus, a step between the plurality of connection lines780can be reduced. The plurality of pads770is disposed to be in contact with the upper surface of the interlayer insulating layer114, the side surfaces of the buffer layer112, the gate insulating layer113and the interlayer insulating layer114, and the upper surfaces of the plurality of first substrates711. Thus, the plurality of pads770can be in contact with the plurality of connection lines780on the plurality of protrusions711bof the plurality of first substrates711. Accordingly, in the stretchable display device700according to still another example embodiment of the present disclosure, the plurality of pads770is disposed to be in contact with the upper surfaces of the plurality of first substrates711. Thus, the plurality of connection lines780may be disposed at a lower position. Therefore, when the stretchable display device700is stretched repeatedly, stress generated on the plurality of connection lines780can be reduced and damage to the plurality of connection lines780can be reduced.

In the stretchable display device700according to still another example embodiment of the present disclosure, the plurality of protrusions711bof the plurality of first substrates711decreases in width as they become farther from the central portion711a. Thus, when the stretchable display device700is stretched, stress generated on the plurality of protrusions711bcan be reduced at a portion connected to the central portion711a. If the stretchable display device700is stretched, stress generated on the plurality of protrusions711bis larger at the portion connected to the central portion711aof the plurality of first substrates711than at the portion connected to the plurality of connection supports120. Thus, the plurality of protrusions711bmay be damaged at the portion connected to the central portion711a. Therefore, the plurality of protrusions711bhas a large width at the portion connected to the central portion711aand gradually decreases in width as they become farther from the central portion711a. Accordingly, in the stretchable display device700according to still another example embodiment of the present disclosure, damage to the plurality of protrusions711bat the portion connected to the central portion711acan be reduced.

FIG.9is a schematic cross-sectional view illustrating a sub-pixel of a stretchable display device according to still another example embodiment of the present disclosure. A stretchable display device900shown inFIG.9is substantially the same as the stretchable display device100shown inFIG.1throughFIG.3except an overcoating layer915and connection lines980. Therefore, redundant description of the same components will not be provided.

Referring toFIG.9, a surface of the overcoating layer915in contact with the plurality of connection lines980may be wrinkled. For example, at least a part of the overcoating layer915may be wrinkled with irregular creases. Thus, one surfaces of the plurality of connection lines980in contact with the surface the overcoating layer915are also wrinkled and thus can have a larger area in contact with the overcoating layer915.FIG.9illustrates that the entire surface of the overcoating layer915in contact with the plurality of connection lines980is wrinkled. However, the present disclosure is not limited thereto. Only a part of the surface of the overcoating layer915in contact with the plurality of connection lines980may be wrinkled. Further,FIG.9illustrates that the surface of the overcoating layer915is wrinkled with irregular creases. However, the present disclosure is not limited thereto. The surface of the overcoating layer915may be wrinkled with regular creases.

In the stretchable display device900according to still another example embodiment of the present disclosure, the surface of the overcoating layer915in contact with the plurality of connection lines980is wrinkled. Thus, when the stretchable display device900is stretched, peeling of the plurality of connection lines980from the overcoating layer915can be suppressed. If the surface of the overcoating layer915in contact with the plurality of connection lines980is wrinkled, a contact area between the plurality of connection lines980and the overcoating layer915can increase. Therefore, the adhesion strength between the plurality of connection lines980and the overcoating layer915can be enhanced. Also, when the stretchable display device900is stretched, the wrinkled overcoating layer915and the connection lines980can be stretched more easily. Accordingly, in the stretchable display device900according to still another example embodiment of the present disclosure, the surface of the overcoating layer915in contact with the plurality of connection lines980is wrinkled. Thus, a contact area between the plurality of connection lines980and the overcoating layer915can increase and spare space to be used during stretching of the stretchable display device900can be secured. Therefore, when the stretchable display device900is stretched, peeling of the plurality of connection lines980from the overcoating layer915can be suppressed.

FIG.10is a schematic perspective view illustrating a sub-pixel of a stretchable display device according to still another example embodiment of the present disclosure. A stretchable display device1000shown inFIG.10is substantially the same as the stretchable display device100shown inFIG.1throughFIG.3except an overcoating layer1015. Therefore, redundant description of the same components will not be provided. For convenience of explanation,FIG.10illustrates only the plurality of first substrates111, the plurality of connection supports120, the plurality of connection lines180, and the overcoating layer1015of the stretchable display device1000.

Referring toFIG.10, the plurality of first substrates111includes a plurality of first regions A1and a plurality of second regions A2. The plurality of first regions A1refers to regions where the plurality of first substrates111and the plurality of connection supports120are connected to each other. The plurality of second regions A2refers to regions other than the plurality of first regions A1. That is, the plurality of first regions A1refers to regions where the plurality of connection lines180is disposed on the plurality of first substrates111. The plurality of second regions A2refers to regions where the plurality of connection lines180is not disposed.

Referring toFIG.10, the overcoating layer1015may be disposed to have different incline angles in the plurality of first regions A1and the plurality of second regions A2. Specifically, an overcoating layer1015adisposed in the plurality of first regions A1may have a smaller incline angle than an overcoating layer1015bdisposed in the plurality of second regions A2. Thus, the plurality of connection lines180disposed on the overcoating layer1015ain the plurality of first regions A1may be disposed to have a low incline angle.

In the stretchable display device1000according to still another example embodiment of the present disclosure, it is possible to selectively regulate the incline angle of the overcoating layer1015in the regions where the plurality of connection lines180is disposed. For example, the overcoating layer1015bin the plurality of second regions A2where the plurality of connection lines180is not disposed may be disposed to have a high incline angle. However, it is advantageous to dispose the overcoating layer1015awith a low incline angle in the plurality of first regions A1where the plurality of connection lines180is disposed. That is, the overcoating layer1015ain the plurality of first regions A1where the plurality of connection lines180is disposed has a lower incline angle than the overcoating layer1015bin the plurality of second regions A2. Thus, the plurality of connection lines180can be disposed to have a low incline angle. Therefore, the overcoating layer1015in the plurality of first regions A1is disposed with a low incline angle by selectively regulating the incline angle of the overcoating layer1015depending on the region. Accordingly, when the stretchable display device1000is stretched, damage to the plurality of connection lines180can be reduced.

FIG.11is a schematic cross-sectional view as taken along a line XI-XI′ ofFIG.1according to still another example embodiment of the present disclosure. The stretchable display device1100shown inFIG.11is similar to the stretchable display device600shown inFIG.6except a plurality of inorganic insulating layers and organic insulating layers, a middle line ML and a third connection pad1193. Therefore, redundant description of the same components that are common to both will not be provided.

Referring toFIG.11, a plurality of inorganic insulating layers is disposed on the plurality of first substrates111and the plurality of second substrates121. The plurality of inorganic insulating layers may include a buffer layer1112, an active buffer1119, a gate insulating layer1113, a first interlayer insulating layer1114a, a second interlayer insulating layer1114band a passivation layer1194. A plurality of inorganic insulating layers disposed on the plurality of first substrates111may be disposed apart from a plurality of inorganic insulating layers disposed on the plurality of second substrates121.

The buffer layer1112is disposed on the plurality of first substrates111and the plurality of second substrates121. The buffer layer1112may be referred to as a first inorganic insulating layer. The buffer layer1112may include a first part P1and a second part P2. The first part P1of the buffer layer1112has a first width W1and may be disposed to be in contact with upper surfaces of the plurality of first substrates111. Further, the second part P2of the buffer layer1112has a second width W2and may be disposed on the first part P1. The second width W2of the second part P2of the buffer layer1112may be smaller than the first width W1of the first part P1. That is, the buffer layer1112may have a stepped side surface.

The active buffer1119and the gate insulating layer1113are disposed on the buffer layer1112. The active buffer1119and the gate insulating layer1113may be referred to as second inorganic insulating layers.

The active buffer1119is disposed on the buffer layer1112. The active buffer1119may have the same width as the second width W2of the second part P2of the buffer layer1112and may be disposed to be in contact with an upper surface of the second part P2of the buffer layer1112, but is not limited thereto. The active buffer1119may have a smaller width than the second width W2of the second part P2of the buffer layer1112.

The active layer152is disposed on the active buffer1119, and the gate insulating layer1113is disposed on the active buffer1119and the active layer. The gate insulating layer1113may have the same width as the active buffer1119. That is, the gate insulating layer1113may be formed to have the same width through the same process at the same time as the active buffer1119. Thus, the gate insulating layer1113may have the same width as the second width W2of the second part P2of the buffer layer1112, but is not limited thereto. The gate insulating layer1113may have a smaller width than the second width W2of the second part P2of the buffer layer1112.

The gate electrode151is disposed on the gate insulating layer1113. The gate electrode151may be disposed to overlap the active layer152or the BSM618, but is not limited thereto.

An interlayer insulating layer1114and the passivation layer1194are disposed on the gate insulating layer1113. The interlayer insulating layer1114and the passivation layer1194may be referred to as third inorganic insulating layers.

The interlayer insulating layer1114may include the first interlayer insulating layer1114aand the second interlayer insulating layer1114b.

The first interlayer insulating layer1114ais disposed on the gate electrode151and the gate insulating layer1113. The first interlayer insulating layer1114amay be disposed to cover an upper surface and a side surface of the gate insulating layer1113, a side surface of the active buffer1119and an upper surface and a side surface of the buffer layer1112. In this case, the first interlayer insulating layer1114amay be disposed to cover an upper surface of the first part P1and a side surface of the second part P2of the buffer layer1112.

The middle line ML is disposed on the first interlayer insulating layer1114a. The middle line ML may be in contact with the BSM618through a contact hole formed in the first interlayer insulating layer1114a, the gate insulating layer1113and the active buffer1119. The middle line ML serves to apply a constant voltage to the BSM618and electrically connects a source electrode1153and the BSM618. If the middle line ML is designed to have a short length according to the design of the BSM618and a transistor1150, the middle line ML may be referred to as a middle electrode.

The second interlayer insulating layer1114bis disposed on the first interlayer insulating layer1114aand the middle line ML. The second interlayer insulating layer1114bmay be disposed to cover an upper surface and a side surface of the first interlayer insulating layer1114a.

The source electrode1153, a drain electrode1154and a third connection pad1193are disposed on the second interlayer insulating layer1114b.

The source electrode1153and the drain electrode1154may be electrically connected to the active layer152through a contact hole formed in the gate insulating layer1113, the first interlayer insulating layer1114aand the second interlayer insulating layer1114b. In this case, the source electrode1153may be electrically connected to the active layer152through the middle line ML disposed on the first interlayer insulating layer1114a.

The third connection pad1193is disposed on the second interlayer insulating layer1114bformed on the plurality of second substrates121. The third connection pad1193may be electrically connected to the source electrode1153or the drain electrode1154formed on the plurality of first substrates111through a second connection line1182. The third connection pad1193refers to a pad to which the COF130is bonded and may be used for transferring a signal from the COF130to a sub-pixel.

The passivation layer1194is disposed on the second interlayer insulating layer1114b. The passivation layer1194may be disposed on the plurality of first substrates111so as to cover a part of upper surfaces and side surfaces of the source electrode1153, the drain electrode1154and the second interlayer insulating layer1114b. The passivation layer1194may serve as a protective layer for protecting the transistor1150against permeation of moisture, oxygen, and the like. The passivation layer1194may be formed of an inorganic material and formed as one or more layers, but is not limited thereto.

An overcoating layer1115is disposed on the passivation layer1194. The overcoating layer1115may be disposed to cover upper surfaces and side surface of the plurality of inorganic insulating layers disposed on the plurality of first substrates111and the plurality of second substrates121. Specifically, the overcoating layer1115may be disposed to cover an upper surface and a side surface of the passivation layer1194, a side surface of the interlayer insulating layer1114and a part of a side surface of the buffer layer1112.

The second connection line1182is disposed on the overcoating layer1115. The second connection line1182may be disposed to cover a side surface and a part of an upper surface of the overcoating layer1115and upper surfaces of the plurality of connection supports120.

The second connection line1182may be electrically connected to the source electrode1153or the drain electrode1154and the third connection pad1193through a contact hole formed in the passivation layer1194and the overcoating layer1115. In this case, the second connection line1182may electrically connect the source electrode1153or the drain electrode1154disposed on the plurality of first substrates111and the third connection pad1193disposed on the plurality of second substrates121.

Meanwhile, in some example embodiments, the first part P1and the second part P2of the buffer layer1112may have the same width. That is, the second width W2of the second part P2of the buffer layer1112is the same as the first width W1of the first part P1, and, thus, the width of the buffer layer1112can be defined as the first width W1. In this case, the active buffer1119may include a first part P1and a second part P2on the first part P1. Also, the first part P1of the active buffer1119may have a first width W1and the second part P2of the active buffer1119may have a second width W2which is smaller than the first width W1of the first part P1. Otherwise, the active buffer1119may have the first width W1which is the same as the first width W1of the buffer layer1112. Also, the gate insulating layer1113may include a first part P1and a second part P2on the first part P1. Further, the first part P1of the gate insulating layer1113may have a first width W1and the second part P2of the gate insulating layer1113may have a second width W2which is smaller than the first width W1of the first part P1.

Further, in some example embodiments, the first part P1and the second part P2of the buffer layer1112may have the same width. That is, the second width W2of the second part P2of the buffer layer1112is the same as the first width W1of the first part P1, and, thus, the width of the buffer layer1112can be defined as the first width W1. In this case, the active buffer1119and the gate insulating layer1113may be formed to have the second width W2which is smaller than the first width W1. Thus, the buffer layer1112, the active buffer1119and the gate insulating layer1113may form a stepped structure.

FIG.12AthroughFIG.12Mare process diagrams provided to explain a manufacturing process of the stretchable display device illustrated inFIG.11.

Referring toFIG.12A, a sacrificial layer SL and a temporary substrate1211are disposed on a subsidiary substrate SS. The subsidiary substrate SS is configured to support the temporary substrate1211during the manufacturing process of the stretchable display device1100. The subsidiary substrate SS may be a glass substrate, but is not limited thereto.

The sacrificial layer SL is disposed on the subsidiary substrate SS. The sacrificial layer SL is used to separate the subsidiary substrate SS from the temporary substrate1211. If a laser is irradiated to the sacrificial layer SL, the adhesion strength between the subsidiary substrate SS and the temporary substrate1211may decrease. By irradiating a laser to the sacrificial layer SL, the subsidiary substrate SS may be removed from the temporary substrate1211. The sacrificial layer SL may be formed of amorphous silicon (a-Si) or silicon nitride (SiNx), but is not limited thereto.

Then, the temporary substrate1211is disposed on the sacrificial layer SL. In the temporary substrate1211, a stiff area SA and an elastic area EA may be defined. Specifically, the temporary substrate1211may be removed in part in a follow-up process and may become the plurality of first substrates111, the plurality of connection supports120or the plurality of second substrates121. For example, the stiff area SA of the temporary substrate1211may become the plurality of first substrates111or the plurality of second substrates121, and the elastic area EA of the temporary substrate1211may become the plurality of connection supports120. Thus, the temporary substrate1211may be formed of a plastic material having flexibility, such as polyimide (PI), polyacrylate, and polyacetate, but is not limited thereto.

Then, a buffer layer material1212is formed on the temporary substrate1211. Specifically, the buffer layer material1212may be formed in the stiff area SA and the elastic area EA of the temporary substrate1211. The buffer layer material1212may be referred to as a first inorganic insulating material. For example, the buffer layer material1212may be an inorganic insulating material formed of silicon nitride (SiNx), silicon oxide (SiOx), silicon oxynitride (SiON), or the like.

Then, the BSM618is formed on the buffer layer material1212, and an active buffer material1219is formed on the buffer layer material1212and the BSM618. The active buffer material1219may be referred to as a second inorganic insulating material. Specifically, the active buffer material1219may be formed in the stiff area SA and the elastic area EA of the temporary substrate1211. The active buffer material1219may be an inorganic insulating material formed of silicon nitride (SiNx) or silicon oxide (SiOx).

Then, the active layer152is formed on the active buffer material1219, and a gate insulating layer material1213is formed on the active buffer material1219and the active layer. The gate insulating layer material1213may be referred to as a second inorganic insulating material. The gate insulating layer material1213may be an inorganic insulating material formed of silicon nitride (SiNx) or silicon oxide (SiOx).

Then, the gate electrode151is formed on the gate insulating layer material1213.

Then, referring toFIG.12B, a second inorganic insulating layer is formed by selectively removing a portions of the second inorganic insulating material disposed in the elastic area EA and a part of the stiff area SA adjacent to the elastic area EA. Specifically, the active buffer1119and the gate insulating layer1113may be formed by removing the active buffer material1219and the gate insulating layer material1213disposed in the elastic area EA and a part of the stiff area SA adjacent to the elastic area EA. For example, a photoresist PR is formed on the active buffer material1219and the gate insulating layer material1213disposed on the other part of the stiff area SA. Then, the active buffer material1219and the gate insulating layer material1213disposed in the elastic area EA and a part of the stiff area SA adjacent to the elastic area EA are removed to form the active buffer1119and the gate insulating layer1113. Thus, only the buffer layer material1212may remain in the elastic area EA and a part of the stiff area SA adjacent to the elastic area EA.

Meanwhile, the process of forming the second inorganic insulating layer may include a process of removing a part of a first inorganic insulating material disposed in the elastic area EA except a part overlapping the active buffer1119and the gate insulating layer1113and a part of the stiff area SA adjacent to the elastic area EA. For example, in the process of forming the second inorganic insulating layer, a part of the buffer layer material1212disposed in the elastic area EA and a part of the stiff area SA adjacent to the elastic area EA may be removed. Thus, only a part of the buffer layer material1212having a smaller thickness than the buffer layer material1212disposed in the stiff area SA may remain in the elastic area EA and a part of the stiff area SA adjacent to the elastic area EA.

Then, referring toFIG.12CandFIG.12D, a third inorganic insulating material is formed on the first inorganic insulating material and the second inorganic insulating layer. The third inorganic insulating material may include a first interlayer insulating layer material1214a, a second interlayer insulating layer material1214band a passivation layer material1294.

Referring toFIG.12C, the first interlayer insulating layer material1214ais formed on the buffer layer material1212, the active buffer1119and the gate insulating layer1113. The first interlayer insulating layer material1214amay be formed of an inorganic insulating material such as silicon nitride (SiNx) or silicon oxide (SiOx).

Then, the middle line ML is formed on the first interlayer insulating layer material1214a. The middle line ML may be connected to the BSM618through a contact hole formed in the first interlayer insulating layer material1214a, the gate insulating layer1113and the active buffer1119.

Then, referring toFIG.12D, the second interlayer insulating layer material1214bis formed on the first interlayer insulating layer material1214aand the middle line ML. The second interlayer insulating layer material1214bmay be identical to the first interlayer insulating layer material1214a, but is not limited thereto.

Then, the source electrode1153, the drain electrode1154and the third connection pad1193are formed on the second interlayer insulating layer material1214b. Also, the passivation layer material1294is formed on the second interlayer insulating layer material1214b, the source electrode1153, the drain electrode1154and the third connection pad1193. The passivation layer material1294may be formed of an inorganic material that suppresses the permeation of moisture and oxygen into the stretchable display device1100.

Then, referring toFIG.12E, a first inorganic insulating layer and a third inorganic insulating layer may be formed by removing the first inorganic insulating material and third inorganic insulating material disposed in the elastic area EA and the stiff area SA adjacent to the elastic area EA. Specifically, the buffer layer material1212, the first interlayer insulating layer material1214a, the second interlayer insulating layer material1214band the passivation layer material1294disposed in the elastic area EA and the stiff area SA adjacent to the elastic area EA may be removed. Thus, the buffer layer1112, the first interlayer insulating layer1114a, the second interlayer insulating layer1114band the passivation layer1194may be formed. For example, the photoresist PR may be coated on the buffer layer material1212, the first interlayer insulating layer material1214a, the second interlayer insulating layer material1214band the passivation layer material1294disposed in a part of the stiff area SA. Then, the buffer layer material1212, the first interlayer insulating layer material1214a, the second interlayer insulating layer material1214band the passivation layer material1294disposed in the elastic area EA and the stiff area SA adjacent to the elastic area EA may be removed. Thus, the buffer layer1112, the first interlayer insulating layer1114a, the second interlayer insulating layer1114band the passivation layer1194may be formed. Therefore, a plurality of inorganic insulating layers may not be disposed in the elastic area EA and the stiff area SA adjacent to the elastic area EA. Also, an upper surface of the temporary substrate1211in the elastic area EA and the stiff area SA adjacent to the elastic area EA may be exposed.

Then, referring toFIG.12F, the overcoating layer1115is formed on the passivation layer1194. The overcoating layer1115may be referred to as an organic insulating layer. The overcoating layer1115may be formed by forming and then patterning an overcoating layer material on the passivation layer1194. Thus, the overcoating layer1115may be patterned to expose a part of the drain electrode1154, the upper surface of the temporary substrate1211and a part of the third connection pad1193.

Then, referring toFIG.12G, the second connection line1182is formed on the overcoating layer1115and the temporary substrate1211. The second connection line1182may connect stiff areas SA adjacent to each other among a plurality of stiff areas SA on the temporary substrate1211. For example, as illustrated inFIG.12G, the second connection line1182may electrically connect the drain electrode1154disposed in a stiff area SA and the third connection pad1193disposed in another stiff area SA among the plurality of stiff areas SA.

Referring toFIG.12HandFIG.12I, a mask pattern MP is formed on the overcoating layer1115and the second connection line1182. The mask pattern MP may be used for removing the temporary substrate1211in an area that does not overlap an organic insulating layer and a plurality of connection lines. Specifically, the mask pattern MP may be formed on the overcoating layer1115and the second connection line1182. Then, the temporary substrate1211may be removed from a part of the elastic area EA where the second connection line1182is not disposed to form the plurality of first substrates111and the plurality of connection supports120. Therefore, the mask pattern MP may be formed of a material having a lower etching rate in an etchant than the temporary substrate1211. For example, if the temporary substrate1211is etched using the photoresist PR, the photoresist PR may be etched earlier than the temporary substrate1211. Thus, the mask pattern MP may be formed of a transparent conductive oxide such as ITO, IZO, ITZO, ZnO, and TO, but is not limited thereto.

Referring toFIG.12JandFIG.12K, after the plurality of first substrates111and the plurality of connection supports120are formed, the mask pattern MP formed on the overcoating layer1115and the second connection line1182is removed.

Referring toFIG.12LandFIG.12M, after the subsidiary substrate SS and the sacrificial layer SL disposed under the plurality of first substrates111and the plurality of connection supports120are removed, the lower substrate110is disposed. The lower substrate110may be disposed under the plurality of first substrates111and the plurality of connection supports120to support and protect various components disposed on the plurality of first substrates111and the plurality of connection supports120.

In a method of manufacturing the stretchable display device1100according to still another example embodiment of the present disclosure, an inorganic insulating material on the temporary substrate1211is removed through a plurality of processes rather than a single process. That is, as described above, in the method of manufacturing the stretchable display device1100according to still another example embodiment of the present disclosure, a patterning process of the buffer layer material1212, the active buffer material1219and the gate insulating layer material1213is performed first. Thus, the buffer layer1112, the active buffer1119and the gate insulating layer1113are formed first. Then, a patterning process of the first interlayer insulating layer material1214a, the second interlayer insulating layer material1214band the passivation layer material1294is performed. Thus, the first interlayer insulating layer1114a, the second interlayer insulating layer1114band the passivation layer1194are formed. In the method of manufacturing the stretchable display device1100according to still another example embodiment of the present disclosure, the buffer layer material1212, the active buffer material1219, the gate insulating layer material1213, the first interlayer insulating layer material1214a, the second interlayer insulating layer material1214band the passivation layer material1294disposed in the elastic area EA need to be removed. However, the elastic area EA is greater in size than the stiff area SA, and it is difficult in terms of uniformity to remove all the inorganic materials disposed in the wide area through a single process. Therefore, in the method of manufacturing the stretchable display device1100according to still another example embodiment of the present disclosure, the patterning process of the buffer layer material1212, the active buffer material1219and the gate insulating layer material1213is performed first. Then, the patterning process of the first interlayer insulating layer material1214a, the second interlayer insulating layer material1214band the passivation layer material1294is performed. Thus, uniformity in the patterning process of the inorganic materials can be secured.

Also, in the method of manufacturing the stretchable display device1100according to still another example embodiment of the present disclosure, when the second inorganic insulating layer is patterned and formed, a part of the first inorganic insulating material is left on the elastic area EA and the stiff area SA adjacent to the elastic area EA. Thus, when an inorganic material or metal material is formed in a follow-up process, it is possible to suppress peeling of the inorganic material or metal material from the temporary substrate1211. For example, if all the first inorganic insulating material on the elastic area EA and the stiff area SA adjacent to the elastic area EA is removed when the second inorganic insulating layer is formed, an inorganic material or metal material may be formed on the temporary substrate1211in a follow-up process. However, the temporary substrate1211formed of the first inorganic insulating material and the organic material has different surface energies. Therefore, when the inorganic material or metal material is formed on the temporary substrate1211, the inorganic material or metal material may peel off from the temporary substrate1211. Accordingly, when the second inorganic insulating layer is patterned and formed, a part of the first inorganic insulating material is left on the elastic area EA and the stiff area SA adjacent to the elastic area EA. Thus, an inorganic material or metal material is deposited on the first inorganic insulating material in a follow-up process. Therefore, it is possible to suppress peeling of the inorganic material or metal material.

Further, in the method of manufacturing the stretchable display device1100according to still another example embodiment of the present disclosure, when the second inorganic insulating layer is patterned and formed, a part of the first inorganic insulating material is left on the elastic area EA and the stiff area SA adjacent to the elastic area EA. Thus, it is possible to suppress the formation of an undercut portion in the temporary substrate1211. For example, all the first inorganic insulating material on the elastic area EA and the stiff area SA adjacent to the elastic area EA is removed when the second inorganic insulating layer is formed, a part of the stiff area SA adjacent to a photoresist PR-coated portion of the temporary substrate1211is also etched. Therefore, an undercut portion may be formed in the temporary substrate1211. However, if an undercut portion is formed in a part of the temporary substrate1211, an inorganic material or metal material deposited in a follow-up process may be cut off from each other by the undercut portion. Accordingly, when a patterning process is performed, a part of the first inorganic insulating material is left on the elastic area EA and the stiff area SA adjacent to the elastic area EA. Thus, it is possible to suppress the formation of an undercut portion in the temporary substrate1211. Also, an inorganic material or metal material can be deposited in a follow-up process without being cut off from each other.

FIG.13is a schematic cross-sectional view illustrating a sub-pixel of a stretchable display device according to still another example embodiment of the present disclosure. A stretchable display device1300shown inFIG.13is substantially the same as the stretchable display device100shown inFIG.1throughFIG.3except an organic light-emitting diode (OLED)1360and a bank1316. Therefore, redundant description of the same components will not be provided.

Referring toFIG.13, the OLED1360is disposed corresponding to each of the plurality of sub-pixels SPX and emits light in a specific wavelength range. That is, the OLED1360may be a blue OLED that emits blue light, a red OLED that emits red light, a green OLED that emits green light, or a white OLED that emits white light, but is not limited thereto. If the OLED1360is a white OLED, the stretchable display device1300may further include a color filter.

The OLED1360includes an anode1361, an organic emission layer1362, and a cathode1363. Specifically, the anode1361is disposed on the overcoating layer115. The anode1361is an electrode configured to supply holes into the organic emission layer1362. The anode1361may be formed of a transparent conductive material having high work function. Herein, the transparent conductive material may include indium tin oxide (ITO), indium zinc oxide (IZO), and indium tin zinc oxide (ITZO). Further, if the stretchable display device1300is of top-emission type, the anode1361may further include a reflective plate.

The anode1361is disposed as separated for each sub-pixel SPX and electrically connected to the transistor150through the contact hole formed in the overcoating layer115. For example,FIG.13illustrates that the anode1361is electrically connected to the drain electrode154of the transistor150, but the anode1361may be electrically connected to the source electrode153.

The bank1316is formed on the anode1361, the connection lines180, and the overcoating layer115. The bank1316separates adjacent sub-pixels SPX from each other. The bank1316is disposed to cover at least a part of both sides of the adjacent anode1361and exposes a part of an upper surface of the anode1361. The bank1316may serve to suppress light emission of unintended sub-pixels SPX or color mixing which occurs when light is emitted from the sides of the anode1361due to concentration of current on the edges of the anode1361. The bank1316may be formed of acryl-based resin, benzocyclobutene (BCB)-based resin, or PI, but is not limited thereto.

The bank1316includes a contact hole for connecting the connection line180serving as a data line and the data pad172and a contact hole for connecting the connection line180serving as a gate line and the gate pad171.

The organic emission layer1362is disposed on the anode1361. The organic emission layer1362is configured to emit light. The organic emission layer1362may contain a light-emitting material, and the light-emitting material may include a phosphorescent material or a fluorescent material, but is not limited thereto.

The organic emission layer1362may be formed as a single emission layer. Otherwise, the organic emission layer1362may have a stack structure in which a plurality of emission layers with a charge generation layer interposed therebetween is laminated. Further, the organic emission layer1362may further include at least one organic layer of a hole transport layer, an electron transport layer, a hole block layer, an electron block layer, a hole injection layer, and an electron injection layer.

Referring toFIG.13, the cathode1363is disposed on the organic emission layer1362. The cathode1363is configured to supply electrons into the organic emission layer1362. The cathode1363may be formed of a transparent conductive oxide such as ITO, IZO, ITZO, zinc oxide (ZnO), and tin oxide (TO) or an ytterbium (Yb) alloy. Otherwise, the cathode1363may be formed of a metal material.

The cathode1363may be patterned to overlap each of the plurality of first substrates111. That is, the cathode1363may be formed only in a region overlapping the plurality of first substrates111and may not be formed a region between the plurality of first substrates111. The cathode1363is formed of a transparent conductive oxide, a metal material, and the like. Thus, if the cathode1363is formed between the plurality of first substrates111, the cathode1363may be damaged while the stretchable display device1300is stretched. Thus, the cathode1363may be formed on the plane so as to correspond to each of the plurality of first substrates111. Referring toFIG.13, the cathode1363may be formed in the region overlapping the plurality of first substrates111so as not to overlap the region which is disposed the connection lines180.

Unlike the general organic light-emitting display device, the stretchable display device1300according to still another embodiment of the present disclosure includes the cathodes1363patterned corresponding to the plurality of first substrates111. Therefore, the cathodes1363respectively disposed on the plurality of first substrates111can be independently supplied with low-potential power through the connection lines180.

Referring toFIG.13, an encapsulation layer1317is disposed on the OLED1360. The encapsulation layer1317covers the OLED1360to be in contact with a part of an upper surface of the bank1316and thus seals the OLED1360. Thus, the encapsulation layer1317protects the OLED1360against permeation of moisture or air from the outside or physical impacts.

The encapsulation layer1317covers the cathodes1363patterned to overlap the plurality of first substrates111, respectively, and may be formed for each of the plurality of first substrates111. That is, the encapsulation layer1317may be disposed to cover a single cathode1363disposed on a single first substrate111, and the encapsulation layers1317disposed on the respective first substrates111may be spaced apart from each other.

The encapsulation layer1317may be formed only in the region overlapping the plurality of first substrates111. As described above, the encapsulation layer1317may be configured including an inorganic layer. Therefore, the encapsulation layer1317may be easily damaged, such as cracked, while the stretchable display device1300is stretched. Particularly, since the OLED1360is vulnerable to moisture or oxygen, if the encapsulation layer1317is damaged, the reliability of the OLED1360may be degraded. Therefore, in the stretchable display device1300according to still another embodiment of the present disclosure, the encapsulation layer1317is not formed in the region between the plurality of first substrates111. Thus, even when the stretchable display device1300is deformed by bending or stretching, it is possible to minimize damage to the encapsulation layer1317.