阅读说明：本技术 基板的接合方法、透明基板层叠体和具备基板层叠体的器件 (Substrate bonding method, transparent substrate laminate, and device provided with substrate laminate ) 是由 须贺唯知 松本好家 于 2018-12-21 设计创作，主要内容包括：基板的接合方法具备：在至少一个为透明基板的一对基板中的两个或任意一个的接合表面上形成金属氧化物的薄膜的步骤；和经由金属氧化物的薄膜使一对基板的接合面相互接触的步骤。(The method for bonding substrates includes: a step of forming a thin film of a metal oxide on a bonding surface of either or both of a pair of substrates at least one of which is a transparent substrate; and a step of bringing the bonding surfaces of the pair of substrates into contact with each other via a thin film of a metal oxide.)

1. A method for bonding substrates, comprising:

a step of forming a thin film of a metal oxide on a bonding surface of either or both of a pair of substrates at least one of which is a transparent substrate; and

and bringing the bonding surfaces of the pair of substrates into contact with each other through the thin film of the metal oxide.

2. The method for bonding substrates according to claim 1, wherein the step of forming a thin film of a metal oxide on the bonding surface is performed by an ion beam sputtering method.

3. The bonding method of a substrate according to claim 1 or 2, wherein the step of forming a thin film of a metal oxide on the bonding surface of the substrate comprises: the film is formed by a sputtering method using a metal as a target and in a mixed gas consisting essentially of an inert gas and oxygen.

4. The method for bonding substrates according to claim 1, wherein the step of forming a thin film of a metal oxide on the bonding surface is performed by an ALD method.

5. The method for bonding substrates according to any one of claims 1 to 4, further comprising a step of irradiating the bonding surface of the substrate with energetic particles before the step of forming a thin film of a metal oxide on the bonding surface.

6. The method for bonding substrates according to any one of claims 1 to 5, further comprising a step of irradiating energetic particles to a surface of the thin film of the metal oxide.

7. The method for bonding substrates according to any one of claims 1 to 6, wherein the step of irradiating the surface of the thin film of metal oxide with energetic particles comprises: energy particles of a mixed gas substantially composed of an inert gas and oxygen are irradiated.

8. A method for bonding substrates according to any one of claims 1 to 7, wherein at least from the step of forming the thin film of the metal oxide to the step of bringing the bonding surfaces into contact with each other, the step is performed in vacuum.

9. A method of bonding substrates according to any one of claims 1 to 8, further comprising a step of performing a heat treatment after the step of bonding the substrates.

10. The method for bonding substrates according to claim 9, wherein the heat treatment is performed at 200 ℃ or lower.

11. The method for bonding substrates according to any one of claims 1 to 10, wherein two or any one of the substrates to be bonded is a transparent glass substrate.

12. The method of bonding substrates according to any one of claims 1 to 10, wherein one of the substrates to be bonded is a transparent glass substrate, and the other substrate is a substrate including an optical element.

13. The method for bonding substrates according to any one of claims 1 to 10, wherein a bonding surface of at least one of the substrates to be bonded is substantially made of a polymer material.

14. A device comprising a substrate laminate formed by the method for bonding substrates according to any one of claims 1 to 13.

15. A device is provided with a substrate laminate substantially composed of a transparent substrate, a substrate including an optical element, and a metal oxide interposed between the transparent substrate and the substrate including the optical element,

the light transmittance of the substrate laminate that passes through the transparent substrate and faces the optical element is 97% or more of the light transmittance that passes through the transparent substrate and faces the optical element when the transparent substrate and the substrate including the optical element are laminated.

16. A transparent substrate laminate substantially composed of a first transparent substrate, a second transparent substrate, and a metal oxide interposed between the first transparent substrate and the second transparent substrate,

the transparent substrate laminate has a light transmittance of 97% or more of a light transmittance when a pair of transparent substrates are laminated.

17. A device comprising the transparent substrate laminate according to claim 16.

Technical Field

The present invention relates to a method of bonding substrates. More specifically, the present invention relates to a method of forming a laminate of transparent substrates so that the laminate can substantially enjoy the light transmittance of the laminate itself.

Background

As a method for bonding substrates, a method is known in which a surface of a substrate is irradiated with energetic particles to activate the surface and bond the substrate. One of the methods is a method called room temperature bonding. Substrate bonding techniques using such surface activation treatments are currently used in a wide variety of applications. As a non-limiting example, the present invention may be used in a laminate formation where a process at a high temperature is not suitable or desired to be avoided in the whole or a part of a bonding process. For example, the present invention is sometimes used for bonding substrates of different materials, bonding substrates of materials that are not likely to cause atomic diffusion except at high temperatures, and the like.

Disclosure of Invention

Problems to be solved by the invention

The present invention includes a method for bonding substrates, including: a step of forming a thin film of a metal oxide on a bonding surface of either or both of a pair of substrates at least one of which is a transparent substrate; and a step of bonding the bonding surfaces of the substrates in contact with each other via a thin film of a metal oxide.

Drawings

Fig. 1 is a diagram illustrating the respective steps of a method for forming a laminate according to an embodiment together with an apparatus configuration.

Fig. 2 is a graph showing light transmittance and bonding strength as experimental results in the examples.

Fig. 3 is a schematic cross-sectional view showing steps of a method for forming a laminate according to another embodiment.

Detailed Description

As an example of a device using a transparent substrate, many optoelectronic devices represented by a display (display element) have a structure in which a light emitting element is attached to glass, which is a light extraction member. Here, the two are generally bonded together via an adhesive film. By way of example and not limitation, an organic electroluminescent (hereinafter also referred to as "organic EL") device is configured by attaching an organic EL element covered with a polymer to a cover glass. In flexible organic EL, an organic EL element is also covered with a polymer, and a polarizing plate and the like are also formed of a polymer.

However, there is no technique for directly bonding a polymer substrate or a polymer film to a cover glass having a function of protecting a device such as an organic EL element. Therefore, the device and the cover glass are indirectly attached via an optically transmissive adhesive sheet (hereinafter also referred to as "OCA"). Here, components such as OCA become cost factors. Further, the products using OCA are not suitable for applications in situations where organic substances cannot be used, such as under radiation.

In the field of displays (display devices), there is a great demand for bonding glass plates to each other without impairing light transmittance. Generally, the glasses are formed using an adhesive formed of an organic material. However, the adhesive is considered to be one cause of deterioration in light transmittance. Further, since the adhesive is formed by applying an organic material, bubbles are likely to be generated at the bonding interface, which affects the quality of the bonding interface.

Therefore, it is conceivable to bond a light-emitting element covered with a polymer to glass having high transparency by a direct bonding method such as room temperature bonding. However, SiO, which is considered to be a main component of glass₂It is difficult to bond the substrates by irradiation with energetic particles.

The method for bonding substrates according to the present invention includes: a step of forming a thin film of a metal oxide on a bonding surface of either or both of a pair of substrates at least one of which is a transparent substrate; and a step of bringing the bonding surfaces of the pair of substrates into contact with each other via a thin film of a metal oxide. The metal oxide is transparent to visible light, and the bonding force of the metal oxide formed by, for example, a sputtering method or the like is strong. Therefore, both permeability and adhesiveness are achieved.

< substrates to be bonded >

The "transparent substrate" refers to a substrate having high transmittance of light including visible light. For example, the visible light transmittance may be 90% or more. The "transparent substrate" may be formed to contain SiO₂Glass, tempered glass, polymer, etc. as a base material or containing SiO₂A substrate of glass, tempered glass, polymer, or the like. The method of bonding substrates included in the present invention has many advantages, and as one of the advantages, a method including SiO that cannot be bonded without impairing or greatly reducing the permeability has been hitherto included₂The substrate of (2) can also be bonded while maintaining high light transmittance.

One or both of the substrates attached on the transparent substrate may be transparent substrates. The substrates to be bonded may be a pair of substrates, a pair of transparent substrates, or a transparent substrate and a translucent or opaque substrate.

Both of the pair of substrates to be bonded may be glass substrates or polymer substrates. One of the pair of substrates to be bonded may be a glass substrate and the other may be a polymer substrate. The polymer substrate may be a substrate substantially made of a polymer material. At least one of the substrates to be bonded may have a bonding surface substantially made of a polymer material.

The method of bonding substrates may include providing a substrate or a transparent substrate and other substrates used in bonding, and may further include providing a pair of substrates at least one of which is a transparent substrate.

One or both of the substrates to be bonded may be a substrate mainly composed of a polymer material or a polymer substrate. The polymer material substrate may be a plastic substrate or a flexible substrate. The polymer material may be PEN (polyethylene naphthalate), PET (polyethylene terephthalate), another polyester material, PI (polyimide), COP (cycloolefin polymer), or PC (polycarbonate), but is not limited thereto, and may be another polymer or a plastic material. The substrate may comprise POL (polarizing film). The substrate may be substantially composed of a polymer material, may contain a polymer material, or may be composed of a polymer material and another material or member. The polymer substrate may be a transparent substrate.

The substrate to be bonded may be circular or rectangular, or may be in the shape of a tape (tape).

One of the substrates to be bonded may contain an optical element. The optical element may be a light-emitting element or a light-receiving element, may include both of them, or may include other optical, optoelectronic, or electronic elements, circuits, or materials. The substrate to be bonded may include a layer of the optical element, or may include a layer of the optical element and a layer of a polymer. For example, the substrate may be configured to include a layer including an optical element or an optical element layer, and a layer including a polymer material or a polymer layer.

One of the substrates to be bonded may include an optical element layer including an optical element and a polymer layer including a polymer material covering the optical element layer. The surface of the polymer layer may be a bonding surface.

In the final product, for example, when the optical element is a light-emitting element, all the substrates and layers through which light emitted from the light-emitting element to the outside of the product passes are preferably transparent, and when the optical element is a light-receiving element, for example, all the substrates and layers through which light incident from the outside of the product passes to reach the light-receiving element are preferably transparent. In the case of a final product including an optical element, the term "transparent" means transparent to the extent that a light beam of a practical amount is extracted to the outside from among light beams emitted from a light emitting element, or to the extent that a light beam of a practical amount is detected by a light receiving element from among light beams incident from the outside.

On the other hand, the transmittance of light of the transparent substrate laminate formed after bonding (hereinafter referred to as "post-bonding transmittance") is preferably sufficient for the use of the final product. For example, the post-bonding transmittance is preferably 90% or more of the transmittance of all two or more substrates in which the substrates in the pre-bonding state are directly stacked (hereinafter referred to as "pre-bonding transmittance"). The light transmittance after bonding may be 95% or more of the light transmittance before bonding. The light transmittance after bonding may be 97% or more, 98% or more, or 99% or more of the light transmittance before bonding.

< Metal oxide >

The metal of the metal oxide may be selected from alkali metals as typical metals: li, Na, K, Rb, Cs or alkaline earth metal: ca. Sr, Ba, Ra, Mg group elements: be. Mg, Zn, Cd, Hg, aluminum group elements: al, Ga, In, rare earth elements: y, La, Ce, Pr, Nd, Sm, Eu, tin group elements: ti, Zr, Sn, Hf, Pb, Th, iron group elements: fe. Co, Ni, earth-acid element (earth-acid): v, Nb, Ta, chromium group elements: cr, Mo, W, U, manganese group elements: mn, Re, noble metals: cu, Ag, Au, platinum group elements: ru, Rh, Pd, Os, Ir, Pt. The metal may be composed of one metal, may contain two or more metals, or may be an alloy. The metal may be Si or so-called metal silicon. The metal may be a metal other than silicon.

The metal oxide may be a metal oxide having a stoichiometric composition in one embodiment, may be a non-stoichiometric composition in another embodiment, and may have a larger or smaller amount of metal than oxygen, for example. The metal oxide may be a mixture of metal and oxygen, and the combination of metal and oxygen may be different from that of the metal oxide having a stoichiometric composition, or may contain a combination of different metals and oxygen.

< formation of Metal oxide film >

The step of forming a thin film of a metal oxide on the bonding surface of the substrate may be performed by a plasma CVD method, a sputtering method, an evaporation method, an ALD (atomic layer deposition) method, a (reactive ion etching) RIE method. However, the step of forming the thin film of the metal oxide is not limited to these methods, and may be performed by other methods.

The step of forming a thin film of a metal oxide on the bonding surface of the substrate may be performed by a sputtering method, or may be performed by a method or a process including a sputtering method. The sputtering method may be an ion beam sputtering method or an ion beam assisted sputtering method. It is considered that the metal oxide formed by the ion beam sputtering method has low crystallinity, relatively many crystal defects, relatively many surfaces exposed by the atom Bell, and a large number of so-called dangling bonds. Therefore, it is considered that the surface is activated with a relatively high activity, and the bonding becomes easy. However, this physical examination is an inference and the present invention is not limited to this mechanism.

In one embodiment, the step of forming a thin film of a metal oxide on the bonding surface of the substrate may be performed by an ion beam assisted sputtering method. The method can comprise the following steps: a metal oxide is formed on a target substrate by a sputtering method using a metal as a target and in a mixed gas substantially composed of an inert gas and an oxygen gas. In another embodiment, the sputtering method may be performed in a mixed gas consisting essentially of nitrogen and oxygen, with a metal as a target. By irradiating the metal target with the mixed gas and sputtering the metal, a mixture of the metal and oxygen, or an oxide of the metal, or a metal oxide can be formed on the bonding surface.

In another embodiment, the step of forming a thin film of metal oxide on the bonding surface of the substrate may include: sputtering is performed with a metal as a target in a direction of a bonding surface substantially by an inert gas, and oxygen is fed to the bonding surface from other directions.

The inert gas may be a rare gas. The rare gas may be any one of helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn), or a mixed gas of two or more of these gases. The inert gas may be argon (Ar), in particular.

The metal used in the sputtered target can be aluminum (Al). Al can be formed by sputtering an aluminum target with a mixed gas of a rare gas such as argon and oxygen₂O₃And the like.

The oxide of aluminum in the thin film may be a stoichiometric composition of Al₂O₃It may be comprised in a non-stoichiometric ratio, or may be a mixture thereof. In the formed metal oxide, the combination form of aluminum and oxygen can be combined with the stoichiometric ratio to form Al₂O₃The aluminum (b) may contain different combinations of aluminum and oxygen.

The step of forming a thin film of metal oxide on the bonding surface of the substrate may include: the target is sputtered with a metal oxide as a target, whereby the metal oxide is formed on the target substrate. As a non-limiting example, the metal oxide as the target can be alumina (Al)₂O₃). The gas used for sputtering may be a rare gas or nitrogen gas, or a mixture thereof, or a gas containing a rare gas or nitrogen gas and another gas.

The mixed gas used in sputtering may be substantially composed of argon and oxygen. The flow rate of the oxygen contained in the mixed gas may be substantially 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10% or any value or more or a value larger than this with respect to the flow rate or the total flow rate of the mixed gas.

The mixed gas may contain argon gas, or may contain a rare gas other than argon gas. When the mixed gas contains a gas different from argon gas, or when the sputtering characteristics are substantially different or significantly different due to the influence of the apparatus, the environment, or the like, an appropriate flow rate of oxygen gas can be selected. For example, when the sputtering rate of the rare gas is smaller than that in the case of using only argon gas, the flow rate of oxygen may be less than 5%, for example, 4% or less, or 3% or less. In contrast, for example, when the sputtering rate of the rare gas is larger than that in the case of using only argon gas, the flow rate of oxygen may be more than 5%, for example, 6%, 7% or more.

The substrates to be bonded may be glass substrates and glass substrates, glass substrates and polymer material (polymer) substrates, polymer substrates and polymer substrates. When bonding glass to a bonding surface of glass or bonding polymer to a bonding surface of polymer, a metal oxide film may be formed on either or both of them. When a metal oxide film is formed on any one of the bonding surfaces of glass and polymer, the metal oxide film can be formed on the polymer, and thus the bonding strength can be often improved.

The thickness of the metal oxide film to be formed may be about 0.1nm to about 10nm, and may be at least or more than the value of 0.1nm, 0.2nm, 0.3nm, 0.4nm, 0.5nm, 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, or 9 nm. The thickness of the metal oxide film formed may be 10nm or less, or may be 9nm, 8nm, 7nm, 6nm, 5nm, 4nm, 3nm, 2nm or 1nm or less. The thickness of the layer of metal oxide in the substrate stack formed by bonding may be from about 0.1nm to about 20 nm.

< surface activation treatment >

The surface activation treatment may include a step of irradiating the surface of the oxide of the metal with energetic particles.

The energetic particles may be generated by accelerating ions or neutral atoms of used gas particles or atoms or a mixed gas thereof using a particle beam source such as an ion beam source or a Fast Atomic Beam (FAB) source. The irradiation of the energetic particles may be performed using a plasma source.

The particle beam source may be used to impart a predetermined kinetic energy to the particles, for example at a pressure of 1 × 10^-5Pa (pascal) or less. In order to draw a higher vacuum, use is made ofThe vacuum pump is operated to efficiently discharge the substances removed from the surface of the metal region to the outside of the atmosphere. This can suppress adhesion of an undesirable substance to the exposed new surface. Further, the particle beam source can apply a high acceleration voltage, and therefore, can impart high kinetic energy to the particles. Therefore, it is considered that the removal of the surface layer and the activation of the new surface can be efficiently performed.

As the neutral Atom Beam source, a Fast Atom Beam source (FAB) may be used. Typically, a fast atomic beam source (FAB) has the following composition: a plasma of a gas is generated, an electric field is applied to the plasma, and positive ions of particles ionized from the plasma are extracted and neutralized by passing through an electron cloud. In this case, for example, in the case of argon (Ar) as a rare gas, the supply power to the fast atom beam source (FAB) may be set to 1.5kV (kilovolt) or 15mA (milliamp), or may be set to a value between 0.1 and 500W (watt). For example, when a fast atomic beam source (FAB) is operated at 100W (watt) to 200W (watt) and irradiated with a fast atomic beam of argon (Ar) for about 2 minutes, the oxide, contaminant, and the like (surface layer) on the surfaces to be bonded are removed, and the new surfaces can be exposed.

As the ion beam source, a cold cathode type ion source may be used.

The ion beam source may be a line type cold cathode type ion beam source. The linear particle beam source is a particle beam source having a linear (linear) or elongated particle beam radiation opening from which a particle beam can be emitted linearly (linearly). The length of the radiation opening is preferably larger than the diameter of the substrate to which the particle beam is irradiated. When the substrate is not circular, the length of the radiation port is preferably larger than the maximum dimension in the direction in which the radiation port of the substrate relatively moved with respect to the particle beam source extends.

The particle beam emitted from the linear particle beam source irradiates a linear region or an elongated region on the substrate at a certain time in the surface activation process. Then, a particle beam is emitted from the linear particle beam source toward the substrate, and the substrate support is scanned in a direction perpendicular to a direction in which the radiation port extends. As a result, the irradiation region of the linear particle beam passes through all the joints of the substrates. When the linear particle beam source passes over the substrate, the entire substrate is substantially uniformly irradiated with the particle beam, and surface activation occurs.

A linear particle beam source is suitable when the surface of a substrate having a large area is irradiated relatively uniformly with a particle beam. In addition, the linear particle beam source can relatively uniformly irradiate particle beams corresponding to various shapes of the substrate.

The energetic particles may be a mixed gas substantially composed of a rare gas and oxygen, may be the mixed gas, or may contain other gases. When an energetic particle beam using only a rare gas without oxygen is irradiated, oxygen may be deficient in metal in the vicinity of the surface of the metal oxide. In this case, the amount of metal is relatively increased, and thus the transmittance of light such as visible light may be reduced. Presumably this is due to absorption in regions containing relatively much of this metal. Therefore, it is considered that the lack of oxygen can be avoided or reduced by including oxygen in the energy particle beam irradiated to the joining surface, and bonding the oxygen to the surface of the metal oxide. It is considered that sufficient light transmittance of the laminated body of the bonded transparent substrates can be obtained thereby.

The energetic particles may be or may contain a rare gas. The rare gas may be argon or other rare gas. The energy particles may be neutral atoms or ions, radical species, or a particle group in which these are mixed.

The term "surface activation" refers to a treatment or process for surfaces that are not substantially bonded or joined without contact, and refers to a treatment or the like for obtaining a desired or substantially effective bond when the surfaces after the treatment or the like are brought into contact with each other. The laminate formed by bonding the substrates after the surface activation treatment may be directly subjected to heating, light treatment, or the like, or may not be subjected to any treatment.

The removal rate of the surface layer may vary depending on the operating conditions of the respective plasma or beam source or the kinetic energy of the particles. Therefore, it is necessary to adjust various conditions including the treatment time of the surface activation treatment. For example, a surface analysis method such as Auger Electron Spectroscopy (AES) or X-ray photoelectron Spectroscopy (XPS) may be used, and a time period during which the presence of oxygen or carbon contained in the surface layer cannot be confirmed or a time period longer than this time period may be used as the treatment time of the surface activation treatment.

< bonding >

Bonding may include bringing the bonding surfaces of the substrates into contact with each other via the surface-activated thin film of metal oxide. The force may be applied to the substrate from the side of the substrate opposite to the bonding surface or the surface other than the bonding surface when they are brought into contact. For example, a force in a vertical direction may be applied to the bonding surface from the outside of the substrate. In one embodiment, the pressurization may apply a force such that substantially uniform force is achieved across the entire contacted joint surfaces. In another embodiment, the pressurization may be performed to different surfaces of the bonded surface after the contact at each time. The intensity of the force during pressurization may be constant or variable in time. The pressing may be performed at different times for each part of the joint surface. The pressing device may be moved by sliding with respect to the substrate in contact with the substrate to sequentially press the bonding surfaces. The pressing device may have a roller-shaped pressing portion.

In the method for bonding substrates included in the present invention, the step of forming a metal oxide layer on the bonding surface of the substrates may be performed in a vacuum or a low-pressure atmosphere at all times or may be performed without breaking the vacuum or the low-pressure atmosphere, until the step of bringing the pair of substrates into contact or bonding the substrates. The atmosphere in vacuum or at low pressure may be at a pressure of 10 deg.f^-16Pa or 10^-16An atmosphere of Pa or less. Alternatively, the substrate may be temporarily removed from the vacuum after the metal oxide layer is formed, in which case, a dummy substrate or the like may be temporarily bonded to the bonding surface to prevent the bonding surface from being exposed to the atmosphere, and after returning to the vacuum again, the dummy substrate may be removed to bring the bonding surfaces into contact with each other in the vacuum. An atmosphere under vacuum or low pressure may include such a case. By performing these processes in vacuum, unwanted substances can be avoidedThe adhesion of the substance to the bonding surface, adsorption, or oxidation and oxidation of the bonding surface with hydrogen oxidation efficiently activates the surface, and the degree of activation of the surface after activation can be maintained or the reduction thereof can be suppressed as much as possible, thereby avoiding or reducing the occurrence of non-bonded portions.

< Heat treatment >

The method for bonding substrates included in the present invention may further include a step of heating the laminate after bonding. The heating temperature may be 100 ℃ or higher, 200 ℃ or higher, or 210 ℃ or lower, or 220 ℃ or lower. The temperature of heating may be 100 ℃ or 150 ℃ or higher than the above value. The heating temperature may be 400 deg.C, 300 deg.C, 250 deg.C, 225 deg.C, 220 deg.C, 210 deg.C, 200 deg.C or 150 deg.C or lower. The heating temperature may be substantially 100 ℃, 150 ℃, 200 ℃. The heating may be performed simultaneously for the entire substrate or for each part of the substrate.

The step of forming a metal oxide layer on the bonding surface, the step of performing activation treatment, and the step of bonding the pair of substrates may be performed substantially at the bonding interface temperature of 100 ℃ or less or at 200 ℃ or intentionally avoiding heating treatment.

< treatment for activating substrate surface before film formation >

The method for bonding substrates included in the present invention may further include a step of irradiating the bonding surface of the substrate with energetic particles before film formation. By activating the bonding surface of the substrate by irradiation with the energetic particles, the bonding strength between the bonding surface and the thin film formed thereon can be improved.

< example 1>

The glass substrates were bonded by the method of the present invention, and the light transmittance and bonding strength were evaluated.

The bonding apparatus 100 shown in fig. 1(a) includes a vacuum chamber 101, a substrate support 104 disposed inside the vacuum chamber 101 and movably supporting a first substrate 102 and a second substrate 103, a particle beam source 105 as a surface activation processing apparatus, a metal target 106 for forming a thin film of a metal oxide, a rotation axis 104A of the substrate support 104 as a bonding apparatus, and a pressurizing apparatus (not shown). According to this configuration, a good metal oxide can be formed on the substrates 102 and 103 in vacuum, and further, surface activation treatment and substrate bonding (bonding) can be performed without breaking the vacuum, so that a bonding interface having high strength and few defects can be formed.

As shown in fig. 1 a, a vacuum pump (not shown) is connected to the vacuum container 101, and the vacuum degree in the vacuum container 101 can be maintained at 1 × 10^-5A pressure of Pa or less. The particle beam source 105 is rotatable about a rotation axis 105A, and can accelerate a particle group (107) of a mixed gas of argon gas and oxygen gas toward the sputtering target 106 to sputter the metal material. The particle beam source 105 is configured to be able to perform surface activation processing of the substrate surface by emitting a particle beam 105B generated by particles having a predetermined kinetic energy toward the surface of the first substrate 102 or the second substrate 103 in accordance with the position of the substrate support 104. When a metal oxide film is formed only in a predetermined region or a bonding region on the substrate, a mask (not shown) for defining the predetermined region is disposed on the substrate.

In addition, the substrate support 104 is scanned during the deposition of the thin film 107, so that the deposition conditions on the first substrate 102 or the second substrate 103 can be made uniform. The thickness of the metal oxide layer can be controlled in stages by the number of scans with respect to the predetermined operating conditions of the particle beam source 105, the target 106, and the predetermined arrangement positions of the substrates 102 and 103 in the vacuum chamber 101.

In the present embodiment, a glass substrate is used for both the first substrate 102 and the second substrate 103, and more specifically, an alkali-free glass (OA 10-G manufactured by japan electric glass company). The glass substrates 112 and 113 were introduced into a vacuum chamber 101 so that the atmosphere in the chamber was 10 deg.f^-5And a vacuum atmosphere of Pa or less, and the evacuation is continued until the joining is completed with the same evacuation capacity. Metallic aluminum was set as a target 106, a linear cold cathode ion beam source was used as a particle beam source 105, and a mixed gas of argon and oxygen was supplied at a rate of 80sccm in a line of 1.2kV and 400mAAnd driving under the component. Thereby, the target 106 is irradiated with the particle beam 105B of the mixed gas, and the particle group 107 including the mixture of aluminum and oxygen is sputtered toward the bonding surface of the two glass substrates. As a result, thin films of aluminum oxides 107 and 108 are formed on the bonding surfaces of the glass substrates 102 and 103 (fig. 1 (b)). The thickness was about 20 nm. However, in the present invention, the mechanism of sputtering and the state of the sputtering particles 107 from the target 106 to the substrates 102 and 103 are not limited to the above description.

As shown in fig. 1(b), as a surface activation treatment, the particle beam source 105 was rotated around the rotation axis 105A, and fixed at a position facing the first substrate 102 or the second substrate 103, and the surfaces of the aluminum oxide films 107 and 108 formed on the substrates 102 and 103 were irradiated with the energetic particle beam 105C by driving the same particle beam source 105 at a supply rate of 70 seem of argon gas under 1.3kV400 mV. When the surface activation treatment is performed only on a predetermined region on the substrate, a mask (not shown) for defining the predetermined region is disposed on the substrate.

As shown in fig. 1(c), the substrate support 104 includes a rotary shaft 104A as a bonding means provided between portions supporting the first substrate 102 and the second substrate 103. The substrate support 104 is configured to be foldable so that the first substrate 102 and the second substrate 103 are opposed to each other around the rotation axis 104A. Thus, as shown in fig. 1(c), the first substrate 102 and the second substrate 103 can be brought into contact with each other with a simple configuration and the same pressure can be applied uniformly to substantially the entire area. A pressing device (not shown) may be provided to apply a predetermined force from the outside of the folded substrate support 104 so as to press the first substrate 102 and the second substrate 103 against each other at the time of bonding. In this embodiment, the thin films of aluminum oxide formed on the two substrates and subjected to the surface activation treatment are brought into contact with each other. After contact, a force of 5kN was applied perpendicularly to the joint surface for 5 minutes. In addition, a heating device (not shown) may be provided which heats the first substrate 102 and the second substrate 103 at a predetermined temperature in a range in which the functions of the electronic components and the materials of the substrates are not degraded during bonding.

A pressing device (not shown) may be provided to apply a predetermined force from the outside of the folded substrate support 104 so as to press the first substrate 102 and the second substrate 103 against each other at the time of bonding. In addition, a heating device (not shown) may be provided which heats the substrates 102 and 103 and the metal oxides 107 and 108 at a predetermined temperature in a range in which the functions of the electronic components and the materials are not degraded during bonding.

When a target of metallic aluminum is irradiated as a sputtering film formation, the flow ratio of argon gas and oxygen gas in the mixed gas supplied to the ion beam apparatus is changed. FIG. 1 shows that the flow ratio is Ar: O₂Values for transmittance ratio and interface strength at 80: 0 (0%), 77: 3 (3.75%), 76: 4 (5%), 75: 5 (6.25%), 74: 6 (7.5%), 73: 7 (8.75%).

The light transmittance is a visible light transmittance measured by a commercially available visible light transmittance measuring instrument. Generally, the ratio is a ratio before and after the transmission of a light beam in a visible light region or a wavelength region of about 360nm to about 760 nm. In the present invention, the light transmittance measured for the substrates stacked in a state before the laminate forming method is performed is referred to as the pre-bonding light transmittance, and the light transmittance measured for the laminate after the substrate bonding method is performed is referred to as the post-bonding light transmittance. In the present invention, a value obtained by dividing the light transmittance after bonding by the light transmittance before bonding is referred to as a light transmittance ratio. In this example, the light transmittance before bonding was 91.59%.

The strength of the joint interface was measured by the insert insertion method. The insert insertion method is as follows: a blade (blade) is inserted between two substrates after bonding to peel the substrates, and the substrates are peeled from the blade tip to & # 21085; the length of the peeled portion was used for evaluating the bonding strength of wafer bonding, and the interface energy was evaluated as the bonding strength.

Ar: O for sputtering Al target in forming metal oxide film₂The measured values of the light transmittance ratio (black dots) and the bonding strength (white circles) at the flow rate ratio are shown in fig. 2.

With respective Ar: O for sputtering of Al target₂The light transmittance is increased when the flow rate ratio is increased from 0% to 5%, and 99.5% -99% is obtained when the flow rate ratio exceeds 5%Measurement of 9%. I.e., Ar: O₂When the flow rate ratio is 5% or more, an extremely high transmittance ratio of approximately 100% is obtained.

Ar∶O₂The flow rate ratio of 0% means that a thin film of substantially 100% Al is formed. In this case, the metal thin film existing at the substrate bonding interface absorbs visible light, and thus the light transmittance is considered to be relatively low. In contrast, Ar: O₂When the flow rate ratio is increased, aluminum of the target is sputtered together with oxygen, and therefore, it is considered that a mixture of aluminum and oxygen or a thin film of an oxide of aluminum metal is formed as a thin film formed on the substrate bonding surface. Aluminum oxide is a substance transparent to visible light such as sapphire or alumina. It is therefore believed that the resulting mixture of aluminum and oxygen contains a portion of alumina (aluminum oxide). The thin film of alumina may contain a fraction of non-stoichiometric composition at the atomic level. It is therefore considered that the reaction is accompanied by Ar: O₂The flow rate ratio increases, and the proportion of alumina having high transparency to light in the formed thin film increases, thereby improving the transparency of the thin film. Further, Ar: O is considered₂At a flow rate of 5%, the thin film is substantially made of alumina or alumina, and the degree of oxidation is close to saturation. Alternatively, from the following tendency of the bonding strength, it is considered that the light transmittance is almost saturated even if the composition of the film itself does not reach the stoichiometric composition. Thus, it is considered that approximately 100% is reached for visible light. With Ar: O₂The mechanism of the increase and saturation of the light transmittance by the increase of the flow rate ratio is not limited to the above mechanism, and may be other mechanisms.

On the other hand, it was observed that the bonding strength was accompanied by each Ar: O for sputtering of Al target₂The flow rate ratio tends to increase and decrease. Aluminum as a metal is considered to be easily bonded to each other because it is more likely to transfer electrons and is more likely to be deformed at an atomic level than alumina as an oxide. Therefore, it is considered that the bonding strength decreases as the ratio of the metal on the film surface decreases or as the ratio of the oxide on the film surface increases. In this experiment, when the bonding strength was 7.5% or more, a substantially constant value was obtained. This is considered to be because the ratio of the oxide on the surface of the thin filmApproximately saturated or a certain percentage of the effect on the strength of the joint is reached. Between the light transmittance and the bonding strength, an approximately constant value of Ar: O is reached₂The flow rate ratio is different, and this is considered to be because the ratio of the oxide in the thin film becomes insensitive. For example, in this experiment, in Ar: O₂When the flow rate ratio is 5%, the ratio of the oxide in the thin film does not reach the limit, and the metallic aluminum component is present to some extent, but it is considered that the component does not affect the optical characteristics or the effect thereof is negligible at least in the present measurement technique. In the present invention, the above mechanism is considered as an inference, and is not limited to the above mechanism, and may be another mechanism.

The bonding strength also affects the surface roughness of the metal oxide film. In general, when the surface roughness of the metal oxide film is large, the bonding strength is also reduced. Therefore, the absolute value of the experimental result is an actual value, and the tendency can be understood as relative.

< example 2>

The polymer substrates are bonded using the method of the present invention.

As the substrate, a PEN (polyethylene naphthalate) film (テオネツクス manufactured by Dichen corporation) was used&reg; ) And a PI (polyimide) film (カプトン manufactured by DuPont corporation)&reg; ). For each film, the film is heated at a temperature of 70 to 150 ℃ for 1 to 4 hours as a dehydration treatment before the metal oxide film is formed. PEN, PI, PEN and glass substrates, and PI and glass substrates were bonded to each other. An aluminum oxide film was formed on either PEN or PI in the same manner as in example 1. Wherein the flow ratio of argon to oxygen in the mixed gas supplied to the ion beam device is Ar: O₂At 76: 4. On the glass substrate, an aluminum oxide film was not formed. The surfaces to be bonded were subjected to the same surface activation treatment as in example 1, and then the substrates were brought into contact with each other, and a force of 5kN or 10kN was applied for 5 minutes.

The transmittance ratio obtained by dividing the transmittance after bonding by the transmittance before bonding is 97% or more, and is extremely high.

From the experimental results in the present invention, it was also found that a substrate laminate can be formed by the substrate bonding method of the present invention. The present substrate laminate may be a transparent substrate laminate.

The substrate laminate of the present invention may be a transparent substrate laminate including a first substrate, a second substrate, and a layer substantially composed of a metal oxide between the first substrate and the second substrate, wherein the light transmittance of the substrate laminate is 97% or more of the light transmittance when the first substrate and the second substrate are laminated. In another embodiment, the light transmittance of the substrate stack may be 98% or more, 99% or more, 99.1% or more, 99.2% or more, 99.3% or more, 99.4% or more, or 99.5% or more of the light transmittance when the first substrate and the second substrate are stacked.

The substrate laminate of the present invention may be a transparent substrate laminate including a first substrate, a second substrate, and a layer substantially composed of a metal oxide between the first substrate and the second substrate, and having a light transmittance ratio of 97% or more. In another embodiment, the light transmittance may be 98% or more, 99% or more, 99.1% or more, 99.2% or more, 99.3% or more, 99.4% or more, or 99.5% or more.

When a transparent substrate such as a glass substrate is stacked on a substrate including a light-emitting element such as an organic EL element, the following may be used: the light transmittance of the light extracted from the light-emitting element through the glass substrate in the laminate is 97% or more, 98% or more, 99% or more, 99.1% or more, 99.2% or more, 99.3% or more, 99.4% or more, or 99.5% or more, as compared with the light transmittance of the light extracted from the light-emitting element through the glass substrate.

The substrate laminate included in the present invention may have a bonding strength or an interface energy of 0.3J/m²Above, 0.4J/m²Above, 0.5J/m²Above, 1J/m²Above, 1.5J/m²Above or 2J/m²The above.

As previously mentioned, the bond strength may be scaled to the energy of the bonding interface. The bonding strength can be measured as the breaking strength of the bonding interface, or can be determined as the breaking strength of the bonding interface. The blade insertion method is easily applicable to a case where the bonded substrate is a substrate made of a material which is strong to some extent and is not easily plastically deformed, such as a semiconductor wafer or a glass substrate. On the other hand, in the case of a substrate formed of a polymer material, the bonding strength can be measured by a peel test. The breaking strength can be measured by a peel test, and the bonding strength is evaluated. In the peeling method, the bonding strength may be 0.5N/cm or more.

The transparent substrate laminate included in the present invention is composed of only an inorganic material without containing an organic material such as OCA, and therefore can be applied to an application range or a device on the premise of use of an organic material which is not preferable. The transparent substrate laminate included in the present invention can be used for a transparent panel used in a space where resistance to radiation such as α -rays is required, for example. The present invention includes an optoelectronic device, a solar cell for universe, a radiation-resistant solar cell, and a radiation-resistant optoelectronic device, each having a transparent substrate laminate. The present invention also includes a window material or a window used in aerospace devices, bodies, and buildings, including airplanes, artificial satellites, rockets, space stations, and the like, and a pressure-resistant glass including the transparent substrate laminate.

< Heat treatment >

The substrate laminate formed by bonding the substrates was further heated at 100 ℃, 150 ℃, or 200 ℃ as described above. It was confirmed that: the bonding strength after heating is generally increased as compared with the bonding strength without heating. The atmosphere in the heating treatment may be the atmosphere, or may be an inert gas such as nitrogen or argon.

As a method for bonding transparent substrates, the following techniques are known: a thin metal film is formed on the bonding surface of the transparent substrate, the substrates are bonded via the thin metal film, and the thin metal film sandwiched between the substrates is irradiated with laser light, whereby the substrates absorb the metal, and as a result, a substrate laminate having relatively high transparency is obtained. However, in this method, the metal may not be completely absorbed by the substrate, and a problem may occur in light transmittance. In electronic display devices such as smartphones, a polymer film including an organic EL element is often bonded to a transparent substrate. However, laser heating is not suitable for materials and members having low resistance such as polymer films. On the other hand, the method for forming a laminate of the present invention does not require high energy injection into the bonding interface, and is therefore also suitable for bonding a polymer film. Further, without interposing OCA, a laminate having high transparency and high adhesive force can be formed.

The substrates to be bonded may be flat or planar, or may have a non-flat shape. The substrate to be bonded may be a curved-surface-shaped tempered glass substrate, or may include tempered glass having a curved surface. The substrate and the laminate to be bonded may have an L-shaped cross section, an コ -shaped cross section, or an arc-shaped cross section. These substrates and laminates can be used for three-dimensional shaped electronic display devices such as smart phones, tablet computers, and the like having a display or optical element on a curved surface or a side surface.

The other substrate or the second substrate to be bonded may be a flexible substrate or may include a flexible substrate. The flexible substrate may contain optical elements.

OCAs are difficult to use for substrates with weak or large curvatures. The method of bonding substrates according to the present invention can avoid the use of OCA and can form a laminate having high transparency by directly bonding a functional film such as a deflection film and a protective glass via a metal oxide film.

In addition, in another embodiment, two of the pair of substrates to be bonded are glass substrates, and one of the substrates or the first substrate may be a glass substrate, and the second substrate may be a glass substrate having a smaller bonding area than the first substrate. In another embodiment, the second substrate may be a glass substrate having a frame shape or a frame shape along an edge of the first substrate. In addition, the second substrate may be bonded to a portion of the edge of the first substrate. For example, the first substrate may be a substantially rectangular flat glass substrate, and the second substrate may be bonded along a pair of opposing sides of the first substrate. In this case, the second substrate may include two or more substrates. All glass substrates in the present invention may be made of tempered glass, or may be substrates containing tempered glass.

The method for bonding substrates included in the present invention may further include: the first substrate is a glass substrate or a substrate including a glass substrate, the second substrate is a substrate having a bonding surface bonded to a part or the whole of an edge of the first substrate, and after the first substrate and the second substrate are bonded to each other, the bonded first substrate and second substrate are subjected to machining to form a curved glass substrate.

Alternatively, the method for bonding substrates included in the present invention may include: the first substrate and the second substrate are subjected to machining after bonding, and a curved surface is formed at least in a part thereof. The machining may include at least one of grinding and lapping. The machining may be performed by a method that avoids bending. A general tempered glass is weak to bending and is difficult to bend, and therefore, there is a problem that the tempered glass after bending becomes expensive. In contrast, the above method solves the problem, and enables a curved glass substrate or a curved strengthened glass substrate having a desired curved shape to be formed without bending or deforming at high temperature.

In still another embodiment, a method of bonding substrates includes: forming thin films 207, 208 of a first metal oxide on the bonding surface of the first substrate 202 and the first bonding surface of the second substrate 203; performing a first activation process on the surfaces of the thin films 207 and 208 of the first metal oxide on the bonding surface of the first substrate 202 and the first bonding surface 203 of the second substrate; bonding the first substrate 202 and the second substrate 203 by bringing the bonding surface of the first substrate 202 and the first bonding surface of the second substrate 203 into contact with each other through the metal oxide films 207 and 208; forming thin films 210, 211 of a second metal oxide on a second bonding surface of the second substrate 203 and a bonding surface of the third substrate 209; performing a second activation process on the surfaces of the second metal oxide thin films 210 and 211 on the second bonding surface of the second substrate 203 and the bonding surface of the third substrate 209; and bonding the second substrate 203 and the third substrate 209 by bringing the second bonding surface of the second substrate 202 and the bonding surface of the third substrate 209 into contact with each other through the thin films 210 and 211 of the second metal oxide. (FIG. 3)

In the substrate bonding method, the third substrate 209 may be bonded to the first substrate 202. In addition, a third substrate 209 may be bonded to the first substrate 202 and the second substrate 203. Namely, it may include: the bonding surface of the third substrate 209 is brought into contact with 3 the second bonding surface of the first substrate 202 and the second bonding surface of the second substrate 202, and the first substrate 201 and the second substrate 203 are bonded to the third substrate 209.

The first substrate 202 and the second substrate 203 may be transparent substrates, may be substrates made of tempered glass, or may be substrates made of tempered glass. In yet another embodiment, the third substrate may be a flexible substrate. As described above, it is difficult to bend a flat tempered glass, or the tempered glass after bending is expensive. Therefore, an electronic display device with high light extraction efficiency can be manufactured at lower cost.

In addition, the present invention includes electronic or optoelectronic or optical devices, including devices in general, fabricated by methods including any of the substrate bonding methods disclosed herein. In one embodiment, a device can include a laminate manufactured by a method including any one of the substrate bonding methods of the present invention. In another embodiment, the device may comprise an organic EL element. In another embodiment, the device may be a smartphone, a display device, a solar cell, a SAW filter device, or a building material such as a window or pressure-resistant glass.

While several embodiments and examples of the invention of the present application have been described above, these embodiments and examples are illustrative of the invention of the present application. The scope of the claims includes a plurality of modifications to the embodiments within a scope not departing from the technical idea of the invention of the present application. Therefore, the embodiments and examples disclosed in the present specification are disclosed for illustrative purposes and should not be construed as limiting the scope of the invention of the present application.

The claims (modification according to treaty clause 19)

1. A method for bonding substrates, comprising:

a step of forming a thin film of a metal oxide on a bonding surface of either or both of a pair of substrates at least one of which is a transparent substrate; and

a step of bringing the bonding surfaces of the pair of substrates into contact with each other via the thin film of the metal oxide,

the step of forming a thin film of a metal oxide on the bonding surface of the substrate includes: the film is formed by a sputtering method using a metal as a target and in a mixed gas consisting essentially of an inert gas and oxygen.

2. The method for bonding substrates according to claim 1, wherein the step of forming a thin film of a metal oxide on the bonding surface is performed by an ion beam sputtering method in which:

the step of forming a thin film of a metal oxide on the bonding surface of the substrate includes: the film is formed by a sputtering method using a metal as a target and in a mixed gas consisting essentially of an inert gas and oxygen.

3. The method for bonding substrates according to claim 1 or 2, wherein the step of forming a thin film of a metal oxide on the bonding surface is performed by an ALD method.

4. The method for bonding substrates according to any one of claims 1 to 3, further comprising a step of irradiating the bonding surface of the substrate with energetic particles before the step of forming a thin film of a metal oxide on the bonding surface.

5. The method for bonding substrates according to any one of claims 1 to 4, further comprising a step of irradiating energetic particles to a surface of the thin film of the metal oxide.

6. The method for bonding substrates according to claim 4, wherein the step of irradiating the surface of the thin film of metal oxide with energetic particles comprises: energy particles of a mixed gas substantially composed of an inert gas and oxygen are irradiated.

7. The method for bonding substrates according to any one of claims 1 to 6, wherein at least from the step of forming the thin film of the metal oxide to the step of bringing the bonding surfaces into contact with each other, the step is performed in vacuum.

8. A method of bonding substrates according to any one of claims 1 to 7, further comprising a step of performing a heat treatment after the step of bonding the substrates.

9. The method for bonding substrates according to claim 8, wherein the heat treatment is performed at 200 ℃ or lower.

10. The method for bonding substrates according to any one of claims 1 to 9, wherein two or any one of the substrates to be bonded is a transparent glass substrate.

11. The method of bonding substrates according to any one of claims 1 to 9, wherein one of the substrates to be bonded is a transparent glass substrate, and the other substrate is a substrate including an optical element.

12. The method for bonding substrates according to any one of claims 1 to 9, wherein the bonding surface of at least one of the substrates to be bonded is substantially made of a polymer material.

13. A device comprising a substrate laminate formed by the method for bonding substrates according to any one of claims 1 to 12.