Alkali-free glass

Abstract

To provide a glass that can suppress the deformation of a glass substrate, is excellent in moldability, and has a low burden on manufacturing equipment.SOLUTION: Provided is an alkali-free glass in which thermal expansion coefficient, Young's modulus, strain point, temperature T4 at which viscosity is 104 dPa s, glass surface devitrification temperature, and temperature T2 at which viscosity is 102 dPa s are within specified range, and contained amount of SiO2, Al2O3, B2O3, MgO, CaO, SrO, and BaO, MgO+CaO+SrO+BaO, and MgO / CaO are within specified range.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an alkali-free glass suitable for glass substrates for various displays, photomasks, electronic device supports, information recording media, planar antennas, and the like. [Background technology]

[0002] Glass plates (glass substrates) for various displays, photomasks, electronic device supports, information recording media, and flat antennas, particularly glass used for glass plates on whose surfaces thin films of metals, oxides, etc. are formed, are required to have the following properties (1) to (4). (1) When the glass contains an alkali metal oxide, the alkali metal ions diffuse into the thin film and deteriorate the film properties of the thin film, so the glass must be substantially free of alkali metal ions. (2) The glass sheet must have a high strain point so that deformation of the glass sheet and shrinkage (thermal shrinkage) associated with structural stabilization of the glass can be minimized when the glass sheet is exposed to high temperatures during the thin film formation process.

[0003] (3) Sufficient chemical resistance to the various chemicals used in semiconductor formation. x and SiN x It must be resistant to buffered hydrofluoric acid (BHF: a mixture of hydrofluoric acid and ammonium fluoride) used in etching, chemical solutions containing hydrochloric acid used in ITO etching, various acids (nitric acid, sulfuric acid, etc.) used in etching metal electrodes, and alkalis used in resist stripping solutions. (4) There are no internal or surface defects (bubbles, striae, inclusions, pits, scratches, etc.).

[0004] In addition to the above requirements, the following requirements (5) to (9) have also been made in recent years. (5) Lightweight displays are required, so glass with a low specific gravity is desirable. (6) Lighter displays are required, so thinner glass plates are desired. (7) In addition to the conventional amorphous silicon (a-Si) type LCD displays, polycrystalline silicon (p-Si) type LCD displays, which require high heat treatment temperatures, are now being manufactured (a-Si heat treatment temperature: approximately 350°C, p-Si heat treatment temperature: 350-550°C), so heat resistance is required.

[0005] (8) Glass with a small average thermal expansion coefficient is required to increase productivity by increasing the temperature rise and fall rate during heat treatment in the production of liquid crystal displays, and to improve thermal shock resistance. However, if the average thermal expansion coefficient of glass is too small, the number of film formation processes, such as those for gate metal films and gate insulating films, during the production of liquid crystal displays increases, resulting in problems such as cracks and scratches during transportation of the liquid crystal displays and significant deviations in the exposure pattern. (9) Furthermore, as glass substrates become larger and thinner, there is a demand for glass with a high specific modulus of elasticity (Young's modulus / density).

[0006] In order to satisfy the above-mentioned requirements, various glass compositions have been proposed for glass for liquid crystal display panels (see Patent Documents 1 to 4). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent No. 5702888 [Patent Document 2] International Publication No. 2013 / 183626 [Patent Document 3] Japanese Patent No. 5849965 [Patent Document 4] Japanese Patent No. 5712922 Summary of the Invention [Problem to be solved by the invention]

[0008] In recent years, electronic displays have become increasingly high-resolution, and as the definition of large-screen televisions increases, the thickness of Cu wiring, for example, increases, which makes it easier for substrates to warp due to the various film formation processes.Therefore, there is a growing need for substrates with less warpage, and to meet this need, it is necessary to increase the Young's modulus of glass. However, the known glasses with high Young's modulus as described in Patent Documents 3 and 4 have high strain points and viscosities of 10 4 The devitrification temperature tends to be higher than the temperature T4 at which the glass becomes dPa·s. As a result, it becomes difficult to mold the glass, which places a heavy load on the manufacturing equipment, raising concerns about increased production costs.

[0009] An object of the present invention is to provide glass that can suppress deformation such as warping of a glass substrate, has excellent formability, and imposes a low burden on manufacturing equipment. [Means for solving the problem]

[0010] The alkali-free glass of the present invention, which achieves the above object, has an average thermal expansion coefficient of 30×10 at 50 to 350°C. -7 ~43×10 -7 / ℃, Young's modulus is 88GPa or more, strain point is 650-725℃, viscosity is 10 4 The temperature T4 at which the glass surface becomes dPa·s is 1290°C or lower, and the glass surface devitrification temperature (T c ) is T4+20℃ or less, viscosity is 10 2 The temperature T2 at which the viscosity becomes dPa·s is 1680°C or less, In mole percent based on oxides SiO2 62-67%, Al2O3 12.5-16.5%, B2O3 0-3%, MgO 8-13%, CaO 6-12%, SrO 0.5 to 4%, Contains 0 to 0.5% BaO, MgO + CaO + SrO + BaO is 18-22%, and MgO / CaO is 0.8-1.33.

[0011] In one embodiment of the alkali-free glass of the present invention, the specific modulus of elasticity may be 34 MN·m / kg or more.

[0012] In one embodiment of the alkali-free glass of the present invention, the density is 2.60 g / cm 3 It may be the following:

[0013] In one embodiment of the alkali-free glass of the present invention, the glass surface devitrification viscosity (η c ) is 10 3.8 It may be dPa·s or more.

[0014] In one embodiment of the alkali-free glass of the present invention, the glass transition point may be 730 to 790°C.

[0015] In one embodiment of the alkali-free glass of the present invention, the value represented by the following formula (I) may be 4.10 or more. (7.87[Al2O3]-8.5[B2O3]+11.35[MgO]+7.09[CaO]+5.52[SrO]-1.45[BaO]) / [SiO2]···Equation (I)

[0016] In one embodiment of the alkali-free glass of the present invention, the value represented by the following formula (II) may be 0.95 or more. (-1.02[Al2O3] + 10.79[B2O3] + 2.84[MgO] + 4.12[CaO] + 5.19[SrO] + 3.16[BaO]) / [SiO2]···Equation (II)

[0017] In one embodiment of the alkali-free glass of the present invention, the value represented by the following formula (III) may be 5.5 or less. (8.9[Al2O3]+4.26[B2O3]+11.3[MgO]+4.54[CaO]+0.1[SrO]-9.98[BaO])×{1+([MgO] / [CaO]-1) 2} / [SiO2]...Formula (III)

[0018] In one embodiment of the alkali-free glass of the present invention, SnO2 may be contained in an amount of 0.5% or less, expressed in mole percent on an oxide basis.

[0019] In one embodiment of the alkali-free glass of the present invention, the β-OH value is 0.05 to 0.5 mm -1 may be.

[0020] In one embodiment of the alkali-free glass of the present invention, the compaction may be 100 ppm or less.

[0021] In one embodiment of the alkali-free glass of the present invention, the equivalent cooling rate may be 5 to 500° C. / min.

[0022] One embodiment of the alkali-free glass of the present invention may be a glass plate having at least one side of 1800 mm or more and a thickness of 0.7 mm or less.

[0023] An embodiment of the alkali-free glass of the present invention may be produced by a float process or a fusion process.

[0024] The display panel of the present invention comprises the alkali-free glass of the present invention.

[0025] The semiconductor device of the present invention also comprises the alkali-free glass of the present invention.

[0026] The information recording medium of the present invention comprises the alkali-free glass of the present invention.

[0027] The planar antenna of the present invention comprises the alkali-free glass of the present invention. [Effects of the Invention]

[0028] According to the present invention, it is possible to provide glass that can suppress deformation such as warping of a glass substrate, has excellent formability, and places a low burden on manufacturing equipment. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the embodiments described below. In the following, the composition range of each component of the glass is expressed in mole percent based on the oxide. In the following, the numerical range indicated as "numerical value A to numerical value B" indicates a range that includes numerical value A and numerical value B as the minimum and maximum values, respectively, and means numerical value A or more and numerical value B or less.

[0030] First, the composition of the alkali-free glass of this embodiment will be described. If the SiO2 content is less than 62 mol% (hereinafter simply referred to as %), the strain point does not rise sufficiently, and the average thermal expansion coefficient increases, tending to increase the specific gravity. Therefore, the SiO2 content is 62% or more, preferably 62.5% or more, more preferably 63% or more, particularly preferably 63.5% or more, and most preferably 64% or more. If the SiO2 content exceeds 67%, the melting property of the glass tends to decrease, the Young's modulus tends to decrease, and the devitrification temperature tends to increase. Therefore, the SiO2 content is 67% or less, preferably 66.5% or less, more preferably 66% or less, and particularly preferably 65.7% or less.

[0031] Al2O3 increases the Young's modulus, suppressing deflection, and suppresses phase separation of glass, improving fracture toughness and increasing glass strength. If the Al2O3 content is less than 12.5%, these effects are less likely to be achieved, and other components that increase the average thermal expansion coefficient will increase relatively, resulting in a tendency for the average thermal expansion coefficient to increase. Therefore, the Al2O3 content is 12.5% ​​or more, preferably 12.8% or more, and more preferably 13% or more. If the Al2O3 content exceeds 16.5%, the meltability of the glass may deteriorate, the strain point may increase, and the devitrification temperature may increase, so the Al2O3 content is 16.5% or less, preferably 16% or less, more preferably 15.7% or less, even more preferably 15% or less, particularly preferably 14.5% or less, and most preferably 14% or less.

[0032] Although B2O3 is not an essential component, it may be contained in an amount of 3% or less because it improves BHF resistance, enhances the melting reactivity of the glass, and lowers the devitrification temperature. The B2O3 content is 3% or less, preferably 2.5% or less, more preferably 2.2% or less, even more preferably 2% or less, particularly preferably 1.7% or less, and most preferably 1.5% or less.

[0033] MgO increases Young's modulus without increasing specific gravity, thereby increasing the specific elastic modulus and suppressing deflection, and also improves fracture toughness and glass strength. MgO also improves meltability. If the MgO content is less than 8%, these effects are unlikely to be achieved, and the thermal expansion coefficient may become too low. Therefore, the MgO content is 8% or more, preferably 8.2% or more, and more preferably 8.5% or more. However, if the MgO content is too high, the devitrification temperature tends to increase, so the MgO content is 13% or less, preferably 12% or less, more preferably 11% or less, even more preferably 10.5% or less, particularly preferably 10% or less, and most preferably 9.7% or less.

[0034] Among alkaline earth metals, CaO has the characteristic of increasing the specific elastic modulus second only to MgO without excessively lowering the strain point, and like MgO, it also improves solubility. Furthermore, CaO is less likely to increase the devitrification temperature than MgO. If the CaO content is less than 6%, these effects are less likely to be achieved. Therefore, the CaO content is 6% or more, preferably 7% or more, more preferably 8% or more, and even more preferably 9% or more. If the CaO content exceeds 12%, the average thermal expansion coefficient becomes too high and the devitrification temperature becomes too high, making the glass more susceptible to devitrification during production. Therefore, the CaO content is 12% or less, preferably 11% or less, and more preferably 10% or less.

[0035] SrO improves the meltability of glass without increasing the devitrification temperature, but this effect is difficult to achieve if the SrO content is less than 0.5%. Therefore, the SrO content is 0.5% or more, preferably 1% or more, more preferably 1.2% or more, and even more preferably 1.5% or more. Since SrO has a lower effect than BaO, if the SrO content is too high, the effect of increasing the specific gravity will prevail and the average thermal expansion coefficient may become too high. Therefore, the SrO content is 4% or less, preferably 3% or less, more preferably 2.5% or less, and even more preferably 2% or less.

[0036] Although BaO is not an essential component, it may be contained in the alkali-free glass of this embodiment because it improves the melting point without increasing the devitrification temperature of the glass. However, an excessive BaO content tends to increase the specific gravity, decrease the Young's modulus, and increase the average thermal expansion coefficient too much. Therefore, the BaO content is 0.5% or less. It is preferable that the alkali-free glass of this embodiment does not substantially contain BaO. In this specification, "substantially not containing" means that BaO is not contained except for unavoidable impurities mixed in from raw materials, etc., that is, BaO is not intentionally contained. In this embodiment, when BaO is substantially not contained, the BaO content is, for example, 0.3% or less, preferably 0.2% or less, more preferably 0.1% or less, even more preferably 0.05% or less, and particularly preferably 0.01% or less.

[0037] If the total amount of alkaline earth metal oxides, i.e., MgO + CaO + SrO + BaO (hereinafter also referred to as "RO"), is small, the devitrification temperature becomes high, that is, the devitrification viscosity becomes low, and formability deteriorates. Therefore, RO is set to 18% or more. If the RO content is too high, the average thermal expansion coefficient may become large and acid resistance may deteriorate, so the RO content is 22% or less, preferably 21.5% or less, more preferably 21% or less, even more preferably 20.7% or less, particularly preferably 20.5% or less, and most preferably 20.3% or less.

[0038] Furthermore, if the ratio of MgO content to CaO content, i.e., MgO / CaO, is small, CaO-Al2O3-SiO2 crystals are more likely to precipitate, resulting in poor formability. Specifically, the devitrification temperature becomes higher, i.e., the devitrification viscosity becomes lower. Therefore, MgO / CaO is 0.8 or higher, preferably 0.85 or higher, more preferably 0.9 or higher, and even more preferably 0.92 or higher. However, if the MgO / CaO ratio is too large, MgO-Al2O3-SiO2 crystals are more likely to precipitate, resulting in a higher devitrification temperature, i.e., a lower devitrification viscosity. Therefore, MgO / CaO is 1.33 or lower, preferably 1.3 or lower, more preferably 1.25 or lower, and even more preferably 1. 2 Below, especially preferred 1. 1 below, most preferably 1.0 5 Below.

[0039] The alkali-free glass of this embodiment is substantially free of alkali metal oxides such as LiO, NaO, and KO. In this embodiment, when the glass is substantially free of alkali metal oxides, the total content of alkali metal oxides is, for example, 0.5% or less, preferably 0.2% or less, more preferably 0.1% or less, more preferably 0.08% or less, even more preferably 0.05% or less, and most preferably 0.03% or less.

[0040] When the alkali-free glass plate is used in the manufacture of a display, the alkali-free glass of this embodiment preferably contains substantially no P2O5 to prevent deterioration of the properties of a thin film of metal or oxide formed on the surface of the glass plate. In this embodiment, when the alkali-free glass plate is substantially free of P2O5, the P2O5 content is, for example, 0.1% or less. Furthermore, to facilitate recycling of the glass, the alkali-free glass of this embodiment preferably contains substantially no PbO, As2O3, or Sb2O3. In this embodiment, when the alkali-free glass plate is substantially free of PbO, As2O3, or Sb2O3, the PbO, As2O3, or Sb2O3 contents are, for example, 0.01% or less, and preferably 0.005% or less.

[0041] For the purpose of improving the meltability, clarification, formability, etc. of the glass, the alkali-free glass of this embodiment may contain one or more of ZrO2, ZnO, Fe2O3, SO3, F, Cl, and SnO2 in a total amount of 2% or less, preferably 1% or less, and more preferably 0.5% or less. F is a component that improves the melting property and clarification of the glass. When F is contained in the alkali-free glass of this embodiment, the F content is preferably 1.5% or less (0.43% or less by mass). SnO2 is also a component that improves the melting property and clarification of the glass. When SnO2 is contained in the alkali-free glass of this embodiment, the SnO2 content is preferably 0.5% or less (1.1% or less by mass).

[0042] The β-OH value of the alkali-free glass of the present invention is 0.05 to 0.5 mm -1 is preferred. The β-OH value is an index of the water content in glass. The absorbance of a glass sample at wavelengths of 2.75 to 2.95 μm is measured, and the maximum absorbance value β max is calculated by dividing by the thickness (mm) of the sample. -1 If the β-OH value is less than 0.45 mm, it is easier to achieve the compaction described below. -1 Less than or equal to 0.4 mm is more preferable. -1 or less, more preferably 0.35 mm -1 or less, and more preferably 0.3 mm -1 Below 0.28 mm, particularly preferably -1 Less than or equal to 0.25 mm, most preferably -1 On the other hand, the β-OH value is 0.05 mm -1 If the β-OH value is 0.08 mm or more, it is easy to achieve the strain point of the glass described later. -1 More preferably, 0.1 mm or more is more preferable. -1 or more, and more preferably 0.13 mm -1 More than 0.15 mm, especially preferred -1 Above 0.18mm, most preferably -1 That's all.

[0043] The alkali-free glass of this embodiment preferably has a value represented by the following formula (I) of 4.10 or more. (7.87[Al2O3]-8.5[B2O3]+11.35[MgO]+7.09[CaO]+5.52[SrO]-1.45[BaO]) / [SiO2]···Equation (I) The value represented by formula (I) is an index of Young's modulus, and if this value is less than 4.10, the Young's modulus will be low. In the alkali-free glass of this embodiment, the value represented by formula (I) is more preferably 4.15 or more, even more preferably 4.2 or more, particularly preferably 4.25 or more, and most preferably 4.3 or more. In the above formula (I), [Al2O3], [B2O3], [MgO], [CaO], [SrO], [BaO], and [SiO2] respectively represent the contents of Al2O3, B2O3, MgO, CaO, SrO, BaO, and SiO2 in mole percent on an oxide basis. The same applies to the following formulas (II) and (III).

[0044] In the alkali-free glass of this embodiment, the value represented by the following formula (II) is preferably 0.95 or more. (-1.02[Al2O3] + 10.79[B2O3] + 2.84[MgO] + 4.12[CaO] + 5.19[SrO] + 3.16[BaO]) / [SiO2]···Equation (II) The value represented by formula (II) is an index of the strain point, and if this value is less than 0.95, the strain point will be high. In the alkali-free glass of this embodiment, the value represented by formula (II) is more preferably 1.0 or more, even more preferably 1.05 or more, and particularly preferably 1.1 or more.

[0045] In the alkali-free glass of this embodiment, the value represented by the following formula (III) is preferably 5.5 or less. (8.9[Al2O3]+4.26[B2O3]+11.3[MgO]+4.54[CaO]+0.1[SrO]-9.98[BaO])×{1+([MgO] / [CaO]-1) 2} / [SiO2]...Formula (III) The value represented by formula (III) is the glass surface devitrification viscosity (η c ) is an index of the glass surface devitrification viscosity (η c In the alkali-free glass of this embodiment, the value represented by formula (III) is more preferably 5.1 or less, further preferably 4.8 or less, particularly preferably 4.5 or less, and most preferably 4.3 or less.

[0046] The alkali-free glass of this embodiment has an average thermal expansion coefficient of 30×10 at 50 to 350°C. -7 / °C or more. For example, in the manufacture of a TFT-side substrate for a flat panel display, a gate metal film such as copper and a gate insulating film such as silicon nitride may be laminated in this order on an alkali-free glass substrate. In this case, the average thermal expansion coefficient at 50 to 350°C is 30 × 10 -7 If the temperature is less than 100° C. / ° C., the difference in thermal expansion between the substrate and the gate metal film made of copper or the like formed on the substrate surface will be large, which may cause problems such as substrate warping and film peeling. The average thermal expansion coefficient between 50 and 350°C is 33 x 10 -7 / ℃ or more is preferable, 35 × 10 -7 / ℃ or more is more preferable, and 36×10 -7 / °C or more is more preferable, and 37 × 10 -7 / °C or higher, most preferably 38 x 10 -7 / ℃ or more. On the other hand, the average thermal expansion coefficient between 50 and 350°C is 43×10 -7 If the temperature exceeds 50°C / °F, the glass may break during the manufacturing process of products such as displays. Therefore, the average thermal expansion coefficient between 50 and 350°C is 43×10 -7 / ℃ or less. The average thermal expansion coefficient between 50 and 350°C is 42 x 10 -7 / ℃ or less is preferable, and 41.5 × 10 -7 / ℃ or less is more preferable, and 41×10 -7 / °C or less is more preferable, and 40.5 × 10 -7 / °C or less is particularly preferable, and 40.3 × 10 -7 / °C or less is most preferable.

[0047] The alkali-free glass of this embodiment has a Young's modulus of 88 GPa or more. This suppresses deformation of the substrate due to external stress. For example, warping of the substrate can be suppressed when a film is formed on the surface of the glass substrate. As a specific example, in the manufacture of a TFT-side substrate for a flat panel display, warping of the substrate is suppressed when a gate metal film such as copper or a gate insulating film such as silicon nitride is formed on the surface of the substrate. Furthermore, deflection when the substrate size is increased, for example, is also suppressed. The Young's modulus is preferably 88.5 GPa or more, more preferably 89 GPa or more, even more preferably 89.5 GPa or more, particularly preferably 90 GPa or more, and most preferably 90.5 GPa or more. The Young's modulus can be measured by an ultrasonic method.

[0048] The alkali-free glass of this embodiment has a strain point of 650 to 725°C. If the strain point is less than 650°C, deformation of the glass plate and shrinkage (thermal shrinkage) associated with structural stabilization of the glass are likely to occur when the glass plate is exposed to high temperatures during the thin film formation process for displays. The strain point is preferably 685°C or higher, more preferably 690°C or higher, even more preferably 693°C or higher, particularly preferably 695°C or higher, and most preferably 698°C or higher. On the other hand, if the strain point is too high, the temperature of the annealing apparatus must be increased accordingly, which tends to shorten the life of the annealing apparatus. The strain point is preferably 723°C or lower, more preferably 720°C or lower, even more preferably 718°C or lower, particularly preferably 716°C or lower, and most preferably 714°C or lower.

[0049] The alkali-free glass of this embodiment has a viscosity of 10 4The temperature T4 at which the viscosity reaches dPa·s is 1290°C or lower. This provides the alkali-free glass of this embodiment with excellent formability. This also makes it possible, for example, to lower the temperature during forming of the glass of this embodiment, thereby reducing volatile substances in the atmosphere surrounding the glass and thereby reducing defects. Furthermore, this allows the glass to be formed at a lower temperature, thereby reducing the burden on manufacturing equipment. For example, the life of a float bath used to form the glass can be extended, improving productivity. T4 is preferably 1287°C or lower, more preferably 1285°C or lower, even more preferably 1283°C or lower, and particularly preferably 1280°C or lower. T4 is measured using a rotational viscometer according to the method specified in ASTM C 965-96, and the viscosity is 10 4 It can be calculated as the temperature at which the viscosity becomes d·Pa·s. In the examples described later, NBS710 and NIST717a were used as reference samples for calibrating the instrument.

[0050] The alkali-free glass of this embodiment has a glass surface devitrification temperature (T c ) is T4+20°C or less. This provides the alkali-free glass of this embodiment with excellent formability. This also makes it possible to suppress the formation of crystals inside the glass during forming, which would otherwise cause a decrease in transmittance. This also makes it possible to reduce the burden on manufacturing equipment. For example, this makes it possible to extend the life of float baths used to form glass, thereby improving productivity. Glass surface devitrification temperature (T c ) is preferably T4+10°C or lower, more preferably T4+5°C or lower, even more preferably T4°C or lower, particularly preferably T4-1°C or lower, and most preferably T4-5°C or lower. Glass surface devitrification temperature (T c ) and glass internal devitrification temperature (T d The glass surface devitrification temperature (T) can be calculated as follows: crushed glass particles are placed in a platinum dish and heat-treated for 17 hours in an electric furnace controlled at a constant temperature. After the heat treatment, an optical microscope is used to measure the maximum temperature at which crystals precipitate on the glass surface and the minimum temperature at which crystals do not precipitate. The average of these values ​​is taken as the glass surface devitrification temperature (T). cSimilarly, the maximum temperature at which crystals precipitate inside the glass and the minimum temperature at which crystals do not precipitate are measured, and the average value is taken as the glass internal devitrification temperature (T d ) The glass surface devitrification temperature (T c ) and glass internal devitrification temperature (T d The viscosity at each devitrification temperature is obtained by measuring the viscosity of the glass at each devitrification temperature.

[0051] The specific elastic modulus (Young's modulus (GPa) / density (g / cm 3 ) is preferably 34 MN·m / kg or more. This reduces the self-weight deflection, making it easier to handle when made into a large substrate. The specific modulus is more preferably 34.5 MN·m / kg or more, even more preferably 34.8 MN·m / kg or more, particularly preferably 35 MN·m / kg or more, and most preferably 35.2 MN·m / kg or more. Note that a large substrate is, for example, a substrate with at least one side of 1800 mm or more. At least one side of the large substrate may be, for example, 2000 mm or more, 2500 mm or more, 3000 mm or more, or 3500 mm or more.

[0052] The density of the alkali-free glass of this embodiment is 2.60 g / cm 3 The density is preferably 2.59 g / cm or less. This reduces the deflection due to its own weight, making it easier to handle when made into a large substrate. In addition, the weight of a device using the alkali-free glass of this embodiment can be reduced. 3 Less than 2.58 g / cm is more preferable. 3 More preferably, 2.57 g / cm 3 The following is particularly preferred: 2.56 g / cm 3 The following are most preferred:

[0053] The glass surface devitrification temperature (T c The glass surface devitrification viscosity (η c ) is 10 3.8dPa·s or more is preferable. This results in excellent formability of the glass substrate. This also makes it possible to suppress the occurrence of crystals inside the glass during forming, which would otherwise cause a decrease in transmittance. This also reduces the burden on manufacturing equipment. For example, it is possible to extend the life of float baths used to form glass substrates, thereby improving productivity. Glass surface devitrification viscosity (η c ) is preferably 10 3.85 dPa·s or more, more preferably 10 3.9 dPa·s or more, particularly preferably 10 4 dPa·s or more, most preferably 10 4.05 It is dPa·s or more.

[0054] The viscosity of the alkali-free glass of this embodiment is 10 2 The temperature T2 at which the melting point reaches dPa·s is preferably 1680°C or lower. This results in excellent glass melting properties. This also reduces the burden on manufacturing equipment. For example, the life of a glass melting furnace can be extended, improving productivity. This also reduces furnace-related defects (e.g., lumpy defects, Zr defects, etc.). T2 is more preferably 1670°C or lower, even more preferably 1660°C or lower, particularly preferably 1640°C or lower, particularly preferably 1635°C or lower, and most preferably 1625°C or lower.

[0055] The alkali-free glass of this embodiment preferably has a glass transition point of 730 to 790°C. A glass transition point of 730°C or higher results in excellent glass formability. For example, thickness deviation and surface waviness can be reduced. Furthermore, a glass transition point of 790°C or lower can reduce the burden on manufacturing equipment. For example, the surface temperature of the rolls used in glass forming can be lowered, thereby extending the life of the equipment and improving productivity. The glass transition point is more preferably 740°C or higher, even more preferably 745°C or higher, particularly preferably 750°C or higher, and most preferably 755°C or higher. On the other hand, the glass transition point is more preferably 785°C or lower, even more preferably 783°C or lower, particularly preferably 780°C or lower, and most preferably 775°C or lower.

[0056] The compaction of the alkali-free glass of this embodiment is preferably 100 ppm or less, more preferably 90 ppm or less, even more preferably 80 ppm or less, even more preferably 75 ppm or less, particularly preferably 70 ppm or less, and most preferably 65 ppm or less. Compaction is the thermal shrinkage rate of glass that occurs due to relaxation of the glass structure during heat treatment. If the compaction is 100 ppm or less, it is possible to minimize dimensional changes associated with glass deformation and glass structural stabilization when exposed to high temperatures in the thin film formation process carried out in the manufacture of various displays. In this embodiment, compaction refers to compaction measured in the following procedure. A glass plate sample (100 mm long x 10 mm wide x 1 mm thick, mirror-polished with cerium oxide) obtained by processing the alkali-free glass of this embodiment is held at a temperature of glass transition point + 120°C for 5 minutes, and then cooled to room temperature at 40°C per minute. Once the glass plate sample has cooled to room temperature, the total length (longitudinal direction) L1 of the sample is measured. The glass plate sample is then heated to 600°C at 100°C per hour, held at 600°C for 80 minutes, and cooled to room temperature at 100°C per hour. Once the glass plate sample has cooled to room temperature, the total length L2 of the sample is measured again. The ratio (L1-L2) / L1 of the difference in total length before and after heat treatment at 600°C to the total length L1 of the sample before heat treatment at 600°C is taken as the compaction value.

[0057] In order to reduce compaction, the alkali-free glass of this embodiment preferably has an equivalent cooling rate of 500°C / min or less. From the viewpoint of the balance between compaction and productivity, the equivalent cooling rate is preferably 5°C / min or more and 500°C / min or less. From the viewpoint of productivity, the equivalent cooling rate is more preferably 10°C / min or more, even more preferably 15°C / min or more, particularly preferably 20°C / min or more, and most preferably 25°C / min or more. From the viewpoint of compaction, the equivalent cooling rate is more preferably 300°C / min or less, even more preferably 200°C / min or less, particularly preferably 150°C / min or less, and most preferably 100°C / min or less. The equivalent cooling rate in this embodiment means an equivalent cooling rate measured by the following procedure. A number of rectangular parallelepiped samples for creating a calibration curve, each measuring 10 mm x 10 mm x 1 mm, were prepared by processing the alkali-free glass of this embodiment, and these were held at the glass transition point +120°C for 5 minutes using an infrared heating electric furnace. Each sample was then cooled to 25°C at different cooling rates ranging from 1°C / min to 1000°C / min. Next, the refractive indexes n of the d line (wavelength 587.6 nm) of these samples were measured using a precision refractometer KPR-2000 manufactured by Shimadzu Devices Corporation. d is measured by the V-block method. d By plotting against the logarithm of the cooling rate, the relationship between the cooling rate and n d Obtain a calibration curve. Next, the alkali-free glass of this embodiment was processed into a rectangular parallelepiped shape of 10 mm × 10 mm × 1 mm, and d is measured by the V-block method using a precision refractometer KPR-2000 manufactured by Shimadzu Devices Co., Ltd. d The cooling rate corresponding to the above is determined from the calibration curve and is used as the equivalent cooling rate.

[0058] The alkali-free glass of this embodiment has a high Young's modulus of 88 GPa or more, which suppresses deformation of the substrate due to external stress, making it suitable for use as a glass plate used as a large substrate. A large substrate is, for example, a glass plate with at least one side of 1800 mm or more, and a specific example is a glass plate with a long side of 1800 mm or more and a short side of 1500 mm or more. The alkali-free glass of the present embodiment is more preferably a glass plate having at least one side of 2400 mm or more, for example, a glass plate having a long side of 2400 mm or more and a short side of 2100 mm or more, more preferably a glass plate having at least one side of 3000 mm or more, for example, a glass plate having a long side of 3000 mm or more and a short side of 2800 mm or more, particularly preferably a glass plate having at least one side of 3200 mm or more, for example, a glass plate having a long side of 3200 mm or more and a short side of 2900 mm or more, and most preferably a glass plate having at least one side of 3300 mm or more, for example, a glass plate having a long side of 3300 mm or more and a short side of 2950 mm or more. The alkali-free glass of this embodiment preferably has a thickness of 0.7 mm or less to achieve light weight. The thickness of the alkali-free glass of this embodiment is more preferably 0.65 mm or less, even more preferably 0.55 mm or less, preferably 0.45 mm or less, and most preferably 0.4 mm or less. The thickness can be 0.1 mm or less, or even 0.05 mm or less, but from the viewpoint of preventing deflection under its own weight, the thickness is preferably 0.1 mm or more, more preferably 0.2 mm or more.

[0059] The alkali-free glass of this embodiment can be produced, for example, by the following procedure. Glass raw materials are mixed to obtain a desired glass composition, charged into a melting furnace, and heated to 1500 to 1800°C to melt the mixture to obtain molten glass. The resulting molten glass is formed into a glass ribbon of a predetermined thickness in a forming device, and the glass ribbon is slowly cooled and then cut to obtain alkali-free glass. In the production of the alkali-free glass of this embodiment, in order to reduce compaction, it is preferable to cool the glass so that the equivalent cooling rate is 500° C. / min or less, for example.

[0060] In the production of the alkali-free glass of this embodiment, it is preferable to form molten glass into a glass plate by a float process, a fusion process, etc. From the viewpoint of stably producing large plate glass having a high Young's modulus (for example, one side of 1800 mm or more), it is preferable to use the float process.

[0061] Next, the display panel of this embodiment will be described. The display panel of this embodiment has the alkali-free glass of this embodiment as a glass substrate. The display panel is not particularly limited as long as it has the alkali-free glass of this embodiment, and may be any of various display panels such as a liquid crystal display panel or an organic EL display panel. Taking the case of a thin-film transistor liquid crystal display (TFT-LCD) as an example, it has a display surface electrode substrate (array substrate) on whose surface gate electrode lines and a gate insulating oxide layer are formed, and further, pixel electrodes are formed on the surface of the oxide layer, and a color filter substrate on whose surface RGB color filters and counter electrodes are formed, and a cell is formed by sandwiching a liquid crystal material between the paired array substrate and color filter substrate. In addition to such a cell, a liquid crystal display panel also includes other elements such as peripheral circuits. The liquid crystal display panel of this embodiment uses the alkali-free glass of this embodiment for at least one of the pair of substrates that make up the cell.

[0062] The alkali-free glass of this embodiment can be used, for example, as a glass plate for supporting an electronic device. When the alkali-free glass of this embodiment is used as a glass plate for supporting an electronic device, a device-forming substrate such as a glass substrate, a silicon substrate, or a resin substrate is supported by being bonded directly or using an adhesive to the alkali-free glass of this embodiment (glass plate for supporting an electronic device). Examples of glass plates for supporting electronic devices include supporting glass plates in the manufacturing process of flexible displays (e.g., organic EL displays) using resins such as polyimide as substrates, and supporting glass plates for resin-silicon chip composite wafers in the manufacturing process of semiconductor packages.

[0063] Next, the semiconductor device of this embodiment will be described. The semiconductor device of this embodiment has the alkali-free glass of this embodiment as a glass substrate. Specifically, the semiconductor device of this embodiment has the alkali-free glass of this embodiment as a glass substrate for image sensors such as MEMS, CMOS, and CIS. The semiconductor device of this embodiment also has the alkali-free glass of this embodiment as a cover glass for a display device used for projection, for example, a cover glass for LCOS (Liquid Crystal on Silicon).

[0064] Next, the information recording medium of this embodiment will be described. The information recording medium of this embodiment has the alkali-free glass of this embodiment as a glass substrate. Specific examples of the information recording medium include magnetic recording media and optical disks. Examples of the magnetic recording medium include energy-assisted magnetic recording media and perpendicular magnetic recording magnetic recording media.

[0065] Next, the planar antenna of this embodiment will be described. The planar antenna of this embodiment has the alkali-free glass of this embodiment as a glass substrate. Specific examples of the planar antenna of this embodiment include planar liquid crystal antennas having a planar shape, such as liquid crystal antennas and microstrip antennas (patch antennas), which have good directivity and reception sensitivity. Liquid crystal antennas are disclosed, for example, in International Publication No. 2018 / 016398. Patch antennas are disclosed, for example, in Japanese Patent Application Laid-Open No. 2017-509266 and Japanese Patent Application Laid-Open No. 2017-063255. [Example]

[0066] Examples will be described below, but the present invention is not limited to these Examples. In the following, Examples 1 to 12 and Examples 19 to 36 are Examples, and Examples 13 to 18 are Comparative Examples. The raw materials for each component were mixed so that the glass composition would be the composition shown in Tables 1 to 6 (unit: mol %), and melted in a platinum crucible at 1600°C for 1 hour. After melting, the molten liquid was poured onto a carbon plate and held at a temperature of the glass transition point + 30°C for 60 minutes, after which it was cooled at 1°C per minute to room temperature (25°C) to obtain a plate-shaped glass. This was mirror-polished to obtain a glass plate, and various physical properties were measured. The results are shown in Tables 1 to 6. In Tables 1 to 6, the values ​​shown in parentheses are calculated values, and blanks indicate unmeasured values.

[0067] The methods for measuring each physical property are shown below. (average thermal expansion coefficient) Measurements were made using a differential thermal dilatometer (TMA) according to the method specified in JIS R3102 (1995). The measurement temperature range was from room temperature to 400°C or higher, and the average thermal expansion coefficient in the range of 50 to 350°C was calculated in units of 10. -7 The temperature was expressed as / °C. (density) According to the method specified in JIS Z 8807, the density of about 20 g of glass mass containing no bubbles was measured by the Archimedes method.

[0068] (distortion point) The strain point was measured by the fiber stretching method according to the method specified in JIS R3103-2 (2001). (glass transition temperature Tg) The glass transition temperature Tg was measured by the thermal expansion method according to the method specified in JIS R3103-3 (2001). (Young's modulus) In accordance with the method specified in JIS Z 2280, the Young's modulus was measured by the ultrasonic pulse method for glass having a thickness of 0.5 to 10 mm.

[0069] (T2) The viscosity was measured using a rotational viscometer according to the method specified in ASTM C 965-96. 2 The temperature T2 (°C) at which the viscosity reached d·Pa·s was measured. (T4) The viscosity was measured using a rotational viscometer according to the method specified in ASTM C 965-96. 4 The temperature T4 (°C) at which the viscosity reached d·Pa·s was measured. (devitrification temperature) The glass was crushed and classified using a test sieve to obtain particles with a particle size ranging from 2 to 4 mm. The resulting glass cullet was ultrasonically cleaned in isopropyl alcohol for 5 minutes, washed with ion-exchanged water, dried, placed in a platinum dish, and heat-treated in a temperature-controlled electric furnace for 17 hours. The heat treatment temperature was set at 10°C intervals. After the heat treatment, the glass was removed from the platinum dish, and the maximum temperature at which crystals precipitated on the surface and inside of the glass and the minimum temperature at which no crystals precipitated were measured using an optical microscope. The maximum temperature at which crystals precipitated on the surface and inside of the glass and the minimum temperature at which no crystals precipitated were each measured once (when it was difficult to determine whether crystals precipitated, the measurements were taken twice). The average value of the maximum temperature at which crystals precipitate on the glass surface and the minimum temperature at which crystals do not precipitate is calculated to determine the glass surface devitrification temperature (T c Similarly, the average value of the maximum temperature at which crystals precipitate inside the glass and the minimum temperature at which crystals do not precipitate was calculated to obtain the glass internal devitrification temperature (T d ) was decided.

[0070] (specific elastic modulus) The specific elastic modulus was calculated by dividing the Young's modulus obtained by the above-mentioned procedure by the density. (devitrification viscosity) The glass surface devitrification temperature (T c ) and the glass surface devitrification temperature (T c ) and measure the glass surface devitrification viscosity (η c Similarly, the internal devitrification temperature (T d ) and the glass internal devitrification temperature (T d ) and measure the glass internal devitrification viscosity (η d ) was decided.

[0071] [Table 1]

[0072] [Table 2]

[0073] [Table 3]

[0074] [Table 4]

[0075] [Table 5]

[0076] [Table 6]

[0077] Example 13, in which Al2O3 was less than 12.5%, B2O3 was more than 3%, MgO was less than 8%, CaO was less than 6%, SrO was more than 4%, RO was less than 18, and MgO / CaO was more than 1.33, had a low Young's modulus of less than 88 GPa and a high T4 of more than 1290°C. Example 14, in which Al2O3 was less than 12.5% ​​and SrO was 0%, had a low glass surface devitrification temperature (T c ) was higher than T4+20°C. Examples 15, 17, and 18, in which the value of formula (II) was less than 0.95, had high strain points exceeding 725°C. Example 16, in which SiO2 was less than 62%, Al2O3 was less than 12.5%, MgO was more than 13%, CaO was more than 12%, SrO was 0%, and RO was more than 22%, had a high average thermal expansion coefficient of 43 × 10 -7 / ℃.

[0078] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application (Patent Application No. 2018-46960) filed on March 14, 2018, the entirety of which is incorporated by reference. All references cited herein are incorporated in their entirety. [Industrial Applicability]

[0079] The alkali-free glass of the present invention having the above-mentioned characteristics is suitable for applications such as display substrates, photomask substrates, electronic device support substrates, information recording medium substrates, and flat antenna substrates.

Claims

1. SiO ２ The main component is Al ２ O ３ and B ２ O ３ An alkali-free glass containing In mole percent based on oxides SiO ２ 62 to 67% Al ２ O ３ を12.5~15%、 MgO 9 to 13%, CaO 6 to 12%, SrO 0.5 to 2.5%, Contains 0 to 0.5% BaO, MgO+CaO+SrO+BaO is 18 to 22%; MgO / CaO is 0.8 or more, The strain point is 685 to 725°C, Average thermal expansion coefficient between 50 and 350°C is 30 x 10 －７ ~43 x 10 －７ / °C, Viscosity is 10 ２ Temperature T at which viscosity becomes dPa s ２ is 1680°C or less, Viscosity is 10 ４ Temperature T when it becomes d Pa s ４ (°C) is 1290°C or less, Glass surface devitrification temperature (T ｃ ) is T ４ +20°C or less, The specific elastic modulus is 34 MN m / kg or more, An alkali-free glass characterized in that the value represented by the following formula (II) is 1.0 or more. (-1.02[All ２ Oh ３ ]+10.79[LN ２ Oh ３ ]+2.84[MgO]+4.12[1O]+5.19[SrO]+3.16[BaO]) / [SiO ２ ]・・・form (-I)

2. Density is 2.60 g / cm ３ The alkali-free glass according to claim 1, wherein:

3. Glass surface devitrification viscosity (η ｃ ) is 10 ３．８ The alkali-free glass according to claim 1 or 2, having a viscosity of dPa·s or more.

4. The alkali-free glass according to any one of claims 1 to 3, which has a glass transition point of 730 to 790°C.

5. The alkali-free glass according to any one of claims 1 to 4, wherein the value represented by the following formula (I) is 4.60 or less: (7.87[All ２ Oh ３ ]-8.5[B ２ Oh ３ ]+11.35[MO]+7.09[1O]+5.52[SrO]-1.45[BaO]) / [SiO ２ ]・・・form (I)

6. The alkali-free glass according to any one of claims 1 to 5, wherein the value represented by the following formula (II) is 1.17 or more:

7. The alkali-free glass according to any one of claims 1 to 6, wherein the value represented by the following formula (III) is 4.09 to 4.8: (8.9 [Al ２ O ３ + 4.26 [B ２ O ３ + 11.3 [MgO] + 4.54 [CaO] + 0.1 [SrO] - 9.98 [BaO]) × {1 + ([MgO] / [CaO] - 1) ２} / [SiO ２ ··· Formula (III)

8. In mole percent based on oxide, SnO ２ The alkali-free glass according to any one of claims 1 to 7, containing 0.5% or less of

9. β-OH value: 0.05 to 0.5 mm －１ The alkali-free glass according to any one of claims 1 to 8, wherein

10. The alkali-free glass according to any one of claims 1 to 9, which has a compaction of 100 ppm or less.

11. The alkali-free glass according to any one of claims 1 to 10, having an equivalent cooling rate of 5 to 500°C / min.

12. The alkali-free glass according to any one of claims 1 to 11, which is a glass plate having at least one side measuring 1800 mm or more and a thickness of 0.7 mm or less.

13. The alkali-free glass of claim 12 produced by a float process or a fusion process.

14. A display panel comprising the alkali-free glass according to any one of claims 1 to 13.

15. A semiconductor device comprising the alkali-free glass according to any one of claims 1 to 13.

16. An information recording medium comprising the alkali-free glass according to any one of claims 1 to 13.

17. A planar antenna comprising the alkali-free glass according to any one of claims 1 to 13.

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