JP2001015783A - Method and device for manufacturing tin oxide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make uniform film thickness or the like, without being affected by fluctuations in wind and air pressure around a device by mixing gas containing tin tetrachloride and gas containing water in advance and discharging the obtained gas essentially containing the tin tetrachloride and water by turbulence, and forming a tin oxide film on a glass substrate. SOLUTION: A gas containing tin tetrachloride and water is discharged onto a glass substrate that travels in one direction essentially by turbulence, and a tin oxide film is formed by the reaction with tin tetrachloride enriched water occurring on a high-temperature glass substrate. In this manner, since turbulent gas is used for manufacturing the tin oxide film, air current balance cannot be lost even if wind and air pressure around the device fluctuate, thus obtaining a tin oxide film with a uniform film thickness and crystal particle diameter. More specifically, when the flow of gas is a laminar flow, eddies or the like are generated due to the influence of fluctuation factors and the tin oxide film tends to become nonuniform. However, when it is a turbulent flow, the influence is suppressed. In this manner, the obtained tin oxide film is uniform to the extent that it can be used as an electrode for a solar battery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a tin oxide film, and more particularly, to a method for producing a tin oxide transparent conductive film suitably used as a transparent conductive film for a solar cell substrate. Further, the present invention relates to an apparatus for producing a tin oxide film used in the production method.

[0002]

2. Description of the Related Art As a method of forming a tin oxide film, a method of forming a tin oxide film by a CVD method utilizing a reaction between tin tetrachloride and water is known. In this method, tin tetrachloride vapor is brought into contact with a heated substrate surface in an oxidizing atmosphere,
A tin oxide film is formed on the substrate surface by a thermal decomposition / oxidation reaction on the substrate surface. For example, Japanese Patent Application Laid-Open No. 55-15995 discloses that a gaseous medium containing tin tetrachloride and water vapor is brought into contact with a surface of a glass substrate or the like at a predetermined temperature to perform a chemical reaction and / or
Alternatively, a method of forming a tin oxide coating by decomposition is described. In this method, tin tetrachloride and steam are supplied to the coating area in separate gas streams to avoid depositing solids inside the steam supply channel due to the early reaction of the tin salt, and the vicinity of the substrate surface to be coated. To make them react with each other. Also, the gaseous medium flows along a substrate surface which is partly defined by the glass surface and is coated as a substantially undisturbed layer along a flow path leading to the exhaust duct, in other words laminar flow. It is stated that it is necessary. But,
In the above method, when a gas flow containing tin tetrachloride and a gas flow containing water vapor meet near the substrate surface, they are mixed unevenly, so that the tin oxide film is not uniform. Further, the above method also has a disadvantage that the yield of the tin oxide film is low with respect to the dose of tin tetrachloride.

Japanese Patent No. 2,833,797 discloses that a flow of a first reaction gas composed of tin tetrachloride is formed along a glass surface, and a flow of water vapor composed of 20% hydrofluoric acid is formed in the flow. Introducing a turbulent flow of the second reaction gas,
A method for depositing a tin oxide coating by means of a combined turbulent flow is described. And, in the specification, by giving the second reaction gas as a turbulent flow, mixed with a sufficient degree of mixing with the first flow already in contact with the glass,
It is described that a sufficiently uniform layer can be deposited. However, in the above method, since the tin tetrachloride and water are separately supplied and mixed on the substrate, actually, the mixing of the first stream and the second stream is not sufficient, and the obtained tin oxide film is obtained. Cannot be said to have sufficiently uniform electrical and optical characteristics. In particular, it does not satisfy a high level of uniformity of electrical and optical characteristics required for a tin oxide transparent conductive film used as a transparent conductive film for a solar cell substrate.

[0004] Further, Japanese Patent Application Laid-Open No. 9-40442 discloses that tin tetrachloride and water are separated from each other at 100 to 240 ° C.
A method is described in which a single stream is provided at a temperature in the range of 1 to form a single stream and the single stream is directed onto the glass of the substrate in a substantially laminar flow to form a coating. In the above method, since tin tetrachloride and water are mixed in advance, there is a problem that the method described in the above-mentioned Japanese Patent Application Laid-Open No. 55-15959 and the method described in Japanese Patent No. 2833797 have a problem. Is resolved. Japanese Patent Application Laid-Open No. 9-40442 discloses that when tin tetrachloride and water vapor are supplied in separate gas flows that meet only on the surface of the glass, the gas flow along such a surface becomes turbulent, and the coating is performed. Is inefficient, while the length of the passage through which the premixed gas passes is important in this invention, and the length of the passage is such that the premixed gas can be balanced to become laminar. It is also described to be as short as possible and impinge a single gas stream on the substrate in substantially laminar flow. However, a method for producing a tin oxide film by using a gas flow containing tin tetrachloride and water in a laminar flow has the following problems. First, airflow balance tends to be out of order due to slight fluctuations in wind and pressure around the device, resulting in non-uniform film thickness and crystal grain size. Second, it is technically difficult to create a laminar flow that is uniform in the flow direction and uniform in a direction perpendicular to the flow direction. The generation of streak-like uneven portions in the direction. Third, in a case where the glass substrates cut to a predetermined size are arranged in a line and a tin oxide film is formed by continuously passing under the injector, the gas flows in the gap between the glass plates. Is disturbed, so that the film thickness or the like becomes non-uniform in the vicinity of the end portion (the portion in contact with the gap) of the glass plate. Due to these problems, the yield during operation has remained at a low level of about 80 to 85%.

Therefore, a method of forming a tin oxide film by a CVD method utilizing a reaction between tin tetrachloride and water,
A method suitable for forming a tin oxide film on a glass substrate cut to a predetermined size without being affected by wind and atmospheric pressure fluctuations around the apparatus, which can make the film thickness uniform, is desired. I was

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method for forming a tin oxide film by a CVD method utilizing the reaction between tin tetrachloride and water. It is an object of the present invention to provide a method suitable for forming a tin oxide film on a glass substrate cut to a predetermined size, and a device used therefor, which can make the film thickness and the like uniform. .

[0007]

SUMMARY OF THE INVENTION The present invention is a method for producing a tin oxide film by forming a tin oxide film on a glass substrate moving in one direction by reacting tin tetrachloride and water by a CVD method. A gas containing tin tetrachloride and a gas containing water are mixed in advance, and the resulting gas containing tin tetrachloride and water is discharged in a substantially turbulent flow to form a tin oxide film on a glass substrate. Provided is a method for manufacturing a tin oxide film, which is characterized by being formed.

Further, the present invention provides a method of forming a tin oxide film on a glass substrate moving in one direction by reacting tin tetrachloride with water.
An apparatus for producing a tin oxide film formed by a method, wherein a gas containing tin tetrachloride and water obtained by previously mixing a gas containing tin tetrachloride and a gas containing water is substantially disturbed. Provided is an apparatus for manufacturing a tin oxide film including an injector that discharges by a flow.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A method for producing a tin oxide film according to the present invention comprises:
A method for producing a tin oxide film by forming a tin oxide film on a glass substrate moving in one direction by reacting tin tetrachloride and water, the method including a gas and water containing tin tetrachloride in advance. And a gas containing tin tetrachloride and water thus obtained is discharged in a substantially turbulent flow to form a tin oxide film on a glass substrate. The gas containing tin tetrachloride and water (steam) used in the present invention is obtained by mixing a gas containing tin tetrachloride and a gas containing water. In the present invention, a gas containing tin tetrachloride and a gas containing water are mixed in advance, and the obtained gas containing tin tetrachloride and water is used for forming a tin oxide film. There is no problem that the electrical and optical characteristics of the obtained tin oxide film become non-uniform as in the case of mixing on a glass substrate.

As the gas containing tin tetrachloride, for example, an inert gas (a gas that does not react with tin tetrachloride), preferably nitrogen, is blown into liquid tin tetrachloride in a bubbler tank to vaporize the tin tetrachloride. Obtainable. When the gas containing tin tetrachloride contains an inert gas such as nitrogen, the reaction between tin tetrachloride and water is less likely to occur, which is a preferred embodiment. The gas containing water includes, for example, a gas containing only steam and a gas containing air containing steam.

The gas containing tin tetrachloride and the gas containing water are mixed and maintained preferably at a temperature in the range of 100 to 240 ° C. When the gas after mixing is maintained in the above temperature range, the reaction between tin tetrachloride and water is suppressed, and no or little reaction occurs. More preferably, the temperature is in the range of 130 to 170C.

When the gas containing tin tetrachloride and the gas containing water are mixed, the gas becomes a uniform gas due to the diffusion phenomenon of gas molecules. However, the gas may be stirred by a gas mixer or the like.

The proportion of tin tetrachloride and water in the gas containing tin tetrachloride and water is preferably 50 mol or less per 1 mol of tin tetrachloride. In the above range,
The reaction between tin tetrachloride and water in a mixed state is suppressed. The ratio is more preferably 30 mol or less, particularly preferably 20 mol or less, based on 1 mol of tin tetrachloride.

The gas containing tin tetrachloride and water can contain other substances as long as the object of the present invention is not impaired. For example, it may contain hydrogen chloride; a fluorine compound such as hydrogen fluoride and trifluoroacetic acid; a lower alcohol such as methanol and ethanol; and an inert gas such as nitrogen. When the gas containing tin tetrachloride and water contains hydrogen chloride, the reaction between tin tetrachloride and water is less likely to occur, which is a preferred embodiment. When at least one of the gas containing tin tetrachloride and the gas containing water contains hydrogen chloride, the mixture of the two is preferably 45%.
It is performed at a temperature of 0 ° C. or less. The content of hydrogen chloride is preferably at least 1 mol per mol of tin tetrachloride, more preferably 3 to 5 mol. Further, when the gas containing tin tetrachloride and water contains a fluorine compound, the conductivity is high, which is a preferable embodiment. In this case, when a lower alcohol is further contained, fluorine doping is promoted.

The present invention is a method for forming a tin oxide film on a glass substrate by a CVD method by discharging a gas containing tin tetrachloride and water substantially in a turbulent flow. Specifically, the gas containing tin tetrachloride and water is discharged in a substantially turbulent flow onto the glass substrate moving in one direction, and the reaction between tin tetrachloride and water occurs on the high-temperature glass substrate. Then, a tin oxide film is formed.

The glass used in the present invention is not particularly limited. For example, oxide glass can be used. Examples of the oxide glass include silicate glass, phosphate glass, and borate glass. Examples of the silicate glass include soda lime glass, silicate glass, alkali silicate glass, potassium lime glass, lead (alkali) glass, borosilicate glass, and aluminosilicate glass.

Further, after forming at least one thin film on a glass substrate by sputtering, vacuum deposition, or the like, a tin oxide film can be formed on the thin film according to the present invention to form a multilayer film. Examples of such a thin film include thin films of metals, alloys, oxides, nitrides, and carbides thereof. Specifically, when soda-lime glass is used as a substrate, a silica (SiO ₂ ) film or the like is formed as an undercoat (hereinafter, referred to as an “alkali barrier layer”) for preventing diffusion of an alkali component from the substrate. Can be used.

The shape and size of the glass substrate are not particularly limited, and may be, for example, a plate having a thickness of 0.2 to 5 mm. The plate-like glass substrate has a width of 10 to 500 c.
m, and may be cut to an appropriate length, or may be in an uncut state (ribbon shape). The geometric thickness (hereinafter, simply referred to as “film thickness”) of the alkali barrier layer can be, for example, 2 to 100 nm. The temperature of the glass substrate is 450-620 ° C
It is preferred that This is because the reaction between tin tetrachloride and water sufficiently occurs within the above range, and the film formation rate is high. The temperature of the glass substrate is more preferably 500 to 600C.

The CVD method is preferably performed at normal pressure (atmospheric pressure).

In the present invention, a turbulent flow refers to a flow including irregular fluctuations in time and space, that is, turbulence. Turbulent flow is obtained by transitioning from an unstable laminar flow when the Reynolds number represented by the following equation is about 2,000 or more when a gas flows in a circular pipe. Re = uL / ν (where, Re: Reynolds number, u: representative velocity of gas,
L: representative length (diameter) of a circular tube, ν: kinematic viscosity (= viscosity /
density))

Conventionally, in a method of forming a tin oxide film by a CVD method utilizing a reaction between tin tetrachloride and water, it has been considered that a gas flow to be brought into contact with a substrate is preferably a laminar flow. . JP-A-55-15995 discloses that
It is stated that the gas flow is preferably laminar. Japanese Patent Application Laid-Open No. 9-40442 discloses that if the gas flow is laminar, there is no problem that the coating becomes inefficient if the gas flow is turbulent. Is set to 10 cm or more, and it is described that the gas can be made into a laminar flow.

Surprisingly, however, it has been found that very good results can be obtained if the gas obtained by mixing the gas containing tin tetrachloride and the gas containing water is discharged in a substantially turbulent flow. Do you get it. That is, in the present invention, since a turbulent gas is used for producing the tin oxide film, the following advantages are obtained.

First, even if the wind or air pressure around the apparatus fluctuates, the air flow balance is hardly disrupted, and a tin oxide film having a uniform thickness and crystal grain size can be obtained. That is, if the gas flow is laminar, eddies and the like are likely to be generated due to the influence of fluctuation factors, and the tin oxide film is likely to be non-uniform. However, if the flow is turbulent, the effect is suppressed. In particular, a tin oxide film used as a solar cell substrate needs to form a uniform uneven shape on its surface in order to increase energy conversion efficiency.
Although a high level of uniformity such as film thickness is required, the tin oxide film obtained by the present invention can be used as a transparent conductive film (solar cell electrode) formed in contact with silicon or the like of a solar cell. To the extent uniform.

Second, the flow direction and / or
Or, a streak-like non-uniform portion in a direction perpendicular to the direction does not occur.

Third, in a case where the glass substrates cut to a predetermined size are arranged in a row and continuously passed under the injector to form a tin oxide film, a gap between the glass plates is required. The gas flow is temporarily disturbed. Immediately after that, the components of the gas are quickly homogenized by turbulent diffusion, so that the film thickness or the like is not good near the edge of the glass plate (portion where the gap is formed). There is no uniformity.

Because of these advantages, operating yields can be as high as 90% or more.

As described above, the turbulent flow used in the present invention means a flow including irregular fluctuations in time and space immediately before the gas flow comes into contact with the glass substrate. There is a flow component in the direction of, for example,
This is a state where a vortex is formed when viewed locally. Such a turbulent flow may be a high Reynolds number flow or a slightly lower Reynolds number, but the sudden direction of the gas flow in the gap between the glass plates cut to a predetermined size. The turbulence must be sufficient to minimize the effects of turbulence with abruptness and sudden directional turbulence due to airflow balance and temperature. That is,
It was thought that the gas flow needed to be laminar, but the present inventor said that if turbulent, the influence of the fluctuation factors that are a problem in the case of laminar flow would be eliminated. This led to the present invention. Therefore, the turbulence used in the present invention has a Reynolds number of 2000 to 400.
When the Reynolds number is 2,000 or less, it can be obtained by giving a perturbation such as shear to the upstream side of the flow to cause turbulence. In the present invention, it is preferable to obtain the Reynolds number by setting the Reynolds number to 2000 or less and causing a perturbation such as shearing on the upstream side of the flow to cause turbulence. Since finer turbulence occurs than the turbulence obtained by setting the Reynolds number to 2000 or more, the film is hardly affected by external influences, and the uniformity of the electrical and optical characteristics of the film is sufficient. Because it becomes.

In the present invention, discharging a gas containing tin tetrachloride and water substantially in a turbulent flow means that the state immediately after being discharged from the discharge port is substantially a turbulent flow. In the present invention, since the flow of the gas containing tin tetrachloride and water is already turbulent when discharged from the discharge port, the influence of sudden directional turbulence due to airflow balance and temperature. And thus the resulting film is less susceptible to them. In this point, it is different from the prior art in which the gas is mixed on the substrate to make it turbulent.

JP-A-61-586 discloses a liquid coating composition comprising an organic fluorine dopant compound and tin tetrachloride.
A method is described for producing coatings by means of said vapor in an oxygen-containing atmosphere, which evaporates at a temperature of from 400C to 400C and may not be turbulent. Further, in the above-mentioned publication, a film without fogging is desired, and it is apparent that the use as a transparent conductive film for a solar cell substrate, which needs to be a film with haze, is not intended. However, the method disclosed in the above publication cannot realize the uniformity of the film thickness and the like required for the transparent conductive film for a solar cell substrate.

The thickness (maximum thickness) of the tin oxide film obtained according to the present invention is not particularly limited and can be adjusted according to the application. However, when the tin oxide film is used as a transparent conductive film for a solar cell substrate (electrode for a solar cell). Is preferably 400 to 1000 nm, more preferably 600 to 800 nm. Thickness (maximum thickness) of tin oxide film obtained by the present invention
Is -15 to + 15%, particularly -10 to + 10%
It is preferred that Further, the tin oxide film obtained by the present invention has a shape having irregularities uniformly over the entire surface, and the height of the projection is about 100 to 200 nm.

The sheet resistance of the tin oxide film obtained according to the present invention is not particularly limited and can be adjusted according to the use.
When used as a transparent conductive film for a solar cell substrate, 5 to 5
It is preferably 15 Ω / □, more preferably 5 to 10 Ω / □.

The visible light transmittance (hereinafter simply referred to as “transmittance”) of the tin oxide film obtained according to the present invention is not particularly limited and can be adjusted according to the application. However, when the tin oxide film is used as a transparent conductive film for a solar cell substrate. Is preferably 80 to 95%, more preferably 85 to 95%.

The haze ratio of the tin oxide film obtained according to the present invention is not particularly limited, and can be adjusted according to the intended use.
It is preferably 30% to 30%, more preferably 10% to 15% on average. Further, the fluctuation range of the haze ratio is preferably −20 to + 20%, more preferably −10 to + 10%, with respect to the average value of the haze ratio.

The use of the tin oxide film obtained by the present invention is not particularly limited. However, the tin oxide film has both high transmittance and high conductivity in the visible light region and is excellent in uniformity such as film thickness. For example, an electrode for a solar cell; a transparent electrode for a liquid crystal display, an EL display, a plasma display, a touch panel, etc .; a heat ray reflective film for automobiles and buildings; an antistatic film for photomasks and other various applications;
It can be used as an electromagnetic shielding film on the T surface; a transparent heating element for various types of antifogging such as for a freezing showcase; and an electrode for an electrochromic element as a light control glass.

The apparatus for producing a tin oxide film of the present invention is an apparatus for producing a tin oxide film on a glass substrate which moves in one direction by reacting tin tetrachloride and water by a CVD method. The gas containing tin tetrachloride and water discharged from the injector, which is obtained by mixing a gas containing tin tetrachloride and a gas containing water in advance, is substantially turbulent. is there. Hereinafter, a specific description will be given with reference to FIG.

FIG. 1 is a conceptual diagram showing an example of the apparatus for producing a tin oxide film of the present invention. Note that the manufacturing apparatus of the present invention is not limited to this. First, the configuration of the apparatus for manufacturing a tin oxide film will be described. The apparatus for producing a tin oxide film of the present invention is provided with an injector main body 1 to which a gas containing vaporized tin tetrachloride and a gas containing water are supplied, and the two are mixed in advance.
An injector discharge section 2 for discharging the mixed gas substantially in a turbulent flow. The injector body 1 is provided with a jacket 5 for passing a heat medium (oil or the like) therein to keep the injector body 1 at a constant temperature, and the injector discharge unit 2 passes a heat medium (oil or the like) inside to discharge the injector. A jacket 6 is provided for keeping the part 2 at a constant temperature.

The injector body 1 has a conduit 3 for supplying a gas containing tin tetrachloride from a bubbler tank. In the bubbler tank, an inert gas such as nitrogen is blown into the liquid tin tetrachloride from a cylinder, and the tin tetrachloride is vaporized to generate a gas containing tin tetrachloride. The bubbler tank is kept at 20 to 100C. The gas containing tin tetrachloride should be 130-130 before mixing with the gas containing water.
It is heated to 170 ° C. and supplied to the injector body 1.

The injector body 1 has a conduit 4 for supplying vaporized water (steam) from the boiler.
The boiler supplying water is kept at 100 ° C. or higher.
The gas containing water is heated to 130 to 170 ° C. before being mixed with the gas containing tin tetrachloride and supplied to the injector body 1.

In the injector body 1, a gas containing tin tetrachloride supplied from the bubbler tank via the conduit 3 and a gas containing water supplied from the boiler via the conduit 4 are mixed. The internal temperature of the injector body 1 is maintained at 130 to 170 ° C. by passing a heat medium (oil or the like) through the jacket 5.

The injector discharge section 2 discharges the gas mixed in the injector body 1 substantially in a turbulent flow. The shape and size of the injector discharge unit 2 are not particularly limited as long as the gas can be discharged substantially in a turbulent flow.
(A)), an intermediate portion of a discharge portion is branched into two portions, and each outlet has a shape facing the discharge port (FIG. 2
(B)) a device having a net at the discharge port for discharging gas through the net, and a representative length (diameter) of a circular tube according to the representative speed and kinematic viscosity of the gas so that the Reynolds number becomes 2000 or more. ), Those in which the injector discharge section 2 has a tapered constriction, and those in which the distance from the injector body 1 to the tip of the injector discharge section 2 is sufficiently short to discharge a turbulent flow are used. Can be. The gas containing tin tetrachloride and water discharged from these injector discharge parts 2 is substantially turbulent. That is, the state immediately after the gas containing tin tetrachloride and water is discharged from the discharge port is substantially turbulent. The internal temperature of the injector discharge section 2 is maintained at 130 to 170 ° C. by passing a heat medium (oil or the like) through the jacket 6.

The gas containing tin tetrachloride and water is discharged from the injector discharge section 2 to the glass substrate 7.
The distance between the tip of the injector discharge section 2 and the surface of the glass substrate is preferably 1 to 3 cm. The discharge angle is
The angle is preferably 45 to 90 degrees with respect to the surface of the glass substrate (the moving direction of the glass substrate is 0 degree).

The discharge amount of the gas containing tin tetrachloride and water is 0.07 to ⁷ m ³ / m per 1 m of the width of the glass substrate.
It is preferably in. The discharge speed of the gas containing tin tetrachloride and water is preferably 0.5 to 7 m / s.

The moving speed of the glass substrate depends on the discharge amount of the gas containing tin tetrachloride and water. For example, when the discharge amount per 1 m of the width of the glass substrate is 0.1 m ³ / min, , And 0.5 to 1.5 m / s.

The apparatus for producing a tin oxide film of the present invention is an example of an apparatus most suitable for implementing the method for producing a tin oxide film of the present invention.
In the apparatus for producing a tin oxide film according to the present invention, the shape of the injector for creating a turbulent flow can be designed more freely than the shape for producing a laminar flow, and is not limited to the shape exemplified above. In addition, when a laminar flow is to be generated, the discharge speed of the gas needs to be reduced to some extent, whereas when a turbulent flow is to be generated, the discharge speed can be increased. Therefore, by forming the injector in a shape such that tin oxide does not easily adhere thereto or by increasing the distance between the glass substrate and the tip of the injector discharge section, it is possible to prevent the generation of deposits of tin oxide. Thus, continuous production of the tin oxide film becomes possible, and the production cost can be reduced.

[0045]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. 1. Production of Tin Oxide Film (Example 1) A soda lime glass substrate (5) on which a silica film having a thickness of about 50 nm was formed as an alkali barrier layer
(0 cm × 100 cm × 3 mm), and after sufficient cleaning, using a tin oxide film manufacturing apparatus of the present invention shown in FIG. A tin oxide transparent conductive film was formed by the reaction. Specifically, the procedure was as follows. Tin tetrachloride was put into a bubbler tank maintained at 55 ° C., and nitrogen was introduced from a cylinder to evaporate. Water was supplied from a boiler maintained at 100 ° C. or higher. After heating both to 150 ° C,
Was transported to the injector body 1 via the conduits 3 and 4 kept warm, and mixed. The mixing ratio (mol ratio) was tin tetrachloride: water = 1: 20. The temperature of the injector body 1 was maintained at about 150 ° C. by a heating medium (oil). The mixed gas was discharged from the injector discharge unit 2 onto the glass substrate 7 at about 500 ° C., to form a tin oxide transparent conductive film on the surface of the glass substrate. As the injector discharge section 2, one having an uneven inner wall (FIG. 2A) was used. The gas containing tin tetrachloride and water had a Reynolds number of 1500 due to the unevenness of the inner wall of the injector discharge section 2,
Discharge was substantially turbulent over the entire width direction of the injector (the direction orthogonal to the direction in which the glass substrate moves). The glass substrate is a rectangular plate 2
The sheets of glass were flowed at an interval of 2 cm, and the influence of the edge passing under the injector was also observed. Also, C
Vary the room pressure of the clean room communicating with the VD furnace,
The effects were also observed.

(Example 2) The injector discharge section 2 is divided into two in the middle of the discharge section, and each outlet has a shape facing each other near the discharge port (FIG. 2 (b), the inner wall is smooth). A tin oxide transparent conductive film was formed on the surface of the glass substrate in the same manner as in Example 1 except that the above method was used.
The gas containing tin tetrachloride and water is discharged from the discharge port immediately after the two flows coming out of the opposed outlets collide with each other. Therefore, the Reynolds number was 1800, but the width direction of the injector (glass The discharge was substantially turbulent over the entire direction (the direction perpendicular to the direction in which the substrate moves).

Comparative Example 1 A tin oxide transparent conductive film was formed on the surface of a glass substrate in the same manner as in Example 1 except that an injector discharge section 2 having a smooth inner wall was used. The gas containing tin tetrachloride and water was discharged in a substantially laminar flow over the entire width of the injector.

2. Physical properties of tin oxide transparent conductive film The following physical properties of the obtained tin oxide transparent conductive film were measured and evaluated. The results are shown in Table 1. (1) Film thickness The film thickness (maximum film thickness) was measured using a stylus-type surface roughness meter. The film of Example 1 was 400 nm, and the film of Example 2 was 60 nm.
0 nm, and the film of Comparative Example 1 had a thickness of 500 nm. Although the film thicknesses of Examples 1 and 2 were almost uniform at the glass edge, the film thickness of Comparative Example 1 was 1 mm at the glass edge.
There was a portion as thin as about 00 nm. Further, when the room pressure of the clean room communicating with the CVD furnace was varied and the occurrence of film thickness unevenness was observed, in Examples 1 and 2, no film thickness unevenness was observed. Streak-like film thickness unevenness, which is considered to be caused by the fluctuation of the flow of the gas containing tin and water, occurred.

(2) Sheet resistance The sheet resistance was measured by a four-terminal method. A glass substrate having a film on the surface obtained in each of Examples and Comparative Examples was cut into a square of about 3 cm, and a pair of electrodes having a length of 3 cm was placed on two opposing sides so that the distance between the electrodes was 3 cm. Was mounted in parallel. Next, the resistance (sheet resistance) between the electrodes was measured with a tester. The film of Example 1 was 20Ω / □, and the film of Example 2 was
Was 10 Ω / □ and the film of Comparative Example 1 was 15 Ω / □.

(3) Transmittance The average value of the spectral transmittance at a wavelength of 400 nm to 800 nm was measured by a spectrophotometer, and the value was defined as the transmittance. 86% for the film of Example 1, 88% for the film of Example 2, and 8% for the film of Comparative Example 1.
7%.

(4) Haze unevenness and haze ratio Haze unevenness was visually observed. Further, at 10 locations distributed over the entire surface of the substrate, the wavelength is 400 nm to 800 nm.
Was measured with a haze meter. In the film of Example 1, uneven haze was not observed on the entire surface of the substrate.
The haze rate was 8% on average, 10% in the high part and 6% in the low part. In the film of Example 2, haze unevenness was not observed on the entire surface of the substrate, and the haze ratio was 10% on average, 12% in high portions and 8% in low portions.
The films of Examples 1 and 2 were suitable as transparent conductive films for solar cell substrates. The film of Comparative Example 1 was formed on the entire surface of the substrate.
Haze unevenness of a striped pattern considered to be caused by the turbulence of the gas flow at the end was observed, and the haze ratio was 9% on average, 18% in a high portion, and 5% in a low portion. The film of Comparative Example 1 was not suitable as a transparent conductive film for a solar cell substrate.

3. Yield during operation Yield when the production of the tin oxide film was performed for 7 consecutive days was determined. The yield was determined by dividing the value obtained by subtracting the number of loss pieces from the number of supplied glass pieces by the number of supplied glass pieces. The number of loss pieces is a glass substrate having a streak-like film thickness unevenness, a glass substrate having a haze unevenness such that the haze ratio becomes a difference of 2 points or more with respect to the average, and a glass having an inevitable loss in production. The total number of substrates was used. The yield was 97% in Example 1, 95% in Example 2, and 85% in Comparative Example 1.

[0053]

[Table 1]

[0054]

According to the method for producing a tin oxide film of the present invention,
The thickness and the like of the obtained tin oxide film can be made uniform without being affected by wind and pressure fluctuation around the apparatus. The method for producing a tin oxide film of the present invention is also suitable for forming a tin oxide film on a glass substrate cut to a predetermined size. Further, the apparatus for producing a tin oxide film of the present invention is suitably used for performing the above method.

[Brief description of the drawings]

FIG. 1 is a diagram showing an apparatus for producing a tin oxide film of the present invention.

FIGS. 2A and 2B are cross-sectional views showing an example of an injector discharge unit of the apparatus for manufacturing a tin oxide film of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injector main body 2 Injector discharge part 3, 4 Conduit 5, 6 Jacket 7 Glass substrate

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yukio Yoshikawa 1150 Hazawa-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside Asahi Glass Co., Ltd. (72) Inventor Neiji Fukazawa 1150 Hazawa-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture F term (reference) 2H092 HA04 MA07 MA27 NA29 PA01 4G059 AA08 AC12 EA02 EB01 4K030 AA02 BA16 BA45 BB01 BB13 CA06 DA02 DA05 EA05 FA10 HA04 JA10 LA01 LA16 5F051 FA03 FA19 FA24 FA30 GA03 5G323 BA03 BB03

Claims (2)

[Claims] 1. A method for producing a tin oxide film by forming a tin oxide film on a glass substrate moving in one direction by reacting tin tetrachloride and water, the tin oxide film containing tin tetrachloride in advance. Mixing a gas and a gas containing water, and discharging the obtained gas containing tin tetrachloride and water substantially in a turbulent flow to form a tin oxide film on a glass substrate. Manufacturing method of tin film. 2. A tin oxide film manufacturing apparatus for forming a tin oxide film on a glass substrate moving in one direction by reacting tin tetrachloride and water by a CVD method, the tin oxide film containing tin tetrachloride in advance. An apparatus for producing a tin oxide film, comprising an injector for discharging a gas containing tin tetrachloride and water obtained by mixing a gas and a gas containing water in a substantially turbulent flow.