KR20180014404A - Organic light emitting display device and method of manufacturing the same - Google Patents

Abstract

A flexible display device according to an embodiment of the present invention is disclosed. The flexible display device comprises: a flexible substrate having a display region, a pad region extending from the display region, and a bending region extending from a pad region; a first buffer layer which is disposed on the flexible substrate and has a plurality of layers, and whose thickness in the bending region is thinner than that in the other regions except the bending region; a first protective member disposed on the first buffer layer in the pad region; a first insulating layer disposed on the first protective member in the pad region; a gate line disposed on the first insulating layer and extending from the display region; a second insulating layer disposed on the gate line in the pad region; a connection line electrically connected to the gate line; and a second buffer layer covering the gate line, wherein a portion of the connection line is disposed on the second insulating layer and the other portions are disposed on the first buffer layer in the bending region.

Description

Technical Field [0001] The present invention relates to an organic light emitting diode (OLED) display device and a method of manufacturing the same,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible display device and a method of manufacturing the same.

The image display device that realizes various information on the screen is a core technology of the information communication age and it is becoming thinner, lighter, more portable and higher performance. Accordingly, an organic light emitting display device for displaying an image by controlling the amount of light emitted from the organic light emitting device has attracted attention.

The organic light emitting device is advantageous in that it can be made thin as a self-luminous device using a thin light emitting layer between electrodes. A general organic light emitting display has a structure in which a pixel driving circuit and an organic light emitting element are formed on a substrate, and light emitted from the organic light emitting element passes through a substrate or a barrier layer to display an image.

Since the organic light emitting display device is implemented without a separate light source device, it is easy to be implemented as a flexible display device. At this time, a flexible material such as plastic or metal foil is used as the substrate of the organic light emitting display device.

On the other hand, when the organic light emitting display device is implemented as a flexible display device, studies are being conducted to flex or bend various portions of the display device using the flexible nature thereof. These studies are mainly performed for new designs and UI / UX, and in some cases these studies are performed to reduce the area of display edges.

It is an object of the present invention to provide a flexible display device in which the manufacturing process is simplified and a manufacturing method thereof.

The problems of the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

According to one embodiment of the present disclosure, a flexible display device is provided. A flexible display device includes: a flexible substrate having a display region, a pad region extending in a display region, and a bending region extending in a pad region; a flexible substrate disposed on the flexible substrate and having a plurality of layers, A first protective layer disposed on the first buffer layer in the pad region, a first insulating layer disposed on the first protective layer in the pad region, a second insulating layer disposed on the first insulating layer, And a second buffer layer covering the gate wiring extending from the display region, the second insulating layer disposed on the gate wiring in the pad region, the connection wiring electrically connected to the gate wiring, and the connection wiring, Is disposed on the second insulating layer in the pad region, and a portion other than the one portion is disposed on the first buffer layer in the bending region.

The first protection member may be provided so as to be spaced apart from another adjacent first protection member.

The first protective member may be provided such that a portion of the first insulating layer and the first buffer layer in the bending region can be removed by the same patterning equipment.

The flexible display device further includes a thin film transistor protecting member disposed on the first buffer layer in the display area, and the first protecting member may be the same material as the thin film transistor protecting member.

The flexible display device may further include a second protection member disposed between the first insulation layer and the second insulation layer.

The second protective member may be the same material as the gate wiring.

The second protection member may be provided to prevent the flexible substrate from being exposed between the first protection member and the adjacent first protection member to prevent the foreign matter from being present.

The second protection member can prevent another connection wiring adjacent to the connection wiring from being short-circuited.

The end of the second protective member may be provided so as to be located inside the end of the second insulating layer.

A method of manufacturing a flexible display device according to an embodiment of the present invention includes forming a first buffer layer having a plurality of layers on a flexible substrate having a display region, a pad region extending in a display region, and a bending region extending in a pad region, Patterning the first protective member on a portion of the first buffer layer in the pad region and the bending region; forming a first insulating layer on the first buffer layer to cover the first protective member; Sequentially forming a first insulating layer, a second insulating layer covering the gate wiring and the gate wiring extending from the display region on the first insulating layer, exposing the first protecting member in the bending region, Forming a connection wiring on the first buffer layer of the second insulating layer and the first bending region of the pad region so as to be connected to the gate wiring in a manner of being electrically connected with the gate wiring; And forming a second buffer layer for covering the wiring.

The manufacturing method of the flexible display device may further include the step of etching the first buffer layer in the bending region after the step of etching the exposed first protective member.

The step of etching the first buffer layer may be the same as the step of exposing the first protective member, but may be performed using a patterning equipment.

The step of patterning the first protective member may be patterned such that the first protective member is spaced apart from the pad region and the bending region with another adjacent first protective member.

The step of forming the gate wiring may include forming a second protective member covering a portion of the first insulating layer in the pad region and the bending region.

The step of exposing the first protective member may wet-etch a portion of the first insulating layer not covered with the second protective member in the bending region.

The step of etching the exposed first protective member may etch the second protective member and the exposed first protective member together.

The step of etching the exposed first protective member may include etching the second protective member in the pad region and the exposed first protective member so that the end of the second protective member is located inside the end of the second insulating layer .

The details of other embodiments are included in the detailed description and drawings.

Embodiments of the present invention can provide a flexible display device in which the uniformity between the bending regions is improved by using the same mask when the first and second bending regions are etched.

More specifically, the embodiments of the present invention can provide a flexible display device in which the manufacturing process is simplified by using the same masking equipment when the first and second bending areas are bend-edged.

Accordingly, the OLED display according to the embodiment of the present invention can be improved. The effects according to the embodiments of the present invention are not limited by the contents exemplified above, and more various effects are included in the specification.

Figure 1 shows an exemplary flexible display device that may be included in an electronic device.
Figure 2 shows an exemplary arrangement of flat and curved portions.
3A and 3B show the layout of the display area of the flexible display device according to the embodiment of the present invention.
4 is a cross-sectional view schematically showing a laminated structure of a flexible display device according to an embodiment of the present invention.
5 is a top view and a cross-sectional view of a bending pattern according to an embodiment of the present disclosure.
6A to 6C are schematic cross-sectional views showing an exemplary arrangement of components in a flexible display device.
Figures 7A and 7B show an exemplary structure of a multi-layer structure conductor.
Figure 8 shows some examples of deformation reduction design.
9A and 9B show a schematic view of a wiring structure having a plurality of sub-wirings.
Figure 10 shows several exemplary wiring structures with a diamond wiring design.
Figures 11A and 11B show schematic cross-sectional views of exemplary wiring structures.
Figures 12A and 12B show a schematic diagram of an exemplary strain relief interconnect structure with a modified portion.
13 is a cross-sectional view of a flexible display device according to an embodiment of the present invention.
FIGS. 14A to 14Q are diagrams illustrating a manufacturing step of a flexible display device according to an embodiment of the present invention.
15 is a cross-sectional view of a flexible display device according to another embodiment of the present invention.
16 is a cross-sectional view of a flexible display device according to another embodiment of the present invention.
17A to 17R are views showing a manufacturing procedure of a flexible display device according to another embodiment of the present invention.
18A to 18R are views showing a manufacturing procedure of a flexible display device according to another embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. To fully disclose the scope of the invention to a person skilled in the art, and the invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, and the like disclosed in the drawings for describing the embodiments of the present invention are illustrative, and thus the present invention is not limited thereto. Like reference numerals refer to like elements throughout the specification. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

Where the terms "comprises," "having," "consisting of," and the like are used in this specification, other portions may be added as long as "only" is not used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

In interpreting the constituent elements, it is construed to include the error range even if there is no separate description.

In the case of a description of the positional relationship, for example, if the positional relationship between two parts is described as 'on', 'on top', 'under', and 'next to' Or " direct " is not used, one or more other portions may be located between the two portions.

In the case of a description of a temporal relationship, for example, if the temporal relationship is described by 'after', 'after', 'after', 'before', etc., May not be continuous unless they are not used.

The first, second, etc. are used to describe various components, but these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, the first component mentioned below may be the second component within the technical spirit of the present invention.

The terms "X-axis direction "," Y-axis direction ", and "Z-axis direction" should not be construed solely by the geometric relationship in which the relationship between them is vertical, It may mean having directionality.

It should be understood that the term "at least one" includes all possible combinations from one or more related items. For example, the meaning of "at least one of the first item, the second item and the third item" means not only the first item, the second item or the third item, but also the second item and the second item among the first item, May refer to any combination of items that may be presented from more than one.

As used herein, a flexible display device refers to a flexible display device, including a bendable display device, a rollable display device, an unbreakable display device, a foldable display device, and the like. In this specification, the flexible organic light emitting display is one example of various flexible display devices.

It is to be understood that each of the features of the various embodiments of the present invention may be combined or combined with each other, partially or wholly, technically various interlocking and driving, and that the embodiments may be practiced independently of each other, It is possible.

The sizes and thicknesses of the individual components shown in the figures are shown for convenience of explanation and the present invention is not necessarily limited to the size and thickness of the components shown. Various embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

Figure 1 shows an exemplary flexible display device that may be included in an electronic device.

Referring to FIG. 1, the flexible display device 100 includes at least one active area, and an array of pixels is formed in the display area. At least one non-display area (in display area) may be disposed around the display area. That is, the non-display area may be adjacent to one or more sides of the display area. In Fig. 1, the non-display area surrounds a display area of a rectangular shape. However, the shape of the display region and the shape / arrangement of the non-display region adjacent to the display region are not limited to the example shown in Fig. The display area and the non-display area may be in a form suitable for the design of the electronic device on which the flexible display device 100 is mounted. Illustrative forms of the display area are pentagonal, hexagonal, circular, oval, and the like.

Each pixel in the display area may be associated with a pixel circuit. The pixel circuit may include one or more switching transistors and one or more driving transistors on a backplane. Each pixel circuit may be electrically connected to a gate line and a data line to communicate with one or more driving circuits such as a gate driver and a data driver located in the non-display area.

The driving circuit may be implemented with a thin film transistor (TFT) in the non-display region, as shown in FIG. This driving circuit may be referred to as a gate-in-panel (GIP). In addition, some components, such as a data driver IC, are mounted on a separate printed circuit board, and circuit films such as flexible printed circuit boards (FPCB), chip-on-film (COF), tape- (Pad / bump, pin, etc.) disposed in the non-display area. The non-display area may be bent with the connection interface so that the printed circuit (COF, PCB, etc.) may be positioned behind the flexible display device 100.

The flexible display device 100 may include various additional elements for generating various signals or driving pixels in the display area. An additional element for driving the pixel may include an inverter circuit, a multiplexer, an electrostatic discharge circuit, and the like. The flexible display device 100 may also include additional elements associated with functions other than pixel driving. For example, the flexible display device 100 may include additional elements that provide a touch sensing function, a user authentication function (e.g., fingerprint recognition), a multi-level pressure sensing function, a tactile feedback function, . The above-mentioned additional elements may be located in the non-display area and / or an external circuit connected to the connection interface.

Various portions of the flexible display device 100 may be bent along the curved line BL. The flexible display device 100 may be configured so that the flexible line BL can extend in a horizontal direction (e.g., the X direction in FIG. 1) or in a vertical direction (e.g., in the Y direction in FIG. 1) And can be bent in a combination of horizontal, vertical, and diagonal directions.

As mentioned, one or more edges of the flexible display device 100 may be bent away from the central portion 101 along the bend line BL. Although the bent line BL is shown to be positioned close to the edge of the flexible display device 100, the bent line BL may extend across the central portion 101, And may extend diagonally at one or more corners of the frame. Such a structure may be a display device in which the flexible display device 100 is a foldable display device or a display device on which folding is performed.

Since at least one portion of the flexible display device 100 can be bent, the flexible display device 100 can be defined as a substantially flat portion and a curved portion. A portion of the flexible display device 100 may be referred to as a central portion 101 that is substantially flat. A portion of the flexible display device 100 is bent at a predetermined angle, which portion may be referred to as the flexure portion 102. [ The bending portion 102 includes a bended section that actually bends at a predetermined bending radius.

The term " substantially flat " includes portions that are not perfectly flat. For example, the concave central portion 101a and convex central portion 101b depicted in Figure 2 may also be described as substantially flat portions in some embodiments. In Fig. 2, at least one bending portion 102 is present beside a concave central portion 101a or a convex central portion 101b, and is bent inward or outward at an angle to the bending axis along the bending line BL All. The bending radius of the bending portion 102 is smaller than the bending radius of the central portions 101a and 101b. In other words, the term " substantially flat portion " means a portion having a smaller curvature than an adjacent section.

The portion on one side of the bending line is positioned toward the center of the flexible display device 100 while the portion on the other side of the bending line is positioned toward the edge of the flexible display device 100 according to the position of the bending line BL . The portion of the flexible display device 100 facing toward the center may be referred to as a center portion and the portion of the flexible display device 100 facing the edge may be referred to as an edge portion. Although not always, the central portion of the flexible display device 100 may be substantially flat and the corner portion may be a curved portion. It should be noted that the substantially flat portion may also be located at the edge portion. And, in some configurations of the flexible display device 100, the flexion period may be between two substantially flat portions.

As mentioned above, when the non-display area is bent, the non-display area is not visible on the front surface of the display device, or is minimally visible. A part of the non-display area seen from the front side of the display device may be covered with a bezel. The bezel may be formed of a unique structure, or a housing or other suitable element. A portion of the non-display area seen on the front side of the display device may be hidden under an opaque mask layer such as black ink (e.g., a polymer filled with carbon black). This opaque mask layer may be provided on various layers (touch sensor layer, polarizing layer, cover layer, etc.) included in the flexible display device 100. [

In some embodiments, the curved portion of the flexible display device 100 may include a display area capable of displaying an image. This display area is hereinafter referred to as a second display area. That is, the curved line BL may be placed in the display area such that at least some pixels of the display area are included in the curved part.

Figs. 3A and 3B show the layout of the display area of the flexible display device 100 according to the embodiment of the present invention, respectively.

3A, the pixel matrix in the second display area can be extended continuously from the display area of the center part 101. [ Alternatively, in the shape of Fig. 3B, the second display region in the bending portion 102 and the display region in the central portion 101 can be separated from each other with the bending section interposed therebetween. The central portion 101 and the flexure portion 102 may be electrically connected by some of the components through one or more leads 120 laid across the flexure section.

The pixels of the second display region and the pixels of the central display region can be driven as if they are in the same matrix by a driving circuit (e.g., gate driver, data driver, etc.). At this time, it can be operated by the same driving circuits of the pixel of the second display area and the central display area. For example, the Nth row pixel of the central display area and the Nth row pixel of the second display area may be provided to receive a gate signal from the same gate driver. As shown in FIG. 3B, a bridge connecting part of the gate wiring crossing the bending section or the gate wiring of the two display areas may have a deformation reducing shape.

Depending on the function of the second display region, the pixels of the second display region may be driven separately from the pixels of the central display region. That is, the pixels of the second display area can be recognized by the driving circuit in an independent matrix separated from the pixel matrix of the display area. In this case, the pixels of the second display area can receive signals from at least one separate driving circuit different from the driving circuit that supplies signals to the pixels of the central display area.

Regardless of the shape, the second display region of the bent portion can function as the secondary display region of the flexible display device 100. [ The size of the second display area is not particularly limited. The size of the second display area may depend on the functions embedded in the electronic device. For example, the second display area can be used to provide images and / or characters such as graphical user interface (GUI), buttons, text messages, and the like. In some cases, the second display area may be used to provide light of various colors (e.g., status indications) of various colors, wherein the size of the second display area need not be as large as the display area in the center part.

4 is a cross-sectional view schematically showing a laminated structure of a flexible display device according to an embodiment of the present invention.

In FIG. 4, for convenience of explanation, the central portion 101 is substantially flat, and the curved portion 102 is shown as being at the edge of the flexible display device 100. As shown, the at least one bending portion 102 can bend outwardly from the central portion 101 with a bending angle? And a bending radius R with respect to the bending axis. The size of each bent portion 102 need not be the same. That is, the lengths from the bent line BL to the outer edge of the base layer 106 in each bent portion 102 may be different from each other. In addition, the bending angle? Around the bending axis and the radius of curvature R from the bending axis may be different for each bending portion 102.

In the example shown in Fig. 4, the right side of the bending portion 102 has a bending angle [theta] of 90 [deg.], And the bending portion 102 includes a section that is substantially planar. The bending portion 102 is bent at a larger bending angle? So that a portion of the bending portion 102 can be moved below the central portion 101, such as the left bending portion 102 of the flexible display device 100 have. Further, the bent portion 102 may be bent at a bending angle? Of 90 degrees or less.

In some embodiments, the curvature radius of curvature 102 may be between about 0.1 mm and about 10 mm, and preferably between about 0.1 mm and about 5 mm, or between about 0.1 mm and about 0.1 mm. 1 mm, or between about 0.1 mm and about 0.5 mm. In some embodiments, the radius of curvature in the flexure portion 102 may be less than 0.5 mm.

At least one support layer 108 may be provided at the bottom of the base layer 106 to increase the strength and / or rigidity at a particular portion of the flexible display device 100. For example, the support layer 108 may be provided on the lower surface of the central portion 101. The support layer 108 may not be provided in the bending section where greater flexibility is required. The support layer 108 may be provided on the curved portion 102 located below the central portion 101. Increasing the strength of a specific portion helps to accurately configure and arrange various components in the flexible display device 100. If the base layer 106 has greater elasticity than the support layer 108, the support layer 108 may contribute to suppress cracking in the base layer 106.

The base layer 106 and the support layer 108 may be made of a thin plastic film composed of a combination of polyimide, polyethylene naphthalate (PEN), polyethylene terephthalate, and other suitable polymers. Other suitable materials that may be used to form the base layer 106 and the support layer 108 include polymeric materials in combination with thin glass, dielectric foil metal foil, multilayer polymer, nanoparticles, or microparticles. A polymer film included therein, and the like. The supporting layer 108 provided in various portions of the flexible display device 100 need not all be the same material. For example, a plastic film can be used as the support layer 108 for the corner portion, while a thin glass layer is used as the support layer 108 for the central portion 101.

The thickness of the base layer 106 and the support layer 108 is also a consideration in the design of the flexible display device 100. In one aspect, if the base layer 106 has an excessive thickness, it is difficult for the base layer 106 to bend to a small radius of curvature. Also, the excessive thickness of the base layer 106 increases the mechanical stress on the components disposed thereon during bending. However, from another perspective, if the base layer 106 is too thin, it is too weak as a substrate to support the components disposed thereon.

Preferably, the base layer 106 has a thickness in the range of about 5 microns to about 30 microns, or preferably about 5 microns To about 16 < RTI ID = 0.0 > m. ≪ / RTI > The support layer 108 may have a thickness of from about 100 m to about 125 m, from about 50 m to about 150 m, from about 75 m to 200 m, from 150 m to 100 m.

In one embodiment, a polyimide layer having a thickness between about 10 [mu] m and about 16 [mu] m is used as the base layer 106 and a layer of polyethylene terephthalate (PET) having a thickness between about 50 [ ). In another embodiment, a polyimide layer having a thickness between about 10 microns and about 16 microns is used as the base layer 106, and thin glass having a thickness between about 50 microns and about 200 microns is used as the support layer 108. [ In another embodiment, a thin glass is used as the base layer 106, and the base layer 106 has a polyimide layer that functions as the support layer 108 to avoid breakage.

During manufacturing, some portions of the flexible display device 100 may be exposed to external light. The materials used to fabricate the components, or the components themselves, undergo unwanted state changes (e.g., threshold voltage transitions at the TFTs, etc.) due to light exposure during fabrication of the flexible display device 100. Some portions of the flexible display device 100 are excessively exposed to the external light as compared with other portions. This can cause display irregularities (eg mura, shadow defects, etc.). To minimize this problem, the base layer 106 and / or the support layer 108 may include one or more materials capable of reducing the amount of external light.

For example, the light blocking material is a chlorinated carbon black mixed with a constituent material (polyimide, other polymer) of the base layer 106. Thus, the base layer 106 may be formed of polyimide having a shade that provides a light shielding function. This base layer 106 can improve the visibility by reducing the reflection of external light incident on the front surface of the flexible display device 100. [

In order to reduce the amount of light incident from the rear surface of the flexible display device 100 (that is, the surface to which the support layer 108 is attached) instead of the base layer 106, . The constituent material of the support layer 108 may be mixed with one or more light blocking materials, similar to those described above. Further, both the base layer 106 and the support layer 108 may comprise one or more light-blocking materials. Here, the light shielding material used for the base layer 106 and the support layer 108 need not be the same.

Making the base layer 106 and the support layer 108 block out unwanted external light improves display uniformity and reduces reflection but can also cause alignment marks to accurately position the components, It may be difficult to recognize the alignment mark for performance. For example, since the arrangement of the layers is determined by comparing the outline of the overlapping portions, it is possible to accurately position the components on the base layer 106, or to align them during bending of the flexible display device 100 It can be more difficult. In addition, if the base layer 106 and / or the support layer 108 block an excessive range of optical spectra (i.e., visible light, ultraviolet light, infrared spectrum wavelengths), the debris or foreign matter in the flexible display device 100 May be a problem.

Thus, in some embodiments, the light blocking material included in the base layer 106 and / or the support layer 108 can be selected to have a specific polarization and / or light within a specific wavelength range used in one or more manufacturing / . As an example, the support layer 108 may pass light (e.g., UV, IR) used in the quality inspection and / or alignment process and block light in the visible light wavelength range. In the limited range of wavelengths, when the base layer 106 contains a light shielding material. Which helps to reduce the non-uniformity problem of the display device caused by the shading caused by the printed circuit film attached to the base layer 106. [

The base layer 106 and the support layer 108 may together perform blocking or passage of certain types of light. For example, the support layer 108 may change the polarization of light so that the light does not pass through the base layer 106. As such, certain types of light may pass through the support layer 108 for various purposes during fabrication of the flexible display device 100, but may also be applied to components disposed on the opposite side of the base layer 106 It can not pass through the base layer 106 without unnecessary influence.

A backplane of the flexible display device 100 is implemented on the base layer 106. [ In some embodiments, the backplane of the flexible display device 100 is implemented with a TFT using a low temperature poly silicon (LTPS) semiconductor layer as an active layer. In one example, the pixel circuit and drive circuitry (e.g., GIPs) on the base layer 106 may be implemented with NMOS LTPS TFTs. In another example, the backplane of the flexible display device 100 may be implemented with a combination of an NMOS LTPS TFT and a PMOS LTPS TFT. For example, the driving circuit (e.g., GIP) on the base layer 106 may include one or more CMOS circuits to reduce the number of wires for controlling the scan signals on the gate lines.

In some embodiments, the flexible display device 100 may employ various kinds of TFTs to implement driving circuits in a pixel circuit in a non-display region and / or a display region. That is, in order to implement the backplane of the flexible display device 100, a combination of an oxide semiconductor TFT and an LTPS TFT can be used. In the backplane, the type of the TFT may be selected according to operating conditions and / or TFT requirements in the associated circuit

LTPS TFTs generally exhibit excellent carrier mobility even in a small profile, making them suitable for implementing integrated drive circuits. This superior carrier mobility makes the LTPS TFT ideal for components requiring fast operating speeds. Despite the advantages mentioned above, the initial threshold voltage may differ between the LTPS TFTs due to the grain boundary of the polysilicon semiconductor layer.

A TFT employing an oxide-based semiconductor layer such as an IGZO (indium-gallium-zinc-oxide) semiconductor layer (hereinafter referred to as an oxide TFT) differs in many aspects from the LTPS TFT. Despite the low mobility compared to the LTPS TFTs, the oxide TFTs are generally more advantageous in power efficiency than the LTPS TFTs. The low leakage current of the oxide TFT in the off state lasts longer in the active state. This can be an important advantage in driving the pixel at a reduced frame rate when a high frame rate is not required to drive the pixel.

As an example, the flexible display device 100 may have a characteristic in which all or a part of pixels of the display area are driven at a reduced frame rate under certain conditions. In this setup, the pixel may be refreshed at a reduced rate depending on the content displayed on the flexible display device 100. [ Also, some of the display areas displaying stopped image data (e.g., user interface, text) can be refreshed at a lower rate than the display areas of other parts displaying fast changing image data (e.g., movies) have. A pixel driven with a reduced refresh rate may increase the blank period during which the data signal is not provided to the pixel. This will minimize the power consumed by providing the same image data to the pixels. In this embodiment, some TFTs implementing the pixel circuit and / or the driving circuit may be formed of oxide TFTs to minimize the leakage current during the blank period. In the pixel circuit and / or the driving circuit, By reducing the current, the pixel can achieve a more stable brightness level even when the display is refreshed at a reduced rate.

Another characteristic of the oxide TFT is that the initial threshold voltage change between the transistors does not suffer as much as the LTPS TFT. This aspect can be a significant advantage when the size of the flexible display device 100 increases. Also, the threshold shift between the LTPS TFT and the oxide TFT under bias stress is different.

In view of the above-mentioned characteristics of the LTPS TFT and the oxide TFT, some embodiments of the flexible display device 100 can be applied to a combination of an LTPS TFT and an oxide TFT in one backplane. Particularly, in some embodiments of the flexible display device 100, an LTPS TFT is employed to implement a driving circuit (e.g., GIP) in a non-display region, and an oxide TFT is used to implement a pixel circuit in a display region . Because of the excellent carrier mobility of the LTPS TFT, the driving circuit implemented in the LTPS TFT can operate at a higher speed than the driving circuit implemented with the oxide TFTs. In addition, a drive circuit more integrated by the LTPS TFT can be provided, whereby the size of the non-display area can be reduced. Due to the excellent voltage holding ratio of the oxide TFT used in the pixel circuit, the leakage current in the pixel can be reduced. It also allows the pixel to be driven at a specific frame of the display area or at a reduced frame rate under predetermined conditions (e.g. when displaying still images) while minimizing display defects caused by leakage currents

In some embodiments, while the pixel circuit is implemented as an oxide TFT, the driver circuit may be implemented with a combination of an N-type LTPS TFT and a P-type LTPS TFT. For example, N-type LTPS TFTs and P-type LTPS TFTs can be used to implement CMOS gate drivers (e.g. CMOS GIP, data drivers). On the other hand, an oxide TFT can be applied to at least some portions of the pixel circuit. Unlike the GIP, which is formed entirely of P-type or N-type LTPS TFTs, the gate output signal from the CMOS gate driver can be controlled by a DC signal or a logic high / low signal. As a result, the gate line is more stably controlled during the blank period, and current leakage from the pixel circuit and the inadvertent activation of the pixel are suppressed.

The CMOS gate driver or inverter circuit on the backplane may be implemented with a combination of an LTPS TFT and an oxide TFT. For example, P-type LTPS TFTs and N- type oxide TFTs can be used to implement CMOS circuits. Further, the pixel circuit of the display area can be implemented using both the LTPS TFT and the oxide TFT. In order to eliminate the bias remaining at the node between the oxide TFTs and to minimize the bias stress (e.g., PBTS, NBTS) when the two kinds of TFTs are applied to the pixel circuit and / or the driving circuit, the LTPS TFT It can be strategically placed inside the circuit. Additionally, a TFT connected with a storage capacitor in the circuit may be formed of an oxide TFT to minimize leakage current.

An organic light emitting diode (OLED) layer is disposed on the base layer 106. The organic light emitting device layer 150 includes a plurality of OLED elements. The OLED element is controlled by a pixel circuit and a driving circuit implemented on the base layer 106, and another external driving circuit connected to the connection interface on the base layer 106. The OLED layer includes a layer of an organic light emitting material that emits light of a specific color (e.g. red, green, blue). In some embodiments, the layer of organic emissive material may have a laminated structure capable of emitting white light (essentially a combination of light of different colors).

The sealing layer 104 is provided to protect the organic light emitting device layer 150 from air and moisture. The encapsulant layer 104 may comprise several layers of material to reduce the penetration of air and moisture. In some embodiments, the encapsulation layer 104 may be provided in the form of a thin film.

The flexible display device 100 may include a polarizing layer 110 to control display characteristics (e.g., external light reflection, color accuracy, brightness, etc.). In addition, the cover layer 114 may be used to protect the flexible display device 100.

An electrode may be formed on one side of the cover layer 114 and / or on at least one side of the polarizing layer 110 to sense the user's touch input. If desired, a separate layer (hereinafter referred to as a touch sensor layer 112) with touch sensing electrodes and / or other components associated with touch input sensing may be provided within the flexible display device 100. The touch sensing electrode (e.g., the touch driving / sensing electrode) may be formed of a conductive material such as indium tin oxide, a carbon based material such as graphene, a carbon nanotube, a conductive polymer, or a hybrid material made of a mixture of various conductive / non- May be formed of a transparent conductive material. In addition, a metal mesh such as an aluminum mesh or a silver mesh may be used as the touch sensing electrode.

The touch sensor layer 112 may comprise one or more modified dielectric materials. One or more electrodes may be interfaced with or in proximity to the touch sensor layer 112 and read signals that measure electrical changes on the electrodes. The measurement is analyzed and the amount of pressure input to the flexible display device 100 is evaluated at several bells.

In some embodiments, the touch sensing electrode can be utilized to identify the position of the user input and to evaluate the pressure of the user input. The touch input position determination and the touch pressure measurement may be performed by measuring a capacitance change of the touch sensing electrode on one side of the touch sensor layer 112. The touch sensing electrodes and / or other electrodes may be used to measure a signal indicative of the pressure on the flexible display device 100 by a touch input. This signal is obtained from the touch-sensitive electrode at the same time or at a different timing with the touch signal.

The strain material contained in the touch sensor layer 112 may be an electroactive material and the amplitude and / or frequency of the material is controlled by electrical signals and / or electric fields. Such deformable materials may be piezo ceramic, Electro-active-polymer, and the like. Accordingly, the touch sensing electrode and / or the separate electrode may activate the deformable material to bend the flexible display device 100 in a desired direction. Additionally, the electro-active material may be activated to vibrate at a desired frequency to provide tactile and / or texture feedback on the flexible display device 100. The flexible display device 100 employs a plurality of electro-active materials so that bending or vibration of the flexible display device 100 can be provided at the same time or at different timings. This combination can be used to create a sound wave from the flexible display device 100. [

Some components may make it difficult to bend the flexible display device 100 along the bending line BL. Some components, such as the support layer 108, the touch sensor layer 112, the polarization layer 110, etc., may add strength to the flexible display device 100. In addition, the thickness of the components moves the neutral plane of the flexible display device 100, such that some of the components create a greater bending stress than the other elements.

In order to improve the bending and reliability of the flexible display device 100, the configuration of the components in the bent portion 102 is different from that in the central portion 101. [ Some of the components present in the central portion 101 are not disposed in the bending portion 102, or are provided in different thicknesses. The other portions of the support layer 108, the polarizing layer 110, the touch sensor layer 112, the color filter layer, and / or the flexible display device 100, which interfere with the bending of the flexible display device 100, have. If the bend portion 102 is not visible or accessible to the user, such components are not required.

In order to provide information to the user, a second display area is in the bend portion 102, but some of the components are not needed depending on the use and / or form of the information provided by the second display area . For example, if the second display area only emits color or displays text or a simple GUI only in a light / dark combination (e.g., black text or icon on a white background), the polarizing layer 110 and / It is unnecessary for the bent portion 102. If the touch function is unnecessary, the touch sensor layer 112 may not exist in the bent portion 102. The flexure portion 102 may include a touch sensor layer 112 and / or a layer of electrically-activating material, if necessary, although no auxiliary display region for displaying information is provided in the flexure portion 102. [

Since the flexion zone is most affected by bending stresses, various stress reduction structures are applied to the components in the flexion zone. To this end, some of the components in the central portion 101 are not present in at least a portion of the curved portion 102. The bending section is freed from the respective components by selectively removing the component in the bending section so that the separation between the central section 101 and the bending section 102 is made.

4, the supporting layer 108 in the central portion 101 and the supporting layer 108 in the curved portion 102 are arranged in a manner such that the supporting layer 108 is not present in the curved section 102b They can be separated from each other. Instead of the support layer 108 attached to the base layer 106, a rounded support member 116 may be disposed in the lower bending region of the base layer 106. Various other components, for example, the polarizing layer 110, the touch sensor layer 112, and the like may not exist in the bending section. Removal of the components may be accomplished by means of wet etching, dry etching, scribing, or any other suitable method. Instead of cutting or other removal, a segment of the component can be formed in a selected portion (e.g., a central portion and a bend portion) so that there is no corresponding component in the bend section. Instead of being completely removed from the flexure portion 102, some components may have a flexure pattern along a portion of the flexure line and / or the flexure region to reduce bending stress.

5 is a top view and a cross-sectional view of a bending pattern according to an embodiment of the present disclosure.

The bending pattern 300 may be applied to several components. The bending pattern 300 may be used for the support layer 108, the polarizing layer 110, the touch sensor layer 112, and the like.

The flexible display device 100 may utilize one or more bending patterns 300. The number of bending patterns used in the parts and the shape of the bending pattern are not limited. If desired, the depth of the pattern 300 may be such that it completely penetrates the part but only partially penetrates each layer. Not only a passivation layer covering a conductive line but also a buffer layer between the base layer 106 and the TFT may be provided with a bending pattern to reduce bending stress.

As mentioned above, the support layer 108 is not present in the bending section for easy bending of the base layer 106. However, due to the absence of the support layer 108, the curvature of the bending section is easily deformed by an external force. In order to support the base layer 106 and maintain the curvature of the bending section, the flexible display device 100 may include a support member 116, which may be referred to as a mandrel have. The support member 116 shown in Fig. 2 includes a body portion and an end portion. The base layer 106 and the support member 116 are disposed so that a rounded end portion is located on the lower surface of the base layer 106 corresponding to the bending section.

In embodiments where the flexure portion 102 is at the edge of the flexible display device 100, the support member 116 may be located at the edge of the flexible display device 100. [ In this setting, a portion of the base layer 106 surrounds the end of the support member 116 and is positioned on the lower surface of the support member 116, as shown in FIG. The various circuits and components (driving IC, connecting interface with connecting chip-on-flex (COF), printed circuit board, etc.) in the non-display area are connected to the base layer 106 ). ≪ / RTI > In this way, even if it is not a flexible part, it can be positioned below the display area.

The support member 116 may be formed of a plastic material such as polycarbonate (PC), polyimide (PI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET) The strength of the support member 116 made of the plastic material can be controlled by additives that increase the thickness and / or strength of the support member 116. The support member 116 may be formed in a desired color (e.g., black, white, etc.). The support member 116 may be made of a hard material such as glass, ceramics, metal, or a combination thereof.

The size and shape of the end portion of the support member 116 may vary depending on the desired minimum curvature in the bending section. In some embodiments, the thickness of the end portion and the body portion may be substantially the same. In another embodiment, the planar body portion may be thinner than the end portion. With the thinner body portion, the support member 116 can support the bending section 102b while avoiding an unnecessary increase in the thickness of the flexible display device 100. [

The bending section is supported by the end portion of the support member 116 so that the body portion extending toward the central portion 101 of the flexible display device 100 need not extend to the display region. If the body portion can extend to below the display region for various reasons, the length of the body portion toward the opposite end from the end portion is sufficient to reach the surface region for supporting the support member 116.

An adhesive layer 118 may be provided on the surface of the support member 116 to secure the support member 116 in the flexible display device 100. [ The adhesive layer 118 may include a pressure-sensitive adhesive, a foam-type adhesive, a liquid adhesive, a light-cured adhesive, or other suitable adhesive material. have. In some embodiments, the adhesive layer 118 is formed of, or includes, a material that can be compressed, and may function as a cushioning material for portions that are adhered by the adhesive layer 118. In one example, May be compressible. The adhesive layer 118 may be formed in a multi-layer structure, which includes a buffer layer (e.g., polyolefin foam) between the upper and lower layers of the adhesive material layer.

The adhesive layer 118 may be located on at least one of the upper and lower surfaces of the body portion of the support member 116. When the bent portion 102 of the flexible display device 100 covers the end portion of the support member, the adhesive layer 118 contacts the lower surface (i.e., the surface facing the rear surface) of the body portion and the upper surface ) Can be provided to both. If necessary, an adhesive layer 118 may be provided between the end of the support member 116 and the inner surface of the base layer 106.

During flexing, a portion of the flexible display device 100 on one side of the support member 116 may be pulled toward the support member 116 and the base layer 106 may be pulled toward the top And the bottom edge. The height of the adhesive layer 118 and the height of the support layer 108 between the support member 116 and the base layer 106 are set such that the uppermost edge of the end portion and the surface of the body portion where the adhesive layer 118 is located Lt; / RTI > In other words, the height of the space resulting from the difference in thickness between the end portion and the body portion is smaller than or equal to the sum of the thicknesses of the support layer 108 and the adhesive layer 118.

Depending on the shape of the support member 116, the thickness of the adhesive layer 118 on the upper and lower surfaces of the body portion may be different. For example, the body portion thinner than the end portion may not exist at the center of the end portion. In this case, the space on one side of the support member 116 may be larger than the space on the opposite side.

In another example, the lowermost edge of the end portion is inside the bottom line of the body portion, and only a space is formed on one side of the body portion. In this case, the adhesive layer 118 on one side of the body portion may be thicker than the opposite side.

6A, 6B, and 6C are schematic cross-sectional views illustrating exemplary arrangements of components in various embodiments of the flexible display device 100. As shown in FIG.

In one configuration, in FIG. 6A, the thickness of the rounded end portion and the elongated body portion of the support member 116A may be substantially the same. The support member 116A may be formed of a plastic material. The support member 116A may be formed of a folded thin metal sheet (e.g., SUS). At this time, the folded edge of the metal sheet can function as the rounded end of the support member 116A. Even when the metal sheet is used to form the support member, the end portion can be thicker than the body portion. For example, pressure can be applied to a portion of the folded metal sheet such that the body portion is thinner than the folded edge.

In Fig. 6A, an adhesive layer 118A is shown applied to the top, bottom, and round end surfaces of the support member 116A. The adhesive layer 118A has a substantially uniform thickness on the surface of the support member 116A because the thickness of the support member 116A is substantially the same in the thick round portion and the trunk portion. However, the adhesive layer 118A may be thinner or thicker at selected portions of the support member 116A.

As another example, the thickness of the elongated body portion of the support member 116 may be thinner than the rounded end portion. In this case, if the support member 116B has a flat bottom as in Fig. 6B, the lower surface of the trunk portion is aligned with the lowest edge of the end portion. In this exemplary configuration, the support member 116B may be formed of the above-mentioned plastic material (e.g., polycarbonate or the like) or a combination thereof. The adhesive layer 118B provided on the upper surface of the body portion is thicker than the adhesive layer 118B provided on the lower surface of the body portion. The adhesive layer 118B on the upper surface of the body portion may include a buffer layer, while the adhesive layer 118B on the lower surface is not.

6, neither the upper nor the lower surface of the body portion of the support member 116C is in line with the highest / lowest edge of the rounded portion. The support member 116C may be formed of the above-mentioned plastic material (for example, polycarbonate or the like) or a combination thereof. In this example, the body portion is not symmetrical (i.e., closer to the lowermost corner of the rounded portion), and the adhesive layer 118C on the upper surface of the body portion is thicker than the adhesive layer 118C on the lower surface

While the adhesive layer 118B on the lower surface is not, the adhesive layer 118C on the surface above the body portion may contain the buffer filler described above.

6A to 6C, the support layer 108 above the support member 116 may extend beyond the encapsulation layer 114 toward the bending section. In other words, a portion of the base layer 106 toward the bending section is not covered by the encapsulation layer 114, but the support layer 108 is provided thereunder. The remaining length of the support layer 108 may help maintain the curvature at the bending section. The edge of the lower support layer 108 of the support member 116 can move away from the bending section. In some embodiments, a flange may be provided at the edge of the support layer 108 towards the bending section. The rim may be further extended toward the bending section as shown in Fig. 6A. In one example, the rim may be made by cutting or patterning so that the support layer 108 has sharp edges. As another example, the rim may be provided by stacking at least two support layers so that their edges are brushed together. Although omitted in Figs. 6B and 6C, the rim may also be provided in the corresponding embodiment.

The configurations described in Figures 6A through 6C are exemplary only. An adhesive layer having the same thickness can be provided on the upper and lower surfaces of the support member regardless of the position of the body portion. And the adhesive layer on the upper or lower surface of the support member may comprise a buffer layer.

A plurality of leads are included in the flexible display device 100 for electrical connection between the various components. Circuits fabricated in the display area and the non-display area can provide various functions by transmitting various signals through one or more wires. Several conductors may be used for interconnections between the circuitry and / or other components in the central portion and the flexure portion.

A conductive line refers to a conductive path for transferring electrical signals, power, and / or voltage from one point to another point within the flexible display device 100. The lead may include a gate line / data line for transmitting a signal to a pixel circuit of a display area in a display drive circuit (e.g., a gate driver, a data driver) of a non-display area, and a source / drain electrode of the TFT. Similarly, conductors such as a touch sensing electrode, a pressure sensing electrode, and a fingerprint sensing electrode may provide a signal for touch input sensing or fingerprint recognition on the flexible display device 100. Also, And can provide interconnections between parts of the second display area.

The leads of the flexible display device 100 must be carefully designed to meet electrical / non-electrical requirements. For example, a conductor may have a certain minimum resistance level, which may vary depending on the type of signal to be transmitted through the conductor. Some conductors may be sent from the substantially flat portion to the bent portion. These leads should be flexible enough to maintain mechanical / electrical robustness. To this end, some leads of the flexible display device 100 have a multi-layered structure.

Figures 7A and 7B illustrate an exemplary laminated structure of a multi-layer structure conductor.

Referring to FIG. 7A, the conductive line 120 has a multi-layer structure in which the first conductive layer 122 is sandwiched between the second conductive layers 124. The first conductive layer 122 may be formed of a material having a lower electrical resistance than the second conductive layer 124. The first conductive layer 122 includes, but is not limited to, materials such as copper, aluminum, a transparent conductive oxide, and other flexible conductors.

The second conductive layer 124 is formed of a conductive material exhibiting a sufficiently small ohmic contact resistance when deposited over the first conductive layer 122. The low contact resistance between the conductive layers in the multi-layer conductor 120 is not the only factor to consider when selecting the conductive layer material. The conductive material 120 must meet the minimum mechanical strength requirements (e.g., Young's modulus) while meeting the stringent electrical and thermal requirements (e.g., resistance, heat, etc.) The conductive layer 124 should all be formed of a material that exhibits sufficient flexibility.

Thus, in some embodiments, at least some of the conductors 120 of the flexible display device 100 may be formed of two or more layers selected from aluminum (Al), titanium (Ti), molybdenum (Mo), and copper . Examples of such combinations include an aluminum layer (Ti / Al / Ti) sandwiched between titanium layers, an aluminum layer (Mo / Al / Mo) between upper and lower molybdenum layers, a copper layer (Ti / Cu / Ti) , A copper layer (Mo / Cu / Mo) between upper and lower molybdenum layers, and the like. Of course other conductive materials can also be used as the first / second layer.

An electronic apparatus that employs the flexible display apparatus 100, such as a wearable electronic apparatus or an underwater electronic apparatus, can expose the flexible display apparatus 100 to a humid environment. In some cases, moisture can reach the wire 120. Unlike metals and alloys have different electrode potentials, and when two or more are in contact with the electrolyte, one metal behaves as an anode and the other metal acts as a cathode. The potential difference between the non-mimic metal promotes the corrosion of the anode member, which may be the first conductive layer 122 (e.g., the Al layer of the Ti / Al / Ti stack) of the multilayer wire 120. The anode metal melts to become an electrolyte and accumulates on the cathode metal.

The surface that exposes both the first conductive layer 122 and the second conductive layer 124 when using the multi-layer wire 120 described above may be a starting point for galvanic corrosion. 7B, the outer surface of the first conductive layer 122 is surrounded by the second conductive layer 124. In some embodiments of the flexible display device 100, This shape minimizes the loss of the first conductive layer 122 by galvanic corrosion by preventing the electrolyte from contacting both the first conductive layer 122 and the second conductive layer 124

The multilayer wire 120 may be fabricated by depositing a material (e.g., Al) for the first conductive layer 122 over the second conductive layer 124 (e.g., Ti). Here, the first conductive layer The second conductive layer 124 under the second conductive layer 124 may have a greater width. Etch blocking materials are formed on the two layers and etched (e.g., dry etch, wet etch, etc.) to form leads in the desired wiring pattern. After the etch stop material is stripped, a second conductive layer 124 (e.g., Ti) is deposited over the structure (i.e., Ti / Al). The width of the second conductive layer 124 stacked on the first conductive layer 122 is larger than the width of the first conductive layer 122 so as to cover the outer surface of the first conductive layer 122 . The following etching and etch stop material removal steps are performed to form a multilayered wire according to the desired wire layout design. The above-described multi-layer wire forming process is only exemplary. Thus, some processes may be added and / or omitted in the fabrication of the multi-layer conductors.

The trace design of the leads is an important factor that can affect the electrical / mechanical properties of the leads. To meet the electrical / mechanical requirements, one part of the wire may be configured differently from the other part. A structure for controlling the bending stress is provided in one portion of the conductor at or near the bending section of the flexible display device 100. [

The adjustment of the bending stress of the insulating layer near the conductor is as important as the deformation of the conductor itself. Various insulating layers, such as a buffer layer 126, a passivation layer 128, a gate insulating layer (GI), and an interlayer insulating layer (ILD), located above and / or below the lead 120 may include inorganic materials. A layer formed of a material, such as a silicon oxide layer or a silicon nitride layer, is generally more prone to crack than a metal layer of a conductor. Even when the wires have sufficient flexibility to withstand bending stresses without cracking, cracks in the insulating layer can propagate to the wires, creating a poor electrical connection.

As a wiring design that reduces the bending stress of the leads, some of the insulating layers above and / or below the leads 120 may be patterned to minimize cracking. Various insulating layer patterning techniques such as wet etching and / or dry etching may be used to make the shape of the insulating layer corresponding to the wiring structure. Elimination of the insulating layer, especially the insulating layer based on the inorganic material around the conductor, not only reduces the chances of cracking but also eliminates its propagation path. For convenience of description, the arrangement of the insulating layer covering at least a part of the lead 120 and the lead 120 will be referred to as " wire trace " hereinafter.

As mentioned, the design of insulating layers covering conductors and conductors plays an important role in increasing the robustness of the interconnection structure. Various factors, from thickness and width to the angle of unfolding of the wire segments with respect to the respective bending directions, are associated with the design of the wiring structure. In addition, many other factors related to conductor 120 and insulation layer placement are specially tuned based on the installation and orientation of the wiring.

The more the direction in which the wiring structure extends, the more the tangent vector of the curvature is, the greater the deformation of the wiring due to bending stress. In other words, if the length of the wiring piece parallel to the tangent vector of the curvature is reduced, the wiring structure will withstand the bending stress more. Regardless of the direction in which the wiring structure extends, there is always a portion measured in the bending direction within the wiring structure. However, by applying the deformation reduction design to the wiring structure, the length of each successive measurable portion (i.e., piece) aligned in parallel to the bending direction can be reduced.

Figure 8 shows some examples of strain relief wiring design.

One or more of the sine-wave, square-wave, saw tooth, wave, and shaded shapes shown in Fig. 8 can be used for the wiring structure. Applying such deformation reduction design increases the wiring portion aligned in the oblique direction to the tangent vector of the curvature. This limits the length of the wire segments extending in a straight line parallel to the bending direction.

It is important that the length of the insulating layer aligned with the tangent vector of the curvature is also minimized since cracks in the wiring structure due to bending of the flexible display typically start with an inorganic insulation layer. Within the deformation reduction design of a wire, the width and shape of the wire as well as the width of the patterned inorganic insulation layer that meets the surface of the wire must be kept to a minimum.

The strain relief layout design shown in Fig. 8 is merely exemplary, and other layout designs for reducing wire fragments parallel to the flexure direction in various embodiments of the flexible display device 100 may be used. And, some wiring structures can employ a deformation reduction layout design that is different from other wiring structures in the flexible display device 100, depending on electrical and / or mechanical requirements. For example, the deformation reduction layout design used for the data signal line may be different from the deformation reduction layout design of the power supply line.

In order to further improve the robustness, the wiring structure can use a layout design that is repeatedly divided and gathered at specific intervals. In other words, the interconnect structure includes at least two sub-traces so that the interconnecting links form interconnects that resemble an interconnected chain. The angles divided and gathered define the shape of each link, and the shape of each link limits the length of the wire segments that can be measured in a straight line parallel to the direction of flexion.

Referring to FIG. 9A, a lead 120 includes a sub-line A and a sub-line B that are divided and gathered at each joint X. In FIG. A part of the sub-line A is extended by a predetermined distance in the first direction at an angle away from the tangent vector of the curvature, and another part of the sub-line A is extended between the first part X (1) and the second part X Extends in the second direction. The sub-line B is bent in a similar manner to the sub-line A, but in the opposite direction with respect to the tangent vector of the curvature. The distance and direction in which the sub-wires are arranged between two adjacent nodes define the shape and size of the link in the chain as well as the open area surrounded by the sub-wires. In this example, the shape of the lead 120 between the first node X (1) and the second node X (2), i.e., the link, is a diamond shape having an open region surrounded by the sub- Along with the additional node X, the lead 120 forms a chain of diamond shaped links, which can be referred to as diamond wirings.

Compared to the undivided strain relief wiring design shown in FIG. 8, the strain relief wiring design shown in FIG. 9A can provide significant advantages in electrical characteristics. For example, a wiring structure with a split / group wiring design has a much lower electrical resistance than a wiring structure with a deformation reduction design of the acid wiring, sinusoidal wiring, or other single lead type of FIG. In addition, the secondary wiring can function as a secondary passage when one wiring is damaged.

The insulating layer covering the surface of the lead 120 is also patterned with a layout design corresponding to the wiring structure of the lead 120. In this case, the open area surrounded by the sub-lines A and B does not include an inorganic insulating layer, Lt; RTI ID = 0.0 > and / or < / RTI > At this time, the length of the insulating layer which can be measured in a straight line parallel to the bending direction can be limited so as to reduce cracking and propagation.

Various additional factors should be considered for deformation abatement design based on multiple sub-wires. The length of the subwiring between the split / gather angle and the two adjacent nodes X provides an offset for the inorganic insulating layer at the outer vertex where the node X and the subwiring change direction between the two adjacent nodes X. Should be. In other words, the open area surrounded by the secondary wiring between the two nodes X should have a size and shape that minimizes the length in which the inorganic insulating layer structure of the wiring extends parallel to the bending direction.

9A, the buffer layer 126 and the protective layer 128 covering the lead 120 are spaced from the outer structure (i.e., the outer edge) of the lead 120 by a predetermined margin And patterned. There is no insulating layer in the open area FA2 surrounded by the sub-lines A and B other than the remaining insulating layer covering the conductor 120 with a predetermined margin. Thus, the arrangement structure of the insulating layer is formed corresponding to the layout design of the lead 120. [ The length of the open area without insulating layer, measured in the direction perpendicular to the bending direction, Is larger than the width of the inorganic insulating layer structure at the node X measured in the same direction. In this setup, the open area FA2 surrounded by the sub-lines A and B as well as the area beside the node X may have no free insulating layer or have a reduced number of inorganic insulating layers.

9A, the insulating-free area FA1 prevents the insulating layer of the sub-wiring A and the sub-wiring B between the two nodes X (1) and X (2) from extending in a continuous straight line. Likewise, the insulating layer-free area FA2 prevents the insulating layer between the two nodes X (1) and X (2) from expanding into a continuous straight line. Thus, the length of each array of insulation layer arrays aligned to the tangent vector of curvature is minimized. Reducing the length of each of the insulating layer alignment pieces aligned with respect to the tangent vector of curvature is obtained by reducing the width of the conductive line 120 and the margin of the insulating layer beyond the edge of the conductive line 120.

The decrease in the width of the conductor 120 in the single conductor strain relief wiring design described in Fig. 8 is limited because the decrease in the conductor width makes the electric resistance extremely large as compared with the specific use in the flexible display device 100. [ However, in the split / gather wiring design of Figure 9a, the width of the conductor 120 and the insulation layer structure can be reduced while meeting the required electrical properties.

The larger split / gather angle with respect to the direction of deflection of the sub-wiring greatly reduces the length of the conductor 120 and insulation layer structure that extend along the tangent vector of curvature. Therefore, by selectively increasing the division / gathering angle of the sub-lines in the high flexural stress region, the possibility of cracking in the wiring structure is lowered.

The split angle of the subwiring can affect the distance between two adjacent nodes X in the diamond wiring design. The distance between the nodes X does not need to be uniform across the entire wiring. The interval at which the wiring is divided and gathered can be changed in one wiring based on the degree of bending stress applied to a specific portion of the wiring structure. The distance between the nodes X at a particular portion of the wiring toward a region where a larger bending stress is applied (for example, a region having a smaller bending radius, a region having a larger bending angle) may be gradually reduced. Conversely, when facing a region where smaller bending stress is applied, the distance between the nodes X may gradually increase.

Even with strain relief wiring design, inevitable bending stress remains at some point (i.e., stress point) in the wiring. The position of the stress point depends largely on the bending direction and the shape of the wiring. Thus, for a given bending direction, the wiring structure can be designed such that the remaining bending stress is concentrated at the desired portion. Knowing the stress points in the wiring allows the wiring structure to be able to withstand the bending stress longer, and the crack-stopping region can be provided at the stress point.

9A, when the wiring structure having the diamond wiring design is bent in the bending direction, the bending stress tends to concentrate at the angular vertex (i.e., the apex of each diamond-shaped link) Point B, respectively. As described above, the cracks start and enlarge between the inside and the outside of the wiring structure. For example, at the stress point A, the crack may start from the inner wire 120 (IN) and proceed to the outer wire 120 (OUT). Similarly, at the stress point B, the cracks may start at the outer wire 120 (OUT) and proceed to the inner wire 120 (IN).

Thus, at the stress point A, the width of the lead 120 can increase selectively to serve as a crack-stop region. 9A, the widths WA, WB of the lead 120 at the stress points A and B, measured perpendicular to the bending direction, are the width (W) of the lead 120 at the portion between the stress points A and B, Lt; / RTI > The additional width at the stress point can make the lead 120 longer lasting until the crack at the stress point becomes larger and is completely cut off.

The length of the continuous portion of the insulating layer structure aligned in the bending direction should be kept to a minimum. Increasing the width of the conductor 120 at stress points A and B will inevitably increase the width of each insulating layer structure, which leads to a longer insulating layer structure aligned parallel to the direction of bending.

Thus, in some embodiments, the width of the lead 120 measured in a direction normal to the tangent vector of curvature at the stress point A is between about 2.5 micrometers (μm) to about 8 μm, preferably about 3.5 μm to about More preferably between about 4.5 [mu] m and about 8.5 [mu] m, and even more preferably about 4.0 [mu] m. The width of the lead 120 at the stress point B should be kept close to the width of the lead 120 at the stress point A. [ Thus, at the stress point B, the width of the lead 120 can be between about 2.5 μm and about 8 μm, preferably between about 3.5 μm and about 6 μm, more preferably between about 4.5 μm and about 8.5 μm , And even more preferably about 4.0 [mu] m. The width of the lead 120 at the stress point B may be longer than the width at the stress point A because the subwiring A and the subwiring B converge at the stress point B. [

In some embodiments, one of the inner wire 120 (IN) and the outer wire 120 (OUT) may not be kinked as sharp as other wires at the stress point A to minimize the occurrence of cracking on both sides. In the embodiment illustrated in FIG. 9A, the inner wire 120 (IN) is more sharply deflected than the outer wire 120 (OUT) at the stress point A. However, in other embodiments, the outer wire 120 (OUT) may be more sharply deflected than the inner wire 120 (IN) at the stress point A. In both cases in the description of Figure 9A, the less sharpened wire can be rounder than the straight wire like the outer wire 120 (OUT). At the stress point A, both the inner wire 120 (IN) and the outer wire 120 (OUT) can be rounded.

The wiring structure can be divided into a larger number of sub-wirings and can be a continuous link arranged like a grid shape. As an example, the wiring structure may be configured as a spider web of diamond wiring as shown in Fig. 9B. This wiring design is particularly useful when the wiring carries a common signal at a plurality of points, or when the wiring requires very low electrical resistance. For example, in the flexible display device 100, the VSS line and the VDD line are particularly useful for the line May have the grid wiring structure when they are arranged to cross the bending section. None of the number and shapes of the secondary wirings in the grid wiring structure is limited by the example of Fig. 9B.

In some embodiments, the width of the grid may be reduced or stretched between the ends of the flexible display device 100. Further, the grid wiring structure shown in Fig. 9B may converge again to form the diamond wiring in Fig. 9A or to form strain-relieved wiring without division. In some cases, the size of each diamond-wire in the grid-shaped wire structure may be larger than the size of each diamond wire in the diamond wire chain to reduce resistance

The wiring structure having the deformation reducing wiring design may require a larger routing area in the flexible display device 100 because of the portion bent away from the bending direction. In the embodiment in which the non-display area at the edge of the flexible display device 100 is bent, increasing the routing area to accommodate the wiring structure increases the size of the non-display area to be hidden.

Therefore, the wiring structure to which the deformation reduction design is applied should be arranged at closely spaced intervals between adjacent wirings. For example, two adjacent interconnects with strain relief designs may include non-linear sections with convex sides and concave sides, respectively. The two adjacent wirings may be arranged so that the convex side of the nonlinear section of the first wiring structure is located next to the concave side of the nonlinear section of the second wiring structure. Since the distance between the two wirings is limited by the shape and size of the wiring structure, the nonlinear section in the deformation reduction design of the first wiring structure can be larger than the nonlinear section in the deformation reduction design of the second wiring structure. Of course, one of the first wiring structure and the second wiring structure may have another strain reduction design to better accommodate the non-linear section of the other wiring structure.

For example, two or more wiring structures arranged side by side may each be subjected to strain reduction design, and each wiring structure may have a plurality of indented sections and a distended section. In such a case, the expansion zone of one wiring structure may be arranged to lie next to the shrinkage zone of the adjacent wiring structure.

Figure 10 shows an exemplary arrangement of various interconnect structures with a diamond interconnect design.

The division of the secondary wiring creates an expansion zone to widen the layout of the wiring structure, while the formation of the secondary wiring creates a shrinkage space to narrow the layout of the wiring structure. Thus, from a layout standpoint, the contraction area of the wiring structure is at node X, whereas the expansion area of the wiring structure is at the point where the divided / gathering angle of the sub-wires varies between two adjacent nodes X.

As shown in FIG. 10, the node X of the first wiring structure and the node X of the second wiring structure are arranged at staggered positions. In this arrangement, the diamond-shaped vertex in the expansion zone of the first wiring structure lies next to the node X in the shrinking zone of the adjacent wiring structure. The staggered arrangement of these wiring structures can help lower the electrical noise due to the proximity of the wiring, thus reducing the distance between the wirings. The tight spacing between the interconnects can be made possible by placing the expansion zone of one interconnect structure closer to the contraction zone of the adjacent interconnect structure. For example, vertices in a wide part of one wiring structure can be placed in the open area FA1, the open area FA1 being made by the length of the sub-wiring in the adjacent wiring structure and the division / gather angle. This staggered arrangement allows a certain minimum distance between the wirings to be maintained while reducing the total space occupied by the wiring structures.

11A and 11B show schematic cross-sectional views of an exemplary wiring structure used in a flexible display device according to an embodiment of the present invention.

As mentioned, the cracks originate primarily from the inorganic insulating layer. Therefore, by selectively removing the inorganic insulating layer in the region in which cracking is likely to occur, propagation of cracks can be suppressed. To this end, a stack of insulating layers, including one or more inorganic insulating layers and / or inorganic layers, may be selectively etched at various portions of the flexible display device 100.

For example, the insulating layer under the lead 120 can be etched. The insulating layer under lead 120 may be a buffer layer 126, which may include one or more inorganic layers. Buffer layer 126 may be formed in one or more layers of silicon nitride (SiNx) layer and / or silicon oxide (SiO _2). As one configuration, the buffer layer 126 may be formed by laminating a SiNx layer and a SiO ₂ layer are alternately. A buffer layer 126 is disposed over the base layer 106 and below the TFT.

In order to facilitate easier bending of the flexible display device 100, a portion of the buffer layer 126 may be etched at the bent portions. Thus, the buffer layer 126 in the substantially flat portion may be thicker than the buffer layer 126 in the bent portion. When the buffer layer 126 is formed as a plurality of sub-layers, the substantially flat portion of the buffer layer 126 may include one or more additional sublayers as compared to the curved portion of the buffer layer.

For example, substantially as a buffer layer 126 on the flat side it may include a number of layers of SiNx, and SiO _2, the buffer layer 126 in the bending part may comprise a single layer of SiNx, and SiO _2. It is also possible to have one layer only of SiNx or SiO ₂ in a portion of the bending part. In one configuration, each layer in the buffer layer 126 may have a thickness of about 1000 angstroms. Thus, the thickness of the buffer layer 126 in the bent portion may range from about 100 A to about 2000 A.

In a substantially flat portion of the flexible display device 100, an additional inorganic layer may be provided directly below the semiconductor layer of the TFT, which may be referred to as an active buffer. In some embodiments, the inorganic layer closest to the semiconductor layer of the TFT may be thicker than the individual inorganic layer in the buffer layer 126. [

The buffer layer 126 within the flex section may be etched further to expose the base layer 106 while leaving the buffer layer 126 under the lead 120 intact. In other words, a recessed region and a protruded region are provided in the bent portion. The protruded region includes a buffer layer 126 provided on the base layer 106 while the recessed region has an exposed base layer 106 on which the buffer layer 126 is not disposed.

In the exemplary configuration shown in FIG. 11A, the lead 120 is located on the protruding region, and the protective layer 128 is located over the lead 120 on the protruding region. Although the protective layer 128 is not deposited on the depressed area, the protective layer 128 can be removed from the depressed area by dry or wet etching. Thus, the protective layer 128 can be substantially eliminated in the recessed region. When the protective layer 128 is etched from a depressed region, a portion of the base layer 106 may also be etched. Thus, the thickness of the base layer 106 in the recessed area may be less than the thickness of the base layer 106 elsewhere. When the buffer layer 126 is etched as shown in FIG. 11A, the propagation of the cracks from a part of the buffer layer 126 to another part is blocked by the space of the recessed area. Similarly, the crack propagation by the protective layer 128 is also blocked by the space of the recessed area. Thus, damage to the lead 120 due to crack propagation is reduced.

11B, the depressed region includes a base layer 106 etched to a certain depth, and the lead 120 is deposited on the base layer 106 in the depressed region. In this configuration, the portion of the lead 120 is disposed within the base layer 106. A portion of the lead 120 is also deposited on a portion of the buffer layer 126 provided in the protruded region. A protective layer 128 is deposited over the leads 120 and may be etched to expose the leads 120 in the depressed regions.

Thus, the protective layer 128 remains on the lead 120 located above the protruding region. In this configuration, the protective layer 128 remaining on the buffer layer 126 covers the end face of the side of the multi-layer conductive wire 120, thereby suppressing galvanic corrosion. The cracks generated in the buffer layer 126 can penetrate the lead 120 on the vacant space wall in the buffer layer 126 but it is difficult to reach the lead 120 located in the base layer 106. [

When the conductor 120 has the above-described multi-layer structure, a portion of the conductor 120 in the recessed area need not be covered with the protective layer 128. When the protective layer 128 is removed from the surface of the lead 120 in the recessed area, crack propagation from the protective layer 128 can be prevented. And if the conductors 120 on the buffer layer 126 and the conductors 120 on the base layer 106 are sufficiently spaced from each other, the galvanic corrosion typically begins at the edge of the lead 120 above the buffer layer 126, A protective layer 128 covering the edge of the lead 120 above the buffer layer 126 may not be needed. The configuration shown in Figs. 11A and 11B can be used together with the strain relief wiring patterns of Figs. 8, 9A and 9B for a bent section wiring structure. In addition to the bending section, in some embodiments the patterned insulating layer may also be provided in the routing region between the COF attachment region and the bending region and between the display region and the bending region.

Then, the patterned insulating layer described above may be provided in the display area. However, removing the inorganic insulating layer in the vicinity of the TFT may affect the electrical characteristics of the component. For example, removal of a portion of the buffer layer 126 may result in a threshold voltage shift of the undesired TFT. In order to maintain the stability of the TFT, an additional shield metal may be formed below the semiconductor layer of the TFT. The refractory metal layer may be under the buffer layer 126 or between the inorganic layers of the buffer layer 126. In some embodiments, the charge metal layer may be electrically connected to the source electrode or the gate electrode of the TFT.

In addition to the patterning of the insulating layer at various locations of the flexible display device 100, other structural elements may be removed or simplified in some areas of the flexible display device 100 for flexing. For example, the touch sensor layer 112, the polarizing layer 110, and the like may not exist in the bending section. Elimination or simplification of these elements will result in a large number of non-planar surfaces through which the wiring structure may pass.

When the wiring structure is on this nonplanar surface, one part of the wiring structure can be placed in a different plane than the other part. Since there are parts in different planes, the amount and direction of bending stress and its resulting deformation may vary within the interconnect structure. To accommodate this difference, the strain relief design of the interconnect structure may include a modified batch design for the interconnect structure on the non-planar surface.

12A is an enlarged cross-sectional view showing an exemplary backplane of the flexible display device 100. FIG.

The display device has a plurality of insulating layers removed at bent portions for reliable bending.

A plurality of organic and inorganic layers may be formed between the base layer 106 and the organic light emitting device layer 150. In this example, the SiNx and SiO ₂ layers may be alternately laminated on the base layer 106 to serve as the buffer layer 126. The semiconductor layer 151 of the TFT can be sandwiched between the active buffer layer 127 and the gate insulating layer 152 made of the SiO ₂ layer. The gate 152 of the TFT is disposed on the gate insulating layer 152 and the metal layer having the multilayer structure (the same metal as the source / drain of the TFT) is interposed between the interlayer insulating layer 154 and the protective layer 128. Here, the interlayer insulating layer 154 may be formed of a lamination of SiNx and SiO ₂ , and the passivation layer 128 may be formed of SiNx. Thereafter, a planarization layer is disposed over the protective layer 128, and the anode of the OLED is placed thereon.

As described above, the use of the deformation reduction design is not limited to a part of the wiring structure in the bent portion. In addition, the deformation reduction design can be applied to the wiring structure of the routing region outside the bending section. The use of deformation abatement design for the routing structure of this routing area can lead to improved protection against bending stress of the routing structure.

However, a plurality of organic and / or inorganic layers between the base layer 106 and the organic light emitting device layer 150 in the routing region may be removed to facilitate bending of the flexible display device 100. The organic and / or inorganic layer may be included in the interlayer insulating layer 154, the gate insulating layer 152, the buffer layers 126 and 127, the protective layer 128, the polarizing layer, It may not be in the flexion area. Some of these layers may be removed in certain areas by an etching process.

As an example, a plurality of insulating layers on the buffer layer 126 may be removed by a first etching process EB1. A first etching process (EB1) is followed by a part of an active buffer 127 and the buffer layer (126) followed by a second etching process (EB2) is removed (such as SiNx layer and an SiO ₂ layer of lamination). This etch process creates a number of step (step) regions as shown in FIG. 12A. The step region has one or more vertically inclined surfaces and a horizontally planar surface over which the leads are disposed. The vertically inclined surface and the conductive lines placed on the horizontally planar surface may have a plurality of bending points, such as areas between the high and low steps provided by the insulating layer.

When the flexible display device 100 is bent in the bending direction, the leads undergo a larger deformation in the stepped region and its vicinity. It has been pointed out in various studies and experiments that the possibility of cracking is particularly high in wiring across the step difference region between the EB1 and EB2 regions. Thus, in some embodiments, the strain relief design has a stiffening portion in and around the stepped region between the high and low ends made by the insulating layer.

In the example shown in Fig. 12B, the wiring structure has a simple linear wiring at both ends. However, a portion of the wire 120 across the flexing periods EB1 and EB2 is reinforced with a modified wiring design. In the modified portion, the lead 120 has a wider width with an additional width WR to ensure protection of the lead 120 against cracks originating from the insulating layer near the areas EB1 and EB2. The distance DR provided in the modified wiring design depends on the distance between the first elevation surface (eg, the height of the EB1 region) and the second elevation surface (eg, the height of the EB2 region) as well as the thickness of the insulating layer etched during the etching process do.

The deformation reduction design of the wiring structure to which the modified portion is applied is not limited to the design described in Fig. 12B. Various embodiments of the strain relief design can include a modified wiring design for a particular portion of the wiring that corresponds to a stepped region of different height.

Although not always, the routing region adjacent to the bending section may be a substantially flat portion of the flexible display device 100. [ In this case, the EB1 and EB2 regions may be located at the beginning or just outside the bending section in the bent portion, and the wiring structure may have the reinforcing portion.

The increased width WR of the portion of the reinforced conductor 120 meets this objective at the beginning and end of the curvature section with a relatively small curvature and in the vicinity thereof. The wider width WR of the wiring structure and the length to which the modified wiring portion is applied can increase the length of the wiring arranged in parallel to the bending direction. This will make the wiring structure harder to withstand bending stresses in the larger radius of bend radius.

For this reason, the distance DR with the reinforcing portion should be limited so that the reinforcing lead portion does not extend too far into the bending section. Therefore, the distance DR of the reinforcing wire portion can be limited so that the wiring of the reinforcing wire portion does not extend beyond the bending portion that is bent more than the predetermined critical bending angle. As an example, the reinforcing lead portion may not extend beyond the point of bending 30 degrees from the tangent plane. The critical bending angle may be less than 20 占 and may be 10 占 or 7 占 or less.

The wiring structure in which the reinforcing portion is provided in the stepped region can be extended across the bending section and connected to the pad or other parts of the COF. In this example, additional stepped regions (similar to EB1 and EB2) may be present at or near the opposite end of the bending section. The conductor at or near the bend point can be reinforced at the opposite end in a manner similar to the modified portion of the wiring structure, as in Fig. 12B. If desired, the lead wire reinforcement portion at or near the stepped region at the opposite end of the bending section may have a shape different from that described in Fig. 12B.

13 is a cross-sectional view of a flexible display device according to an embodiment of the present invention.

The flexible display device refers to a display device having flexibility, and includes a display device such as a bendable display device, a rollable display device, an unbreakable display device, a foldable display device, Can be used in the same sense as a foldable display device or the like. The flexible organic light emitting display device described below is an example of a flexible display device in which various structures and designs described in FIGS. 1 to 12 are reflected.

The flexible display device may include a display area and a non-display area as shown in FIG. In FIG. 13, the non-display area includes the bending section G while surrounding the display area, but the spirit of the present invention is not limited thereto. 13 is a cross-sectional view taken at specific points (A to G) of the organic light emitting device layer, the non-display region, and the bending section of the display region. Illustratively, A is a conceptual illustration of an area where there is a storage capacitor that stores a data signal (voltage). And B is a conceptual illustration of a region in which a thin film transistor (TFT) connected to the organic light emitting element is present. C is a conceptual illustration of a contact hole region in which the underlying protective metal 169 is connected to the gate material 153 and the source / drain material 155. And D is a conceptual illustration of a contact hole region to which the semiconductor layer 151 and the source / drain material 155 are connected. E is a conceptual illustration of a region where the gate material 153 and the source / drain material 155 are electrically connected. F is a conceptual illustration of a region in which gate lines supplying scan signals (or scan signals) are arranged. G is a conceptual illustration of a bending section.

Hereinafter, the layers shown in FIG. 13 will be described. The layers shown at points A through G are each structured layers through the same process. That is, the 'semiconductor layers' 151 at the points A to G are all formed in the X process, the 'gate material 153' is formed in the Y process, and the remaining layers are the same.

The base layer 106 supports various components of the flexible display device. When the base layer 106 is made of plastic, it may be referred to as a plastic film or a plastic substrate. For example, the base layer 106 may be in the form of a film including one selected from the group consisting of a polyester-based polymer, a silicone-based polymer, an acrylic-based polymer, a polyolefin-based polymer, and copolymers thereof. In detail, the base layer 106 may be formed of a material selected from the group consisting of polyethyleneterephthalate (PET), polybutylene terephthalate (PBT), polysilane, polysiloxane, polysilazene, polycarbosilane polycarbosilane, polyacrylate, polymethacrylate, polymethylacrylate, polymethylmethacrylate, polyethylacylate, polyethylmetacrylate, and the like. ), Cyclic olefin copolymer (COC), cyclic olefin polymer (COP), polyethylene (PE), polypropylene (PP), polyimide (PI), polystyrene (PS), polyacetal (PEEK), polyester sulfone (PES), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polycarbonate (PC), polyvinylidene fluoride (PFA), styrene acrylonitrile polymer (SAN), and combinations thereof. Of these materials, polyimide can be applied to a high-temperature process and is widely used as a plastic substrate because it is a material that can be coated. In a transparent flexible display device, the base layer 106 may be made of a transparent flexible material.

The buffer layers 126 and 127 are functional layers for protecting the thin film transistor from the base layer 106 or impurities such as alkali ions or the like flowing out from the lower layers. The buffer layer may include a multi buffer 126 and / or an active buffer 127.

A multi-buffer layer 126 is located on the base layer 106. The multi-buffer layer 126 may be formed by alternately stacking silicon nitride (SiNx) and silicon oxide (SiOx), and may delay diffusion of moisture and / or oxygen impregnated into the base layer 106. The multi-buffer layer 126 may be further disposed or removed depending on the material of the base layer 106 or the type of layer formed thereon. For example, as described above, in order to suppress the occurrence of cracks in the bending region, the multi-buffer layer may be disposed in the non-display region or the multi-buffer layer may be removed.

The active buffer layer 127 may be located on the multi-buffer layer 126. The active buffer 127 protects the semiconductor layer 151 of the transistor and functions to block various kinds of defects introduced from the base layer 106. The active buffer 126 may be formed of amorphous silicon (a-Si) or the like. The thin film transistor may be in the form of a semiconductor layer 151, a gate insulating layer 152, a gate 153, an interlayer insulating film 154, and a source and a drain 155 sequentially arranged. The thin film transistor may be a P-type TFT or an N-type TFT. The P-type TFT may be referred to as a PMOS, and the N-type TFT may be referred to as an NMOS.

The semiconductor layer 151 is located on the active buffer layer 127. At this time, the width of the semiconductor layer 151 may be smaller than the width of the lower protective metal 159, but is not limited thereto. The semiconductor layer 151 may be made of polycrystalline silicon, and in this case, a predetermined region may be doped with an impurity. In addition, the semiconductor layer 102 may be formed of amorphous silicon, an organic semiconductor material, or an oxide.

The gate insulating layer 152 may be located on the semiconductor layer 151. The gate insulator isolates the gate 153 and the semiconductor layer 151 from each other. The gate insulating layer 152 may be formed of an insulating inorganic material such as silicon oxide (SiOx) or silicon nitride (SiNx), or may be formed of an insulating organic material or the like.

The silicon oxide film (SiOx) and the silicon nitride film (SiNx) constituting the gate insulating layer 152 are less flexible than metal. Therefore, in order to improve the flexibility of the bending section, the bending section gate insulating layer can be removed.

The gate material 153 is located on the gate insulating layer 152. The gate material 153 may be any one of Mo, Al, Cr, Au, Ti, Ni, Ne and Cu, But is not limited thereto, and may be formed of various materials. In addition, the gate material 153 may be a single layer or multiple layers. In addition to being used as the gate electrode of the thin film transistor as at point B, the gate material 153 may also form a certain capacitance, such as at point A, or may be used as a connecting electrode, such as point C.

Interlayer dielectric layer 154) is located on the gate material 153. The interlayer insulating layer 154 may be formed of a silicon oxide film (SiOx), a silicon nitride film (SiNx) or a multilayer thereof, which is the same material as the gate insulating layer 152, but is not limited thereto. A contact hole through which the semiconductor layer 151 and / or the gate material 153 is exposed may be formed through selective removal of the interlayer insulating layer 154 and the gate insulating layer 152.

The source / drain material 155 is located on the interlayer dielectric layer 154. The source / drain material 155 may be any one of Mo, Al, Cr, Au, Ti, Ni, Ne, Or alloys thereof, but is not limited thereto, and may be formed of various materials. Also, the source / drain material 155 may be a single layer or multiple layers. In addition to being used as the source / drain electrode of the thin film transistor as at point B, the source / drain material 155 may also form a certain capacitance, such as at point A, or may be used as a connecting electrode, such as point C. The source / drain material 155 may also form a wire 120, such as at points F and G. [ The conductor 120 shown in Fig. 13 may be a part of the strain relief wiring structure described above.

The lower protective metal 169 may be located on the multi-buffer layer 126. Also, the bottom shield metal (BSM) may be located under the thin film transistor (for example, the lower protection metal may be located under the active buffer layer corresponding to the semiconductor layer of the thin film transistor) May be located below the semiconductor layer of all the transistors and may be located only below the semiconductor layer of a specific transistor (for example, a driving transistor) as needed. The lower protection metal 169 may be formed of a laser and a light It is possible to prevent variations in the device characteristics of the thin film transistor, for example, the threshold voltage or the on / off voltage, thereby preventing the unevenness in luminance between pixels. (E.g., threshold voltage) of the lower protection metal (BSM) is prevented from fluctuating. Thus, the bottom shield metal (BSM) The lower protective metal 169 can be prevented from being damaged during the manufacturing process of the flexible organic light emitting display device (for example, in the process of removing the glass substrate) Lt; RTI ID = 0.0 > physical < / RTI >

The lower protective metal 169 may be formed of the same material as the gate electrode 153 constituting the thin film transistor. On the other hand, since the lower protective metal 109 is made of a metal, it also becomes a device that forms a predetermined capacitance. At this time, if the lower protective metal 169 is electrically floating, there is variation in capacitance and the amount of shift of the threshold voltage of each of the thin film transistors may be varied, which may cause unintended visual defects (for example, Luminance change) can be generated. Therefore, the lower protective metal 169 may be grounded to the source / drain electrode or the gate electrode through the connecting member to maintain the capacitance constant.

When the lower protective metal 169 is connected to the source electrode or the drain electrode of the thin film transistor, an equipotential may be formed between the lower protective metal and the electrode connected to the lower protective metal. If the voltage difference between the electrodes connected to the lower protective metal and the lower protective metal is less than the voltage difference (i.e., VGS) between the gate electrode and the source electrode of the thin film transistor, then the lower protective metal 169 The effect on the voltage can be minimized.

When the lower protective metal 169 is connected to the gate electrode, the same voltage may be supplied to the gate electrode 153 and the lower protective metal 169. At this time, the lower protective metal 169 may act as an assist gate electrode of the thin film transistor. Additional channel regions may be provided on the surface of the active located on the underlying protective metal. Therefore, the mobility of the thin film transistor can be increased without substantially increasing the size of the thin film transistor. That is, the current driving capability of the thin film transistor can be improved.

The passivation layer 128 is located on the source / drain material 155. A protective layer 128 protects the source / drain material 155. A contact hole may be formed through selective removal of the protective layer 128 to expose the source / drain material 155. The protective layer 128 may be referred to as a second buffer layer, The first buffer layer 128 and the second buffer layer are referred to as the same components.

The planarization layer 156 is located on the protective layer. The planarization layer 156 protects the thin film transistor and flattenes the top of the thin film transistor. The planarization layer 156 may be formed of a material selected from the group consisting of polyacrylates resin, epoxy resin, phenolic resin, polyamide resin, polyimide resin, But is not limited to, one or more of unsaturated polyesters resin, poly-phenylenethers resin, polyphenylenesulfides resin, and benzocyclobutene. The planarization layer 156 may be formed of a single layer, or may be composed of multiple layers or multiple layers.

The organic light emitting device may have a structure in which a first electrode 112, an organic light emitting layer 158, and a second electrode 159 are sequentially arranged. That is, the organic light emitting device includes a first electrode 112 formed on the planarization layer 156, an organic light emitting layer 158 disposed on the first electrode 112, and a second electrode 159).

The first electrode 157 is electrically connected to the electrode 108 of the driving thin film transistor through the contact hole. The first electrode 157 may serve as an anode or a cathode depending on the type of the thin film transistor. When the organic light emitting display 100 is a bottom emission type, the first electrode 157 may be formed of a transparent conductive material (indium-tin-oxide (ITO) or indium-zinc- (IZO), etc.). When the OLED display 100 is a top emission type, the first electrode 157 may be made of an opaque conductive material having a high reflectivity. For example, the first electrode 157 may be formed of a metal such as silver (Ag), aluminum (Al), gold (Au), molybdenum (Mo), tungsten (W), chromium (Cr) ; Pb; Cu)) or the like.

The bank 160 is located on the planarization layer in the remaining region except for the light emitting region. At this time, the bank may form an opening region for exposing a portion of the first electrode 157. The bank 160 may be made of an inorganic insulating material such as a silicon nitride film (SiNx), a silicon oxide film (SiOx), or an organic insulating material such as BCB, acrylic resin or imide resin.

An organic light emitting layer 158 is positioned on the first electrode 112 exposed by the bank 160. The organic light emitting layer 158 may include a light emitting layer, an electron injection layer, an electron transport layer, a hole transport layer, a hole injection layer, and the like.

And the second electrode 159 is located on the organic light emitting layer 158. When the OLED display 100 is a top emission type, the second electrode 159 may be a transparent conductive layer such as indium tin oxide (ITO) or indium zinc oxide (IZO) Thereby emitting the light generated in the organic light emitting layer 158 to the upper portion of the second electrode 159.

The protective layer 161 and the encapsulation layer 162 are located on the second electrode 159. The passivation layer and the encapsulation layer prevent oxygen and moisture penetration from the outside in order to prevent oxidation of the light emitting material and the electrode material. When the organic light emitting device is exposed to moisture or oxygen, a pixel shrinkage phenomenon in which the light emitting region is reduced or a dark spot in the light emitting region may occur. The protective layer 161 and / or the sealing layer 162 may be made of an inorganic film made of glass, metal, aluminum oxide (AlOx), or silicon (Si) based material, or alternatively, Structure. The inorganic film serves to block penetration of moisture or oxygen, and the organic film serves to flatten the surface of the inorganic film. The reason why the encapsulation layer is formed of a plurality of thin film layers is to make the movement path of water or oxygen longer and more complicated than in the case of a single layer so as to make penetration of moisture / oxygen into the organic light emitting element difficult. Alternatively, the sealing layer 162 may be a barrier film.

A polarizing film, a touch panel (film), a top cover, and the like may be further disposed on the sealing layer 162.

FIGS. 14A to 14Q are diagrams illustrating a manufacturing step of a flexible display device according to an embodiment of the present invention.

14A shows the step of forming the base layer 106 and the multi-buffer layer 126. FIG.

The base layer 106 may be formed on the sacrificial layer after a sacrifice layer is formed on the auxiliary substrate (carrier substrate) first. The base layer 106 may be formed, for example, by a spin coating method. That is, after the liquid material containing the substance forming the base layer 106 is placed on the sacrificial layer, the auxiliary substrate may be rotated at a high speed to form the base layer 106 having a uniform thickness. The base layer 106 may be formed by a roll coating method or a slit coating method. In both of the above methods, the production efficiency can be high even if the thickness uniformity is low as compared with the spin coating method.

The multi-buffer layer 126 is deposited on the base layer 106. The multi-buffer layer 126 may be composed of a silicon oxide film (SiOx), a silicon nitride film (SiNx), or a multilayer thereof. At this time, a silicon oxide film (SiO x), a silicon nitride film (SiN x), etc. constituting the multi-buffer layer 126 can be deposited on the entire surface of the base layer 106. At this time, the multi-buffer layer 126 may be deposited through a chemical vapor deposition (CVD) process, a plasma enhanced chemical vapor deposition (PECVD) process, or the like, but is not limited thereto.

14B shows the step of forming the lower protective metal.

A lower protective metal 169 is formed on the multi-buffer layer 126. Where the underlying protective metal 169 is located at the bottom and / or other required portion of the thin film transistor. The lower protective metal 169 may be formed of the same material as the gate electrode constituting the thin film transistor. For example, the lower protective metal may be formed of a material such as molybdenum (Mo), but is not limited thereto. At this time, the lower protective metal 169 may be formed through a mask process (or photolithography process). That is, the lower protective metal 169 may be formed through a sputtering process using a mask in a region where the lower protective metal 169 is located. Alternatively, the lower protective metal 169 may be formed by depositing a metal on the entire surface of the multi-buffer layer 126, applying photoresist, exposing through a patterned mask, developing, etching, and removing a photosensitive resin.

14C shows a step of forming an active buffer layer.

The active buffer 127 may be formed on the multi-buffer layer 126 and / or the lower protective metal 169. At this time, the active buffer layer 127 may cover the lower protective metal 169. The active buffer 127 may be formed of amorphous silicon (a-Si) or the like and may be stacked on the upper surface of the base layer 106 and / or the lower protective metal 169.

14D shows a step of forming a semiconductor layer.

The semiconductor layer 151 may be formed on the active buffer 127. The semiconductor layer 151 formed at the thin film transistor region (point B) may be formed to be smaller than the width of the lower protective metal 169. In addition, the semiconductor layer 151 may be formed at points A and D. At this time, the semiconductor layer 151 may be formed through a mask process. For example, the semiconductor layer 151 may be located only in a designated region through a deposition process using a mask in the region to be patterned. Or the semiconductor layer 151 may be formed by depositing a semiconductor (Si, Ge or the like) on the entire surface of the active buffer 127 and then applying photoresist, exposure through a patterning mask, development, etching, .

14E shows a step of forming a gate insulating layer.

The gate insulating layer 152 may be formed on the semiconductor layer 151 and / or the active buffer layer 127. At this time, the gate insulating layer 152 may cover the semiconductor layer 151. The gate insulating layer 152 may be formed of an insulating inorganic material (a silicon oxide film (SiOx), a silicon nitride film (SiNx), or the like), an insulating organic material, or the like. The gate insulating layer 152 may be deposited on the entire surface of the semiconductor layer 151 and / or the active buffer layer 127.

After the gate insulating layer 152 is formed, a channel doping process may be performed to form a channel region in the semiconductor layer 151 of the thin film transistor. The channel doping may be formed through a mask process. For example, a mask may be disposed so as to correspond to a portion of the semiconductor layer 151 to be formed with a channel region, and then a doping process may be performed to implant impurities (ions) into a predetermined region through the opening region. At this time, the channel region of the semiconductor layer 151 may be doped with a Group 13 element such as boron or an NMOS or a Group 15 element such as phosphorus (PMOS), but is not limited thereto .

A step of forming a channel region in the semiconductor layer 151 of the thin film transistor and then forming a conductorized region (resistance region) in the remaining region (except for the channel region) of the semiconductor layer 151 ) Process) can be performed. The conducting region can also be formed in a semiconductor at another point. For example, when the semiconductor layer at the point B is doped, the semiconductor layer 151 at the point A, the semiconductor layer 151 at the point D, and the like may be doped together.

The conducting region may be formed through a mask process. For example, after the mask is disposed so as to correspond to all or a part of the semiconductor layer 151, a doping process may be performed. The conductorized region of the semiconductor layer 151 may be doped with a Group 15 element such as phosphorus or may be doped with a Group 13 element such as boron or the like (PMOS), but is not limited thereto. Also, the conducting region is doped with a high concentration of ions. The doping may be referred to as N ⁺ doping. Through this process, the portion of the semiconductor layer 151 at the point B to be in contact with the source / drain electrode, the semiconductor layer 151 at the point A and the semiconductor layer 151 at the point D which function as one electrode of the capacitor, .

14F shows the step of forming contact holes in the active buffer and gate insulating layer.

The contact holes may be formed through the active buffer 127 and the gate insulating layer 152 through a single mask process. At this time, a portion of the lower protective metal 169 is exposed through the contact hole. In this step, a photosensitive resin such as photoresist (PR) is applied on the gate insulating layer 152, and then a light can be selectively irradiated to the photosensitive resin in a specific region by using a mask. Subsequently, after developing the exposed photosensitive resin, the photosensitive resin of the light-irradiated portion can be removed. (When the photosensitive material is of the positive type), the gate insulating layer 152 is exposed at the portion where the photosensitive resin is removed. At this time, the exposed portion of the gate insulating layer 152 can be etched using the remaining photosensitive resin as a mask. Thereafter, when the photosensitive resin on the gate insulating layer 152 is removed by an ashing process, the contact holes of the gate insulating layer 152 and the active buffer layer 127 are completed.

Figure 14G shows the step of patterning the gate material.

A gate material 153 is formed on the gate insulating layer 152. At this time, the gate material 153 formed at the point B may overlap the semiconductor layer 151 in the vertical direction. The gate material 153 formed at the point C may be electrically connected to the lower protective metal 169 through the contact hole. The gate material 153 electrically connected to the lower protective metal 169 may be used as a lead. At this time, the process of forming the gate material 153 at a specific position may be performed in a similar manner to the process of forming the lower protective metal 169.

After the gate material 153 is formed, the semiconductor layer 151 may be doped with a specific impurity to form a lightly doped drain (LDD) region between the channel region of the semiconductor layer 151 and the conductorized region. At this time, the LDD region is formed between the channel region and the conductive region in the semiconductor layer, so that electrons can be easily moved between the two regions. At this time, the LDD region can be formed through a mask process. Specifically, after the mask is disposed (or the gate material becomes a mask) so as to correspond to the LDD region of the semiconductor layer 151, ions may be implanted into a predetermined region. At this time, the LDD region may be doped with a Group 15 element such as phosphorus (NMOS), but is not limited thereto. Also, when forming the LDD region, impurities (ions) are doped at a low concentration compared with the conducting region. For example, the LDD region can be doped at a concentration about 1000 times lower than the conducting region. The LDD doping may be referred to as N ^- doping. When the electrons move from the conducting region to the channel region, the OFF current is stabilized by the LDD region which is the buffer region, and the device reliability can be improved.

14H shows a step of forming an interlayer insulating layer.

An interlayer insulating layer 154 may be formed on the gate insulating layer 152 and / or on the gate material 153. At this time, the interlayer insulating layer 154 may cover the gate material 153. The interlayer insulating layer 154 may be formed of a silicon oxide film (SiOx), a silicon nitride film (SiNx), or a multilayer thereof, but is not limited thereto. An interlayer dielectric layer 154 may be deposited over the top surface of the base layer 106 and / or the gate material 153. As shown, the interlayer insulating layer 154 may be composed of two layers, but may be composed of more or less layers.

Fig. 14I shows a step of first etching the bending section G. Fig.

The interlayer insulating layer 154 and the gate insulating layer 152 formed in the bending section can be etched and removed through a mask process. The masking process at this time may include a step of applying a photosensitive resin, exposing through a patterning mask, developing, etching, and removing a photosensitive resin.

FIG. 14J shows a step of second-order etching the bending section G. FIG.

The active buffer 127 and at least a portion of the multi-buffer layer 126 formed in the bending section of the base layer 106 can be etched and removed through a mask process. In this case, the masking process may be performed in the order of exposure of the photosensitive resin, exposure through the patterning mask, development, etching, and removal of the photosensitive resin, similar to the first etching process. When the bending section G is secondarily etched, the multi-buffer layer 126 in the bending section may be thinner than the multi-buffer layer 126 in the display area. That is, the multi-buffer layer 126 of the bending section may have a smaller number of inorganic layers than the multi-buffer layer 126 of the display area.

14K shows a step of forming contact holes in the interlayer insulating layer and the gate insulating layer.

The contact holes may be formed through the interlayer insulating layer 154 and the gate insulating layer 152 through a single mask process. At this time, a part of the semiconductor layer 151 is exposed through the contact hole. Similar to the contact hole forming process shown in FIG. 14F, the process may be performed in the order of exposure of the photosensitive resin, exposure through the patterning mask, development, etching, and photoresist stripping.

Figure 14I illustrates the step of forming a source / drain material.

The source / drain material 155 is formed on the interlayer insulating layer 154. At this time, the source / drain material 155 may be electrically connected to the semiconductor layer 151 through a contact hole provided in the interlayer insulating layer 154. The source / drain material 155 may also be electrically connected to the gate material 153 through a contact hole provided in the interlayer insulating layer 154 at point C.

In the same process, the conductive line 120 may be formed on the multi-buffer layer 126 of the bending section G. [ For example, the lead 120 and the source / drain material 155 may be formed through a sputtering process that uses a mask in the region to be patterned. At this time, the lead 120 is formed of a material such as the source / drain material 155 (e.g., Cu, Mo / Ti, etc.).

FIG. 14M shows a step of thirdly etching the bending section G. FIG.

A passivation layer 128 may be formed on the source / drain material 155 prior to the third etching. A protective layer 128 may be formed on the top surface of the source / drain material 155. At this time, the passivation layer 128 may be formed to cover the source / drain material 155 of the display region and the lead 120 of the bending section G. FIG.

After the protective layer 128 is formed, a part of the protective layer formed in the bending section G may be etched and removed through a mask process. At this time, a portion of the base layer 106 may also be removed. In this case, the mask process may be performed in the same manner as the first and second etching processes, in the order of coating of the photosensitive resin, exposure through the patterning mask, development, etching, and photoresist removal.

14N shows a step of forming a contact hole in the protective layer.

The contact holes may be formed through the passivation layer 128 through a single mask process. A portion of the source / drain material 155 is then exposed through the contact hole. The process may be performed in the order of exposure of the photosensitive resin, exposure through the patterning mask, development, etching, and removal of the photosensitive resin, similarly to the process of FIG. 14F or 14K.

14O shows the step of forming a planarization layer.

The planarization layer 156 may be deposited over the top surface of the protective layer 128. At this time, they may not be stacked in the bending section G. The planarization layer 156 may then be provided with contact holes through a mask process. The contact hole of the planarization layer 156 may be formed to correspond to the contact hole of the protection layer 128. So that a portion of the source or drain electrode can be exposed through the contact holes. The planarization layer 156 may be formed as a single layer or a multi-layer.

14 (P) shows the step of forming the first electrode.

A first electrode (157) is formed on the planarization layer (156). At this time, the first electrode 157 may be electrically connected to the source electrode or the drain electrode through the contact hole provided in the planarization layer 156 and the protection layer 128. The first electrode 157 may be patterned through a mask process.

Figure 14q shows the step of forming the bank.

The bank 160 may be formed on the planarization layer 156. At this time, the bank 160 may be formed to have an opening region for exposing a portion of the first electrode 157. At this time, the bank 160 may be patterned through a mask process. An organic light emitting layer 158, a second electrode 159, a passivation layer 161 and an encapsulation layer 162 are sequentially formed after the banks 160 are formed.

15 is a cross-sectional view of a flexible display device according to another embodiment of the present invention.

The flexible display device 200 may include a display area and a non-display area as shown in FIG. Although FIG. 15 shows that the non-display area covers the outside of the display area and includes the bending section G ', the idea of the present invention is not limited thereto. FIG. 15 is a diagram showing a cross-sectional view extracted from a plurality of points (A to G ') on the display area and the non-display area.

A is a conceptual illustration of a storage capacitor region. The storage capacitor region means an area having a storage capacitor for storing a data voltage for driving the thin film transistor.

B is a conceptual illustration of the thin film transistor region. The thin film transistor region refers to a region where a thin film transistor is connected between a power source and an organic light emitting element to supply a current to the organic light emitting element.

C is a conceptual illustration of a lower protective metal contact hole (BSM-contact hole) region. The lower protection metal contact hole region means an area where the lower protection metal is electrically connected with the gate material used as a wiring to receive current.

And D is a conceptual illustration of a semiconductor layer contact hole (ACT-contact hole) region. The semiconductor layer contact hole region means a region where a semiconductor layer used as a wiring and a drive wiring are electrically connected.

F 'is a conceptual illustration of a pad area. The pad region means an area extending from the display area to a region where the driving wiring connected to the connection wiring of the bending area is disposed.

G 'is a conceptual illustration of a bending region (or bending region). The bending region is an area extending from the pad region, and means a region in which connection wirings connecting the pixel electrodes of the display region and the external module are disposed.

Hereinafter, the layers shown in FIG. 15 will be described. Each of the layers shown are structured layers through the same process.

The base layer (or flexible substrate) 206 supports various components of the flexible display device. When the base layer 206 is made of plastic, it may be referred to as a plastic film or a plastic substrate. For example, the base layer 206 may be in the form of a film containing one selected from the group consisting of a polyester-based polymer, a silicone-based polymer, an acrylic-based polymer, a polyolefin-based polymer, and a copolymer thereof. Specifically, the base layer 206 may be formed of at least one selected from the group consisting of polyethyleneterephthalate (PET), polybutylene terephthalate (PBT), polysilane, polysiloxane, polysilazene, polycarbosilane polycarbosilane, polyacrylate, polymethacrylate, polymethylacrylate, polymethylmethacrylate, polyethylacylate, polyethylmetacrylate, and the like. ), Cyclic olefin copolymer (COC), cyclic olefin polymer (COP), polyethylene (PE), polypropylene (PP), polyimide (PI), polystyrene (PS), polyacetal (PEEK), polyester sulfone (PES), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), polycarbonate (PC), polyvinylidene fluoride (PFA), styrene acrylonitrile polymer (SAN), and combinations thereof. Of these materials, polyimide can be applied to a high-temperature process and is widely used as a plastic substrate because it is a material that can be coated. In the transparent flexible display device, the base layer 106 may be made of a transparent flexible material.

The buffer layers 226 and 227 are functional layers for protecting the thin film transistor from impurities such as alkali ions or the like that flow out from the base layer 206 or the lower layers. The buffer layer may include a multi buffer 226 and / or an active buffer 227.

A multi-buffer layer (or first buffer layer) 226 is located on the base layer 206. At this time, the multi-buffer layer 226 may include a plurality of layers. The multi-buffer layer 226 may be formed by alternately stacking silicon nitride (SiNx) and silicon oxide (SiOx), and may delay the diffusion of moisture and / or oxygen impregnated into the base layer 206. The multi-buffer layer 226 may be further disposed or removed depending on the material of the base layer 206 or the type of layer formed thereon. For example, the multi-buffer layer 226 may be disposed less than the display area or the multi-buffer layer 226 may be removed in the non-display area in order to suppress the generation of cracks in the bending area, as described above. That is, the thickness of the multi-buffer layer 226 in the bending section G 'may be thinner than the thickness in other sections.

The active buffer (or first insulating layer) 227 may be located on the multi-buffer layer 226. In particular, the active buffer 227 may be disposed on the lower protective metal 269 (or the first protective member) at the pad section F '. The active buffer 227 protects the semiconductor layer 251 of the thin film transistor and functions to block various kinds of defects introduced from the base layer 206. The active buffer 226 may be formed of amorphous silicon (a-Si) or the like. The thin film transistor may have a semiconductor layer 251, a gate insulating layer 252, a gate material 253, an interlayer insulating layer 254, and a source and drain electrode 255 sequentially arranged.

The semiconductor layer 251 is located on the active buffer 227. At this time, the width of the semiconductor layer 251 may be smaller than the width of the lower protective metal 259, but is not limited thereto. The semiconductor layer 251 may be made of polycrystalline silicon, in which case a predetermined region may be doped with an impurity. In addition, the semiconductor layer 202 may be formed of amorphous silicon, an organic semiconductor material, or an oxide.

The gate insulating layer 252 may be located on the semiconductor layer 251. A gate insulator 252 insulates the gate material 253 from the semiconductor layer 251. The gate insulating layer 252 may be formed of an insulating inorganic material such as silicon oxide (SiOx) or silicon nitride (SiNx), or may be formed of an insulating organic material or the like.

Silicon oxide (SiOx) and silicon nitride (SiNx) constituting the gate insulating layer 252 are less flexible than metal. Therefore, in order to improve the flexibility of the bending section G ', the gate insulating layer 252 of the bending section G' can be removed.

The gate material 253 is located on the gate insulating layer 252. The gate material 253 may be formed of any one of Mo, Al, Cr, Au, Ni, Ni, But is not limited thereto, and may be formed of various materials. In addition, the gate material 253 may be a single layer or multiple layers.

The gate material 253 at point B may overlap the semiconductor layer 251 for driving the thin film transistor.

The gate material 253 at the point C may be electrically connected to the lower protective metal 269 located below the semiconductor layer 251 through the contact hole provided in the gate insulating layer 252 and the active buffer 227. [ At this time, the gate material 253 may be used as a wiring to electrically connect the lower protective metal 269 and the driving wiring 255. Therefore, the current supplied from the driving wiring 255 can be supplied to the lower protective metal 269 through the gate material 253 used as wiring. Also, the gate material 253 used as the wiring may be disposed on the active buffer 227, and may extend from the display region and be located in the pad section F '. The gate material 253 may be referred to as a gate wiring 253.

At this time, the gate wiring 253 extending from the display region can be electrically connected to the connection wiring 220 disposed in the pad section F '.

An interlayer insulating layer (or second insulating layer) 254 is located on the gate material 253. The interlayer insulating layer 254 is also located on the gate wiring 253 in the pad section F '.

The interlayer insulating layer 254 may be formed of silicon oxide (SiOx), silicon nitride (SiNx), or multiple layers thereof, which are the same material as the gate insulating layer 252, but are not limited thereto. A contact hole through which the source and drain regions are exposed may be formed through the selective removal of the interlayer insulating layer 254 and the gate insulating layer 252.

The driving wiring 255 is located on the interlayer insulating layer 254. At this time, the driving wiring 255 at the point B may overlap with the semiconductor layer 251 in a partial region. The driving wiring 255 may be electrically connected to the source and drain regions of the semiconductor layer 251 exposed through the contact holes provided in the interlayer insulating layer 254 and the gate insulating layer 252. [ At this time, the driving wiring 255 may be used as a source / drain electrode to supply current to the semiconductor layer 251.

The lower protective metal (or first protective member) 269 may be located on the multi-buffer layer 226. Also, a bottom shield metal ( BSM) 269 may be disposed under a thin film transistor (TFT). For example, the lower protective metal 269 may be located under the active buffer layer 227 corresponding to the semiconductor layer of the thin film transistor DD (TFT).

The lower protective metal 269 may be located below the semiconductor layer of all the transistors and may be located only below the semiconductor layer of a specific transistor (for example, a driving transistor) as required. At this time, the lower protective metal 269 prevents variations in device characteristics, such as threshold voltage or on / off voltage, of the thin film transistor from the laser and the light introduced from the outside, thereby preventing the luminance unevenness between pixels. In addition, the lower protective metal 269 suppresses variation in element characteristics (e.g., threshold voltage, etc.) of the transistor from moisture that flows from the outside. Thus, the bottom shield metal (BSM) 269 can prevent the unevenness of the brightness between the pixels (unevenness and residual image). Furthermore, the lower protective metal 269 may minimize the physical damage of the transistor in the manufacturing process of the flexible display device 200 (e.g., the process of removing the glass substrate). That is, the lower protective film 269 is disposed under the thin film transistor (TFT) to protect the thin film transistor (TFT). At this time, the lower protective metal 269 may be referred to as a thin film transistor (TFT) protective member.

The lower protective metal 269 may be formed of the same material as the gate material 253 constituting the thin film transistor. On the other hand, since the lower protective metal 209 is made of a metal, it also becomes a device that forms a predetermined capacitance. At this time, if the lower protective metal 269 is electrically floating, there is variation in capacitance and the amount of shift of the threshold voltage of each of the thin film transistors may be varied, which may cause unintended visual defects (for example, Luminance change) can be generated. Thus, the lower shielding metal 269 can be grounded to the source / drain electrode or gate material through the connecting member to keep the capacitance constant.

When the lower protective metal 269 is connected to the source electrode or the drain electrode of the thin film transistor, an equipotential may be formed between the lower protective metal 269 and the electrode connected to the lower protective metal 269. If the voltage difference between the electrodes connected to the lower protective metal 269 and the lower protective metal 269 is less than the voltage difference (i.e., VGS) between the gate material and the source electrode of the thin film transistor, ) On the threshold voltage of the thin film transistor can be minimized.

When the lower protective metal 269 is connected to the gate material 253, the same voltage may be applied to the gate material 253 and the lower protective metal 269. At this time, the lower protective metal 269 may operate as an assist gate material of the thin film transistor. Additional channel regions may be provided on the surface of the semiconductor layer that is located on the underlying protective metal 269. [ Therefore, the mobility of the thin film transistor can be increased without substantially increasing the size of the thin film transistor. That is, the current driving capability of the thin film transistor can be improved.

The lower protective metal 269 may also be disposed on the multi-buffer layer 226 in the pad section F '. The lower protective metal 269 is then spaced apart from another adjacent lower protective metal 269 to prevent a short (or electrical connection) between the connecting wirings 220 disposed on the lower protective metal 269 .

The lower protection metal 269 disposed in the pad section F 'may be the same material as the lower protection metal 269 (or the thin film transistor protection member) disposed in the display region of the flexible display device 200. [ At this time, the pad section F 'and the lower protective metal 269 formed in the display area are formed together, so that the manufacturing process of the flexible display device 200 can be simplified.

The lower protective metal 269 disposed in the pad section F 'is used to etch the bending section G' of the flexible display device 200 in order to manufacture the flexible display device 200, 269 may be protected. At this time, a part of the multi-buffer layer 226 and the active buffer layer 227 on the multi-buffer layer 226 can be removed by the same patterning equipment. Therefore, the manufacturing process of the flexible display device 200 can be simplified.

The connection wiring 220 is disposed in the non-display area of the base layer 206. The connection wiring 220 may be disposed on the multi-buffer layer 226 disposed in the pad section F 'and the bending section G' of the non-display area of the base layer 206. Specifically, a part of the connection wiring 220 is disposed on the interlayer insulating layer 254 disposed in the pad section F 'of the base layer 206. At this time, the connection wiring 220 may be electrically connected to the gate wiring 253 disposed in the pad section F '. A portion other than a portion of the connection wiring 220 may be disposed on the multi-buffer layer 226 disposed in the bent section G 'of the base layer 206. [ The connection wiring 220 can be bent when the bending section G 'of the base layer 206 is bent. The connection electrode 220 may electrically connect an external module disposed in a non-display area, for example, a flexible printed circuit board (FPCB), or a chip on film (COF), to the pixel electrode of the display area of the display device.

The protective layer 228 (or the second buffer layer) is located on the driving wiring 255. The protective layer 228 functions to protect the thin film transistor. Further, the protective layer 228 may cover and protect the connection wiring 220 disposed in the bending section G '.

The planarization layer 256 is located on the protective layer 228. The planarization layer 256 protects the thin film transistor and flattenes the top of the thin film transistor. The planarization layer 256 and the protective layer 228 may have contact holes through which the source or drain electrode is exposed through selective removal. The source or drain electrode may be electrically connected to the first electrode 257 through the exposed contact hole.

The planarization layer 256 may be formed of a material selected from the group consisting of polyacrylates resin, epoxy resin, phenolic resin, polyamide resin, polyimide resin, But is not limited to, one or more of unsaturated polyesters resin, poly-phenylenethers resin, polyphenylenesulfides resin, and benzocyclobutene. The planarization layer 256 may be formed as a single layer, or may be composed of multiple layers or multiple layers.

The organic light emitting device may have a structure in which a first electrode 257, an organic light emitting layer 258, and a second electrode 259 are sequentially disposed. That is, the organic light emitting device includes a first electrode 257 formed on the planarization layer 256, an organic light emitting layer 258 disposed on the first electrode 257, and a second electrode 258 disposed on the organic light emitting layer 258. [ 259).

The first electrode 257 is electrically connected to the electrode 208 of the driving thin film transistor through the contact hole. The first electrode 257 may serve as an anode or a cathode depending on the type of the thin film transistor. When the flexible display device 200 is a bottom emission type, the first electrode 257 is formed of a transparent conductive material (indium-tin-oxide (ITO) or indium-zinc-oxide IZO), etc.). When the flexible display device 200 is a top emission type, the first electrode 257 may be made of an opaque conductive material having a high reflectivity. For example, the first electrode 257 may be formed of a metal such as silver (Ag), aluminum (Al), gold (Au), molybdenum (Mo), tungsten (W), chromium (Cr) ; Pb; Cu)) or the like.

The bank 260 is located on the planarization layer 256 in the remaining region except for the light emitting region. At this time, the bank 260 may form an opening region that exposes a portion of the first electrode 257. The bank 260 may be made of an inorganic insulating material such as silicon nitride (SiNx), silicon oxide (SiOx), or an organic insulating material such as BCB, acrylic resin or imide resin.

An organic light emitting layer 258 is positioned on the first electrode 257 exposed by the bank 260. The organic light emitting layer 258 may include a light emitting layer, an electron injection layer, an electron transport layer, a hole transport layer, a hole injection layer, and the like.

And the second electrode 259 is located on the organic light emitting layer 258. When the flexible display device 200 is a top emission type, the second electrode 259 may be formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO) Thereby emitting the light generated in the organic light emitting layer 258 to the upper portion of the second electrode 259.

A protective film 261 and an encapsulating layer 262 are disposed on the second electrode 259. The passivation layer 261 and the encapsulation layer 262 prevent oxygen and moisture penetration from the outside in order to prevent oxidation of the light emitting material and the electrode material. When the organic light emitting device is exposed to moisture or oxygen, a pixel shrinkage phenomenon in which the light emitting region is reduced or a dark spot in the light emitting region may occur. The protective layer 261 and / or the sealing layer 262 may be made of an inorganic layer made of glass, metal, aluminum oxide (AlOx) or silicon (Si) based material, or alternatively a structure in which an organic layer and an inorganic layer are alternately stacked Lt; / RTI > The inorganic film serves to block penetration of moisture or oxygen, and the organic film serves to flatten the surface of the inorganic film. The reason why the encapsulation layer is formed of a plurality of thin film layers is to make the movement path of water or oxygen longer and more complicated than in the case of a single layer so as to make penetration of moisture / oxygen into the organic light emitting element difficult. Alternatively, the sealing layer 262 may be a barrier film.

A polarizing film, a touch panel (film), a top cover, and the like may be further disposed on the sealing layer 262.

16 is a cross-sectional view of a flexible display device according to another embodiment of the present invention.

The flexible display device 300 shown in Fig. 16 further includes the upper protective metal 367 as compared with the flexible display device 200 shown in Fig. 15, and the structure related thereto is changed only, , So redundant explanations are omitted.

The upper protective metal (or the second protective member) 367 may be disposed on the gate insulating layer 351 in the pad section F '. At this time, the upper protective metal 367 may be formed together with the gate wiring 353. Therefore, the upper protective metal 367 may be formed of the same material as the gate wiring 353. At this time, the upper protective metal 367 may be disposed between the active buffer 327 and the interlayer insulating layer 354.

The upper protective metal 367 may be exposed during the manufacturing process of the flexible display device to expose the base layer 306 between the lower protective metal 369 and another adjacent lower protective metal 369 to prevent the presence of foreign matter . Therefore, a short (or electrical connection) between the connection wirings 320 can be prevented.

The upper protection metal 367 may be formed by a process of etching the bending section G 'of the flexible display device 300 to fabricate the flexible display device 300, The layer 351 and the active buffer 327 can be protected. At this time, a part of the gate insulating layer 351 and a part of the active buffer 327 can be removed by the same patterning equipment. Therefore, the manufacturing process of the flexible display device 300 can be simplified. At this time, the end of the upper protective metal 367 may be provided to be located inside the end of the interlayer insulating layer 354 located on the upper protective metal 367.

17A to 17R are views showing a manufacturing procedure of a flexible display device according to another embodiment of the present invention.

17A to 17R are views for explaining a manufacturing method of the flexible display device 200 according to an embodiment of the present invention shown in FIG. In particular, a cross-sectional view of each step of the method for manufacturing the flexible display device 200 according to the present invention is shown.

Figure 17A illustrates the step of forming the base layer 206 and the multi-buffer layer 226. [

The base layer 206 may be formed on the sacrificial layer after a sacrifice layer is formed on the auxiliary substrate (carrier substrate) first.

For example, the base layer 206 may be formed by a spin coating method. That is, after the liquid material containing the substance forming the base layer 206 is placed on the sacrificial layer, the auxiliary substrate may be rotated at a high speed to form a thin base layer 206 having a uniform thickness.

The base layer 206 may be formed by a roll coating method or a slit coating method. In both of the above methods, the production efficiency can be high even if the thickness uniformity is low as compared with the spin coating method.

The multi-buffer layer 226 is deposited on the base layer 206. At this time, the multi-buffer layer 226 may be formed of a plurality of layers. The multi-buffer layer 226 may be formed of silicon oxide (SiOx), silicon nitride (SiNx), or multiple layers thereof. At this time, silicon oxide (SiO x), silicon nitride (SiN x), or the like constituting the multi-buffer layer 226 may be deposited on the entire surface of the base layer 206. At this time, the multi-buffer layer 226 may be deposited through a chemical vapor deposition (CVD) process, a plasma enhanced chemical vapor deposition (PECVD) process, or the like, but is not limited thereto.

Figure 17B shows the step of forming a lower protective metal.

A lower protective metal 269 is formed on the multi-buffer layer 226. Where the underlying protective metal 269 is located at the bottom and / or other required portion of the thin film transistor. At this time, the lower protective metal 269 should be formed in consideration of the semiconductor layer of the thin film transistor (TFT). The lower protective metal 269 may also be formed on the multi-buffer layer 226 at the pad section F 'and the bending section G'. The lower protective metal 269 is then bonded to another adjacent lower protective metal 269 and the pad section F 'to prevent a short (or electrical connection) between the connecting electrodes disposed on the lower protective metal 269, ) And the bending section (G '). At this time, the lower protective metal 269 may be patterned. The lower protective metal 269 may be formed of the same material as the gate material constituting the thin film transistor. For example, the lower protective metal 269 may be formed of a material such as molybdenum (Mo), but is not limited thereto. At this time, the lower protective metal 269 may be formed through a mask process (or a photolithography process). That is, the lower protective metal 269 may be formed through a sputtering process using a mask in a region where the lower protective metal 269 is to be patterned. Alternatively, the lower protective metal 269 may be formed by depositing the metal on the entire surface of the multi-buffer layer 226, applying photoresist, exposing through a patterned mask, developing, etching, and removing the photosensitive resin have.

Figure 17C shows the step of forming an active buffer.

The active buffer 227 may be formed on the multi-buffer layer 226 and / or the lower protective metal 269. At this time, the active buffer 227 may cover the lower protective metal 269. In particular, the active buffer 227 may be formed to cover the lower protective metal 269 at the pad section F 'and the bending section G'.

The active buffer 227 may be formed of amorphous silicon (a-Si) or the like and may be deposited on the upper surface of the base layer 206 and the lower protective metal 269.

17D shows a step of forming a semiconductor layer.

The semiconductor layer 251 may be formed on the active buffer 227. The semiconductor layer 251 formed at point B may be formed to be smaller than the width of the lower protective metal 269 so as to correspond to the lower protective metal 269. Further, the semiconductor layer 251 may be formed at points A and D. At this time, the semiconductor layer 251 may be formed through a mask process. For example, the semiconductor layer 251 may be formed only in a region designated through a deposition process using a mask in an area to be patterned. (Si, Ge, or the like) may be deposited on the entire surface of the active buffer 227, followed by applying a photoresist, exposing through a patterning mask, developing, etching, and removing a photosensitive resin.

17E shows a step of forming a gate insulating layer.

The gate insulating layer 252 may be formed on the semiconductor layer 151 and / or the active buffer 227. At this time, the gate insulating layer 252 may cover the semiconductor layer 251.

The gate insulating layer 252 may be formed of an insulating inorganic material such as silicon oxide (SiOx), silicon nitride (SiNx), or the like, or an insulating organic material. A gate insulating layer 252 may be deposited over the semiconductor layer 151 and / or over the active buffer 127. After the gate insulating layer 252 is formed, a channel doping process may be performed to form a chanel area in the semiconductor layer 251 of the thin film transistor. The channel doping may be formed through a mask process. The doping process can be performed after arranging the mask so as to correspond to the portion of the semiconductor layer 251 in which the channel region of the thin film transistor is to be formed. At this time, the channel region of the semiconductor layer 251 may be doped with a Group 13 element such as boron or an NMOS or a Group 15 element such as phosphorus (PMOS), but is not limited thereto .

A process of forming a conductive region (resistance region) in the remaining region of the semiconductor layer 251 (e.g., a storage doping process) is performed after forming a channel region in the semiconductor layer 251 of the thin film transistor . The conducting region may also be formed in the semiconductor at another point. For example, the semiconductor layer 151 at the point A, the semiconductor layer 251 at the point D, and the like may be doped together.

The conducting region may be formed through a mask process. For example, a doping process may be performed after arranging the mask so as to correspond to all or a part of the semiconductor layer 151. [ The conducting region of the semiconductor layer 251 may be doped with a Group 15 element such as phosphorus or may be doped with a Group 13 element such as boron or the like (PMOS), but is not limited thereto. Also, the doped region is sometimes referred to as N + doping, because the doped region is highly doped with ions. Through this process, the portion of the semiconductor layer 251 at the point B to be in contact with the source / drain electrode, the semiconductor layer 251 at the point A and the semiconductor layer 251 at the point D to function as one electrode of the capacitor, .

17F shows the step of forming contact holes in the active buffer and gate insulating layer.

The contact holes may be formed together through the active buffer 227 and the gate insulating layer 252 through a single mask process. At this time, a portion of the lower protective metal 269 is exposed through the contact hole. For example, after a photosensitive resin such as photoresist (PR) is applied on the gate insulating layer 252, a light can be selectively irradiated only to a photosensitive resin in a specific region by using a mask. Subsequently, after developing the exposed photosensitive resin, the photosensitive resin portion irradiated with the light can be removed. (When the photosensitive material is a positive type), the gate insulating layer 252 is exposed at the portion where the photosensitive resin is removed. At this time, the exposed portion of the gate insulating layer 252 can be etched using the remaining photosensitive resin as a mask. After the gate insulating layer 252, if the photosensitive resin on the gate insulating layer 252 is removed by an ashing process, the contact hole of the gate insulating layer 252 is completed.

Figure 17g shows the step of forming a gate material.

A gate material 253 is formed on the gate insulating layer 252. At this time, the gate material 253 formed at the point B may overlap the semiconductor layer 251 in the vertical direction. The gate material 253 formed at the point C may be electrically connected to the lower protective metal 269 through the contact hole. The gate material 253 electrically connected to the lower protective metal 269 may be used as a wiring. Also, a gate material 253 used as a wiring may be formed on the active buffer 227, and may extend from the display area and be located in the pad section F '. The gate material 253 may be referred to as a gate wiring 253. At this time, the process of forming the gate material 253 may be performed similarly to the process of forming the lower protective metal 269.

After the gate material 253 is formed, the semiconductor layer 251 may be doped with a specific impurity to form a lightly doped drain (LDD) region between the channel region of the semiconductor layer 251 of the thin film transistor and the conducting region have. At this time, the LDD region is formed between the channel region and the conductive region in the semiconductor layer, so that electrons can be easily moved between the two regions. At this time, the LDD region can be formed through mask fixing. Specifically, after the mask is disposed so as to correspond to the LDD region of the semiconductor layer, the doping process can be performed. At this time, the LDD region may be doped with a Group 15 element such as phosphorus (NMOS), but is not limited thereto. Also, when forming an LDD region, impurities (ions) must be doped at a low concentration compared with the conducting region. For example, the LDD region can be doped at a concentration about 1000 times lower than the conducting region. Therefore, LDD doping can be called N-doping.

17H shows a step of forming an interlayer insulating layer.

An interlayer insulating layer 254 may be formed on the gate insulating layer 252 and / or on the gate material 253. At this time, the interlayer insulating layer may cover (254) the gate material 253. Further, the interlayer insulating layer 254 may be formed so as to cover the gate wiring 253 in the pad section F '.

The interlayer insulating layer 254 may be formed of silicon oxide (SiOx), silicon nitride (SiNx), or multiple layers thereof, but is not limited thereto. At this time, the interlayer insulating layer 254 may be formed in the display area and the non-display area of the flexible display device. That is, the interlayer insulating layer 254 may be deposited on the upper surface of the base layer 206 and / or the gate material 253.

FIG. 17I shows a step of first etching the bending section G '.

An interlayer insulating layer 254 formed in the bending section G 'of the base layer 206 among the interlayer insulating layer 254, the gate insulating layer 252 and the multi-buffer layer 226 formed on the entire surface of the base layer 206, The gate insulating layer 252 and the multi-buffer layer 226 may be partially etched and removed. At this time, the multi-buffer layer 226 under the lower protective metal 269 formed in the bending section G 'may not be etched. That is, the interlayer insulating layer 254 and the gate insulating layer 252 on the lower protective metal 269 formed in the bending section G 'can be etched and removed. At this time, the lower protective metal 269 formed in the bending section G 'may be exposed.

A part of the interlayer insulating layer 254, the gate insulating layer 252 and the multi-buffer layer 226 in the region where the lower protective metal 269 is not disposed in the bending section G 'can be etched and removed . At this time, the multi-buffer layer 226 may be etched to remove some of the plurality of layers. At this time, the interlayer insulating layer 254, the gate insulating layer 252, and the multi-buffer layer 226 may be etched and removed through a mask process. The masking process may include a PR coating similar to the mask process for forming contact holes in the active buffer 227 and the gate insulating layer 252, exposure through a patterning mask, development, etch, and PR removal. The flexibility of the bending section G 'of the flexible display device 200 can be improved when the interlayer insulating layer 254 and the gate insulating layer 252 are removed in the bending section G'.

FIG. 17J shows the step of etching the lower protective metal exposed in the bending section G '.

At this time, the lower protective metal 269 exposed in the bending section G 'may be removed through wet-etching. Accordingly, the multi-buffer layer 226 can be exposed in the bending section G '.

17K shows a step of second-order etching the bending section G '.

A portion of the multi-buffer layer 226 exposed in the bending section G 'may be etched away. At this time, the multi-buffer layer 226 in the region where the lower protective metal 269 is not formed in the bending section G 'may be etched and removed. Also, the multi-buffer layer 226 in the region where the lower protective metal 269 was formed in the bending section G 'can be partially etched. At this time, the multi-buffer layer 226 may be etched and removed through a mask process. In this case, the mask process may be performed in the order of exposure, development, etching, and PR removal through the PR coating, the patterning mask, and the like, similar to the first etching process. The mask process for secondarily etching the bending section G 'may be performed using the same masking device as the mask process for firstly etching the bending section G'.

When the bending section G 'is secondarily etched, the multi-buffer layer 226 of the bending section G' may be thinner than the multi-buffer layer 226 of the display area. That is, the multi-buffer layer 126 of the bending section G 'may have a smaller number of inorganic layers than the multi-buffer layer 226 of the display area. Therefore, the flexibility of the bending section G 'of the flexible display device 200 can be improved.

The bending section G 'of the flexible display device 200 can be formed thinner than other regions by the first etching and the second etching.

The lower protective metal 269 disposed at the bending section G 'may serve as a barrier between the upper layers of the lower protective metal 269 and the lower buffer layer 269 . Accordingly, when a first section of the bending section G 'is etched, the layers formed on the lower protective metal layer 269 can be removed by etching. Thereafter, the multi-buffer layer 226 formed under the lower protective metal 269 may be etched by etching the bending section G 'after the lower protective metal 269 is removed.

At this time, the lower protective metal 269 may serve as an etch stopper. Therefore, uniformity between the curved sections G 'can be improved by using the same mask when the curved section G' is subjected to the first etching and the second etching. Therefore, the manufacturing process of the flexible display device 200 can be simplified.

Also, the uniformity between the bending sections G 'is improved and the flexibility of the bending sections G' can be improved. Accordingly, when the connection wiring 220 formed in the bending section G 'is bent, the connection wiring 220 can be prevented from being damaged.

Figure 17L shows the step of forming a contact hole in the interlayer insulating layer or the gate insulating layer.

The contact hole may be formed through the interlayer insulating layer 254 and the gate insulating layer 252 through a single mask process. At this time, a part of the semiconductor layer 251 is exposed through the contact hole. Similar to the contact hole forming process of FIG. 16F, the process may be performed in the order of exposure, development, etching, and PR removal through the PR coating, the patterning mask, and the like.

Fig. 17M shows a step of forming a drive wiring and a connection wiring.

The driving wiring 255 is formed on the interlayer insulating layer 254. [ At this time, the driving wiring 255 may be formed to be electrically connected to the semiconductor layer 251 through the contact hole provided in the interlayer insulating layer 254. The driving wiring 255 may be formed to be electrically connected to the gate material 253 through the contact hole provided in the interlayer insulating layer 254 at the point C.

The connection wiring 220 may be formed on the multi-buffer layer 226 at the pad section F 'and the bending section G'. Specifically, a part of the connection wiring 220 is formed on the interlayer insulating layer 254 formed in the pad section F 'of the base layer 206. At this time, the connection wiring 220 may be electrically connected to the gate wiring 253 disposed in the pad section F '. A portion other than a part of the connection wiring 220 may be formed on the multi-buffer layer 226 formed in the bending section G 'of the base layer 206. [ At this time, the driving wiring 255 and the connection wiring 220 may be formed together through a mask process. The driving wiring 255 and the connection wiring 220 may be formed through a sputtering process using, for example, a mask in a region to be patterned. Further, the driving wiring 255 and the connection wiring 220 may be formed together, so that they may be formed of the same material. In this case, a low resistance conductive material such as Cu may be used as the material, and may be formed into a multi-layer structure using MoTi or the like depending on the case, but the present invention is not limited thereto.

FIG. 17N shows a step of thirdly etching the bending section G '.

A protective layer 228 is formed on the base layer 206 before the third etching. The protective layer 228 may be formed on the front surface of the base layer 206. The protective layer 228 may be formed to cover the driving wiring 255 of the display area and the connection wiring 220 of the pad section F 'and the bent section G'. After the protective layer 228 is formed, a part of the protective layer 228 formed in the bending section G 'may be etched and removed through a mask process. At this time, a portion of the base layer 206 may also be removed. Therefore, the flexibility of the bending section G 'of the flexible display device 200 can be improved. In this case, the mask process may be performed in the order of PR coating, exposure through the patterning mask, development, etch, and PR removal processes, similar to the first and second etching processes

Figure 17O shows the step of forming a contact hole in the protective layer.

The contact hole may be formed through a passivation layer 228 through a single mask process. At this time, a portion of the source / drain electrode 255 is exposed through the contact hole. The process may be performed in the order of the PR coating, the exposure through the patterning mask, the development, the etching, and the PR removal process, similarly to the process of FIG. 17F or FIG. 17L.

Figure 17P shows the step of forming a planarization layer.

The planarization layer 256 may be deposited over the entire top surface of the protective layer 228. At this time, they may not be stacked in the bending section G '. The planarization layer 156 may then be provided with contact holes through a mask process.

The contact holes provided in the planarization layer 256 may be formed to correspond to the contact holes provided in the protection layer 228. So that a portion of the source or drain electrode can be exposed through the contact holes. The planarization layer 256 may be formed as a single layer or a multilayer.

Figure 17q shows the step of forming the first electrode.

A first electrode 257 is formed on the planarization layer 256. At this time, the first electrode 257 may be electrically connected to the source electrode or the drain electrode through the contact hole provided in the planarization layer 256 and the protective layer 228.

The first electrode 257 may be patterned through a mask process.

Figure 17r shows the step of forming banks.

The bank 260 may be formed on the planarization layer 256. At this time, the bank 260 may be formed to have an opening region that exposes a portion of the first electrode 257.

At this time, the bank 260 may be patterned through a mask process.

An organic light emitting layer 258, a second electrode 259, a protective layer 261 and an encapsulation layer 262 are sequentially formed after the banks 260 are formed.

18A to 18R are views showing a manufacturing procedure of a flexible display device according to another embodiment of the present invention.

18A to 18R are views for explaining a manufacturing method of the flexible display device 300 according to another embodiment of the present disclosure shown in FIG. Sectional views of the flexible display device 300 according to the respective steps of the method for manufacturing the flexible display device 300 according to the present invention.

The manufacturing method of the flexible display device 300 shown in Figs. 18A to 18R further includes the upper protective metal 367 in comparison with Figs. 17A to 17R, and only the manufacturing method related thereto is changed, They are substantially the same, so redundant explanations are omitted. Therefore, Figs. 18A to 18R will be described with reference to Figs. 18G to 18K in which the manufacturing method is changed as compared with Figs. 17A to 17R.

Figure 18g shows the step of forming a gate material.

A gate material 353 is formed on the gate insulating layer 352. At this time, the gate material 353 formed at the point B may overlap the semiconductor layer 351. The gate material 353 formed at point C is formed to be electrically connected to the lower protective metal 369 located under the semiconductor layer 351 through the contact hole provided in the gate insulating layer 352 and the active buffer 327 . The gate material 353 electrically connected to the lower protective metal 369 may be used as a wiring. Also, the gate material 353 used as the wiring may be formed on the active buffer 327, and may extend from the display area and be located in the pad section F '. At this time, the gate material 353 may be referred to as a gate wiring 353.

The gate material 353 may also be located above the bottom protective metal 369 at the pad section F 'and the bending section G'. The gate material 353 may be referred to as the upper protective metal 367. The upper protective metal 367 may be formed to cover a portion of the gate insulating layer 351 at the pad section F 'and the bending section G'. Thus, the top protective metal 351 may be formed of the same material as the gate material 353. At this time, the process may be performed similarly to the process of forming the gate material 353.

After the gate material 353 is formed, the semiconductor layer 351 may be doped with a specific impurity to form a lightly doped drain (LDD) region between the channel region and the conducting region of the semiconductor layer 351 of the baking transistor. have. At this time, the LDD region is formed between the channel region and the conductive region in the semiconductor layer, so that electrons can be easily moved between the two regions. At this time, the LDD region can be formed through mask fixing. Specifically, after the mask is disposed so as to correspond to the LDD region of the semiconductor layer, the doping process can be performed. At this time, the LDD region may be doped with a Group 15 element such as phosphorus (NMOS), but is not limited thereto. Also, when forming an LDD region, impurities (ions) must be doped at a low concentration compared with the conducting region. For example, the LDD region can be doped at a concentration about 1000 times lower than the conducting region. Therefore, LDD doping can be called N-doping.

18H shows a step of forming an interlayer insulating layer.

An interlayer insulating layer 354 is formed on the gate insulating layer 352. At this time, the interlayer insulating layer may cover the gate material 353 (354). The interlayer insulating layer 354 may be formed so as to cover the gate wiring 353 in the pad section F '. The interlayer insulating layer 354 may be formed to cover the upper protective metal 367 in the pad section F 'and the bending section G'.

The interlayer insulating layer 354 may be formed of silicon oxide (SiOx), silicon nitride (SiNx), or multiple layers thereof, which are the same material as the gate insulating layer 352, but are not limited thereto. An interlayer insulating layer 354 may be formed on the entire surface of the base layer 306. An interlayer dielectric layer 354 may be deposited over the top surface of the base layer 306 and / or the gate material 353.

FIG. 18I shows the step of first etching the curved section G '.

Formed in the pad section F 'and the bending section G' of the base layer 306 among the interlayer insulating layer 354, the gate insulating layer 352 and the multi-buffer layer 326 formed on the entire surface of the base layer 306 The interlayer insulating layer 354, the gate insulating layer 352, and the multi-buffer layer 326 can be etched and removed at a portion thereof.

At this time, the gate insulating layer 352 and the multi-buffer layer 326 under the upper protective metal 367 formed in the bending section G 'may not be etched. That is, the interlayer insulating layer 354 on the upper protective metal 367 formed in the bending section G 'can be etched and removed. At this time, the upper protective metal 367 formed in the bending section G 'may be exposed.

Also, the multi-buffer layer 326 under the lower protective metal 369 formed in the bending section G 'may not be etched. That is, the interlayer insulating layer 354 and the gate insulating layer 352 on the lower protective metal 369 formed in the bending section G 'can be etched and removed. At this time, the lower protective metal 369 formed in the bending section G 'may be exposed. At this time, the gate insulating layer 352 and the multi-buffer layer 326 in the region where the lower protective metal 369 is not formed in the bending section G 'are not etched because the upper protective metal 367 is formed on the upper portion .

The interlayer insulating layer 354, the gate insulating layer 352, and the multi-buffer layer 326 can be etched and removed through a mask process. The masking process may include a PR coating similar to the mask process of forming a contact hole in the active buffer 327 and the gate insulating layer 352, a process of exposing, developing, etching and PR removal through a patterning mask.

The flexibility of the bending section G 'of the flexible display device 300 can be improved when the interlayer insulating layer 354 and the gate insulating layer 352 are removed in the bending section G'.

Figure 18J shows the step of etching the underlying protective metal.

At this time, the upper protective metal 367 exposed in the pad section F 'and the bending section G' and the lower protective metal 369 exposed in the bending section G 'are etched together.

The exposed upper protective metal 367 and lower protective metal 369 may be removed by wet-etching. Accordingly, the multi-buffer layer 326 can be exposed in the bending section G '. At this time, the upper protective metal 367 in the pad section F 'may be excessively etched by wet etching. The end of the upper protective metal 367 in the pad section F 'may be formed to be positioned inside the end of the interlayer insulating layer 354 on the upper protective metal 367 in the pad section F' have.

FIG. 18K shows the step of second-order etching the bending section G '.

A part of the multi-buffer layer 326 formed in the bending section G 'can be etched and removed. At this time, the multi-buffer layer 326 formed in the bending section G 'can be uniformly removed.

The multi-buffer layer 326 may be etched and removed through a mask process. Since the mask process is the same as the mask process for forming the contact holes in the active buffer 327 and the gate insulating layer 352, the duplicate description is omitted.

The mask process for secondarily etching the bending section G 'may be performed using the same masking device as the mask process for firstly etching the bending section G'.

When the bending section G 'is secondarily etched, the multi-buffer layer 326 of the curved corrugation G' may become thinner than the multi-buffer layer 326 of the display area. Therefore, the flexibility of the bending section G 'of the flexible display device 300 can be improved.

The bending section G 'of the flexible display device 300 can be formed thinner than other regions by the first etching and the second etching.

The lower protective metal 369 disposed at the bending section G 'may act as a barrier layer between the layers formed on the upper protective metal 369 and the lower protective metal 369 have. The upper protective metal 367 may be formed on the multi-buffer layer 326 where the lower protective metal 369 is not formed in the bending section G '. At this time, the upper protective metal 367 may protect the multi-buffer layer 326 in which the lower protective metal 369 is not formed. Accordingly, the upper protective metal 367 can prevent the base layer 306 from being exposed by etching the multi-buffer layer 362 during the etching process because the lower protective metal 369 is not formed. Thus, the base layer 306 is exposed between the lower protective metal 369 and another adjacent lower protective metal 369, and foreign matter can be suppressed from being present. Thus, a short (or electrical connection) between the connection wirings 320 can be prevented.

The layers formed on the lower protective metal 369 and the layers formed on the upper protective metal 327 in the bending section G 'can be removed by etching when the bending section G' is first etched. Thereafter, a part of the upper protective metal 327 and the lower protective metal 369 are removed and then the bending section G 'is secondarily etched to form a multi-layered structure of the upper protective metal 327 and the lower protective metal 369, The buffer layer 326 can be etched.

At this time, the upper protective metal 327 and the lower protective metal 369 may serve as an etch stopper. Therefore, uniformity between the curved sections G 'can be improved by using the same mask when the curved section G' is subjected to the first etching and the second etching. Therefore, the manufacturing process of the flexible display device 300 can be simplified.

Also, the uniformity between the bending sections G 'is improved and the flexibility of the bending sections G' can be improved. Accordingly, when the connection wiring 320 formed in the bending section G 'is bent, the connection wiring 320 can be prevented from being damaged.

Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those embodiments and various changes and modifications may be made without departing from the scope of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of protection of the present invention should be construed according to the claims, and all technical ideas within the scope of equivalents should be interpreted as being included in the scope of the present invention.

100, 200, 300: flexible display device
106, 206, 306: Base layer
120, 220, 320: Connection wiring
126, 226, 326: multi-buffer layer
127, 227, 327: active buffer
128, 228, 328: protective layer
151, 251, 351: semiconductor layer
152, 252, 352: gate insulating layer
153, 253, 353: gate material
154, 254, and 354: an interlayer insulating layer
155, 255, 355: driving electrode
156, 256, 356: planarization layer
157, 257, 357: first electrode
158, 258, 358: organic light emitting layer
159, 259, 359:
160, 260, 360: bank
161, 261, 361:
162, 262, 362: sealing layer
169, 269, 369: Lower protective metal
367: Top protection metal

Claims (17)

A flexible substrate having a display region, a pad region extending in the display region, and a bending region extending in the pad region;
A first buffer layer disposed on the flexible substrate, the first buffer layer having a plurality of layers, the thickness of the bending region being thinner than the thickness of the bending region;
A first protective member disposed on the first buffer layer in the pad region;
A first insulating layer disposed on the first protection member in the pad region;
A gate wiring disposed on the first insulating layer and extending from the display region;
A second insulating layer disposed on the gate wiring in the pad region;
A connection wiring electrically connected to the gate wiring; And
And a second buffer layer covering the connection wiring,
Wherein a portion of the connection wiring is disposed on the second insulating layer in the pad region and a portion other than the one portion is disposed on the first buffer layer in the bending region. The method according to claim 1,
Wherein the first protection member is spaced apart from another adjacent first protection member. 3. The method of claim 2,
Wherein the first protective member is provided such that a part of the first insulating layer and the first buffer layer in the bending region can be removed by the same patterning equipment. The method of claim 3,
The flexible display device further includes a thin film transistor protection member disposed on the first buffer layer in the display region,
Wherein the first protection member is the same material as the thin film transistor protection member. The method according to claim 1,
Wherein the flexible display device further comprises a second protection member disposed between the first insulation layer and the second insulation layer. 6. The method of claim 5,
And the second protection member is the same material as the gate wiring. 6. The method of claim 5,
Wherein the second protection member is configured to prevent the flexible substrate from being exposed between the first protection member and the adjacent first protection member to prevent the foreign matter from being present. 8. The method of claim 7,
And the second protection member prevents another connection wiring adjacent to the connection wiring from being shorted. 6. The method of claim 5,
Wherein an end of the second protection member is located inside the end of the second insulation layer. Forming a first buffer layer having a plurality of layers on a flexible substrate having a display region, a pad region extending in the display region, and a bending region extending in the pad region;
Patterning a first protective member on a portion of the first buffer layer in the pad region and the bending region;
Forming a first insulating layer on the first buffer layer so as to cover the first protective member;
Sequentially forming a gate wiring extending from the display region and a second insulating layer covering the gate wiring on the first insulating layer;
Exposing the first protective member in the bending region;
Etching the exposed first protective member;
Forming connection wirings on the first insulating layer of the pad region and the first buffer layer of the bending region so as to be connected to the gate wiring in a manner of being electrically connected to the gate wiring; And
And forming a second buffer layer covering the connection wiring. 11. The method of claim 10,
Wherein the manufacturing method of the flexible display device further comprises etching the first buffer layer in the bending region after etching the exposed first protective member. 12. The method of claim 11,
Wherein the step of etching the first buffer layer is the same as the step of exposing the first protective member, but etching is performed using a patterning equipment. 11. The method of claim 10,
Wherein the patterning of the first protective member is performed such that the first protective member is patterned to be spaced apart from the pad region and the bending region with another adjacent first protective member. 11. The method of claim 10,
Wherein the step of forming the gate wiring includes forming a second protective member covering a portion of the first insulating layer in the pad region and the bending region. 15. The method of claim 14,
Wherein the step of exposing the first protective member comprises wet-etching the portion of the first insulating layer not covered with the second protective member in the bending area. 16. The method of claim 15,
Wherein the step of etching the exposed first protective member comprises etching the second protective member and the exposed first protective member together. 16. The method of claim 15,
The step of etching the exposed first protective member may include etching the second protective member in the pad region and the exposed first protective member together so that an end of the second protective member contacts the second insulating layer Wherein the first electrode and the second electrode are formed so as to be located on the inner side of the end.

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