WO2016152932A1

WO2016152932A1 - Method for manufacturing glass substrate

Info

Publication number: WO2016152932A1
Application number: PCT/JP2016/059251
Authority: WO
Inventors: 修猪飼; 小林　健二
Original assignee: ＡｖａｎＳｔｒａｔｅ株式会社
Priority date: 2015-03-24
Filing date: 2016-03-23
Publication date: 2016-09-29
Also published as: CN106795042B; KR20170052523A; JP6368364B2; TWI613041B; CN106795042A; KR101909797B1; JPWO2016152932A1; TW201639660A

Abstract

The purpose of the present invention is to provide a method for manufacturing a glass substrate which is capable of efficiently improving the cleanliness of the surfaces of the glass substrate. This method for manufacturing a glass substrate comprises: a cutting step of cutting the glass substrate; an edge machining step of machining cut edges which are cut surfaces of the glass substrate cut in the cutting step; and a surface treatment step of treating the main surface of the glass substrate cut in the cutting step. In the edge machining step, the shape of the cut edges is machined while a grinding fluid is fed to the cut edges. In the surface treatment step, an alkaline solution having a pH of less than 10 is applied onto the main surface, and the surface treatment step is performed at the same time as the edge machining step.

Description

Manufacturing method of glass substrate

The present invention relates to a method for manufacturing a glass substrate.

Glass substrates used for flat panel displays (FPD) such as liquid crystal displays and plasma displays are required to have high flatness on the surface. Usually, such a glass substrate is manufactured by the overflow down draw method. In the overflow downdraw method, as described in Patent Document 1 (US Pat. No. 3,338,696), molten glass that has been poured into the groove on the upper surface of the molded body and overflowed from the groove is A glass ribbon is formed by flowing down along both side surfaces and joining at the lower end of the formed body. The formed glass ribbon is gradually cooled while being pulled downward. The cooled glass ribbon is cut into a predetermined dimension to obtain a glass substrate.

Thereafter, end face processing for grinding and polishing the cut surface of the glass substrate is performed. In end face processing of a glass substrate, cullet, which is a minute piece of glass, may be generated from the end face and adhere to the surface of the glass substrate. Since the cullet attached to the surface of the glass substrate causes disconnection and peeling of the TFT wiring formed on the surface, it is preferably removed from the surface as much as possible. In Patent Document 2 (Japanese Patent Application Laid-Open No. 2008-87135), cullet generated during end face processing adheres to the glass substrate surface by spraying water in the form of a curtain from the center of the surface of the glass substrate toward the end face side. A method of suppressing this is disclosed.

However, in this method, the adhesion of cullet to the surface in the vicinity of the end face is suppressed, but the adhesion of cullet to the center of the surface may not be sufficiently suppressed. Moreover, since water is ejected toward the surface of the glass substrate, the end surface of the glass substrate may vibrate during end surface processing, and the accuracy of end surface processing may be reduced.

In recent years, glass substrates have become larger and thinner, and large glass substrates having a side dimension exceeding 2000 mm have been manufactured as glass substrates for high-definition displays. Since the TFT wiring electrode pattern that is finer and denser than the conventional pattern is formed on the surface of the glass substrate for high-definition displays, it is a microscopic level that has not been regarded as a problem with conventional glass substrates for displays. Even if a cullet is attached to the surface, there is a possibility that a problem occurs in the quality of the product. Further, in the manufacturing process of a large glass substrate, it is necessary to process the end surface of the glass substrate at a high speed in order to improve productivity. Therefore, cullet is easily generated and scattered during the end surface processing. As described above, since the surface of a large glass substrate for high-definition displays is required to have high cleanliness, a method for efficiently removing cullet attached to the surface of the glass substrate in the glass substrate manufacturing process is required. ing.

Therefore, an object of the present invention is to provide a method for producing a glass substrate that can efficiently improve the cleanliness of the surface of the glass substrate.

The method for producing a glass substrate according to the present invention includes a cutting step for cutting a glass substrate, an end face processing step for processing a cut end surface that is a cut surface of the glass substrate cut in the cutting step, and a glass cut in the cutting step. A surface treatment process for treating the main surface of the substrate. In the end face processing step, the shape of the cut end face is processed while supplying a grinding liquid to the cut end face. In the surface treatment step, an alkaline liquid having a pH of less than 10 is applied to the main surface, and is performed simultaneously with the end face processing step.

In addition, the alkaline liquid agent preferably contains a surfactant.

Further, it is preferable that the grinding liquid is an alkaline liquid and the content of the surfactant is adjusted so as to have a surface tension of 30 mN / m to 50 mN / m at 20 ° C.

Moreover, it is preferable that the manufacturing method of a glass substrate further includes the washing | cleaning process of wash | cleaning a glass substrate after the surface treatment process using the washing | cleaning liquid different from an alkaline liquid agent.

The glass substrate is preferably aluminosilicate glass or alkali aluminosilicate glass containing SiO ₂ in an amount of 50 to 70% by mass and Al ₂ O ₃ in an amount of 10 to 25% by mass.

Further, the glass substrate is preferably manufactured by an overflow down draw method.

The glass substrate is preferably a display glass substrate having a pair of main surfaces, which are an element formation surface and a roughened surface. In this case, the roughened surface is preferably roughened by wet etching so that the arithmetic average roughness Ra becomes 0.3 nm to 0.7 nm.

The method for producing a glass substrate according to the present invention can efficiently improve the cleanliness of the surface of the glass substrate.

It is sectional drawing of the glass substrate which concerns on embodiment. It is a flowchart which shows the manufacturing method of the glass substrate which concerns on embodiment. It is sectional drawing of the glass substrate which has the cut end surface ground. It is a top view by the side of the element formation surface of a glass substrate. It is a graph showing the pH dependency of the zeta potential of SiO ₂ and Al ₂ O _3.

(1) Outline of glass substrate manufacturing method A glass substrate manufacturing method according to an embodiment of the present invention will be described with reference to the drawings. The glass substrate 10 manufactured by the manufacturing method of the glass substrate of this embodiment is used for manufacture of flat panel displays (FPD), such as a liquid crystal display, a plasma display, and an organic EL display. The glass substrate 10 is also used for manufacturing a solar cell panel. The glass substrate 10 has, for example, a thickness of 0.1 mm to 1.1 mm and a size of 360 mm to 3000 mm and 460 mm to 3200 mm.

FIG. 1 is a cross-sectional view of the glass substrate 10. The glass substrate 10 has an element forming surface 12 that is one main surface and a roughened surface 14 that is the other main surface. The element formation surface 12 is a surface on which a semiconductor element such as a TFT is formed in the FPD manufacturing process. The element formation surface 12 is a surface on which, for example, a low-temperature polysilicon semiconductor or an oxide semiconductor is formed, and a low-temperature polysilicon thin film, an ITO (Indium Thin Oxide) thin film, and a multi-layer thin film made of a color filter or the like are formed. It is the surface to be done. In a display TFT panel for high definition and high resolution, the thickness of the gate insulating film of the TFT is less than 100 nm. For example, development and manufacture of a TFT panel in which the thickness of the gate insulating film is less than 50 nm has been promoted. In such a TFT panel, not only the gate insulating film but also the thickness of each layer forming the semiconductor element is thin. Therefore, the element formation surface 12 is an extremely smooth surface having Ra (arithmetic mean roughness: JIS B 0601: 2001) of 0.2 nm or less. The glass substrate 10 on which the TFT is formed on the element formation surface 12 preferably has a circuit in which the minimum line width of the wiring is less than 4 μm and the thickness of the gate insulating film is less than 100 nm. The material of the electrode used for the TFT panel is a Cu-based material such as Ti—Cu and Mo—Cu.

The roughened surface 14 is a surface on which minute irregularities are formed by an etching process in the manufacturing process of the glass substrate 10. The roughened surface 14 is roughened so that the arithmetic average roughness Ra is 0.3 nm to 0.7 nm. The etching process is, for example, a dry etching process or a wet etching process. In addition, as long as the roughened surface 14 can form a desired surface state, unevenness | corrugation may be formed by surface treatments other than an etching process. For example, the roughened surface 14 may have irregularities formed by physical polishing such as tape polishing, brush polishing, pad polishing, abrasive polishing, and CMP (Chemical Mechanical Polishing).

The glass used for the glass substrate 10 is an aluminosilicate glass or an alkali aluminosilicate glass having the following composition.

(A) SiO ₂ : 50% by mass to 70% by mass,
(B) Al ₂ O ₃ : 10% by mass to 25% by mass,
(C) B ₂ O ₃ : 0% by mass to 18% by mass,
(D) MgO: 0% by mass to 10% by mass,
(E) CaO: 0% by mass to 20% by mass,
(F) SrO: 0% by mass to 20% by mass,
(G) BaO: 0% by mass to 10% by mass,
(H) RO: 5% by mass to 20% by mass (R is at least one selected from Mg, Ca, Sr and Ba),
(I) R ′ ₂ O: 0% by mass to 2.0% by mass (R ′ is at least one selected from Li, Na and K),
(J) At least one metal oxide selected from SnO ₂ , Fe ₂ O ₃ and CeO ₂ .

It should be noted that the glass having the above composition is allowed to contain other trace components in the range of less than 0.1% by mass.

Next, the manufacturing process of the glass substrate 10 for FPD using the overflow downdraw method will be described. FIG. 2 is an example of a flowchart showing a manufacturing process of the glass substrate 10. The manufacturing process of the glass substrate 10 mainly includes a forming process (step S1), a slow cooling process (step 2), a plate-making process (step S3), a cutting process (step S4), and an end face processing process (step S5). ), A surface treatment process (step S6), a roughening process (step S7), a cleaning process (step S8), an inspection process (step S9), and a packing process (step S10).

In the forming step S1, a sheet-like glass ribbon is formed from a molten glass obtained by heating a glass raw material by an overflow down draw method. Specifically, the glass ribbon overflowing from the upper part of the molding cell flows downward along both side surfaces of the molding cell and joins at the lower end of the molding cell, whereby the glass ribbon is continuously molded. The molten glass is cooled to a temperature suitable for molding by the overflow downdraw method, for example, 1200 ° C. before flowing into the molding step S1.

In the slow cooling step S2, the glass ribbon molded in the molding step S1 is gradually cooled to a glass annealing point or lower while the temperature is controlled so that distortion and warpage do not occur. In the slow cooling step S2, the glass ribbon is cooled while being conveyed downward.

In the plate-drawing step S3, the glass ribbon slowly cooled in the slow-cooling step S2 is cut for each predetermined length, and the end region is further cut to obtain a base plate glass. The end regions are formed at both ends in the width direction of the glass ribbon and are thicker than the central region in the width direction of the glass ribbon. The base glass obtained by the plate-drawing step S3 is alternately laminated together with the interleaving paper, and is conveyed to the cutting step S4.

In the cutting step S4, the base glass obtained in the plate-drawing step S3 is cut into a predetermined size to obtain a glass substrate 10 having a product size. The base glass is cut using, for example, a laser.

In the end face processing step S5, the end face of the glass substrate 10 obtained in the cutting step S4 is processed. The end surface processed in the end surface processing step S5 is the cut end surface 16 of the glass substrate 10 cut in the cutting step S4. The end face processing step S5 mainly includes a grinding step and a polishing step. The grinding process is a process of grinding the cut end face 16 while supplying the grinding liquid to the cut end face 16 to process the cut end face 16 into an R shape. FIG. 3 is a cross-sectional view of the glass substrate 10 having the cut end face 16 ground in the grinding process. The polishing step is a step of polishing the cut end surface 16 so that the arithmetic average roughness Ra of the cut end surface 16 ground in the grinding step is 0.1 μm or less.

In the surface treatment step S6, the element formation surface 12 is subjected to a surface treatment by applying an alkaline liquid having a pH of less than 10 to the element formation surface 12 of the glass substrate 10 obtained in the cutting step S4. The surface treatment step S6 is performed simultaneously with the end face processing step S5. Specifically, the step of applying the alkaline liquid agent to the element forming surface 12 in the surface treatment step S6 and the grinding step of grinding the cut end surface 16 using the grinding liquid in the end surface processing step S5 are simultaneously performed. In the surface treatment step S6, the alkaline liquid applied to the element forming surface 12 is removed after the grinding step of the end face processing step S5 is completed.

In the roughening step S7, a surface treatment is performed to increase the surface roughness of the roughened surface 14 of the glass substrate 10 that has undergone the end face processing step S5 and the surface treatment step S6. The surface treatment performed in the roughening step S7 is, for example, a wet etching process.

In the cleaning step S8, the glass substrate 10 that has undergone the roughening step S7 is cleaned with a cleaning liquid. The cleaning liquid is a liquid agent different from the alkaline liquid agent used in the surface treatment step S6. In addition, it is preferable not to dry the glass substrate 10 which became wet with the grinding liquid adhering to the main surface of the glass substrate 10 in the end face processing step S5 until the cleaning step S8 is completed. This is because if it is dried before the cleaning step S8 is completed, components contained in the grinding liquid may precipitate and adhere to the main surface of the glass substrate 10.

In the inspection step S9, the glass substrate 10 cleaned in the cleaning step S8 is inspected. Specifically, the main surface of the glass substrate 10 is optically measured to detect a defect in the glass substrate 10. The defects of the glass substrate 10 include, for example, striae formed on the main surface of the glass substrate 10, scratches and cracks existing on the main surface of the glass substrate 10, foreign matters attached to the main surface of the glass substrate 10, and These are minute bubbles or the like existing inside the glass substrate 10.

In the packing step S10, the glass substrate 10 that has passed the inspection in the inspection step S9 is alternately stacked on a pallet and packed with a slip sheet for protecting the glass substrate 10. The packed glass substrate 10 is shipped to an FPD manufacturer or the like. The FPD manufacturer manufactures FPDs by forming semiconductor elements such as TFTs on the element forming surface 12 of the glass substrate 10.

(2) Details of Surface Treatment Step The surface treatment of the element forming surface 12 performed in the surface treatment step S6 will be described. In the surface treatment step S <b> 6, an alkaline liquid agent is applied to the element formation surface 12. The alkaline solution is a solution having a pH of less than 10 and a solution containing a surfactant. The pH of the alkaline solution is preferably 8-9. An alkaline liquid agent is ammonia water, for example. The alkaline solution may be an amine solution such as triethanolamine. The surfactant is, for example, a nonionic surfactant.

FIG. 4 is a plan view of the glass substrate 10 on the element forming surface 12 side. In the surface treatment step S6, an alkaline liquid agent is applied to at least the central region 12a of the element forming surface 12. As shown in FIG. 4, the central region 12 a is a quadrangular region excluding an end portion around the element forming surface 12. The distance L between the end of the central region 12a and the end of the element formation surface 12 is 2 mm to 20 mm.

The alkaline liquid applied to the element forming surface 12 is removed after the grinding process of the end face processing step S5 is completed. The alkaline liquid agent adhering to the element forming surface 12 may be removed from the element forming surface 12 by spraying a fluid onto the element forming surface 12. For example, the alkaline liquid agent may be removed from the element forming surface 12 by spraying pure water from the nozzle toward the element forming surface 12 at a predetermined pressure. In addition, the alkaline liquid agent may be removed from the element forming surface 12 by cleaning the element forming surface 12 with a brush. In any case, it is preferable to prevent the element forming surface 12 from drying by removing the alkaline liquid agent from the element forming surface 12 and then showering the element forming surface 12 with pure water. The alkaline liquid agent removed from the element forming surface 12 is collected. The recovered alkaline solution may be reused after passing through a filter and removing foreign substances contained in the alkaline solution.

(3) Details of end face processing step The grinding step of the cut end face 16 performed in the end face processing step S5 will be described. In the grinding process of the end face processing step S5, the cylindrical grinding wheel is rotated, and the side peripheral surface of the grinding wheel is brought into contact with the cut end face 16 of the glass substrate 10. Thereby, as FIG. 3 shows, a pair of corner | angular part of the cutting end surface 16 is ground so that it may have R shape. The machining allowance of the cut end face 16 in the grinding process is preferably 30 μm to 150 μm.

The grinding wheel is molded with a metal bond grindstone. A metal bond grindstone is a grindstone manufactured by fixing multiple types of metal powders or alloy powders with an iron-based or copper-based binder and sintering them, and then fixing the abrasive grains on the surface of the sintered body. It is. The abrasive grains are fine grains such as diamond, aluminum oxide and silicon carbide. The grain size of the abrasive grains of the grinding wheel is preferably # 500 to # 600. The grinding wheel is driven to rotate around the rotation axis by an electric motor.

In the grinding process, the cutting end face 16 is ground by the grinding wheel while supplying the grinding liquid to the cutting end face 16 of the glass substrate 10. Frictional heat is generated in a region where the cut end surface 16 of the glass substrate 10 and the rotating grinding wheel are in contact with each other. The frictional heat causes the glass substrate 10 to be altered by heating the cut end face 16. The grinding fluid functions as a coolant that suppresses heating of the cut end face 16.

In the end face processing step S5, the same liquid as the alkaline liquid used in the surface treatment step S6 is used as the grinding liquid. When the grinding fluid is alkaline, the grinding fluid easily penetrates into the gap between the cut end face 16 and the grinding wheel, so that the cooling effect of the grinding fluid is improved. Further, when the grinding fluid contains a surfactant, the surface tension of the grinding fluid is lowered, so that the permeability of the grinding fluid is increased and the cooling effect of the grinding fluid is further improved. From the viewpoint of improving the permeability of the grinding fluid, the content of the surfactant is preferably adjusted so that the grinding fluid has a surface tension of 30 mN / m to 50 mN / m at 20 ° C. Moreover, it is preferable that the content of the surfactant is adjusted so that the grinding liquid has a surface tension of 30 mN / m or more and less than 48 mN / m at 20 ° C.

(4) Features In the process of manufacturing an FPD from the glass substrate 10, on the element forming surface 12 of the glass substrate 10, a semiconductor element such as a TFT, specifically, a multi-layer thin film composed of a polysilicon thin film, an ITO thin film, etc. Is formed. When a wiring electrode of a semiconductor element is formed on the element formation surface 12, if foreign matter adheres to the element formation surface 12, the wiring electrode formed on the element formation surface 12 may be disconnected or peeled off. Therefore, in the manufacturing process of the glass substrate 10, it is preferable to remove foreign substances from the element forming surface 12 as much as possible. A typical example of the foreign material is cullet, which is a small piece of glass. The cullet is generated mainly from the cut surface that becomes the cut end surface 16 of the glass substrate 10 when the glass ribbon is cut in the plate-drawing step S3 and the cutting step S4. A part of the cullet generated from the cut end face 16 adheres to the element forming surface 12 of the glass substrate 10. As the height of the cullet adhering to the element forming surface 12 (maximum distance from the element forming surface 12) is higher, the formation defect of the wiring electrode of the semiconductor element is more likely to occur. Examples of other foreign substances include dust, dust, and organic substances present in the atmosphere.

In the method for manufacturing a glass substrate according to the present embodiment, an alkaline liquid agent is applied to the element forming surface 12 in the surface treatment step S6 in order to remove foreign matters attached to the element forming surface 12 of the glass substrate 10. The pH of the alkaline solution is less than 10. By applying the alkaline liquid agent to the element forming surface 12, the cullet attached to the element forming surface 12 is peeled off from the element forming surface 12 and removed. Next, a mechanism for removing the cullet will be described.

The glass substrate 10 is made of aluminosilicate glass or alkali aluminosilicate glass. The main components of the glass composition of the glass substrate 10 are SiO ₂ and Al ₂ O ₃ . Therefore, the cullet generated from the cut end face 16 of the glass substrate 10 is mainly composed of SiO ₂ and Al ₂ O ₃ . In particular, the proportion of SiO _{2 in} the glass composition of cullet is large. When the element forming surface 12 and the cullet are both charged and the sign of the charge on the element forming surface 12 is opposite to the sign of the cullet charge, the cullet is formed on the element forming surface by repulsion due to electromagnetic force. 12 easily adheres.

FIG. 5 is a graph showing the pH dependence of the zeta potential (electrokinetic potential) of SiO ₂ and Al ₂ O ₃ which are the main components of cullet. In FIG. 5, the vertical axis represents zeta potential (unit: mV), and the horizontal axis represents pH. As shown in FIG. 5, the zeta potential of SiO ₂ and Al ₂ O ₃ decreases with increasing pH. In particular, the zeta potential of SiO ₂ greatly decreases at pH 5 to 6, and becomes a substantially constant negative value (−40 mV) above pH 6.

Therefore, by applying an alkaline solution to the element formation surface 12, SiO ₂ present in the element forming surface 12, and, since the zeta potential of SiO ₂ present in the cullet is a negative value, the element formation surface 12 and cullet The surface of is negatively charged. Therefore, the cullet is easily peeled off from the element forming surface 12 due to the repulsive force of the electromagnetic force acting on the charges having the same sign.

Note that the zeta potential of SiO ₂ becomes substantially constant at pH 6 or higher. However, when the alkaline liquid applied to the element forming surface 12 is further used as the grinding liquid used in the end surface processing step S5, the grinding liquid is preferably alkaline from the viewpoint of the permeability of the grinding liquid. Further, from the viewpoint of suppressing the quality change of the glass at the cut end face 16, it is preferable that the grinding liquid is not strongly alkaline. Therefore, the pH of the grinding fluid is preferably less than 10 and more preferably 8-9. In addition, it is preferable that the liquid agent apply | coated to the element formation surface 12 is also alkaline.

Further, as shown in FIG. 5, the zeta potential of Al ₂ O ₃ which is one of the main components of cullet becomes a negative value at pH 8 or higher. Therefore, in order to peel the cullet mainly composed of Al ₂ O ₃ from the element forming surface 12, the pH of the alkaline liquid applied to the element forming surface 12 is preferably 8-9.

Moreover, the alkaline solution contains a surfactant. The surfactant has an effect of separating and removing foreign matters other than cullet such as dust, dust and organic matter adhering to the element forming surface 12 from the element forming surface 12.

Further, the alkaline liquid applied to the element forming surface 12 is removed by a brush or the like after the end face processing step S5 and the surface treatment step S6 are completed. The cleaning liquid used for cleaning the glass substrate 10 in the cleaning step S8 is a liquid agent different from the alkaline liquid agent used in the surface treatment step S6. Therefore, in order to prevent the influence on the post-process, the alkaline liquid applied to the element formation surface 12 is removed from the element formation surface 12 as much as possible after the end face processing step S5 and before the start of the post-process. It is preferable to keep it. Further, in the subsequent roughening step S7, when the roughened surface 14, which is the main surface opposite to the element forming surface 12, is wet-etched using an acidic liquid agent, it adheres to the roughened surface 14. The alkaline liquid agent is preferably removed with pure water.

Therefore, the glass substrate manufacturing method according to the present embodiment can efficiently remove the cullet adhering to the element forming surface 12 by applying an alkaline liquid agent to the element forming surface 12. Therefore, in the process of manufacturing the FPD from the glass substrate 10, the occurrence of defects such as breakage and disconnection of the Cu-based wiring electrode of the semiconductor element formed on the element forming surface 12 is suppressed.

In recent years, glass substrates have become larger and thinner, and large glass substrates having a side dimension exceeding 2000 mm have been manufactured as glass substrates for high-definition displays. Since wiring electrodes with finer and higher density than the conventional wiring electrodes are formed on the surface of a glass substrate for high-definition displays, there is a small cullet at a level that was not regarded as a problem with conventional glass substrates for displays. Even if it adheres to the surface, there may be a problem in the quality of the product. Moreover, in the manufacturing process of a large glass substrate, it is necessary to process the end surface of the glass substrate at a high speed in order to improve productivity, so that cullet is likely to occur during the end surface processing.

In the manufacturing method of the glass substrate of this embodiment, even if the glass substrate 10 is large sized by the process of apply | coating an alkaline liquid agent to the element formation surface 12, adhesion of the cullet to the element formation surface 12 can be suppressed. Even when adhering, cullet can be efficiently removed. Further, negatively charging the element formation surface 12 and the cullet suppresses adhesion of the cullet to the element formation surface 12, and reduces the amount of cullet adhesion to the element formation surface 12 even with a small cullet. it can. Even when the cullet adheres to the element forming surface 12, the cullet can be removed in the cleaning step S8 in a later step. Therefore, the glass substrate manufacturing method of the present embodiment can efficiently remove minute cullet and glass particles at a level that has not been regarded as a problem in the conventional display glass substrate from the element forming surface 12. Furthermore, in the surface treatment step S6, by using an alkaline liquid agent containing a surfactant, organic substances attached to the element formation surface 12 can also be removed.

(5) Modification (5-1) Modification A
In the surface treatment step S <b> 6 of the present embodiment, an alkaline liquid agent is applied to the element formation surface 12 of the glass substrate 10. However, in the surface treatment step S <b> 6, an alkaline liquid agent may be applied to the roughened surface 14 of the glass substrate 10. By applying an alkaline solution to the roughened surface 14, the cullet attached to the roughened surface 14 is removed. In addition, in order to apply an alkaline solution to the element formation surface 12 and the roughened surface 14 of the glass substrate 10, the glass substrate 10 may be immersed in the alkaline solution.

In this modification, by applying an alkaline liquid agent to the roughened surface 14 which is the main surface opposite to the element forming surface 12, adhesion of cullet to the roughened surface 14 can be suppressed, and the roughening step S7. In FIG. 5, the occurrence of local etching unevenness on the roughened surface 14 can be suppressed.

Furthermore, by using an alkaline solution containing a surfactant, it is possible to remove organic substances adhering to the roughened surface 14, and to suppress the occurrence of etching unevenness caused by the organic substances acting as a mask. As a result, the arithmetic average roughness Ra of the central region of the roughened surface 14 can be set within a range of 0.4 nm to 0.6 nm. The central region of the roughened surface 14 is a region opposite to the central region 12 a of the element forming surface 12.

In addition, it is preferable that the roughening process of the roughened surface 14 is performed by the wet etching process using an acidic liquid agent. In the roughening treatment of the roughened surface 14, the temperature of the acidic liquid applied to the roughened surface 14 is such that the temperature of the glass substrate 10 rises and the element forming surface 12 of the glass substrate 10 does not dry. It is preferable that it is 50 degrees C or less, and it is more preferable that it is 30 degrees C or less.

(5-2) Modification B
The grinding process of the end face processing step S5 of the present embodiment is a process of grinding the cut end face 16 while supplying the grinding liquid to the cut end face 16 to process the cut end face 16 into an R shape. In the present embodiment, the same liquid as the alkaline liquid used in the surface treatment step S6 is used as the grinding liquid. However, the grinding fluid may be a liquid different from the alkaline liquid used in the surface treatment step S6. For example, pure water may be used as the grinding fluid.

10 Glass substrate 12 Element formation surface (main surface)
14 Roughened surface (main surface)
16 Cutting end face

U.S. Pat. No. 3,338,696 JP 2008-87135 A

Claims

A cutting step of cutting the glass substrate;
An end face processing step for processing a cut end face which is a cut face of the glass substrate cut in the cutting step;
A surface treatment step of treating a main surface of the glass substrate cut in the cutting step;
With
The end face processing step processes the shape of the cut end face while supplying a grinding liquid to the cut end face,
The surface treatment step is performed by applying an alkaline solution having a pH of less than 10 to the main surface, and simultaneously with the end face processing step.
A method for producing a glass substrate.
The alkaline solution includes a surfactant,
The manufacturing method of the glass substrate of Claim 1.
The grinding liquid is the alkaline liquid agent, and the content of the surfactant is adjusted so as to have a surface tension of 30 mN / m to 50 mN / m at 20 ° C.,
The manufacturing method of the glass substrate of Claim 2.
After the surface treatment step, further including a cleaning step of cleaning the glass substrate using a cleaning liquid different from the alkaline liquid agent.
The manufacturing method of the glass substrate of any one of Claim 1 to 3.
The glass substrate is an aluminosilicate glass or an alkali aluminosilicate glass containing 50% to 70% by mass of SiO 2 and 10% to 25% by mass of Al 2 O 3 .
The manufacturing method of the glass substrate of any one of Claim 1 to 4.
The glass substrate is manufactured by an overflow downdraw method,
The manufacturing method of the glass substrate of any one of Claim 1 to 5.
The glass substrate is a glass substrate for display having a pair of main surfaces, which are an element forming surface and a roughened surface,
The roughened surface is roughened by wet etching so that the arithmetic average roughness Ra is 0.3 nm to 0.7 nm.
The manufacturing method of the glass substrate of any one of Claim 1 to 6.