KR20120063930A - Manufacturing method of flexible display device - Google Patents

Abstract

PURPOSE: A manufacturing method of a flexible display device is provided to form a coating layer on a rare side of a flexible substrate after etching a part of a rear side of the flexible substrate before forming a display device on the flexible substrate. CONSTITUTION: A coating layer(220) is formed in the rear side of a metal substrate(200) after removing a protective film on a rear side of a metal substrate. The coating layer is formed by coating a colorless transparent organic material. The coating layer planarizes the rear side of the metal substrate.

Description

Manufacturing method of flexible display device

The present invention relates to a method of manufacturing a flexible display device, and more particularly, to a method of manufacturing a flexible display device capable of reducing process efficiency and material cost.

In recent years, as the society enters a full-scale information age, a display field for processing and displaying a large amount of information has been rapidly developed, and various various flat panel display devices have been developed and are in the spotlight.

Specific examples of such a flat panel display device include a liquid crystal display device (LCD), a plasma display panel device (PDP), a field emission display device (FED), and an electroluminescent display device. (Electroluminescence Display device: ELD), etc. These flat panel display devices are rapidly replacing the existing cathode ray tube (CRT) by showing excellent performance of thin, light weight, low power consumption.

On the other hand, such a flat panel display device uses a glass substrate to withstand the high heat generated during the manufacturing process, there is a limit in providing light weight thinning and flexibility.

Therefore, recently, a flexible display device manufactured to maintain display performance even if it is bent like a paper using a flexible material such as plastic instead of a glass substrate without conventional flexibility is emerging as a next-generation flat panel display device.

However, flexible substrates are difficult to be applied to existing display equipment designed for glass or quartz substrates because of their well-curved characteristics. For example, they are transported by track equipment or robots or stored in cassettes. This impossible constraint appears.

In order to solve this problem, a technique of attaching a flexible substrate through a pressure-sensitive adhesive on a glass or quartz base substrate to proceed with the manufacturing process for a display device and then removing the flexible substrate from the base substrate at an appropriate stage has been introduced.

However, in the peeling process of the flexible substrate, the pressure-sensitive adhesive must not be completely cured during the component forming process in order to facilitate the peeling of the flexible substrate from the base substrate. For this purpose, the maximum process temperature of the component forming process is 150 ° C. or lower. Limited.

However, when a driving device such as a thin film transistor is manufactured at a low temperature of 150 ° C. or less among the plurality of components, the driving performance of the driving device is deteriorated and its driving is not stable, thereby causing a decrease in reliability of the flexible display device.

In addition, the unit price of glass or quartz used as the base substrate is increasing, causing a problem that the process cost is improved, and the process of separating the flexible substrate from the base substrate by the adhesive attached to the front surface of the base substrate is not easy, Since the separation is not completed completely, the adhesive may remain on the surface of the flexible substrate.

Therefore, an additional cleaning process must be performed to remove it.

The present invention is to solve the above problems, to provide a manufacturing method of a flexible display device that can be applied to the existing manufacturing equipment for flat panel display devices, but can exhibit the unique characteristics of a light and flexible flexible substrate after completion. Let it be a 1st objective.

Through this, the second purpose is to reduce the process cost.

In order to achieve the above object, the present invention comprises the steps of etching the rear surface of the flexible substrate, forming a first region having a first thickness and a second region having a second thickness; Forming a coating layer on a rear surface of the flexible substrate; Forming a display element for implementing an image on the flexible substrate corresponding to the second region; And separating the second region from the first region, wherein the second thickness is a thickness that provides flexibility to the flexible substrate.

In this case, the first region is formed around the edge of the second region, and the flexible substrate is made of stainless steel including iron (Fe), other metals such as chromium (Cr) and nickel (Ni). ), Aluminum (Al) series or magnesium (Mg) is a metal substrate made of any one.

In addition, before etching the flexible substrate, a protective film is attached to the rear surface of the flexible substrate corresponding to the first region, and the rear surface of the flexible substrate is etched by an etchant sprayed through a nozzle.

In this case, the rear surface of the flexible substrate is etched by dipping in a bath containing an etchant.

As described above, before forming the display element on the flexible substrate according to the present invention, by etching a part of the rear surface of the flexible substrate and forming a coating layer on the rear surface thereof, the bending layer has a bending characteristic similar to that of the glass or quartz substrate. At the same time, the overall weight of the flexible substrate can be reduced.

Therefore, there is an effect that can be applied to the existing manufacturing equipment for display devices designed for glass or quartz substrate.

In addition, such a flexible substrate has an effect of preventing the problem of deterioration of the performance of the driving device without limiting the process temperature, and has the effect of reducing the process cost by eliminating the base substrate.

In addition, since the process of separating the flexible substrate from the base substrate can be eliminated, there is an effect of bringing about the efficiency of the process, and there is also an effect of preventing the problem that the adhesive remains on the rear surface of the flexible substrate.

1 is a flowchart illustrating a manufacturing process of a flexible display device according to an exemplary embodiment of the present invention, according to a process sequence.
2A to 2H are cross-sectional views illustrating manufacturing steps of a flexible display device according to an exemplary embodiment of the present invention.
3 is a view for explaining a substrate etching process according to the present invention.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.

1 is a flowchart illustrating a manufacturing process of a flexible display device according to an exemplary embodiment of the present invention, according to a process sequence.

As illustrated, the flexible display apparatus is largely divided into a flexible substrate forming process st10, a display element forming process st30, a cutting process st40, and a peeling process st50. First, the flexible substrate forming process st10 is performed. It is a process of making a flexible substrate used in a display device manufacturing process.

Here, the flexible substrate forming process st10 is further divided into a flexible substrate etching process st11 and a flexible substrate coating process st12. Here, the flexible substrate etching step st11 is a process of etching a part of the rear surface of the flexible substrate.

In detail, the flexible substrate is formed by forming a plurality of unit cells in one large mother substrate having a first thickness and then separating them into one cell in order to increase productivity in manufacturing a display device.

In this case, each unit cell is separated at a predetermined distance, that is, a dummy region having a predetermined width is formed between neighboring unit cells.

Here, the flexible substrate is made of any one of stainless steel, aluminum (Al) series, or magnesium (Mg) including iron (Fe), other metals such as chromium (Cr) and nickel (Ni).

In addition, the first thickness of the flexible substrate is a thickness capable of imparting flexibility to the flexible substrate, and preferably has a bending characteristic similar to that of a glass or quartz substrate.

This is to facilitate handling of the flexible substrate during the manufacturing process of the flexible display device, and the first thickness may have a different value depending on the type of the flexible substrate. For example, when the flexible substrate is made of iron and stainless steel, the first thickness should be about 0.3 mm or more to facilitate handling during the process.

In this case, in the flexible substrate etching process (st11) of the present invention, only a part of the rear surface of the flexible substrate in the region corresponding to the region of the unit cell is etched so that the thickness of the substrate of the flexible substrate corresponding to the dummy region between the unit cells is equal to the first. Although the thickness is maintained as it is, the thickness of the flexible substrate corresponding to the unit cell region is etched to have a second thickness that is thinner than the first thickness.

Here, the second thickness is a thickness for providing flexibility to the flexible substrate, and finally forms a flexible substrate of the flexible display device.

In this case, when the second thickness is etched to be 70% or less of the first thickness, the second thickness may have flexibility.

Such flexible substrates can be made inflexible by maintaining the thickness of the flexible substrate corresponding to the dummy region even though the overall thickness becomes thin, thereby providing bending characteristics similar to those of glass or quartz substrates. The overall weight of the flexible substrate can be reduced.

Therefore, the flexible substrate of the present invention can be applied to existing display apparatus manufacturing equipment designed for glass or quartz substrates.

In detail, the liquid crystal display of which the development of the display device has been activated is formed on a glass substrate or a quartz substrate, and display elements such as a thin film transistor and a color filter are formed. The manufacturing equipment for the device is designed for glass and quartz substrates.

In particular, the manufacturing equipment for the display device is designed to be suitable for the bending characteristics of the glass substrate and the quartz substrate, the flexible substrate according to the present invention has a bending characteristic similar to the glass or quartz substrate thickness of the flexible substrate corresponding to the dummy region It is formed to have a first thickness.

In addition, as the overall weight is reduced, it may be applied to existing display device manufacturing equipment designed for glass or quartz substrates in the process of forming the display device on the flexible substrate.

For example, it can be transported by track equipment or robot, can be stored in a cassette, and can be applied to all processes including thin film deposition, photolithography, and etching.

The flexible substrate does not have a process temperature limitation, and solves the problem of not being able to form a driving device such as a thin film transistor at a temperature of 150 ° C. or more, which is a conventional problem of attaching the flexible substrate to a glass or quartz base substrate through an adhesive. It is possible to prevent the problem that the performance of the driving device is degraded.

In addition, the process cost can be reduced by deleting the base board, and the process of separating the flexible board from the base board can be deleted, thereby bringing about the efficiency of the process, and also preventing the problem of adhesive remaining on the back of the flexible board. Can be.

That is, the flexible display device according to the present invention can eliminate a process of adhering and peeling a separate base substrate.

Then, after etching a part of the rear surface of the flexible substrate in this way, the flexible substrate coating process (st12) is performed to the next step.

Here, the flexible substrate coating process st12 is to form a coating layer by applying a colorless transparent organic material in order to planarize the back surface of the flexible substrate.

This is because by etching only a part of the rear surface of the flexible substrate corresponding to the unit cell region, the flexible substrate is formed to have the first thickness of the unetched region and the second thickness of the etched region, so that the rear surface of the flexible substrate is formed by the first and the second substrates. It is formed to form a step by the difference of the second thickness.

That is, the rear surface of the flexible substrate is not flat. At this time, the back surface of the flexible substrate is flattened by applying a coating layer to the rear surface of the flexible substrate.

Through this, the flexible substrate of the present invention may be applied to equipment having a vacuum stage for fixing the substrate by suctioning the rear surface of the display device manufacturing equipment.

This completes the flexible substrate according to the embodiment of the present invention.

Subsequently, a display element forming process st30 is performed on the flexible substrate, and the display element forming process st30 is a thin film transistor, a pixel electrode, a gate, and various components constituting the flexible display device on the flexible substrate. It is a process of manufacturing components for image display such as data wiring and color filter layer.

For example, when the flexible display device finally forms an organic luminescence emitting device (OLED), the display device is formed into a driving and switching thin film transistor, the first and second electrodes, and the organic light emitting layer through the display device forming process st20. The organic light emitting diode is formed.

The driving and switching thin film transistor and the organic light emitting diode are encapsulated through the encapsulation substrate.

After forming the components of the display device, the flexible substrate is cut for each unit cell. As described above, in order to increase productivity in manufacturing the flexible display device, a plurality of unit cells are formed on one large mother substrate. After forming, each process is separated into one cell, which is a cutting process.

As such, after the cutting process st40 is performed, a peeling process st50 for separating the flexible substrate from the mother substrate is followed.

The cutting process (st40) and the peeling process (st50) are processes for separating unit cells from the dummy region of the mother substrate, and the unit cells cut through the cutting process (st40) and the peeling process (st50) are dummy between the unit cells. It is separated from the flexible substrate having a first thickness corresponding to the region and the coating layer applied to the rear surface thereof.

As a result, the flexible display device is completed.

As described above, the flexible substrate of the present invention has a bending characteristic similar to that of glass or quartz substrate by etching a part of the rear surface of the flexible substrate and forming a coating layer on the rear surface thereof before forming the display element. The overall weight of the flexible substrate can be reduced, and thus it can be applied to existing display manufacturing equipment designed for glass or quartz substrates.

In addition, the flexible substrate can prevent the problem of degrading the performance of the driving device without limiting the process temperature, and can reduce the process cost by eliminating the base substrate.

In addition, the process of separating the flexible substrate from the base substrate can be eliminated, thereby bringing about efficiency of the process, and also preventing the problem that the adhesive remains on the rear surface of the flexible substrate.

Hereinafter, a method of manufacturing a flexible display device according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2A to 2H are cross-sectional views illustrating manufacturing steps of a flexible display device according to an exemplary embodiment of the present invention.

First, as shown in FIG. 2A, any one of stainless steel, aluminum (Al), or magnesium (Mg) including iron (Fe), iron, and other metals such as chromium (Cr) and nickel (Ni). A metal substrate 200 having a mother substrate state of one is prepared.

Here, the metal substrate 200 has a plurality of unit cell regions A defined, and each unit cell region A is formed by being separated at a predetermined distance, that is, between adjacent unit cell regions A. It can be seen that a dummy region B having a predetermined width is formed in the substrate.

Here, the dummy region B is formed around the edge of one unit cell region A, and the dummy region B has a different width for each model and resolution, but the dummy region (B) is considered in consideration of process efficiency. In order to optimally realize the width of B), it is desirable to keep it within 22.5 ~ 42mm.

The metal substrate 200 has a first thickness d1 having inflexibility, and the bending property of the metal substrate 200 is similar to that of glass or quartz substrate.

Next, as shown in FIG. 2B, after attaching the protective film 210 to the back surface of the metal substrate 200 corresponding to the dummy region B, the back surface of the metal substrate 200 is shown in FIG. 2C. Proceed with the process of etching part of.

The etching process is etched through the etching solution 310 sprayed through the nozzle 300 on the back surface of the metal substrate 200.

In this case, after the metal substrate 200 is etched through the etching process as shown in FIG. 2D, the metal substrate 200 is protected by the protective film 210 so that the metal substrate 200 is not exposed to the etchant (310 in FIG. 2C). The first region S1 having a thickness d1 and the second region S2 having a second thickness d2 thinner than the first thickness d1 by being exposed to the etchant (310 in FIG. 2C) are provided. .

Here, the first region S1 is a region corresponding to the dummy region (B in FIG. 2C) between the unit cell regions (A in FIG. 2C), and the second region S2 is a unit cell region (A in FIG. 2C). The area corresponding to.

That is, the protective film 210 is to protect a part of the rear surface of the metal substrate 200, for this purpose, the protective film 210 is a material that is not easily damaged by the etching liquid (310 of Figure 2c) used in the etching process. Should consist of

The metal substrate 200 is etched by an etching solution (310 in FIG. 2C) containing a halogen element such as chlorine (Cl), bromine (Br), iodine (I), or iron chloride.

The protective film 210 may be made of polyethylene ethylene, poly ethylene terephthalate, or polyimide that may not react with the etching solution (310 of FIG. 2c) to etch the metal substrate 200. Poly Imide) and Teflon.

Here, the second thickness d2 is a thickness of the flexible substrate 110 (see FIG. 2G) that finally supports the display elements, and ultimately, a thickness that imparts flexibility to the metal substrate 200. The second thickness d2 for imparting a flexible characteristic may have a different value depending on the type of the metal substrate 200, preferably 70% or less of the first thickness d1.

Therefore, the metal substrate 200 of the present invention can be applied to existing display equipment manufacturing equipment designed for glass or quartz substrates.

That is, the metal substrate 200 is formed such that the thickness of the metal substrate 200 corresponding to the dummy region (B of FIG. 2C) has a first thickness d1 having a bending characteristic similar to that of glass or quartz substrate, and has an overall weight. As is reduced, it can be applied to existing display device manufacturing equipment designed for glass or quartz substrates in the process of forming a display device on the metal substrate 200 later.

In addition, the metal substrate 200 does not have a process temperature limitation, and the thin film at a temperature of 150 ° C. or more, which is a conventional problem of attaching a metal substrate through an adhesive (not shown) on a glass or quartz base substrate (not shown). The problem that a driving device such as a transistor DTr (see FIG. 2F) could not be formed can be solved, and a problem of degrading the performance of the driving device can be prevented from occurring.

Next, the protective film (210 of FIG. 2D) that is not etched from the metal substrate 200, that is, attached to the first region S1 on the rear surface of the metal substrate 200 is removed, and then the metal as shown in FIG. 2E is removed. The coating layer 220 is formed on the back surface of the substrate 200.

The coating layer 220 is formed by applying a colorless transparent organic material to the back of the metal substrate 200, the coating layer 220 is to planarize the back of the metal substrate 200.

Therefore, the metal substrate 200 is a metal substrate of the present invention even in a device equipped with a vacuum stage (not shown) for fixing the substrate by sucking the back of the substrate of the existing display device manufacturing equipment designed for glass or quartz substrate ( 200) can be applied.

As shown in FIG. 2F, a display element forming process is performed on the metal substrate 200 for each unit cell region (A of FIG. 2C), thereby forming components necessary for realizing an image.

Although not shown in the drawings, a buffer layer (not shown) is formed by depositing an inorganic insulating material such as silicon oxide (SiO 2) or silicon nitride (SiN x) on the metal substrate 200 before forming a plurality of components. It can also form more.

The reason for forming the buffer layer (not shown) on the metal substrate 200 is to improve the bonding force between the metal substrate 200 and the components.

In this case, the buffer layer (not shown) may be formed of a single layer of only silicon oxide (SiO 2) or silicon nitride (SiN x), or may be formed of silicon oxide (SiO 2) / silicon nitride (SiN x) or both by using the above-described two inorganic insulating materials. It may be formed to have a double layer structure of silicon nitride (SiNx) / silicon oxide (SiO 2).

Meanwhile, when the final display device forms an organic luminescence emitting device (OLED), the display element forming process is formed through the following process.

A driving thin film transistor DTr is formed on the metal substrate 200. For convenience of description, a minimum unit for image realization is defined as a pixel area (not shown), and the gate and data wirings (not shown) intersecting with each other. The area surrounded by).

 In each pixel area (not shown), a switching thin film transistor (not shown), a driving thin film transistor DTr, and an organic light emitting diode E are provided.

Here, the switching thin film transistor (not shown) formed in each pixel region (not shown), the driving thin film transistor DTr, and the organic light emitting diode E will be described in detail. Each pixel region (not shown) of the first substrate 101 will be described. Amorphous silicon is deposited on an amorphous silicon layer (not shown) to form an amorphous silicon layer (not shown), and the amorphous silicon layer is crystallized into a polysilicon layer (not shown) by irradiating a laser beam or heat treatment thereto.

Subsequently, a polysilicon layer (not shown) is patterned by performing a mask process to form the semiconductor layer 103 in a pure polysilicon state.

Next, silicon oxide (SiO 2) is deposited on the semiconductor layer 103 to form a gate insulating film 105.

Thereafter, a low resistance metal material, for example, aluminum (Al), aluminum alloy (AlNd), copper (Cu), or a copper alloy is deposited on the gate insulating layer 105 to form a first metal layer (not shown). The mask process is performed to form a gate electrode 107 and a gate wiring (not shown) corresponding to the center of the semiconductor layer 103.

Next, the dopant, i.e., the trivalent element or pentavalent element, is doped on the entire surface of the metal substrate 200 using the gate electrode 107 as a blocking mask, thereby impurity in the portion of the semiconductor layer 103 located outside the gate electrode 107. The doped source and drain regions 103b and 103c are formed, and the portion corresponding to the doped gate electrode 107 forms the active region 103a of pure polysilicon.

Next, an inorganic insulating material such as silicon nitride (SiNx) or silicon oxide (SiO 2) is deposited on the entire surface of the metal substrate 200 on which the semiconductor layer 103 is formed to form a first interlayer insulating layer 109a on the entire surface, and a mask process The first and second semiconductor layers exposing the source and drain regions 103b and 103c of the semiconductor layer 103 by simultaneously or collectively patterning the first interlayer insulating film 109a and the lower gate insulating film 105. The contact hole 116 is formed.

Subsequently, one of a metal material such as aluminum (Al), aluminum alloy (AlNd), copper (Cu), copper alloy, chromium (Cr), and molybdenum (Mo) is deposited on the first interlayer insulating layer 109a. Source and drain electrodes 110a and 110b contacting the source and drain regions 103b and 103c through the first and second semiconductor layer contact holes 116 by forming a metal layer (not shown) and patterning by performing a mask process. ) And form data wiring (not shown).

In this case, the semiconductor layer 103, the gate insulating layer 105, the gate electrode 107, and the first interlayer insulating layer 109a are separated from each other and the source and drain electrodes 110a and 110b form a driving thin film transistor DTr.

Next, an organic insulating material such as photo acryl or benzocyclobutene (BCB) is coated on the metal substrate 200 having the source and drain electrodes 110a and 110b formed thereon, and patterned through a mask process. An interlayer insulating film 109b is formed.

In this case, the second interlayer insulating film 109b has a drain electrode contact hole 117 exposing the drain electrode 110b.

Next, an anode is formed on the second interlayer insulating layer 109b to contact the drain electrode 110b through the drain contact hole 117 and form an organic light emitting diode E. One electrode 111 is formed.

Next, the first electrode 111 is coated on the first electrode 111 by applying one of photosensitive organic insulating materials, for example, black resin, graphite powder, gravure ink, black spray, and black enamel, and patterning the same. The bank 119 is formed above.

The bank 119 is formed in a matrix type having a lattice structure as a whole to distinguish between pixel regions (not shown).

Next, the organic light emitting layer 113 is formed by applying or depositing an organic light emitting material on the bank 119.

Next, the organic light emitting diode E is formed by forming a second electrode 115 having a thick transparent conductive material deposited on the translucent metal film having a thin work function deposited on the organic light emitting layer 113. You are done.

In the pixel region (not shown), hundreds to thousands are provided in one unit cell region (A of FIG. 2C).

In addition, the unit cell region (A of FIG. 2C) is encapsulated through the encapsulation film 120 of the flexible material, and the metal substrate 200 corresponding to the unit cell region (A of FIG. 2C) is formed. The driving elements form a panel state.

 Next, as shown in FIG. 2G, the unit pattern 100a constituting the panel state is cut for each unit pattern 100a as encapsulated, and the unit of the panel state from the metal substrate 200 having the mother substrate form. The pattern 100a is peeled off.

As a result, as shown in FIG. 2H, each unit pattern has the flexible substrate 110 having the second thickness d2, thereby completing the flexible display device 100 capable of maintaining the display performance even when bent like paper. do.

On the other hand, the etching process of the metal substrate 200 by the etchant (310 in Fig. 2c), in addition to the method of spraying through the nozzle (300 in Fig. 2c), as shown in Figure 3 the tank 320 containing the etchant (310) ) May be etched by dipping a portion of the back surface of the metal substrate 200.

As described above, the flexible substrate (110 of FIG. 2H) of the present invention, after forming a portion of the back surface of the flexible substrate (110 of FIG. 2H) before forming the display element, and then coated a coating layer (220 of FIG. 2G) on the rear surface thereof. By forming, it is possible to reduce the overall weight of the flexible substrate (110 in FIG. 2H) while having a bending characteristic similar to that of the glass or quartz substrate.

Therefore, the present invention can be applied to existing display apparatus manufacturing equipment designed for glass or quartz substrates.

In addition, the flexible substrate (110 of FIG. 2H) does not have a process temperature limitation, thereby preventing a problem of deteriorating the performance of the driving device, and reducing the process cost by removing the base substrate (not shown). have.

In addition, the process of separating the flexible substrate (110 in FIG. 2H) from the base substrate (not shown) can be eliminated to bring about the efficiency of the process, and the adhesive remains on the back of the flexible substrate (110 in FIG. 2H). Problems can also be prevented.

The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

200: metal substrate, 220: coating layer
d1: first thickness, d2: second thickness, S1: first region, S2: second region

Claims (6)

Etching the rear surface of the flexible substrate to form a first region having a first thickness and a second region having a second thickness;
Forming a coating layer on a rear surface of the flexible substrate;
Forming a display element for implementing an image on the flexible substrate corresponding to the second region;
Separating the second region from the first region
Wherein the second thickness is a thickness that imparts flexibility to the flexible substrate.
The method of claim 1,
And the first region is formed to surround an edge of the second region.
The method of claim 1,
The flexible substrate is made of any one of stainless steel, aluminum (Al) series, or magnesium (Mg) including iron (Fe), iron, and other metals such as chromium (Cr) and nickel (Ni). Method of manufacturing an flexible display device.
The method of claim 1,
And attaching a protective film to a rear surface of the flexible substrate corresponding to the first region before etching the flexible substrate.
The method of claim 1,
And a back surface of the flexible substrate is etched by an etchant sprayed through a nozzle.
The method of claim 1,
And a backside of the flexible substrate is etched by dipping into a bath containing an etchant.

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