KR102589657B1 - Plastic substrate, Display device including the plastic substrate, and Method of fabricating the display device - Google Patents

Abstract

The present invention relates to a plastic substrate, a display device including the same, and a manufacturing method thereof. A plastic substrate containing inorganic particles prevents thermal deformation during the process and improves optical properties by removing the inorganic particles after the process, and a display containing the same. Provides a device and its manufacturing method.
Therefore, deformation of the display device is prevented and display quality does not deteriorate.

Description

Plastic substrate, display device including the plastic substrate, and method of fabricating the display device}

The present invention relates to a display device, and more specifically, to a plastic substrate having excellent optical properties, a display device including the same, and a method of manufacturing the display device.

As society has entered a full-fledged information age, the display field, which processes and displays large amounts of information, has developed rapidly, and in response to this, liquid crystal display devices (LCDs) and organic light emitting displays (OLEDs) have developed rapidly. Various flat panel display devices such as Light Emitting display device (OLED) have been developed and are receiving attention.

For example, a liquid crystal display device includes as its essential components a liquid crystal panel including an upper substrate and a lower substrate bonded with a liquid crystal layer containing liquid crystal molecules in between, and is generated by an electric field formed between the pixel electrode and the common electrode. The liquid crystal layer is driven to display an image.

Additionally, an organic light emitting display device includes a light emitting diode including an anode and a cathode facing each other with an organic light emitting layer in between, and this light emitting diode is formed on a substrate. In an organic light emitting display device, holes and electrons injected from each of the anode and cathode combine in the organic light emitting layer to emit light, thereby displaying an image.

Meanwhile, recently, the demand for flexible display devices using flexible substrates such as plastic substrates is increasing. Flexible display devices are portable in a folded state and display images in an unfolded state, so they have the advantage of being able to display on a large screen and being easy to carry.

Such a plastic substrate has excellent optical properties, such as optical isotropy, so as not to deteriorate the display quality of the display device.

However, in manufacturing such flexible display devices, the plastic substrate used to have flexible characteristics is difficult to apply to conventional display device manufacturing equipment that processes glass substrates due to its weak heat resistance.

To overcome this problem, the process is carried out by attaching a plastic substrate to one side of a carrier substrate, such as a glass substrate, and after the process is completed, the plastic substrate is released from the carrier substrate to manufacture a display device.

However, the plastic substrate has a higher coefficient of thermal expansion (CTE) than the glass substrate, which is a carrier substrate, and a problem occurs in which the plastic substrate bends during the process.

In plastic substrates, thermal properties such as coefficient of thermal expansion and optical properties such as optical isotropy are in a trade-off relationship. In other words, increasing the thermal properties of the plastic substrate deteriorates the optical properties.

As described above, in conventional plastic substrates, there is a trade-off relationship between thermal properties and optical properties. Therefore, when optical properties are improved to improve display quality, thermal properties deteriorate, for example, the coefficient of thermal expansion increases, causing a problem of bending of the plastic substrate during the manufacturing process of the display device. Meanwhile, if the thermal expansion coefficient of the plastic substrate is lowered to solve this problem, optical isotropy is broken and the display quality of the display device deteriorates.

The present invention seeks to solve both problems during the manufacturing process due to thermal characteristics and display quality due to optical characteristics.

In order to achieve the above object, the plastic substrate according to the present invention includes a base and pores within the base.

In addition, the plastic substrate of the present invention further includes a second base that is located on one side of the first base and does not have pores, and the second base may have a thickness smaller than that of the first base.

Additionally, the present invention provides a display device having the above-described plastic substrate.

In addition, a method of manufacturing a display device is provided in which a display device is formed using a plastic substrate including a base having inorganic particles, and then the inorganic particles are removed.

The plastic substrate according to the present invention has a low coefficient of thermal expansion due to the inclusion of inorganic particles during the manufacturing process, and has a low haze value due to the inorganic particles being removed after the manufacturing process.

In addition, in the plastic substrate according to the present invention, the optical/mechanical properties of the plastic substrate are improved by laminating a first base including pores and a second base having a low retardation value (optical isotropy) and high rigidity.

Therefore, it is possible to prevent the problem of bending of the plastic substrate during the manufacturing process and the problem of deterioration of display quality in the display device.

1 is a schematic cross-sectional view of a plastic substrate according to a first embodiment of the present invention.
2A to 2E are schematic cross-sectional views for explaining the manufacturing process of a display device using a plastic substrate according to the first embodiment of the present invention.
Figure 3 is a schematic cross-sectional view of a plastic substrate according to a second embodiment of the present invention.
4A to 4E are schematic cross-sectional views illustrating a manufacturing process of a display device using a plastic substrate according to a second embodiment of the present invention.
Figure 5 is a schematic cross-sectional view of a display device according to a third embodiment of the present invention.
Figure 6 is a schematic cross-sectional view of a display device according to a fourth embodiment of the present invention.
Figure 7 is a schematic cross-sectional view of a display device according to a fifth embodiment of the present invention.

The present invention provides a plastic substrate including a first base and a plurality of pores in the first base.

The plastic substrate of the present invention further includes a second base that is located on one side of the first base and does not have pores.

In the plastic substrate of the present invention, the first and second bases are made of the same polyimide.

In the plastic substrate of the present invention, the first base has a first thickness, and the second base has a second thickness that is smaller than the first thickness.

The plastic substrate of the present invention further includes a third base containing inorganic particles and positioned between the first and second bases.

In the plastic substrate of the present invention, the third base has a thickness smaller than that of the first base.

From another perspective, the present invention provides a display device including the above-described plastic substrate and a light emitting diode located on the plastic substrate.

From another perspective, the present invention includes first and second substrates facing each other, a pixel electrode located on the first substrate, a common electrode located on any one of the first and second substrates, and the first substrate. A display device is provided, including a liquid crystal layer positioned between first and second substrates, wherein at least one of the first and second substrates is the plastic substrate described above.

From another perspective, the present invention includes a first substrate, a display element located on the first substrate, a touch element located on the display element, and the above-described plastic substrate located on the touch element. Provides a display device that

From another perspective, the present invention includes the steps of attaching a base having inorganic particles to a carrier substrate, forming a display element on the base, and separating the base on which the display element is formed from the carrier substrate; , providing a method of manufacturing a display device including the step of removing the inorganic particles from the separated base.

In the method of manufacturing a display device of the present invention, the base may include a first base containing the inorganic particles and a second base without the inorganic particles, and the first base may be in contact with the carrier substrate. .

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

1 is a schematic cross-sectional view of a plastic substrate according to a first embodiment of the present invention.

As shown in FIG. 1, the plastic substrate 100 according to the first embodiment of the present invention includes a base 110 and a plurality of pores 112 located within the base 110.

The base 110 is made of polyimide. For example, the base 110 may be made of polyimide that is transparent and has a small retardation value.

The pores 112 are formed by removing inorganic particles present in the base 110, and may have a diameter of about 1 nm to 10 μm.

Meanwhile, the inorganic particles are removed after forming the display element on the plastic substrate 100, but the inorganic particles in the base 110 are not completely removed and the inorganic particles are on one side, for example, the upper side, of the base 110. may remain.

In this case, the plastic substrate 100 consists of a base 110, pores 112, and inorganic particles (not shown).

The polyimide forming the base has excellent optical properties (optical isotropy) but poor thermal properties. That is, the polyimide has a high coefficient of thermal expansion. Meanwhile, the plastic substrate containing the inorganic particles has a low coefficient of thermal expansion.

That is, the base of the polyimide has a first coefficient of thermal expansion, the plastic substrate containing inorganic particles has a second coefficient of thermal expansion smaller than the first coefficient of thermal expansion, and the plastic substrate of the present invention includes the pores 112. (100) has a third coefficient of thermal expansion that is greater than the second coefficient of thermal expansion and is substantially the same as the first coefficient of thermal expansion.

Meanwhile, a plastic substrate containing inorganic particles has a high haze value. That is, the base of the polyimide has a first haze value, the plastic substrate containing inorganic particles has a second haze value greater than the first haze value, and the plastic substrate of the present invention includes the pores 112. (100) has a third haze value that is less than the second haze value and is substantially equal to the first haze value.

That is, adding inorganic particles to the base of polyimide with a high thermal expansion coefficient lowers the thermal expansion coefficient, while the haze value increases due to the inorganic particles.

In the present invention, the problem of bending of the plastic substrate during the manufacturing process is prevented by using a plastic substrate containing inorganic particles in the manufacturing process of the display device or display element, and the inorganic particles are removed after the manufacturing process of the display device or display element. Improves display quality by lowering the haze value.

2A to 2E are schematic cross-sectional views for explaining the manufacturing process of a display device using a plastic substrate according to the first embodiment of the present invention.

As shown in FIG. 2A, the base 110 on which the inorganic particles 114 are dispersed is attached to the carrier substrate 130. Although not shown, a sacrificial layer may be located between the base 110 and the carrier substrate 130. The carrier substrate 130 may be a glass substrate.

The inorganic particles 114 are any one of SiO ₂ (silica), TiO ₂ (titania), Al ₂ O ₃ (alumina), ZrW ₂ O ₈ (Zirconium tungstate), ZrO ₂ (Zirconia), and ZnO (Zinc oxide). It can be. The particle size according to the type of the inorganic particles 114 and the etchant used to remove the inorganic particles 114 in the subsequent process are listed in Table 1 below.

[Table 1]

The base 110 may be made of polyimide with excellent optical properties, that is, optical isotropy. That is, the base 110 is made of polyimide with a small retardation value. For example, the base 110 is made optically isotropic by using a moiety that can widen the chain spacing of polyimide.

As described above, the optical properties and thermal properties of polyimide are in a trade-off relationship, and the base 110 has a high coefficient of thermal expansion.

However, the thermal expansion coefficient of the base 110 in which the inorganic particles 114 are dispersed decreases.

Next, as shown in FIG. 2B, the display element 140 is formed on the base 110 attached to the carrier substrate 130. For example, the display element 140 may be an array element of a liquid crystal display device including a thin film transistor, a light emitting diode device of an organic light emitting display device including a light emitting diode, or a touch panel device including a touch electrode (or wiring). It may be a device.

The formation process of the display element 140 is performed at a relatively high temperature. At this time, since the base 110 containing the inorganic particles 114 has excellent thermal properties, that is, a low coefficient of thermal expansion, problems such as bending of the base 110 do not occur during the process of forming the display element 140.

Next, as shown in FIG. 2C, after the forming process of the display element 140, the carrier substrate 130 and the base 110 are detached (or separated). For example, by irradiating a laser, the desorption process of the base 110 may proceed through chemical or physical changes in the sacrificial layer (not shown) between the carrier substrate 130 and the base 110.

Next, as shown in FIG. 2D, the base 110 on which the display element 140 is formed is dipped into a container containing an etchant 150 capable of removing the inorganic particles 114. I order it.

The etchant may vary depending on the type of inorganic particles 114. For example, when SiO ₂ particles are used, an etchant containing a mixture of dispersion and ammonium fluoride may be used.

By this dipping process, the inorganic particles 114 in the base 110 are removed, and as shown in Figure 2e, the plastic substrate 100 consisting of the base 110 and the pores 112 therein is formed. can be obtained.

Meanwhile, in addition to the dipping process shown in FIG. 2D, the inorganic particles 114 are removed by a dropping process in which the etchant is dropped on the base 110, and a spray process in which the etchant is sprayed on the base 110. It can be. Although not shown, a cleaning process using pure water (DI water) may be performed after the removal process of the inorganic particles 114.

In the case of the base 110 on which the pores 112 are formed, the optical properties are improved by removing the inorganic particles 114. That is, compared to the base 110 including the inorganic particles 114, the haze value of the plastic substrate 100 including the base 110 on which the pores 112 are formed is greatly reduced. Therefore, the plastic substrate 100 can be used in a display device.

Meanwhile, as the inorganic particles 114 are removed, the thermal expansion coefficient of the plastic substrate 100 increases. However, since the inorganic particles 114 are removed after the display element 140 forming process, the increase in the thermal expansion coefficient of the plastic substrate 100 does not affect the manufacturing process of the display device.

The characteristics of the polyimide plastic substrate (#1), the plastic substrate (#2, #3) containing inorganic particles (SiO ₂ ), and the plastic substrate (#4) consisting of a base from which the inorganic particles were removed and pores were formed. It is listed in Table 2 below.

[Table 2]

As shown in Table 2, when inorganic particles are added (or dispersed) to the polyimide base, the coefficient of thermal expansion (CTE) decreases. (#2, #3) However, the haze value increases with the addition of inorganic particles.

In the case of polyimide substrates to which inorganic particles are added in this way, the problem of substrate warping during high-temperature manufacturing processes is prevented, but it is difficult to use them in display devices due to the large haze value.

However, in the present invention, after the manufacturing process of the display device, the inorganic particles are removed and the polyimide base with pores is formed to form a plastic substrate, and the haze value of the plastic substrate is reduced. (#4) Additionally, even if the inorganic particles are removed, optical isotropy (R _th ) is substantially maintained.

Therefore, the plastic substrate 100 of the present invention can be used in a display device without deteriorating display quality.

However, compared to a polyimide substrate without pores or a polyimide substrate containing inorganic particles 114, the plastic substrate 100 of a polyimide base 110 in which the inorganic particles 114 are removed and pores 112 are formed. The stiffness (modulus) decreases.

Figure 3 is a schematic cross-sectional view of a plastic substrate according to a second embodiment of the present invention.

As shown in FIG. 3, the plastic substrate 200 according to the second embodiment of the present invention includes a first base 210 including a plurality of pores 212 and a second base 210 located on the base 210. Includes base 220.

The first and second bases 210 and 220 are made of the same material, and the second base 220 does not have pores.

The first and second bases 210 and 220 are made of polyimide. For example, the first and second bases 210 and 220 may be made of polyimide, which is transparent and has a small retardation value.

The pores 212 are formed by removing inorganic particles present in the first base 210, and may have a diameter of about 1 nm to 10 μm.

The polyimide forming the first and second bases 210 and 220 has excellent optical properties (optical isotropy) but poor thermal properties. That is, the polyimide has a high coefficient of thermal expansion. Meanwhile, the plastic substrate containing the inorganic particles has a low coefficient of thermal expansion.

That is, the base of the polyimide has a first coefficient of thermal expansion, the base containing inorganic particles has a second coefficient of thermal expansion that is smaller than the first coefficient of thermal expansion, and the second base 220 and the pores 212 The first base 210 includes a third thermal expansion coefficient that is greater than the second thermal expansion coefficient and is substantially the same as the first thermal expansion coefficient.

Meanwhile, the second base 220 has a greater modulus value than the first base 210. That is, since inorganic particles are removed in the first base 210 and pores 212 are formed, the modulus value of the first base 210 decreases, and the rigidity of the plastic substrate made only of the first base 210 decreases. It deteriorates. However, in the plastic substrate 200 according to the second embodiment of the present invention, the second base 220, which does not include pores, is laminated on the first base 210, so the rigidity of the plastic substrate 220 is improved. .

At this time, the first base 210 has a first thickness t1, and the second base 220 has a second thickness t2 that is smaller than the first thickness t1. For example, the first thickness (t1) may be about 1 to 10㎛, the second thickness (t2) may be about 2 to 20㎛, and the first thickness (t1) may be about 2 to 20㎛. It can be twice (t2).

When the second base 220 has a large thickness t2, the rigidity (modulus value) of the plastic substrate 200 is improved. However, since the second base 220 has a high coefficient of thermal expansion, when the thickness t2 of the second base 220 increases, the coefficient of thermal expansion of the plastic substrate 200 increases, causing the plastic substrate to be used in the manufacturing process of the display device. (200) bending problem occurs. Accordingly, in the plastic substrate 200 of the present invention, the second base 220 has a thickness smaller than the first base 210.

Meanwhile, the inorganic particles are removed after forming the display element on the plastic substrate 200, but the inorganic particles in the first base 210 are not completely removed and the first base adjacent to the second base 220 is not completely removed. Inorganic particles may remain on the upper side of (210).

In this case, the plastic substrate 200 has a first base 210 including pores 212, a second base 220 without pores, and a space between the first and second bases 210 and 220. It may be composed of a third base (not shown) that is located and includes inorganic particles (not shown). The third base may have a thickness smaller than the first thickness t1 of the first base 210 and a second thickness t2 of the second base 220.

Meanwhile, a polyimide base containing inorganic particles has a high haze value. That is, the base of the polyimide has a first haze value, the base containing inorganic particles has a second haze value greater than the first haze value, and the second base 220 and the pores 212 The first base 210 included has a third haze value that is smaller than the second haze value and is substantially the same as the first haze value.

That is, adding inorganic particles to the first base 210 of polyimide having a high thermal expansion coefficient lowers the thermal expansion coefficient, while the haze value of the first base 210 increases due to the inorganic particles.

In the present invention, the problem of bending of the plastic substrate during the manufacturing process is prevented by using a plastic substrate containing inorganic particles in the manufacturing process of the display device or display element, and the inorganic particles are removed after the manufacturing process of the display device or display element. Improves display quality by lowering the haze value.

Additionally, the rigidity of the plastic substrate 200 increases due to the second base 220 that does not include pores.

4A to 4E are schematic cross-sectional views illustrating a manufacturing process of a display device using a plastic substrate according to a second embodiment of the present invention.

As shown in FIG. 4A, the first base 210 in which the inorganic particles 214 are dispersed and the second base 220 without the inorganic particles are sequentially attached to the carrier substrate 230. Although not shown, a sacrificial layer may be located between the first base 210 and the carrier substrate 230. The carrier substrate 230 may be a glass substrate.

The inorganic particles 214 are any one of SiO ₂ (silica), TiO ₂ (titania), Al ₂ O ₃ (alumina), ZrW ₂ O ₈ (Zirconium tungstate), ZrO ₂ (Zirconia), and ZnO (Zinc oxide). It can be.

The first and second bases 210 and 220 may be made of polyimide with excellent optical properties, that is, optical isotropy. That is, the first and second bases 210 and 220 are made of polyimide with a small retardation value. For example, the first and second bases 210 and 220 are made optically isotropic by using a moiety that can widen the chain spacing of polyimide.

As described above, the optical properties and thermal properties of polyimide are in a trade-off relationship, and the first and second bases 210 and 220 have a high coefficient of thermal expansion.

However, since the inorganic particles 214 are dispersed in the first base 210 and the second base 220 has a smaller thickness than the first base 210, the overall coefficient of thermal expansion decreases.

Next, as shown in FIG. 4B, the display element 240 is formed on the second base 210. For example, the display element 240 may be an array element of a liquid crystal display device including a thin film transistor, a light emitting diode device of an organic light emitting display device including a light emitting diode, or a touch panel device including a touch electrode (or wiring). It may be a device.

The formation process of the display element 240 is performed at a relatively high temperature. At this time, since the first base 210 containing the inorganic particles 214 has excellent thermal properties, that is, a low coefficient of thermal expansion, the first and second bases 210 and 220 are bent during the process of forming the display element 240. Problems like this do not occur.

Next, as shown in FIG. 4C, after the forming process of the display element 240, the first and second bases 210 and 220 are detached (or separated) from the carrier substrate 230. For example, by irradiating a laser, the first and second bases 210 and 220 undergo chemical or physical changes in the sacrificial layer (not shown) between the carrier substrate 230 and the first base 210. The desorption process may proceed.

Next, as shown in FIG. 4D, the first base 210 on which the display element 240 is formed is dipped into a container containing an etchant 250 capable of removing the inorganic particles 214. Dipping.

The etchant may vary depending on the type of inorganic particles 214. For example, when SiO ₂ particles are used, an etchant containing a mixture of dispersion and ammonium fluoride may be used.

By this dipping process, the inorganic particles 214 in the first base 210 are removed, and as shown in FIG. 4E, a plastic substrate consisting of the base 210 and the pores 212 therein is formed ( 200) can be obtained.

As described above, in addition to the dipping process, the inorganic particles 214 are formed by a dropping process in which the etchant is dropped on the first base 210 and a spray process in which the etchant is sprayed on the first base 210. can be removed. Although not shown, a cleaning process using pure water (DI water) may be performed after the removal process of the inorganic particles 214.

In the case of the first base 210 in which the pores 212 are formed, the optical properties are improved by removing the inorganic particles 214. That is, compared to the case including the inorganic particles 214, the haze value of the first base 110 on which the pores 212 are formed is greatly reduced. Therefore, the plastic substrate 200 can be used in a display device.

Meanwhile, as the inorganic particles 214 are removed, the thermal expansion coefficient of the second base 210 increases. However, since the inorganic particles 214 are removed after the display element 240 forming process, the increase in the thermal expansion coefficient of the first base 210 does not affect the manufacturing process of the display device.

In addition, the rigidity of the plastic substrate 200 increases and optical properties improve due to the low phase difference second base 220 without pores.

A plastic substrate (#5) consisting of a first base containing inorganic particles (SiO ₂ ) and a second base without inorganic particles, a first base with pores formed by removing inorganic particles, and a second base without pores. The characteristics of the plastic substrate (#6) are listed in Table 3 below.

[Table 3]

As shown in Table 3, compared to the polyimide base without inorganic particles (#1 in Table 1), the coefficient of thermal expansion (CTE) decreases when inorganic particles are added (or dispersed) to the first base. . (#5)

In the case of polyimide substrates to which inorganic particles are added in this way, the problem of substrate warping during high-temperature manufacturing processes is prevented, but it is difficult to use them in display devices due to the large haze value.

However, in the present invention, after the manufacturing process of the display device, a first base of polyimide in which inorganic particles are removed and pores are formed and a second base with a low haze value form a plastic substrate, and the haze value of the plastic substrate decreases. do. (#6) Additionally, even if the inorganic particles are removed, the optical isotropy (R _th ) is substantially maintained.

Additionally, the modulus value of the plastic substrate is greatly increased by the second base.

Therefore, the plastic substrate 200 of the present invention can be used in a display device while maintaining mechanical properties without deteriorating display quality.

Figure 5 is a schematic cross-sectional view of a display device according to a third embodiment of the present invention.

As shown in FIG. 5, the display device 300 includes a plastic substrate 310, a thin film transistor (Tr) located on the plastic substrate 310, and a thin film transistor (Tr) located on the upper part of the plastic substrate 310. It includes a light emitting diode (D) connected to a transistor (Tr). That is, the display device 300 according to the third embodiment of the present invention is a light emitting diode display device.

More specifically, a buffer layer 320 is formed on the plastic substrate 310, and a thin film transistor (Tr) is formed on the buffer layer 320. The buffer layer 320 may be omitted.

A semiconductor layer 322 is formed on the buffer layer 320. The semiconductor layer 322 may be made of an oxide semiconductor material or polycrystalline silicon.

When the semiconductor layer 322 is made of an oxide semiconductor material, a light blocking pattern (not shown) may be formed under the semiconductor layer 322, and the light blocking pattern prevents light from entering the semiconductor layer 322. This prevents the semiconductor layer 322 from being deteriorated by light. Alternatively, the semiconductor layer 322 may be made of polycrystalline silicon, and in this case, both edges of the semiconductor layer 322 may be doped with impurities.

A gate insulating film 324 made of an insulating material is formed on the semiconductor layer 322. The gate insulating film 324 may be made of an inorganic insulating material such as silicon oxide or silicon nitride.

A gate electrode 330 made of a conductive material such as metal is formed on the gate insulating film 324 corresponding to the center of the semiconductor layer 322.

In FIG. 5 , the gate insulating film 324 is formed on the entire surface of the plastic substrate 310, but the gate insulating film 324 may be patterned to have the same shape as the gate electrode 330.

An interlayer insulating film 332 made of an insulating material is formed on the gate electrode 330. The interlayer insulating film 332 may be formed of an inorganic insulating material such as silicon oxide or silicon nitride, or an organic insulating material such as benzocyclobutene or photo-acryl.

The interlayer insulating film 332 has first and second contact holes 334 and 336 exposing both sides of the semiconductor layer 322. The first and second contact holes 334 and 336 are located on both sides of the gate electrode 330 and are spaced apart from the gate electrode 330 .

Here, the first and second contact holes 334 and 336 are also formed within the gate insulating film 324. Alternatively, when the gate insulating film 324 is patterned to have the same shape as the gate electrode 330, the first and second contact holes 334 and 336 may be formed only within the interlayer insulating film 332.

A source electrode 340 and a drain electrode 342 made of a conductive material such as metal are formed on the interlayer insulating film 332.

The source electrode 340 and the drain electrode 342 are positioned spaced apart from each other around the gate electrode 330, and are provided on both sides of the semiconductor layer 322 through the first and second contact holes 334 and 336, respectively. come into contact with

The semiconductor layer 322, the gate electrode 330, the source electrode 340, and the drain electrode 342 form the thin film transistor (Tr), and the thin film transistor (Tr) is a driving element. ) functions as

The thin film transistor (Tr) has a coplanar structure in which the gate electrode 330, the source electrode 342, and the drain electrode 344 are located on the semiconductor layer 320.

In contrast, the thin film transistor (Tr) may have an inverted staggered structure in which the gate electrode is located at the bottom of the semiconductor layer and the source electrode and drain electrode are located at the top of the semiconductor layer. In this case, the semiconductor layer may be made of amorphous silicon.

Although not shown, gate wires and data wires intersect each other to define a pixel area, and a switching element connected to the gate wire and data wire is further formed. The switching element is connected to a thin film transistor (Tr), which is a driving element.

In addition, a power wire is formed parallel to and spaced apart from the data wire or the data wire, and a storage capacitor is further provided to keep the voltage of the gate electrode of the thin film transistor (Tr), which is a driving element, constant during one frame. It can be configured.

A protective layer 350 having a drain contact hole 352 exposing the drain electrode 342 of the thin film transistor (Tr) is formed to cover the thin film transistor (Tr).

On the protective layer 350, a first electrode 360 connected to the drain electrode 342 of the thin film transistor (Tr) through the drain contact hole 352 is formed separately for each pixel area. The first electrode 360 may be an anode and may be made of a conductive material with a relatively high work function value. For example, the first electrode 360 may be made of a transparent conductive material such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO). .

Additionally, a bank layer 366 is formed on the protective layer 350 to cover the edge of the first electrode 360. The bank layer 366 exposes the center of the first electrode 360 corresponding to the pixel area.

A light emitting layer 362 is formed on the first electrode 360. The light-emitting layer 362 may have a single-layer structure of an emitting material layer made of a light-emitting material. In addition, in order to increase luminous efficiency, the light-emitting layer 362 includes a hole injection layer, a hole transport layer, a light-emitting material layer, and an electron transport layer ( It may have a multi-layer structure of an electron transporting layer and an electron injection layer.

The light-emitting material layer may include an inorganic light-emitting material such as quantum dots, or an organic light-emitting material.

A second electrode 364 is formed on the plastic substrate 310 on which the light emitting layer 362 is formed. The second electrode 364 is located in front of the display area and is made of a conductive material with a relatively low work function value and can be used as a cathode. For example, the second electrode 364 may be made of any one of aluminum (Al), magnesium (Mg), and aluminum-magnesium alloy (AlMg).

The first electrode 360, the light emitting layer 362, and the second electrode 364 form a light emitting diode (D).

An encapsulation film 370 may be formed on the second electrode 364 to prevent external moisture from penetrating into the light emitting diode (D). The encapsulation film 370 may have a stacked structure of a first inorganic insulating layer 372, an organic insulating layer 374, and a second inorganic insulating layer 374, but is not limited to this.

Additionally, a polarizing plate (not shown) may be attached to the encapsulation film 370 to reduce external light reflection. For example, the polarizer may be a circular polarizer.

In such a display device 300, the plastic substrate 310 is a plastic substrate (100 in FIG. 1) according to the first embodiment of the present invention or a plastic substrate (200 in FIG. 3) according to the second embodiment of the present invention. )am.

For example, the plastic substrate 310 may be composed of a first base (210 in FIG. 3) with pores (212 in FIG. 3) therein and a second base (220 in FIG. 3) without pores. .

The light emitting diode display device 300 of the present invention has bottom emission in which light from the light emitting layer 362 passes through the first electrode 360 and the plastic substrate 310 and an image is displayed on the plastic substrate 310. ) method, and since the plastic substrate 310 has excellent optical properties, display quality does not deteriorate.

Additionally, since the plastic substrate 310 contains inorganic particles during the manufacturing process and has a low coefficient of thermal expansion, thermal deformation problems such as bending of the plastic substrate 310 do not occur during the high-temperature manufacturing process.

Additionally, the rigidity of the plastic substrate 310 increases and optical properties are further improved by the second base 220 of the plastic substrate 310.

Figure 6 is a schematic cross-sectional view of a display device according to a fourth embodiment of the present invention.

Meanwhile, as shown in FIG. 6, the display device 400 is interposed between first and second plastic substrates 410 and 450 facing each other, and the first and second plastic substrates 410 and 450. It includes a liquid crystal layer 460 containing liquid crystal molecules 462. That is, the display device 400 according to the fourth embodiment of the present invention is a liquid crystal display device.

A first buffer layer 420 is formed on the first plastic substrate 410, and a thin film transistor (Tr) is formed on the first buffer layer 420. The first buffer layer 420 may be omitted.

A gate electrode 422 is formed on the first buffer layer 420, and a gate insulating film 424 is formed covering the gate electrode 422. Additionally, a gate wire (not shown) connected to the gate electrode 422 is formed on the buffer layer 420.

A semiconductor layer 426 is formed on the gate insulating film 424 to correspond to the gate electrode 422. The semiconductor layer 426 may be made of an oxide semiconductor material. Meanwhile, the semiconductor layer 426 may include an active layer made of amorphous silicon and an ohmic contact layer made of impurity amorphous silicon.

A source electrode 430 and a drain electrode 432 are formed on the semiconductor layer 426 and are spaced apart from each other. Additionally, a data wire (not shown) connected to the source electrode 430 is formed to intersect the gate wire to define a pixel area.

The gate electrode 422, the semiconductor layer 426, the source electrode 430, and the drain electrode 432 constitute a thin film transistor (Tr).

A protective layer 434 having a drain contact hole 436 exposing the drain electrode 432 is formed on the thin film transistor (Tr).

On the protective layer 434, a pixel electrode 440 is connected to the drain electrode 432 through the drain contact hole 436, and a common electrode 442 is alternately arranged with the pixel electrode 440. is formed

A second buffer layer 452 is formed on the second plastic substrate 450, and a black matrix (black matrix) that covers non-display areas such as the thin film transistor (Tr), the gate wire, and the data wire is formed on the second buffer layer 452. 454) is formed. Additionally, a color filter layer 456 is formed corresponding to the pixel area. The second buffer layer 452 and the black matrix 454 may be omitted.

The first and second plastic substrates 410 and 450 are bonded with a liquid crystal layer 460 interposed therebetween, and the liquid crystal layer ( 460) liquid crystal molecules are driven. Meanwhile, the common electrode 442 may be formed on the second plastic substrate 450.

Although not shown, an alignment film may be formed on the top of each of the first and second plastic substrates 410 and 450 in contact with the liquid crystal layer 460, and the first and second plastic substrates 410 and 450, respectively. A polarizing plate having transmission axes perpendicular to each other may be attached to the outside of . Additionally, a backlight unit including a light source is disposed below the first plastic substrate 410.

In such a display device 400, at least one of the first and second plastic substrates 410 and 450 is a plastic substrate (100 in FIG. 1) according to the first embodiment of the present invention or the second embodiment of the present invention. This is a plastic substrate (200 in FIG. 3) according to an example.

For example, each of the first and second plastic substrates 410 and 450 includes a first base (210 in FIG. 3) with pores (212 in FIG. 3) therein and a second base without pores (212 in FIG. 3). It can be composed of 220).

In the liquid crystal display device 400 of the present invention, light from a backlight unit (not shown) passes through the first plastic substrate 410, the liquid crystal layer 460, and the second plastic substrate 450, and the light passes through the second plastic substrate 450. The image is displayed from the (450) side.

At this time, because the first and second plastic substrates 410 and 450 have excellent optical properties, display quality does not deteriorate.

In addition, because the first and second plastic substrates 410 and 450 contain inorganic particles during the manufacturing process and have a low coefficient of thermal expansion, the first and second plastic substrates 410 and 450 are subject to warping and bending during the high temperature manufacturing process. The same thermal deformation problem does not occur.

In addition, the rigidity of the first and second plastic substrates 410 and 450 increases and optical properties are further improved by the second base 220 of each of the first and second plastic substrates 410 and 450.

Figure 7 is a schematic cross-sectional view of a display device according to a fifth embodiment of the present invention.

Meanwhile, as shown in FIG. 7 , the display device 500 includes a first substrate 510, a display element 520, a touch element 530, and a plastic substrate 560.

For example, the first substrate 510 may be a glass substrate or a plastic substrate. When the display device 500 according to the fifth embodiment of the present invention is a light emitting diode display device, the optical characteristics of the first substrate 510 are not an important factor because the image is displayed on the plastic substrate 560 side. Therefore, when the first substrate 510 is a plastic substrate, a plastic substrate with excellent thermal properties can be used without considering optical properties.

The touch element 530 includes a touch electrode or a touch wire, and is attached to the top of the display element 520.

The touch element 530 is formed on the plastic substrate 560 and attached to the display element 520.

At this time, since the touch element 530 is formed while the plastic substrate 560 is attached to the carrier substrate and the image is displayed on the plastic substrate 560, the plastic substrate 560 has thermal properties and optical properties. All characteristics must be considered.

Accordingly, the plastic substrate 560 according to the first embodiment of the present invention (100 in FIG. 1) or the plastic substrate (200 in FIG. 3) according to the second embodiment of the present invention is used.

For example, the plastic substrate 560 is composed of a first base 550 with pores 552 therein and a second base 540 without pores, and the A touch element 530 is formed.

As described above, in the display device 500 of the present invention, light from the display element 520 passes through the plastic substrate 560 and an image is displayed on the plastic substrate 560, and the plastic substrate 560 Because it has excellent optical properties, display quality does not deteriorate.

Additionally, since the plastic substrate 560 contains inorganic particles during the manufacturing process and has a low coefficient of thermal expansion, thermal deformation problems such as bending of the plastic substrate 560 do not occur during the high-temperature manufacturing process.

Additionally, the rigidity of the plastic substrate 560 increases and optical properties are further improved by the second base 540 of the plastic substrate 560.

Although the present invention has been described above with reference to preferred embodiments, those skilled in the art may modify the present invention in various ways without departing from the technical spirit and scope of the present invention as set forth in the claims below. and that it can be changed.

100, 200, 310, 410, 450, 560: Plastic substrate
110, 210, 220, 540, 550: base 112, 212, 552: pore
114, 214: Inorganic particles 300, 400, 500: Display device

Claims (12)

A first base including a plurality of pores therein;
a second base located on one side of the first base and having no pores;
A third base containing inorganic particles and located between the first and second bases
A plastic substrate containing a.

delete According to claim 1,
The first and second bases are plastic substrates made of the same polyimide.
According to claim 1,
The first base has a first thickness, and the second base has a second thickness smaller than the first thickness.

delete According to claim 1,
The third base is a plastic substrate having a thickness smaller than that of the first base.
A plastic substrate according to any one of claims 1, 3, 4, and 6;
Light emitting diode located on the plastic substrate
A display device including a.
first and second substrates facing each other;
a pixel electrode located on the first substrate;
a common electrode located on one of the first and second substrates;
It includes a liquid crystal layer located between the first and second substrates,
A display device wherein at least one of the first and second substrates is the plastic substrate of any one of claims 1, 3, 4, and 6.
a first substrate;
a display element located on the first substrate;
a touch element located on the display element;
A display device including the plastic substrate of any one of claims 1, 3, 4, and 6 located on the touch element.
Attaching a base having inorganic particles to a carrier substrate;
forming a display element on the base;
separating the base on which the display element is formed and the carrier substrate;
Removing the inorganic particles from the separated base
A method of manufacturing a display device comprising:
According to claim 10,
The method of manufacturing a display device, wherein the base includes a first base containing the inorganic particles and a second base without the inorganic particles, and the first base is in contact with the carrier substrate. According to claim 1,
Each of the first to third bases is a plastic substrate made of polyimide.

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