KR20120073904A - Manufacturing method for flexible display device - Google Patents

Abstract

PURPOSE: A method for manufacturing a flexible display device is provided to crystallize an amorphous silicon layer to a polysilicon layer without expensive laser equipment by performing a low temperature dehydrogenation process in an active layer. CONSTITUTION: A sacrificial layer(112) is formed on a substrate(110). A polyimide film(114) is formed on the sacrificial layer. A buffer film(116) is formed on the polyimide film. An active layer(118) is formed on the buffer film. An operation layer(120) is formed on the active layer. A marking layer(122) is formed on the active layer.

Description

Manufacturing method for flexible display device

The present invention relates to a flexible display device, and more particularly, to a manufacturing method of a flexible display device capable of reducing manufacturing costs and shortening process time.

The display device is a visual information transmission medium, which visually displays data in the form of characters or figures on a CRT surface.

In general, a flat panel display (FPD) device is a thinner and lighter image display device using a TV or computer monitor CRT, which is a liquid crystal display (LCD) using liquid crystal. ), PDP (Plasma Display Panel) using gas discharge, OLED (Organic Light Emitting), which is an organic material made by using light emitting phenomenon that emits light when electric current flows in fluorescent organic compound, and charged particles in electric field are anode or cathode There is an electric paper display (EPD) using the phenomenon of moving to the side.

The most representative liquid crystal display device of a flat panel display device displays a desired image by individually supplying data signals according to image information to pixels arranged in an active matrix form to adjust light transmittance of the pixels.

The liquid crystal display includes a liquid crystal panel displaying image data input from the outside and a driving circuit for driving the liquid crystal panel.

Recently, a display device using a flexible substrate that can be bent using a substrate made of a flexible material, such as plastic, has been developed instead of a glass substrate having no flexibility.

1 is a cross-sectional view illustrating a manufacturing process of a conventional flexible display device.

Referring to FIG. 1, first, a sacrificial layer 12 made of amorphous silicon is formed on a rigid substrate 10. In this case, the non-flexible substrate 10 may be a glass substrate having no flexibility.

Subsequently, a polyimide 14 is coated on the sacrificial layer 12. In this case, the polyimide film 14 finally serves as a substrate of the flexible display device.

The buffer layer 16 is formed on the substrate 10 coated with the polyimide layer 14, and the driving layer 18 is formed on the buffer layer 16. In this case, an amorphous silicon layer is formed on the driving layer 18, the amorphous silicon layer is irradiated with a laser to crystallize into a polysilicon layer, and then patterned to form an active layer (not shown). Thereafter, a thin film transistor process is performed on the active layer to form a plurality of thin film transistors.

Next, a display panel process is performed on the driving layer 18 in accordance with the display mode of the flexible display device to form the display layer 22.

Here, when the display mode of the flexible display device is an AMOLED (Active Matrix Organic Light-Emitting Diode), an organic light emitting diode OLED is formed on the driving layer 18. In addition, when the display mode of the flexible display device is AMEPD (Active Matrix Electrophoretic Display), an electrophoretic film (Front Plane Laminate) is attached to the driving layer 18.

Subsequently, although not shown in the drawings, the substrate 10 on which the display layer 22 is formed is cut into unit panels through a cutting process, and then a module process of attaching a gate and a data tape carrier package to the unit panels is performed. In this case, a gate and a data driving chip are mounted on each gate and data tape carrier package.

Next, a laser 24 is irradiated on the back surface of the non-flexible substrate 10 to separate the polyimide film 14 serving as the substrate of the flexible substrate 10 and the flexible display device. When the laser 24 is irradiated to the back surface of the substrate 10 in this manner, a dehydrogenation reaction occurs to separate the substrate 10 and the polyimide film 14. As a result, a flexible display device using the polyimide film 14 as a substrate is manufactured.

However, in order to fabricate the flexible display device, as shown in FIG. 1, when the amorphous silicon layer is irradiated with the laser 24 and crystallized into a polysilicon layer, heat treatment is performed on the amorphous silicon layer. The sacrificial layer 12 is also dehydrogenated at the same time.

Meanwhile, in the step of detaching the sacrificial layer 12 after the module process to the unit panel, when the laser 24 is irradiated, a large amount of hydrogen is included in the sacrificial layer 12 to generate a film burst. Proceed with the disadvantage that the membrane does not occur is not separated from the substrate. Accordingly, a laser is irradiated to the amorphous silicon layer to form an active layer.

When the laser is irradiated to the amorphous silicon layer, expensive laser equipment is essential, and the process time increases because the laser is irradiated to the entire substrate.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and to provide a method of manufacturing a flexible display device that can reduce manufacturing costs and process time.

Other objects and features of the present invention will be described in the configuration and claims of the invention described below.

In order to achieve the above object, a method of manufacturing a flexible display device according to an embodiment of the present invention, forming a sacrificial layer and a polyimide film on a substrate, forming a buffer film on the polyimide film, the buffer Forming an amorphous silicon layer based on Ar on the film, irradiating the amorphous silicon layer with an excimer laser to crystallize it into a polysilicon layer, and patterning the polysilicon layer to form an active layer, the active Forming a driving layer on the layer and forming a display layer on the active layer.

In the forming of the amorphous silicon layer, the ratio of SiH 4 to Ar is set to 1:50.

The active layer contains about 2% hydrogen.

And performing a low temperature dehydrogenation process between forming the amorphous silicon layer and crystallizing the polysilicon layer.

The low temperature dehydrogenation process has a temperature range of 350 ~ 500 ℃.

The sacrificial layer includes an amorphous silicon layer based on hydrogen and a silicon nitride film formed on the amorphous silicon layer.

The buffer film is a silicon oxide film or a silicon nitride film.

The buffer film includes a silicon oxide film and a silicon nitride film formed on the silicon oxide film.

A plurality of thin film transistors are formed in the driving layer.

An organic light emitting diode (OLED) is formed or an electrophoretic film is attached to the display layer according to the display mode of the display panel.

The substrate is an inflexible substrate.

As described above, the manufacturing method of the flexible display device according to the present invention provides the effect of reducing the manufacturing cost and the process time.

1 is a cross-sectional view illustrating a manufacturing process of a conventional flexible display device.
2 to 10 are cross-sectional views illustrating a process of manufacturing a flexible display device according to an exemplary embodiment of the present invention.
11 and 12 are graphs showing simulation results according to temperature changes of a thin film transistor according to an exemplary embodiment of the present invention.

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

2 to 10 are cross-sectional views illustrating a manufacturing process of a flexible display device according to an exemplary embodiment of the present invention.

Referring to FIG. 2, first, a sacrificial layer 112 made of an amorphous silicon film is formed on the non-flexible substrate 110 to impart a supporting force to support the manufacturing process of the flexible display device. In this case, the non-flexible substrate 110 may be a glass substrate having no flexibility.

Here, as shown in FIG. 3, the sacrificial layer 112 includes, for example, an amorphous silicon film 112a and a silicon nitride film (SiNx, 112b) including a-Si: H 2 sequentially formed on the substrate 110. Can be. At this time, the thicknesses of the amorphous silicon film 112a and the silicon nitride film 112b may be formed, for example, to 500 mW.

Subsequently, a polyimide 114 is coated on the sacrificial layer 112. In this case, the polyimide film 114 may be formed to have a thickness of, for example, 20 μm. Here, the polyimide film 114 finally serves as a substrate of the flexible display device.

Referring to FIG. 4, a buffer layer 116 is formed on the substrate 110 coated with the polyimide layer 114. In this case, as illustrated in FIG. 5, the buffer layer 116 may be, for example, silicon oxide layers SiO 2 and 116a and silicon nitride layers SiNx and 116b sequentially formed on the polyimide layer 114. In addition, the buffer layer 116 may be a silicon oxide layer (SiO 2, 116a) or a silicon nitride layer (SiNx, 116b). In this case, the thickness of the silicon oxide film 116a and the silicon nitride film 116b may be, for example, 1 μm or less.

Referring to FIG. 6, an amorphous silicon layer (not shown) including a-Si: Ar is formed on the buffer layer 116 and then irradiated with an excimer laser 140 to polycrystalline the amorphous silicon layer. Crystallize into layers. Next, the polysilicon layer is patterned to form the active layer 118.

Here, when forming an amorphous silicon layer (not shown) containing a-Si: Ar, the ratio of SiH4 and Ar may be set to 1:50, for example, and a low temperature dehydrogenation process is performed before irradiating the laser to the amorphous silicon layer. You can also proceed.

When the amorphous silicon layer including a-Si: Ar is formed on the buffer layer 116 as described above, the active layer 118 contains only about 2% of hydrogen, for example, so that a low temperature dehydrogenation process is possible. Dehydrogenation can also be eliminated.

Referring to FIG. 7, the driving layer 120 is formed on the active layer 118. In this case, a plurality of thin film transistors are formed in the driving layer 120 by performing a thin film transistor process. Here, a thin film transistor process will be described with reference to FIG. 8.

Referring to FIG. 8, a gate insulating film 212 is formed on the buffer film 116 including the active layers 118a and 118b. Subsequently, a metal layer (not shown) is formed on the gate insulating layer 212 and then patterned to form a gate line 214, a gate electrode 214a, a common electrode 214b, and a common line (not shown), respectively.

Here, the storage capacitor Cst including the active layer 118b, the gate insulating layer 212, and the common electrode 214b is formed.

Subsequently, the interlayer insulating film 216 is formed on the gate line 214, the gate electrode 214a, and the common electrode 214b, and the gate insulating film 212 and the interlayer insulating film ( 216 is removed to form first and second contact holes 216a and 216b. In this case, the first contact hole 216a is a portion where a source electrode is to be formed later, and the second contact hole 216b is a portion where a drain electrode is to be formed.

Next, a metal layer (not shown) is formed on the interlayer insulating layer 216 including the first and second contact holes 216a and 216b, and then patterned to form a data line (not shown), a source and a drain electrode 218a, 218b), respectively.

Next, an insulating film 220 is formed on the source and drain electrodes 218a and 218b, and the third contact hole 220a is formed by removing the insulating film 220 so that a portion of the drain electrode 218b is exposed.

Finally, a conductive layer is formed on the insulating layer 220 including the third contact hole 220a, and patterned to form a pixel electrode 222 electrically connected to the drain electrode 218b through the third contact hole 220a. To form.

Next, a display panel process is performed on the driving layer 120 according to the display mode of the flexible display device to form the display layer 122.

Here, when the display mode of the flexible display device is AMOLED, an organic light emitting diode (OLED) is formed on the driving layer 120, and when the display mode of the flexible display device is AMEPD, an electrophoretic film (Front Plane Laminate) is used. Attach.

An embodiment of the present invention will be described for forming an organic light emitting diode OLED on the driving layer 120 with reference to FIG. 9 for convenience of description.

9, the lower electrode 302 is formed on the driving layer 120. In this case, the lower electrode 302 serves as an anode of the organic light emitting diode.

Next, the hole injection layer 304, the hole transport layer 306, the light emitting layer 308, the electron transport layer 312 and the electron injection layer 314 are sequentially formed on the lower electrode 302.

In this case, when the high voltage is applied to the hole transport layer 306 and the electron transport layer 312 has the property of flowing electricity, it may be formed of a photosensitive material, for example, TPD can be used. In addition, the hole transport layer 306 may be formed of a material such as TPD, NPD, TPAC, etc., the electron transport layer 312 may be formed of a material such as BND, PBD, BCP. Here, the light emitting layer 308 may implement various colors according to the light emitting material.

Subsequently, an upper electrode 316 is formed on the electron injection layer 314. In this case, the upper electrode 316 serves as a cathode of the organic light emitting diode.

The organic light emitting diode having the above structure may be a passive matrix OLED (PMOLED).

Subsequently, the laser 160 is irradiated on the rear surface of the non-flexible substrate 10 to separate the polyimide layer 114 serving as the substrate of the flexible substrate 110 and the flexible display device.

Referring to FIG. 10, when the laser 160 is irradiated on the back surface of the non-flexible substrate 110, a dehydrogenation reaction occurs to separate the non-flexible substrate 110 and the polyimide film 114. As a result, a flexible display device using the polyimide film 114 as a substrate is manufactured.

11 and 12 are graphs showing simulation results according to temperature changes of a thin film transistor according to an exemplary embodiment of the present invention.

11 and 12, in the exemplary embodiment of the present invention, an amorphous silicon layer including a-Si: Ar is formed on the buffer layer 116 when the active layer 118 of the thin film transistor is formed, and low-temperature dehydration is performed. After the extinguishing process, the amorphous silicon layer is irradiated with the excimer laser 140 to crystallize the amorphous silicon layer into a polysilicon layer. 10 shows a low temperature dehydrogenation process at a temperature of 470 ° C., and FIG. 11 shows a low temperature dehydrogenation process at a temperature of 380 ° C., for example.

After forming the thin film transistor as described above, by applying a predetermined voltage to the gate electrode of the thin film transistor and turning on, and measuring the current flowing through the drain electrode, it can be seen that the thin film transistor operates normally.

As described above, in one embodiment of the present invention, unlike the prior art in which the sacrificial layer 12 and the active layer are formed based on hydrogen (H), the sacrificial layer 112 is formed based on hydrogen (H). In addition, the active layer 118 is formed based on Ar, so that the sacrificial layer 112 and the active layer 118 have a difference in hydrogen content.

Accordingly, the amorphous silicon layer can be crystallized into a polysilicon layer without using a laser for dehydrogenation without using a laser for the active layer 118 and without using expensive laser equipment. In addition, the process time can be shortened by performing a low temperature dehydrogenation process on the active layer 118.

Many details are set forth in the foregoing description but should be construed as illustrative of preferred embodiments rather than to limit the scope of the invention. Therefore, the invention should not be defined by the described embodiments, but should be defined by the claims and their equivalents.

110: non-flexible substrate 112: sacrificial layer
114: polyimide film 116: buffer film
118: active layer 120: drive layer
122: display layer 140: excimer laser
302: lower electrode 304: hole injection layer
306: hole transport layer 308: light emitting layer
312: electron transport layer 314: electron injection layer
316: upper electrode

Claims (11)

Forming a sacrificial layer and a polyimide film on the substrate;
Forming a buffer film on the polyimide film;
Forming an amorphous silicon layer based on Ar on the buffer film;
Irradiating the amorphous silicon layer with an excimer laser to crystallize the polysilicon layer;
Patterning the polysilicon layer to form an active layer;
Forming a driving layer on the active layer; And
And forming a display layer on the active layer. The method of claim 1,
The forming of the amorphous silicon layer is a method of manufacturing a flexible display device, characterized in that the ratio of SiH4 and Ar is set to 1:50. The method of claim 1,
And about 2% hydrogen in the active layer. The method of claim 1,
And performing a low temperature dehydrogenation process between forming the amorphous silicon layer and crystallizing the polysilicon layer. The method of claim 4, wherein
The low temperature dehydrogenation process has a temperature range of 350 to 500 ° C. A method for manufacturing a flexible display device. The method of claim 1,
The sacrificial layer includes an amorphous silicon layer based on hydrogen; And
And a silicon nitride film formed on the amorphous silicon layer. The method of claim 1,
The buffer layer is a method of manufacturing a flexible display device, characterized in that the silicon oxide film or silicon nitride film. The method of claim 1,
The buffer film is a silicon oxide film; And
And a silicon nitride film formed on the silicon oxide film. The method of claim 1,
A plurality of thin film transistors are formed in the driving layer. The method of claim 1,
The organic light emitting diode (OLED) is formed or an electrophoretic film is attached to the display layer according to the display mode of the display panel. The method of claim 1,
And said substrate is a non-flexible substrate.

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