阅读说明：本技术 柔性oled装置的制造方法以及支承基板
(Method for manufacturing flexible OLED device and supporting substrate
) 是由 岸本克彦 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)的工序,所述层叠结构体具备基座(10)、包括TFT层和OLED层的功能层区域(20)、位于基座与功能层区域之间并支承功能层区域的柔性膜(30)、以及位于柔性膜与基座之间并粘合于基座的释放层(12)。利用透过基座的剥离光(216)来照射释放层并从释放层上剥离柔性膜。释放层由铝和硅的合金形成。(According to the manufacturing method of the flexible OLED device, the step of preparing a laminated structure (100) is provided, wherein the laminated structure comprises a base (10), a functional layer area (20) comprising a TFT layer and an OLED layer, a flexible film (30) located between the base and the functional layer area and used for supporting the functional layer area, and a release layer (12) located between the flexible film and the base and bonded to the base. The release layer is irradiated with a peeling light (216) transmitted through the base and the flexible film is peeled from the release layer. The release layer is formed of an alloy of aluminum and silicon.)
1. A method of manufacturing a flexible OLED device,
the manufacturing method comprises the following steps:
preparing a laminated structure including a base, a functional layer region including a TFT layer and an OLED layer, a flexible film positioned between the base and the functional layer region and supporting the functional layer region, and a release layer positioned between the flexible film and the base and bonded to the base; and
a step of irradiating the release layer with ultraviolet laser light transmitted through the base and peeling the flexible film from the release layer,
the release layer is formed of an alloy of aluminum and silicon.
2. The manufacturing method according to claim 1,
the weight ratio of silicon contained in the alloy is 4% to 20%.
3. The manufacturing method according to claim 1 or 2,
the release layer has a linear expansion coefficient of 30% or more and 500% or less of the linear expansion coefficient of the flexible film.
4. The manufacturing method according to any one of claims 1 to 3,
the thickness of the release layer is 100nm or more and 5000nm or less.
5. The manufacturing method according to any one of claims 1 to 4,
the wavelength of the ultraviolet laser is more than 300nm and less than 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:
forming the release layer on the susceptor by sputtering an aluminum target containing silicon; and
and a step of forming the flexible film on the release layer.
8. The manufacturing method according to any one of claims 1 to 7, characterized by further comprising:
and removing and recovering the release layer from the base after peeling the flexible film from the release layer.
9. A support substrate for a flexible OLED device,
the support substrate includes:
a release layer formed of an alloy of aluminum and silicon; and
a base formed of a material that transmits ultraviolet rays and supporting the release layer.
10. The support substrate of claim 9,
the support substrate further includes a flexible film made of a material that transmits the ultraviolet light, and the flexible film covers the release layer.
11. The support substrate according to claim 9 or 10,
the weight ratio of silicon contained in the alloy is 4% to 20%.
12. The support substrate according to any one of claims 9 to 11,
the release layer has a linear expansion coefficient of 30% or more and 500% or less of the linear expansion coefficient of the flexible film.
13. The support substrate according to any one of claims 9 to 12,
the thickness of the release layer is 100nm or more and 5000nm or less.
Technical Field
The present disclosure relates to a method of manufacturing a flexible OLED device and a support substrate.
Background
A typical example of the flexible display includes a Film made of a synthetic resin such as polyimide (hereinafter referred to as a "resin Film") and elements such as a TFT (Thin Film Transistor) and an OLED (Organic Light Emitting Diode) supported by the resin Film. 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 sealed by a gas barrier film (sealing film).
The flexible display can be manufactured using a glass base having a resin film formed on the upper surface thereof. The glass base functions as a support (carrier) for maintaining the shape of the resin film in a planar shape in the production process. By forming elements such as TFTs and OLEDs, and a gas barrier film, etc. on a resin film, the structure of the flexible OLED device is realized in a state of being supported on a glass base. The flexible OLED device is then peeled off the glass substrate, thereby achieving flexibility. The entire portion in which elements such as TFTs and OLEDs are arranged can be referred to as a "functional layer region".
Patent document 1 discloses a method for peeling a flexible substrate on which an OLED device is mounted from a glass base by irradiating an interface between the flexible substrate and the glass base with ultraviolet laser light (peeling light). In the method disclosed in patent document 1, an amorphous silicon layer is disposed between a flexible substrate and a glass base. The irradiation of the ultraviolet laser light causes the amorphous silicon layer to generate hydrogen gas, thereby peeling the flexible substrate from the glass base.
Prior art documents
Patent document
Patent document 1: international publication No. 2009/037797
Disclosure of Invention
Technical problem to be solved by the invention
Conventionally, since a resin film used for a flexible substrate absorbs ultraviolet rays, the influence of peeling light irradiation on a TFT element and an OLED element has not been particularly studied. According to the study by the present inventors, it was found that the ultraviolet laser used in the peeling step may deteriorate the TFT element and the OLED element.
The present disclosure provides a novel method for manufacturing a flexible OLED device and a support substrate that can solve the above problems.
Technical solution for solving technical problem
In an exemplary embodiment, a method of manufacturing a flexible OLED device of the present disclosure includes: preparing a laminated structure including a base, a functional layer region including a TFT layer and an OLED layer, a flexible film positioned between the base and the functional layer region and supporting the functional layer region, and a release layer positioned between the flexible film and the base and bonded to the base; and a step of irradiating the release layer with ultraviolet laser light transmitted through the base to peel the flexible film from the release layer. The release layer is formed of an alloy of aluminum and silicon.
In some embodiments, the alloy contains silicon in a weight ratio of 4% or more and 20% or less.
In some embodiments, the release layer has a coefficient of linear expansion that is 30% or more and 500% or less of the coefficient of linear expansion of the flexible film.
In some embodiments, the release layer has a thickness of 100nm or more and 5000nm or less.
In some embodiments, the wavelength of the ultraviolet laser is 300nm or more and 360nm or less.
In some embodiments, the flexible film has a thickness of 5 μm or more and 20 μm or less.
In some embodiments, the step of preparing the laminated structure comprises: forming the release layer on the susceptor by sputtering an aluminum target containing silicon; and a step of forming the flexible film on the release layer.
In some embodiments, the method of manufacturing further comprises: and removing and recovering the release layer from the base after peeling the flexible film from the release layer.
In an exemplary embodiment, a support substrate of the present disclosure is a support substrate of a flexible OLED device, including: a release layer formed of an alloy of aluminum and silicon; and a base which is formed of a material that transmits ultraviolet rays and supports the release layer.
In some embodiments, the support substrate further includes a flexible film formed of a material that transmits the ultraviolet rays, and the flexible film covers the release layer.
In some embodiments, the alloy contains silicon in a weight ratio of 4% or more and 20% or less.
In some embodiments, the release layer has a coefficient of linear expansion that is 30% or more and 500% or less of the coefficient of linear expansion of the flexible film.
In some embodiments, the release layer has a thickness of 100nm or more and 5000nm or less.
Advantageous effects
According to an embodiment of the present invention, a novel method for manufacturing a flexible OLED device and a supporting substrate are provided to solve the above problems.
Drawings
Fig. 1A is a plan view showing a configuration example of a stacked structure used in the method of manufacturing a flexible OLED device of the present disclosure.
Fig. 1B is a cross-sectional view of the stacked structural body 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 1 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 sectional view schematically showing a cutting position of the laminated structure.
Fig. 6B is a plan view schematically showing a cutting position of the laminated structure.
Fig. 7A is a diagram schematically showing a state immediately before the table supports the laminated structure.
Fig. 7B is a diagram schematically showing a state in which the laminated structure is supported by the table.
Fig. 7C is a view schematically showing a state in which the interface between the base of the laminated structure and the resin film is irradiated with laser light (peeling light) shaped into a linear shape.
Fig. 8A is a perspective view schematically showing a state in which the laminated structure is irradiated with a line beam emitted from a line beam light source of the peeling apparatus.
Fig. 8B is a diagram schematically showing the position of the stage at the start of irradiation of the peeling light.
Fig. 8C is a diagram schematically showing the position of the stage at the end of irradiation of the peeling light.
Fig. 9A is a cross-sectional view schematically showing a state before the laminated structure is separated into the first portion and the second portion after the peeling light is irradiated.
Fig. 9B is a sectional view schematically showing a state where the stacked structural body is separated into the first portion and the second portion.
Detailed Description
Since Laser Lift Off (LLO) for peeling the flexible substrate from the glass base is performed, there are cases where a release layer is provided between the glass base and the flexible substrate and cases where no release layer is provided.
In the case where the release layer is not provided, although the manufacturing cost is reduced, the yield of peeling is reduced. More specifically, there are the following problems: when laser light for peeling (peeling light) is irradiated, coal-like residue which is very difficult to remove, called ash, is formed on the surfaces of both the glass base and the flexible substrate. This reduces the contact force of the support film or the like stuck to the flexible substrate after the laser lift-off process, and also hinders the reuse of the glass substrate. Further, there is a problem that the range of irradiation conditions of the laser beam that can be appropriately stripped is narrow. In contrast, when a release layer is provided, the generation of dust is reduced, and the range of laser irradiation conditions is also relatively large, so that the peeling yield is improved. The release layer is typically formed of amorphous silicon, but may also be formed of a high melting point metal (Mo, Cr, w, Ti, etc.).
Conventionally, a flexible substrate is formed of a resin material typified by polyimide. Since such a resin material absorbs ultraviolet rays, it is considered unnecessary to study the influence of peeling light irradiation on the TFT element and the OLED element. However, according to the studies of the present inventors, it was found that when the thickness of the flexible substrate is made very thin, about 5 μm to 15 μm, ultraviolet rays may not be sufficiently absorbed, and an ultraviolet laser used in the peeling step may deteriorate the TFT element and the OLED element. This problem also occurs in the case where a release layer formed of amorphous silicon is provided. This is because amorphous silicon is transparent to ultraviolet rays. However, when the release layer is formed of a high-melting metal, the high-melting metal absorbs or reflects ultraviolet rays and does not transmit them, and therefore, the influence of peeling light irradiation on the TFT element and the OLED element can be prevented. However, the use of a high melting point metal to form the release layer results in a significant increase in manufacturing costs.
The reason for using amorphous silicon or a high melting point metal as the material of the release layer is its higher melting point. That is, in order to prevent the release layer from melting due to heat generation caused by peeling light irradiation, it is considered that the release layer should be formed of a high melting point material.
However, according to the studies of the present inventors, it was found that even in the case where the release layer is formed by an alloy of aluminum and silicon having a low melting point, the release layer is not melted by the peeling light irradiation. This is because aluminum, which is a main component, has a large specific heat and latent heat of fusion, and is excellent in heat conduction. As a result, even if the release layer is locally heated by the peeling light irradiation, the generated heat is quickly conducted to the surroundings, and the release layer can be prevented from being damaged. As described later, an alloy of aluminum and silicon has a characteristic of having a lower coefficient of linear expansion than pure aluminum due to the presence of silicon. Generally, the linear expansion coefficient of metal is larger than that of glass. In particular, aluminum has a higher linear expansion coefficient than that of molybdenum, which is a high-melting metal. If the difference in the thermal expansion coefficient between the release layer and the glass base is too large, a problem arises in that a part of the release layer peels off from the glass base due to internal stress or strain. The thermal expansion coefficient of the alloy of aluminum and silicon can be adjusted in a wide range according to the silicon content ratio. Further, by adjusting the deposition conditions of the aluminum alloy, the internal stress of the deposited film can be greatly reduced as compared with the internal stress of the high melting point metal film (for example, 400 GPa). Therefore, by using an alloy of aluminum and silicon, the problem of release layer peeling can be solved. Further, compared to a high melting point metal, an inexpensive alloy of aluminum and silicon can be used as the release layer, which brings various advantages. For example, the high melting point metal material is difficult to reuse, and each glass base to which the release layer is attached needs to be disposed of after being buried as industrial waste. In contrast, an alloy of aluminum and silicon can be easily dissolved and removed by a chemical solution such as an acid, and thus the recyclability is improved. Therefore, even if the release layer is used, the manufacturing cost can be reduced as a whole.
Hereinafter, embodiments of a method and an apparatus for manufacturing a flexible OLED device according to the present disclosure will be described with reference to the drawings. In the following description, unnecessary detailed description may be omitted. For example, detailed descriptions of already known matters and repetitive descriptions of substantially the same configuration may be omitted. This is to avoid the following description becoming unnecessarily lengthy and readily understandable to those skilled in the art. The figures and the following description are provided to enable those skilled in the art to make a full understanding of the disclosure. It is not intended that the subject matter recited in the claims be limited by these contents.
< laminated Structure >
Refer to fig. 1A and 1B. In the method of manufacturing the flexible OLED device in the present embodiment, first, the stacked structure 100 illustrated 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 the line B-B. For reference, an XYZ coordinate system having X, Y, and Z axes perpendicular to each other is shown in fig. 1A and 1B.
The laminated structure 100 in the present embodiment includes a base (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 base 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 base 10 and bonded to the base 10. The release layer 12 is formed of an alloy of aluminum and silicon. The laminated structure 100 further includes a protective sheet 50 covering the plurality of functional layer regions 20, and a gas barrier film 40 covering the entire functional layer region 20 between the plurality of functional layer regions 20 and the protective sheet 50. The laminated structure 100 may have other layers, not shown, such as a buffer layer.
A typical example of the base 10 is a glass base 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 base 10 supporting the release layer 12 is collectively referred to as the "support substrate" of the flexible OLED device. The support substrate may also be provided with 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 base 10, and the second surface 100b is defined by the protective sheet 50. The base 10 and the protective sheet 50 are members that are temporarily used in the manufacturing process, and are not 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 merely different portions of the continuous 1 piece of 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 structure 100 has a structure in which one base 10 supports a plurality of flexible OLED devices before cutting. Each functional layer region 20 has a shape having 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 7cm, for example. These dimensions may be set to any size according to the size of the display screen required. The shape of each functional layer region 20 in the XY plane is rectangular in the illustrated example, but is not limited thereto. The shape of each functional layer region 20 in the XY plane may also have a square, polygonal, or outline including a curved line shape.
As shown in fig. 1A, the flexible substrate regions 30d are two-dimensionally arranged in rows and columns corresponding to the arrangement of the flexible OLED devices. The intermediate region 30i is formed of a plurality of vertical stripes, and forms 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 1 submount 10 need not be 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 block pattern surrounding the periphery of 1 functional layer region 20.
The dimensions and ratios of the elements shown in the drawings are determined from the viewpoint of easy understanding, and do not necessarily reflect the actual dimensions and ratios.
Supporting substrate
A method for manufacturing a support substrate according to an embodiment of the present disclosure will be described with reference to fig. 2A and 2B. 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, the susceptor 10 is prepared. The susceptor 10 is a carrier substrate for a process, and may have a thickness of about 0.3 to 0.7mm, for example. The base 10 is typically formed of glass. The susceptor 10 is required to transmit the peeling light to be irradiated in the subsequent process.
Next, as shown in fig. 2B, a release layer 12 is formed on the base 10. The release layer 12 is formed of an alloy of aluminum and silicon. The weight ratio of silicon contained in the alloy is 4% to 20%. By containing silicon in such a weight ratio, the release layer 12 has a lower linear expansion coefficient than that of pure aluminum (23.6 ppm/K). As described above, the absolute value of the internal stress of the release layer 12 can be reduced to 10MPa or less and the linear expansion coefficient of the release layer 12 can be made to fall within the range of 30% to 500% of the linear expansion coefficient of the resin film 30 by adjusting the silicon content and the deposition conditions of the aluminum alloy. When the weight ratio of silicon contained in the alloy is 10% or more and 15% or less, the coefficient of linear expansion of the alloy of aluminum and silicon is further minimized, and the alloy is excellent in heat resistance and wear resistance. Therefore, there is an advantage that the reuse of the base 10 forming the release layer 12 becomes easy. Thermal strain may occur in the release layer 12 that generates heat at the interface between the resin film 30 and the release layer 12 by absorbing the ultraviolet laser light. If there is a large difference (for example, a difference of 10 times or more) in the value of the linear expansion coefficient between the resin film 30 and the release layer 12, a large strain is generated in the resin film 30, and there is a possibility that a crack is generated in the lower layer gas barrier film interposed between the resin film 30 and the functional layer region 20. From this point of view, the coefficient of linear expansion of the release 12 does not need to be close to that of the base 10. The alloy of aluminum and silicon can be said to have a linear expansion coefficient in an appropriate range for both the resin film 30 and the susceptor 10.
In the present embodiment, the linear expansion coefficients (room temperature) of the TFT layer 20A, the resin film 30, the release layer 12 and the base 10 are, for example, 2 to 5ppm/K, several tens ppm/K, 19 to 23ppm/K and 3 to 5ppm/K, respectively. When a lower gas barrier film, which will be described later, is provided between the TFT layer 20A and the resin film 30, the linear expansion coefficient of the lower gas barrier film is, for example, about 2 to 5 ppm/K. In addition, the linear expansion coefficient of the transparent polyimide as the material of the resin film 30 is about 25ppm/K, and the linear expansion coefficient of polyethylene terephthalate (PET) is about 60 ppm/K. According to the study of the present inventors, the linear expansion coefficient of the release layer is preferably between the linear expansion coefficient of the base 10 and the linear expansion coefficient of the resin film 30, or is equal to or higher than the linear expansion coefficient of the base 10 and equal to or lower than 5 times the linear expansion coefficient of the resin film 30 (for example, 15 to 23ppm/K, more specifically, 15 to 20 ppm/K).
The thickness of the release layer 12 may be 100nm or more and 5000nm or less. A typical example of the method for forming the release layer 12 is a sputtering method, but the release layer 12 may be formed by an electroplating method. If the electroplating method is used, the release layer 12 having a thickness of the order of μm can be realized. Further, since the main component of the alloy constituting the release layer 12 is aluminum, the thermal conductivity of the alloy is sufficiently high, and peeling can be performed even when the alloy is thick of about several μm.
In the case of forming the release layer 12 by a sputtering method, an alloy is deposited on the susceptor 10 by sputtering an aluminum target containing silicon.
Further, after the resin film 30 is peeled off from the release layer 12 by a laser peeling step described later, the release layer 12 may be removed from the base 10 and recovered.
In addition, the main component of the aluminum alloy used in the release layer 12 is aluminum having a low melting point. The material has a large specific heat and latent heat of fusion and a good thermal conductivity, so that local heating is not likely to occur. In other words, although the aluminum alloy is a material having a lower melting point than the high melting point metal, melting of the release layer 12 does not occur when the release layer 12 is irradiated with the peeling light. Further, when heat is generated by irradiation of the peeling light, even if the spatial distribution of the peeling light intensity is not uniform, the heat is easily conducted to the surroundings, and thus peeling failure is not easily generated. More specifically, when dust adheres to or scratches are formed on the back surface of the base 10, if peeling light is incident on the release layer 12 from the back surface of the base 10, the peeling light intensity on the release layer 12 may be locally reduced due to diffraction, reflection, or the like caused by the shadow of the dust or the scratches. When the resin film 30 is peeled off by heat generated by photochemical reaction, if such a local deficiency in 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 conduct heat, the above-described problem due to a local deficiency in the intensity of the peeling light can be avoided.
Hereinafter, the structure and the manufacturing method of the laminated structure 100 will be described in more detail.
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 a polyimide film having a thickness of, for example, 5 μm or more and 20 μm or less, for example, about 10 μm. The polyimide film may be formed of polyamic acid or a polyimide solution as a precursor. The thermal imidization may be performed after a film of polyamic acid is formed on the surface of the release layer 12 in the support substrate 200, or a film may be formed on the surface of the release layer 12 by a polyimide solution in which polyimide is melted or dissolved in an organic solvent. The polyimide solution can be obtained by dissolving a known polyimide in an arbitrary organic solvent. The polyimide film may be formed by drying after applying the polyimide solution to the surface of the susceptor 10.
In the case of a flexible display of a bottom emission type, the polyimide film preferably realizes high transmittance over the entire visible light region. The transparency of the polyimide film can be described by, for example, the total light transmittance in conformity with JIS K7105-1981. The total light transmittance may be set to 80% or more or 85% or more. On the other hand, in the case of a flexible display of the top emission type, it is not affected by the transmittance.
The resin film 30 may be a film formed of a synthetic resin other than polyimide. However, in the embodiment of the present disclosure, since the heat treatment at 350 ℃ or higher is performed in the step of forming the thin film transistor, the resin film 30 is formed 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 some embodiments of the present embodiment, LLO is performed to irradiate ultraviolet laser (wavelength: 300 to 360nm) transmitted through the base 10 onto the resin film 30 when the structure of the flexible display is peeled from the base 10. Since the release layer 12 that absorbs the laser light and generates heat is disposed between the base 10 and the resin film 30, a part (layer-shaped portion) of the resin film 30 is vaporized at the interface between the release layer 12 and the resin film 30 by irradiation of the ultraviolet laser light, 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 can also provide an effect of suppressing the generation of ash.
The release layer 12 in the embodiment of the present disclosure has properties of a metal containing aluminum as a main component, and therefore, the transmittance of the release layer 12 to ultraviolet laser light is extremely low. Therefore, the release layer 12 functions as an ultraviolet shielding layer in the peeling step. As a result, the deterioration of the characteristics of the TFT layer 20A and the OLED layer 20B due to the incidence of the ultraviolet laser light from the base 10 to the functional layer region 20 is avoided or suppressed.
It is considered that almost all of the ultraviolet rays are absorbed by the resin film 30 having high transparency. 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 enters the functional layer region 20. The ultraviolet laser may deteriorate not only the characteristics of the TFT layer 20A and the OLED layer 20B but also the sealing performance of the organic film and the inorganic film constituting the sealing structure. Further, the currently widely used resin film 30 is formed of a tawny or dark brown polyimide material, and therefore, there is no recognition that the transmission of the ultraviolet laser light may cause the characteristic deterioration of the functional layer region. This is because such a polyimide material having low transparency strongly absorbs ultraviolet laser light. However, according to the study of the present inventors, it was found that even if the resin film 30 has a low transparency, the ultraviolet laser light can reach the functional layer region 20 if the thickness is only about 5 to 20 μm, for example. Therefore, the method according to the embodiment of the present disclosure is suitable for manufacturing not only an OLED device including a resin film (flexible substrate) formed of a material having high transparency and easily transmitting ultraviolet rays, but also an OLED device including a resin film 30 having low transparency and being thin (thickness: about 5 to 20 μm).
Further, polyimides and PET having high transparency and transmitting ultraviolet rays have lower heat resistance than polyimides having low transparency. However, according to the study of the present inventors, it has been found that since the release layer 12 formed of an alloy of aluminum and silicon has a large specific heat and latent heat of fusion and a good thermal conductivity as described above, heat generated by ultraviolet irradiation is rapidly conducted through the release layer 12, and even a resin film having a low heat resistance such as polyimide or PET having a high transparency does not cause damage and can be peeled off well. In other words, it was found that the release layer 12 need not be formed of a high-melting metal, and LLO can be achieved even if it is formed of a non-high-melting metal material containing aluminum as a main component.
Although forming the release layer 12 may cause an increase in manufacturing cost, unlike the high melting point metal, the aluminum alloy can be easily dissolved by the chemical solution, and thus, recycling and reuse can be achieved. Therefore, even if the release layer is employed, an increase in manufacturing cost can be suppressed low.
< grinding treatment >
When a polishing target (target) such as particles or projections is present on the surface 30x of the resin film 30, the target may be polished and planarized by a polishing apparatus. The detection of foreign matter such as particles can be realized by processing an image acquired by an image sensor, for example. After the polishing process, a planarization process may be performed with respect to the surface 30x of the resin film 30. The planarization treatment includes a step of forming a film with improved planarity (planarization film) on the surface 30x of the resin film 30. The planarization film need not 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 include a silicon oxide film, a silicon nitride film, and the like. 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. In order to distinguish this gas barrier film from a gas barrier film described later that covers the functional layer region 20, it may also be referred to as a "lower layer gas barrier film". In addition, canThe gas barrier film covering the functional layer region 20 is referred to as an "upper layer gas barrier film". The lower gas barrier film may be made of, for example, Si3N4And (4) forming. Si3N4Has a linear expansion coefficient of about 3 ppm/K. According to some embodiments of the present disclosure, the coefficient of thermal expansion of the release layer 12 is between the coefficient of linear expansion of the base 10 and the coefficient of linear expansion of the resin film 30, which can be avoided by Si3N4The crack is generated on the formed lower gas barrier layer.
< functional layer area >
Next, a process of forming the functional layer region 20 including the TFT layer 20A, the OLED layer 20B, and the like, and forming 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 the susceptor 10. The release layer 12 and the resin film 30 adhered on the base 10 are located between the base 10 and the functional layer region 20.
In more detail, 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 circuit that implements a TFT array of an active matrix. OLED layer 20B includes an array of OLED elements that can each be independently driven. 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. The 1 pixel of the display may be constituted by sub-pixels of different colors, e.g. R (red), G (green), B (blue). The example shown in fig. 4 includes 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 line DL is a wiring for transmitting a data signal for specifying a video 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 carrying a signal for controlling on/off of the selection TFT element Tr 1. The driving TFT element Tr2 controls the conduction state between the power 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 if the selection TFT element Tr1 is turned off, the on state of the drive TFT element Tr2 is maintained by the storage capacitor CH.
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".
A part of the circuit elements and the wirings shown in fig. 4 may be included in any one 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, 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 have a bottom gate type or a top gate type. In addition, the light emission of the OLED element included in the OLED layer 20B may be a bottom emission type or a top emission type. The specific configuration of the OLED element is also arbitrary.
Materials constituting the semiconductor layer of the TFT element include, 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 process of forming the TFT layer 20A includes a heat treatment process 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 layer gas barrier film 40 is a multilayer film in which an inorganic material layer and an organic material layer are laminated. Further, elements such as an adhesive film, other functional layers constituting the touch panel, and a polarizing film may be disposed between the upper gas barrier film 40 and the functional layer region 20, or further on the upper gas barrier film 40. The formation of the upper gas barrier film 40 can be performed by a Thin Film Encapsulation (TFE) technique. From the viewpoint of sealing reliability, the film is denseThe WVTR (Water Vapor Transmission Rate) of the seal structure typically requires 1 × 10-4g/m2And/day is less. This benchmark is reached according to embodiments of the present disclosure. 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. The 1 stacked structure 100 includes a plurality of OLED devices 1000 supported by a base 10. In the example shown in fig. 5, 1 laminated structure 100 includes more functional layer regions 20 than the example shown in fig. 1A. As described above, the number of functional layer regions 20 supported by 1 susceptor 10 is arbitrary.
< protective sheet >
Reference is next made to fig. 3D. As shown in fig. 3D, a protective sheet 50 is stuck to the upper surface of the laminated structure 100. The protective sheet 50 may be formed of a material such as polyethylene terephthalate (PET), polyvinyl chloride (PVC), and the like. As described above, the typical example of the protective sheet 50 has a laminated structure having a coating layer with a release agent on the surface. The thickness of the protective sheet 50 may be, for example, 50 μm or more and 150 μm or less.
After the laminated structure 100 manufactured in this way is prepared, the manufacturing method based on the present disclosure can be performed using the manufacturing apparatus (the peeling apparatus 220) described above.
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 cover the entire resin film 30 and spread outward of the resin film 30. Alternatively, the protective sheet 50 may cover the entire resin film 30 and spread outward from the base 10. As described later, after the base 10 is separated from the laminated structure 100, the laminated structure 100 becomes a flexible sheet-like structure having no rigidity. The protective sheet 50 plays a role of protecting the functional layer region 20 from collision, friction, and the like when the functional layer region 20 collides with or comes into contact with an external device, appliance, or the like in the step of peeling the base 10 and the step after peeling. Since the protective sheet 50 is finally peeled off from the laminated structure 100, a typical example of the protective sheet 50 has a laminated structure having an adhesive layer (coating layer of release agent) with a small adhesive force on the surface. A more detailed description of the laminated structure 100 is set forth later.
< cutting of OLED device >
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 cutting each of the intermediate region 30i of the resin film 30 and the plurality of flexible substrate regions 30d is performed. The cutting step is not necessarily performed before the LLO step, and may be performed after the LLO step.
The cutting can be performed by cutting the central portion of the adjacent OLED devices with a laser beam or a dicing saw. In the present embodiment, the portion of the laminated structure other than the base 10 is cut, and the base 10 is not cut. However, the base 10 may be cut to obtain a partially laminated structure including the respective OLED devices and the base portion supporting the respective OLED devices.
Hereinafter, a step of cutting the laminated structure other than the susceptor 10 by irradiation with a laser beam will be described. The irradiation position of the laser beam for cutting 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 of the cut resin film 30 and each of the plurality of flexible substrate regions 30d, respectively. The irradiation position of the laser beam for cutting is along the outer periphery of each flexible substrate region 30 d. In fig. 6A and 6B, the irradiation position (cutting position) CT indicated by an arrow or a broken line is irradiated with a laser beam for cutting, thereby cutting the portion of the laminated structure 100 other than the base 10 into a plurality of OLED devices 1000 and other unnecessary portions. By the cutting, a gap of several tens μm to several hundreds μm is formed between each OLED device 1000 and its periphery. As described above, such cutting may be performed by a dicing saw instead of the irradiation of the laser beam. After cutting, the OLED device 1000 and other unwanted parts are also bonded to the base 10.
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 "unnecessary portion" is a continuous 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 cutting laser beam may be set so that the "unnecessary portion" is divided into a plurality of portions. The sheet-like structure as the "unnecessary portion" includes not only the intermediate region 30i of the resin film 30 but also a cut portion of the laminate (for example, the gas barrier film 40 and the protective sheet 50) existing on the intermediate region 30 i.
In the case of cutting with a laser beam, the wavelength of the laser beam may be in any one of the infrared, visible, and ultraviolet regions. From the viewpoint of reducing the influence of the cut-off of the pedestal 10, a laser beam having a wavelength included in the green to ultraviolet regions is preferable. For example, according to Nd: YAG laser devices can perform cutting by using the second harmonic (wavelength 532nm) or the third harmonic (wavelength 343nm or 355 nm). In this case, if the laser output is adjusted to 1 to 3 watts and scanned at a speed of about 500mm per second, the laminate supported by the base 10 can be cut (diced) into the OLED device and unnecessary portions without damaging the base 10.
According to the embodiment of the present disclosure, the cutting is performed at an earlier timing than in the prior art. Since the cutting is performed in a state where the resin film 30 is bonded to the base 10, even if the interval between the adjacent OLED devices 1000 is narrow, the cut alignment can be performed with high accuracy and high precision. Therefore, the interval between adjacent OLED devices 1000 can be shortened, thereby reducing the finally unnecessary wasted portion.
< peeling light irradiation >
Fig. 7A is a diagram schematically showing a state immediately before the stage 212 supports the laminated structure 100 in a manufacturing apparatus (peeling apparatus) not shown. The table 212 in the present embodiment is an adsorption table having a plurality of holes on the surface for adsorption. 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 table 212. The arrangement relationship between the stage 212 and the laminated structure 100 is not limited to the illustrated example. For example, the upper and lower sides of the stacked structure 100 may be reversed, and the stage 212 may be 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 the side of the base 10 by the peeling light 216 shaped like a line extending in a direction perpendicular to the paper surface of the figure. The release layer 12 absorbs the ultraviolet laser light and is heated in a short time. A part of the resin film 30 is vaporized or decomposed (disappeared) at the interface between the release layer 12 and the resin film 30 by 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, in other words, the support substrate 200 is reduced. The wavelength of the stripping light 216 is typically in the ultraviolet region. The light absorption of the susceptor 10 is about 10% in a region with a wavelength of 343 to 355nm, for example, but can 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 peeling apparatus in the present embodiment includes a line beam light source that emits peeling light 216. The line beam light source includes a laser device and an optical system for shaping a laser beam emitted from the laser device into a line beam shape.
Fig. 8A is a perspective view schematically showing a state in which the laminated structure 100 is irradiated with a line beam (peeling light 216) emitted from the line beam light source 214 of the peeling device 220. For ease of understanding, the stage 212, the laminated structural body 100, and the line beam light source 214 are illustrated in a state of being separated in the Z-axis direction of the drawing. When the peeling light 216 is irradiated, the second surface 100b of the laminated structure 100 is in contact with the stage 212.
Fig. 8B schematically shows the position of the stage 212 when the peeling light 216 is irradiated. Although not shown in fig. 8B, the stacked structural body 100 is supported by the stage 212.
Examples of laser devices that emit the stripping light 216 include gas laser devices such as excimer lasers, solid-state laser devices such as YAG lasers, semiconductor laser devices, and other laser devices. The excimer laser device of the XeCl can obtain laser with the wavelength of 308 nm. When neodymium (Nd) -doped yttrium vanadate (YVO4) or ytterbium (Yb) -doped YVO4 is used as the laser oscillation medium, the wavelength of the laser beam (fundamental wave) emitted from the laser oscillation medium is about 1000nm, and therefore, the laser beam can be converted into a laser beam (third harmonic wave) having a wavelength of 340 to 360nm by the wavelength conversion element and used.
From the viewpoint of suppressing the generation of soot, it is more effective to use a laser beam having a wavelength of 308nm generated by an excimer laser device than a laser beam having a wavelength of 340 to 360 nm. Further, 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, for example, 50 to 400mJ/cm2Is performed at the energy irradiation density of (1). By using the release layer made of an alloy of aluminum and silicon having a high thermal conductivity, the lower limit of the energy irradiation density can be increased. The linear beam-shaped stripping light 216 has a size traversing the susceptor 10, that is, a linear length (long axis size, Y axis direction size in fig. 8B) exceeding the length of one side of the susceptor. The wire length may be, for example, 750mm or more. On the other hand, the line width (minor axis dimension, X-axis dimension in fig. 8B) of the stripping light 216 may be, for example, about 0.2 mm. These dimensions are the size of the irradiated area in the interface of the resin film 30 and the susceptor 10. The stripping light 216 may be irradiated as a pulse or continuous wave. The pulsed irradiation may be performed at a frequency of, for example, about 200 times per second.
The irradiation position of the peeling light 216 is relatively moved with respect to the base 10, and scanning of the peeling light 216 is performed. The light source 214 that emits the peeling light and an optical device (not shown) are fixed in the peeling device 220, and the laminated structure 100 may or may not be moved. 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.
< peeling >
Fig. 9A shows a state in which the stacked structure 100 is in contact with the stage 212 after irradiation with the peeling light. In maintaining this state, the distance from the stage 212 to the base 10 is enlarged. At this time, the stage 212 in the present embodiment adsorbs the OLED device portion of the laminated structure 100.
The peeling (peeling) is performed by holding the base 10 by a driving device (not shown) and moving the entire base 10 in the arrow direction. The susceptor 10 can move together with the suction table in a state of being sucked by the suction table not shown. The direction of movement of the base 10 need not be perpendicular to the first surface 100a of the laminated structure 100, but may be inclined. The movement of the base 10 need not be a linear movement but may be a rotational movement. The base 10 may be fixed by a not-shown holding device or another table, 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 laminated structural body 100 thus separated. The first portion 110 of the stacked structural body 100 includes a plurality of OLED devices 1000 in contact with the stage 212. Each OLED device 1000 has a functional layer region 20 and a plurality of flexible substrate regions 30d of a resin film 30. In contrast, the second portion 120 of the laminated structure 100 has the base 10 and the release layer 12.
The individual OLED devices 1000 supported by the table 212 are in a cut-off relationship with each other and, therefore, can be easily removed from the table 212 simultaneously or sequentially.
In the above-described embodiment, the OLED devices 1000 are cut and separated before the LLO process, but the OLED devices 1000 may be cut and separated after the LLO process. Further, the severing separation of each OLED device 1000 may include cutting the submount 10 into corresponding portions.
According to the embodiments of the present disclosure, even when a flexible film formed of polyimide and PET having high transparency to transmit ultraviolet rays is used or a flexible film having low transparency but being thin (having a thickness of 5 to 20 μm) and capable of transmitting ultraviolet rays is used, deterioration of the characteristics of the functional layer region and deterioration of the performance of the gas barrier layer due to ultraviolet rays can be suppressed. Further, since aluminum alloy is easily recovered and reused unlike high melting point metals, an increase in manufacturing cost with the release layer can also be suppressed to be low.
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, tablet personal computer terminals, vehicle-mounted displays and medium-sized or even large-sized television devices.
Description of the reference numerals
10: base, 12: release layer, 20: functional layer area, 20A: TFT layer, 20B: OLED layer, 30: resin film, 30 d: flexible substrate region of resin film, 30 i: middle region of resin film, 40: gas barrier film, 50: protective sheet, 100: laminated structure, 212: table, 1000: an OLED device.
