Glass substrate, black matrix substrate and display panel

Abstract

The present invention relates to a glass substrate, a black matrix substrate, and a display panel. The present invention relates to a glass substrate having a pair of main surfaces and an end surface, wherein, when the Sn atomic concentration in a region from a depth of 0.1 μm to a depth of 0.3 μm from the main surface is defined as the Sn atomic concentration in the surface portion of the glass substrate, and the Sn atomic concentration in a region from a depth of 9.0 μm to a depth of 9.2 μm from the main surface is defined as the Sn atomic concentration in the interior of the glass substrate, in at least one main surface, the surface-diffused Sn atomic concentration obtained by subtracting the Sn atomic concentration in the interior of the glass substrate from the Sn atomic concentration in the surface portion of the glass substrate is 2.0×10 18 atoms / cm 3 Above and 1.4×10 19 atoms / cm 3 the following.

Description

[0001] This application is a divisional application of the Chinese patent application with application date of August 29, 2019 and application number 201980060611.6. Technical Field

[0002] The present invention relates to a glass substrate and also to a black matrix substrate having a black matrix film formed on the surface of the glass substrate and a display panel having the black matrix substrate. Background Art

[0003] Glass substrates are widely used as substrates for flat panel displays such as liquid crystal displays and organic EL displays, solar cells, and organic EL lighting. In these applications, films such as films made of resin materials (hereinafter also referred to as resin films) are formed on the glass substrates to improve display properties and other characteristics.

[0004] However, since the interaction between the film and the glass substrate is weak, the adhesion is sometimes insufficient, and the film may partially peel off from the glass substrate during the production process, resulting in reduced production yield, increased management time, and increased manufacturing costs.

[0005] To solve such problems, methods of imparting organic functional groups to glass substrates or forming coatings are used to improve adhesion by, for example, improving the interaction between the resin material and the glass substrate (Patent Documents 1 to 4).

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2000-221485

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2000-302487

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2001-192235

[0011] Patent Document 4: International Publication No. 2014 / 163035 Summary of the Invention

[0012] Problems to be solved by the invention

[0013] However, with the increasing precision of flat panel displays, the film formed on the surface of the glass substrate is required to form a finer pattern, which requires higher adhesion between the film and the glass substrate. Furthermore, a glass substrate that can reduce the burden of management and cost during manufacturing is required.

[0014] Therefore, an object of the present invention is to provide a glass substrate having excellent adhesion to a film formed on the surface of the glass substrate and high production efficiency.

[0015] Means used to solve problems

[0016] The present inventors have discovered that a glass substrate having a Sn concentration in at least one main surface above a specific range has high adhesion to a film formed on the surface of the glass substrate and excellent productivity, thereby completing the present invention.

[0017] That is, one embodiment of the present invention is a glass substrate having a pair of main surfaces and an end surface, wherein:

[0018] When the Sn atomic concentration in the region of 0.1 μm to 0.3 μm from the main surface is defined as the Sn atomic concentration in the surface layer of the glass substrate, and the Sn atomic concentration in the region of 9.0 μm to 9.2 μm from the main surface is defined as the Sn atomic concentration in the interior of the glass substrate,

[0019] In at least one main surface, the surface-diffused Sn atomic concentration obtained by subtracting the Sn atomic concentration inside the glass substrate from the Sn atomic concentration in the surface portion of the glass substrate is 2.0×10 18 atoms / cm 3 Above and 1.4×10 19 atoms / cm 3 the following.

[0020] In the glass substrate according to one embodiment of the present invention, it is preferred that: in the at least one main surface, the Sn atomic concentration gradient in the surface layer of the glass substrate is -1.0×10 23 atoms / cm 4 Above and -1.0×10 22 atoms / cm 4 The Sn atomic concentration gradient in the surface layer of the glass substrate refers to the concentration gradient of Sn atoms in the depth of 0.1 μm to 0.5 μm (0.1×10 -4 cm~0.5×10 -4 The Sn atomic concentration (atoms / cm) in the area 3 ) is the slope of a linear function obtained by linearly approximating the depth distribution of .

[0021] The glass substrate of one embodiment of the present invention preferably includes alkali-free glass, and expressed in mole % based on oxides, the alkali-free glass contains: 50% to 75% SiO2, 7% to 25% Al2O3, and 0.1% to 12% B2O3, and the total content of MgO, CaO, SrO and BaO is 7% to 25%.

[0022] In the glass substrate of one embodiment of the present invention, it is preferred that the strain point of the alkali-free glass is 650° C. or higher, and the average thermal expansion coefficient of the alkali-free glass at 50° C. to 350° C. is 30×10 -7 / ℃~45×10 -7 / ℃.

[0023] In the glass substrate according to one embodiment of the present invention, it is preferred that the alkali metal oxide content in the alkali-free glass be 0.5% or less, expressed as mol% based on oxides.

[0024] The glass substrate according to one embodiment of the present invention is preferably produced by a float process.

[0025] In the glass substrate according to one embodiment of the present invention, it is preferable that the at least one main surface is a polished surface formed by polishing.

[0026] In the glass substrate of one embodiment of the present invention, the polished surface preferably has a texture direction index (Stdi value) of 0.75 or less. The Stdi value is a parameter calculated by performing a roughness analysis on a shape image obtained using an atomic force microscope (AFM) in a 1 μm × 1 μm square observation field and 256 × 256 pixels, performing a leveling process using image analysis software (e.g., SPIP, manufactured by Image Metrology).

[0027] One embodiment of the present invention is a black matrix substrate including a black matrix film formed on at least one of the main surfaces of the glass substrate.

[0028] One embodiment of the present invention is a display panel including the black matrix substrate.

[0029] Effects of the Invention

[0030] The surface-diffused Sn atoms in the glass substrate of the present invention are Sn atoms diffused from the exterior of the glass substrate and are primarily present as divalent Sn atoms. It is believed that by achieving a surface-diffused Sn atom concentration above a specific range, the glass substrate of the present invention has divalent Sn atoms present above a specific range in the surface portion of the glass substrate, thereby improving the adhesion between the glass substrate and a film. Therefore, the glass substrate of the present invention exhibits excellent adhesion between the glass substrate and a film, enabling the formation of finer patterns when patterning a film such as a resin. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1(a) is a graph showing the relationship between the residual resolution and the Sn atomic concentration inside the glass substrate.

[0032] Figure 1 (b) is a graph showing the relationship between the residual resolution and the concentration of Sn atoms diffused in the surface layer. DETAILED DESCRIPTION

[0033] <Glass Substrate>

[0034] The glass substrate according to one embodiment of the present invention is described in detail below. Throughout this specification, the term "to" (from) used to denote a numerical range includes both preceding and following numerical values ​​as lower and upper limits. Unless otherwise specified, "to" has the same meaning throughout this specification. Furthermore, unless otherwise specified, the content of each component in a glass composition is expressed as a molar percentage based on the oxide.

[0035] The glass substrate of the present invention is a glass substrate having a pair of main surfaces and an end surface, and is characterized in that the surface layer diffused Sn atomic concentration is 2.0×10 18 atoms / cm 3 Above and 1.4×10 19 atoms / cm 3 The surface-diffused Sn atomic concentration is determined as follows: the Sn atomic concentration in the region from a depth of 0.1 μm to a depth of 0.3 μm from the main surface is defined as the Sn atomic concentration in the surface portion of the glass substrate, and the Sn atomic concentration in the region from a depth of 9.0 μm to a depth of 9.2 μm from the main surface is defined as the Sn atomic concentration in the interior of the glass substrate. In at least one main surface, the Sn atomic concentration in the interior of the glass substrate is subtracted from the Sn atomic concentration in the surface portion of the glass substrate.

[0036] In the top layer of glass substrate, Sn atom concentration is high, such as in the soda-lime glass of float forming, the valence of the Sn atom in the top layer of glass substrate is divalent, on the other hand, the valence of the Sn atom in the inside of glass substrate is tetravalent [G.H. Frischat, C. Muller-Fildebrandt, D. Moseler, G. Heide, J. Non-Cryst. Solids 283 (2001) 246-249.]. Therefore, it is believed that the high concentration of Sn atom in the top layer of glass substrate is the Sn atom diffused from the outside of glass substrate, mainly exists in the form of divalent Sn atom. The divalent Sn atom diffuses into the film of the resin etc. formed on the surface of glass substrate, thereby improving the adhesion of glass substrate and the film. On the other hand, because the tetravalent Sn atom functions as a network formation thing in glass, it is believed that it will not diffuse into the film.

[0037] In the glass substrate of one embodiment of the present invention, the surface layer of the glass substrate is diffused with Sn atoms at a concentration of 2.0×10 18 atoms / cm 3 As described above, the divalent Sn atoms diffuse into the film of resin or the like formed on the glass substrate, thereby improving the adhesion to the film. When the film is patterned, a finer pattern can be formed. The surface-diffused Sn atom concentration of the glass substrate of one embodiment of the present invention is preferably 2.5×10 18 atoms / cm 3 More preferably, 3.0×10 18 atoms / cm 3 Above, particularly preferably 4.0×10 18 atoms / cm 3 More than, most preferably 5.0×10 18 atoms / cm 3 above.

[0038] It should be noted that the surface-diffused Sn atoms in the glass substrate of the present invention are Sn atoms diffused from the outside of the glass substrate and exist primarily in the form of divalent Sn atoms. It is believed that these divalent Sn atoms improve the adhesion between the glass substrate and the film. Therefore, when patterning a film such as a resin, the glass substrate of the present invention can form a finer pattern.

[0039] On the other hand, when the surface diffusion Sn atomic concentration is greater than 1.4×10 19 atoms / cm 3 When Sn atoms are present in the device manufacturing process using the glass substrate, they may cause fluorescence and cause problems. For example, in the laser annealing process, which is one of the TFT processes, Sn atoms absorb the irradiation light of the excimer laser with a wavelength of 308nm and produce fluorescence, which may significantly reduce the TFT characteristics. The surface diffusion Sn atom concentration of the glass substrate in one embodiment of the present invention is preferably 1.2×10 19 atoms / cm 3 Below, more preferably 1.1×10 19 atoms / cm 3 Below, particularly preferably 9.5×10 18 atoms / cm 3 Below, the most preferred is 8.9×10 18 atoms / cm 3 the following.

[0040] The Sn atomic concentrations in the surface and interior of the glass substrate and the concentration gradient of Sn atoms in the surface can be determined by the Sn atomic concentration (atoms / cm 3 ) is calculated from the depth distribution of Sn atoms. 120 Sn quartz glass is used as a standard sample. As the analysis conditions of SIMS, for example, the following conditions can be listed. It should be noted that the analysis conditions shown below are examples and should be appropriately changed according to the measuring device, sample, etc. In particular, when the plotting interval of the depth distribution of the Sn atomic concentration is 0.05 μm or more, it is necessary to change the following analysis conditions so that the plotting interval is less than 0.05 μm. It should be noted that the measurement accuracy of the Sn atomic concentration near the surface in SIMS may be reduced due to the influence of surface contamination, etc. Therefore, when calculating the Sn atomic concentration of the surface part of the glass substrate, the area with a depth of 0.1 μm to 0.3 μm from the main surface is regarded as the surface part of the glass substrate. In addition, when calculating the concentration gradient of Sn atoms in the surface part, 0.1 μm to 0.5 μm (0.1×10 -4 cm~0.5×10 -4 cm), the depth unit of the horizontal axis is set to cm.

[0041] The Sn atomic concentration in the surface layer of the glass substrate is obtained by averaging the Sn atomic concentration in the region from a depth of 0.1 μm to a depth of 0.3 μm from the main surface. Therefore, the Sn atomic concentration in the surface layer of the glass substrate can also be referred to as the average Sn atomic concentration in the surface layer of the glass substrate.

[0042] The Sn atomic concentration inside the glass substrate is obtained by averaging the Sn atomic concentration within a region from a depth of 9.0 μm to a depth of 9.2 μm from the main surface.

[0043] (Analysis Conditions)

[0044] Apparatus: Quadrupole secondary ion mass spectrometer (ADEPT1010) manufactured by ULVAC-PHI

[0045] Primary ion type: O X + (oxygen ions)

[0046] Acceleration voltage of primary ions: 6keV

[0047] Primary ion current value: 100nA

[0048] Grating size of primary ions: 80μm×80μm square

[0049] Secondary ion detection area: 4% of the primary ion raster size (If the primary ion raster size is 80 μm × 80 μm square, the secondary ion detection area is 16 μm × 16 μm square.)

[0050] Detection of secondary ion species: 30 Si + 、 120 Sn + 、 124 Sn +

[0051] Under the above conditions, the depth of the glass substrate and the standard sample in the plate thickness direction was sputtered to obtain 30 Si + 、 120 Sn + 、 124 Sn + The horizontal axis of the depth distribution is the sputtering time, and the vertical axis is the secondary ion intensity.

[0052] Here, when measuring the Sn atomic concentration in a glass substrate containing Sr, it is preferable to use 124 Sn + This is because, in a glass substrate containing Sr, for example, the natural isotope ratio is the largest 120 Sn and 88 Sr+ 16 O+ 16 O and other substances have mass interference, and the natural isotope ratio is second only to 120 Sn 118 Sn and 88 Sr+ 30 Si and other materials will cause mass interference. 124 Sn and 88 Sr+ 18 O+ 18 O mass interference occurs, but considering 18 The natural isotope content ratio of O, 88 Sr+ 18 O+ 18 The detection intensity of O is very small and can be ignored.

[0053] It should be noted that, in this manual, 124 Sn + The standard sample for the relative sensitivity coefficient is quartz glass, which does not contain Sr and therefore has no mass interference caused by Sr. Therefore, the relative sensitivity coefficient can be measured in the standard sample. 120Sn. The standard sample is ion implanted in quartz glass 120 Sn made.

[0054] Next, the depth of the analysis pits formed by sputtering was measured using a stylus-type profilometer such as the Dektak150 manufactured by Veeco. The sputtering rate was calculated from the depth of the analysis pits. The horizontal axis of the depth distribution for the glass substrate and the standard sample was converted from sputtering time to depth. The horizontal axis of the depth distribution increases in the positive direction from a depth of 0 μm to a depth of X μm in the thickness direction.

[0055] Next, consider 124 Sn and 120 The natural existence ratio of Sn is (5.94 / 32.85=0.181), and the standard sample 120 Sn + The depth distribution is transformed into 124 Sn + The depth distribution of 124 Sn + The relative sensitivity coefficient of 30 Si + .

[0056] Finally, the use of glass substrates 30 Si + and 124 Sn + The depth distribution and 124 Sn + The relative sensitivity coefficient of Sn atomic concentration (atom / cm 3 ) is the depth distribution on the vertical axis. Based on the depth distribution of the Sn atomic concentration of the glass substrate, the Sn atomic concentrations at the surface and inside the glass substrate are calculated, and further, the Sn atomic concentration gradient is calculated. It should be noted that when the Sn atomic concentration decreases from the surface of the glass substrate to the inside of the glass substrate (depth in the thickness direction), the Sn atomic concentration gradient becomes a negative value.

[0057] It should be noted that when the depth profile of Sn atomic concentration is plotted at an interval of 0.05 μm or greater, it is necessary to appropriately change the primary ion acceleration voltage, current value, and raster size within the above-mentioned analysis conditions to reduce the sputtering rate. For example, if the primary ion acceleration voltage is reduced, the sputtering rate will decrease.

[0058] It should be noted that, when a patterned resin film is formed on the surface of the glass substrate, it is actually difficult to perform SIMS analysis from the surface side of the glass substrate. By grinding the glass substrate from the opposite side of the resin film surface, the above-mentioned SIMS analysis is performed from the grinding surface side, and the depth distribution of the Sn atom concentration can be obtained. The thickness of the glass substrate after grinding is ideally about 10 μm. It should be noted that, when the concentration of Sn atoms decreases from the surface portion (resin film surface side) to the inside (opposite side of the resin film surface) (depth in the thickness direction) in the thickness direction, the value of the Sn atom concentration gradient becomes a negative value.

[0059] Examples of the resin film include resin films containing acrylic resin, epoxy resin, polyimide resin, polyester resin, and the like, and black matrix films made of resins in which a black substance such as fine carbon is dispersed and mixed.

[0060] In the glass substrate of one embodiment of the present invention, the Sn atomic concentration gradient in the surface layer of the glass substrate is preferably -1.0×10 23 atoms / cm 4 Above and -1.0×10 22 atoms / cm 4 The Sn atomic concentration gradient in the surface layer of the glass substrate refers to the concentration gradient of Sn atoms in the glass substrate surface layer when the depth of the glass substrate is 0.1 μm to 0.5 μm (0.1×10 -4 cm~0.5×10 -4 The Sn atomic concentration (atoms / cm) in the region 3 ) is the slope of a linear function obtained by linearly approximating the depth distribution of .

[0061] The Sn atomic concentration gradient in the surface layer of the glass substrate is more preferably -9.6×10 22 atoms / cm 4 Above, particularly preferably -9.0×10 22 atoms / cm 4 Above, the most preferred is -8.5×10 22 atoms / cm 4 If the Sn atomic concentration gradient in the surface layer of the glass substrate is -1.0×10 22 atoms / cm 4 Below, the divalent Sn atoms diffuse into the film formed on the surface of the glass substrate, thereby further improving the adhesion between the glass substrate and the film. In addition, if the Sn atom concentration gradient of the surface layer of the glass substrate is -1.0×10 23 As described above, it is expected that the problem of Sn atoms emitting fluorescent light can be reduced in the device manufacturing process using a glass substrate.

[0062] The glass substrate according to one embodiment of the present invention preferably includes alkali-free glass, and the alkali-free glass preferably contains, expressed in mol % based on oxides:

[0063] 50% to 75% SiO2,

[0064] 7% to 25% Al2O3, and

[0065] 0.1% to 12% B2O3, and

[0066] The total content of MgO, CaO, SrO, and BaO is 7% to 25%.

[0067] Alkali-free glass refers to glass that contains substantially no alkali metal oxides such as Na2O, K2O, and Li2O. Here, "substantially free of alkali metal oxides" means that the glass contains no alkali metal oxides, excluding unavoidable impurities introduced from the raw materials. In other words, the glass does not intentionally contain alkali metal oxides.

[0068] The SiO2 content is preferably 50% or more, more preferably 55% or more, further preferably 60% or more, particularly preferably 62% or more, and most preferably 64% or more. Furthermore, the SiO2 content is preferably 75% or less, more preferably 72% or less, further preferably 70% or less, and particularly preferably 68% or less. By setting the SiO2 content to 50% or more, a decrease in acid resistance, an increase in density, a decrease in strain point, an increase in the linear expansion coefficient, and a decrease in Young's modulus can be prevented. By setting the SiO2 content to 75% or less, an increase in high-temperature viscosity and a decrease in solubility can be prevented.

[0069] The Al2O3 content is preferably 7% or more, more preferably 9% or more, even more preferably 10% or more, and particularly preferably 11% or more. Furthermore, the Al2O3 content is preferably 25% or less, more preferably 20% or less, even more preferably 17% or less, particularly preferably 15% or less, and most preferably 13% or less. By setting the Al2O3 content to 7% or more, a significant increase in the devitrification temperature, which could easily cause devitrification in the glass, can be prevented. Furthermore, by setting the Al2O3 content to 25% or less, an increase in viscosity, a rise in the melting temperature, and the incorporation of bubbles can be prevented.

[0070] The B2O3 content is preferably 0.1% or greater, more preferably 1% or greater, and even more preferably 3% or greater. Furthermore, the B2O3 content is preferably 12% or less, more preferably 10% or less, and even more preferably 9% or less. A B2O3 content of 0.1% or greater improves the melting reactivity of the glass and lowers the devitrification temperature. Furthermore, a B2O3 content of 12% or less improves acid resistance.

[0071] The total content of MgO, CaO, SrO, and BaO (MgO + CaO + SrO + BaO) is preferably 7% or more, more preferably 10% or more, even more preferably 11% or more, particularly preferably 12% or more, and most preferably 15% or more. Furthermore, the total content is preferably 25% or less, more preferably 22% or less, even more preferably 21% or less, particularly preferably 20% or less, and most preferably 19.5% or less. By setting the MgO + CaO + SrO + BaO content to 7% or more, the meltability of the glass is improved. Furthermore, by setting the MgO + CaO + SrO + BaO content to 25% or less, the density and thermal expansion coefficient of the glass are reduced.

[0072] MgO is a component that reduces the density and thermal expansion coefficient of alkali-free glass, prevents excessively lowering the strain point, and improves its solubility. When MgO is contained, to achieve these effects, the MgO content is preferably 1.5% or more, more preferably 3% or more, even more preferably 4% or more, particularly preferably 5% or more, and most preferably 7% or more. Furthermore, to suppress phase separation in alkali-free glass and improve devitrification, acid resistance, and BHF (buffered hydrofluoric acid) resistance, the MgO content is preferably 15% or less, more preferably 12% or less, and even more preferably 10% or less.

[0073] CaO is a component that reduces the density and thermal expansion coefficient of alkali-free glass, prevents excessively lowering the strain point, and improves its solubility. When CaO is contained, to achieve these effects, the CaO content is preferably 3% or more, more preferably 5% or more, and even more preferably 7% or more. Furthermore, from the perspective of improving the devitrification characteristics, acid and alkali resistance, and reducing the density and thermal expansion coefficient of the alkali-free glass, the CaO content is preferably 15% or less, more preferably 12% or less, and even more preferably 10% or less.

[0074] SrO is a component that reduces the density and thermal expansion coefficient of alkali-free glass, prevents excessively lowering the strain point, and improves its meltability. When SrO is present, to achieve these effects, the SrO content is preferably 0.5% or more, more preferably 1% or more, and even more preferably 3% or more. Furthermore, to improve the devitrification characteristics, acid and alkali resistance, and reduce the density and thermal expansion coefficient of the alkali-free glass, the SrO content is preferably 10% or less, more preferably 8% or less, and even more preferably 6% or less.

[0075] BaO is not an essential component, but may be contained to suppress phase separation in alkali-free glass and improve devitrification and chemical resistance. However, a large amount of BaO tends to increase specific gravity, decrease Young's modulus, and excessively increase the average thermal expansion coefficient. Therefore, the BaO content is preferably 5% or less, more preferably 1% or less, and even more preferably 0.5% or less. It is particularly preferred that the alkali-free glass of the present invention contain substantially no BaO.

[0076] It should be noted that, in this specification, "substantially free of" means that it contains no impurities other than unavoidable impurities mixed from raw materials, etc., that is, it is not intentionally contained. In the present invention, substantially free of BaO means, for example, that the BaO content is 0.3% or less, preferably 0.2% or less.

[0077] As a composition of the alkali-free glass used for the glass substrate which is one embodiment of the present invention, the following compositions can be mentioned, for example.

[0078] (1) Glass containing 64% to 67% SiO2, 10% to 12% Al2O3, 7% to 9% B2O3, 5% to 7% MgO, 4% to 6% CaO, 4% to 6% SrO, and 0% to 1% BaO, with MgO + CaO + SrO + BaO being 15% to 17%

[0079] (2) Glass containing 65% to 69% SiO2, 11% to 14% Al2O3, 0.5% to 2% B2O3, 8% to 10% MgO, 4% to 6% CaO, 3% to 5% SrO, and 0% to 1% BaO, with MgO + CaO + SrO + BaO being 18% to 20%

[0080] (3) Glass containing 63% to 69% SiO2, 10% to 16% Al2O3, 0.5% to 3.5% B2O3, 7% to 13% MgO, 5% to 10% CaO, 0.5% to 4% SrO, 0% to 3% BaO, and MgO + CaO + SrO + BaO is 17% to 22%

[0081] (4) Glass containing 65% to 69% SiO2, 9% to 13% Al2O3, 8% to 12% B2O3, 0% to 4% MgO, 7% to 11% CaO, 0% to 3% SrO, 0% to 1% BaO, and 0% to 1% SnO2, with MgO+CaO+SrO+BaO being 10% to 14%

[0082] In the glass substrate according to one embodiment of the present invention, the content of alkali metal oxides in the alkali-free glass is preferably 0.5% or less, more preferably 0.2% or less, even more preferably 0.1% or less, particularly preferably 0.08% or less, and most preferably 0.05% or less. By setting the content of alkali metal oxides to 0.5% or less, it is possible to suppress the diffusion of alkali metal ions into a film, such as a resin film, formed on the glass substrate, thereby reducing the deterioration of film properties. Examples of alkali metal oxides include Na2O, K2O, and Li2O.

[0083] In the glass substrate of one embodiment of the present invention, the strain point of the alkali-free glass is preferably 650° C. or higher, and the average thermal expansion coefficient at 50° C. to 350° C. is preferably 30×10 -7 / ℃~45×10 -7 / ℃.

[0084] The strain point of the alkali-free glass is preferably 650°C or higher, more preferably 670°C or higher, and even more preferably 700°C or higher. Setting the strain point of the alkali-free glass to 650°C or higher can suppress thermal deformation and dimensional changes during flat panel display manufacturing. The upper limit of the strain point is not limited, but is typically 750°C or lower. The strain point is measured by the fiber elongation method in accordance with JIS R3103-2 (2001).

[0085] The average thermal expansion coefficient of the alkali-free glass at 50°C to 350°C is preferably 30×10 -7 / ℃ or more, more preferably 32×10 -7 / ℃ or more, more preferably 35×10 -7 / ℃ or more. In addition, the average thermal expansion coefficient is preferably 45×10 -7 / ℃ or less, more preferably 43×10 -7 / ℃ or less, more preferably 40×10 -7 / ℃ or less. By making the above average thermal expansion coefficient 30×10 -7 / ° C or more, it is possible to prevent the difference in the average thermal expansion coefficient between the alkali-free glass and the film such as the resin film formed on the glass substrate from becoming too large. In addition, by making the average thermal expansion coefficient 45×10 -7 / °C or less, it is possible to suppress the thermal shock resistance from becoming excessively low.

[0086] The average coefficient of thermal expansion at 50°C to 350°C was measured as follows. The glass was held at the slow cooling point for 30 minutes and then slowly cooled at a rate of 60°C / minute. The slowly cooled glass was then measured using a differential thermal dilatometer (TMA) to measure the linear expansion versus temperature curve from room temperature to 400°C. The average coefficient of thermal expansion at 50°C to 350°C was calculated as the average coefficient of thermal expansion.

[0087] The glass substrate of one embodiment of the present invention is preferably a float glass produced by a float process. The float process allows for easy upsizing of the glass substrate and provides excellent flatness and homogeneity.

[0088] In one embodiment of the glass substrate of the present invention, at least one main surface is preferably a ground surface formed by grinding. By making the main surface a ground surface, foreign matter (e.g., foreign matter defects caused by tin adhesion) and scratches adhering to the surface of the glass substrate can be removed, and defects (e.g., pattern defects, protrusions, pinholes, broken lines, etc.) when patterning a film such as a resin film formed on the surface of the glass substrate can be suppressed, thereby enabling the formation of finer patterns.

[0089] In the glass substrate of one embodiment of the present invention, the texture direction index (Stdi value) of the polished surface is preferably 0.75 or less. The Stdi value is a parameter calculated by performing a roughness analysis on a shape image obtained by atomic force microscopy (AFM) with a 1 μm × 1 μm square observation field and 256 × 256 pixels, and then performing a homogenization process using image analysis software (e.g., SPIP, manufactured by Image Metrology).

[0090] Based on the shape image obtained by AFM in a 1 μm × 1 μm square observation field and at a pixel count of 256 × 256, the Stdi value calculated by image analysis software is preferably 0.75 or less, more preferably 0.74 or less, particularly preferably 0.72 or less, and most preferably 0.70 or less. The lower limit of the Stdi value is not particularly limited, but is typically 0.20 or more. By having an Stdi of 0.75 or less, the glass substrate is sufficiently free of foreign matter attached to the surface by polishing.

[0091] The Stdi value is an indicator of the quality of the directionality of the texture formed on the glass surface (a property or state consistently present on a processed surface), and takes a value between 0 and 1. If the texture has a predominant directionality, the Stdi value is close to 0. On the other hand, if the texture has no directionality, the Stdi value is close to 1. In other words, if a directional texture is formed on the glass surface by polishing, the Stdi value is close to 0. The Stdi value can be determined by obtaining a shape image using AFM and then using image analysis software (e.g., SPIP, manufactured by Image Metrology).

[0092] The thickness of the glass substrate of one embodiment of the present invention is not particularly limited. When the thickness is 0.7 mm or less, lightweighting can be achieved, which is therefore preferred. The thickness of the alkali-free glass of the present invention is more preferably 0.65 mm or less, further preferably 0.55 mm or less, particularly preferably 0.45 mm or less, and most preferably 0.4 mm or less. The thickness can also be 0.1 mm or less or 0.05 mm or less. However, from the perspective of preventing deflection due to its own weight, the thickness is preferably 0.1 mm or more, more preferably 0.2 mm or more.

[0093] In the glass substrate of one embodiment of the present invention, the difference in fluorescence intensity (ΔI 400 ) is preferably less than 90. ΔI 400 The fluorescence intensity (Ib) at a wavelength of 400 nm on the main surface of the glass substrate after removing 8 μm of the main surface of the glass substrate in the thickness direction is shown. 400 ) and the fluorescence intensity (Is 400 ) difference (Is 400 -Ib 400 ).

[0094] The difference in fluorescence intensity at a wavelength of 400 nm before and after the removal of the surface layer (ΔI 400 ) is 90 or less, it is expected that the adverse effects caused by the fluorescence of Sn atoms can be reduced in the device manufacturing process using a glass substrate. The fluorescence intensity difference (ΔI 400 ) is more preferably 85 or less, further preferably 80 or less, particularly preferably 75 or less, and most preferably 70 or less.

[0095] The fluorescence intensity difference (ΔI 400 ) is too small, which means that the amount of Sn atoms diffused into the surface of the glass substrate is small, and the adhesion between the glass substrate and the film formed on the surface of the glass substrate may be deteriorated. Therefore, the fluorescence intensity difference (ΔI 400 ) is preferably 5 or more, more preferably 10 or more, further preferably 20 or more, particularly preferably 25 or more, and most preferably 30 or more.

[0096] Fluorescence intensity is measured using a fluorescence spectrophotometer (e.g., manufactured by Hitachi High-Tech Scientific Corporation, model: F-7000) in the range of 300nm to 600nm. In the measurement conditions of fluorescence intensity, the excitation light wavelength is set to 240nm, the tube voltage is set to 350V, the excitation side slit width is set to 10nm, the fluorescence side slit width is set to 10nm, and a filter with a wavelength of light cutoff of 295nm or less is used on the fluorescence side. It should be noted that, in order to stabilize the light source intensity and the sensitivity of the detector, the measurement of fluorescence intensity is carried out after more than 1 hour after starting the fluorescence spectrophotometer. Under the above-mentioned measurement conditions, fluorescence intensity is an arbitrary unit.

[0097] <Method for manufacturing a glass substrate>

[0098] The glass substrate of one embodiment of the present invention can be produced, for example, by the following method. Glass raw materials containing a clarifier such as SnO2 are melted as needed, and then the molten glass is formed into a sheet-shaped glass ribbon by a float process, a fusion process, or the like. The glass ribbon is then cut into pieces of a predetermined size. Furthermore, the formed sheet-shaped glass is polished and cleaned as needed.

[0099] In the method for manufacturing a glass substrate according to one embodiment of the present invention, the glass substrate is formed using a float process. During the float process, molten tin and glass components diffuse into each other, causing divalent Sn atoms to be present on the glass surface. This improves the adhesion between a film such as a resin film formed on the surface of the glass substrate and the glass substrate. Therefore, the method for manufacturing a glass substrate according to one embodiment of the present invention preferably includes a forming step using a float process.

[0100] The method for producing a glass substrate according to one embodiment of the present invention includes a forming step using a float process, a polishing step, and a cleaning step of cleaning the polished glass substrate, which will be described below.

[0101] As described above, in one embodiment of the present invention, the glass substrate preferably has foreign matter attached to the surface of the glass substrate sufficiently removed by grinding. On the other hand, from the perspective of improving the productivity of the glass substrate, the grinding amount in the grinding step is preferably small. Therefore, when the glass substrate before grinding is a glass with a small amount of foreign matter attached to the surface, the grinding amount in the grinding step can be reduced, which is preferable.

[0102] Glass with minimal foreign matter adhering to its surface can be produced by appropriately adjusting the conditions of the float process. Specifically, for example, the temperature of the molten glass at the inlet of the float furnace is preferably set to 1400°C or lower, more preferably to a maximum of 1100°C to 1400°C (within the range of 1400°C to 1100°C), further preferably to 1350°C or lower, even more preferably to a maximum of 1150°C to 1350°C (within the range of 1150°C to 1350°C), particularly preferably to 1320°C or lower, and most preferably to a maximum of 1180°C to 1320°C (within the range of 1180°C to 1320°C). By setting the temperature of the molten glass at the inlet of the float furnace to 1400°C or lower, foreign matter such as defects caused by molten tin is less likely to adhere to the glass surface. This allows for the production of a glass substrate in which foreign matter adhering to the surface has been sufficiently removed with minimal polishing.

[0103] In the grinding process, for example, a grinding pad is used and an abrasive (slurry) containing abrasive grains is used to grind the surface of the glass substrate. The abrasive grains contained in the grinding grain are not particularly limited, and particles such as silica particles, aluminum oxide particles, cerium oxide particles, titanium dioxide particles, zirconium oxide particles, and manganese oxide particles can be cited. From the perspective of grinding efficiency, cerium oxide particles are particularly preferred. The average particle size of the abrasive grains is preferably in the range of 0.8 μm to 1.5 μm, for example. By undergoing such a grinding process, the Stdi value measured on the surface of the glass substrate using AFM can reach 0.75 or less, which is therefore preferred.

[0104] From the perspective of making the surface-diffused Sn concentration in the surface of the glass substrate a specified concentration, the grinding amount in the grinding process is preferably less than 2.0 μm, more preferably less than 1.8 μm, further preferably less than 1.5 μm, further preferably less than 1.0 μm, particularly preferably less than 0.7 μm, and most preferably less than 0.5 μm.

[0105] In the cleaning process, the surface of the glass substrate is cleaned with an acidic cleaning solution and then, if necessary, with an alkaline cleaning solution. When the glass substrate is a glass substrate made of aluminoborosilicate glass, such as used in liquid crystal displays (LCDs), cleaning the glass substrate with an acidic cleaning solution can cause glass components such as aluminum ions to leak out from the surface of the glass substrate, forming a highly hydrophilic layer containing an excessive amount of OH groups. This layer can sometimes reduce the adhesion between a film such as a resin film and the glass substrate.

[0106] In the glass substrate of one embodiment of the present invention, the surface layer of the glass substrate is diffused with Sn atoms at a concentration of 2.0×10 18 atoms / cm 3As a result, the adhesion between the glass substrate and a film such as a resin formed on the glass substrate can be improved. Therefore, even when the glass substrate is cleaned with an acidic cleaning solution, causing glass components such as aluminum ions to leak out from the surface of the glass substrate, a glass substrate with excellent adhesion to the film such as a resin can be provided. According to one embodiment of the present invention, the glass substrate can be appropriately cleaned using acidic or alkaline cleaning solutions, which can significantly reduce foreign matter adhering to the surface, thereby providing a glass substrate with excellent cleanability.

[0107] The glass substrate according to one embodiment of the present invention is a glass substrate comprising aluminum-containing silicate glass, and the ΔAl / Si value is preferably greater than 0.26. The ΔAl / Si value is the value obtained by subtracting the Al / Si value of the surface of the glass substrate, as measured by X-ray photoelectron spectroscopy, from the Al / Si value obtained by dividing the Al atomic concentration (atomic %) within the glass substrate by the Si atomic concentration (atomic %).

[0108] When the ΔAl / Si value is greater than 0.26, a glass substrate having excellent cleanability can be provided by appropriately cleaning the surface of the glass substrate with an acidic or alkaline cleaning solution, thereby sufficiently reducing adhered foreign matter. ΔAl / Si is more preferably 0.27 or greater.

[0109] In the method for manufacturing a glass substrate according to one embodiment of the present invention, by preferably including a forming step using a float process, the surface-diffused Sn concentration of the glass substrate is adjusted to a predetermined concentration, thereby improving the adhesion between a film such as a resin film and the glass substrate.

[0110] The cleaning method is not particularly limited as long as it is a method of directly contacting the cleaning liquid with the surface of the glass substrate to clean it. Examples of cleaning methods include scrubbing cleaning, spray cleaning (spray cleaning), and dip cleaning. The temperature of the cleaning liquid is not particularly limited and can be used at room temperature (15°C) to 95°C. If the temperature is higher than 95°C, the water in the cleaning liquid may boil, which is inconvenient for the cleaning operation.

[0111] Examples of organic acids included in the acidic cleaning solution include, but are not limited to, organic carboxylic acids such as ascorbic acid and citric acid, and organic phosphonic acids. These organic acids may be added to the cleaning solution together with an inorganic acid (e.g., sulfuric acid, phosphoric acid, nitric acid, hydrofluoric acid, hydrochloric acid, etc.), or the inorganic acid may be used alone. Furthermore, when using the above-mentioned inorganic acids, salts of these acids may be added together with the inorganic acid to suppress pH fluctuations.

[0112] From the perspective of cleaning properties, the cleaning liquid may contain compounds such as organic carboxylic acids and organic phosphonic acids having a chelating effect. However, since these compounds may promote the release of components such as aluminum from the glass, it is preferred that the cleaning liquid not contain these compounds.

[0113] Here, examples of the organic carboxylic acid having a chelating effect include dicarboxylic acid chelating agents, tricarboxylic acid chelating agents, gluconic acid chelating agents, nitrilotriacetic acid chelating agents, and iminosuccinic acid chelating agents.

[0114] Organic phosphonic acid refers to an organic compound having a structure represented by the formula: -P(=O)(OH)2 in which a phosphonic acid group is bonded to a carbon atom. The number of phosphonic acid groups represented by the above formula per molecule of the organic phosphonic acid is preferably 2 or more, more preferably 2 to 8, and particularly preferably 2 to 4.

[0115] Preferred organic phosphonic acids include compounds having a structure in which a hydrogen atom bonded to a carbon atom of a hydrocarbon that may have a substituent is replaced by a phosphonic acid group; and compounds having a structure in which a hydrogen atom bonded to a nitrogen atom of ammonia or an amine is replaced by a methylenephosphonic acid group represented by -CH2-P(=O)(OH)2. Specific examples include methylenediphosphonic acid (methylenediphosphonic acid).

[0116] The alkaline cleaning solution contains an alkali, and in addition to the alkali, it may also contain a chelating agent and a surfactant. From the perspective of cleaning performance, a chelating agent may also be included in the cleaning solution. It should be noted that a chelating agent may promote the removal of aluminum components from the glass.

[0117] Examples of the base contained in the alkaline cleaning solution include alkali metal compounds such as alkali metal hydroxides and alkali metal carbonates, amines, and quaternary ammonium hydroxides. As the base, alkali metal hydroxides such as potassium hydroxide and sodium hydroxide are preferred.

[0118] Examples of the chelating agent include ethylenediaminetetraacetic acid-based chelating agents, gluconic acid-based chelating agents, nitrilotriacetic acid-based chelating agents, and iminosuccinic acid-based chelating agents. Ethylenediaminetetraacetic acid-based chelating agents are particularly preferred. As the surfactant, a nonionic surfactant is preferred.

[0119] The washing step may be followed by drying. Examples of drying methods include hot air blowing and compressed air blowing.

[0120] When a resin film or other film is formed on the surface of the glass substrate thus obtained, products such as color liquid crystal display panels can be manufactured with high adhesion to the film and good yield. For example, when manufacturing a color liquid crystal display panel, a black matrix film, a color filter layer, an overcoat layer, and an ITO transparent conductive film can be sequentially formed on at least one of the main surfaces of the glass substrate.

[0121] Here, the black matrix is ​​preferably formed using a resin such as an acrylic resin, epoxy resin, polyimide resin, or polyester resin, which can be patterned with good dimensional accuracy and in which a black substance such as fine carbon is dispersed and mixed. A black matrix film is formed by conventional patterning. Alternatively, the color filter layer can be formed using conventional materials used in color liquid crystal displays using conventional methods such as pigment dispersion, film transfer, dyeing, printing, and electrodeposition.

[0122] In addition, in order to flatten the unevenness generated at the boundaries of the R, G, and B color filter layers provided on the black matrix film, an overcoat layer may be provided, which may be formed using a known method using acrylic resin, epoxy resin, polyimide resin, etc. Furthermore, an ITO transparent electrode film may be formed using a known method.

[0123] Since the liquid crystal display panel thus obtained uses the glass substrate of the present invention, films such as the black matrix film are not easily peeled off from the glass substrate during manufacturing and use, resulting in a good product yield and stable performance.

[0124] [Example]

[0125] Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited to these Examples. In addition, regarding the measurement results of physical properties in the tables, blank columns indicate that the results were not measured.

[0126] [Evaluation method]

[0127] [Residual resolution]

[0128] The adhesion between the black matrix film as a resin film and the glass substrate was evaluated according to the following procedure: The evaluation was performed using a photosensitive black matrix-forming resin composition containing a binder resin, a crosslinking agent, a photopolymerization initiator, a silane coupling agent, and carbon black.

[0129] Next, the photosensitive black matrix-forming resin composition was applied (spin-coated) on the surface of the cleaned glass substrate using a spin coater, and then heated and dried at 85° C. for 90 seconds using a hot plate to form a coating film.

[0130] Then, exposure was performed through a photomask using an exposure device (illuminance: 30 mW / cm 2 , Exposure: 30mJ / cm2 The glass substrate was then developed using a 0.08% KOH aqueous solution for 70 seconds using a developer. This evaluation was conducted under strict development conditions, including a high KOH concentration and a long development time. Subsequently, the glass substrate was rinsed with pure water to form a resin black matrix film pattern.

[0131] The photomask has four types of pattern shapes, L1 to L4, shown below, and a total of 105 types of patterns were obtained by changing the line width of each type by 1 μm.

[0132] L1: Pattern spacing is 100 μm, and there are 25 linear patterns in one block (2835 μm × 2000 μm) (line width is variable within the range of 1 μm to 25 μm)

[0133] L2: Pattern spacing is 50 μm, and there are 30 linear patterns in one block (2952.6 μm × 2000 μm) (line width is variable within the range of 1 μm to 30 μm)

[0134] L3: Pattern spacing is 200 μm, and there are 25 linear patterns in one block (2682.5 μm × 2000 μm) (line width is variable within the range of 1 μm to 25 μm)

[0135] L4: Pattern spacing is 200 μm, and there are 25 short line patterns in one block (2682.5 μm × 2000 μm) (line width is variable within the range of 1 μm to 25 μm)

[0136] A laser microscope (Keyence VK-9510) was used to observe the glass substrate after cleaning with pure water. The line width of the mask pattern (hereinafter referred to as residual resolution) of the resin black matrix film remaining on the glass substrate was measured for each of the four pattern shapes L1 to L4. The average residual resolution of each of the four pattern shapes was then calculated. It should be noted that the smaller the residual resolution value, the higher the adhesion of the resin black matrix film formed on the cleaned glass substrate.

[0137] [Surface cleanliness]

[0138] The surface of the glass substrate evaluated for the residual resolution was observed with a laser microscope to evaluate surface foreign matter and pattern defects (chips, convex defects, pinholes). The evaluation was as follows.

[0139] A: There are less than 5 foreign matter and pattern defects on the surface

[0140] B: There are more than 6 foreign objects or pattern defects on the surface

[0141] Pattern defects are related to the cleanliness of the glass substrate surface and occur when the glass substrate surface is not cleaned sufficiently or when there is a lot of foreign matter attached to the glass substrate surface.

[0142] [SIMS measurement]

[0143] The Sn atomic concentration (atom / cm 3 ) depth distribution, and calculate the surface diffusion Sn atomic concentration (atoms / cm 3 The surface diffusion Sn atomic concentration was determined by measuring the Sn atomic concentration in the surface layer [Sn atomic concentration in the region from 0.1 μm to 0.3 μm in depth (atoms / cm 3 )], the internal Sn atomic concentration [Sn atomic concentration in the region from 9.0 μm to 9.2 μm (atoms / cm 3 )], the Sn atomic concentration in the interior is subtracted from the Sn atomic concentration in the surface layer.

[0144] In addition, the concentration gradient of Sn atoms in the surface layer is calculated from the depth of 0.1 μm to the depth of 0.5 μm (0.1×10 -4 cm~0.5×10 -4 The Sn atomic concentration (atoms / cm) in the area 3 ) is linearly approximated to obtain the slope of the linear function. It should be noted that the depth distribution of Sn atomic concentration is plotted at an interval of approximately 0.04 μm. In addition, when the concentration of Sn atoms decreases from the surface to the inside (depth in the thickness direction) in the thickness direction, the value of the Sn atomic concentration gradient is negative. The unit of the Sn atomic concentration gradient is atoms / cm 4 .

[0145] [Relative concentration of Sn]

[0146] The X-ray Photoelectron Spectroscopy (XPS) was used to determine the 3d5 / 2 Track and Si 2p The photoelectron spectrum corresponding to the orbital. Remove the background from the above photoelectron spectrum and find the 3d5 / 2 Track and Si 2p The area of ​​the photoelectron peak corresponding to the orbital is taken as the area from Sn 3d5 / 2 The number of photoelectrons per unit time N Sn 、From Si 2p The number of photoelectrons per unit time N Si The background is removed by comparing the Sn 3d5 / 2 Track and Si 2pThe orbital-corresponding photoelectron peaks were analyzed using the same function.

[0147] The relative concentration of Sn C0 was calculated by using N Sn and N Si And calculate according to the following formula.

[0148] C0=(N Sn / 486.028) / [(N Si / 34.52)+(N Sn / 486.028)]=N Sn / (14.08N Si +N Sn )

[0149] Here, 486.028 and 34.52 are the relative sensitivity coefficients with respect to Sn and Si, respectively.

[0150] The XPS measurement conditions are as follows.

[0151] Measuring device: Quantera-SXM manufactured by ULVAC-PHI

[0152] Monitoring peak: N si [Si 2p ]、N Sn [Sn 3d5 / 2 ]

[0153] Detection angle (the angle between the sample surface and the detector): 45°

[0154] Analysis software [MultiPak (trademark) manufactured by ULVAC-PHI Co., Ltd.] was used for XPS spectrum analysis. The Shirley method was applied to the background subtraction method of the spectrum.

[0155] [ΔAl / Si value]

[0156] The Al atomic concentration and Si atomic concentration inside and on the surface of the glass substrate are measured by X-ray photoelectron spectroscopy (XPS). The ratio of the Al atomic concentration to the Si atomic concentration inside the glass substrate is referred to as the internal Al / Si value (atomic concentration ratio). In addition, the ratio of the Al atomic concentration to the Si atomic concentration on the surface of the glass substrate is referred to as the surface Al / Si value (atomic concentration ratio). The value obtained by subtracting the surface Al / Si value from the internal Al / Si value is referred to as the ΔAl / Si value (atomic concentration ratio). The following describes the procedures for measuring the surface Al / Si value and the internal Al / Si value.

[0157] <Measurement of Surface Al / Si Value>

[0158] XPS was used to measure the Al atomic concentration and Si atomic concentration in the main surface of the glass substrate to determine the Al / Si value (atomic concentration ratio). The measurement was performed using a PHI5500 manufactured by ULVAC-PHI, using the Si (2p) and Al (2p) peaks, with a pass energy of 117.4 eV, an energy step size of 0.5 eV / step, and a detection angle (the angle between the sample surface and the detector) of 15°. The energy spectrum was analyzed using the analysis software MultiPak. The Shirley method was used to subtract the background from the energy spectrum.

[0159] <Measurement of internal Al / Si value>

[0160] Utilize the above method to measure the surface Al / Si value, then measure the depth direction distribution of Al atomic concentration and Si atomic concentration by the XPS using C60 ion sputtering. XPS measuring device and analytical software use the same device and software as the mensuration of surface Al / Si value. In addition, the subtraction method of the background of energy spectrum is applied Shirley method. In the measurement conditions, the direct energy is set to 117.4eV, the energy step is set to 0.5eV / step, the monitoring peak is set to Si (2p) and Al (2p), and the detection angle is set to 75 °. Then, the sputtering interval is set to 5 minutes, and when each sputtering is carried out for 5 minutes, the Al atomic concentration and the Si atomic concentration at the bottom of the formed pit are measured. Implement such measurement until Al atomic concentration and Si atomic concentration become constant region in the depth direction. Use the ratio of Al concentration and Si concentration in this constant concentration region as internal Al / Si value (atomic concentration ratio).

[0161] [Texture Direction Index (Stdi value)]

[0162] The shape image was obtained using an AFM manufactured by Bruker Corporation of Japan (model: Multimode VIIISPM, Nanoscope Vcontroller) under the following conditions.

[0163] Measurement mode: Tapping

[0164] Scan rate: 1Hz

[0165] Cantilever: AC160TS manufactured by Olympus

[0166] Observation field: 1μm×1μm

[0167] Resolution: 256×256 pixels

[0168] Then, the shape image was subjected to a leveling process using image analysis software (SPIP image analysis software, version 6.2.6, manufactured by Image Metrology), and the texture direction index (Stdi value) was determined by roughness analysis.

[0169] <Fluorescence spectrum measurement>

[0170] A fluorescence spectrophotometer (manufactured by Hitachi High-Tech Science Co., Ltd., model: F-7000) was used to measure the fluorescence intensity in the range of 300nm to 600nm. In the measurement conditions of the fluorescence intensity, the excitation light wavelength was set to 240nm, the tube voltage was set to 350V, the excitation side slit width was set to 10nm, the fluorescence side slit width was set to 10nm, and a filter that cut off light with a wavelength of 295nm or less was used on the fluorescence side. It should be noted that in order to stabilize the light source intensity and the sensitivity of the detector, the fluorescence intensity was measured after more than 1 hour had passed since the fluorescence spectrophotometer was started. Under the above-mentioned measurement conditions, the fluorescence intensity is an arbitrary unit. It should be noted that the fluorescence intensity of each sample was obtained by regression from the measured values ​​at several points, and the accuracy of the grinding process in each sample was within the range of 8.0μm±0.4μm.

[0171] The fluorescence intensity (Ib) at a wavelength of 400 nm on the main surface of the glass substrate after removing 8 μm of the main surface of the glass substrate in the thickness direction was measured. 400 ), and the fluorescence emission intensity (Is ) at a wavelength of 400 nm in the main surface of the glass substrate before the main surface is removed. 400 ). In addition, the difference in fluorescence intensity at a wavelength of 400 nm between before and after the main surface of the glass substrate is removed in the thickness direction, that is, before and after the surface layer is removed (Is 400 -Ib 400 ), which is used as the fluorescence intensity difference at a wavelength of 400 nm (ΔI 400 ΔI when “Grinding thickness (μm)” is “8” 400 Specifically, for example, it is “the difference between the fluorescence intensity of the glass substrate having a thickness of 8 μm (after removal) and the fluorescence intensity of the glass substrate having a thickness of 16 μm (before removal)”.

[0172] Table 1 shows the target compositions of the examples in terms of mol % based on oxides, and Table 2 shows the results of the examples. In Table 2, Example 1 is a reference example, Examples 2 to 5, 8, 10, and 11 are examples, and Examples 6, 7, and 9 are comparative examples.

[0173] [Manufacturing of glass substrates]

[0174] The raw materials of each component were blended to achieve the target composition shown in Table 1, melted in a continuous melting furnace, and formed into a sheet by a float process to obtain an alkali-free glass substrate. The surface of the glass substrate was polished to the polishing thickness shown in Table 2 using a polishing pad and an abrasive containing cerium oxide particles with an average particle size of 0.8 μm to 1.0 μm (manufactured by Showa Denko K.K., trade name: SHOROX A10).

[0175] An unpolished glass substrate (Example 1) and polished glass substrates (Examples 2 to 11) were scrubbed with a PVA rotating brush while spraying an acidic cleaning solution at a flow rate of 25 L per minute. During the cleaning step, the acidic cleaning solution was diluted with water to a pH of 2.7. The temperature of the cleaning solution was set at 25°C, and the scrubbing time was set at 3 to 5 seconds.

[0176] The glass substrates obtained in Examples 1 to 11 were used to evaluate various parameters by the above-mentioned methods, and the results are shown in Table 2. In addition, the relationship between the residual resolution and the internal Sn atomic concentration and the surface-diffused Sn atomic concentration is shown in Table 2. Figure 1 (a) and Figure 1 (b) in.

[0177] Table 1

[0178] Glass A B C D <![CDATA[SiO2]]> 65.8 65.8 66.9 65.2 <![CDATA[Al2O3]]> 10.8 10.8 13 13.5 <![CDATA[B2O3]]> 7.7 7.7 1.3 1.2 MgO 5.7 5.7 9 9.2 CaO 4.8 4.8 5.3 9.7 SrO 5 5 4.5 1.2 BaO 0 0 0 0 <![CDATA[SnO2]]> 0 0.1 0 0 MgO+CaO+SrO+BaO 15.5 15.5 18.8 20.1

[0179]

[0180] As shown in Table 2 and Figure 1 As shown in (b), it can be seen that the surface diffusion Sn atomic concentration is related to the adhesion between the glass substrate and the resin film. The surface diffusion Sn atomic concentration is 2.0×10 18 atoms / cm 3 As described above, it is possible to achieve excellent adhesion between the glass substrate and the film formed on the glass substrate. Figure 1 As shown in (a), it can be seen that the Sn atomic concentration inside the glass substrate does not contribute to improving the adhesion between the glass substrate and the film. In addition, as shown in Table 2, by making the surface layer diffuse Sn atomic concentration 1.4×10 19 atoms / cm 3 Then, the fluorescence emission caused by Sn atoms can be suppressed.

[0181] From these results, it can be seen that by diffusing Sn atoms in the surface layer of at least one main surface of the glass substrate to a concentration of 2.0×10 18 atoms / cm 3 Above and 1.4×10 19 atoms / cm 3As a result, it is possible to achieve excellent adhesion between the glass substrate and the film formed on the glass substrate and improve production efficiency.

[0182] The present invention has been described in detail and with reference to specific embodiments, but various changes and modifications can be made without departing from the spirit and scope of the present invention, which will be apparent to those skilled in the art. This application is based on Japanese patent application (Japanese Patent Application No. 2018-173839) filed on September 18, 2018, the contents of which are incorporated herein by reference.

Claims

1. A glass substrate comprising a pair of main surfaces and an end surface, wherein: When the Sn atomic concentration in the region of 0.1 μm to 0.3 μm from the main surface is defined as the Sn atomic concentration in the surface layer of the glass substrate, and the Sn atomic concentration in the region of 9.0 μm to 9.2 μm from the main surface is defined as the Sn atomic concentration in the interior of the glass substrate, In at least one main surface, the surface-diffused Sn atomic concentration obtained by subtracting the Sn atomic concentration inside the glass substrate from the Sn atomic concentration in the surface portion of the glass substrate is 2.0×10 18 atoms / cm 3 Above and 1.4×10 19 atoms / cm 3 the following, In the at least one main surface, When the slope of a linear function obtained by linearly approximating the depth distribution of the Sn atomic concentration in the region from a depth of 0.1 μm to a depth of 0.5 μm from the main surface is defined as the Sn atomic concentration gradient of the surface layer of the glass substrate, the Sn atomic concentration gradient of the surface layer of the glass substrate is -1.0×10 23 atoms / cm 4 Above and -1.0×10 22 atoms / cm 4 Hereinafter, the unit of Sn atomic concentration is atoms / cm 3 , The glass substrate comprises alkali-free glass, and the alkali-free glass comprises, expressed in mole % based on oxides: 63% to 69% SiO2, 10% to 16% Al2O3, 0.5% to 3.5% B2O3, 7% to 13% MgO, 5% to 10% CaO, 0.5% to 4% SrO, 0% to 3% BaO, The total content of MgO, CaO, SrO, and BaO is 17% to 22%.

2. The glass substrate according to claim 1, wherein The glass substrate comprises alkali-free glass, and the alkali-free glass comprises, expressed in mol % based on oxides: 64% to 69% SiO2, 10% to 15% Al2O3, 1% to 3.5% B2O3, 7% to 12% MgO.

3. The glass substrate according to claim 2, wherein The glass substrate comprises alkali-free glass, and the alkali-free glass comprises, expressed in mol % based on oxides: 65.2%~66.9% SiO2, 10.8% to 13.5% Al2O3, 1.2% to 3.5% B2O3, 7% to 12% MgO, 5% to 9.7% CaO.

4. The glass substrate according to claim 3, wherein The strain point of the alkali-free glass is 650° C. or higher, and the average thermal expansion coefficient of the alkali-free glass at 50° C. to 350° C. is 30×10 -7 / ℃~45×10 -7 / ℃.

5. The glass substrate according to claim 3, wherein The alkali-free glass contains alkali metal oxides in an amount of 0.5% or less, expressed as mol% based on oxides.

6. The glass substrate according to claim 3, wherein The glass substrate is manufactured using a float process.

7. The glass substrate according to claim 3, wherein The at least one main surface is a ground surface formed by grinding.

8. The glass substrate according to claim 7, wherein The Stdi value of the polished surface is less than 0.75, The Stdi value is a texture direction index obtained by using AFM in an observation field of 1 μm×1 μm square and at 256×256 pixels.

9. A black matrix substrate, wherein: A black matrix film is formed on at least one main surface of the glass substrate according to claim 3 .

10. A display panel, wherein: The display panel includes the black matrix substrate according to claim 9.

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