KR20140085954A - Flexible Display Device and Method for fabricating the same - Google Patents

Abstract

A flexible display device and a method for manufacturing the same are disclosed. The flexible display device of the present invention comprises a substrate; a first buffer layer formed on the substrate; a block buffer layer formed on the first buffer layer; a second buffer layer formed on the block buffer layer; a thin film transistor formed on the second buffer layer; a protective film and a pixel electrode formed on the second buffer layer on which the thin film transistor is formed; and a display panel disposed on the substrate on which the pixel electrode is formed. In the flexible display device according to the present invention, a carrier substrate, which is disposed under the display panel, can be easily separated by using a laser beam without damaging elements formed on the display panel.

Description

TECHNICAL FIELD [0001] The present invention relates to a flexible display device and a fabrication method thereof.

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a flexible display device, and more particularly, to a flexible display device capable of rapidly performing a desorption process without damaging a display panel when a carrier substrate, And a manufacturing method thereof.

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. An organic light emitting display (OLED) for displaying an image by controlling the amount of emitted light of the organic light emitting layer by using a flat panel display device which can reduce weight and volume, which is a disadvantage of a cathode ray tube (CRT) Paper, and so on.

In particular, an electronic paper using an organic light emitting display device and an electronic ink film is easy to be realized by a flexible display device and has been developed recently.

The organic light emitting diode display is a self-luminous element using a thin light emitting layer between electrodes. The organic light emitting display has a structure in which a plurality of pixels composed of three color (R, G, B) sub-pixels are arranged in a matrix form, a substrate on which a cell driver array and an organic light emitting array are formed is encapsulated, Thereby displaying an image.

In order to express colors in an organic light emitting display, an organic light emitting layer that emits red, green, and blue light is used. An organic light emitting layer is formed between two electrodes to form an organic light emitting diode.

In addition, an electronic paper or the like using an electronic ink film uses electrophoresis principle and is a display device that displays an image by moving by charged electric field in a state in which charged particles are injected into a fluid.

Specifically, black and white display images are realized by using microcapsules in which white fine particles having a positive charge in a transparent fluid and black fine particles having a negative charge are dispersed.

The glass light emitting display device and the electronic paper may be formed by forming a flexible plastic substrate on a carrier substrate and then forming a thin film transistor (TFT) on the plastic substrate and an organic light emitting display panel or an electronic ink film And then the carrier substrate is separated. Although the organic light emitting display panel is referred to as the organic light emitting display panel, it may be formed by laminating electrodes and light emitting layers on a substrate on which a thin film transistor is formed.

1 is a view showing a step of separating a carrier substrate in a conventional manufacturing process of a flexible display device.

Referring to FIG. 1, a sacrificial layer 11 composed of amorphous silicon (a-Si: H) and a lower substrate 20 are laminated on a carrier substrate 10 at the time of manufacturing a flexible display device.

A buffer layer 21 is formed on the lower substrate 20 and a gate electrode 22, a gate insulating film 23, a channel layer 24, source / drain electrodes 25a , And 25b are formed. A passivation layer 27 is formed on the lower substrate 20 on which the thin film transistor is formed and a pixel electrode 29 is formed on the passivation layer 27.

When the organic light emitting display device is implemented on the lower substrate 20 on which the pixel electrodes 29 are formed, the organic light emitting display panel including the organic light emitting diode electrodes and the organic light emitting layer may be formed. However, when an electronic paper is implemented, an electronic ink film (E-ink film) may be attached.

As described above, when the manufacturing process of the flexible display device is completed, a laser beam is irradiated to the back surface of the lower substrate 20 to separate the lower substrate 20 and the carrier substrate 10, do. The principle of desorption of the substrates by the sacrificial layer 11 is that the hydrogen ions of the sacrificial layer 11 are activated by the laser beam so that the lower substrate 20 and the carrier substrate 10 are separated from each other.

FIGS. 2A to 3 are views showing a phenomenon in which defects are generated in a conventional detachment process of a flexible display device.

Referring to FIGS. 2A to 3, in the laser desorption process, a laser apparatus is used. When the laser power is not constant, a thin film transistor formed on a lower substrate after a laser beam passes through the lower substrate, A problem of damaging the signal lines occurs.

Further, a strong laser beam damages the channel layer of the thin film transistor, deteriorates the performance of the thin film transistor, and causes a stain defect. FIGS. 2A and 2B show that a signal line formed on a lower substrate by a laser beam is disconnected to cause a defect (line defect), and FIG. 3 shows an example in which a laser beam is applied to an organic light emitting diode The ink film is damaged, resulting in a stain defect as a whole.

Therefore, when the lower substrate and the carrier substrate are separated using the laser beam, a process of quickly separating the substrate without damaging the elements formed on the lower substrate is required.

The present invention relates to a flexible display device capable of easily separating a carrier substrate without damaging elements formed on a display panel when a carrier substrate existing under the display panel is separated by using a laser beam, The purpose is to provide.

It is another object of the present invention to provide a method of forming a block buffer layer between a lower substrate of a display panel and a carrier substrate or between a lower substrate of a display panel and layers on which elements are formed to protect a device by a laser beam, Another object of the present invention is to provide a flexible display device and a manufacturing method thereof.

According to an aspect of the present invention, there is provided a flexible display device including: a substrate; A first buffer layer formed on the substrate; A block buffer layer formed on the first buffer layer; A second buffer layer formed on the block buffer layer; A thin film transistor formed on the second buffer layer; A protective film and a pixel electrode formed on the second buffer layer on which the thin film transistor is formed; And a display panel disposed on the substrate on which the pixel electrode is formed.

Further, a flexible display device of the present invention includes: a block buffer layer; A second buffer layer formed on the block buffer layer; A substrate formed on the second buffer layer; A first buffer layer formed on the substrate; A thin film transistor formed on the first buffer layer; A protective film and a pixel electrode formed on the first buffer layer on which the thin film transistor is formed; And a display panel disposed on the substrate on which the pixel electrode is formed.

Further, a method of manufacturing a flexible display device of the present invention includes: providing a carrier substrate; Forming a sacrificial layer on the carrier substrate; Forming a substrate on the sacrificial layer; Forming a first buffer layer, a block buffer layer, and a second buffer layer on the substrate; Forming a thin film transistor, a pixel electrode, and a display panel on the second buffer layer; And a step of irradiating a laser beam onto the back surface of the carrier substrate to separate the carrier substrate from the substrate.

INDUSTRIAL APPLICABILITY The flexible display device according to the present invention has the effect of easily separating the carrier substrate without damaging the elements formed on the display panel when the carrier substrate existing under the display panel is separated using a laser beam .

In addition, the flexible display device according to the present invention is characterized in that a block buffer layer is formed between the lower substrate of the display panel and the carrier substrate or between the lower substrate of the display panel and the layers in which the devices are formed so as to protect the device by the laser beam, There is an effect that can be done quickly.

1 is a view showing a step of separating a carrier substrate in a conventional manufacturing process of a flexible display device.
FIGS. 2A to 3 are views showing a phenomenon in which defects are generated in a conventional detachment process of a flexible display device.
4 and 5 are views showing a method of manufacturing the flexible display device according to the first embodiment of the present invention.
6 and 7 are views showing a flexible display device according to the second and third embodiments of the present invention.
8 is a view showing a structure of an organic light emitting display panel according to a related art.
9 is a view illustrating the structure of an organic light emitting display panel according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

4 and 5 are views showing a method of manufacturing the flexible display device according to the first embodiment of the present invention.

4 and 5, the flexible display device of the present invention includes a sacrificial layer 110 formed of amorphous silicon (a-Si: H) on a carrier substrate 100, A material is formed on the sacrificial layer 110 to form the substrate 120. The substrate 120 has a thin flexible property.

Then, a first buffer layer 121, a block buffer layer 130, and a second buffer layer 131 are sequentially formed on the substrate 120.

The first and second buffer layers 121 and 131 may be made of a transparent inorganic insulating material such as silicon nitride or nitride oxide. Further, it may be formed of an insulating organic material.

The first buffer layer 121 may be formed of an insulating inorganic material, the second buffer layer 131 may be formed of an insulating organic material, or vice versa.

In addition, any one of the first and second buffer layers 121 and 131 may be formed of an insulating organic material, and a colored material capable of absorbing light may be used.

The block buffer layer 130 may be formed of a metal material such as Ag, Fe, Zn, Mg, Cr, Au, Ni, Ta, Cu, Ti, Pd and Pt, Alloy, a Li-Al alloy, an Au-Pd alloy, an Au-Pt alloy, a Pt-Pd alloy a and a Pd-Ag alloy). In addition, the block buffer layer 130 may be formed of a plurality of layers.

As the colored material used in any one of the first and second buffer layers 121 and 131, a resin BM (Black Matrix) using carbon black excellent in light absorption may be used. At this time, the block buffer layer may be removed, and the block buffer layer 130 may be formed of a colored material.

Although the first and second buffer layers 121 and 131 are formed with the block buffer layer 130 interposed therebetween, the buffer layer and the block buffer layer can be formed only because the first and second buffer layers 121 and 131 are not fixed. A plurality of buffer layers may be formed on the buffer layer or a plurality of buffer layers may be formed on the lower side of the block buffer layer.

As described above, when the first buffer layer 121, the block buffer layer 130, and the second buffer layer 131 are formed on the substrate 120, the gate electrode 122, A channel layer 124, and source / drain electrodes 125a and 125b. Although not shown in the figure, signal lines including a data line for supplying a data signal and a gate line for supplying a driving signal to the thin film transistor may be formed.

When the thin film transistor is formed on the substrate 120, a passivation layer 127, which is an organic layer, is formed on the entire surface, and then a contact hole process is performed to expose a part of the drain electrode 125b. A pixel electrode 129 electrically connected to the drain electrode 125b is formed on the passivation layer 127 and a display panel is attached on the pixel electrode 129. [ In the first embodiment of the present invention, the display panel is attached to the electronic ink film 150.

Then, a laser desorption process for separating the carrier substrate 100 and the substrate 120 is performed.

The laser beam travels from the back surface of the carrier substrate 100 toward the substrate 120 and the hydrogen ions of the sacrificial layer 110 are activated by the laser beam.

In the present invention, a block buffer layer 130 is formed between the substrate 120 and the layer on which the thin film transistor and the electronic ink film 150 are formed. The laser beam is incident on the substrate 120, (150).

When the block buffer layer 130 is formed of a material reflecting the laser beam, the laser beam is reflected by the block buffer layer 130 and then travels toward the back surface of the carrier substrate 100. Accordingly, the irradiated laser beam primarily reaches the sacrificial layer 110, and the laser beam reflected from the block buffer layer 130 reaches the sacrificial layer 110. Thus, the sacrificial layer 110 Can be increased. Accordingly, the carrier substrate 100 and the substrate 120 can be quickly separated (for ease of release).

Also, when the flexible display device of the present invention uses the electronic ink film 150 as a display panel, the fact that outside light travels through a plurality of microcapsules in the electronic ink film 150 to cause light loss is referred to as a block buffer layer 130) can be prevented.

That is, in the present invention, since the block buffer layer 130 is formed between the substrate 120 and the thin film transistor, the external light is reflected by the block buffer layer 130 and then travels toward the electronic ink film 150, Can be minimized.

6 and 7 are views showing a flexible display device according to the second and third embodiments of the present invention.

6 and 7, embodiments in which the flexible display device of the present invention forms the organic light emitting display panel 250 are examples.

6, a sacrificial layer 210 and a substrate 220 are stacked on a carrier substrate 200, and a first buffer layer 221 and a block buffer layer (not shown) are formed on the substrate 220, 230 and a second buffer layer 231 are sequentially formed.

The first and second buffer layers 221 and 231 may be made of a transparent inorganic insulating material such as silicon nitride or nitride oxide. Further, it may be formed of an insulating organic material.

The first buffer layer 221 may be formed of an insulating inorganic material, the second buffer layer 231 may be formed of an insulating organic material, or vice versa.

In addition, any one of the first and second buffer layers 221 and 231 may be formed of an insulating organic material, and a colored material capable of absorbing light may be used.

The block buffer layer 230 may be formed of a metal material such as Ag, Fe, Zn, Mg, Cr, Au, Ni, Ta, Cu, Ti, Pd and Pt, Alloy, a Li-Al alloy, an Au-Pd alloy, an Au-Pt alloy, a Pt-Pd alloy a and a Pd-Ag alloy). In addition, the block buffer layer 230 may be formed of a plurality of layers.

As the colored material used in any one of the first and second buffer layers 221 and 231, a resin BM (Black Matrix) using carbon black excellent in light absorption may be used. At this time, the block buffer layer may be removed and the block buffer layer 230 may be formed of a colored material.

As described above, when the first buffer layer 221, the block buffer layer 230, and the second buffer layer 231 are formed on the substrate 220, the gate electrode 222, A channel layer 224, and source / drain electrodes 225a and 225b. Although not shown in the figure, signal lines including a data line for supplying a data signal and a gate line for supplying a driving signal to the thin film transistor may be formed.

When the thin film transistor is formed on the substrate 220, a protective film 227, which is an organic film, is formed on the entire surface, and then a contact hole process is performed to expose a part of the drain electrode 225b. A pixel electrode 229 electrically connected to the drain electrode 225b is formed on the passivation layer 227 and a display panel is attached on the pixel electrode 229. In the second and third embodiments of the present invention, The organic light emitting display panel 250 shown in FIG.

Then, a laser desorption process for separating the carrier substrate 200 and the substrate 220 is performed. The laser desorption process is the same as the desorption process described in Figs. 4 and 5.

In the present invention, a block buffer layer 230 is formed between a substrate 220 and a layer on which the thin film transistor and the OLED panel 250 are formed. The irradiated laser beam primarily reaches the sacrificial layer 210, The laser beam reflected from the block buffer layer 230 reaches the sacrifice layer 210 to increase the laser beam irradiated to the sacrifice layer 210 compared to the prior art. Accordingly, the carrier substrate 200 and the substrate 220 can be quickly separated from each other.

7, the third embodiment of the present invention is similar to the structure of FIG. 6 except that the second buffer layer 231 and the block buffer layer 230 are positioned between the substrate 220 and the sacrificial layer 210. The detailed description is the same as that of FIG. 6 and will be omitted.

However, the laser beam irradiated in the laser desorption process is reflected from the block buffer layer 230 on the sacrificial layer 210, so that the laser beam does not pass through the substrate 220. The laser beam reflected from the block buffer layer 230 passes through the sacrificial layer 210 and is irradiated with the laser beam 2 by the sacrificial layer 210 as shown in FIG.

FIG. 8 illustrates a structure of an organic light emitting display panel according to a related art, and FIG. 9 illustrates a structure of an organic light emitting display panel according to the present invention.

Referring to FIG. 8, the structure of the organic light emitting display panel can be divided into red, green, and blue organic light emitting diodes, and the organic light emitting display panels are classified according to colors emitted from the organic light emitting layers R, G, In some cases, a white organic light emitting diode can be realized by laminating red, green and blue organic light emitting layers.

First, the first electrode (anode) may be formed of first to third electrode layers 301, 302, and 303, and the first and third electrode layers 301 and 303 may be formed of a transparent conductive material such as ITO or IZO have. In addition, the second electrode layer 302 is formed of an Ag alloy. This is because Ag has a large reflectivity and a low work function and thus has a low hole inflow rate, and is laminated with a transparent conductive material having a large work function to form a first electrode (anode).

A first hole transporting layer 304 and a first hole transporting layer 305a are formed on the first electrode and a first auxiliary hole transporting layer 306a and a red And a second auxiliary hole transporting layer 306b is formed in a region corresponding to the light emitting layer.

Then, a second hole transport layer 305b is formed on the entire surface of the first and second auxiliary hole transport layers 306a and 306b. The auxiliary hole transporting layers 306a and 306b are layers added for optical optimization.

Red (R), green (G), and blue (B) organic light emitting layers are formed on the second hole transporting layer 305b, and an electron transporting layer 307 and an electron injecting layer 308 are formed on the organic light emitting layers.

A second electrode is formed of a transparent conductive material (ITO, IZO) on the electron injection layer 308 and a capping layer 310 is formed on the second electrode 309.

However, as shown in FIGS. 6 and 7, when forming a block buffer layer capable of reflecting or absorbing the laser beam on the flexible display device, a single electrode made of a transparent conductive material can be used. In the case of the flexible display device structure of FIGS. 6 and 7, the first electrode (anode) 403 of the organic light emitting display panel may be formed of a single metal layer such as ITO or IZO.

The light generated in the organic light emitting layers of FIG. 9 passes through the thin film transistor region on the substrate 220 as shown in FIGS. 6 and 7, is reflected by the lower block buffer layer 230, The light can proceed to the region of the second electrode 309 of the panel.

 INDUSTRIAL APPLICABILITY The flexible display device according to the present invention has the effect of easily separating the carrier substrate without damaging the elements formed on the display panel when the carrier substrate existing under the display panel is separated using a laser beam .

In addition, the flexible display device according to the present invention is characterized in that a block buffer layer is formed between the lower substrate of the display panel and the carrier substrate or between the lower substrate of the display panel and the layers in which the devices are formed so as to protect the device by the laser beam, There is an effect that can be done quickly.

100: carrier substrate 110: sacrificial layer
120: substrate 121: first buffer layer
130: a block buffer layer 131: a second buffer layer
123: Gate insulating film 127: Protective film
150: electronic ink film 250: organic light emitting display panel

Claims (18)

Board;
A first buffer layer formed on the substrate;
A block buffer layer formed on the first buffer layer;
A second buffer layer formed on the block buffer layer;
A thin film transistor formed on the second buffer layer;
A protective film and a pixel electrode formed on the second buffer layer on which the thin film transistor is formed; And
And a display panel disposed on the substrate on which the pixel electrode is formed.
The flexible display device according to claim 1, wherein the first and second buffer layers are transparent insulating materials such as silicon nitride or nitride oxide.
The flexible display device according to claim 1, wherein the block buffer layer is a metal reflecting a laser beam.
4. The flexible display device according to claim 3, wherein the block buffer layer is formed of any one of Ag, Fe, Zn, Mg, Cr, Au, Ni, Ta, Cu, Ti, Pd, Device.
The flexible display device according to claim 1, wherein the display panel is an organic light emitting display panel including red, green, and blue organic light emitting layers. The flexible display device according to claim 1, wherein the display panel is an electronic ink film. A block buffer layer;
A second buffer layer formed on the block buffer layer;
A substrate formed on the second buffer layer;
A first buffer layer formed on the substrate;
A thin film transistor formed on the first buffer layer;
A protective film and a pixel electrode formed on the first buffer layer on which the thin film transistor is formed; And
And a display panel disposed on the substrate on which the pixel electrode is formed.
8. The flexible display device according to claim 7, wherein the first and second buffer layers are transparent insulating materials such as silicon nitride or nitride oxide.
8. The flexible display device according to claim 7, wherein the block buffer layer is a metal reflecting the laser beam.
The flexible display device according to claim 9, wherein the block buffer layer is formed of any one of Ag, Fe, Zn, Mg, Cr, Au, Ni, Ta, Cu, Ti, Pd and Pt, Device.
The flexible display device according to claim 7, wherein the display panel is an organic light emitting display panel including red, green, and blue organic light emitting layers. The flexible display device according to claim 7, wherein the display panel is an electronic ink film. Providing a carrier substrate;
Forming a sacrificial layer on the carrier substrate;
Forming a substrate on the sacrificial layer;
Forming a first buffer layer, a block buffer layer, and a second buffer layer on the substrate;
Forming a thin film transistor, a pixel electrode, and a display panel on the second buffer layer; And
And irradiating a laser beam onto the back surface of the carrier substrate to perform a desorption process for separating the carrier substrate from the substrate.
14. The method of claim 13, wherein the first and second buffer layers are transparent insulating materials such as silicon nitride or nitride oxide.
14. The method of claim 13, wherein the block buffer layer is a metal reflecting the laser beam.
The flexible display device according to claim 15, wherein the block buffer layer is formed of any one of Ag, Fe, Zn, Mg, Cr, Au, Ni, Ta, Cu, Ti, Pd and Pt, Device manufacturing method.
14. The method of claim 13, wherein the display panel is an organic light emitting display panel including red, green, and blue organic light emitting layers.
The manufacturing method of a flexible display device according to claim 13, wherein the display panel is an electronic ink film.

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