JP2014069998A - Glass substrate, and method for manufacturing glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass substrate in which the static build-up on a surface is effectively suppressed, and a method for manufacturing a glass substrate.SOLUTION: A glass substrate 10 is provided with an element formation surface 12a, and a roughened surface 12b. The element formation surface 12a is a surface where semiconductor elements are formed. The roughened surface 12b is a surface which lies opposite to the element formation surface 12a. The area incremental ratio of roughened surface 12b is at least 0.05%. The area incremental ratio is a value dS calculated by the equation dS=[(S-S)/S]×100(%), based on an actual area Sand a measurement area S. The actual area Sis a surface area calculated from three-dimensional data obtained by measuring a scan range of 1 μm×1 μm of the roughened surface 12b using an atomic force microscope, and is the surface area of the roughened surface 12b in the scan range. The measurement area Sis the area of the geometric shape in the scan range.

Description

  The present invention relates to a glass substrate and a method for producing a glass substrate.

  Conventionally, a glass substrate is used for manufacturing a flat panel display (FPD) such as a liquid crystal display device. In the FPD manufacturing process, in order to form a semiconductor element such as a TFT (Thin Film Transistor) on the surface of the glass substrate, the glass substrate is placed on a susceptor in a reaction vessel of a semiconductor manufacturing apparatus and subjected to a film formation process. . In order to form a plurality of types of thin films on a glass substrate, the film forming process is performed a plurality of times by a plurality of semiconductor manufacturing apparatuses. Each time a film forming process is performed, the glass substrate is removed from the susceptor. At this time, static electricity due to friction, that is, peeling electrification occurs between the metal surface of the susceptor on which the glass substrate is placed and the glass substrate surface, and the static electricity is accumulated on the glass substrate. Therefore, a glass substrate on which a plurality of film formation processes has been performed accumulates a large amount of static electricity. In particular, a glass substrate made of non-alkali glass used in a liquid crystal display device has a surface that is easily charged and static electricity is difficult to remove. And when generation | occurrence | production of peeling electrification is repeated, a glass substrate will adhere easily with the static electricity with respect to the metal surface of a susceptor. Therefore, when removing a glass substrate from a susceptor, an excessive force may be applied to the glass substrate and the glass substrate may be damaged. In addition, the voltage caused by static electricity accumulated due to peeling charging may destroy the semiconductor element formed on the glass substrate surface. Furthermore, there are cases where particles in the atmosphere are attracted to the surface of the glass substrate due to electrostatic charging of the glass substrate that occurs due to roller conveyance of the glass substrate.

  Under such circumstances, it has been proposed to manufacture a glass substrate in which surface charging is unlikely to occur in the FPD manufacturing process. For example, a glass substrate disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2005-255478) has a first surface on which electrode wires and various devices are formed, and a second surface opposite to the first surface. The second surface is a surface that has been physically polished or chemically treated and has a Ra (arithmetic mean roughness) of 0.3 nm to 10 nm. The glass substrate is prevented from being charged by the roughening treatment of the second surface.

  However, even when static electricity is accumulated on the glass substrate and the glass substrate surface is charged, if the static electricity is released from the glass substrate surface without electrostatic breakdown (ESD), the glass substrate surface Charging is suppressed.

  Here, when the movement of electric charge easily occurs in the glass substrate surface, the electric charge leaks from the glass substrate surface and the static electricity is easily released. Further, as described in Non-Patent Document 1 (Journal of the Electrostatic Society, Vol. 18, No. 4 (1994), pages 364 to 370), the greater the amount of moisture adsorbed on the surface of the glass substrate, the more the surface resistance of the glass substrate. The rate tends to be small, and charges tend to leak from the glass substrate surface. Therefore, it can be considered that the greater the amount of moisture retained on the glass substrate surface, the greater the effect of suppressing the charging of the glass substrate surface.

  An object of the present invention is to provide a glass substrate in which surface charging is effectively suppressed, and a method for producing the glass substrate.

The glass substrate which concerns on this invention is a glass substrate for flat panel displays in which a semiconductor element or a color filter is formed. The glass substrate includes a first surface and a second surface. The first surface is a surface on which a semiconductor element or a color filter is formed. The second surface is a surface opposite to the first surface. The area increment of the second surface is at least 0.05%. The area increment rate is calculated based on the actual area S ₁ and the measured area S _{0 by} the following formula (I):
dS = [(S ₁ −S ₀ ) / S ₀ ] × 100 (%) (I)
The value dS calculated by The actual area S ₁ is a surface area calculated from three-dimensional data obtained by measuring a 1 μm × 1 μm scan range of the second surface using an atomic force microscope, and is a surface area in the scan range of the second surface. is there. The measurement area S ₀ is the area of the geometric shape of the scan range.

  The glass substrate has a second surface that has been subjected to a surface treatment that increases the surface area by wet etching or the like. This surface treatment increases the amount of moisture retained on the second surface. The greater the amount of moisture held on the second surface of the glass substrate, the smaller the surface resistivity of the glass substrate, and the more likely the charge leaks from the glass substrate surface. Therefore, this glass substrate is effectively suppressed from being charged.

  The area increment rate is preferably at least 0.15%.

The manufacturing method of the glass substrate which concerns on this invention is a manufacturing method of the glass substrate for flat panel displays in which a semiconductor element or a color filter is formed. The method for manufacturing a glass substrate includes an etching process. The etching step etches the second surface, which is the surface opposite to the first surface, which is the surface of the glass substrate on which the semiconductor element or the color filter is formed. The area increment of the second surface is at least 0.05%. The area increment rate is expressed by the following formula (II) based on the actual area S ₁ and the measured area S ₀ :
dS = [(S ₁ −S ₀ ) / S ₀ ] × 100 (%) (II)
The value dS calculated by The actual area S ₁ is a surface area calculated from three-dimensional data obtained by measuring the 1 μm × 1 μm scan range of the second surface using an atomic force microscope, and is etched in the etching process. The surface area in the scan range. The measurement area S ₀ is the area of the geometric shape of the scan range.

  In this glass substrate manufacturing method, the second surface of the glass substrate is subjected to a surface treatment that increases the surface area by etching. This surface treatment increases the amount of moisture retained on the second surface. The greater the amount of moisture held on the second surface of the glass substrate, the smaller the surface resistivity of the glass substrate, and the more likely the charge leaks from the glass substrate surface. Therefore, in this glass substrate manufacturing method, charging of the glass substrate is effectively suppressed.

  The area increment rate is preferably at least 0.15%.

  In the etching step, the second surface is preferably etched with an etchant containing hydrogen fluoride.

  In the etching step, the first surface is preferably etched together with the second surface. In this method for manufacturing a glass substrate, charging of the first surface and the second surface of the glass substrate is effectively suppressed.

  As for the glass substrate manufactured by the glass substrate which concerns on this invention, and the manufacturing method of a glass substrate, surface charging is suppressed effectively.

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 a figure which shows an example of a dry etching apparatus. It is a figure which shows an example of a wet etching apparatus.

(1) Outline of Glass Substrate Manufacturing Method An embodiment of the present invention will be described with reference to the drawings. The glass substrate 10 manufactured by the glass substrate manufacturing method used in the present embodiment is used for manufacturing flat panel displays (FPD) such as liquid crystal displays, plasma displays, and organic EL displays. The glass substrate 10 has a thickness of 0.2 mm to 0.8 mm, for example, and has a size of 680 mm to 2200 mm in length and 880 mm to 2500 mm in width.

  FIG. 1 is a cross-sectional view of the glass substrate 10. The glass substrate 10 has an element forming surface 12a which is one main surface and a roughened surface 12b which is the other main surface. The element forming surface 12a is a surface on which a plurality of thin films including a semiconductor element such as a TFT, a polysilicon thin film, an ITO (Indium Thin Oxide) thin film, and a color filter are formed in the FPD manufacturing process. Therefore, in general, the element formation surface 12a is an extremely smooth surface having an arithmetic average roughness Ra of 0.2 nm or less. On the other hand, the roughened surface 12b is a surface on which minute irregularities are formed by an etching process in the manufacturing process of the glass substrate 10, as will be described later. In the present embodiment, the roughened surface 12b of the glass substrate 10 is surface-treated by etching.

  An example of the glass substrate 10 is 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 : 5% 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 .
The glass having the above composition is allowed to contain other trace components in the range of less than 0.1% by mass.

  The glass substrate 10 is formed by a float method, a down draw method, or the like. In the present embodiment, a 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 melting process (step S10), a clarification process (step S20), a stirring process (step S30), a molding process (step S40), and a slow cooling process (step S50). The plate-making process (step S60), the cutting process (step S70), the roughening process (step S80), and the end face machining process (step S90). The melting step S10, the refining step S20, the stirring step S30, the forming step S40, the slow cooling step S50, the plate-drawing step S60, and the cutting step S70 are substrate manufactures in which the glass substrate 10 is manufactured from glass raw materials. It is a process. The roughening step S80 is a surface treatment step in which the roughened surface 12b of the glass substrate 10 is roughened by etching. Next, an outline of each process will be described.

  In the melting step S10, the glass raw material is melted by a heating means such as a burner in the melting tank, and high-temperature molten glass at 1500 ° C. to 1600 ° C. is generated. The glass raw material is prepared so that a glass having a desired composition can be substantially obtained. Here, “substantially” means that the presence of other trace components is allowed in the range of less than 0.1% by mass. The molten glass is sent to a downstream process from an outlet provided at the bottom of the melting tank.

In the clarification step S20, the molten glass is clarified by further raising the temperature of the molten glass generated in the melting step S10 in the clarification tank. In the clarification tank, the temperature of the molten glass is raised to 1600 ° C to 1800 ° C, preferably 1650 ° C to 1750 ° C. In the clarification tank, fine bubbles of O ₂ , CO ₂ and SO ₂ contained in the molten glass grow by absorbing O ₂ generated by the reduction of the fining agent such as SnO ₂ contained in the glass raw material. Ascend to the liquid level.

  In the stirring step S30, the molten glass clarified in the clarification step S20 is stirred and chemically and thermally homogenized in the stirring tank. In the stirring tank, the molten glass is stirred by a rotating shaft stirrer while flowing in the vertical direction, and sent to a downstream process from an outlet provided at the bottom of the stirring tank. Moreover, in stirring process S30, the glass component which has specific gravity different from the average specific gravity of molten glass, such as a zirconia rich molten glass, is removed from a stirring tank.

  In the forming step S40, a glass ribbon is formed from the molten glass stirred in the stirring step S30 by the overflow downdraw method. Specifically, the molten glass that overflows from the upper part of the forming cell flows downward along the side wall of the forming cell, and joins at the lower end of the forming cell, whereby the glass ribbon is continuously formed. 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 S40.

  In the slow cooling step S50, the glass ribbon continuously produced in the forming step S40 is gradually cooled to the annealing point or lower while the temperature is controlled so as not to cause distortion and warpage.

  In the plate-drawing step S60, the glass ribbon slowly cooled in the slow cooling step S50 is cut for each predetermined length.

  In cutting process S70, the glass ribbon cut | disconnected for every predetermined length by the plate-drawing process S60 is cut | disconnected by the predetermined magnitude | size, and the glass substrate 10 is obtained.

  In the roughening step S80, as will be described later, a surface treatment for increasing the surface roughness of the roughened surface 12b of the glass substrate 10 obtained in the cutting step S70 is performed. The roughening step S80 mainly includes a cleaning step for cleaning the roughened surface 12b of the glass substrate 10 and an etching step for etching the roughened surface 12b cleaned in the cleaning step.

  In the end face processing step S90, the end portion of the glass substrate 10 whose surface is roughened in the roughening step S80 is polished and ground.

  In addition, the washing | cleaning process and test | inspection process of the glass substrate 10 are performed after end surface processing process S90. Details of the cleaning process and the inspection process are omitted. Finally, the glass substrate 10 is packed and shipped to the FPD manufacturer. The FPD manufacturer manufactures an FPD by forming a thin film made of TFT or the like on the element forming surface 12a of the glass substrate 10.

(2) Details of Roughening Step Next, the cleaning step and the etching step of the roughened surface 12b performed in the roughening step S80 will be described.

(2-1) Cleaning Step In the cleaning step, the roughened surface 12b is cleaned. The cleaning process is, for example, a plasma cleaning process. In the plasma cleaning process, for example, air, which is a mixed gas of nitrogen and oxygen, and a gas activated in a plasma state generated from argon are used.

  In the plasma cleaning process, the gas activated in the plasma state is sprayed onto the roughened surface 12b of the glass substrate 10, whereby the organic thin film adhering to the roughened surface 12b is removed. The organic thin film functions as a mask in a later etching process. Therefore, before the etching process, a cleaning process for removing the organic thin film from the roughened surface 12b is performed.

  In the cleaning process of the roughened surface 12b, instead of performing the plasma cleaning process, an organic gas thin film can be removed by performing an ozone gas spray process and an ultraviolet irradiation process. In the cleaning step, at least the organic thin film may be removed by oxidizing or modifying the organic matter. Note that the cleaning process performed before the surface treatment in the etching process is not an essential process, and is not necessary if the cleanliness of the roughened surface 12b to be surface-treated is high.

(2-2) Etching Step In the etching step, the roughened surface 12b is etched. The etching process is, for example, a dry etching process or a wet etching process. In the etching process, a fluorine-based etchant is used, and in particular, an etchant containing hydrogen fluoride is preferably used.

  FIG. 3 is a diagram illustrating an example of a dry etching apparatus. The dry etching apparatus 30 mainly includes an etching nozzle 31 and a conveyance roller 32. The glass substrate 10 is conveyed by the conveyance roller 32. The roughened surface 12 b of the glass substrate 10 is a surface that contacts the transport roller 32. The etching nozzle 31 is a slit-like nozzle that extends in the width direction of the glass substrate 10. The etching nozzle 31 sprays an etchant on the roughened surface 12b of the glass substrate 10 to be conveyed. The etchant is, for example, gaseous hydrogen fluoride generated by passing a mixed gas of carbon tetrafluoride and water through a carrier gas in a plasma state. Nitrogen, argon, etc. are used as carrier gas.

  FIG. 4 is a diagram illustrating an example of a wet etching apparatus. The wet etching apparatus 40 mainly includes a conveyance roller 42, a roughening roller 44, a contact roller 46, and an etchant tank 48. The glass substrate 10 is transported by the transport roller 42 and the roughening roller 44. The roughened surface 12 b of the glass substrate 10 is a surface in contact with the conveying roller 42 and the roughened roller 44. The outer peripheral surface of the roughening roller 44 is made of sponge. A part of the outer peripheral surface of the roughening roller 44 is immersed in an etching solution 49 stored in an etchant tank 48. The etchant 49 is, for example, hydrofluoric acid. The surface of the roughening roller 44 absorbs the etching solution 49. Therefore, the etching liquid 49 absorbed by the roughening roller 44 comes into contact with the roughened surface 12b of the glass substrate 10, and thus the etching liquid 49 is applied to the roughened surface 12b. In order to adjust the amount of the etching solution 49 applied to the roughened surface 12 b, a part of the etching solution 49 absorbed by the roughening roller 44 presses the surface of the roughening roller 44. Squeezed by. Further, by blowing air or the like to the element forming surface 12a of the glass substrate 10, the pressure at which the roughened surface 12b of the glass substrate 10 and the roughening roller 44 come into contact can be kept high.

  In the etching step, the time required for the etching process can be adjusted by adjusting the conveyance speed of the glass substrate 10, and the amount of the etchant adhering to the roughened surface 12b can be adjusted. Before the etching process is performed, the roughened surface 12b of the glass substrate 10 is uniformly etched because the organic thin film is removed in the cleaning process.

The surface area of the roughened surface 12b after the etching process is larger than the surface area of the roughened surface 12b before the etching process. The area increment of the roughened surface 12b is at least 0.05%, preferably at least 0.15%. The area increment rate is expressed by the following formula (III) based on the actual area S ₁ and the measured area S ₀ :
dS = [(S ₁ −S ₀ ) / S ₀ ] × 100 (%) (III)
The value dS calculated by The actual area S ₁ is a surface area calculated from three-dimensional data obtained by measuring a 1 μm × 1 μm scan range of the roughened surface 12b using an atomic force microscope, and is a scan of the roughened surface 12b. The surface area in the range. The measurement area S ₀ is the area of the geometric shape of the scan range.

(3) Features Water molecules present in the atmosphere around the glass substrate 10 adhere to the surface of the glass substrate 10. Specifically, water molecules are physically adsorbed on the surface of the glass substrate 10. Further, water molecules are hydrogen-bonded to the hydroxyl group of the silanol structure (Si—OH) present on the surface of the glass substrate 10. Therefore, the surface of the glass substrate 10 can retain moisture, and a film of water molecules is formed on the surface of the glass substrate 10.

  In the water molecule film, water molecules in the lower layer close to the surface of the glass substrate 10 are difficult to move due to the adsorption force with the surface of the glass substrate 10. On the other hand, since the water molecules in the upper layer have a small adsorption force with the surface of the glass substrate 10, they can easily move through the water molecule film formed on the surface of the glass substrate 10.

In water, some of the water molecules are dissociated into H ⁺ ions and OH ⁻ ions. In water, there are H ₃ O ^+, H ₉ O ₄ ^{+ and the} like generated when water molecules associate with H ⁺ ions. Therefore, in the upper layer of the water molecule film formed on the surface of the glass substrate 10, H ₃ O ^+, H ₉ O ₄ ^{+ and the} like move along the surface of the glass substrate 10.

  In the present embodiment, the roughened surface 12b of the glass substrate 10 is subjected to a roughening process by etching. The surface area of the roughened surface 12b is increased by the roughening treatment. As the surface area of the roughened surface 12b increases, the number of water molecules attached to the roughened surface 12b increases. Accordingly, the amount of water retained by the roughened surface 12b of the glass substrate 10 is larger than the amount of water retained by the roughened surface 12b before being etched.

And the film | membrane of the water molecule formed in the roughening surface 12b becomes thick, so that the moisture content hold | maintained on the roughening surface 12b of the glass substrate 10 is large. Therefore, as the amount of moisture retained on the roughened surface 12b increases, the number of H ₃ O ⁺ and H ₉ O ₄ ⁺ that can easily move in the water molecule film increases. The surface resistance of the surface 12b is reduced. The smaller the surface resistance of the roughened surface 12b of the glass substrate 10, the easier the charges move on the roughened surface 12b. Therefore, the smaller the surface resistance of the roughened surface 12b, the easier the charge leaks from the roughened surface 12b, and the charging of the roughened surface 12b is more effectively suppressed. That is, by performing the etching process on the roughened surface 12b of the glass substrate 10 so that the surface area of the roughened surface 12b increases, static electricity accumulated in the glass substrate 10 is released from the roughened surface 12b. It becomes easy.

  In the flat panel display manufacturing process, a thin film having a plurality of layers made of a semiconductor element such as a TFT, a polysilicon thin film, an ITO thin film, or the like is formed on the element forming surface 12a of the glass substrate 10. Each time a film forming process is performed on the element forming surface 12a, the glass substrate 10 is removed from the susceptor in the reaction container of the semiconductor manufacturing apparatus. At this time, peeling electrification occurs between the metal surface of the susceptor on which the glass substrate 10 is placed and the roughened surface 12b of the glass substrate 10. When static electricity is accumulated on the glass substrate 10 due to peeling charging, the roughened surface 12b of the glass substrate 10 is likely to stick to the metal surface of the susceptor due to static electricity. Thereby, when removing the glass substrate 10 from a susceptor, the glass substrate 10 may be damaged by giving an excessive force to the glass substrate 10. In addition, a voltage caused by static electricity accumulated due to peeling charging may destroy a semiconductor element or the like formed on the element formation surface 12 a of the glass substrate 10.

  In the glass substrate manufacturing method according to the present embodiment, static electricity accumulated in the glass substrate 10 is easily released from the roughened surface 12b, and charging of the roughened surface 12b is effectively suppressed. Therefore, in the manufacturing process of the flat panel display, it is possible to effectively suppress the breakage of the glass substrate 10 and the destruction of the semiconductor elements and the like formed on the surface of the glass substrate 10. Further, it is possible to prevent particles from adhering to the surface of the glass substrate 10 due to electrostatic charging of the glass substrate 10, and to prevent color filter peeling and wiring electrode peeling due to the adhesion of particles.

(4) Modifications Although the method for manufacturing a glass substrate according to the present invention has been described above, the present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the spirit of the present invention. May be. Of course, the present invention is effective not only on a glass substrate on which a semiconductor element is formed on the surface but also on a glass substrate on which a color filter is formed on the surface.

(4-1) Modification A
In the present embodiment, only the roughened surface 12b of the glass substrate 10 is subjected to a roughening process by etching. However, the element forming surface 12a and the roughened surface 12b of the glass substrate 10 may be roughened by etching. Thereby, not only the charging of the roughened surface 12b but also the charging of the element forming surface 12a is effectively suppressed, so that the static electricity accumulated in the glass substrate 10 is more easily released from the roughened surface 12b.

  In addition, since a semiconductor element such as a TFT (Thin Film Transistor) is formed on the element forming surface 12a of the glass substrate 10, the element forming surface 12a is roughened to the extent that the formation of the semiconductor element is not hindered. Is preferred. Specifically, the roughened element forming surface 12a preferably has an Ra (arithmetic average roughness) of less than 2.0 nm.

(4-2) Modification B
In the present embodiment, the roughened surface 12b of the glass substrate 10 is cleaned by a cleaning process and then roughened by an etching process. However, a surface treatment for polishing the roughened surface 12b by a sandblasting method or the like may be performed before the roughened surface 12b is etched. Also in this case, the roughened surface 12b is polished and then etched using a fluorine-based etchant in an etching process.

(4-3) Modification C
In the present embodiment, as an example of the wet etching process for the roughened surface 12b of the glass substrate 10, the roller etching process for applying an etching solution to the roughened surface 12b using the roughening roller 44 has been described. However, the wet etching process of the roughened surface 12b may be, for example, a shower etching process and a dip etching process.

  In the shower etching process, fine droplets of the etching solution are sprayed on the roughened surface 12b of the glass substrate 10. As a result, the etchant uniformly adheres to the roughened surface 12b, and the roughened surface 12b is roughened.

  In the dip etching process, the entire glass substrate 10 is immersed in an etching solution tank in which an etching solution is stored. Thereby, the element formation surface 12a and the roughened surface 12b of the glass substrate 10 are roughened.

(5) Example As an example of the method for producing a glass substrate according to the present invention, one main surface of the glass substrate was subjected to a roughening treatment, and a change in surface area was measured. Specifically, an etching process was performed on a plurality of glass substrates under different conditions, and the surface area of the etched surface was measured. Moreover, the surface area of the surface of the glass substrate which has not been etched is measured. Further, the chargeability and leakage of the glass substrate surface were measured. As the glass substrate, a glass substrate for a liquid crystal display device using boroaluminosilicate glass was used. Evaluation of the charging property of the glass substrate was a glass substrate having a size of 730 mm × 920 mm and a thickness of 0.5 mm.

  First, one main surface of the glass substrate was cleaned using a plasma cleaning apparatus. In the cleaning step, plasma surface argon gas was sprayed on the surface of the glass substrate at a predetermined amount per minute to clean the surface of the glass substrate.

  Next, the surface of the cleaned glass substrate was roughened by a dry etching process or a wet etching process. In the dry etching process, hydrogen fluoride as an etching gas was generated by passing a mixed gas of carbon tetrafluoride and water through a carrier gas composed of argon in a plasma state. And the produced | generated etching gas was sprayed on the surface of the glass substrate, and the surface of the glass substrate was etched. In the wet etching process, any of the above-described roller etching process, shower etching process, and dip etching process was performed.

  Next, a square sample having a side of 50 mm was cut out from the roughened glass substrate, and the etched glass substrate surface was evaluated.

First, the increase rate of the glass substrate surface area by the etching treatment was calculated. Specifically, a 1 μm × 1 μm scan range of the glass substrate sample was measured by 256 points × 256 points using an atomic force microscope, and the surface area of the scan range was calculated from the obtained three-dimensional data. The actual surface area of the calculated scan range is defined as an actual area S ₁ . In addition, a measurement area S ₀ that is an area of a geometric shape in the scan range was calculated. Then, the area increment rate dS was calculated from the actual area S ₁ and the measured area S ₀ based on the above formula (III).

  Second, the chargeability of the glass substrate surface was evaluated. Evaluation of charging property was performed in an environment of a temperature of 25 ° C. and a humidity of 50%. Specifically, first, the glass substrate was placed on the table, and the glass substrate and the table surface were brought into close contact with each other for a predetermined time by vacuum suction. Next, using a pin, the glass substrate was lifted and peeled off from the table surface. Next, the amount of charge on the surface of the glass substrate was measured using a surface potentiometer (manufactured by OMRON Corporation). The above process was repeated four times at predetermined intervals to measure the maximum charge amount on the glass substrate surface. And it was determined that the smaller the absolute value of the maximum charge amount on the glass substrate surface, the lower the chargeability of the glass substrate surface.

  Third, the leakage of the glass substrate surface was evaluated. In the evaluation of electrical leakage, the surface of the glass substrate was charged to a predetermined potential, and the glass substrate was peeled off from the table surface, that is, the glass substrate was left in a lifted-up state. Next, the rate at which the amount of charge on the surface of the glass substrate decreased was measured. And it was determined that the higher the rate at which the amount of charge on the surface of the glass substrate decreased, the higher the leakage of the glass substrate surface.

  Table 1 below shows the etching treatment method, area increment rate, chargeability evaluation results, and electrical leakage for the seven glass substrates of Examples 1-4, Comparative Example 1, Comparative Example 2, and Reference Example. Sexual measurement results are shown. The reference example relates to a glass substrate that has been subjected to an etching process after the process of polishing the surface. Note that the etchant used for the etching treatment is hydrogen fluoride.

  In Table 1, “treatment method” represents a method for etching the glass substrate surface. The concentration of the used etchant is described in the “treatment method” column of Examples 1, 2, 4, Comparative Example 2 and Reference Example. For example, 2000 ppm hydrofluoric acid was used in the roll etching process of Example 1. In the dip etching process of Example 4, both surfaces of the glass substrate were etched. In the reference example, the process of polishing the surface of the glass substrate using a cerium oxide abrasive was performed before the shower etching process. In Comparative Example 1, the glass substrate surface was not etched. In Table 1, “Chargeability” is represented by “◯”, “Δ”, and “X” in ascending order of absolute value of the maximum charge amount on the glass substrate surface in the evaluation of the charge amount on the glass substrate surface.

  According to Table 1, as shown in Examples 1 to 4, high leakage was confirmed when the area increment rate by the etching treatment was 0.10% or more. In addition, as shown in the reference example, a certain level of leakage was confirmed even when the area increment rate by the etching process was 0.05%. In addition, a correlation was confirmed between chargeability and leakage.

  Furthermore, when the evaluation of the chargeability of Examples 1 to 4 was compared by increasing the number of times the glass substrate was peeled off, it was confirmed that the chargeability was suppressed in Examples 1, 2, and 4 as compared with Example 3. In Examples 2 and 4, it was confirmed that the chargeability was suppressed as compared with Examples 1 and 3. Further, in Example 2 in which one side was roughened and Example 4 in which both sides were roughened, the effect of suppressing the chargeability was almost the same.

  From the above, it was confirmed that the leakage property on the surface of the glass substrate is improved by performing the etching process so that the surface area of the glass substrate is increased in the roughening step of the glass substrate. That is, it has been found that the larger the surface area of the glass substrate, the more easily the surface charge is suppressed because the charge is more likely to leak from the surface even when peeling charge is generated on the surface of the glass substrate.

10 Glass substrate 12a Element formation surface (first surface)
12b Roughened surface (second surface)

JP 2005-255478 A

Journal of the Electrostatic Society, Vol. 18, No. 4 (1994) pp. 364-370

Claims (6)

A glass substrate for a flat panel display on which a semiconductor element or a color filter is formed,
A first surface on which a semiconductor element or a color filter is formed;
A second surface that is a surface opposite to the first surface;
With
A surface area calculated from three-dimensional data obtained by measuring a scan range of 1 μm × 1 μm of the second surface using an atomic force microscope, and an actual area that is a surface area of the second surface in the scan range Based on S ₁ and the measurement area S ₀ which is the area of the geometric shape of the scan range, the following formula (I):
dS = [(S ₁ −S ₀ ) / S ₀ ] × 100 (%) (I)
The area increment rate which is the value dS calculated by is at least 0.05%,
Glass substrate. The area increment is at least 0.15%;
The glass substrate according to claim 1. A method for producing a glass substrate for a flat panel display in which a semiconductor element or a color filter is formed,
An etching step of etching a second surface which is a surface opposite to the first surface which is a surface of a glass substrate on which a semiconductor element or a color filter is formed;
The surface area calculated from three-dimensional data obtained by measuring a scan range of 1 μm × 1 μm of the second surface using an atomic force microscope, and the scan of the second surface etched in the etching step Based on the actual area S ₁ which is the surface area in the range and the measured area S ₀ which is the area of the geometric shape of the scan range, the following formula (II):
dS = [(S ₁ −S ₀ ) / S ₀ ] × 100 (%) (II)
The area increment rate which is the value dS calculated by is at least 0.05%,
A method for producing a glass substrate. The area increment is at least 0.15%;
The manufacturing method of the glass substrate of Claim 3. In the etching step, the second surface is etched by an etchant containing hydrogen fluoride.
The manufacturing method of the glass substrate of Claim 3 or 4. In the etching step, the first surface is etched together with the second surface.
The manufacturing method of the glass substrate of any one of Claims 3-5.

Images