Joint, method for manufacturing the joint, and light-emitting device

Abstract

This bonded body comprises: a first substrate; a second substrate; an inorganic film for bonding the first substrate and the second substrate; and a semiconductor layer formed on a surface opposite to a bonding surface of the second substrate. The first substrate is a glass having a SiO2 content of at most 70 mol%. The inorganic film includes a silicon oxide film formed on a bonding surface of the first substrate.

Description

[Technical Field]

[0001] This disclosure relates to a bonded body, a method for manufacturing a bonded body, and a light-emitting device. [Background technology]

[0002] Patent Document 1 discloses a bonding method for joining two substrates. This bonding method includes hydrophilizing at least one of the bonding surfaces of the two substrates to be joined, and joining the two substrates after hydrophilization. Hydrophilization includes reactive ion etching using oxygen gas, reactive ion etching using nitrogen gas, and irradiation with nitrogen radicals.

[0003] Patent Document 2 discloses a bonding method for joining two substrates. This bonding method includes forming a thin film of metal oxide on the bonding surface of both or one of a pair of substrates, and then bringing the bonding surfaces of the substrates into contact with each other via the thin film to bond them together. The substrates are glass containing SiO2, tempered glass, etc. In the examples, an aluminum oxide film is used as the thin film. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2018 / 084285 [Patent Document 2] International Publication No. 2019 / 131490 [Overview of the project] [Problems that the invention aims to solve]

[0005] As will be described in detail later, the inventors applied the technology described in Patent Document 1, the so-called sequential plasma method, to the bonding of glass to glass and to the bonding of glass to ceramic. The sequential plasma method is a technology for modifying the bonding surface of glass and the like.

[0006] When the modified bonding surface comes into contact with water vapor or water, hydrophilic OH groups are generated on the bonding surface. Subsequently, hydrogen bonds are formed between the OH groups during bonding, resulting in high bonding strength. After bonding, annealing treatment may be performed. Annealing treatment converts hydrogen bonds into covalent bonds, resulting in even higher bonding strength.

[0007] Experiments conducted by the inventors showed that when the bonding surface of quartz glass with an SiO2 content of 100 mol% was modified using a sequential plasma method, a higher bonding strength was obtained compared to when it was modified using only reactive ion etching with oxygen gas.

[0008] On the other hand, when the bonding surface of glass with an SiO2 content of 70 mol% or less was modified using the sequential plasma method, the bonding strength obtained was only about the same as when it was modified using only reactive ion etching with oxygen gas.

[0009] One aspect of this disclosure provides a technique for improving the bonding strength of glass with a low SiO2 content. [Means for solving the problem]

[0010] A bonded body according to one aspect of the present disclosure includes a first substrate, a second substrate, an inorganic film that bonds the first substrate and the second substrate, and a semiconductor layer formed on a surface of the second substrate opposite to the bonding surface. The first substrate is glass with an SiO2 content of 70 mol% or less. The inorganic film includes a silicon oxide film formed on the bonding surface of the first substrate. [Effects of the Invention]

[0011] According to one aspect of this disclosure, the bonding strength of glass with a low SiO2 content can be improved. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a cross-sectional view of a joint according to one embodiment. [Figure 2]FIG. 2 is a cross-sectional view showing the state before joining the first substrate and the second substrate of FIG. 1. [Figure 3] FIG. 3 is a flowchart showing a method for manufacturing a joined body according to an embodiment. [Figure 4] FIG. 4 is a cross-sectional view of a joined body according to a first modification example. [Figure 5] FIG. 5 is a cross-sectional view of a joined body according to a second modification example. [Figure 6] FIG. 6 is a cross-sectional view of a joined body according to a third modification example. [Figure 7] FIG. 7 is a cross-sectional view of a joined body according to a fourth modification example. [Figure 8] FIG. 8 is a cross-sectional view showing an example of the state before joining the lens which is the first substrate. [Figure 9] FIG. 9 is a cross-sectional view showing an example of a method for measuring joining strength. [Figure 10] FIG. 10 is a cross-sectional view showing another example of the state before joining the lens which is the first substrate. [Figure 11] FIG. 11 is a cross-sectional view of a light-emitting device according to an embodiment. [Figure 12] FIG. 12 is a cross-sectional view of a light-emitting device according to a first modification example. [Figure 13] FIG. 13 is a cross-sectional view of a light-emitting device according to a second modification example. [Figure 14] FIG. 14 is a cross-sectional view of the die share test of Example 14. [Figure 15] FIG. 15 is a cross-sectional view of the die share test of Example 15.

MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same reference numerals, and the description thereof may be omitted. In the specification, "~" indicating a numerical range means that the numerical values described before and after it are included as the lower limit value and the upper limit value. In the specification, a plan view means viewing from a direction orthogonal to the joining surface.

[0014] As will be described in detail later, the inventors applied the technology described in Patent Document 1, the so-called sequential plasma method, to the bonding of glass to glass and glass to ceramic. The sequential plasma method includes, for example, reactive ion etching using oxygen gas, reactive ion etching using nitrogen gas, and irradiation with nitrogen radicals.

[0015] Hereafter, reactive ion etching (RIE) using oxygen gas will also be referred to as "oxygen RIE." Similarly, reactive ion etching using nitrogen gas will also be referred to as "nitrogen RIE." Note that the sequential plasma method only needs to include nitrogen RIE and irradiation with nitrogen radicals, and does not necessarily need to include oxygen RIE.

[0016] The sequential plasma method modifies the bonding surface of glass or other materials. When the modified bonding surface comes into contact with water vapor or water, hydrophilic OH groups are generated on the bonding surface. Subsequently, hydrogen bonds are formed between the OH groups during bonding, resulting in high bonding strength. After bonding, annealing may be performed. Annealing converts hydrogen bonds into covalent bonds, resulting in even higher bonding strength.

[0017] Experiments conducted by the inventors showed that when the bonding surface of quartz glass with an SiO2 content of 100 mol% was modified using the sequential plasma method, a higher bonding strength was obtained compared to when it was modified using oxygen RIE alone.

[0018] On the other hand, when the bonding surface of glass with an SiO2 content of 70 mol% or less was modified using the sequential plasma method, the bonding strength was only about the same as when it was modified using oxygen RIE alone.

[0019] The inventors conducted further experiments and found that if at least one of the two substrates to be joined is a glass with a low SiO2 content, the bonding strength can be improved by the sequential plasma method if a silicon oxide film is formed on the bonding surface of that glass.

[0020] Before surface modification, the silicon oxide film, like quartz glass, contains virtually no impurities other than oxygen and silicon. Therefore, modifying the bonding surface of the silicon oxide film using sequential plasma technology can achieve a bonding strength comparable to that obtained when modifying the bonding surface of quartz glass using sequential plasma technology.

[0021] Furthermore, the silicon oxide film after bonding contains 1 atomic percent or more of nitrogen atoms, as determined by energy-dispersive X-ray analysis. The nitrogen atom content is preferably 1.5 atomic percent or more, and preferably 10 atomic percent or less.

[0022] As shown in Figure 1, the bonded body 1 includes a first substrate 2, a second substrate 3, and an inorganic film 4. The inorganic film 4 bonds the first substrate 2 and the second substrate 3. The inorganic film 4 contains a silicon oxide film. Unlike organic films composed of so-called adhesives, the inorganic film 4 does not flow during bonding, thus preventing misalignment and tilting. Furthermore, since the thickness of the inorganic film 4 is generally smaller than the wavelength of light, even if there is a refractive index difference between the first substrate 2 or the second substrate 3 and the inorganic film 4, very little light is reflected between them.

[0023] As shown in Figure 2, the inorganic film 4 includes, for example, a first silicon oxide film 5 and a second silicon oxide film 6. The first silicon oxide film 5 is formed on the bonding surface 21 of the first substrate 2 before the first substrate 2 and the second substrate 3 are joined. On the other hand, the second silicon oxide film 6 is formed on the bonding surface 31 of the second substrate 3 before the first substrate 2 and the second substrate 3 are joined.

[0024] Furthermore, if the second substrate 3 is quartz glass or quartz, the second silicon oxide film 6 may be omitted. In this case, if the bonding surface of the quartz glass, etc., is modified using the sequential plasma method, a higher bonding strength can be obtained compared to when it is modified using oxygen RIE alone.

[0025] The first substrate 2 has a bonding surface 21 facing the second substrate 3. The bonding surface 21 is a flat surface. In this embodiment, the first substrate 2 is plate-shaped, but as will be described later, it may be lens-shaped or prism-shaped, etc., and its shape is not particularly limited. It is sufficient that the bonding surface 21 is a flat surface. The first substrate 2 has, for example, visible light transmittance. The visible light transmittance of the first substrate 2 is, for example, 90% to 100%.

[0026] The first substrate 2 is, for example, soda-lime glass, alkali-free glass, chemically strengthened glass, or lanthanum borate glass. Chemically strengthened glass is used for display cover glass, etc. Lanthanum borate glass is used for lenses or prisms, etc.

[0027] The first substrate 2 is glass with an SiO2 content of 70 mol% or less. By forming a silicon oxide film on the bonding surface 21 of the glass, the bonding strength can be improved by the sequential plasma method. The SiO2 content of the glass is preferably 66 mol% or less, more preferably 60 mol% or less, and even more preferably 10 mol% or less. The SiO2 content of the glass is 0 mol% or more.

[0028] The first substrate 2 may be glass with a total content of Al2O3 and B2O3 of 5 mol% or more. From the results of experiments described later, it is estimated that if the bonding surface modified by the sequential plasma method contains a large amount of Al2O3 and B2O3, the modification effect may not be sufficiently obtained.

[0029] If the total content of Al2O3 and B2O3 in the glass is 5 mol% or more, the bonding strength can be improved by sequential plasma by forming a silicon oxide film on the bonding surface 21 of the glass. The total content of Al2O3 and B2O3 is preferably 10 mol% or more, more preferably 15 mol% or more, and particularly preferably 60 mol% or more. The total content of Al2O3 and B2O3 is preferably 70 mol% or less in order to stabilize the glass structure.

[0030] The Young's modulus E1 of the first substrate 2 is, for example, 40 GPa to 200 GPa, preferably 40 GPa to 150 GPa. If E1 is 150 GPa or less, the bonding surface 21 of the first substrate 2 is more likely to deform to conform to the minute irregularities of the bonding surface 31 of the second substrate 3 during bonding, thereby suppressing the generation of minute voids. E1 is preferably 120 GPa or less.

[0031] The maximum thickness t1 of the first substrate 2 is, for example, 0.05 mm to 5 mm, preferably 0.05 mm to 2.5 mm. t1 is measured in a direction perpendicular to the joining surface 21. If t1 is 2.5 mm or less, the joining surface 21 of the first substrate 2 is more likely to deform to conform to the minute irregularities of the joining surface 31 of the second substrate 3 during joining, thereby suppressing the generation of minute voids. t1 is preferably 2 mm or less.

[0032] The product of the Young's modulus E1 and the maximum thickness t1 of the first substrate 2 (E1 × t1) is, for example, 35 GPa·mm to 200 GPa·mm, preferably 35 GPa·mm to 180 GPa·mm, and more preferably 35 GPa·mm to 150 GPa·mm. If E1 × t1 is 150 GPa·mm or less, the bonding surface 21 of the first substrate 2 is more likely to deform to conform to the minute irregularities of the bonding surface 31 of the second substrate 3 during bonding, thereby suppressing the generation of minute voids.

[0033] The surface roughness Ra of the bonding surface 21 of the first substrate 2 is, for example, 0.01 nm to 1 nm. If the surface roughness Ra of the bonding surface 21 is 1 nm or less, the flatness of the bonding surface 21 is high, and the generation of minute voids can be suppressed. Preferably, the surface roughness Ra of the bonding surface 21 is 0.5 nm or less. Ra is the "arithmetic mean roughness" as described in the Japanese Industrial Standard JIS B0601:1994.

[0034] The average linear expansion coefficient α1 of the first substrate 2 at 50°C to 200°C is, for example, 0.1 ppm / °C to 20 ppm / °C, preferably 0.5 ppm / °C to 10 ppm / °C. The average linear expansion coefficient is measured in accordance with the Japanese Industrial Standard JIS R 3102:1995.

[0035] The second substrate 3 has a bonding surface 31 facing the first substrate 2. The bonding surface 31 is a flat surface. In this embodiment, the second substrate 3 is plate-shaped, but its shape is not particularly limited. It is sufficient that the bonding surface 31 is a flat surface. The second substrate 3 has, for example, visible light transmittance. The visible light transmittance of the second substrate 3 is, for example, 90% to 100%.

[0036] The second substrate 3 is constructed in the same manner as the first substrate 2. The second substrate 3 is, for example, soda-lime glass, alkali-free glass, chemically strengthened glass, or lanthanum borate glass. Chemically strengthened glass is used for display cover glass, etc. Lanthanum borate glass is used for lenses or prisms, etc.

[0037] The second substrate 3 is, for example, glass with an SiO2 content of 70 mol% or less. By forming a silicon oxide film on the bonding surface 31 of the glass, the bonding strength can be improved by the sequential plasma method. The SiO2 content of the glass is preferably 66 mol% or less, more preferably 60 mol% or less, and even more preferably 10 mol% or less. The SiO2 content of the glass is 0 mol% or more.

[0038] The second substrate 3 may be glass with a total content of Al2O3 and B2O3 of 5 mol% or more. If a silicon oxide film is formed on the bonding surface 31 of the glass, the bonding strength can be improved by the sequential plasma method. The total content of Al2O3 and B2O3 is preferably 10 mol% or more, more preferably 15 mol% or more, and particularly preferably 60 mol% or more. The total content of Al2O3 and B2O3 is preferably 70 mol% or less in order to stabilize the glass structure.

[0039] Unlike the first substrate 2, the second substrate 3 is not limited to glass. The second substrate 3 may be an inorganic single crystal or inorganic polycrystalline material with an SiO2 content of 70 mol% or less, and may be, for example, sapphire (aluminum oxide) or aluminum nitride. If a silicon oxide film is formed on the bonding surface 31, the bonding strength can be improved by the sequential plasma method.

[0040] The sapphire substrate or aluminum nitride substrate, as will be described in more detail later, can be used, for example, as a substrate for a light-emitting element 7, as shown in Figures 6 and 7. The light-emitting element 7 has a second substrate 3 and a semiconductor layer 8 formed on the non-bonding surface 32 of the second substrate 3, opposite to the bonding surface 31. The light-emitting element 7 may further have electrodes. The sapphire substrate or aluminum nitride substrate may also be used as a substrate for semiconductor elements other than light-emitting elements, such as photodetectors.

[0041] The second substrate 3 may be a resin. Examples of resins include PEN (polyethylene naphthalate), PET (polyethylene terephthalate), other polyester materials, PI (polyimide), COP (cycloolefin polymer), or PC (polycarbonate). By forming a silicon oxide film on the bonding surface 31 of these resins, the bonding strength can be improved by the sequential plasma method.

[0042] The Young's modulus E2 of the second substrate 3 is, for example, 40 GPa to 500 GPa, preferably 40 GPa to 150 GPa. If E2 is 150 GPa or less, the bonding surface 31 of the second substrate 3 is more likely to deform to conform to the minute irregularities of the bonding surface 21 of the first substrate 2 during bonding, thereby suppressing the generation of minute voids. E2 is preferably 120 GPa or less.

[0043] The maximum thickness t2 of the second base material 3 is, for example, 0.05 mm to 5 mm, preferably 0.05 mm to 2 mm. t2 is measured in a direction perpendicular to the joining surface 31. If t2 is 2 mm or less, the joining surface 31 of the second base material 3 is more likely to deform to conform to the minute irregularities of the joining surface 21 of the first base material 2 during joining, thereby suppressing the generation of minute voids. t2 is preferably 1 mm or less.

[0044] The product of the Young's modulus E2 and the maximum thickness t2 of the second substrate 3 (E2 × t2) is, for example, 35 GPa·mm to 200 GPa·mm. If E2 × t2 is 200 GPa·mm or less, the bonding surface 31 of the second substrate 3 is more likely to deform to conform to the minute irregularities of the bonding surface 21 of the first substrate 2 during bonding, thereby suppressing the generation of minute voids. E2 × t2 is preferably 150 GPa·mm or less, and more preferably 120 GPa·mm or less.

[0045] The sum of E1×t1 of the first substrate 2 and E2×t2 of the second substrate 3 (E1×t1+E2×t2) is, for example, 70 GPa·mm to 300 GPa·mm. If E1×t1+E2×t2 is 300 GPa·mm or less, the joining surface 21 of the first substrate 2 and the joining surface 31 of the second substrate 3 can easily deform to conform to each other's minute irregularities during joining, thereby suppressing the generation of minute voids. E1×t1+E2×t2 is preferably 270 GPa·mm or less.

[0046] The surface roughness Ra of the bonding surface 31 of the second substrate 3 is, for example, 0.01 nm to 1 nm. If the surface roughness Ra of the bonding surface 31 is 1 nm or less, the flatness of the bonding surface 31 is high, and the generation of minute voids can be suppressed. Preferably, the surface roughness Ra of the bonding surface 31 is 0.5 nm or less.

[0047] The average linear expansion coefficient α2 of the second substrate 3 at 50°C to 200°C is, for example, 0.1 ppm / °C to 20 ppm / °C, preferably 0.5 ppm / °C to 10 ppm / °C. The difference (|α1-α2|) between the average linear expansion coefficients of the first substrate 2 and the second substrate 3 at 50°C to 200°C is, for example, 0.0 ppm / °C to 4.0 ppm / °C. If |α1-α2| is 4.0 ppm / °C or less, the thermal stress generated in the annealing (step S7) described later can be reduced, and delamination at the joint surface or fracture of the jointed body 1 can be suppressed.

[0048] The first silicon oxide film 5 is formed on the bonding surface 21 of the first substrate 2. The first silicon oxide film 5 is, for example, an SiO2 film. The first silicon oxide film 5 is not limited to having a stoichiometric composition. In other words, the first silicon oxide film 5 is not limited to having a silicon-to-oxygen molar ratio of 1:2.

[0049] The method for depositing the first silicon oxide film 5 is, for example, sputtering. The sputtering method may also be reactive sputtering. Reactive sputtering uses a metal target and a mixed gas of an inert gas (such as a rare gas) and a reactive gas (such as oxygen gas) to form a metal oxide on the target substrate. Sputtering may also use a metal oxide target.

[0050] Furthermore, the method for depositing the first silicon oxide film 5 is not limited to sputtering, but may also be plasma CVD (Chemical Vapor Deposition), evaporation, or ALD (Atomic Layer Deposition).

[0051] The thickness of the first silicon oxide film 5 is, for example, 1 nm to 100 nm. If the thickness of the first silicon oxide film 5 is 1 nm or more, the modification effect of the sequential plasma method can be obtained. On the other hand, if the thickness of the first silicon oxide film 5 is 100 nm or less, the deterioration of the surface roughness Ra can be suppressed.

[0052] The thickness of the first silicon oxide film 5 is preferably 75 nm or less, more preferably 50 nm or less, even more preferably 30 nm or less, even more preferably 20 nm or less, particularly preferably 10 nm or less, and even more particularly preferably 5 nm or less.

[0053] The surface roughness Ra of the bonding surface 51 of the first silicon oxide film 5 is, for example, 0.01 nm to 1 nm. If the surface roughness Ra of the bonding surface 51 is 1 nm or less, the flatness of the bonding surface 51 is high, and the generation of minute voids can be suppressed. Preferably, the surface roughness Ra of the bonding surface 51 is 0.5 nm or less.

[0054] The second silicon oxide film 6 is formed on the bonding surface 31 of the second substrate 3. The second silicon oxide film 6 is, for example, an SiO2 film. The second silicon oxide film 6 is not limited to having a stoichiometric composition. In other words, the second silicon oxide film 6 is not limited to having a silicon-to-oxygen molar ratio of 1:2. The method for forming the second silicon oxide film 6 is the same as the method for forming the first silicon oxide film 5.

[0055] The thickness of the silicon dioxide film 6 is, for example, 1 nm to 100 nm. If the thickness of the silicon dioxide film 6 is 1 nm or more, the modification effect of the sequential plasma method can be obtained. On the other hand, if the thickness of the silicon dioxide film 6 is 100 nm or less, the deterioration of the surface roughness Ra can be suppressed.

[0056] The thickness of the silicon dioxide film 6 is preferably 75 nm or less, more preferably 50 nm or less, even more preferably 30 nm or less, even more preferably 20 nm, particularly preferably 10 nm or less, and even more particularly preferably 5 nm or less.

[0057] The combined thickness of the first silicon oxide film 5 and the second silicon oxide film 6 is between 1 nm and 200 nm.

[0058] The surface roughness Ra of the bonding surface 61 of the silicon dioxide film 6 is, for example, 0.01 nm to 1 nm. If the surface roughness Ra of the bonding surface 61 is 1 nm or less, the flatness of the bonding surface 61 is high, and the generation of minute voids can be suppressed. Preferably, the surface roughness Ra of the bonding surface 61 is 0.5 nm or less.

[0059] As mentioned above, if the second substrate 3 is quartz glass or quartz, the second silicon oxide film 6 may be omitted. In this case, if the bonding surface of the quartz glass, etc., is modified using the sequential plasma method, a higher bonding strength can be obtained compared to when it is modified using oxygen RIE alone.

[0060] Next, with reference to Figure 3, a method for manufacturing the bonded body 1 will be described. The method for manufacturing the bonded body 1 includes, for example, the formation of a silicon oxide film (step S1), oxygen RIE (step S2), nitrogen RIE (step S3), irradiation with nitrogen radicals (step S4), supply of water molecules (step S5), bonding (step S6), and annealing (step S7).

[0061] The manufacturing method for the bonded body 1 may include steps S1 and S3-S6, but may not include steps S2 and S7. Furthermore, the modification of the first silicon oxide film 5 (steps S2-S5) and the modification of the second silicon oxide film 6 (steps S2-S5) do not have to be performed simultaneously, but may be performed sequentially.

[0062] Step S1 includes forming a first silicon oxide film 5 on the bonding surface 21 of the first substrate 2. Step S1 also includes forming a second silicon oxide film 6 on the bonding surface 31 of the second substrate 3. Note that the first silicon oxide film 5 and the second silicon oxide film 6 do not have to be formed simultaneously, but may be formed sequentially. The film formation method is as described above, such as sputtering.

[0063] Step S2 includes applying oxygen RIE to the bonding surface 51 of the first silicon oxide film 5. Step S2 also includes applying oxygen RIE to the bonding surface 61 of the second silicon oxide film 6. The oxygen RIE includes, for example, holding the substrate on a stage in the processing container, discharging residual gas from the processing container, introducing oxygen gas into the processing container, and applying a high-frequency bias to the substrate held on the stage. The frequency of the high-frequency bias is, for example, 13.56 MHz. The application of the high-frequency bias generates a sheath region near the bonding surface of the silicon oxide film. The sheath region is a region where oxygen ions repeatedly collide with the bonding surface of the silicon oxide film. The collision of oxygen ions etches the bonding surface of the silicon oxide film. A mixed gas of oxygen gas and a rare gas may be introduced into the processing container.

[0064] Step S3 includes applying nitrogen RIE to the bonding surface 51 of the first silicon oxide film 5. Step S3 also includes applying nitrogen RIE to the bonding surface 61 of the second silicon oxide film 6. Nitrogen RIE includes, for example, holding the substrate on a stage in the processing container, discharging residual gas from the processing container, introducing nitrogen gas into the processing container, and applying a high-frequency bias to the substrate held on the stage. The frequency of the high-frequency bias is, for example, 13.56 MHz. The application of the high-frequency bias generates a sheath region near the bonding surface of the silicon oxide film. The sheath region is a region where nitrogen ions repeatedly collide with the bonding surface of the silicon oxide film. The collision of nitrogen ions etches the bonding surface of the silicon oxide film. A mixed gas of nitrogen gas and a rare gas may be introduced into the processing container.

[0065] Step S4 includes irradiating the bonding surface 51 of the first silicon oxide film 5 with nitrogen radicals. Step S4 also includes irradiating the bonding surface 61 of the second silicon oxide film 6 with nitrogen radicals. The irradiation of nitrogen radicals includes, for example, holding the substrate on a stage in the processing vessel, discharging residual gas from the processing vessel, introducing nitrogen gas into the processing vessel, and plasmaizing the nitrogen gas with microwaves or the like. The microwave frequency is, for example, 2.45 GHz. The plasma is not limited to microwave plasma, but may be capacitively coupled plasma or inductively coupled plasma, etc. It is sufficient that nitrogen radicals are generated. Irradiation with nitrogen radicals forms sites for the attachment of OH groups. Sites for the attachment of OH groups can also be formed with oxygen RIE and nitrogen RIE.

[0066] Step S5 includes supplying water molecules to the bonding surface 51 of the first silicon oxide film 5. Step S5 also includes supplying water molecules to the bonding surface 61 of the second silicon oxide film 6. The supply of water molecules includes, for example, removing the substrate from the processing container and exposing the removed substrate to the atmosphere. OH groups are formed on the bonding surface of the silicon oxide film by water molecules in the atmosphere. Note that the supply of water molecules may be carried out inside the processing container. For example, water molecules can be supplied by introducing water vapor gas into the processing container. The water molecules may be in gaseous or liquid form.

[0067] Step S6 includes joining the first substrate 2 and the second substrate 3 to obtain a joined body 1. The joining of the first substrate 2 and the second substrate 3 may be carried out under atmospheric pressure or under a reduced pressure atmosphere. It is preferable to carry out the joining under a reduced pressure atmosphere in order to suppress the formation of voids. Since OH groups are already formed on the joining surface 51 of the first silicon oxide film 5 and the joining surface 61 of the second silicon oxide film 6, hydrogen bonds are formed between the OH groups, and high bonding strength is obtained. Step S6 may also include applying pressure so as to press the first substrate 2 and the second substrate 3 together.

[0068] Step S7 includes heating and annealing the joint 1. Hydrogen bonds are converted into covalent bonds, resulting in higher joint strength. The heating temperature of the joint 1 is, for example, 120°C to 200°C. The heating time of the joint 1 is, for example, 10 minutes to 7 hours. Annealing not only improves joint strength but can also increase the contact area between the joint surfaces and reduce voids.

[0069] The bonding strength of the bonded body 1 is measured by the crack opening method shown in Figure 9. The inorganic film 4 is not shown in Figure 9. In the crack opening method, a blade BL, like a razor blade, is inserted from the outside into the bonding interface between the first substrate 2 and the second substrate 3 that are bonded together, and the peeling length L is measured. The shorter the peeling length L, the higher the bonding strength. If the bonding strength is sufficiently high, the insertion of the blade BL will destroy either the first substrate 2 or the second substrate 3.

[0070] When calculating the joint strength γ from the delamination length L, use the following equation (1).

[0071]

number

[0072] Next, with reference to Figure 4, the joint 1 according to the first modified example will be described. The joint 1 of this modified example has a wedge-shaped groove N on the outer edge of the joining interface between the first substrate 2 and the second substrate 3 (more specifically, the joining interface between the first silicon oxide film 5 and the second silicon oxide film 6). The groove N is formed over the entire outer edge of the joining interface, but it may also be formed only on a part of the outer edge of the joining interface.

[0073] If a groove N is present, after bonding (step S6) and before annealing (step S7), a blade such as a razor blade can be inserted into the groove N to separate the first substrate 2 and the second substrate 3, and the first substrate 2 and the second substrate 3 can be reattached. Reattachment is performed before annealing to suppress damage to the substrates.

[0074] In a plan view, the first base material 2 and the second base material 3 are of roughly the same size and have overlapping contours. In this case, the groove N is formed between the chamfered surface 23 of the first base material 2 and the chamfered surface 33 of the second base material 3. Although the chamfered surfaces 23 and 33 are R-chamfered surfaces in Figure 4, they may also be C-chamfered surfaces. Note that the chamfered surface may be formed on only one of the first base material 2 or the second base material 3. It is sufficient that the groove N is formed.

[0075] The depth NC of the groove N is measured in a direction perpendicular to the outer edge of the first base material 2, etc., in a plan view. The depth NC is, for example, 0.05 mm to 0.5 mm, preferably 0.1 mm to 0.3 mm. If the depth NC is 0.05 mm or more, blade insertion is easy. Also, if the depth NC is 0.5 mm or less, the formation of cracks originating from the groove N can be suppressed.

[0076] Next, with reference to Figure 5, the joint 1 relating to the second modified example will be described. The joint 1 of this modified example has a wedge-shaped groove N, similar to the first modified example described above. Unlike the first modified example described above, in a plan view, the first base material 2 is smaller than the second base material 3, and the contour of the first base material 2 is inside the contour of the second base material 3.

[0077] The reference point (the point where NC=0) for the depth NC of the groove N is the outer edge of the first base material 2. The depth NC is, for example, 0.05 mm to 0.5 mm, and preferably 0.1 mm to 0.3 mm. If the depth NC is 0.05 mm or more, blade insertion is easy. Also, if the depth NC is 0.5 mm or less, the formation of cracks originating from the groove N can be suppressed.

[0078] In this modified example, the first substrate 2 is smaller than the second substrate 3 in plan view, and the contour of the first substrate 2 lies inside the contour of the second substrate 3. However, the second substrate 3 may also be smaller than the first substrate 2 in plan view, and the contour of the second substrate 3 lies inside the contour of the first substrate 2. In the latter case, the reference point for the depth NC of the groove N (the point where NC=0) is the outer edge of the second substrate 3.

[0079] Next, with reference to Figure 6, the joint 1 according to the third modified example will be described. In the joint 1 of this modified example, the first base material 2 is a lens. The first base material 2 is, for example, a spherical lens with a convex surface on the side opposite to the joining surface of the first base material 2. The light emitted by the light-emitting element 7, which will be described later, is extracted to the outside through the lens.

[0080] The light-emitting surface of the lens is curved to reduce total internal reflection. The lens is, for example, a plano-convex lens. The lens can be either a spherical or aspherical lens, but a spherical lens is preferred from the viewpoint of light extraction efficiency.

[0081] By attaching the lens to the light-emitting element 7, the light extraction efficiency is improved by two to three times. The application of the lens is not particularly limited; depending on the application, the lens may be a plano-concave lens.

[0082] The light-emitting element 7 is formed before the first substrate 2 and the second substrate 3 are joined. The substrate for the light-emitting element 7 is the second substrate 3. As the second substrate 3, a sapphire substrate (aluminum oxide substrate) or an aluminum nitride substrate can be used. The light-emitting element 7 is, for example, an ultraviolet light-emitting element. The ultraviolet light can be any of UVC (wavelength 200nm to 280nm), UVB (wavelength 280nm to 315nm), or UVA (wavelength 315nm to 400nm). The light-emitting element 7 may also be a visible light-emitting element or an infrared light-emitting element.

[0083] Since the thickness of the inorganic film 4 can be made thinner than the wavelength of the light emitted by the light-emitting element 7, total internal reflection occurring at the interface between the second substrate 3 and the inorganic film 4 can be suppressed, and light is efficiently transmitted from the second substrate 3 through the inorganic film 4 to the first substrate 2. Therefore, by joining the first substrate 2 and the second substrate 3 using the inorganic film 4, the light emitted by the light-emitting element 7 is extracted to the outside of the light-emitting element 7 through the inorganic film 4 and the first substrate 2, greatly improving the light extraction efficiency of the light-emitting element 7.

[0084] On the other hand, when the first substrate 2 and the second substrate 3 are joined using an organic film composed of a resin adhesive, the thickness of the organic film becomes greater than the wavelength of light emitted from the light-emitting element 7. As a result, total internal reflection at the interface between the second substrate 3 and the organic film cannot be suppressed, and the light extraction efficiency becomes low. Therefore, by joining the first substrate 2 and the second substrate 3 using an inorganic film 4, the light extraction efficiency can be improved compared to when an organic film is used, and the light output of the light-emitting element 7 can be greatly improved.

[0085] Next, with reference to Figure 7, the joint 1 relating to the fourth modified example will be described. In the third modified example described above, in a plan view, the first base material 2 and the second base material 3 are of roughly the same size and have overlapping contours. In contrast, in this modified example, in a plan view, the first base material 2 is larger than the second base material 3 and protrudes outside the second base material 3.

[0086] The protruding portion of the first substrate 2 can be grasped, allowing the first substrate 2 and the second substrate 3 to be separated and then reattached. This reattachment is performed before annealing to minimize damage to the substrates. In a plan view, it is sufficient if more than 30% of the outer edge of the first substrate 2 protrudes outside the second substrate 3.

[0087] Figure 8 shows an example of the state of the lens, which is the first substrate 2, before bonding. The lens, which is the first substrate 2, will also be referred to as lens 2. Before bonding lens 2 to the second substrate 3, the bonding surface 21 of lens 2 facing the second substrate 3 may be a convex curved surface. A convex curved surface is a dome-shaped curved surface in which the center protrudes more than the periphery. The maximum height difference ΔH of the bonding surface 21 is, for example, 5 nm to 400 nm. ΔH is measured, for example, with a white light interferometer, excluding the region within 400 μm from the outer edge of the bonding surface 21.

[0088] If ΔH is 5 nm or greater, stress can be concentrated at the center of the bonding surface 21, allowing bonding to proceed with a small load and preventing damage to the light-emitting element 7. On the other hand, if ΔH is 400 nm or less, the adhesion of the bonding interface is good after bonding the lens 2 and the second substrate 3. ΔH is preferably 10 nm to 300 nm, and more preferably 15 nm to 250 nm.

[0089] As shown in Figure 10, before bonding the lens 2 to the second substrate 3, a portion of the bonding surface 21 of the lens 2 may be a convex curved surface. Of the bonding surface 21, the region 21a that overlaps with the second substrate 3 in a plan view after bonding only needs to be a convex curved surface. The region that does not overlap with the second substrate 3 may be a flat surface. The maximum height difference ΔHA of region 21a is, for example, 5 nm to 200 nm. ΔHA is measured, for example, with a white light interferometer.

[0090] If ΔHA is 5 nm or greater, stress can be concentrated at the center of the bonding surface 21, allowing bonding to proceed with a small load and preventing damage to the light-emitting element 7. On the other hand, if ΔHA is 200 nm or less, the adhesion of the bonding interface is good after bonding the lens 2 and the second substrate 3. ΔHA is preferably 10 nm to 150 nm, and more preferably 15 nm to 100 nm.

[0091] Furthermore, as shown in Figure 8, even when the entire bonding surface 21 is a convex curved surface, it is preferable that the maximum height difference ΔHA of a portion of the bonding surface 21a is 5 nm to 200 nm. Since region 21a is a portion of the bonding surface 21, the maximum height difference ΔHA of region 21a is smaller than the maximum height difference ΔH of the bonding surface 21.

[0092] As shown in Figures 11 to 13, the light-emitting device 100 comprises a bonding body 1 and a container 101 that houses the bonding body 1. The bonding body 1 has a lens 2 and a light-emitting element 7. A prism or the like may be used instead of the lens 2, and the bonding body 1 only needs to have an optical member and a light-emitting element 7. The light-emitting element 7 is, for example, an ultraviolet light-emitting element. The light-emitting element 7 has a second substrate 3 and a semiconductor layer 8. The second substrate 3 is, for example, a sapphire substrate or an aluminum nitride substrate. The semiconductor layer 8 is formed on the non-bonding surface of the second substrate 3, opposite to the bonding surface that bonds with the lens 2.

[0093] The container 101 includes a substrate 102 and a cover 103, as shown in Figure 11, for example. A recess 104 for housing the bonded body 1 is formed on the surface 102a of the substrate 102. The light-emitting element 7 is fixed to the inner bottom surface of the recess 104. The light-emitting element 7 is fixed by a known method such as die bonding. The light-emitting element 7 is fixed to the substrate 102 after the light-emitting element 7 and the lens 2 are bonded together, but the order may be reversed, and the light-emitting element 7 may be fixed to the substrate 102 before the light-emitting element 7 and the lens 2 are bonded together.

[0094] The assembly 1 is fixed with the lens 2 facing the cover 103. The cover 103 is made of a material that transmits light emitted from the light-emitting element 7. The light emitted from the light-emitting element 7 passes through the lens 2 and the cover 103 in that order. The cover 103 is flat and is bonded to the surface 102a of the substrate 102.

[0095] The cover 103 is made of a material that transmits light emitted from the light-emitting element 7. Examples of such materials include quartz or inorganic glass. The cover 103 and the substrate 102 are bonded together with metal solder, inorganic adhesive, or organic adhesive. This bonding prevents the intrusion of moisture and other external elements, thereby suppressing performance degradation of the light-emitting element 7.

[0096] The cover 103 is flat as shown in Figure 11, but it may also be box-shaped as shown in Figure 12, or dome-shaped as shown in Figure 13. When the cover 103 is box-shaped or dome-shaped, the light radiating from the lens 2 can be efficiently extracted to the outside. In the case of a dome shape, the light extraction efficiency is particularly good. Also, when the cover 103 is box-shaped or dome-shaped, a recess 104 is not formed on the surface 102a of the substrate 102, so the cost of the substrate 102 can be reduced. [Examples]

[0097] The experimental data is described below. First, Table 1 shows the compositions of the four types of glass A to D used in the experiment.

[0098] [Table 1] Glass A is alkali-free glass. Glass B is alkali metal oxide-containing glass. Glass C is alkali-free glass. Glass D is lanthanum borate-based glass. Glasses A through D all have an SiO2 content of 70 mol% or less.

[0099] In Examples 1 to 15 below, glass bonding or glass-to-ceramic bonding was performed using glasses A to D listed in Table 1. The bonding conditions and evaluation results are shown in Tables 2 to 4. Examples 1 to 7 and Examples 13 to 14 below are examples, and Examples 8 to 12 and Example 15 below are comparative examples. In Example 16, quartz glass (SiO2 content: 100 mol%) was bonded to ceramic. The bonding conditions and evaluation results are shown in Table 4. Example 16 is a reference example.

[0100] [Table 2]

[0101] [Table 3]

[0102] [Table 4] In Tables 2 to 4, the first bonding film is an inorganic film formed on the bonding surface of the first substrate before bonding the first and second substrates. Similarly, the second bonding film is an inorganic film formed on the bonding surface of the second substrate before bonding the first and second substrates. The bonding conditions and evaluation results for Examples 1 to 15 will be described in detail below.

[0103] In Example 1, glass substrates made of glass A were prepared as the first and second substrates. An SiO2 film was deposited on the bonding surface of each glass substrate by reactive sputtering. Metallic silicon was used as the target for reactive sputtering. The bonding surface of each SiO2 film was modified by sequential plasma irradiation. Specifically, oxygen RIE, nitrogen RIE, and nitrogen radical irradiation were performed in this order, and then the surface was exposed to air to deposit OH groups. The oxygen RIE treatment time was 180 seconds, the nitrogen RIE treatment time was 180 seconds, and the nitrogen radical irradiation time was 15 seconds. After that, the two glass substrates were bonded together via the two modified SiO2 films. A wedge-shaped groove was formed on the outer edge of the bonding interface. This groove was formed between the chamfered surfaces. The depth of the groove was 0.28 mm. When a razor blade was inserted into the groove, the two glass substrates could be separated. Subsequently, the two separated glass substrates were rejoined, and the resulting bond was annealed at 200°C for 2 hours. The bond strength after annealing was measured by the crack opening method. As a result, fracture of the glass substrate occurred, indicating that the bond strength was sufficiently high. In Example 1, the nitrogen concentration of the two bonded SiO2 films was measured by energy-dispersive X-ray analysis, and the nitrogen concentration of the SiO2 films was 1.8 atomic percent.

[0104] The nitrogen concentration in the SiO2 film after bonding was measured by energy-dispersive X-ray spectroscopy using a scanning transmission electron microscope. The bonded body was cut perpendicular to the bonding interface to expose the cross-section, and the bonded body was thinned by polishing using an appropriate method. Elemental mapping was performed on the thinned bonded body using energy-dispersive X-ray spectroscopy in the rectangular region containing the SiO2 film at the bonding interface using a scanning transmission electron microscope. By integrating the mapped data in a direction parallel to the bonding interface, a one-dimensional nitrogen concentration profile was obtained perpendicular to the bonding interface. Examples of observation conditions include an acceleration voltage of 200 kV, a field magnification of 600,000x, and a field resolution of 192 pixels × 256 pixels, but the conditions are not limited to these. In this specification, the nitrogen concentration of the SiO2 film refers to the peak value of the nitrogen concentration profile of the SiO2 film.

[0105] In Example 2, two glass substrates were joined under the same joining conditions as in Example 1, except that glass substrates without chamfered edges were used as the first and second substrates. No wedge-shaped grooves were formed on the outer edge of the joining interface, and the two glass substrates could not be separated. The resulting bond was then annealed at 200°C for 2 hours. The bonding strength after annealing was measured by the crack opening method. As a result, fracture of the glass substrate occurred, indicating that the bonding strength was sufficiently high. In Example 2, the nitrogen concentration of the two SiO2 films joined together was measured by energy-dispersive X-ray analysis, and the nitrogen concentration of the SiO2 films was 1.7 atomic percent.

[0106] In Example 3, two glass substrates were joined under the same joining conditions as in Example 1, except that glass substrates made of glass B were prepared as the first and second substrates. A wedge-shaped groove was formed on the outer edge of the joining interface. This groove was formed between the chamfered surfaces. The depth of the groove was 0.28 mm. When a razor blade was inserted into the groove, the two glass substrates were separated. The two separated glass substrates were then joined again, and the resulting joint was annealed at 200°C for 2 hours. The joint strength after annealing was measured by the crack opening method. As a result, fracture of the glass substrate occurred, indicating that the joint strength was sufficiently high. In Example 3, the nitrogen concentration of the two SiO2 films joined together was measured by energy-dispersive X-ray analysis, and the nitrogen concentration of the SiO2 film was 1.7 atomic percent.

[0107] In Example 4, two glass substrates were joined under the same joining conditions as in Example 1, except that glass substrates made of glass C were prepared as the first and second substrates. A wedge-shaped groove was formed on the outer edge of the joining interface. This groove was formed between the chamfered surfaces. The depth of the groove was 280 μm. When a razor blade was inserted into the groove, the two glass substrates were separated. The two separated glass substrates were then joined again, and the resulting joint was annealed at 200°C for 2 hours. The joint strength after annealing was measured by the crack opening method. As a result, fracture of the glass substrate occurred, indicating that the joint strength was sufficiently high. In Example 4, the nitrogen concentration of the two SiO2 films joined together was measured by energy-dispersive X-ray analysis, and the nitrogen concentration of the SiO2 film was 1.9 atomic percent.

[0108] In Example 5, two glass substrates were bonded under the same bonding conditions as in Example 4, except that the SiO2 film was deposited using a sputtering method with silicon oxide as the target, rather than a reactive sputtering method with metallic silicon as the target. A wedge-shaped groove was formed on the outer edge of the bonding interface. This groove was formed between the chamfered surfaces. The depth of the groove was 0.28 mm. When a razor blade was inserted into the groove, the two glass substrates were separated. The two separated glass substrates were then bonded again, and the resulting bond was annealed at 200°C for 2 hours. The bonding strength after annealing was measured by the crack opening method. As a result, fracture of the glass substrate occurred, indicating that the bonding strength was sufficiently high. In Example 5, the nitrogen concentration of the two bonded SiO2 films was measured by energy-dispersive X-ray analysis, and the nitrogen concentration of the SiO2 film was 2.0 atomic percent.

[0109] In Example 6, a glass substrate and a sapphire substrate were joined under the same joining conditions as in Example 5, except that a sapphire substrate was prepared as the second substrate. A wedge-shaped groove was formed on the outer edge of the joining interface. This groove was formed between the chamfered surfaces. The depth of the groove was 0.28 mm. When a razor blade was inserted into the groove, the glass substrate and the sapphire substrate were separated. Subsequently, the separated glass substrate and sapphire substrate were joined again, and the resulting joint was annealed at 200°C for 2 hours. The joint strength after annealing was measured by the crack opening method. As a result, fracture of the glass substrate occurred, indicating that the joint strength was sufficiently high. In Example 6, the nitrogen concentration of the two SiO2 films joined to each other was measured by energy-dispersive X-ray analysis, and the nitrogen concentration of the SiO2 film was 2.0 atomic percent.

[0110] In Example 7, a glass substrate made of glass D was prepared as the first substrate, and a sapphire substrate was prepared as the second substrate. The glass substrate and the sapphire substrate were joined under the same bonding conditions as in Example 4. In a plan view, the glass substrate was larger than the sapphire substrate and protruded beyond the sapphire substrate. The protruding portion was grasped, and the glass substrate and sapphire substrate were separated. After that, the separated glass substrate and sapphire substrate were joined again, and the resulting joint was annealed at 200°C for 2 hours. The bonding strength after annealing was measured by the crack opening method and was 1.2 J / m 2 In Example 7, the nitrogen concentration of two bonded SiO2 films was measured by energy-dispersive X-ray spectroscopy, and the nitrogen concentration of the SiO2 film was found to be 1.7 atomic percent.

[0111] In Example 8, two glass substrates were joined under the same joining conditions as in Example 1, except that the joining surfaces of each glass substrate were modified by sequential plasma without depositing an SiO2 film on each substrate's bonding surface. A wedge-shaped groove was formed on the outer edge of the bonding interface. This groove was formed between the chamfered surfaces. The groove depth was 0.28 mm. When a razor blade was inserted into the groove, the two glass substrates were separated. The two separated glass substrates were then joined again, and the resulting bond was annealed at 200°C for 2 hours. The bonding strength after annealing was measured by the crack opening method and was 0.9 J / m 2 That was the case.

[0112] Furthermore, even when two glass substrates were joined under the same joining conditions as in Example 1, except that the joining surfaces of each glass substrate were modified with oxygen RIE alone without forming an SiO2 film on the joining surfaces of each glass substrate, the joint strength after annealing was 0.9 J / m². 2 Therefore, in the case of Example 8, that is, when the bonding surface of glass with a low SiO2 content was modified by the sequential plasma method, the bonding strength obtained was only about the same as when it was modified with oxygen RIE alone.

[0113] As is clear from comparing the evaluation results of Example 1 with those of Example 8, if at least one of the two substrates to be joined is a glass with a low SiO2 content, forming a silicon oxide film on the joining surface of that glass can improve the bonding strength using the sequential plasma method.

[0114] In Example 9, two glass substrates were joined under the same joining conditions as in Example 3, except that the joining surfaces of each glass substrate were modified by sequential plasma without depositing an SiO2 film on each substrate's bonding surface. A wedge-shaped groove was formed on the outer edge of the bonding interface. This groove was formed between the chamfered surfaces. The groove depth was 0.28 mm. When a razor blade was inserted into the groove, the two glass substrates were separated. The two separated glass substrates were then joined again, and the resulting bond was annealed at 200°C for 2 hours. The bonding strength after annealing was measured by the crack opening method and was 0.7 J / m 2 That was the case.

[0115] As is clear from comparing the evaluation results of Example 3 and Example 9, if at least one of the two substrates to be joined is a glass with a low SiO2 content, the bonding strength can be improved by the sequential plasma method if a silicon oxide film is formed on the bonding surface of that glass.

[0116] In Example 10, two glass substrates were joined under the same joining conditions as in Example 1, except that instead of depositing an SiO2 film on the bonding surface of each glass substrate, an Al2O3 film was deposited by reactive sputtering. A wedge-shaped groove was formed on the outer edge of the bonding interface. This groove was formed between the chamfered surfaces. The depth of the groove was 0.28 mm. When a razor blade was inserted into the groove, the two glass substrates were separated. The two separated glass substrates were then joined again, and the resulting bond was annealed at 200°C for 2 hours. The bonding strength after annealing was measured by the crack opening method and was 0.4 J / m 2 That was the case.

[0117] As is clear from comparing the evaluation results of Example 1 with those of Example 10, when at least one of the two substrates to be joined is a glass with a low SiO2 content, forming an aluminum oxide film on the joining surface of that glass beforehand does not improve the bonding strength using the sequential plasma method.

[0118] In Example 11, the glass substrate and the sapphire substrate were bonded under the same bonding conditions as in Example 6, except that the bonding surfaces of the glass substrate and the sapphire substrate were modified by sequential plasma without forming an SiO2 film on these bonding surfaces. A wedge-shaped groove was formed on the outer edge of the bonding interface. This groove was formed between two chamfered surfaces. The depth of the groove was 0.28 mm. When a razor blade was inserted into the groove, the glass substrate and the sapphire substrate were separated. Subsequently, the separated glass substrate and sapphire substrate were bonded again, and the resulting bond was annealed at 200°C for 2 hours. The bonding strength after annealing was measured by the crack opening method and was 0.7 J / m 2 That was the case.

[0119] As is clear from comparing the evaluation results of Example 6 with those of Example 11, if at least one of the two substrates to be joined is a glass with a low SiO2 content, forming a silicon oxide film on the joining surface of that glass can improve the bonding strength using the sequential plasma method.

[0120] In Example 12, the glass substrate and sapphire substrate were bonded under the same bonding conditions as in Example 7, except that the bonding surfaces of the glass substrate and sapphire substrate were modified by sequential plasma without depositing an SiO2 film on these surfaces. In a plan view, the glass substrate was larger than the sapphire substrate and protruded beyond the sapphire substrate. The protruding portion could be grasped and the glass substrate and sapphire substrate were separated. Subsequently, the separated glass substrate and sapphire substrate were bonded again, and the resulting bond was annealed at 200°C for 2 hours. The bond strength after annealing was measured by the crack opening method and was 0.8 J / m 2 That was the case.

[0121] As is clear from comparing the evaluation results of Example 7 and the evaluation results of Example 12, when at least one of the two base materials to be joined to each other is a glass with a low SiO2 content, it can be seen that the bonding strength can be improved by forming a silicon oxide film on the bonding surface of the glass by the sequential plasma method.

[0122] In Example 13, glass substrates made of Glass A were prepared as the first base material and the second base material. On the bonding surface of each glass substrate, a SiO2 film was formed by reactive sputtering. As the target for the reactive sputtering method, metallic silicon was used. The bonding surface of each SiO2 film was modified using oxygen plasma. Specifically, after performing irradiation of oxygen RIE, it was exposed to the atmosphere to attach OH groups. The processing time of oxygen RIE was 180 seconds. Thereafter, the two glass substrates were joined through the two modified SiO2 films. A beveled groove was formed at the outer edge of the bonding interface. The groove was formed between the chamfered surfaces. The depth of the groove was 0.28 mm. When the blade of a razor was inserted into the groove, the two glass substrates could be peeled off. Thereafter, the two peeled glass substrates were joined again, and the obtained joined body was annealed at 200 °C for 2 hours. The bonding strength after annealing was measured by the crack opening method. As a result, the bonding strength was 1.0 J / m 2 It became. In Example 13, when the nitrogen concentration of the two SiO2 films joined to each other was measured by energy dispersive X-ray analysis, nitrogen atoms were not detected in the SiO2 film.

[0123] As is clear from comparing the evaluation results of Example 1 and the evaluation results of Example 13, it can be seen that the bonding strength is improved by containing N in the SiO2 film formed on the bonding surface.

[0124] In Example 14, as shown in Figure 14, a hemispherical lens 2 (hereinafter referred to as hemispherical lens 2) was prepared as the first substrate 2. The diameter of the hemispherical lens 2 was 3 mm. A deep ultraviolet LED manufactured by DOWA Electronics was prepared as the light-emitting element 7. The light-emitting element 7 had a sapphire substrate 3 that was a square with sides of 1 mm and a thickness of 0.4 mm, and a semiconductor light-emitting layer 8 formed on the sapphire substrate 3. The semiconductor light-emitting layer 8 was connected to a submount substrate 201 made of aluminum nitride ceramics with solder 202. SiO2 films 5 and 6 were deposited on the junction surface of the light-emitting element 7 and the hemispherical lens 2 by reactive sputtering. Metallic silicon was used as the target for the reactive sputtering method. The junction surface of each SiO2 film 5 and 6 was modified by sequential plasma irradiation. Specifically, oxygen RIE, nitrogen RIE, and nitrogen radical irradiation were performed in this order, and then the surface was exposed to air to deposit OH groups. The oxygen RIE treatment time was 180 seconds, the nitrogen RIE treatment time was 180 seconds, and the oxygen radical irradiation time was 15 seconds. Subsequently, the light-emitting element 7 and the hemispherical lens 2 were bonded via the two modified SiO2 films 5 and 6. When the bonded body 1 was viewed from above, the hemispherical lens 2 was larger than the light-emitting element 7 and protruded outside the light-emitting element 7. The hemispherical lens 2 and the light-emitting element 7 were separated by holding the hemispherical lens 2 with tweezers and pulling it up perpendicular to the bonding interface. Subsequently, the separated hemispherical lens 2 and the light-emitting element 7 were bonded again, and the resulting bonded body 1 was annealed at 200°C for 2 hours. Two sets of bonded bodies 1 were prepared during this process.

[0125] In Example 14, the bonding strength between the hemispherical lens 2 and the light-emitting element 7 was measured using a die shear tester 210. The bonding strength measured using the die shear tester 210 is hereinafter referred to as the second bonding strength. The bottom surface of the submount substrate 201 was attached to the glass substrate 203 with adhesive 204 to create a sample for measuring the second bonding strength. The sample was set in the die shear tester 210, and the tip of the indenter 211 of the die shear tester 210 was shifted 0.1 mm towards the hemispherical lens 2 side (upward in Figure 14) from the bonding interface between the hemispherical lens 2 and the light-emitting element 7, while the indenter 211 was moved horizontally (to the right in Figure 14) at a speed of 0.2 mm per second. The second bonding strength is the load at which delamination occurred if delamination occurred at the bonding interface between the hemispherical lens 2 and the light-emitting element 7, and is greater than or equal to the load at which fracture occurred if fracture occurred anywhere other than the bonding interface between the hemispherical lens 2 and the light-emitting element 7. In Example 14, when the second joint strength was measured using one of the two assembled bodies 1, the solder 202 connecting the light-emitting element 7 and the submount substrate 201 broke at 2.0 kg-force. The second joint strength was 2.0 kg-force or higher.

[0126] In Example 14, using one set of bonded bodies 1 that was not used for bonding strength measurement, the nitrogen concentrations of the two bonded SiO2 films 5 and 6 were measured by energy-dispersive X-ray analysis, and the nitrogen concentration of the SiO2 films 5 and 6 was found to be 1.7 atomic percent.

[0127] In Example 15, as shown in Figure 15, the hemispherical lens 2 and the light-emitting element 7 were bonded in the same manner as in Example 14, except that the two SiO2 films 5 and 6 shown in Figure 14 were not formed before bonding. After bonding, the hemispherical lens 2 and the light-emitting element 7 could be separated by holding the hemispherical lens 2 with tweezers and pulling it up perpendicular to the bonding interface. Subsequently, the separated hemispherical lens 2 and light-emitting element 7 were bonded again, and the resulting bonded body 1 was annealed at 200°C for 2 hours. When the second bonding strength was measured after annealing, the hemispherical lens 2 and the light-emitting element 7 separated at the bonding interface with a force of 0.5 kgf. The second bonding strength was 0.5 kgf.

[0128] As is clear from comparing the evaluation results of Example 14 with those of Example 15, if at least one of the two substrates to be joined is a glass with a low SiO2 content, forming a silicon oxide film on the joining surface of that glass can improve the bonding strength using the sequential plasma method.

[0129] In Example 16, a quartz glass substrate (SiO2 substrate) was prepared as the first substrate, and a sapphire substrate was prepared as the second substrate. An SiO2 film was deposited on the bonding surface of the sapphire substrate by reactive sputtering. Metallic silicon was used as the target for the reactive sputtering method. The bonding surface of the quartz glass substrate and the bonding surface of the SiO2 film were modified by sequential plasma. Specifically, oxygen RIE, nitrogen RIE, and nitrogen radical irradiation were performed in this order, and then the surface was exposed to air to deposit OH groups. The treatment time for oxygen RIE was 180 seconds, the treatment time for nitrogen RIE was 180 seconds, and the irradiation time for nitrogen radicals was 15 seconds. After that, the quartz glass substrate and the sapphire substrate were bonded together. When the resulting bond was annealed at 200°C for 2 hours, the quartz glass substrate and the sapphire substrate had delaminated. In Example 16, |α1-α2| exceeded 4.0 ppm / °C, resulting in large thermal stress generated during annealing, which caused delamination during annealing. In Examples 1 to 15, |α1-α2| was 4.0 ppm / ℃ or less, so the thermal stress generated during annealing was small, and no delamination occurred during annealing.

[0130] The above describes the joint, the method for manufacturing the joint, and the light-emitting device related to this disclosure, but this disclosure is not limited to the above embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope described in the claims. These also naturally fall within the technical scope of this disclosure.

[0131] This application claims priority based on Japanese Patent Application No. 2020-209960, filed with the Japan Patent Office on December 18, 2020, and Japanese Patent Application No. 2021-156952, filed with the Japan Patent Office on September 27, 2021, and the entire contents of Japanese Patent Application No. 2020-209960 and Japanese Patent Application No. 2021-156952 are incorporated herein by reference. [Explanation of symbols]

[0132] 1 zygote 2 First base material 3 Second base material 4. Inorganic film 5. Silicon oxide film 6. Silicon oxide film

Claims

1. A bonded body comprising a first substrate, a second substrate, an inorganic film that bonds the first substrate and the second substrate, and a semiconductor layer formed on the surface of the second substrate opposite to the bonding surface facing the first substrate, The first substrate is SiO ２ Glass with a content of 70 mol% or less, The inorganic film includes a silicon oxide film formed on the bonding surface of the first substrate facing the second substrate. A joint having a wedge-shaped groove at the outer edge of the bonding interface between the first substrate and the second substrate.

2. The bonded body according to claim 1, wherein the thickness of the silicon oxide film formed on the bonding surface of the first substrate is 1 nm or more and 100 nm or less.

3. The second substrate is SiO ２ Glass with a content of 70 mol% or less, The bonded body according to claim 1, wherein the inorganic film comprises a first silicon oxide film formed on the bonding surface of the first substrate and a second silicon oxide film formed on the bonding surface of the second substrate.

4. The second substrate is SiO ２ An inorganic single crystal or inorganic polycrystalline material with a content of 70 mol% or less. The bonded body according to claim 1, wherein the inorganic film comprises a first silicon oxide film formed on the bonding surface of the first substrate and a second silicon oxide film formed on the bonding surface of the second substrate.

5. The bonded body according to claim 3 or 4, wherein the total thickness of the first silicon oxide film and the second silicon oxide film is 1 nm or more and 200 nm or less.

6. The bonded body according to any one of claims 1 to 5, wherein the difference in the average coefficient of linear expansion between the first substrate and the second substrate at 50°C to 200°C is 0.0 ppm / °C or more and 4.0 ppm / °C or less.

7. The bonded body according to any one of claims 1 to 6, wherein the second substrate and the semiconductor layer constitute a light-emitting element.

8. The bonded body according to claim 7, wherein the light-emitting element is an ultraviolet light-emitting element.

9. The bonded body according to claim 7 or 8, wherein the first substrate is a lens.

10. The bonded body according to claim 9, wherein the first substrate is a spherical lens with a convex surface facing away from the bonding surface of the first substrate.

11. The bonded body according to any one of claims 1 to 10, wherein the sum of the product of the Young's modulus and maximum thickness of the first substrate and the product of the Young's modulus and maximum thickness of the second substrate is between 70 GPa·mm and 300 GPa·mm.

12. The joint according to claim 11, wherein the depth of the groove is 0.05 mm to 0.5 mm.

13. The joint according to any one of claims 1 to 12, wherein, in a plan view, the first substrate is larger than the second substrate and protrudes outside the second substrate.

14. The composite according to any one of claims 1 to 13, wherein the nitrogen concentration of the silicon oxide film, as measured by energy-dispersive X-ray analysis, is 1 atomic percent or more.

15. A method for manufacturing a joint according to claim 9 or 10, A method for manufacturing a bonded body, wherein, before joining the lens and the second substrate, the bonding surface of the lens facing the second substrate is a convex curved surface, and the maximum height difference of the bonding surface of the lens is 5 nm to 400 nm.

16. A method for manufacturing a joint according to claim 9 or 10, A method for manufacturing a bonded body, wherein, before joining the lens and the second substrate, at least the portion of the bonding surface of the lens facing the second substrate that overlaps with the second substrate after bonding is a convex curved surface, and the maximum height difference of the portion is 5 nm to 200 nm.

17. A joint according to any one of claims 1 to 14, and a container for housing the joint, A light-emitting device in which the above-mentioned second substrate and the semiconductor layer constitute a light-emitting element.

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