Method of manufacturing flexible substrate and method of manufacturing display device using the same

A sacrificial layer is formed on a support substrate and a flexible substrate is formed on the sacrificial layer. Pixels are then formed on the flexible substrate. The sacrificial layer is heated by microwave energy, and a gas is discharged from the sacrificial layer. The flexible substrate, including the pixels formed thereon, is separated from the support substrate including the sacrificial layer formed thereon using the gas.

CROSS-REFERENCE TO RELATED APPLICATION

This U.S. non-provisional patent application claims priority from and the benefit of Korean Patent Application No. 10-2013-0167183, filed on Dec. 30, 2013, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND

Exemplary embodiments of the present invention relate to a method of manufacturing a flexible substrate, and a method of manufacturing a display device using the same. More particularly, exemplary embodiments of the present invention relate to a method of manufacturing a flexible substrate on a support substrate, and a method of manufacturing a display device using the same.

2. Discussion of the Background

In recent years, a display device including a flexible substrate has been developed. The display device having the flexible substrate is curved in response to a user's demand and, thus, the display device provides improved convenience for a user in during moving or handling of the display device. A plastic substrate, e.g., a polyimide substrate having superior thermal resistance and strength, and a metal substrate are widely used as the flexible substrate.

When the display device is manufactured using the flexible substrate, a support substrate, such as a glass substrate, may be used to form the flexible substrate in order to secure a surface flatness of the flexible substrate. For instance, the flexible substrate is disposed on the support substrate, and thin film forming processes are performed on the flexible substrate to form pixels on the flexible substrate. Then, the flexible substrate on which the pixels are formed is separated from the support substrate. However, the flexible substrate may become strongly attached to the support substrate while the pixels are formed. As result, separating the flexible substrate from the support substrate may be difficult.

SUMMARY

Exemplary embodiments of the present invention provide a method of manufacturing a flexible substrate.

Exemplary embodiments of the present invention provide a method of manufacturing a display device using the manufacturing method of the flexible substrate.

An exemplary embodiment of the present invention discloses a method of manufacturing a flexible substrate, including forming a sacrificial layer on a support substrate, and then forming a flexible substrate on the sacrificial layer. Then, the sacrificial layer is heated using microwave energy to generate a gas from the sacrificial layer. The flexible substrate is then separated from the support substrate, on which the sacrificial layer is formed, using the gas.

An exemplary embodiment of the present invention also discloses a method of manufacturing a flexible substrate, including forming a sacrificial layer on a support substrate, and then forming a flexible substrate on the sacrificial layer. Then, pixels are formed on the flexible substrate, and the sacrificial layer is heated using microwave energy to generate a gas from the sacrificial layer. The flexible substrate, including the pixels formed thereon, is then separated from the support substrate, on which the sacrificial layer is formed, using the gas.

The support substrate is a glass substrate, the flexible substrate is a polyimide substrate, and the sacrificial layer comprises a silicon carbide bonded with hydrogen.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The invention now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure is thorough, and will fully convey the scope of the invention to those skilled in the art. In the drawings, like reference numerals denote like elements, and the sizes and thicknesses of layers and regions may be exaggerated for clarity.

It will be understood that when an element or layer is referred to as being “on”, “connected to”, or “coupled to” another element or layer, it can be directly on, connected to, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to”, or “directly coupled to” another element or layer, there are no intervening elements or layers present. It will be understood that for the purposes of this disclosure, “at least one of X, Y, and Z” can be construed as X only, Y only, Z only, or any combination of two or more items X, Y, and Z (e.g., XYZ, XYY, YZ, ZZ). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Referring toFIG. 1, a sacrificial layer containing silicon carbide (SiC) bonded with hydrogen (hydrogenated silicon carbide) is formed on a support substrate (S10). The support substrate may be, for example, a glass substrate. In addition, the sacrificial layer may be formed by a chemical vapor deposition method using a source gas containing silane (SiH4) and methane (CH4).

A flexible substrate is then formed on the sacrificial layer (S20). The flexible substrate may be, for example, a polyimide substrate. The polyimide substrate is formed by providing polyamic acid (PAA) on the sacrificial layer as a precursor of polyimide, and then curing the polyamic acid.

A pixel part including pixels is then formed on the flexible substrate formed on the support substrate (S30). When the display device is an organic electroluminescent display device, each of the pixels includes an anode, a cathode, and an organic light emitting layer interposed between the anode and the cathode. On the other hand, when the display device is a liquid crystal display device, each of the pixels includes a pixel electrode, an opposite electrode, and a liquid crystal layer interposed between the pixel electrode and the opposite substrate.

Then, the sacrificial layer is heated using microwave to vaporize the hydrogen in the sacrificial layer (S40). The microwaves generally have a frequency of about 8 GHz to about 16 GHz, and the sacrificial layer is heated at a temperature of about 400° C. to about 500° C. by controlling a time during which the microwave energy is radiated onto the sacrificial layer.

When the sacrificial layer is heated at a temperature of about 400° C. to about 500° C., the hydrogen contained in the sacrificial layer is vaporized, and a gas is discharged from the sacrificial layer. More specifically, when the sacrificial layer is heated, a dehydrogenation occurs in the sacrificial layer, and the hydrogen is stripped from the silicon carbide contained in the sacrificial layer and released as a vapor. Therefore, the gas is discharged from the sacrificial layer.

Then, the flexible substrate, including the pixel part formed thereon, is separated from the support substrate using the gas (S50). In more detail, a bonding strength between the flexible substrate and the sacrificial layer is reduced as a result of the gas discharged from the sacrificial layer. Thus, the flexible substrate, including the pixel part formed thereon, may be easily separated from the support substrate, resulting in the manufacture of the display device including the flexible substrate and the pixel part.

FIGS. 2A to 2Gare views showing the manufacturing method of the display device.

Referring toFIG. 2A, a support substrate10is prepared, in which a cell area CA and an edge area EA disposed outside the cell area CA are defined. The support substrate10may be, for example, a glass substrate or a rigid substrate, e.g., a wafer.

A preliminary sacrificial layer20is formed on the support substrate10to correspond to the cell area CA and the edge area EA.

The preliminary sacrificial layer20may be formed of an inorganic material that absorbs the microwave energy. In an exemplary embodiment, the hydrogenated silicon carbide of the preliminary sacrificial layer20is heated by absorbing the microwave energy.

In the present exemplary embodiment, the preliminary sacrificial layer20is formed by the chemical vapor deposition (CVD) method. When the preliminary sacrificial layer20is formed of hydrogenated silicon carbide, the source gas28used in the chemical vapor deposition may include silane (SiH4) and methane (CH4).

In an exemplary embodiment, a weight percent (wt %) of the hydrogen in the preliminary sacrificial layer20is in a range from about 1 wt % to about 50 wt %. When the weight percent of the hydrogen in the preliminary sacrificial layer20is less than about 1 wt %, an amount of the gas GS (refer toFIG. 2F) discharged from the preliminary sacrificial layer20may be reduced. In addition, when the weight percent of the hydrogen in the preliminary sacrificial layer20exceeds about 50 wt %, a weight percent of the silicon carbide contained in the preliminary sacrificial layer20becomes smaller. Accordingly, these situations result in a deterioration in the absorbance of the sacrificial layer with respect to the energy of the microwave MW (refer toFIG. 2F), and thus, a time required to heat the sacrificial layer is increased.

Referring toFIGS. 2B and 2C, a portion of the preliminary sacrificial layer20(refer toFIG. 2A), which corresponds to the edge area EA, is removed to form the sacrificial layer25. Because the preliminary sacrificial layer20is patterned to form the sacrificial layer25, the sacrificial layer25includes the same material as that of the preliminary sacrificial layer.

In an exemplary embodiment, the sacrificial layer25may have, for example, a thickness of about 1 micrometer to about 30 micrometers. The sacrificial layer25is used to lower the bonding strength between the flexible substrate35(refer toFIG. 2G) and the support substrate10(refer toFIG. 2G), and thus, the thickness of the sacrificial layer25may be increased as thickness, size, or weight of the flexible substrate is increased.

Then, a source solution SL is provided to the cell area CA and the edge area EA using a spray unit DP. As a result, a first preliminary substrate30is formed on the support substrate30and covers the sacrificial layer25.

In an exemplary embodiment, the source solution SL may include polyamic acid (PAA) and a solvent. The source solution SL may be provided to the support substrate10using a slit coating device or a spin coating device, which includes the spray unit DP.

Heat HT is provided to the first preliminary substrate30to remove the solvent from the preliminary substrate30. Thus, the first preliminary substrate30is cured to form a second preliminary substrate31.

Referring toFIG. 2D, a pixel part PXL is formed on the second preliminary substrate31, and a sealing layer40is formed to cover the pixel part PXL. In more detail, the pixel part PXL is formed on the second preliminary substrate31to correspond to the cell area CA. The sealing layer40is formed on the pixel part PXL and the second preliminary substrate31to correspond to the cell area CA and the edge area EA. That is, because the sealing layer40covers the pixel part PXL in the cell area CA and covers a side portion of the pixel PXL in the edge area EA, the pixel part PXL is sealed by the sealing layer40.

In an exemplary embodiment, the pixel part PXL includes pixels, where each of the pixels includes the anode, the cathode, and the organic light emitting layer interposed between the anode and the cathode (not shown). According to another exemplary embodiment, each of the pixels may include the pixel electrode, the opposite electrode, and the liquid crystal layer interposed between the pixel electrode and the opposite electrode (all not shown). In this case, the opposite substrate may be provided instead of the sealing layer40, and the opposite substrate may be coupled to the second preliminary substrate31by a sealant (not shown) formed in the edge area EA.

Referring toFIGS. 2D and 2E, a portion of the second preliminary substrate31, which corresponds to the edge area EA, is removed to form the flexible substrate35. A portion of the sealing layer40corresponding to the edge area EA is removed to form a sealing part45.

Because the side portion of the sacrificial layer25may be exposed in the edge area EA before the sacrificial layer25is heated using the microwave, the gas GS (refer toFIG. 2F) generated while the sacrificial layer25is heated may be discharged to the outside of the sacrificial layer25.

Referring toFIGS. 2F and 2G, the sacrificial layer25is heated by the microwave energy MW. When the support substrate10is a glass substrate, the flexible substrate35may be a polyimide substrate, and the sacrificial layer25may include hydrogenated silicon, such that an amount of microwave energy MW, which is absorbed by the sacrificial layer25, is greater than an amount of microwave energy MW, which is absorbed by each of the support substrate10and the flexible substrate35. Accordingly, during microwave energy MW upon the sacrificial layer25, the sacrificial layer25may be selectively heated from among the support substrate10, the flexible substrate35, and the sacrificial layer25.

In an exemplary embodiment, the radiation time of the microwave energy MW onto the sacrificial layer25may be controlled such that the sacrificial layer25is heated at a temperature of about 400° C. to about 500° C.

When the sacrificial layer25is heated by the microwave energy MW, dehydrogenation occurs in the sacrificial layer25and vaporized hydrogen is released as the gas GS. Therefore, the gas GS is discharged from the sacrificial layer25. Thus, the bonding strength between the flexible substrate35and the sacrificial layer25is reduced by the gas GS, so that the flexible substrate25including the pixel part PXL formed thereon is easily separated from the support substrate10, thereby completing the display device100including the flexible substrate35and the pixel part PXL.

In addition, a portion of the gas GS is discharged to the outside since the side portion of the sacrificial layer25is exposed to the outside while the sacrificial layer25is heated. Accordingly, the gas GS may be prevented from being entrapped between the flexible substrate35and the sacrificial layer25, and pressurization of the pixel part PXL by the gas GS may be prevented.

FIG. 3is a flowchart showing a manufacturing method of a flexible substrate according to another exemplary embodiment of the present invention.

Referring toFIG. 3, a sacrificial layer containing hydrogenated silicon carbide (SiC) is formed on a support substrate (S110).

In the present exemplary embodiment, the support substrate may be, for example, a glass substrate. In addition, the sacrificial layer may be formed by a chemical vapor deposition method using a source gas containing silane (SiH4) and methane (CH4).

Then, a flexible substrate is formed on the sacrificial layer (S120). In the present exemplary embodiment, the flexible substrate may be, for example, a polyimide substrate. The polyimide substrate may be formed by providing polyamic acid (PAA) on the sacrificial layer as a precursor of polyimide, and curing the polyamic acid.

Then, the sacrificial layer is heated using microwave energy to vaporize the hydrogen in the sacrificial layer (S130). The microwaves have a frequency of about 8 GHz to about 16 GHz, and the sacrificial layer is heated at a temperature of about 400° C. to about 500° C. by controlling radiation time of the microwave energy upon the sacrificial layer.

When the sacrificial layer is heated at the temperature of about 400° C. to about 500° C., the hydrogen contained in the sacrificial layer is vaporized, and a gas is discharged from the sacrificial layer. In more detail, when the sacrificial layer is heated, a dehydrogenation occurs in the sacrificial layer and the hydrogen stripped from the silicon carbide contained in the sacrificial layer is vaporized. Therefore, the gas is discharged from the sacrificial layer.

Then, the flexible substrate is separated from the support substrate using the gas (S140). In more detail, a bonding strength between the flexible substrate and the sacrificial layer is reduced as a result of the gas discharged from the sacrificial layer, and thus, the flexible substrate may be easily separated from the support substrate. As a result, the flexible substrate may be manufactured.

According to the above, the sacrificial layer is formed between the support substrate and the flexible substrate, and the flexible substrate is easily separated from the support substrate using the gas discharged from the sacrificial layer heated by the microwave. Therefore, a process of radiating a laser beam to an interface between the flexible substrate and the sacrificial layer may be omitted and, thus, the cost and time required to manufacture the display device may be reduced.

In addition, the sacrificial layer includes silicon carbide that absorbs the energy of the microwave. Thus, although the microwave is radiated to the structure in which the support substrate, the sacrificial layer, and the flexible substrate are sequentially stacked one on another, the sacrificial layer may be selectively heated by the microwave.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the present invention as defined by the following claims. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.