阅读说明：本技术 柔性oled装置、其制造方法以及支承基板
(Flexible OLED device, manufacturing method thereof and supporting substrate
) 是由 岸本克彦
西冈幸也 于 2018-02-27 设计创作，主要内容包括：根据本公开的柔性OLED装置的制造方法,准备层叠结构体(100),该层叠结构体(100)具备：基底(10)、包含TFT层以及OLED层在内的功能层区域(20)、位于基底与功能层区域之间且支承功能层区域的柔性膜(30)、位于柔性膜与基底之间且固定于基底的释放层(12)。用透过基底的剥离光(216)照射释放层以将柔性膜从释放层剥离。释放层由氮化钽的多晶体制成。(According to the method for manufacturing a flexible OLED device of the present disclosure, a laminated structure (100) is prepared, and the laminated structure (100) includes: the thin film transistor comprises a substrate (10), a functional layer region (20) including a TFT layer and an OLED layer, a flexible film (30) located between the substrate and the functional layer region and supporting the functional layer region, and a release layer (12) located between the flexible film and the substrate and fixed on the substrate. The release layer is irradiated with a peeling light (216) transmitted through the substrate to peel the flexible film from the release layer. The release layer is made of polycrystalline body of tantalum nitride.)
1. A method for manufacturing a flexible OLED device, comprising the steps of:
a step of preparing a laminated structure, wherein the laminated structure comprises: a substrate; a functional layer region including a TFT layer and an OLED layer; a flexible membrane positioned between the substrate and the functional layer area and supporting the functional layer area; and a release layer positioned between the flexible film and the substrate and secured to the substrate; and
a step of irradiating the release layer with an ultraviolet laser light transmitted through the substrate to peel the flexible film from the release layer,
the release layer is made of polycrystalline body of tantalum nitride.
2. The manufacturing method according to claim 1,
the tantalum nitride includes nitrogen in a molar ratio higher than that of tantalum included in the tantalum nitride.
3. The manufacturing method according to claim 1 or 2,
the surface of the release layer has a relief pattern,
the back surface of the flexible film has a pattern to which the concave-convex pattern of the surface of the release layer is transferred.
4. The manufacturing method according to any one of claims 1 to 3,
the release layer has a thickness of 50nm or more and 500nm or less.
5. The manufacturing method according to any one of claims 1 to 4,
the wavelength of the ultraviolet laser is 300nm to 360 nm.
6. The manufacturing method according to any one of claims 1 to 5,
the thickness of the flexible film is 5 [ mu ] m or more and 20 [ mu ] m or less.
7. The manufacturing method according to any one of claims 1 to 6,
the step of preparing the laminated structure includes the steps of:
forming a polycrystal of the tantalum nitride on the substrate by sputtering a tantalum target in a nitrogen-containing gas atmosphere; and
and forming the flexible film on the polycrystalline body of tantalum nitride.
8. A flexible OLED device, comprising:
a functional layer region including a TFT layer and an OLED layer; and
a flexible membrane supporting the functional layer region,
the back surface of the flexible film has a relief pattern.
9. The flexible OLED device of claim 8,
the unevenness of the unevenness pattern has a shape and a size that diffuse and reflect visible light.
10. Flexible OLED device according to claim 8 or 9,
the thickness of the flexible film is 5 [ mu ] m or more and 20 [ mu ] m or less,
the flexible OLED device also includes a support film bonded to the back side of the flexible film.
11. A support substrate for a flexible OLED device, the support substrate comprising:
a release layer made of a polycrystalline body of tantalum nitride; and
a substrate made of a material that transmits ultraviolet rays and supporting the release layer.
12. The support substrate of claim 11,
the tantalum nitride includes nitrogen in a molar ratio higher than that of tantalum included in the tantalum nitride.
13. The support substrate according to claim 11 or 12,
the surface of the release layer has a relief pattern.
14. The support substrate according to any one of claims 11 to 13, further comprising:
a flexible film covering the release layer.
15. The support substrate of claim 14,
the back surface of the flexible film has irregularities that match the irregularity pattern provided on the surface of the release layer, and the irregularities have a shape and a size that allow visible light to be diffusely reflected.
Technical Field
The present disclosure relates to flexible OLED devices, methods of manufacturing the same, and support substrates.
Background
A typical example of the flexible display includes elements such as a Film formed of a synthetic resin such as polyimide (hereinafter referred to as a "resin Film"), a TFT (Thin Film Transistor) supported by the resin Film, and an OLED (Organic light emitting Diode). The resin film functions as a flexible substrate. Since the organic semiconductor layer constituting the OLED is easily deteriorated by water vapor, the flexible display is encapsulated by a gas barrier film (encapsulation film).
A flexible display can be manufactured using a glass substrate having a resin film formed on an upper surface thereof. The glass substrate functions as a support (carrier) for maintaining the shape of the resin film in a planar shape during the manufacturing process. By forming elements such as TFTs and OLED elements, and a gas barrier film on a resin film, the structure of a flexible OLED device can be realized while being supported by a glass substrate. The flexible OLED device was then peeled off the glass substrate for flexibility. The portion where elements such as TFTs and OLEDs are arranged may be referred to as a "functional layer region" as a whole.
Patent document 1 discloses a method of irradiating an interface between a flexible substrate and a glass substrate with ultraviolet laser light (peeling light) to peel the flexible substrate on which an OLED device is placed from the glass substrate. In the method disclosed in patent document 1, an amorphous silicon layer is disposed between a flexible substrate and a glass base. Irradiation with ultraviolet laser light causes hydrogen to be generated from the amorphous silicon layer, and the flexible substrate is peeled from the glass substrate.
Disclosure of Invention
Technical problem to be solved by the invention
Since the conventional resin film absorbs ultraviolet rays, the influence of peeling light irradiation on the TFT element and the OLED element has not been particularly studied. However, according to the studies of the present inventors, it was found that the ultraviolet laser used in the lift-off process may deteriorate the TFT element and the OLED element.
The present disclosure provides a flexible OLED device, a method of manufacturing the same, and a support substrate capable of solving the above technical problems.
Means for solving the problems
In an exemplary embodiment, the method for manufacturing a flexible OLED device of the present disclosure includes the steps of: a step of preparing a laminated structure, wherein the laminated structure comprises: a substrate; a functional layer region including a TFT layer and an OLED layer; a flexible membrane positioned between the substrate and the functional layer area and supporting the functional layer area; and a release layer positioned between the flexible film and the substrate and secured to the substrate; and a step of irradiating the release layer with ultraviolet laser light transmitted through the substrate to peel the flexible film from the release layer. The release layer is made of polycrystalline body of tantalum nitride.
In one embodiment, the tantalum nitride comprises a higher molar ratio of nitrogen than the tantalum.
In one embodiment, a surface of the release layer has a concave-convex pattern, and a back surface of the flexible film has a pattern to which the concave-convex pattern of the surface of the release layer is transferred.
In one embodiment, the release layer has a thickness of 50nm or more and 500nm or less.
In one embodiment, the thickness of the flexible film is 5 μm or more and 20 μm or less.
In one embodiment, the wavelength of the ultraviolet laser is 300nm or more and 360nm or less.
In one embodiment, the step of preparing the laminated structure includes the steps of: forming a polycrystal of the tantalum nitride on the substrate by sputtering a tantalum target in a nitrogen-containing gas atmosphere; and forming the flexible film on the polycrystalline body of tantalum nitride.
In an example embodiment, a flexible OLED device of the present disclosure includes: a functional layer region including a TFT layer and an OLED layer; and a flexible film supporting the functional layer region, a back surface of the flexible film having a concave-convex pattern.
In one embodiment, the irregularities of the irregularity pattern have a shape and a size that diffuse and reflect visible light.
In one embodiment, the flexible film has a thickness of 5 μm or more and 20 μm or less, and the flexible OLED device further includes a support film adhered to the rear surface of the flexible film.
An exemplary embodiment of the support substrate in the present disclosure is a support substrate of a flexible OLED device, including: a release layer made of a polycrystalline body of tantalum nitride; and a substrate made of a material that transmits ultraviolet rays and supporting the release layer.
In one embodiment, the tantalum nitride comprises a higher molar ratio of nitrogen than the tantalum.
In one embodiment, the surface of the release layer has a relief pattern.
In one embodiment, the method further comprises: a flexible film covering the release layer.
In one embodiment, the back surface of the flexible film has irregularities matching the irregularity pattern of the front surface of the release layer, and the irregularities have a shape and a size that diffuse and reflect visible light.
Effects of the invention
According to embodiments of the present invention, a new flexible OLED device, a method of manufacturing the same, and a support substrate solving the above-mentioned problems are provided.
Drawings
Fig. 1A is a plan view showing a configuration example of a laminated structure body used in a method of manufacturing a flexible OLED device according to the present disclosure.
Fig. 1B is a sectional view of the laminated structure shown in fig. 1A taken along line B-B.
Fig. 2A is a process cross-sectional view illustrating a method of manufacturing a support substrate in an embodiment of the present disclosure.
Fig. 2B is a process cross-sectional view illustrating a method of manufacturing a support substrate in an embodiment of the present disclosure.
Fig. 3A is a process sectional view illustrating a method of manufacturing a flexible OLED device in an embodiment of the present disclosure.
Fig. 3B is a process sectional view illustrating a method of manufacturing a flexible OLED device in an embodiment of the present disclosure.
Fig. 3C is a process sectional view illustrating a method of manufacturing a flexible OLED device in an embodiment of the present disclosure.
Fig. 3D is a process sectional view illustrating a method of manufacturing a flexible OLED device in an embodiment of the present disclosure.
Fig. 4 is an equivalent circuit diagram of one sub-pixel in a flexible OLED device.
Fig. 5 is a perspective view of the laminated structure at a stage in the manufacturing process.
Fig. 6A is a cross-sectional view schematically showing a division position of the laminated structure.
Fig. 6B is a plan view schematically showing a division position of the laminated structure.
Fig. 7A is a diagram schematically showing a state of the stage before supporting the laminated structure.
Fig. 7B is a diagram schematically showing a state in which the laminated structure is supported by the stage.
Fig. 7C is a view schematically showing a state in which the interface between the substrate of the laminated structure and the resin film is irradiated with laser light (peeling light) formed in a straight line.
Fig. 8A is a perspective view schematically showing a case where the laminated structure is irradiated with a linear beam emitted from a beam light source of the peeling device.
Fig. 8B is a diagram schematically showing the position of the stage at the start of irradiation with the stripping light.
Fig. 8C is a diagram schematically showing the position of the stage at the end of irradiation of the stripping light.
Fig. 9A is a cross-sectional view schematically showing a state after irradiation of the peeling light before the laminated structure is separated into the first portion and the second portion.
Fig. 9B is a sectional view schematically showing a state where the stacked structural body has been separated into the first portion and the second portion.
Fig. 10 is a cross-sectional view schematically illustrating the irregularities in the rear surface of the flexible substrate of the OLED device 1000.
Detailed Description
Embodiments of a method of manufacturing a flexible OLED device and a manufacturing apparatus according to the present disclosure are explained with reference to the accompanying drawings. In the following description, unnecessary detailed description may be omitted. For example, detailed descriptions of known matters and overlapping descriptions of substantially the same configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. The figures and the following description are provided by the inventors for a full understanding of the disclosure by those skilled in the art. These are not intended to limit the subject matter recited in the claims.
< laminated Structure >
Refer to fig. 1A and 1B. In the method of manufacturing the flexible OLED device in this embodiment, first, the stacked structure 100 shown in fig. 1A and 1B is prepared. Fig. 1A is a plan view of the stacked structural body 100, and fig. 1B is a sectional view of the stacked structural body 100 shown in fig. 1A taken along line B-B. For reference, an XYZ coordinate system having X, Y, and Z axes orthogonal to each other is shown in fig. 1A and 1B.
The laminated structure 100 of the present embodiment includes: substrate (mother substrate or carrier)
10. A functional layer region 20 including a TFT layer 20A and an OLED layer 20B, a flexible film 30 positioned between the substrate 10 and the functional layer region 20 and supporting the functional layer region 20, and a release layer 12 positioned between the flexible film 30 and the substrate 10 and fixed to the substrate 10. The release layer 12 is made of polycrystalline body of tantalum nitride. Preferably, the tantalum nitride contains nitrogen in a higher molar ratio than the tantalum.
The laminated structure 100 further includes a protective sheet 50 and a gas barrier film 40 between the plurality of functional layer regions 20 and the protective sheet 50, the protective sheet 50 covering the plurality of functional layer regions 20, and the gas barrier film 40 covering the entire functional layer region 20. The laminated structure 100 may have another layer such as a buffer layer (not shown).
A typical example of the substrate 10 is a glass substrate having rigidity. A typical example of the flexible film 30 is a synthetic resin film having flexibility. Hereinafter, the "flexible film" is simply referred to as "resin film". The structure comprising the release layer 12 and the substrate 10 supporting the release layer 12 as a whole is referred to as the "support substrate" of the flexible OLED device. The support substrate may also further include other films (e.g., flexible films) covering the release layer 12.
The first surface 100a of the laminated structure 100 in the present embodiment is defined by the substrate 10, and the second surface 100b is defined by the protective sheet 50. The substrate 10 and the protective sheet 50 are components that are temporarily used in the manufacturing process, not the elements that constitute the final flexible OLED device.
The illustrated resin film 30 includes a plurality of flexible substrate regions 30d that support the plurality of functional layer regions 20, respectively, and an intermediate region 30i that surrounds each of the flexible substrate regions 30 d. The flexible substrate region 30d and the intermediate region 30i are only different portions of one continuous resin film 30, and need not be physically distinguished. In other words, in the resin film 30, a portion located immediately below each functional layer region 20 is a flexible substrate region 30d, and the other portion is an intermediate region 30 i.
Each of the plurality of functional layer regions 20 ultimately constitutes a panel of the flexible OLED device. In other words, the stacked structural body 100 has a structure in which a plurality of flexible OLED devices before division are supported by one substrate 10. Each functional layer region 20 has, for example, a shape having therein a thickness (dimension in the Z-axis direction) of several tens μm, a length (dimension in the X-axis direction) of about 12cm, and a width (dimension in the Y-axis direction) of about 7 cm. These dimensions may be set to any size according to the size of the desired display screen. In the illustrated example, the shape of each functional layer region 20 in the XY plane is a rectangle, but is not limited thereto. The shape of each functional layer region 20 in the XY plane may also be a square, a polygon, or a shape containing a curve in outline.
As shown in fig. 1A, the flexible substrate regions 30d are two-dimensionally arranged in a matrix corresponding to the arrangement of the flexible OLED devices. The intermediate region 30i is formed of a plurality of orthogonal stripes and is formed with a lattice pattern. The width of the stripe is, for example, about 1 to 4 mm. The flexible substrate region 30d of the resin film 30 functions as a "flexible substrate" of each flexible OLED device in the form of a final product. In contrast, the intermediate region 30i of the resin film 30 is not an element constituting the final product.
In the embodiment of the present disclosure, the structure of the laminated structure 100 is not limited to the illustrated example. The number of functional layer regions 20 (the number of OLED devices) supported by one substrate 10 is not necessarily plural, and may be single. When the functional layer regions 20 are single, the intermediate region 30i of the resin film 30 forms a simple frame pattern surrounding the periphery of one functional layer region 20.
Further, the size or proportion of each element illustrated in each drawing is determined from a viewpoint of easy understanding, and does not necessarily reflect the actual size or proportion.
Supporting substrate
Referring to fig. 2A and 2B, a method of manufacturing a support substrate in an embodiment of the present disclosure is described. Fig. 2A and 2B are process cross-sectional views illustrating a method of manufacturing the support substrate 200 in the embodiment of the present disclosure.
First, as shown in fig. 2A, a substrate 10 is prepared. The base 10 is a carrier substrate for the process, and may have a thickness of, for example, about 0.3 to 0.7 mm. The substrate 10 is typically made of glass. The substrate 10 needs to transmit the irradiated peeling light in the subsequent process.
Next, as shown in fig. 2B, a release layer 12 is formed on the substrate 10. The release layer 12 is made of polycrystalline body of tantalum nitride. The tantalum nitride may have various phases representing different composition ratios. When the ratio of tantalum atoms to nitrogen atoms is 1: 1, a stable phase of tantalum nitride can be formed. The stable phase is a crystal having a CoSn type structure in a standard state. Although the crystal structure of the stable phase is hexagonal, it is not the closest packing but an interstitial intermetallic compound (solid solution or alloy) in which nitrogen atoms are embedded between tantalum atoms and tantalum atoms. Tantalum nitride tends to form compounds of non-stoichiometric composition due to the deficiency and excess of nitrogen atoms. When depositing tantalum nitride films, nitrogen can be enriched by over-supplying it. In one embodiment of the present disclosure, the release layer 12 is made of nitrogen-rich tantalum nitride (TaN)x：1＜x is less than or equal to 2.5).
Nitrogen-rich tantalum nitride has excellent thermal conductivity. Therefore, when heat is generated by irradiation of the peeling light, even if the peeling light intensity is not uniformly distributed in space, peeling failure is less likely to occur. More specifically, when dust adheres to the back surface of the substrate 10 or scratches are formed, if peeling light is made incident on the release layer 12 from the back surface of the substrate 10, the peeling light intensity in the release layer 12 may be locally lowered by diffraction/reflection or the like caused by the shadow of the dust or scratches. When the resin film 30 is peeled off by a photochemical reaction, if such a local deficiency in the peeling light intensity occurs, peeling cannot be performed at the position, and a problem arises in that peeling failure occurs.
However, since the release layer 12 in the present embodiment absorbs the peeling light to generate heat and transfers the heat, the above-described problem due to a local shortage of the peeling light intensity can be avoided.
The tantalum nitride may be deposited by, for example, reactive sputtering. The reactive sputtering method can be performed by sputtering a tantalum target in a nitrogen-containing gas atmosphere. The nitrogen-containing gas atmosphere is, for example, a mixed gas of nitrogen and an inert gas such as argon. When the flow rate of the mixed gas is 125sccm, the flow rate of nitrogen gas may be, for example, 100 to 115sccm, and the flow rate of argon gas may be, for example, 15 to 25 sccm. It is not necessary to heat the substrate 10 during sputtering. Such a sputtering method enables the release layer 12 to be formed at a lower cost than the chemical vapor deposition method. In addition, when tantalum nitride is deposited by the reactive sputtering method, the residual internal stress in the deposited film of tantalum nitride can be reduced by adjusting the gas flow rate and the substrate temperature. In general, a relatively large residual internal stress may occur in a deposited film of a high melting point metal. If the residual internal stress of the release layer increases, the support substrate may warp and the lift-off process may not be performed properly. By forming the release layer from tantalum nitride, warpage of the support substrate can be reduced and peeling can be performed with higher yield than in the case of using the release layer formed from a high-melting-point metal.
As illustrated in the region surrounded by the broken line of fig. 2B, the nitrogen-rich deposited film of tantalum nitride (release layer 12) has irregularities on the surface. The pattern of the irregularities may have, for example, a shape and a size (several tens nm to several hundreds nm) for diffusing and reflecting visible light. The release layer 12 made of tantalum nitride may have a thickness of 50nm or more and 500nm or less, and may have a thickness of about 200nm, for example. When the thickness is less than 50nm, the film thickness necessary for functioning as a release layer may not be obtained in a part of the surface of the support substrate due to surface unevenness and unevenness in film formation rate. In addition, if it exceeds 500nm, the influence of stress cannot be ignored. Further, the thickness of the release layer 12 is more preferably 250nm or less in view of saving consumption of the tantalum target as much as possible. Nitrogen-rich tantalum nitride has no metallic luster and appears black or brown when observed. The nitrogen-rich tantalum nitride has the property of absorbing at least a portion of visible light and ultraviolet light. In this respect, tantalum nitride is significantly different from a high melting point metal such as molybdenum (Mo) which exhibits metallic luster. In addition, since the nitrogen-rich tantalum nitride can trap oxygen to be oxidized, it can function as a barrier layer against oxygen diffused from the outside and can perform a sealing effect.
The release layer 12 in the embodiment of the present disclosure has unevenness on the surface in addition to the above, and efficiently absorbs the ultraviolet laser light, and therefore, there is no need for a termination process of the laser light reflected by the peeling light in the peeling light irradiation step described later.
The structure and the manufacturing method of the laminated structure 100 will be described in more detail below.
First, fig. 3A is referred to. Fig. 3A is a cross-sectional view showing the support substrate 200 having the resin film 30 formed on the surface thereof.
The resin film 30 in the present embodiment is, for example, a polyimide film having a thickness of 5 μm or more and 20 μm or less, for example, about 10 μm. The polyimide film may be made of polyamic acid or polyimide solution as a precursor. The polyimide film may be thermally imidized after forming a film of polyamic acid on the surface of the release layer 12 in the support substrate 200, or may be formed on the surface of the release layer 12 from a polyimide solution obtained by melting polyimide or dissolving polyimide in an organic solvent. The polyimide solution can be obtained by dissolving known polyimide in any organic solvent. The polyimide film may be formed by coating a polyimide solution onto the surface of the substrate 10 and then drying.
In the case of a bottom emission type flexible display, preferably, the polyimide film achieves high transmittance in the entire visible light region. The transparency of the polyimide film can be expressed by the total light transmittance according to JIS K7105-1981, for example. The total light transmittance may be set to 80% or more or 85% or more. On the other hand, in the case of a top emission type flexible display, the transmittance is not affected.
The resin film 30 may be a film made of a synthetic resin other than polyimide. However, in the embodiment of the present disclosure, in the process of forming the thin film transistor, since the heat treatment of, for example, 350 ℃ or more is performed, the resin film 30 is made of a material that is not deteriorated by the heat treatment.
The resin film 30 may be a laminate of a plurality of synthetic resin films. In one aspect of the present embodiment, LLO of irradiating ultraviolet laser light (wavelength: 300 to 360nm) transmitted through the substrate 10 to the resin film 30 is performed when peeling the structure of the flexible display from the substrate 10. Since the release layer 12 that absorbs laser light and generates heat is disposed between the base 10 and the resin film 30, by irradiation of the ultraviolet laser light, a part (layered portion) of the resin film 30 can be vaporized at the interface between the release layer 12 and the resin film 30, and the resin film 30 can be easily peeled off from the release layer 12, that is, the support substrate 200. The release layer 12 is provided, and also has an effect of suppressing the generation of ash.
The release layer 12 in the embodiment of the present disclosure is made of black or brown tantalum nitride, and also has irregularities on the surface, so that the transmittance of the release layer 12 to ultraviolet laser light is extremely low. Thus, the release layer 12 functions as an ultraviolet shielding layer in a lift off (LLO) process. As a result, the incidence of ultraviolet laser light from the substrate 10 to the functional layer region 20 to deteriorate the characteristics of the TFT layer 20A and the OLED layer 20B is avoided or suppressed.
It is generally considered that the resin film 30 having high transparency absorbs almost all of the ultraviolet rays. However, since the resin film 30 used in the flexible OLED device is an extremely thin layer, if the release layer 12 made of a metal material is not present, the ultraviolet laser light is incident to the functional layer region 20. The ultraviolet rays deteriorate not only the characteristics of the TFT layer 20A and the OLED layer 20B but also the encapsulation performance of the organic film and the inorganic film constituting the encapsulation structure. Further, since the resin film 30 widely used at present is formed of a polyimide material having a yellowish brown color or a tan color, it has not been recognized that transmission of an ultraviolet laser causes deterioration in characteristics of the functional layer region. This is because such a polyimide material having low transparency strongly absorbs ultraviolet laser light. However, according to the studies of the present inventors, it has been found that even if the resin film 30 is low in transparency, the ultraviolet laser light can reach the functional layer region 20 as long as the thickness thereof is, for example, about 5 to 20 μm. Therefore, the method according to the embodiment of the present disclosure is applicable not only to an OLED device including a resin film (flexible substrate) made of a material having high transparency and easily transmitting ultraviolet rays, but also to the manufacture of an OLED device provided with a resin film 30 having low transparency and being thin (thickness: about 5 to 20 μm).
< polishing treatment >
When a polishing object (target) such as particles or convex portions is present on the surface 30x of the resin film 30, the target may be polished by a polishing apparatus to be planarized. Foreign matter such as particles can be detected by processing an image acquired by an image sensor, for example. The planarization process may be performed on the surface 30x of the resin film 30 after the polishing process. The planarization treatment includes a step of forming a film (planarization film) for improving the planarization on the surface 30x of the resin film 30. The planarization film does not have to be formed of resin.
< lower gas barrier film >
Next, a gas barrier film (not shown) may be formed on the resin film 30. The gas barrier film may have various structures. Examples of the gas barrier film are films such as a silicon oxide film or a silicon nitride film. Another example of the gas barrier film may be a multilayer film in which an organic material layer and an inorganic material layer are laminated. This gas barrier film may also be referred to as an "underlying gas barrier film" so as to be separated from a gas barrier film described later that covers the functional layer region 20. In addition, the gas barrier film of the functional layer region 20 may be referred to as an "upper layer gas barrier film".
< functional layer area >
Next, a process of forming the functional layer region 20 including the TFT layer 20A and the OLED layer 20B and the upper layer gas barrier film 40 will be described.
First, as shown in fig. 3B, a plurality of functional layer regions 20 are formed on a substrate 10. The release layer 12 and the resin film 30 fixed to the substrate 10 are located between the substrate 10 and the functional layer region 20.
More specifically, the functional layer region 20 includes a TFT layer 20A positioned at a lower layer and an OLED layer 20B positioned at an upper layer. The TFT layer 20A and the OLED layer 20B are sequentially formed by a known method. The TFT layer 20A includes a TFT array circuit implementing an active matrix. OLED layer 20B includes an array of OLED elements that can be driven independently of each other. The thickness of the TFT layer 20A is, for example, 4 μm, and the thickness of the OLED layer 20B is, for example, 1 μm.
Fig. 4 is a basic equivalent circuit diagram of a sub-pixel in an organic EL (Electro Luminescence) display. One pixel of the display may be composed of sub-pixels of different colors, e.g. R (red), G (green) and B (blue). The example shown in fig. 4 has a selection TFT element Tr1, a driving TFT element Tr2, a storage capacitor CH, and an OLED element EL. The selection TFT element Tr1 is connected to the data line DL and the selection line SL. The data lines DL are wirings for transmitting data signals for specifying an image to be displayed. The data line DL is electrically connected to the gate of the driving TFT element Tr2 via the selecting TFT element Tr 1. The selection line SL is a wiring for transmitting a signal for controlling on/off of the selection TFT element Tr 1. The driving TFT element Tr2 controls the on state between the power supply line PL and the OLED element EL. When the driving TFT element Tr2 is turned on, a current flows from the power supply line PL to the ground line GL through the OLED element EL. This current causes the OLED element EL to emit light. Even when the selection TFT element Tr1 is turned off, the holding capacitor CH maintains the driving TFT element Tr2 in an on state.
The TFT layer 20A includes a selection TFT element Tr1, a driving TFT element Tr2, a data line DL, a selection line SL, and the like. The OLED layer 20B includes an OLED element EL. Before the OLED layer 20B is formed, the upper surface of the TFT layer 20A is planarized by an interlayer insulating film covering the TFT array and various wirings. The structure supporting OLED layer 20B and enabling active matrix driving of OLED layer 20B is referred to as a "backplane".
Part of the circuit elements and wirings shown in fig. 4 may be included in either of the TFT layer 20A and the OLED layer 20B. The wiring shown in fig. 4 is connected to a driver circuit (not shown).
In the embodiments of the present disclosure, the specific configurations of the TFT layer 20A and the OLED layer 20B may be various. These configurations do not limit the disclosure. The TFT element included in the TFT layer 20A may be of a bottom gate type or a top gate type. Further, the light emission of the OLED element included in the OLED layer 20B may be a bottom emission type or may also be a top emission type. The specific configuration of the OLED element is also arbitrary.
The material of the semiconductor layer constituting the TFT element includes, for example, crystalline silicon, amorphous silicon, and an oxide semiconductor. In the embodiment of the present disclosure, in order to improve the performance of the TFT element, a part of the step of forming the TFT layer 20A includes a heat treatment step at 350 ℃.
< Upper gas Barrier film >
After the functional layer region 20 is formed, as shown in fig. 3C, the entire functional layer region 20 is covered with a gas barrier film (upper gas barrier film) 40, a typical example of the upper gas barrier film 40 is a multilayer film in which an inorganic material layer and an organic material layer are laminated, an adhesive film, other functional layers constituting a touch panel, a polarizing film, and the like may be disposed between the upper gas barrier film 40 and the functional layer region 20, or on an upper layer of the upper gas barrier film 40, the upper gas barrier film 40 may be formed by a Thin Film Encapsulation (TFE) technique, and from the viewpoint of package reliability, a WVTR (Water Vapor Transmission Rate) as a thin film Encapsulation structure typically obtains 1 × 10-4g/m2And/day is less. According to embodiments of the present disclosure, the standard is then fulfilled. The thickness of the upper gas barrier film 40 is, for example, 1.5 μm or less.
Fig. 5 is a perspective view schematically showing the upper surface side of the laminated structure 100 at the stage where the upper layer gas barrier film 40 is formed. One stacked structure 100 contains a plurality of OLED devices 1000 supported by a substrate 10. In the example illustrated in fig. 5, one laminated structure 100 includes more functional layer regions 20 than the example illustrated in fig. 1A. As described above, the number of functional layer regions 20 supported by one substrate 10 is arbitrary.
< protective sheet >
Next, fig. 3D is referred to. As shown in fig. 3D, the protective sheet 50 is attached to the upper surface of the laminated structure 100. The protective sheet 50 may be made of a material such as polyethylene terephthalate (PET), polyvinyl chloride (PVC), or the like. As described above, the typical example of the protective sheet 50 has a laminated structure having a release agent coating layer on the surface thereof. The thickness of the protective sheet 50 may be, for example, 50 μm or more and 150 μm or less.
The laminated structure body 100 manufactured in this way is prepared, and then the manufacturing method according to the present disclosure can be performed using the above-described manufacturing apparatus (peeling apparatus 220).
The laminated structure body 100 that can be used in the manufacturing method of the present disclosure is not limited to the example shown in fig. 1A and 1B. The protective sheet 50 may also cover the entire resin film 30 and be enlarged to the outside of the resin film 30. Alternatively, the protective sheet 50 may also cover the entire resin film 30 and may be expanded to the outside of the substrate 10. As described later, after the substrate 10 is separated from the laminated structure 100, the laminated structure 100 becomes a flexible sheet-like structure having no rigidity. In the peeling process and the post-peeling process of the substrate 10, the protective sheet 50 functions to protect the functional layer region 20 from impact, friction, and the like when the functional layer region 20 collides with or comes into contact with an external device, an instrument, or the like. Since the protective sheet 50 is eventually peeled from the laminated structure 100, a typical example of the protective sheet 50 has a laminated structure having an adhesive layer (a release agent coating layer) having relatively low adhesion on the surface. A more detailed description of the laminated structure 100 will be described later.
< OLED device division >
In the method of manufacturing the flexible OLED device of the present embodiment, after the step of preparing the laminated structure 100 is performed, the step of dividing each of the intermediate region 30i and the plurality of flexible substrate regions 30d of the resin film 30 is performed. The splitting process may also be performed after the LLO process and not necessarily before the LLO process.
The division may be performed by breaking the central portions of the adjacent OLED devices with a laser beam or a cutter. In the present embodiment, the portion of the laminated structure other than the base 10 is cut off without cutting off the base 10. However, it is also possible to break the substrate 10 and thereby divide it into partial stacked structures comprising a single OLED device and a portion of the substrate supporting each OLED device.
The step of cutting off the laminated structure other than the base 10 by irradiation with a laser beam will be described below. The irradiation position of the laser beam for disconnection is along the outer periphery of each flexible substrate region 30 d.
Fig. 6A and 6B are a cross-sectional view and a plan view schematically showing the positions of the intermediate region 30i and each of the plurality of flexible substrate regions 30d of the divided resin film 30. The irradiation position of the laser beam for disconnection is along the outer periphery of each flexible substrate region 30 d. In fig. 6A and 6B, an irradiation position (off position) CT indicated by an arrow or a broken line is irradiated with a laser beam for off, and a portion other than the substrate 10 in the stacked structural body 100 is divided into a plurality of OLED devices 1000 and other unnecessary portions. Due to the disconnection, a gap of several tens μm to several hundreds μm is formed between each OLED device 1000 and the periphery thereof. As described above, such disconnection may be performed by the cutter instead of irradiation of the laser beam. The OLED device 1000 and other unwanted parts are also fixed to the substrate 10 after disconnection.
As shown in fig. 6B, the planar layout of the "unnecessary portion" in the laminated structural body 100 matches the planar layout of the middle region 30i of the resin film 30. In the illustrated example, the "unwanted portion" is a continuous piece of sheet-like structure having an opening. However, the embodiments of the present disclosure are not limited to this example. The irradiation position CT of the off laser beam may be set so that the "unnecessary portion" is divided into a plurality of portions. Further, the sheet-like structure, which is the "unnecessary portion", includes not only the intermediate region 30i of the resin film 30 but also the broken portion of the laminated body (for example, the gas barrier film 40 and the protective sheet 50) existing on the intermediate region 30 i.
In the case of the cutting by the laser beam, the wavelength of the laser beam may be in any region of infrared rays, visible rays, or ultraviolet rays. From the viewpoint of reducing the influence of the disconnection on the substrate 10, a laser beam having a wavelength included in the green to ultraviolet regions is desired. For example, according to Nd: YAG laser devices can be switched off using the second harmonic (532 nm wavelength) or the third harmonic (343 nm or 355nm wavelength). In this case, if the laser output is adjusted to 1 to 3W and scanned at a speed of about 500mm per second, the stack supported by the substrate 10 can be broken (divided) into the OLED device and unnecessary portions without causing damage to the substrate 10.
According to the embodiment of the present disclosure, the timing of the disconnection is earlier than that of the conventional art. Since the disconnection is performed in a state where the resin film 30 has been fixed to the substrate 10, the location of the disconnection position can be performed with high accuracy and high precision even if the interval between the adjacent OLED devices 1000 is small. Accordingly, the spacing between adjacent OLED devices 1000 may be reduced to reduce the unwanted portions that are ultimately not needed.
< irradiation of stripping light >
Fig. 7A is a diagram schematically showing a state before the stage 212 supports the laminated structure 100 in a manufacturing apparatus (peeling apparatus) not shown. The stage 212 in this embodiment is an adsorption stage having a large number of holes for adsorption on the surface. The configuration of the suction table is not limited to this example, and may include an electrostatic chuck or other fixing device for supporting the laminated structure. The stacked structural body 100 is disposed such that the second surface 100b of the stacked structural body 100 faces the surface 212S of the stage 212, and is in close contact with the stage 212.
Fig. 7B is a diagram schematically showing a state in which the laminated structure 100 is supported by the stage 212. The arrangement relationship between the stage 212 and the laminated structure 100 is not limited to the illustrated example. For example, the top-bottom position of the stacked structure 100 may be reversed, and the stage 212 is located below the stacked structure 100.
In the example shown in fig. 7B, the stacked structural body 100 is in contact with the surface 212S of the stage 212, and the stage 212 adsorbs the stacked structural body 100.
Next, as shown in fig. 7C, the release layer 12 located between the plurality of flexible substrate regions 30d of the resin film 30 and the base 10 is irradiated with laser light (peeling light) 216. Fig. 7C is a diagram schematically showing a state where the release layer 12 is irradiated from one side of the substrate 10 with the peeling light 216 formed linearly extending in the vertical direction of the paper surface of the drawing. The release layer 12 absorbs the ultraviolet laser light and is heated in a short time. At the interface between the release layer 12 and the resin film 30, a part of the resin film 30 is vaporized or decomposed (disappeared) by the heat from the release layer 12. By scanning the release layer 12 with the peeling light 216, the degree of adhesion of the resin film 30 to the release layer 12, i.e., the support substrate 200, is reduced. The wavelength of the stripping light 216 is typically in the ultraviolet region. The absorbance of the substrate 10 is about 10% in the region of 343 to 355nm wavelength, for example, but may be increased to 30 to 60% at 308 nm.
The irradiation with the stripping light in the present embodiment will be described in detail below.
The stripping means in this embodiment includes a beam light source that emits a stripping light 216. The beam light source includes a laser device and an optical system for shaping laser light emitted from the laser device into a beam shape.
Fig. 8A is a perspective view schematically showing a case where the laminated structure 100 is irradiated with a linear beam (stripping light 216) emitted from the beam light source 214 of the stripping device 220. For ease of understanding, the stage 212, the stacked structural body 100, and the beam light source 214 are illustrated in a separated state in the Z-axis direction of the drawing. When the peeling light 216 is irradiated, the second surface 100b of the stacked structural body 100 is in contact with the stage 212.
The position of the stage 216 upon irradiation with the stripping light 216 is schematically shown in fig. 8B. Although not illustrated in fig. 8B, the stacked structural body 100 is supported by the stage 212.
Examples of the laser device that emits the stripping light 216 include a gas laser device such as an excimer laser, a solid-state laser device such as a YAG laser, a semiconductor laser device, and othersA laser device. According to the XeCl excimer laser device, laser light having a wavelength of 308nm can be obtained. When yttrium-vanadium tetraoxide (YVO) doped with neodymium (Nd) is used4) Or YVO doped with (Yb)4In the case of a laser oscillation medium, the wavelength of laser light (fundamental wave) emitted from the laser oscillation medium is about 1000nm, and therefore, the laser light can be used after being converted into laser light (third harmonic) having a wavelength of 340 to 360nm by a wavelength conversion element.
From the viewpoint of suppressing the generation of soot, it is more effective to use a laser beam having a wavelength of 308nm obtained by an excimer laser device than to use a laser beam having a wavelength of 340 to 360 nm. In addition, the presence of the release layer 12 exerts a remarkable effect of suppressing the generation of ash.
The irradiation of the stripping light 216 may be performed at, for example, 50 to 300mJ/cm2The energy irradiation density of (2) is performed. The bundle-like peeling light 216 has a line length (long axis dimension, Y axis direction dimension in fig. 8B) that traverses the dimension of the substrate 10, i.e., the length of one side of the substrate. The wire length may be, for example, 750mm or more. On the other hand, the line width (the minor axis dimension, the dimension in the X axis direction in fig. 8B) of the peeling light 216 may be, for example, about 0.2 mm. These dimensions are the dimensions of the irradiated area at the interface between the resin film 30 and the substrate 10. The stripping light 216 may be pulsed or continuous wave illuminated. The pulsed irradiation may be performed, for example, at a frequency of about 200 times per second.
The irradiation position of the peeling light 216 is moved relative to the substrate 10, and scanning of the peeling light 216 is performed. In the peeling apparatus 220, the light source 214 for emitting peeling light and an optical device (not shown) are fixed, and the laminated structure 100 is movable, or vice versa. In the present embodiment, the irradiation of the stripping light 216 is performed while the stage 212 moves from the position shown in fig. 8B to the position shown in fig. 8C. That is, the scanning of the peeling light 216 is performed by the movement of the stage 212 in the X-axis direction.
In this embodiment, since the specular reflection of the ultraviolet laser light by the release layer is suppressed, it is not necessary to perform the end processing of the reflected laser light. When the release layer is formed of a metal film that causes specular reflection of the ultraviolet laser, the ultraviolet laser may be incident obliquely to the release layer at an angle of 5 to 15 degrees. In the present embodiment, such oblique irradiation does not have to be performed.
< peeling >
Fig. 9A shows a state in which the laminated structure 100 is in contact with the stage 212 after irradiation of the peeling light. While maintaining this state, the distance from the stage 212 to the substrate 10 is enlarged. At this time, the stage 212 in the present embodiment adsorbs the OLED device portion of the laminated structure 100.
A driving device (not shown) holds the substrate 10 to move the entire substrate 10 in the arrow direction, thereby performing Lift Off (Lift Off). The substrate 10 can move together with the suction stage while being sucked by the suction stage not shown. The moving direction of the substrate 10 may also be inclined, not necessarily perpendicular to the first surface 100a of the stacked structural body 100. The movement of the substrate 10 may also be a rotational movement, not necessarily a linear movement. The substrate 10 may be fixed by a holding device or another table, not shown, and the table 212 may be moved upward in the figure.
Fig. 9B is a sectional view showing the first part 110 and the second part 120 of the stacked structural body 100 separated in this way. The first portion 110 of the stacked structure 100 includes a plurality of OLED devices 1000 in contact with the mesa 212. Each OLED device 1000 has a plurality of flexible substrate regions 30d of the functional layer region 20 and the resin film 30. In contrast, the second portion 120 of the laminated structure 100 has the substrate 10 and the release layer 12.
Each OLED device 1000 supported by the table 212 can be easily removed from the table 212 simultaneously or sequentially because it is in a disconnected relationship with each other.
In the above embodiment, the disconnection and separation of each OLED device 1000 is performed before the LLO process, but the disconnection and separation of each OLED device 1000 may be performed after the LLO process. Furthermore, the disconnection and separation of each OLED device 1000 may also include dividing the substrate 10 into corresponding portions.
Fig. 10 is a cross-sectional view schematically illustrating the unevenness in the rear surface of the flexible substrate region 30d of the OLED device 1000. The back surface of the resin film (flexible film) 30 has irregularities that match the irregularity pattern provided on the surface of the release layer 12. The irregularities have a shape and a size for diffusing and reflecting visible light. OLED device 1000 may also include a support film bonded to the back side of flexible substrate region 30 d. When the resin film 30 has a thickness of, for example, about 5 to 20 μm, the support film can be attached. The presence of the irregularities on the back surface of the resin film 30 increases the bonding area with respect to the support film and enhances the anchor effect, thus enhancing the bonding strength between the flexible substrate region 30d and the support film.
According to the embodiments of the present disclosure, even in the case of using a flexible film made of polyimide and PET which are high in transparency to transmit ultraviolet rays, or in the case of using a flexible film which is low in transparency, thin (5 to 20 μm in thickness), and transparent to ultraviolet rays, it is possible to suppress deterioration of characteristics of a functional layer region and deterioration of performance of a gas barrier layer due to ultraviolet rays.
Industrial applicability
Embodiments of the present invention provide a new method of manufacturing a flexible OLED device. The flexible OLED device can be widely applied to smart phones, flat panel terminals, vehicle-mounted displays and medium-sized to large-sized television devices.
Description of the reference numerals
10 … base, 12 … release layer, 20 … functional layer region, 20a … TFT layer, 20B … OLED layer, 30 … resin film, flexible substrate region of 30d … resin film, middle region of 30i … resin film, 40 … gas barrier film, 50 … protective sheet, 100 … laminated structure, 212 … stand, 1000 … OLED device
