KR101922922B1 - Method for laser cutting - Google Patents

Abstract

According to an aspect of the present invention, there is provided a laser cutting method comprising: forming an upper layer on a groove-formed intermediate layer exposing a part of a lower layer; Filling the groove with a light absorbing material for absorbing a laser beam incident on the groove; And irradiating a laser beam having a predetermined wavelength to remove a part of the upper layer formed on the light absorbing material.

Description

METHOD FOR LASER CUTTING [0002]

The present invention relates to a laser cutting method, and more particularly, to a laser cutting method for removing a part of an upper layer by irradiating a laser beam onto a multilayer substrate.

Due to the recent rapid development of semiconductor technology, the flat panel display device has increased in screen size and weight, and the performance of the flat panel display device has been improved, so that the demand of the flat panel display device has been explosively increased.

Such a flat panel display device includes a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), an electroluminescence display device (ELD ), An electrophoresis display device (EPD), and an organic light emitting display device.

Such a flat panel display device is thinner and lighter than a cathode ray tube (CRT), and has advantages of being advantageous in enlargement, and its use is increasing day by day.

On the other hand, the flat panel display is formed in a laminated structure including a plurality of thin films, and each layer is formed through a repetitive patterning process. Here, the patterning process includes a process of vapor deposition, exposure, etching, and cleaning.

A deposition process during the patterning process is a process of thinly coating a specific thin film on a substrate, and an insulating film, a semiconductor film, an electrode, and the like are formed according to the thin film material. The deposited thin film is formed with a mask pattern through an exposure process, and a portion excluding the mask pattern is removed through an etching process.

Here, the etching process widely uses wet etching, which removes a part of a thin film by using an acid-based chemical. At this time, a part of the thin film is removed as a part excluding the mask pattern by reacting with the chemical.

Hereinafter, wet etching will be described in detail with reference to FIG.

1 is a schematic view for explaining a wet etching process.

1, a wet etching process for forming a pattern on the sealing layer 140 during the manufacturing process of the organic light emitting display device will be described as an example

In the organic light emitting display, a substrate 110, a TFT layer 120, a light emitting layer 130, and an encapsulation layer 140 are sequentially stacked.

The organic electroluminescent display device forms a mask pattern on the sealing layer 140 before wet etching. More specifically, the organic light emitting display includes a PR film 150 formed of a photo-resist material on the sealing layer 140, ultraviolet light is applied to the PR film 150, To form a mask pattern.

In the wet etching, an organic electroluminescence display device in which the PR film 150 is formed under the spraying device 160 is disposed, and the etching solution is sprayed from the spraying device 160. At this time, the etching solution corresponds to an acid-based chemical reagent that chemically reacts with the sealing layer 140.

The etching solution contacts the sealing layer 140 in the region where the PR film 150 is not formed and causes a chemical reaction to remove a part of the sealing layer 140.

Since the wet etching described above is isotropic and etched at the same rate in the horizontal and vertical directions, undercuts are formed under the PR film 150, and the line width that can be etched is limited, making it difficult to form a fine pattern . In addition, wet etching has a disadvantage in that a problem of disposal of the etching solution occurs.

As described above, wet etching has many problems. In order to solve such a problem, recently, a method of directly cutting a pattern by using a laser is widely used. Hereinafter, laser etching will be described in detail with reference to FIG.

2 is a schematic view for explaining a conventional laser cutting.

2, a laser cutting process for forming a pattern on the sealing layer 140 in the manufacturing process of the organic light emitting display will be described.

In the organic light emitting display, a substrate 110, a TFT layer 120, a light emitting layer 130, and an encapsulation layer 140 are sequentially stacked. At this time, the light emitting layer 130 is formed with a groove exposing a part of the TFT layer 120.

In the conventional laser cutting method, as shown in FIG. 2A, the pattern is removed by irradiating the sealing layer 140 with a laser beam along a pattern to be removed. Since the band gap of the sealing layer 140 is smaller than that of the TFT layer 120, the laser beam irradiated on the sealing layer 140 is irradiated to the TFT layer 120 Will influence.

As a result, the conventional laser cutting method damages (a) the TFT layer 120 as shown in FIG. In order to minimize the damage of the TFT layer 120, an ultra short pulse laser is recently used. The ultra-short-wavelength laser is a method of forming a V-shaped groove using a laser beam of a short wavelength and cutting the laser beam, and thus the damage of the TFT layer 120 is relatively less than that of a laser of a long wavelength. However, the ultrasound laser may still damage the TFT layer 120, and the laser beam is irradiated several times in short, which leads to an increase in processing time.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a laser cutting method capable of preventing damage to a lower layer by a laser beam in removing a part of an upper layer in a multilayer substrate composed of a lower layer, It is a technical task.

Other features and advantages of the present invention, besides the above-mentioned aspects of the present invention, will be described hereinafter, or may be apparent to those skilled in the art from the description and the description.

In addition, other features and advantages of the present invention may be newly recognized through practice of the present invention.

According to an aspect of the present invention, there is provided a laser cutting method comprising: forming an upper layer on an intermediate layer in which a groove for exposing a part of a lower layer is formed; Filling the groove with a light absorbing material for absorbing a laser beam incident on the groove; And irradiating a laser beam having a predetermined wavelength to remove a part of the upper layer formed on the light absorbing material.

According to another aspect of the present invention, there is provided a laser cutting method comprising: forming an encapsulating layer on a light emitting layer having a groove for exposing a part of a TFT (Thin Film Transistor); Filling the groove with a light absorbing material for absorbing the laser beam so that a laser beam incident on the groove can not reach the TFT; And irradiating a laser beam having a predetermined wavelength to remove a portion of the encapsulation layer formed on the light absorbing material.

According to the present invention, since the light absorbing material is filled in the grooves formed in the intermediate layer before the laser beam is irradiated, it is possible to prevent the laser beam from reaching the lower layer, thereby minimizing damage to the lower layer.

1 is a schematic view of a conventional wet etching process.
FIGS. 2A and 2B are schematic views showing a conventional laser cutting.
3 is a view showing a damage of a TFT by a conventional laser cutting.
4A and 4B are schematic views illustrating a laser cutting according to an embodiment of the present invention.
5 is a graph showing the absorption length of pure water by wavelength.
6A to 6F are views showing a laser cutting method according to an embodiment of the present invention.

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

In describing an embodiment of the present invention, when a structure is described as being "on" or "under" another structure, such a substrate is not limited to the case where these structures are in contact with each other, It should be interpreted to include the case where the structure is interposed. However, if the terms "directly above" or "directly below" are used, these structures should be construed as limited to being in contact with each other.

Hereinafter, the laser cutting according to an embodiment of the present invention is applied to a manufacturing process of an organic light emitting display. However, the laser cutting according to one embodiment of the present invention is not limited to the manufacturing process of the organic light emitting display, and can be applied to other manufacturing processes of the flat panel display.

Furthermore, the laser cutting according to an embodiment of the present invention may be applied to a process of removing a part of the upper layer in a multilayer substrate including a lower layer, an intermediate layer and an upper layer.

4A and 4B are schematic views illustrating a laser cutting according to an embodiment of the present invention.

4A and 4B, the organic light emitting display includes a substrate 410, a TFT layer 420, a light emitting layer 430, and an encapsulation layer 450 stacked in this order.

First, the substrate 410 is made of glass, plastic, quartz, silicon, or metal, and may be made of a transparent material.

Next, the TFT layer 420 is formed on the substrate 410 and includes a semiconductor layer, a gate electrode, a source electrode, and a drain electrode although not shown in FIG. 4A.

A gate insulating film is formed between the semiconductor layer and the gate electrode. An interlayer insulating film is formed on the gate electrode and the gate insulating film.

A semiconductor layer contact hole is formed in the gate insulating film and the interlayer insulating film, and the source electrode and the drain electrode are electrically connected to the semiconductor layer through the semiconductor layer contact hole.

Next, the light emitting layer 430 is formed on the TFT layer 420 and includes an organic light emitting device OLED including a first electrode, an organic light emitting layer, and a second electrode although not shown in FIG. 4A. At this time, the organic light emitting diode OLED is electrically connected to the TFT layer 420.

More specifically, a drain contact hole exposing the drain electrode is formed in the TFT layer 420, and a first electrode of the organic light emitting diode OLED is connected to the drain electrode through the drain contact hole.

A first electrode is formed on the TFT layer 420 and is connected to the drain electrode of the TFT layer 420 through the drain contact hole. The first electrode supplies current (or voltage) to the organic light emitting layer as an anode, and defines a light emitting region having a predetermined area.

An organic light emitting layer is formed between the first electrode and the second electrode. The organic light emitting layer emits light by the combination of the holes supplied from the first electrode and the electrons supplied from the second electrode.

The second electrode is formed on the organic light emitting layer and provides electrons to the organic light emitting layer as a cathode.

A plurality of the organic light emitting devices OLED are formed in the light emitting layer 430. Each organic light emitting device OLED is spaced apart to form a groove exposing a part of the TFT layer 420. [ The exposed TFT layer 420 is electrically connected to the organic light emitting diode OLED to transmit an external electrical control signal.

Next, the sealing layer 450 is formed on the light emitting layer 430 and prevents moisture and oxygen from penetrating into the organic light emitting element OLED.

The sealing layer 450 should be partially removed in a region other than the organic light emitting device OLED, that is, the region where the grooves are formed. This is because a part of the TFT layer 420 must be opened to be electrically connected to the outside.

To this end, the laser 460 irradiates the laser beam to the sealing layer 450 and cuts it, thereby opening a part of the TFT layer 420. The TFT layer 420 thus opened can transmit an external electrical signal as a pad portion of the organic light emitting diode OLED.

Hereinafter, laser cutting capable of removing a part of the sealing layer 450 without damaging the TFT layer 420 in the organic light emitting display having the multilayer substrate structure as described above will be described in detail.

4A, the organic light emitting display device fills a groove formed in the light emitting layer 430 with a light absorbing material 440 to prevent the TFT layer 420 from being damaged by the laser beam.

Here, the light absorbing material 440 can prevent the TFT layer 420 from being damaged by the laser beam by absorbing the laser beam transmitted through the sealing layer 450. For this purpose, the absorption length of the light absorbing material 440 with respect to a laser beam having a predetermined wavelength should be less than a predetermined value.

Hereinafter, the absorption length of the DI water, for example, the light absorbing material 440 will be described with the light absorbing material 440 for convenience of explanation.

5 is a graph showing the absorption length of pure water by wavelength.

As shown in FIG. 5, the DI water shows different absorption lengths for different wavelengths. Here, the absorption length indicates the length at which all the incident laser beams are absorbed.

The shorter the absorption length, the higher the absorption rate for the laser beam of the wavelength, and the longer the absorption rate for the laser beam of the wavelength is, the lower.

For example, pure water (DI water) has an absorption length of about 1 at a wavelength of 3 mu m and an absorption length of about 20 mu m at a wavelength of 10.6 mu m, as shown in Fig. That is, pure water (DI water) is interpreted as having a higher absorption rate with respect to a wavelength of 3 μm than a wavelength of 10.6 μm.

4A and 4B, in order to prevent the laser beam transmitted through the sealing layer 450 from being absorbed by the light absorbing material 440 and reaching the TFT layer 430, the absorption length of the light absorbing material 440 Should be smaller than the thickness (b) of the light emitting layer 430.

For example, when the laser beam is generated from a CO ₂ laser having a wavelength of 10.6 μm, the absorption length of pure water is about 20 μm, which is generally smaller than the thickness b of the light-emitting layer 430, which is 30 μm to 50 μm. Accordingly, pure water can be used as the light absorbing material 440.

However, when the laser beam is generated from a YAG laser having a wavelength of 1.06 mu m, the absorption length of pure water exceeds 10 mm, and therefore is generally larger than the thickness (b) of the light emitting layer 430 of 30 mu m to 50 mu m. Thus, pure water can not be used as the light absorbing material 440.

Thus, pure water can be used as the light absorbing material 440 if the laser beam is produced from one of a CO2 laser, a 2790 nm laser, a 2900 nm laser, and a 2940 nm laser.

The depth c of the light absorbing material 440 is the same as the thickness b of the light emitting layer 430 in one embodiment shown in Figures 4A and 4B, The depth c may be smaller than the thickness b of the light emitting layer 430. At this time, the depth c of the light absorbing material 440 should be larger than the absorption length with respect to the wavelength of the laser beam.

Although DI water is described as the light absorbing material 440 in the above embodiment, the present invention does not limit the light absorbing material 440 to DI water. The light absorbing material 440 may be one of materials having an absorption length for a laser beam of a predetermined wavelength smaller than the thickness (b) of the light emitting layer 430.

FIGS. 6A through 6F are schematic views illustrating a laser cutting method according to an embodiment of the present invention.

6A, the TFT layer 420 is formed on the substrate 410, and the semiconductor layer, the gate insulating film, the gate electrode, the interlayer insulating film, the source electrode, the drain electrode, And a planarizing film are successively laminated.

The semiconductor layer and the gate electrode may be formed by laminating a predetermined metal material on the substrate 410, followed by an exposure process and an etching process. More specifically, the semiconductor layer and the gate electrode are formed by applying a photoresist (PR) to a metal material stacked on the substrate 410, exposing and developing the mask to form a mask pattern, A pattern can be formed through a so-called photolithography process in which a predetermined region of the material is etched and then the mask pattern is removed.

However, the present invention is not limited thereto. It is also possible to use a paste of a metal material, such as screen printing, inkjet printing, gravure printing, gravure offset printing, reverse offset printing the semiconductor layer and the gate electrode may be directly patterned by a printing process such as reverse offset printing, flexo printing, or microcontact printing.

The pattern forming process for each of the constitutions described below can also be performed by using a photolithography process or a printing process depending on the constituent material, and a repeated description thereof will be omitted.

A semiconductor layer contact hole is formed in the gate insulating film and the interlayer insulating film. The semiconductor layer contact hole is formed by etching the gate insulating film and the interlayer insulating film so that a part of the semiconductor layer is exposed.

The source / drain electrode is electrically connected to the semiconductor layer through the semiconductor layer contact hole, and is patterned to be spaced apart from the gate electrode.

A drain contact hole is formed in the planarization film. The drain contact hole is formed by etching a planarizing film so that a part of the drain electrode is exposed.

6B, the light emitting layer 430 is formed on the TFT layer 420 on which the planarization film is formed. The light emitting layer 430 includes an organic light emitting diode OLED including a first electrode, an organic light emitting layer, and a second electrode, not shown in FIG. 4B.

The first electrode is pattern-formed to be connected to the drain electrode through the drain contact hole. The organic light emitting layer is formed on the first electrode using thermal vacuum deposition, and is electrically connected to the first electrode. The thermal vacuum deposition causes the organic material to be incident perpendicular to the substrate 410. The second electrode is formed using thermal vacuum deposition of a predetermined metal material.

The light emitting layer 430 forms a groove exposing a part of the TFT layer 420 by disposing the organic light emitting elements OLED apart from each other.

In one embodiment, although not shown in FIG. 6B, an adhesive layer may be further formed on the light emitting layer 430 to facilitate the peeling of the sealing layer 450. Such an adhesive layer can be formed using an inorganic material such as amorphous silicon (a-Si) or silicon nitride (SiNx).

6C, an encapsulating layer 450 is formed on the light emitting layer 430. Then, as shown in FIG. An encapsulation layer 450 is formed on the entire surface of the substrate 410 to prevent moisture and oxygen from penetrating into the organic light emitting device OLED.

In one embodiment, the encapsulation layer 450 may be a film formed of polyimide.

Next, the light absorbing material 440 is filled in the groove formed in the light emitting layer 430. 6D, the substrate 410 is immersed in the light absorbing material 440 and taken out. At this time, the light absorbing material 440 is sucked into the groove by the capillary phenomenon.

On the other hand, the light absorbing material 440 is one of materials whose absorption length for the laser beam having a predetermined wavelength is smaller than the thickness of the light emitting layer 430.

6E, the laser 460 irradiates the laser beam to the encapsulating layer 450 to open a part of the TFT layer 420 to the outside. Accordingly, a part of the TFT layer 420 is opened by cutting off the sealing layer 450 in the region other than the organic light emitting device OLED, that is, the region where the grooves are formed.

In one embodiment, the wavelength of the laser beam may be set to X that satisfies the absorption length (X) < thickness (light emitting layer) of the light absorbing material. The absorption length (X) of the light absorbing material indicates the absorption length of the light absorbing material at the wavelength X, and the thickness (light emitting layer) indicates the thickness of the light emitting layer.

Next, as shown in FIG. 6F, the light absorbing material 440 filled in the groove is removed. At this time, the light absorbing material 440 may be removed using an air blower.

Although the laser cutting method is applied to the manufacturing process of the organic light emitting display device in the above embodiment, the present invention is not limited to the manufacturing process of the organic light emitting display device, and the manufacturing process of other flat panel display devices . &Lt; / RTI &gt;

Further, the laser cutting method of the present invention can be widely applied as a method of removing a part of an upper layer in a multilayer substrate including a lower layer, an intermediate layer and an upper layer.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

410: substrate 420: TFT layer
430: light emitting layer 440: light absorbing material
430: encapsulation layer 460: laser

Claims (10)

Forming an upper layer on the grooved intermediate layer exposing a portion of the lower layer;
Filling the groove with a light absorbing material for absorbing a laser beam incident on the groove; And
Irradiating a laser beam having a predetermined wavelength to remove a part of the upper layer formed on the light absorbing material,
Wherein the depth of the light absorbing material is greater than the absorption length for the laser beam. The method according to claim 1,
Wherein the light absorbing material has an absorption length for the laser beam smaller than a thickness of the intermediate layer. delete The method according to claim 1,
Wherein the light absorbing material is pure water. 5. The method of claim 4,
Wherein the laser beam is generated from one of a CO2 laser, a 2790 nm laser, a 2900 nm laser, and a 2940 nm laser. The method according to claim 1,
And blowing air into the groove to remove the light absorbing material. Forming an encapsulation layer on a light-emitting layer having grooves exposing a part of a TFT (Thin Film Transistor);
Filling the groove with a light absorbing material for absorbing the laser beam so that a laser beam incident on the groove can not reach the TFT; And
And irradiating a laser beam having a predetermined wavelength to remove a portion of the encapsulation layer formed on the light absorbing material. 8. The method of claim 7,
Wherein the light absorbing material has an absorption length of the laser beam of greater than 30 um and less than 50 um. 8. The method of claim 7,
Wherein the light absorbing material is pure water. 8. The method of claim 7,
(X) < thickness (light emitting layer) of the light absorbing material, and setting the determined X to the wavelength of the laser beam,
Wherein an absorption length (X) of the light absorbing material indicates an absorption length of the light absorbing material at a wavelength X, and the thickness (light emitting layer) indicates a thickness of the light emitting layer.

Images