TWI706923B - glass - Google Patents

Abstract

The glass of the present invention is characterized in that it contains 55% to 80% of SiO ₂ , 11% to 30% of Al ₂ O ₃ , 0 to 3% of B ₂ O ₃ , and 0 to 3% of Li ₂ O+Na ₂ O+K ₂ O, 5% to 35% of MgO+CaO+SrO+BaO are used as the glass composition, and the strain point is higher than 700°C.

Description

glass

The present invention relates to a glass with high heat resistance. For example, it relates to a glass substrate used to produce a semiconductor crystal (Light Emitting Diode, LED) at high temperature.

For semiconductor crystals used for LEDs and the like, it is known that the higher the temperature is, the more the semiconductor characteristics are improved.

A sapphire substrate with high heat resistance is generally used in the application. In other applications, sapphire substrates are also used when semiconductor crystals are formed into films at high temperatures (for example, 700°C or higher).

[Prior Art Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 11-243229

In addition, in recent years, a technique for forming a large-area semiconductor crystal into a film has been actively studied. It is believed that this technology is also expected to be used in surface-emitting light sources of large displays.

However, for the sapphire substrate, it is difficult to achieve a large area, and it is not suitable for the application.

If a glass substrate is used instead of a sapphire substrate, it is considered that the substrate can be realized The area has been increased, but the conventional glass substrates have insufficient heat resistance, so they tend to be thermally deformed during high-temperature heat treatment.

Moreover, if the heat resistance of the conventional glass substrate is to be improved, the thermal expansion coefficient of the glass substrate will be unduly reduced, making it difficult to match the thermal expansion coefficient of the semiconductor crystal. After the semiconductor crystal is produced, the glass substrate is likely to warp, or the semiconductor The film is prone to cracks. Furthermore, if it is desired to improve the heat resistance of a glass substrate, devitrification resistance will fall, and it will become difficult to shape|mold into a flat-plate-shaped glass substrate.

The present invention is an invention made in view of the aforementioned circumstances, and its technical problem is to create glass that has high heat resistance and thermal expansion coefficient and can be formed into a flat plate shape.

After conducting various experiments repeatedly, the inventor found that the technical problem can be solved by limiting the glass composition to a predetermined range, and thus came up with the present invention. That is, the glass of the present invention is characterized in that it contains 55% to 80% of SiO ₂ , 11% to 30% of Al ₂ O ₃ , 0 to 3% of B ₂ O ₃ , and 0 to 3% in molar %. % Li ₂ O+Na ₂ O+K ₂ O and 5%~35% MgO+CaO+SrO+BaO are used as glass composition, and the strain point is higher than 700℃. Here, "Li ₂ O+Na ₂ O+K ₂ O" means the total amount of Li ₂ O, Na ₂ O, and K ₂ O. "MgO+CaO+SrO+BaO" refers to the total amount of MgO, CaO, SrO and BaO. Here, the "strain point" refers to a value measured based on the American Society for Testing and Materials (ASTM) C336 method.

In the glass composition of the present invention, the content of Al ₂ O ₃ is limited to 11 mol% or more, the content of B ₂ O ₃ is limited to 3 mol% or less, and Li ₂ O+Na ₂ O+K ₂ The content of O is limited to 3 mol% or less. As a result, the strain point rises significantly, and the heat resistance of the glass substrate can be greatly improved.

Furthermore, the glass of the present invention contains 5 mol% to 25 mol% of MgO+CaO+SrO+BaO in the glass composition. Thereby, the thermal expansion coefficient can be increased, and the devitrification resistance can be improved.

Second, the content of B ₂ O ₃ in the glass of the present invention is preferably less than 1 mol%.

Third, the content of Li ₂ O+Na ₂ O+K ₂ O in the glass of the present invention is preferably 0.2 mol% or less.

Fourth, the molar ratio (MgO+CaO+SrO+BaO)/Al ₂ O ₃ of the glass of the present invention is preferably 0.5-5. Here, "(MgO+CaO+SrO+BaO)/Al ₂ O ₃ "is a value obtained by dividing the total amount of MgO, CaO, SrO, and BaO by the content of Al ₂ O ₃ .

Fifth, the molar ratio MgO/(MgO+CaO+SrO+BaO) of the glass of the present invention is preferably less than 0.5. Here, "MgO/(MgO+CaO+SrO+BaO)" is a value obtained by dividing the content of MgO by the total amount of MgO, CaO, SrO, and BaO.

Sixth, the thermal expansion coefficient in the temperature range of 30°C to 380°C of the glass of the present invention is preferably 40×10 ^-7 /°C or higher. Here, "the coefficient of thermal expansion in the temperature range of 30°C to 380°C" refers to the average value measured with a dilatometer.

Seventh, the strain point of the glass of the present invention is preferably 800°C or higher.

Eighth, the (temperature-strain point at a high temperature viscosity of 10 ^2.5 dPa·s) of the glass of the present invention is preferably 900°C or less. Here, the "temperature at high temperature viscosity 10 ^2.5 dPa·s" refers to the value measured by the platinum ball pulling method.

Ninth, the glass of the present invention has a viscosity of 10 ^2.5 dPa at high temperature. The temperature at the viscosity of s is preferably 1750°C or lower.

Tenth, the glass of the present invention is preferably in the shape of a flat plate.

Eleventh, the glass of the present invention is preferably used as a substrate for growing semiconductor crystals.

The glass of the present invention contains 55%~80% SiO ₂ , 11%~30% Al ₂ O ₃ , 0~3% B ₂ O ₃ , 0~3% Li ₂ O+ in terms of mole% Na ₂ O+K ₂ O, 5%~35% MgO+CaO+SrO+BaO are used as glass composition. As described above, the reason for limiting the content of each component will be explained below. In addition, in the description of each component, the expression of% below refers to mole %.

The appropriate lower limit range of SiO ₂ is 55% or more, 58% or more, 60% or more, 65% or more, especially 68% or more, and the appropriate upper limit range is preferably 80% or less, 75% or less, 73% or less, 72 % Or less, 71% or less, especially 70% or less. If the content of SiO ₂ is too small, defects caused by devitrified crystals containing Al ₂ O ₃ are likely to occur, and the strain point is likely to decrease. Moreover, the high temperature viscosity will decrease, so that the liquid phase viscosity will easily decrease. On the other hand, if the content of SiO ₂ is too large, the coefficient of thermal expansion will be unduly lowered, the viscosity at high temperature will increase, the meltability will be lowered, and devitrification crystals containing SiO ₂ will easily occur.

The appropriate lower limit range of Al ₂ O ₃ is 11% or more, 12% or more, 13% or more, 14% or more, especially 15% or more, and the appropriate upper limit range is 30% or less, 25% or less, 20% or less, 18 % Or less, 17% or less, especially 16% or less. If the content of Al ₂ O ₃ is too small, the strain point is likely to decrease, or the high-temperature viscosity increases, and the meltability is likely to decrease. On the other hand, if the content of Al ₂ O ₃ is too large, devitrification crystals containing Al ₂ O ₃ are likely to be produced.

From the viewpoint of taking into account both high strain point and high devitrification resistance, the molar ratio of SiO ₂ /Al ₂ O _{3 is} preferably 2~6, 3~5.5, 3.5~5.5, 4~5.5, 4.5~5.5, especially It is 4.5~5. In addition, "SiO ₂ /Al ₂ O ₃ "is a value obtained by dividing the content of SiO ₂ by the content of Al ₂ O ₃ .

The appropriate upper limit range of B ₂ O ₃ is 3% or less, 1% or less, less than 1%, and particularly 0.1% or less. If the content of B ₂ O ₃ is too large, the strain point may be drastically lowered.

The appropriate upper limit range of Li ₂ O+Na ₂ O+K ₂ O is 3% or less, 1% or less, less than 1%, 0.5% or less, especially 0.2% or less. If the content of Li ₂ O+Na ₂ O+K ₂ O is too large, the characteristics of semiconductor crystals formed on the glass may deteriorate. In addition, the appropriate upper limit ranges of Li ₂ O, Na ₂ O, and K ₂ O are 3% or less, 1% or less, less than 1%, 0.5% or less, 0.3% or less, and particularly 0.2% or less, respectively.

The proper lower limit range of MgO+CaO+SrO+BaO is 5% or more, 7% or more, 9% or more, 11% or more, 13% or more, especially 14% or more, and the proper upper limit range is 35% or less, 30% Or less, 25% or less, 20% or less, 18% or less, 17% or less, especially 16% or less. If the content of MgO+CaO+SrO+BaO is too small, The liquidus temperature will rise significantly, devitrification crystals are likely to occur in the glass, or the high temperature viscosity will increase, and the meltability will easily decrease. On the other hand, if the content of MgO+CaO+SrO+BaO is too large, the strain point is likely to decrease, and devitrification crystals containing alkaline earth elements are likely to be generated.

The appropriate lower limit range of MgO is 0% or more, 1% or more, 2% or more, 3% or more, 4% or more, especially 5% or more, and the appropriate upper limit range is 15% or less, 10% or less, 8% or less, In particular, it is 7% or less. If the content of MgO is too small, the meltability is likely to decrease, or the devitrification of crystals containing alkaline earth elements is likely to increase. On the other hand, if the content of MgO is too large, the precipitation of devitrified crystals containing Al ₂ O ₃ is promoted, resulting in a decrease in liquid phase viscosity, or a large decrease in strain point. Furthermore, although MgO has the effect of increasing the coefficient of thermal expansion, among alkaline earth oxides, MgO has the smallest effect.

The appropriate lower limit range of CaO is 2% or more, 3% or more, 4% or more, 5% or more, 6% or more, especially 7% or more, and the appropriate upper limit range is 20% or less, 15% or less, 12% or less, 11% or less, 10% or less, especially 9% or less. If the content of CaO is too small, the meltability is likely to decrease. On the other hand, if the content of CaO is too large, the liquidus temperature rises, and devitrification crystals are likely to occur in the glass. Furthermore, compared with other alkaline earth oxides, CaO has a greater effect of improving the viscosity of the liquid phase without lowering the strain point or improving the meltability, and the effect of increasing the coefficient of thermal expansion is greater than that of MgO.

The appropriate lower limit range of SrO is 0% or more, 1% or more, especially 2% or more, and the appropriate upper limit range is 10% or less, 8% or less, 7% or less, 6% or less, 5% or less, especially 4% or less. If the content of SrO is too small, the strain point tends to decrease. On the other hand, if the content of SrO is too large, the liquidus temperature rises, devitrification crystals are likely to occur in the glass, and the meltability is likely to decrease. Furthermore, when it coexists with CaO, if the content of SrO increases, the devitrification resistance tends to decrease. Furthermore, SrO has a greater effect of increasing the coefficient of thermal expansion than MgO or CaO.

The appropriate lower limit range of BaO is 0% or more, 3% or more, 4% or more, 5% or more, 6% or more, 7% or more, especially 8% or more, and the appropriate upper limit range is 15% or less, 12% or less, 11% or less, especially 10% or less. If the content of BaO is too small, the strain point or thermal expansion coefficient is likely to decrease. On the other hand, if the content of BaO is too large, the liquidus temperature rises, and devitrification crystals are likely to occur in the glass. Moreover, the meltability is easily reduced. Furthermore, BaO has the greatest effect of increasing the coefficient of thermal expansion or strain point among alkaline earth metal oxides.

From the viewpoint of improving the resistance to devitrification, the lower limit range of the molar ratio of MgO/CaO is preferably 0.1 or more, 0.2 or more, 0.3 or more, especially 0.4 or more, and the upper limit range is preferably 2 or less, 1 or less, and 0.8 or less , 0.7 or less, especially 0.6 or less. In addition, "MgO/CaO" refers to the value obtained by dividing the content of MgO by the content of CaO.

From the viewpoint of improving the resistance to devitrification, the lower limit range of the molar ratio BaO/CaO is preferably 0.2 or more, 0.5 or more, 0.6 or more, 0.7 or more, especially 0.8 or more, and the upper limit is preferably 5 or less and 4.5 or less , 3 or less, 2.5 or less, especially 2 or less. In addition, "BaO/CaO" refers to the value obtained by dividing the content of BaO by the content of CaO.

In view of the balance between strain point and meltability, the lower limit range of molar ratio (MgO+CaO+SrO+BaO)/Al ₂ O ₃ is preferably 0.5 or more, 0.6 or more, 0.7 or more, especially 0.8 or more, and the upper limit is preferably It is 5.0 or less, 4.0 or less, 3.0 or less, 2.0 or less, 1.5 or less, 1.2 or less, especially 1.1 or less.

The molar ratio MgO/(MgO+CaO+SrO+BaO) is preferably 0.6 or less, less than 0.5, 0.4 or less, 0.3 or less, 0.2 or less, and particularly 0.1 or less. MgO is a component that drastically lowers the strain point, and its effect of lowering the strain point is remarkable in a region where the content of MgO is small. Therefore, it is preferable that the content ratio of MgO in the alkaline earth metal oxide is small.

7×[MgO]+5×[CaO]+4×[SrO]+4×[BaO] is preferably 100% or less, 90% or less, 80% or less, 70% or less, 65% or less, especially 60% the following. Alkaline earth metal elements all have the effect of lowering the strain point, but the smaller the ion radius of the element, the greater the effect. In this way, the upper limit range of 7×[MgO]+5×[CaO]+4×[SrO]+4×[BaO] is limited so as not to increase the proportion of alkaline earth elements with a small ion radius , You can give priority to increasing the strain point. In addition, [MgO] refers to the content of MgO, [CaO] refers to the content of CaO, [SrO] refers to the content of SrO, and [BaO] refers to the content of BaO. Furthermore, "7×[MgO]+5×[CaO]+4×[SrO]+4×[BaO]” means 7 times [MgO], 5 times [CaO], 4 times [SrO], and 4 times the total amount of [BaO].

21×[MgO]+20×[CaO]+15×[SrO]+12×[BaO] is preferably 200% or more, 210% or more, 220% or more, 230% or more, 240% or more, 250% or more, Especially 300%~1000%. Alkaline earth metal elements all have the effect of improving meltability, but the smaller the ion radius of the element, the greater the effect. By this, if not to leave By increasing the proportion of alkaline earth elements with a small sub-radius, limiting the lower limit range of 21×[MgO]+20×[CaO]+15×[SrO]+12×[BaO] can give priority to improving the melting property . However, if 21×[MgO]+20×[CaO]+15×[SrO]+12×[BaO] is too large, the strain point may decrease. Furthermore, "21×[MgO]+20×[CaO]+15×[SrO]+12×[BaO]" means 21 times [MgO], 20 times [CaO], 15 times [SrO] And 12 times the total amount of [BaO].

In addition to the above-mentioned components, the following components may be introduced into the glass composition.

ZnO is a component that improves the meltability. However, if ZnO is contained in a large amount in the glass composition, the glass tends to lose clarity and the strain point tends to decrease. Thereby, the content of ZnO is preferably 0~5%, 0~3%, 0~0.5%, 0~0.3%, especially 0~0.1%.

ZrO ₂ is a component that improves Young's modulus. The content of ZrO ₂ is preferably 0~5%, 0~3%, 0~0.5%, 0~0.2%, especially 0~0.02%. If the content of ZrO ₂ is too large, the liquidus temperature will rise, and devitrification crystals of zircon will easily precipitate.

TiO ₂ is a component that reduces high-temperature viscosity and improves meltability, and is a component that suppresses solarization. However, if a large amount of TiO ₂ is contained in the glass composition, the glass is likely to be colored. Accordingly, the content of TiO ₂ is preferably 0~5%, 0~3%, 0~1%, 0~0.1%, especially 0~0.02%.

P ₂ O ₅ is a component that improves the devitrification resistance. However, if this P ₂ O ₅ is contained in a large amount in the glass composition, the glass is likely to separate into phases and become milky white, and the water resistance may be greatly reduced. Thus, the content of P ₂ O ₅ is preferably 0~5%, 0~4%, 0~3%, 0~less than 2%, 0~1%, 0~0.5%, especially 0~0.1%.

SnO ₂ is a component that has a good clarification effect in a high-temperature region and is a component that reduces high-temperature viscosity. The content of SnO ₂ is preferably 0~1%, 0.01%~0.5%, 0.01%~0.3%, especially 0.04%~0.1%. If the content of SnO ₂ is too large, devitrification crystals of SnO ₂ are likely to precipitate.

As described above, for the glass of the present invention, it is preferable to add SnO ₂ as a fining agent, but as long as the glass characteristics are not impaired, CeO ₂ , SO ₃ , C, metal powder (for example, Al, Si, etc.) as clarifying agents.

As ₂ O ₃ , Sb ₂ O ₃ , F, and Cl also function effectively as fining agents. The glass of the present invention does not exclude the inclusion of these components, but from the environmental point of view, the contents of these components are relatively high. It is preferably less than 0.1%, especially less than 0.05%.

In the case where 0.01% to 0.5% of SnO _{2 is} contained, if the content of Rh ₂ O ₃ is too large, the glass is likely to be colored. Furthermore, Rh ₂ O ₃ may be mixed in from the platinum manufacturing container. The content of Rh ₂ O ₃ is preferably 0 to 0.0005%, more preferably 0.00001% to 0.0001%.

SO ₃ is a component mixed from the raw material as an impurity. However, if the content of SO ₃ is too large, bubbles called reboil are generated during the melting or molding process, which may cause defects in the glass. The suitable lower limit range of SO ₃ is 0.0001% or more, and the suitable upper limit range is 0.005% or less, 0.003% or less, 0.002% or less, especially 0.001% or less.

The content of rare earth oxides (Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and other oxides) is preferably less than 2%, 1% or less, less than 0.5%, especially less than 0.1%. In particular, the content of La ₂ O ₃ +Y ₂ O ₃ is preferably less than 2%, less than 1%, less than 0.5%, and especially less than 0.1%. The content of La ₂ O ₃ is preferably less than 2%, less than 1%, less than 0.5%, and especially less than 0.1%. If the content of rare earth oxides is too large, batch costs are likely to increase. Furthermore, "Y ₂ O ₃ + La ₂ O ₃ "is the total amount of Y ₂ O ₃ and La ₂ O ₃ .

The glass of the present invention preferably has the following characteristics.

The density is preferably 3.20 g/cm ³ or less, 3.00 g/cm ³ or less, 2.90 g/cm ³ or less, especially 2.80 g/cm ³ or less. If the density is too high, it is difficult to reduce the weight of electronic components.

The thermal expansion coefficient in the temperature range of 30°C to 380°C is preferably 40×10 ^-7 /°C or higher, 42×10 ^-7 /°C or higher, 44×10 ^-7 /°C or higher, 46×10 ^-7 /°C or higher , Particularly preferably 48×10 ^-7 /℃~80×10 ^-7 /℃. If the thermal expansion coefficient in the temperature range of 30°C to 380°C is too low, the thermal expansion coefficient of the semiconductor crystal (for example, nitride semiconductor crystal) and the glass substrate will not match, the glass substrate is likely to warp, or the semiconductor crystal is likely to crack.

The strain point is preferably higher than 700°C, higher than 750°C, higher than 780°C, higher than 800°C, higher than 810°C, higher than 820°C, particularly preferably 830°C to 1000°C. If the strain point is too low, the heat treatment temperature cannot be increased, and it is difficult to improve the semiconductor characteristics of the semiconductor crystal.

The SiO ₂ -Al ₂ O ₃ -RO (RO means alkaline earth metal oxide) glass of the present invention is generally difficult to melt. Therefore, the improvement of meltability becomes a problem. If the meltability is increased, the defect rate due to bubbles, foreign substances, etc. will decrease, and therefore, high-quality glass substrates can be supplied in large quantities at low cost. On the other hand, if the high temperature viscosity is too high, it is difficult to use the melting step to promote outgassing. With this, the viscosity at high temperature is 10 ^2.5 dPa. The temperature at s is preferably 1750°C or lower, 1700°C or lower, 1680°C or lower, 1670°C or lower, 1650°C or lower, especially 1630°C or lower. Furthermore, the viscosity at high temperature is 10 ^2.5 dPa. The temperature at s corresponds to the melting temperature, and the lower the temperature, the better the meltability.

From the viewpoint of both high strain point and low melting temperature, (temperature-strain point at 10 ^2.5 dPa·s) is preferably 900°C or lower, 850°C or lower, and especially 800°C or lower.

In the case of forming into a flat plate shape, devitrification resistance becomes important. In consideration of the forming temperature of the SiO ₂ -Al ₂ O ₃ -RO-based glass of the present invention, the liquidus temperature is preferably 1450° C. or lower, 1400° C. or lower, particularly 1300° C. or lower. Moreover, the viscosity of the liquid phase is preferably 10 ^3.0 dPa. s or more, 10 ^3.5 dPa. s or more, especially 10 ^4.0 dPa. s above. In addition, "liquid phase temperature" means that the glass powder that has passed through a 30 mesh (500 μm) standard sieve and remains on a 50 mesh (300 μm) standard sieve is placed in a platinum boat. The temperature gradient furnace is kept for 24 hours, and the temperature at the time of crystal precipitation is measured. The "liquid phase viscosity" refers to the value obtained by measuring the viscosity of the glass at the liquidus temperature by the platinum ball pulling method.

The glass of the present invention can be formed by various forming methods. For example, the glass substrate can be formed by an overflow down draw method, a slot down draw method, a redraw method, a float method, a roll out method, and the like. Furthermore, if the glass substrate is molded by the overflow down-draw method, it is easy to produce a glass substrate with high surface smoothness.

When the glass of the present invention has a flat plate shape, the plate thickness is preferably 1.0 mm or less, 0.7 mm or less, 0.5 mm or less, especially 0.4 mm or less. The smaller the board thickness, the easier it is to reduce the weight of electronic components. On the other hand, the smaller the plate thickness, the easier it is for the glass substrate to bend. However, the glass of the present invention has a Young's modulus or higher than the Young's modulus (specific Young's modulus), so it is less likely to cause defects due to deflection. . Furthermore, the plate thickness can be adjusted by the flow rate during forming, the plate pulling speed, etc.

In the glass of the present invention, if the β-OH value is reduced, the strain point can be increased. The β-OH value is preferably 0.45/mm or less, 0.40/mm or less, 0.35/mm or less, 0.30/mm or less, 0.25/mm or less, 0.20/mm or less, especially 0.15/mm or less. If the β-OH value is too large, the strain point is likely to decrease. Furthermore, if the β-OH value is too small, the meltability is likely to decrease. Thereby, the β-OH value is preferably 0.01/mm or more, especially 0.05/mm or more.

The following methods can be cited as methods for reducing the β-OH value. (1) Choose raw materials with low water content. (2) Adding components (Cl, SO ₃ etc.) that reduce the amount of water in the glass. (3) Reduce the amount of moisture in the furnace environment. (4) Perform N ₂ bubbling in molten glass. (5) Use a small melting furnace. (6) Speed up the flow of molten glass. (7) The electric melting method is adopted.

Here, the "β-OH value" refers to a value obtained by measuring the transmittance of glass using a Fourier Transform Infrared Spectrometer (FT-IR) and using the following equation.

β-OH value=(1/X)log(T ₁ /T ₂ )

X: Glass wall thickness (mm)

T ₁ ：Transmittance under the reference wavelength of 3846cm ^-1 (%)

T ₂ : The minimum transmittance (%) at the hydroxyl absorption wavelength near 3600cm ^-1

[Example]

Hereinafter, the present invention will be described in detail based on examples. In addition, the following examples are only examples. The present invention is not limited to the following examples at all.

Tables 1 to 4 show examples of the present invention (sample No. 1 to No. 63).

Each sample was produced in the following manner. First, a glass batch prepared by mixing glass raw materials so as to become the glass composition in the table is put into a platinum crucible and melted at 1600°C to 1750°C for 24 hours. When melting the glass batch, stir using a platinum stirrer (stirrer) to homogenize the glass batch. Next, the molten glass is flowed out onto the carbon plate and formed into a flat plate shape. For each sample obtained, the density ρ, the coefficient of thermal expansion α, the strain point Ps, the annealing point Ta, the softening point Ts, and the viscosity at high temperature 10 ^4.0 dPa were evaluated. The temperature at s, the viscosity at high temperature is 10 ^3.0 dPa. The temperature at s, the viscosity at high temperature is 10 ^2.5 dPa. s temperature, liquid phase temperature TL, liquid viscosity logηTL.

The density ρ is a value measured by the well-known Archimedes method.

The coefficient of thermal expansion α is an average value measured in a temperature range of 30°C to 380°C with a dilatometer.

The strain point Ps, annealing point Ta, and softening point Ts are values measured in accordance with ASTM C336 or ASTM C338.

The viscosity at high temperature is 10 ^4.0 dPa. The temperature at s, the viscosity at high temperature is 10 ^3.0 dPa. The temperature at s, the viscosity at high temperature is 10 ^2.5 dPa. The temperature at s is the value measured by the platinum ball pulling method.

Liquidus temperature TL is to pulverize each sample, put the glass powder that has passed through a 30-mesh (500μm) standard sieve and remains on a 50-mesh (300μm) standard sieve into a platinum boat, and keep it in a temperature gradient furnace for 24 hours After taking out the platinum boat, the temperature at which devitrification (devitrification crystal) was seen in the glass. Liquid viscosity logηTL is the method of pulling platinum ball The value obtained by measuring the viscosity of the glass at the liquidus temperature TL.

The β-OH value is a value calculated based on the above formula.

Tables 1 to 4 show that the strain point and thermal expansion coefficient of samples No.1 to No.63 are high, and they have devitrification resistance that can be formed into a flat plate shape. From this, it is considered that samples No. 1 to No. 63 are suitable as substrates for crystal growth of semiconductor crystals (for example, nitride semiconductor crystals, especially gallium nitride semiconductor crystals) at high temperatures.

[Industrial availability]

The glass of the present invention has a high strain point and a high thermal expansion coefficient, and has good devitrification resistance. Therefore, the glass of the present invention is not only suitable for substrates for making semiconductor crystals at high temperatures, but also suitable for display substrates such as organic light emitting diode (Organic Light Emitting Diode, OLED) displays and liquid crystal displays, and is particularly suitable as A display substrate driven by Low Temperature Poly Silicon (LTPS) and Thin Film Transistor (TFT).

Claims (11)

A glass characterized in that it contains 55% to 80% of SiO ₂ , 12.7% to 30% of Al ₂ O ₃ , 0 to 1% of B ₂ O ₃ , and 0 to 3% of Li in terms of mole% ₂ O+Na ₂ O+K ₂ O, 5%~35% of MgO+CaO+SrO+BaO, molar ratio (MgO+CaO+SrO+BaO)/Al ₂ O ₃ below 1.33 are used as glass composition, and The strain point is higher than 700°C, and the content of BaO in the glass composition is 2.5-15 mol%. For the glass described in item 1 of the scope of patent application, the content of B ₂ O ₃ is less than 1 mol%. For the glass described in item 1 or item 2 of the scope of patent application, the content of Li ₂ O+Na ₂ O+K ₂ O is 0.2 mol% or less. For the glass described in item 1 or item 2 of the scope of patent application, the molar ratio (MgO+CaO+SrO+BaO)/Al ₂ O ₃ is 0.5 to 1.33. For the glass described in item 1 or item 2 of the scope of the patent application, the molar ratio MgO/(MgO+CaO+SrO+BaO) is less than 0.5. For the glass described in item 1 or item 2 of the scope of patent application, the coefficient of thermal expansion in the temperature range of 30°C to 380°C is 40×10 ^-7 /°C or more. For the glass described in item 1 or item 2 of the scope of patent application, the strain point is above 800°C. Such as the glass described in item 1 or item 2 of the scope of patent application, wherein (temperature-strain point at high temperature viscosity 10 ^2.5 dPa·s) is below 900°C. Such as the glass described in item 1 or item 2 of the scope of patent application, wherein the viscosity at high temperature is 10 ^2.5 dPa. The temperature when the viscosity of s is 1750°C or less. The glass according to item 1 or item 2 of the scope of patent application, wherein the glass is in the shape of a flat plate. The glass described in item 1 or item 2 of the scope of patent application, wherein the glass is used as a substrate for making semiconductor crystals.