JP2016047775A - Float glass with lamination film, and production method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide float glass with a lamination film including a low resistant fluorine-doped tin oxide layer and a production method of the same by properly controlling temperature of a glass ribbon, in forming a lamination film by an on-line CVD method using a plurality of injectors arranged in a slow cooling furnace.SOLUTION: In float glass with a lamination film, the lamination film is formed on a glass ribbon by a CVD method using a plurality of injectors arranged in a slow cooling furnace. When a glass transition temperature is represented by Tg and a glass strain temperature is represented by Ts, the lamination film is formed at Tg+50°C or lower, and at least two or more layers of the lamination film are formed in a temperature range of Tg+50°C to Ts. Further, a depression temperature K1 per unit length of the glass ribbon in a temperature range for forming all layers of the lamination film satisfies inequality 0°C/m<K1<10°C/m, and the lamination film includes a fluorine-doped tin oxide layer having specific resistivity of 4.7×10Ω cm or less, and carrier concentration of 2.5×10cmor more.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a float glass with a laminated film, and more particularly to a float glass with a laminated film in which a laminated film is formed on a glass ribbon in a slow cooling furnace by an on-line CVD (Chemical Vapor Deposition) method.

As a method for forming a film on a glass ribbon by an on-line CVD method, for example, methods described in Patent Documents 1 to 3 are known.
Patent Document 1 discloses that an oxide containing silicon and oxygen is formed on a glass ribbon in a float bath by a CVD method. In this case, it is disclosed that an unsaturated hydrocarbon compound and carbon dioxide are used as an oxygen source in order to prevent oxidation of molten metal in the float bath by oxygen gas.
Patent Document 2 discloses a method of sequentially forming a silicon dioxide film and a tin oxide film on a glass ribbon at a coating station (injector) disposed in a float bath and a coating station disposed in a slow cooling furnace.
Patent Document 3 discloses a method of forming a film on a glass ribbon by providing a nozzle (injector) in a region between the float bath outlet and the annealing furnace inlet.

JP-A-1-201046 JP-A-3-33036 Japanese Patent Publication No. 4-35558

In the float bath, the periphery of the molten metal is usually a non-oxidizing atmosphere to prevent oxidation of the molten metal. Further, the glass ribbon is in a soft state in the float bath, and when the film is formed on the soft glass ribbon in the float bath by the CVD method, the glass ribbon is not easily warped or cracked due to a temperature difference.
Patent Document 1 discloses that an unsaturated hydrocarbon compound and carbon dioxide are used as an oxygen gas source for preventing oxidation of molten metal in a float bath. This is because oxygen gas cannot be used when forming an oxide film in a non-oxidizing atmosphere, and a reaction gas containing oxygen molecules needs to be used. However, when an oxide containing silicon and oxygen is formed by this method, hydrocarbon or carbon dioxide (C) derived from carbon dioxide is mixed into the oxide film. As a result, the absorption of the film is increased, and the film has a reduced transmittance as compared with the film not containing carbon.
For this reason, there is a problem that the film quality deteriorates when an oxide film is formed in the float bath by the CVD method, and the film formation outside the float bath is desired.

  In Patent Document 2, when a coating station is provided in a slow cooling furnace, a problem arises because the temperature conditions for film formation are different from the temperature conditions for slow cooling of the glass ribbon, and a multilayer coating is formed. Points out that the problem is more complicated. For this reason, Patent Document 2 recommends that the premixed oxygen and the coating precursor are brought into contact with the glass ribbon in the float bath. However, this method requires a seal to seal the oxygen gas and complicates the apparatus. Also, when a coating station is provided in the slow cooling furnace and a metal oxide film is to be formed on the glass ribbon, the heat exchange between the glass ribbon and the injector causes a rapid heat removal from the glass ribbon compared to the case without the coating station. May occur, and the glass ribbon may be deformed or scratches and cracks may occur. In particular, the greater the number of coating stations, the greater the risk that scratches and cracks will occur, and the warped glass ribbon may come into contact with the coating stations and cause scratches and cracks with the glass.

  For this reason, Patent Document 2 discloses that when one or more coating stations are provided in a slow cooling furnace when forming a multilayer coating, there is a problem that different temperature controls must be established. On the other hand, there is no specific disclosure of an appropriate temperature management method in the case where a plurality of coating stations are arranged in a slow cooling furnace.

  Patent Document 3 discloses that a nozzle (injector) is provided in a region between the float bath outlet and the annealing furnace inlet so as to cover the entire width of the glass. However, even if the conventional float manufacturing apparatus is used as it is, there is not sufficient space for disposing the nozzle between the float bath and the slow cooling furnace. In addition, the temperature of the glass ribbon is not controlled in the space between the float bath and the slow cooling furnace, and if a film is formed in the space between the float bath and the slow cooling furnace, the glass ribbon is rapidly changed due to heat exchange between the nozzle and the glass ribbon. There is a problem of heat removal.

The present invention has been made paying attention to the above-mentioned problems, and performs appropriate temperature management of a glass ribbon when forming a laminated film by an on-line CVD method using a plurality of injectors provided in a slow cooling furnace. A float glass with a laminated film including a fluorine-doped tin oxide layer having a specific resistance of 4.7 × 10 ⁻⁴ Ω · cm or less and a carrier concentration of 2.5 × 10 ²⁰ cm ⁻³ or more; A manufacturing method thereof is provided.

The present invention provides the following aspects.
(1) Using a glass manufacturing apparatus comprising a melting furnace for melting glass raw materials, a float bath for floating glass on a molten metal to form a glass ribbon, and a slow cooling furnace for gradually cooling the glass ribbon. A float glass with a laminated film to be manufactured,
The laminated film is formed on the glass ribbon by a plurality of injectors provided in the slow cooling furnace by a CVD method,
The laminated film is formed at Tg + 50 ° C. or lower when the glass transition temperature is Tg and the glass strain temperature is Ts, and at least two layers of the laminated film are formed in a temperature range of Tg + 50 ° C. to Ts. And
The temperature drop K1 per unit length of the glass ribbon in the temperature region for forming all the layers of the laminated film is 0 ° C./m<K1<10° C./m,
The laminated film includes a fluorine-doped tin oxide layer,
The fluorine-doped tin oxide layer has a laminated film characterized by having a specific resistance of 4.7 × 10 ⁻⁴ Ω · cm or less and a carrier concentration of 2.5 × 10 ²⁰ cm ⁻³ or more. Float glass.
(2) The float glass with a laminate film according to (1), wherein the laminate film has a mobility of 45 cm ² / V · s or more.
(3) The float glass with a laminated film according to (1) or (2), wherein at least two layers of the laminated film are formed in a temperature range of Tg + 50 ° C. to Tg.
(4) The float glass with a laminate film according to any one of (1) to (3), wherein the laminate film includes a silicon oxide layer.
(5) The float glass with a laminate film according to any one of (1) to (4), wherein the laminate film further includes a tin oxide layer that is not fluorine-doped.
(6) The tin oxide layer composed of the fluorine-doped tin oxide layer and the non-fluorine-doped tin oxide layer has a haze ratio of 10% or more at a wavelength of 550 nm at a thickness of 600 nm. The float glass with laminated film of description.
(7) The tin oxide layer composed of the fluorine-doped tin oxide layer and the non-fluorine-doped tin oxide layer has a haze ratio of 15% or more at a wavelength of 550 nm at a thickness of 730 nm. The float glass with laminated film of description.
(8) Using a glass manufacturing apparatus comprising a melting furnace for melting glass raw materials, a float bath for floating glass on a molten metal to form a glass ribbon, and a slow cooling furnace for gradually cooling the glass ribbon. A method for producing a laminated film-attached glass substrate by forming a laminated film on the glass ribbon with a plurality of injectors provided in the slow cooling furnace by a CVD method, and cutting the glass ribbon;
When the glass transition temperature is Tg and the glass strain temperature is Ts, the laminated film is formed at Tg + 50 ° C. or lower, and at least two layers of the laminated film are formed at a temperature range of Tg + 50 ° C. to Ts. ,
The temperature drop K1 per unit length of the glass ribbon in the temperature region for forming all the layers of the laminated film is 0 ° C./m<K1<10° C./m,
The laminated film includes a fluorine-doped tin oxide layer having a specific resistance of 4.7 × 10 ⁻⁴ Ω · cm or less, tin tetrachloride and hydrogen fluoride gas are in a molar ratio, and HF / SnCl ₄ = 1.0. A method for producing a glass substrate with a laminated film, wherein the fluorine-doped tin oxide layer is formed by spraying a raw material gas so as to be larger than that.

According to the float glass with a laminated film of the present invention and a method for producing the same, a laminated film including a fluorine-doped tin oxide layer is formed on the float glass in a slow cooling furnace of a glass production apparatus by an on-line CVD method while performing appropriate temperature control As a result, the specific resistance is 4.7 × 10 ⁻⁴ Ω · cm or less of the low resistance fluorine-doped oxidation compared to the fluorine-doped tin oxide layer of the float glass with a laminated film manufactured by the conventional off-line CVD method. A tin layer can be obtained. Thereby, it is applicable also to an optical member etc. which require a low resistance layer, such as Low-E glass.
Furthermore, by forming the laminated film online, the laminated film can be formed without reheating the glass once cooled, so that the manufacturing process can be simplified and the manufacturing cost can be suppressed. it can.

It is the schematic of one Embodiment of the glass manufacturing apparatus which can manufacture the float glass with a laminated film which concerns on this invention. It is sectional drawing of one Embodiment of the injector which can manufacture the float glass with a laminated film which concerns on this invention. It is sectional drawing of the transparent conductive substrate for solar cells which is one Embodiment of the float glass with a laminated film of this invention. It is a graph explaining temperature control of the glass ribbon in a slow cooling furnace. It is a graph which shows the relationship between the addition amount of hydrogen fluoride (HF), and the mobility of a carrier electron. It is a graph which shows the relationship between the addition amount of hydrogen fluoride (HF), and carrier concentration. It is a graph which shows the relationship between the addition amount of hydrogen fluoride (HF), and specific resistance.

First, with reference to FIG. 1, the one aspect | mode of the glass manufacturing apparatus which manufactures the float glass with a laminated film of this invention is demonstrated. In the following description, the term “film formation” may include the formation of at least one layer of a laminated film.
As shown in FIG. 1, a glass manufacturing apparatus 50 includes a melting furnace 51 that melts a glass raw material, a float bath 52 that floats the molten glass on molten tin to form a flat glass ribbon, a lift-out After the glass ribbon is pulled out from the float bath 52 by the roll 53, the slow cooling furnace 54 that gradually cools the glass ribbon by gradually lowering the temperature of the glass ribbon is provided.

  The slow cooling furnace 54 supplies, for example, the amount of heat whose output is controlled by a combustion gas or an electric heater to a required position in the furnace, and slowly cools the glass ribbon conveyed by the conveyance roller 55 to a temperature range close to room temperature. Thus, the residual stress inherent in the glass ribbon is eliminated, and the glass ribbon has an action of suppressing warpage and cracking. A plurality of injectors 60 are provided in the slow cooling furnace 54, and a laminated film is formed on the glass ribbon by a CVD method. The temperature of the glass ribbon when entering the slow cooling furnace 54 is often around 610 ° C. (Tg + 50 ° C.) in the case of soda lime silicate glass.

  The injector 60 includes six injectors 60a to 60f, and forms a laminated film on the glass ribbon to be conveyed. An electric heater 56 is provided between the injectors. In addition, the number of the injectors 60 is not limited to this, Preferably it exists in the range of 2-9 pieces, and an electric heater can also be increased / decreased as needed. These electric heaters prevent the temperature of the glass ribbon from excessively decreasing from the inlet to the outlet in the slow cooling furnace. On the other hand, the heater installed between the injectors can heat the glass ribbon between the injectors, but cannot heat the glass ribbon on the lower surface of the injector. By installing this heater, there is no influence on the temperature change of the glass ribbon cooled from the inlet to the outlet of the injector.

  The injector 60 (60a-60f) is arrange | positioned above the glass ribbon 70 on the opposite side to the conveyance roller 55 on both sides of the glass ribbon 70, as shown in FIG. Each injector is provided with a slit-like air outlet 61 that is elongated in a direction perpendicular to the glass ribbon conveyance direction at a substantially central portion of the lower surface 65, and exhaust that extends in parallel with the air outlet 61 on both sides in the front-rear direction of the air outlet 61. A mouth 62 is provided.

  In the blower outlet 61, the first orifice 61a located in the center and the first orifice 61a are positioned in the front-rear direction so as to incline the flow path from the source gas supply source toward the first orifice 61a. The configured second and third orifices 61b and 61c are opened. The widths of the air outlet 61 and the air outlet 62 are set to be equal to or larger than the width of the glass ribbon 70. Reference numerals 66a and 66b denote cooling ducts, which circulate a cooling medium such as cooling gas or oil, and maintain the injector 60 at an optimum temperature, for example, 100 to 220 ° C. (measured on the lower surface of the injector). The lower surface of the injector 60 is a surface in contact with the raw material gas. If the temperature is too high, the raw material gas in contact with the lower surface of the injector 60 reacts with heat and adheres to form an unnecessary film. For this reason, the upper limit is preferably 250 ° C. or less. On the other hand, if the temperature is too low, the amount of heat exchange with the glass ribbon increases, causing a rapid temperature drop of the glass ribbon. For this reason, the lower limit is desirably 100 ° C. or higher.

  The injector 60 is disposed above the glass ribbon 70 with an interval of 3 mm to 30 mm. Therefore, the lower surface 65 of the injector 60 is opposed to the glass ribbon 70 conveyed into the slow cooling furnace 54 through a gap of 3 mm to 30 mm. The smaller the gap, the more advantageous the film thickness, film quality, and film formation speed during film formation. However, when the gap fluctuates due to warping or vibration of the glass ribbon, the influence on the film thickness and film quality increases. In addition, when the gap is large, the efficiency of the raw material during film formation is reduced. Considering the film thickness, film quality, and film forming speed, the gap is preferably 4 to 12 mm, more preferably 5 to 10 mm.

  From the first orifice 61a, a gas containing the main raw material of the compound forming the oxide film is blown out. Further, a reactive gas (a gas that becomes an oxygen source) for forming the oxide film is blown out from the second and third orifices 61b and 61c. The exhaust port 62 exhausts excess gas after the CVD reaction.

  The composition of the glass ribbon can be appropriately selected as long as it can be molded by the float process, and examples thereof include soda lime silicate glass, aluminosilicate glass, lithium aluminosilicate glass, borosilicate glass, and alkali-free glass. Among them, soda lime silicate glass is preferable because it is colorless and transparent and inexpensive.

The thickness of the glass ribbon can be selected as appropriate, and the glass thickness is preferably 0.1 to 6.0 mm. In thin glass, the temperature difference between the front and back is less likely to occur, so there is little warping to the injector side. Thick glass tends to cause a temperature difference between the front and back, but because of its own weight, it works to reduce warpage. For this reason, even if the glass thickness changes between 0.1 and 6.0 mm, the warpage amount itself does not change so much.
In addition, the glass ribbon may have one or more thin films formed in advance on the surface thereof, such as the formation of a base layer in a float bath, in a step before the slow cooling furnace within a range not impairing the effects of the present invention. .

  The type, configuration, and the like of the laminated film to be formed are not particularly limited and can be selected as appropriate. In the following description, an example of forming a transparent conductive film for a solar cell will be described. Examples of uses other than the transparent conductive film for solar cells include an antireflection film and a heat ray reflective film.

  FIG. 3 is a cross-sectional view of one embodiment of a transparent conductive substrate for a solar cell manufactured by the method for manufacturing a float glass with a laminated film of the present invention. It is illustrated so that the incident light side of the transparent conductive substrate for solar cell is located on the lower side of FIG.

  As shown in FIG. 3, the transparent conductive substrate 10 for a solar cell includes a titanium oxide layer 14, a silicon oxide layer 16, and a first tin oxide as a laminated film 13 on the base 12 from the base 12 side. It has the layer 18 (tin oxide layer not fluorine-doped) and the second tin oxide layer 20 (fluorine-doped tin oxide layer) in this order.

  The material of the substrate 12 is not particularly limited, and examples thereof include soda lime silicate glass, aluminosilicate glass, lithium aluminosilicate glass, borosilicate glass, and alkali-free glass. Among them, soda lime silicate glass is preferable because it is colorless and transparent and inexpensive.

  The thickness of the substrate 12 is preferably 0.1 to 6.0 mm. Within the above range, the balance between mechanical strength and translucency is excellent.

  In FIG. 3, a titanium oxide layer 14 is formed on the substrate 12. In the present invention, the aspect having the titanium oxide layer 14 between the base 12 and the silicon oxide layer 16 is the base 12 and the tin oxide layer 18 generated by the difference in refractive index between the base 12 and the tin oxide layers 18 and 20. This is one of the preferred embodiments because the reflection at the interface with 20 can be suppressed.

  In order to form the laminated film 13 of the transparent conductive substrate 10 for solar cells in the slow cooling furnace 54 of the glass manufacturing apparatus 50 shown in FIG. 1 by the CVD method, for example, the titanium oxide is formed on the glass ribbon by the first injector 60a. The layer 14 is formed, the silicon oxide layer 16 is formed by the second injector 60b, the first tin oxide layer 18 is formed by the third injector 60c, and the second is formed by the fourth to sixth injectors 60d to 60f. The tin oxide layer 20 is formed.

  In this case, vaporized tetraisopropoxy titanium is blown from the first orifice 61a and nitrogen gas is blown from the second and third orifices 61b and 61c at the outlet 61 of the first injector 60a. Thereby, tetraisopropoxy titanium undergoes a thermal decomposition reaction on the glass ribbon, and a titanium oxide layer 14 is formed on the surface of the glass ribbon being conveyed.

  At the outlet 61 of the second injector 60b, silane gas is blown from the first orifice 61a, and oxygen gas is blown from the second and third orifices 61b and 61c. Thereby, silane gas and oxygen gas are mixed and reacted on the titanium oxide 14 layer of the glass ribbon, and the silicon oxide layer 16 is formed on the surface of the titanium oxide layer 14 of the glass ribbon being conveyed.

  At the air outlet 61 of the third injector 60c, tin tetrachloride is blown from the first orifice 61a, and water vapor is blown from the second and third orifices 61b and 61c. Thereby, tin tetrachloride and water are mixed and reacted on the silicon oxide layer 16 of the glass ribbon, and the surface of the silicon oxide layer 16 of the glass ribbon being conveyed is not doped with fluorine. A tin oxide layer 18 is formed.

  At the outlets 61 of the fourth to sixth injectors 60d to 60f, tin tetrachloride is blown from the first orifice 61a, and hydrogen fluoride vaporized from the second and third orifices 61b and 61c is vaporized. Is sprayed. Thereby, tin tetrachloride, water, and hydrogen fluoride are mixed and reacted on the first tin oxide layer 18 of the glass ribbon, and the surface of the first tin oxide layer 18 of the glass ribbon in a state of being conveyed. A second tin oxide layer 20 doped with fluorine is formed.

The glass ribbon on which the second tin oxide layer 20 is formed is discharged from the slow cooling furnace 54 while being transported, cooled to near room temperature, cut into a desired size, and carried out as the transparent conductive substrate 10 for solar cells. The
As described above, it is preferable to form an oxide material such as titanium oxide, silicon oxide, or tin oxide in the film formation in the slow cooling furnace. This is because the atmosphere in the slow cooling furnace is air, and it is easy to supply oxygen molecules such as oxygen gas when forming oxides.

Here, the temperature control of the glass ribbon during film formation will be described with reference to FIG.
When the surface temperature of the glass ribbon when passing through the inlet of the slow cooling furnace 54 is Tin, the surface temperature of the glass ribbon when passing through the outlet of the slow cooling furnace 54 is Tout, the glass transition temperature is Tg, and the glass strain temperature is Ts, The surface temperature of the glass ribbon to be formed is Tg + 50 ° C. or less. If the surface temperature of the glass ribbon is higher than Tg + 50 ° C., the glass ribbon is liable to cause “scratch marks” and planar defects. Further, two or more layers of the laminated film are formed in a temperature region where the surface temperature of the glass ribbon is Tg + 50 ° C. to Ts. If an attempt is made to form all the laminated films at a temperature lower than Ts, the reaction of the raw material gas becomes insufficient, and there is a possibility that the film quality is deteriorated or the film forming speed is extremely reduced.
The laminated film 13 composed of the titanium oxide layer 14, the silicon oxide layer 16, the first tin oxide layer 18, and the second tin oxide layer 20 is preferably within a range of Tg + 50 ° C. to Ts, more preferably It is formed in a temperature range from Tg + 50 ° C. to Tg (when Tin is lower than Tg + 50 ° C., a temperature range from Tin to Tg).

  When the temperature of the glass ribbon falls below Tg, there is a risk that the glass ribbon flutters greatly due to shrinkage accompanying the change in the viscosity of the glass. However, by forming all layers in the temperature range from Tg + 50 ° C. to Tg, Regardless of the viscosity, flapping of the glass ribbon can be suppressed. In the case where the film is formed even in the temperature range from Tg to Ts, the number of layers formed in the temperature range from Tg to Ts is preferably 3 or less, and more preferably 2 or less.

  Since the injector 60 is maintained at a temperature lower than that of the glass ribbon, heat exchange is performed with the injector 60 during film formation, thereby lowering the temperature of the glass ribbon.

  When “the temperature drop per unit length of the glass ribbon in the temperature region where all laminated films are formed” is referred to as K1 (hereinafter, also simply referred to as temperature drop K1), 0 ° C./m<K1<10° C./m. Preferably, 1 ° C./m≦K1≦5° C./m, more preferably 2 ° C./m≦K1≦3.0° C./m. Note that the temperature drop K1 is the “temperature difference between the glass ribbon temperature at the inlet of the first injector and the glass ribbon temperature at the outlet of the last injector when forming the laminated film” in the temperature region where the laminated film is formed. Divided by the difference in the distance between the inlet position of the first injector and the outlet position of the last injector. If the temperature drop K1 is 10 ° C./m or more, the glass ribbon may be greatly deformed, and the glass ribbon may be damaged or cracked due to contact between the injector and the glass ribbon. If the temperature drop K1 is 0 ° C./m, the film is formed. In some cases, the glass ribbon is not gradually cooled in the slow cooling furnace 54, and the slow cooling furnace 54 is lengthened because the glass ribbon is gradually cooled after film formation.

  The glass ribbon whose temperature has been lowered by the injector 60 may be heated by an electric heater 56 or the like provided between the injectors 60 adjacent to each other in the glass ribbon conveyance direction to moderate the temperature drop K1. The amount of heat removed by the injector 60 also depends on the area of the lower surface 65 of the injector 60 that faces the glass ribbon. Therefore, the area of the lower surface 65 may be reduced in advance in order to reduce the amount of heat removal.

  The temperature of the glass ribbon used for calculating the temperature drop K1 is the temperature of the upper surface (film formation side) of the glass ribbon. The temperature difference between the upper surface of the glass ribbon and the lower surface of the position during film formation is preferably within 10 ° C. By setting the temperature difference between the upper surface of the glass ribbon and the lower surface at that position to be within 10 ° C., the warp of the glass ribbon below the injector is further suppressed, and the contact between the injector and the glass ribbon is more reliably suppressed.

  The glass ribbon is cooled under the above conditions and then cut into a desired size to obtain a substrate with a laminated film.

  Examples of the present invention will be described below.

1. Production of transparent conductive substrates for solar cells <On-line CVD>
In the production of a transparent conductive substrate for solar cells, six heaters are placed in a slow cooling furnace of a float glass manufacturing apparatus and an electric heater is placed between each injector, and a titanium oxide layer is formed on the glass ribbon by the first injector. A silicon oxide layer is formed with the second injector, a first tin oxide layer is formed with the third injector, and a second tin oxide layer 20 (three layers) is formed with the fourth to sixth injectors. A transparent conductive film for a solar cell in which these 6 layers were laminated on a glass substrate was formed. The temperature was measured with a contact-type K-type thermocouple (sensor, manufactured by Anri Keiki Co., Ltd .: 213K-TC1-ASP).

  Glass soda temperature at the inlet of the slow cooling furnace is 610 ° C., glass ribbon temperature at the outlet of the slow cooling furnace is 250 ° C., soda lime glass having a glass transition temperature Tg of 560 ° C. and a glass strain temperature Ts of 510 ° C. Three injectors were arranged in a region, that is, a temperature region of 610 ° C. to 560 ° C., and three layers (a titanium oxide layer, a silicon oxide layer, and a first tin oxide layer) were formed in a temperature region of Tg + 50 ° C. to Tg. In addition, three injectors were arranged in the temperature range from 560 ° C. to 510 ° C., and three layers (second tin oxide layers) were formed in the temperature range from Tg to Ts. At this time, the temperature drop per unit length in the temperature range from Tg + 50 ° C. to Tg is maintained at 2 ° C./m to 3 ° C./m and an average of 2.5 ° C./m by heating the glass ribbon with an electric heater. did. The temperature drop per unit length in the temperature range from Tg to Ts is also 2 ° C./m to 3 ° C./m, and the temperature drop K1 per unit length of the glass ribbon in the temperature range where all the laminated films are formed is 2 It was 5 ° C / m. At this time, the temperature of the glass ribbon cooled from the inlet to the outlet of each injector was 2 ° C to 8 ° C. Further, from the glass strain temperature of 510 ° C. to the outlet temperature of 250 ° C., the glass ribbon was gradually cooled at a temperature drop of 10 ° C./m to 14 ° C./m and an average of 13 ° C./m per unit length. After cooling, the glass ribbon was cut into a desired size to obtain a substrate with a transparent conductive film for solar cells.

  More specifically, in the first injector for forming the titanium oxide layer, vaporized tetraisopropoxy titanium (main raw material) as a raw material for the titanium oxide layer and nitrogen gas as a carrier gas on a glass ribbon at 585 ° C. (Sub-original) was sprayed to form a titanium oxide layer on the surface of the glass ribbon being conveyed. The temperature of the glass ribbon in online CVD (the above-mentioned 580 ° C. and the subsequent film formation temperature) is obtained by calculating the glass temperature at the center position of the injector from the temperature measurement positions at the front and rear of the injector in the transport direction. The thickness of the titanium oxide layer was 10 nm. Tetratitanium isopropoxide was vaporized by a vaporizer kept at about 170 ° C. and transported to the first injector through a stainless steel pipe. Table 1 shows the conditions for forming the titanium oxide layer.

  Subsequently, tin tetrachloride and water as raw materials for the first tin oxide layer were formed at 564 ° C. on a substrate on which a silicon oxide layer was formed to a thickness of 30 nm at 570 ° C. by a second injector at 564 ° C. Nitrogen gas as a carrier gas was sprayed to form a first tin oxide layer not doped with fluorine on the surface of the silicon oxide layer of the glass ribbon being conveyed. Tin tetrachloride was vaporized by a vaporizer kept at about 140 ° C. and transported to a third injector through stainless steel piping. Moreover, water transported the water vapor | steam obtained by boiling by heating to the 3rd injector by another stainless steel piping.

  Furthermore, on the glass ribbon on which the first tin oxide layer is formed on the surface, four raw materials for the second tin oxide layer are formed by the fourth to sixth injectors at 557 ° C., 551 ° C., and 546 ° C. A second tin oxide layer in which fluorine is doped on the surface of the first tin oxide layer of the glass ribbon being transported by blowing tin chloride, water, hydrogen fluoride, and nitrogen gas as a carrier gas. Formed. In addition, tin tetrachloride and water were transported to the fourth to sixth injectors by the same method as that for the first tin oxide layer. Further, hydrogen fluoride was supplied by transporting vaporized hydrogen fluoride to the fourth to sixth injectors through a stainless steel pipe and mixing with tin tetrachloride. The first tin oxide layer formed by the third injector, the second tin oxide layer (first layer) formed by the fourth injector, and the second tin oxide layer formed by the fifth injector ( The second layer) and the second tin oxide layer (third layer) formed by the sixth injector have the same film thickness.

  Table 2 shows the film forming conditions of the first tin oxide layer and the second tin oxide layer.

<Offline CVD>
A transparent conductive substrate for solar cells was manufactured using an off-line type CVD apparatus in which five injectors were attached to a tunnel-type heating furnace that transports the substrate by a mesh belt. Specifically, as shown below, a titanium oxide layer, a silicon oxide layer, a first tin oxide layer not doped with fluorine, and a second tin oxide layer doped with fluorine (as shown below) A transparent conductive substrate for a solar cell in which these five layers were laminated on a glass substrate was obtained.

First, it heated at 550 degreeC in the heating zone, conveying a glass base | substrate.
Next, vaporized tetraisopropoxy titanium serving as a raw material for the titanium oxide layer and nitrogen gas as a carrier gas are sprayed onto the heated substrate by a first injector, and titanium oxide is applied to the surface of the substrate being conveyed. A layer was formed. The thickness of the titanium oxide layer was 12 nm. Tetratitanium isopropoxide was put into a bubbler tank kept at about 100 ° C., bubbled with nitrogen gas, vaporized, and transported to an injector through a stainless steel pipe.

  Next, after heating again to 550 ° C. on the substrate having the titanium oxide layer formed on the surface, the second injector sprays silane gas, oxygen gas, and nitrogen gas as the carrier gas as the raw material of the silicon oxide layer. A silicon oxide layer was formed on the surface of the titanium oxide layer of the substrate being conveyed. The film thickness of the silicon oxide layer was 30 nm.

  Further, after heating the substrate having the silicon oxide layer formed on the surface to 540 ° C. again, the third injector uses tin tetrachloride as a raw material for the first tin oxide layer, water, and nitrogen gas as a carrier gas. And a first tin oxide layer not doped with fluorine was formed on the surface of the silicon oxide layer of the substrate being conveyed. Tin tetrachloride was put in a bubbler tank kept at about 55 ° C., bubbled with nitrogen gas, vaporized, and transported to an injector through a stainless steel pipe. Moreover, water transported the water vapor | steam obtained by boiling to another injector by another stainless steel piping.

  Further, after the substrate having the first tin oxide layer formed on the surface is heated again to 540 ° C., the fourth and fifth injectors use tin tetrachloride and water as raw materials for the second tin oxide layer. Hydrogen fluoride and nitrogen gas as a carrier gas were sprayed to form a second tin oxide layer doped with fluorine on the surface of the first tin oxide layer of the substrate being conveyed. In addition, tin tetrachloride and water were transported to the injector by the same method as in the case of the first tin oxide layer. Moreover, hydrogen fluoride transported the vaporized hydrogen fluoride to the injector with the stainless steel pipe, and was supplied on the 1st tin oxide layer in the state mixed with the tin tetrachloride.

The mixing ratio of tin tetrachloride and water was H ₂ O / SnCl ₄ = 80 in terms of molar ratio in both the first tin oxide layer and the second tin oxide layer. The thickness was the same for both the first tin oxide layer and the second tin oxide layer.
Further, the amount of hydrogen fluoride added in the second tin oxide layer was HF / SnCl ₄ = 0.4 in terms of the molar ratio of tin tetrachloride and hydrogen fluoride gas, both of which are raw materials sprayed from the injector.

2. Physical property evaluation About the transparent conductive substrate for solar cells obtained above, the physical property was evaluated as follows.

(1) Mobility When measuring mobility, in the on-line CVD, when forming the second tin oxide layer, HF / SnCl ₄ is a molar ratio of tin tetrachloride as a raw material sprayed from an injector to hydrogen fluoride gas. Various samples were prepared by varying from 1.0 to 2.6. In the off-line _CVD, to create a variety of samples varied from HF / SnCl 4 = 0~2.25.

(A) Mobility measurement method The mobility and carrier concentration of carrier electrons in the fluorine-doped tin oxide layer are measured using the Van der Pauw method by cutting the sample into 1 cm x 1 cm and using HL5500 manufactured by BioRad. I asked for it.
(B) Method for measuring film thickness The film thickness necessary for calculating the mobility was measured with a stylus type surface shape measuring device DEKTAK150 manufactured by Veeco.

The mobility of carrier electrons, the carrier concentration, and the specific resistance are shown in graphs in FIGS.
From FIGS. 5-7, since the fluorine dope tin oxide layer in the sample manufactured by the off-line CVD method increases the carrier concentration as the mobility decreases and the amount of hydrogen fluoride (HF) increases, It had a minimum value in the vicinity of HF / SnCl ₄ = 1.00 to 2.00, and the specific resistance could not be made 4.7 × 10 ⁻⁴ Ω · cm or less. The minimum value of the specific resistance in the off-line CVD was 4.89 × 10 ⁻⁴ Ω · cm when HF / SnCl ₄ = 1.00.

On the other hand, the fluorine-doped tin oxide layer in the sample manufactured by online CVD does not decrease the mobility and increases the carrier concentration even when the amount of hydrogen fluoride (HF) added is increased. 7 × 10 ⁻⁴ Ω · cm or less could be achieved.

5-7, among samples manufactured by online CVD, those having a specific resistance of 4.7 × 10 ⁻⁴ Ω · cm or less and a carrier concentration of 2.5 × 10 ²⁰ cm ⁻³ or more Are examples of the present invention, and other samples and samples produced by off-line CVD are comparative examples.

Thus, according to the embodiment of the present invention, the specific resistance of the fluorine-doped tin oxide layer can be kept low by forming the fluorine-doped tin oxide layer by online CVD under predetermined conditions. A low-resistance fluorine-doped tin oxide layer having a resistance of 7 × 10 ⁻⁴ Ω · cm or less can be obtained. This is because, as in this example, by laminating the thin film while controlling the temperature drop K1 of the glass ribbon within a desired range, the crystallinity of the formed thin film was improved and the mobility was increased, It can be considered that the contribution ratio (doping efficiency) of doped fluorine as a carrier is improved and the carrier density is improved.

(2) C light source haze ratio When measuring the C light source haze ratio, in the on-line CVD, H ₂ O / SnCl ₄ = 40 and HF / SnCl ₄ = 1 are fixed when forming the second tin oxide layer. As it is, tin oxide layers having various film thicknesses were prepared by variously changing the SnCl ₄ concentration. Further, in the off-line CVD, tin oxide layers having various thicknesses were formed by changing the SnCl ₄ concentration while fixing H ₂ O / SnCl ₄ = 80 and HF / SnCl ₄ = 0.4.
Among them, the C light haze ratio was measured at a film thickness of 560 nm, 600 nm, and 730 nm obtained by adding the first tin oxide layer and the second tin oxide layer.

  About the sample for a measurement cut out from the transparent conductive substrate for solar cells, C light source haze rate was measured using the haze meter (HZ-2 type, Suga Test Instruments company make). The results are shown in Table 3. In addition, the numerical value of Table 3 is an average value of 1-3 measurement samples. Here, the C light source is standard light defined by the International Commission on Illumination (CIE). This is used when an object color illuminated with daylight that approximates a color temperature of 6774k is displayed. The haze ratio is a value expressed as a percentage, expressed as an equation (Td−Tn) / Td, where Td is the diffuse transmittance and Tn is the vertical transmittance. Since the haze ratio of the entire surface of the substrate is almost uniform visually, a representative location on the substrate is selected and cut out to obtain a measurement sample.

  From Table 3, it was found that the tin oxide layer in the sample manufactured by online CVD had a higher haze ratio and excellent light scattering properties than the tin oxide layer in the sample manufactured by offline CVD. In particular, the tin oxide layer formed by online CVD had a haze ratio of 10% or more at a wavelength of 550 nm at a thickness of 600 nm and a haze ratio of 550 nm at a thickness of 730 nm was 15% or more.

  As described above, the fluorine-doped tin oxide layer of the float glass with a laminated film manufactured by the CVD method is compared with the fluorine-doped tin oxide layer of the float glass with a laminated film manufactured by the conventional offline CVD method. It was found that the specific resistance was low, the electrical conductivity was excellent, the haze ratio was high, and the light scattering property was excellent. From these facts, it was confirmed that an oxide film with good crystallinity, in other words, a dense oxide film, can be formed by a so-called online CVD method in which a laminated film is formed in a slow cooling furnace.

The present invention is not limited to the embodiment described above, and can be implemented in various forms without departing from the gist of the present invention.
For example, you may apply to the board | substrate of not only the transparent conductive substrate for solar cells but another use.

DESCRIPTION OF SYMBOLS 10 Transparent conductive substrate 13 for solar cells Laminated film 50 Glass manufacturing apparatus 51 Melting furnace 52 Float bath 54 Slow cooling furnace 56 Electric heater 60 Injector 70 Glass ribbon

Claims (8)

Manufactured using a glass manufacturing apparatus comprising a melting furnace for melting glass raw materials, a float bath for floating glass on a molten metal to form a glass ribbon, and a slow cooling furnace for gradually cooling the glass ribbon. A float glass with a laminated film,
The laminated film is formed on the glass ribbon by a plurality of injectors provided in the slow cooling furnace by a CVD method,
The laminated film is formed at Tg + 50 ° C. or lower when the glass transition temperature is Tg and the glass strain temperature is Ts, and at least two layers of the laminated film are formed in a temperature range of Tg + 50 ° C. to Ts. And
The temperature drop K1 per unit length of the glass ribbon in the temperature region for forming all the layers of the laminated film is 0 ° C./m<K1<10° C./m,
The laminated film includes a fluorine-doped tin oxide layer,
The fluorine-doped tin oxide layer has a laminated film characterized by having a specific resistance of 4.7 × 10 ⁻⁴ Ω · cm or less and a carrier concentration of 2.5 × 10 ²⁰ cm ⁻³ or more. Float glass. The float glass with a laminated film according to claim 1, wherein the laminated film has a mobility of 45 cm ² / V · s or more.   The float glass with a laminated film according to claim 1, wherein at least two layers of the laminated film are formed in a temperature range of Tg + 50 ° C. to Tg.   The said laminated film contains a silicon oxide layer, The float glass with a laminated film of any one of Claims 1-3 characterized by the above-mentioned.   The float glass with a laminate film according to any one of claims 1 to 4, wherein the laminate film further includes a tin oxide layer that is not fluorine-doped.   6. The laminate according to claim 5, wherein the tin oxide layer composed of the fluorine-doped tin oxide layer and the non-fluorine-doped tin oxide layer has a haze ratio of 10% or more at a wavelength of 550 nm at a thickness of 600 nm. Float glass with membrane.   6. The laminate according to claim 5, wherein the tin oxide layer comprising the fluorine-doped tin oxide layer and the non-fluorine-doped tin oxide layer has a haze ratio of 15% or more at a wavelength of 550 nm at a thickness of 730 nm. Float glass with membrane. A CVD method using a glass manufacturing apparatus comprising a melting furnace for melting glass raw materials, a float bath for floating glass on a molten metal to form a glass ribbon, and a slow cooling furnace for gradually cooling the glass ribbon A method for producing a laminated film-attached glass substrate by forming a laminated film on the glass ribbon with a plurality of injectors provided in the slow cooling furnace, and cutting the glass ribbon,
When the glass transition temperature is Tg and the glass strain temperature is Ts, the laminated film is formed at Tg + 50 ° C. or lower, and at least two layers of the laminated film are formed at a temperature range of Tg + 50 ° C. to Ts. ,
The temperature drop K1 per unit length of the glass ribbon in the temperature region for forming all the layers of the laminated film is 0 ° C./m<K1<10° C./m,
The laminated film includes a fluorine-doped tin oxide layer having a specific resistance of 4.7 × 10 ⁻⁴ Ω · cm or less, tin tetrachloride and hydrogen fluoride gas are in a molar ratio, and HF / SnCl ₄ = 1.0. A method for producing a glass substrate with a laminated film, wherein the fluorine-doped tin oxide layer is formed by spraying a raw material gas so as to be larger than that.

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