TW200825033A - Alkali-free glass substrate and its production method - Google Patents

Abstract

To provide an alkali-free glass substrate which has low dispersion among individual products with respect to thermal shrinkage and to provide its production method. Provided is an alkali-free glass substrate characterized in that it has a thermal shrinkage of not less than 50 ppm in terms of an absolute value when subjected to a treatment including raising its temperature from ordinary temperature at a rate of 10 DEG C/min, keeping its temperature at 450 DEG C for 10 hr, and lowering its temperature at a rate of 10 DEG C/min (namely, when heat-treated according to the temperature schedule shown in Fig. 1).

Description

200825033 IX. Description of the Invention: [Technical Fields of the Invention] The present invention relates to various types such as a flat panel display substrate such as a liquid crystal display or an el display, a charge coupled device (CCD), and a double-closed solid-state imaging device (CIS). A glass-free substrate of a substrate such as an image sensor, a hard disk, or a filter. [Prior Art] Conventionally, a glass substrate has been widely used as a flat display substrate such as a liquid crystal display or an EL display. In particular, electronic devices such as thin film transistor active matrix liquid crystal displays (TFT_LCDs) are generally used for car navigation, digital camera finder windows, personal computer monitors, and τν applications because of their thinness and low power consumption. . In order to drive a liquid crystal display, it is necessary to form a driving element typified by a TF-butyl element on a glass substrate. In the manufacturing process of the TFT element, a transparent conductive film, an insulating film, a semiconductor film, a metal film, or the like is formed on the glass substrate. Further, in the photolithography etching step, the glass substrate is treated by various heat treatments and drug treatments. For example, in a TFT type active matrix liquid crystal display, an insulating film and a transparent conductive film are formed on a glass substrate. Further, in the photolithography etching step, a large amount of amorphous germanium or polycrystalline germanium TF (film transistor) is formed on the glass substrate. In this manufacturing step, the glass substrate is subjected to a heat treatment of 3 Torr to 6 Torr C, and is treated with various chemicals such as sulfuric acid, hydrochloric acid, an alkali solution, hydrofluoric acid, and buffered hydrofluoric acid. Therefore, in the glass substrate for a TFT liquid crystal display, it is required to have the following characteristics: 118502.doc 200825033 (1) When the metal oxide is contained in the glass, in the heat treatment, the test ions are carried into the semiconductor material after the film formation, resulting in The alkali metal oxide should not be contained above the film properties. shell

(2) Excellent resistance to chemicals such as acid, test, etc. used in the photolithography (fourth) step. T (3) In the steps of film formation, annealing, etc., the glass substrate is exposed to high temperature.

The heat shrinkage rate of the glass substrate is preferably small. That is to say, when the heat shrinkage rate is large, the offset of the circuit pattern formed on the substrate occurs. From the reduction of the heat (four) rate (four), it is more advantageous to have a higher strain point of the glass. In addition to the above, the glass substrate for TFT liquid crystal display is required to have the following characteristics: (4) Excellent devitrification property. In the glass (four) step and the molding step, foreign matter does not occur in the glass. In particular, in the case where the glass is formed by a down-draw method such as an overflow down-draw method, the devitrification resistance of the glass is very important. When the glass forming temperature is considered, the liquidus temperature is required to be 12 Torr. 〇The following. (5) In order to make the liquid crystal display lighter, the density should be lower. In particular, the glass substrate mounted on the notebook PC has a relatively high requirement for weight reduction, and specifically requires 2.50 g/cm3 or less. ^ (6) The flatness of the surface is high. For example, a liquid crystal display performs a function of a shutter on a liquid crystal layer sandwiched between two thin glass substrates, and this layer is displayed by being blocked or penetrated by light. This liquid crystal layer usually maintains a very thin thickness of a few (7) to a dozen. The flatness of the surface of the m-glass substrate, especially the so-called ridge-level unevenness, is likely to affect the thickness of the liquid crystal layer (called cell gap) H8502.doc 200825033, and when the surface ripple is large, it may become uneven display. The cause of the bad. (7) The corrugation of the glass substrate is small. In recent years, in the liquid crystal display, since the cell gap tends to be thinner toward the purpose of high-speed response and high definition, the reduction of the ripple of the surface of the glass substrate used here is more and more important. The most effective way to reduce the corrugation of the surface of the glass substrate is to precisely polish the surface of the formed glass substrate, but (4) in this method, the glass

l, the manufacturing cost of the substrate will become very high. Therefore, at present, a glass substrate having a small corrugation surface which is formed as much as possible by a method such as an overflow down-draw method or a float method is usually used in the case of no grinding, or after being applied with extremely light grinding (contact polishing). . To meet these characteristics, document 1). There has been a proposal for various types of glass substrates. For example, the heat shrinkage rate of the glass substrate is as small as possible as described above. The heat shrinkage rate of the substrate is gradually adopted by the technique of riding the mask by the reticle when forming the circuit. As a result, the problem of pattern shift can be solved even if the glass substrate of the heat shrinkage rate is not filled. The iV of this technology, 'requires the thermal shrinkage rate between the glass substrates, no large error. ... ... The heat shrinkage rate of the soil plate will be affected by the forming conditions of the glass field, especially the cold part speed H in the manufacturing process towel It is difficult to maintain the cooling rate at all times. Therefore, even in the case of the glass substrates manufactured at the same time, the heat shrinkage rate of the glass substrates is not necessarily constant, and the present invention is aimed at providing the heat shrinkage rate. The present invention has been found to be the result of various investigations by the inventors of the present invention. The faster the cooling rate, the more the change in the heat shrinkage rate is.

That is to say, 'the non-test glass substrate of this kind is characterized by heating at normal temperature at the rate of [generation, minute, to maintain the temperature of 45 (rc is kept for 1 hour, at the speed of i〇ec / minute P " dish (as shown in Figure 1 In the case of heat treatment of the thermometer, the absolute value of the heat shrinkage rate is 50 ppm or more. In addition, this patent describes the so-called "no glass", which means alkali metal oxide (Li2〇, Na2〇, (4) or less glass. X, "absolute value of heat shrinkage rate" is the value of part I (near the center of gravity) in the base. Further, the alkali-free glass substrate of the present invention is characterized by a strain point of 630 to 655 C and a temperature of 1 常 from normal temperature. The speed of ac/min is increased to maintain the temperature of 45 (TC is kept for 10 hours, and the temperature is reduced by 1 〇r/min (the heat treatment rate is shown by the thermometer shown in Fig.). The absolute value of the heat shrinkage is 6 〇 ppma. Further, the alkali-free glass substrate of the present invention is characterized by a strain point of 655 to 680 ° C, and is heated by a normal temperature at a rate of 1 (TC/min, maintaining the temperature at 450 ° C for 10 hours, at 1 〇 r / The speed of the sub-speed is reduced (the heat treatment of the thermometer shown in Fig.!) is the absolute value of the heat shrinkage rate of 5 〇ppm. The method for manufacturing the non-test glass substrate of the present invention is characterized in that it is a method for melting and forming a glass raw material to produce an alkali-free glass substrate, and in the cooling process of forming a belt 118502.doc 200825033, The temperature range from the cold point to the temperature drop (the cold cooling point ~ (Xu cold point _1 〇〇. 温度 temperature range) average cooling rate is 300C / min or more. Also, the so-called "flat eight" 叮口月十The average cooling rate is the time during which the central portion of the width of the glass is passed through the temperature range from the cold point to the temperature of the 〇〇t (the cold zone), and the temperature difference in the cold zone is utilized. (=l〇〇t) is divided by the speed obtained by the required time. The dish is further characterized in that the method for producing the glass-free substrate of the present invention is characterized in that the glass material is refining and forming to form strain points. For the 630~6 method of hunger-free glass substrate', during the cooling process during forming, the average cooling rate of the temperature range from Xu cold to 100 C is 35 〇. " Moreover, the alkali-free glass of the invention The method for producing a glass substrate is characterized in that it is a method of squeezing and forming a glass material to produce a glass-free substrate having a strain point of 655 to 10 (c), and in the cooling process during forming, the cold point is from the cold point to The average cooling rate in the temperature range up to the loo C IV dish is C/min or more. The glass-free substrate of the present invention is characterized in that it is produced by the above-mentioned party. Effect of the Invention The glass substrate of the present invention is on the substrate. The error of the heat shrinkage rate between the two is small. Therefore, when the TFT circuit is used, when the mask is used for correction, the shrinkage of the glass substrate can be contracted by an ancient J... The straight remains, but Gao Liang Stable to form a pattern. Further, according to the production method of the present invention, the above-mentioned glass base 118502.doc 200825033 plate can be easily produced. Moreover, by increasing the speed of the pull plate to increase the cooling rate, the amount of glass substrate produced per unit time can be greatly increased. Moreover, if the flow rate of the glass supplied to the forming device is reduced while increasing the speed of the drawing plate, the plate thickness can be made smaller (specifically, it is 0.6 mm or less, 〇·5 mm or less, 〇·4 mm or less, especially Glass substrate of 0.3 mm or less). [Embodiment] First, a glass substrate according to the present invention will be described. The heat shrinkage rate of the glass substrate is about the cooling rate at which the sheet glass is formed. According to the investigation by the inventors of the present invention, as shown in Fig. 2, it was confirmed that the heat shrinkage rate of the plate glass cooled by the high cooling rate was large, and the heat shrinkage rate of the plate glass cooled by the low speed was small. On the other hand, even if the cooling rate of the plate glass cooled by the high cooling rate is somewhat changed, the heat shrinkage rate hardly changes. On the other hand, if the cooling rate of the plate glass cooled by the low speed is slightly changed, the heat shrinkage rate greatly changes. Specifically, the absolute shrinkage rate of the alkali-free glass substrate is 5 〇叩 (5) or more, preferably 60 ppm or more, and the heat shrinkage rate hardly changes even if the cooling rate is changed. The heat shrinkage of the glass substrate is corrected by the reticle. The change of the heat shrinkage rate when the cooling rate is changed to 60 ° C /min by the average cooling rate in the temperature range from the cold point to 1 〇〇C. When the amount is 3 ppm or less, the formation of the pattern can be stably performed. Further, when the absolute value of the heat shrinkage ratio of the glass substrate is the same, the higher the strain point of the glass substrate, the smaller the amount of change in the heat shrinkage rate tends to be. Therefore, it can be said that the higher the strain point of the glass, the better. In the case of a glass with a strain point of 630 to 655 C, in order to obtain a cooling rate of 118,502.doc 200825033, a glass substrate having a thermal shrinkage change of less than 3 ppm at 60 ° C/min, as long as the glass substrate is thermally shrunk The absolute value of the rate can be set to 6 〇 ppm or more. In order to control the amount of change in the heat shrinkage rate to be 2 ρρπι or less, the absolute value of the heat shrinkage rate may be set to 63 ppm or more, and it may be set to 66 ppm or more in order to be controlled under the work (5). As described above, the more the heat shrinkage rate of the glass substrate is increased, the more efficient the heat shrinkage rate exceeds i 〇〇 ppm, and the correction of the mask becomes difficult. Therefore, the absolute value of the heat recovery rate of the glass substrate is preferably less than 100 ppm. Further, in the case of a glass having a strain point of 655 to 680 ° C, in order to obtain a glass substrate having a heat shrinkage rate change of 3 ppm or less when the cooling rate is changed to 60 t /min, the absolute value of the heat shrinkage rate of the glass substrate is set. It can be 5 〇卯 (5) or more. In order to control the amount of change in the heat shrinkage rate to 2 ppm or less, the absolute value of the heat shrinkage rate may be set to 53 ppm or more, and the control may be set to 55 ppm or more in order to be i or less. Further, in such a glass substrate, the absolute value of the heat shrinkage rate of the glass substrate is preferably 100 ppm or less for the same reason as described above. The alkali-free glass constituting the glass substrate of the present invention may be any glass such as quartz glass, borosilicate glass or aluminosilicate glass as long as it is suitable for the glass to be used. Among them, it is preferable to use a down-draw method, in particular, a glass formed by an overflow down-drawing method. That is to say, in the case of the down-draw method, the cooling zone (cold furnace) in the forming step is extremely short compared to the method, and it is easy to increase the average cooling rate in this temperature zone. Therefore, it is easy to increase the heat shrinkage rate of the glass. X, one of the following pull-up methods, the surface quality of the glass substrate formed by the overflow down-drawing method is superior, and has the advantages that it is not necessary to be ground, that is, 118502.doc -12-200825033 can be used. Further, since the glass substrate formed by the down-draw method is pulled in the vertical direction, the influence of the convection is affected. Therefore, compared with the float method in which the sheet is pulled in the horizontal direction, the cold portion speed is less stable, and the heat shrinkage rate is liable to cause an error. Therefore, by increasing the absolute value of the heat shrinkage rate of the glass, the heat shrinkage rate which has been difficult to achieve in the past can be achieved. That is to say, in the case of the following glass formed by the draw method, it can be said that the advantages of applying the present invention are large.

Further, for a large-sized glass substrate, for example, a substrate having a short side of 15 Å or more, particularly a substrate having a short side of 1 800 mm or more, has a stricter basis for the error of the heat shrinkage rate. In other words, in the case where the amount of change in the heat shrinkage rate is the same, the glass substrate of the type of the type of the glass substrate has a larger dimensional change due to heat shrinkage than the small substrate. Therefore, if the absolute value of the heat shrinkage ratio can be increased, even the large substrate 'I can reduce the error in dimensional change. Therefore, in the case of a large glass substrate, it can be said that the advantages of applying the present invention are large. The glass which can be formed by the down-draw method, for example, in the case of the overflow down-draw method, has a liquid phase viscosity of 10. Above pa·s, it is best to... ~· s above, glass. Further, the viscosity of the liquid phase is the viscosity at the time of crystallization, and the higher the viscosity of the liquid phase. When the glass is formed, the devitrification becomes more difficult, and the easier it is to manufacture. Further, as a glass suitable for use in a liquid crystal display substrate, it may be exemplified as having a negative 〇/〇, containing Si〇2 5〇~7〇%, A12〇3 j~, ho] 〇~ grab, MgO 〇~30% , Ca〇0~30%, Sr〇〇~3()%, Ba〇0~30%, 10~20% 0~15%, preferably in mass%, containing SiO 50 50~70%, A1203, B2〇3 3~15%, MgO 0~15%, Ca0 〇~15%, Sr〇

An aluminosilicate having an BaO 〇~15% composition is an alkali-free glass. Here, a glass substrate satisfying the required characteristics of the above (1) to (7) can be obtained in the vicinity of 118502.doc 13 200825033. In this composition range, it is desirable to obtain a strain point of 630 to 655. (: The glass 丨 升 y, for example, as long as the mass %, contains 2 5 〇 ~ 65%, Al 2 〇 3 1 0 ~ 20%, 5 〜 1 ς ο / ',

5/〇, Mg〇 〇~5%, Ca〇 〇~1〇〇/0, SrO 〇~10% ' Bao 〇~15% ’ is preferably in mass %, containing si〇2

65% Al2〇3 12^17% ^ b2〇3 5^13% > MgO 0^2% ^ CaO 3~9%, SrO 4~10〇乂, r\ ^ a〇0~ι〇% It can be selected as appropriate. The reason why the composition II If] μ, +, f, ^ is defined as described above is as follows.

Si〇2 is a component of the network formation of glass. When the content of Si〇2 is more than 65%, the viscosity of the dish is increased, the meltability is deteriorated, and the devitrification property is also deteriorated, which is not preferable. When the amount is less than 5%, the chemical durability is deteriorated, so it is not desirable. The 〇3 series is used to increase the composition of the strain point. When the content of Al2〇3 is more than 2% by weight, the devitrification property and the durability of the chemical for buffering hydrofluoric acid are deteriorated, so that it is not desirable. When it is less than 10%, the strain point is lowered, which is not preferable. More preferably, it is 12% or more and less than 17.7%. Eight (10) has the function of a refining agent to improve the meltability of the glass. The BA contains " at 15%, the strain point will reduce the deterioration of the quality, so it is not ideal. When the amount is less than 5%, the smelting property and the devitrification property are as low as the chemical durability of the buffered hydrofluoric acid, so that it is not more than 5% and 13% or less. Heart again

The Mg-based system reduces the high-temperature viscosity and improves the composition of the glass. (4) When the content is more than 5%, the devitrification is deteriorated, and the durability of the I18502.doc M-200825033, which is a chemical for the buffer gas, is also deteriorated, which is not preferable. More preferably less than 2%.

Similarly to MgO, CaO also lowers the high-temperature viscosity and improves the meltability of the glass. When the content of CaO is more than 1% by weight, the devitrification property is deteriorated, and the chemical durability to the buffered hydrofluoric acid is also deteriorated, which is not preferable. More preferably 3% or more and 9% or less.

SrO is a component that improves devitrification and chemical durability. When the content of Sr〇 is more than 10%, the density becomes large, and the high-temperature viscosity is increased, and the smelting property is deteriorated, which is not preferable. More preferably 4% or more and 10% or less.

BaO is also a component that increases devitrification and chemical durability as well as SrO. When the content of BaO is more than 15%, the density becomes large, the high-temperature viscosity is increased, and the meltability is deteriorated, which is not preferable. More preferably less than 1%. Further, it is desirable to obtain a glass having a strain point of 655 to 680 ° C, for example, by mass 〇 /. Calculated, containing Si〇2 5〇~65〇/〇, Ai2〇3 10~2〇%,

B203 5~15%, MgO 〇~5%, CaO 0~10%, SrO 0~10%, BaO 〇~5°/. , preferably in mass %, containing Si〇2 5〇~65%, Al2〇3

It is preferable to appropriately select 14 to 190/〇, B2〇3 7 to 15%, MgO 0 to 2%, CaO 3 to 10%, SrO 0 to 5%, and BaO 〇 to 2%. The reason why the composition range is defined in the above manner is as follows.

Si〇2 is a component of the network formation of glass. When the content of Si〇2 is more than 65 %, the viscosity at room temperature is increased, the meltability is deteriorated, and the devitrification property is also deteriorated, which is not preferable. When the temperature is less than 50%, the chemical durability is deteriorated, so it is not desirable.

Al2〇3 is used to increase the composition of the strain point. When the content of Al2〇3 is more than 10%, the devitrification and the durability of the chemical for buffering hydrofluoric acid are deteriorated, so it is ignored. 118502.doc 15 200825033 Imagine. When it is less than 20 / 〇, the strain point will decrease, so it is not ideal. More preferably (4) / 〇 above 19%. The B2〇3 system has a function as a solvent to improve the melting property of the glass. When the content of bismuth in B2〇3 is more than 15%, the strain point is lowered, and the chemical properties of hydrochloric acid are deteriorated, which is not preferable. When the amount is less than 5%, the meltability and the devitrification property are deteriorated, and the chemical durability to the buffered hydrofluoric acid is also deteriorated, which is not preferable. More preferably, it is 7% or more and 15% or less.

MgO system reduces the viscosity of high temperature and improves the composition of the glass. When the content of Mg〇 is more than 5%, the devitrification property is deteriorated, and the chemical durability of the buffered hydrofluoric acid is also deteriorated, which is not preferable. More preferably less than 2%.

Similarly to MgO, CaO also lowers the high-temperature viscosity and improves the meltability of the glass. When the content of CaO is more than 1% by weight, the devitrification property is deteriorated, and the chemical durability to the buffered hydrofluoric acid is also deteriorated, which is not preferable. More preferably 3% or more and 10% or less.

SrO is a component that improves devitrification and chemical durability. When the content of Sr〇 is more than 10 / 〇, the initial degree becomes large, the viscosity at room temperature increases, and the smelting property is deteriorated, so it is not ideal. More preferably 5% or less.

BaO is also a component that increases devitrification and chemical durability as well as SrO. When the content of BaO is more than 5%, the density becomes large, the high-temperature viscosity is increased, and the meltability is deteriorated, which is not preferable. More preferably less than 2%. Next, the manufacturing method relating to the present invention will be described. First, the glass raw materials of the desired composition are condensed. When the glass raw materials are blended, the glass raw materials such as oxides, nitrates, carbonates, and the like are weighed and mixed into a glass composition having characteristics suitable for the use thereof, i.e., I18502.doc 200825033. Although glass type such as quartz glass, butterfly (four) salt glass, and (iv) acid salt glass is not particularly affected, it is preferable to use a down-draw method, in particular, a glass formed by an overflow down-draw method. The glass which can be formed by the down-draw method is, for example, in the case of the 35-stream down-draw method, and has a liquidus viscosity of 1 〇 45 Pa · s or more, preferably 105. 〇 Pa · s or more.

As a glass composition suitable for the use of the liquid crystal display substrate, as described above, it may include, by mass%, 50% to 70% of Si〇2, Ai2〇3 1 to 20%, B2〇3 〇 15%, and MgO 〇. 〜30%, Ca〇〇~3〇%, Sr〇0~30%, BaO 〇~30%, preferably in mass%, containing si〇2 50~70%, Al2〇3 10~20%, B2〇3 3~15%, MgO 〇~15°/〇,

An aluminosilicate having a composition of CaO 0 to 15%, SrO 0 to 15%, and Ba〇 〇 15% is a salt-free glass composition. In the composition range, it is desirable to obtain a glass having a strain point of 630 to 655 ° C, for example, as long as it is suitably in mass%, containing SiO 50 50 to 65%, Al 2 〇 3 10 to 20%, B 2 〇 3 5~ 15%, Mg〇0~5%, CaO 0~10°/. , SrO 0~10% ' BaO 0~15%, preferably in mass %, containing SiO 50 50~65%, A1203 12~17%, B2〇3

5 to 13. /. The raw material may be selected in such a manner that the composition of the glass is in the range of MgO 0 to 2%, CaO 3 to 9%, SrO 4 to 10%, and BaO 0 to 10%. Further, it is desirable to obtain a glass having a strain point of 655 to 680 ° C, for example, as long as it is suitably contained in mass%, containing SiO 50 50 to 65%, Al 2 〇 3 10 to 20%, b 203 5 to 15%, MgO 0 ~5%, CaO 0~10%, Sr〇〇~10%, Ba〇0~5%, preferably in mass%, containing SiO 50 50~65%, A1203 14~19%, B2〇3 7~ 15%, MgO 0~2%, CaO 3~10〇/〇, SrO 0~5%, BaO 0~2% of the composition of the glass, select the raw material is 118502.doc 200825033 can ::›: Zhou Hezhi's original glass is supplied to the glass melting device for melting. The degree of melting can be adjusted according to the type of glass „ ^ , ρ ρ , for example, in the case of the above-mentioned glass, as long as it is measured to the extent of 165 The temperature makes the basin cool. Further, what is referred to in the present invention includes clarification, and (iv) various steps. r

Next, the (four) glass is formed into a plate glass shape and allowed to cool. In the adjustment of the heat shrinkage characteristics of the glass substrate, it is important to manage the temperature history of the cold region in which the formed sheet glass is cooled to room temperature. Specifically, the average cooling rate in the temperature range from the cold spot to 10 CTC is adjusted to 300 ° C / min or more. When the average cooling rate is adjusted to 3 〇〇 t > c / min or more, the absolute value of the heat shrinkage rate of the glass substrate is large, but the variation of the heat shrinkage rate due to the change of the manufacturing conditions is small. For example, even if the cooling rate in the cold temperature region is changed to 60 t/min, the amount of change in the heat shrinkage rate can be suppressed to 3 ppm or less, especially below 2 ppm, especially at! Below ppm. As a result, it is difficult to cause an error in the heat shrinkage ratio between the glass substrates. Further, in order to prevent the glass from being uncomfortable, or the excess load is applied to the formed body, the upper limit of the average cooling rate is preferably 1 Torr. 〇 / min below. For example, in the case of producing a glass having a strain point of 630 to 655 t, in order to change the cooling rate to 60 ° C /min from the average cooling rate, a glass substrate having a thermal shrinkage change amount of 3 ppm or less can be obtained as long as The average cooling rate in the temperature range from Xu cold point to 100 ° C cooling temperature can be controlled at 350 ° C / min or more. Further, the glass substrate obtained by this condition has an absolute heat shrinkage ratio of about 60 ppm or more. In order to change the amount of heat shrinkage to 2 ppm or less, only 118502.doc -18- 200825033 should be used to control the average cooling rate to 410 ° C / min or more, so that it becomes i ppm or less, as long as the average cooling rate is controlled. At 5 1 〇 ° C / min or more. The absolute value of the heat shrinkage rate of the glass substrate obtained under these conditions was about 63 ppm or more and about 66 ppm or more. In order to manufacture a glass having a strain point of 655 to 680 ° C, in order to change the cooling rate to 60 ° C /min, a glass substrate having a thermal shrinkage change of 3 ppm or less can be obtained, as long as it is cooled by The average cooling rate in the temperature range of rc cooling is controlled to be 300 ° C / min or more. Further, the absolute value of the thermal shrinkage of the glass substrate obtained under this condition is about 5 〇 ppm or more. The amount of change is 2 ppm or less, and the average cooling rate may be controlled to 360 C/min or more. To achieve a value of {ppm or less, the average cooling rate may be controlled to 420 ° C / min or more. The absolute value of the heat thinning rate of the glass substrate is about 53 ppm or more and about 55 ppm or more. As one of the most effective methods for increasing the average cooling rate, there is a method of increasing the speed of the sheet glass. The faster the speed is increased, the greater the absolute value of the heat shrinkage rate of (4), the more the error of the heat shrinkage rate caused by the variation of the speed of the pull plate

Zoom out. In order to increase the speed of the drawing plate, it is only necessary to increase the rotational speed of the stretch-formed glass. Further, when the cooling zone (the aftercooling furnace) in the forming step is much shorter than the float method, the average cooling rate in this temperature region can be easily increased. Further, when the overflow down-draw method of one of the following pull methods is formed, a glass substrate having a superior surface quality can be obtained, and the advantage of the step (4) can be obtained. Specifically, 'Xu cold points to (10). The temperature of the C-cooling temperature range is preferably 150 cm/min or more, 270 cm/min to H8502.doc 19 200825033, more preferably 320 cm/min or more, especially 400 cm/min or more. Further, although there is no particular upper limit for the pulling speed, it is preferable to use the load of the forming device at 800 cm/min or less. Moreover, in the continuous manufacturing step, the faster the pulling speed is, the more difficult it is to keep the speed constant. As a result, the greater the error of the pulling speed (= cooling rate), the more likely the error in the heat shrinkage rate is caused. The situation caused by the error of the speed of the pull plate cannot be ignored, for example, as long as the pull is monitored

The speed of the plate is controlled, and the speed of the tension roller and the flow rate of the glass are controlled to keep the speed of the plate constant. In the case of the following drawing method, since the plate is pulled in the vertical direction, it is affected by the convection. Therefore, it is easier to change than the cold portion speed of the float which is pulled in the horizontal direction. Therefore, when the cooling rate of the glass is increased, the stability of the heat shrinkage rate which has been difficult to achieve in the past can be achieved. That is,

In the case of the down-draw method, it is advantageous to use the method of the present invention. In addition, in the case of manufacturing large-sized gull 33⁄4 ±τζ / sloping substrate, for example, on the short side of 1500 mm or more, especially on the short side of the substrate, the error of thermal shrinkage between the substrates The requirement f is more strict. That is to say, in the case where the amount of change in the heat shrinkage rate is the same, the error of the dimensional change caused by the heat shrinkage of the large-sized glass substrate is smaller than that of the small substrate. Therefore, if the cooling rate of the glass can be sufficiently increased, even if it is large, the 1 & wrench can reduce the error of dimensional change. Therefore, in the case of manufacturing a large slope from the substrate, it can be said that the advantage of applying the method of the present invention is large. Thereafter, the plate-shaped broken glass is cut into ^ ^ ^ Λ, and the size of the special shape is broken, and then necessary treatment such as end surface treatment and washing is performed. 118502.doc •20- 200825033 In this way, a glass substrate with a large heat shrinkage ratio can be obtained. EXAMPLES Hereinafter, the present invention will be described based on examples. First, the glass raw material is adjusted into a main component in terms of mass%, and contains SiO 2 60 / 〇 Al 2 〇 3 15% λ Β 2 〇 3 10% > CaO 5% ^ SrO 5% ^ Ba 〇 2 /. The composition, after mixing, is Μ% at the highest temperature in the continuous melting furnace. . Make it dazzling (five) #用〉益流下纟法开开” The molten glass is formed into a plate shape at various pulling speeds. Thereafter, the sheet glass was cut to obtain an alkali-free glass substrate of 1 500 x 1 800 x 065 mm. The glass substrate has a strain point of 650 ° C, a cold point of 705 t: and a liquid viscosity of 1 〇 5.G · s. Further, the strain point and the cold point were confirmed by the fiber drawing method according to ASTM C336_7. The glass was pulverized and passed through a standard sieve 3 筛 sieve (mesh opening 500 μιη), and the glass powder remaining in the 5 筛 sieve (mesh opening 3 〇〇 μηη) was placed in a platinum boat at a temperature slope. The temperature of the precipitation of the crystal, that is, the liquidus temperature, was measured in the furnace for 24 hours, and the liquidus viscosity was determined from the high temperature viscosity corresponding to the temperature. Further, the high temperature viscosity was measured by a platinum ball pull-up method. Fig. 3 is a view showing the glass substrate obtained at a sheet speed of 1 〇〇, 200 cm/min, 270 cm/min, 32 〇cm/min, 4 〇〇 (10) minutes and 500 cm/min. The heat history of forming. From Fig. 3, it can be seen that the faster the speed of the pull plate, the faster the average cooling rate. Further, the heat history at the time of glass forming is determined by the distribution of the orchestration direction and the speed of the pull plate as shown by the thermocouples provided in the cold zone. The speed of the drawing plate refers to the speed at which the formed glass substrate passes through the cold zone in the case of 118502.doc -21 - 200825033. In the present embodiment, the measuring roller is brought into contact with the middle portion of the cold zone (equivalent It is measured at the position where the cold point is -50 ° C). The term "cold zone" means a zone corresponding to the temperature range from the cold spot to the temperature drop of 1 oo °c in the central portion in the plate width direction. In this embodiment, it means calculating the center of the glass plate width direction. The portion becomes an area of 705 ° C to 605 ° C. In addition, the average cooling rate is a speed obtained by dividing the temperature in the cold region (= 100 ° C) by the time when the central portion in the width direction of the glass passes through the cold region. Next, using a glass substrate formed by various pull plate speeds, the temperature table shown in Fig. 1 was obtained (heating at a normal temperature of 10 ° C /min, maintaining the temperature at 450 ° C for 10 hours, at 10 ° C /minus speed reduction) The average cooling rate and the absolute value of the heat shrinkage rate during heat treatment are shown in Table 1. Further, the relationship between the average cooling rate and the absolute value of the heat shrinkage rate at this time is as shown in Fig. 2 . [Table 1] Plate speed (cm/min) Cooling rate ° (: / min 705-605 〇 C Heat shrinkage (ppm) A (ppm) 100 130 45 6 ppm 150 190 51 200 260 55 5 ppm 250 320 59 270 350 60 4 ppm 320 410 63 320 410 63 3 ppm 370 470 65 400 510 66 2 ppm 460 670 67 500 640 67 1 ppm 550 710 67 118502.doc -22- 200825033 As can be seen from the table, with the average cooling rate ( = increase in the speed of the pull plate, the absolute value of the heat shrinkage rate will increase, but at the same time, the amount of change in the heat shrinkage rate of the change in the cooling rate will become smaller. Moreover, the absolute value of the heat shrinkage rate is obtained by the following method First, the glass plate sample was cut out from the central portion of the obtained glass substrate, as shown in Fig. ♦), the specific disposal person of the π 纟 glass plate 1 was linearly marked, and the glass plate 1 was dried. Split vertically into two glass sheets i ^ b. However, only one of the glass sheets U is heat treated with the thermometer shown in Fig. 1 (heating at a normal temperature by a 10 C" knife speed to maintain the temperature of 45 〇. 〇 keeps the hour, yak at the speed of the c-knife Λ). Thereafter, as shown in FIG. 4(b), the glass sheet la and the untreated glass sheet (4) which are subjected to the heat== are arranged and the two pieces are fixed by the adhesive π (not shown), and then the The shift of the mark 2 was measured by a microscope and was determined by the following formula 1. Further, 1 in the formula 1 indicates that the distances between the marks 'AL丨' and AL2 indicate the positional shift amount of the mark. [Number 1] i xl° _)...·Form 1 [Simple description of the diagram]. An explanatory diagram of a thermometer for determining the absolute value of the heat shrinkage rate is shown. Fig. 2 is a graph showing the relationship between the average cooling rate and the absolute value of the heat shrinkage rate. Figure 3 is a graph showing the thermal history of the glass in the cooling step of Figure 0 during molding. Figure 4 (a) (b) shows the method for determining the absolute value of the heat shrinkage rate 118502.doc -23 - 200825033 Figure [Main components Explanation of Symbols: The glass plate sample a for obtaining the absolute value of the heat shrinkage rate is obtained. The half piece of the glass plate sample (the glass plate subjected to the heat treatment) for obtaining the absolute value of the heat shrinkage rate is determined. Half of the plate sample (glass plate without heat treatment) mark 118502.doc -24-

Claims (1)

200825033 X. Patent application scope: An alkali-free glass substrate characterized in that it is heated at a temperature of i (rc/* at a normal temperature to maintain a temperature of 450. (: the absolute value of the heat shrinkage rate when the temperature is lowered by 1 (rc/*) for 1 hour. 50 ppm or more. For example, the alkali-free glass substrate of item 1 has a strain point of 63 〇 to 655 〇, and the heat recovery rate is an absolute value of 6 〇 ppm or more. The glass substrate, wherein the strain point is 655 to 68 〇. 〇, and the absolute heat yield is 5 〇 ppm or more. The alkali-free glass substrate of any one of items 1 to 3, wherein the liquid viscosity is 1无4·5 Pa · s or more. 5. The alkali-free glass substrate according to any one of items 1 to 4, which is formed by an overflow down-draw method. 6 · As shown in the items 1 to 5 Any one of the alkali-free glass substrates, wherein the mass% is 50% to 70%, Al2〇3 1 to 20%, B203 〇 15%, MgO 〇 〇〇 3 〇〇 / 0, Ca 以～30%, SrO 0 to 30%, and BaO 0 to 30%. 7_— A method for producing an alkali-free glass substrate, which is characterized in that the glass raw material is melted and molded to produce an alkali-free glass substrate. In the cooling process during forming, the average cooling rate in the temperature range from the cold point to 1 〇〇. 〇 cooling is 30 (rc / min or more. 8. The alkali-free glass of claim 7 In the method for producing a substrate, in the method of melting and molding a glass raw material to produce an alkali-free glass substrate having a strain point of 630 to 655 ° C, the average cooling rate is 35 〇 t: /min or more. The method for producing an alkali-free glass substrate according to Item 7, wherein in the method of melting and forming a raw material of glass 118502.doc 200825033 to produce an alkali-free glass substrate having a strain point of 655 to 68 (rc, the average cooling rate is 300 ° C / The method for producing an alkali-free glass substrate according to any one of items 7 to 9, which is to produce an alkali-free glass substrate having a liquidus viscosity of 1 〇 4.5 Pa·s or more. The method for producing an alkali-free glass substrate according to any one of the items 7 to 1 which is formed by an overflow down-draw method. 12. The alkali-free glass substrate according to any one of claims Manufacturing method in which the production has a mass%, containing Si〇2 5 ~70%, Al2〇3 1~20%, B2〇3 〇~15%, Mg〇〇~30%, CaO 0~30%, SrO 0~3 0%, BaO 〇~3 0% Alkali glass substrate. 13 - A method for producing a non-inspective glass substrate, which is a method for melting and forming a glass raw material to produce an alkali-free glass substrate, and in the cooling process during forming, is in a cold point to 1 〇〇 〇 〇 〇 〇 〇 之 之 之 之 之 之 之 之 之 之 之 之 温度 温度 温度 温度 平均 平均 平均The method for producing an alkali-free glass substrate according to claim 13, which is to produce an alkali-free glass substrate having a liquidus viscosity of 104·5 Pa·s or more. 15. The method of producing an alkali-free glass substrate according to claim 13 or 14, which is formed by an overflow down-draw method. The method for producing an alkali-free glass substrate according to any one of claims 13 to 15, wherein the production has a mass percentage of 50% to 70%, Al2〇3 1 to 20%, and B2〇3 0 An alkali-free glass substrate having a composition of ~15%, MgO 0 to 30%, CaO 〇 30%, SrO 0 to 3 0%, and BaO 0 to 3 0%. An alkali-free glass substrate, which is produced by the method of any one of claims 7 to 16. 118502.doc