JPH0450683B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for forming a transparent conductive thin film of fluorine-doped tin oxide (SnO ₂ (F)) by a CVD method, and in particular, a method for forming a transparent conductive thin film of fluorine-doped tin oxide (SnO 2 (F)) on the surface of a glass substrate using fluorocarboxylic acid as a fluorine compound. By forming a film, it is possible to obtain a film that has high reflectance in the infrared region, low resistance, good conductivity, and excellent hardness and chemical and mechanical durability. It can be widely adopted in the field of That is, it can be coated on the surface of a glass substrate, for example, on anti-fog window glasses or heat-reflecting transparent window glasses of buildings, automobiles, aircraft, ships, or refrigerated cases, as well as on Cahar glass of solar collectors and door glass of ovens. It can be put to practical use in many fields, such as in parts for electrical and electronic equipment such as liquid crystal electro-optic displays. [Prior art] Conventionally, in the spray method, a tin compound such as (C ₄ H ₉ ) ₂ Sn (CH ₃ CO ₂ ) ₂ and CF ₃ COOH
There is a known method (Japanese Patent Publication No. 53-25331) in which a solution of a fluorine compound such as fluorine compound and a solvent such as CH ₃ OH is sprayed onto a high-temperature plate glass to form a SnO ₂ (F) film. In addition, in the CVD method, for example, tin compound vapor such as (CH ₃ ) ₄ Sn and gaseous fluorine compounds such as CF ₃ Br are sprayed onto hot glass.
Method for forming SnO ₂ (F) film
58363) is known. [Problems to be solved by the invention] In the method described in the aforementioned Japanese Patent Publication No. 53-25331,
A film with low resistance cannot be obtained unless 30% or more of CF ₃ COOH is added to the solution and the temperature of the glass substrate is raised to 600°C or higher, and it is not economical to consume large amounts of expensive chemicals such as CF ₃ COOH. Moreover, if the temperature of the glass substrate is raised to a fairly high temperature of 600℃ or higher, the glass may become distorted or warped, making it difficult to obtain a good product.Furthermore, the infrared reflectance and resistance value are sufficiently satisfactory. A film cannot be obtained, and even if this chemical solution is directly applied to the CVD method, the film formation rate is slow and it is difficult to employ it. On the other hand, in the method described in JP-A-55-58363, as mentioned above, tetramethyltin etc. are used as the tin compound and CF ₃ Br as the fluorine compound.
However, tetramethyltin has a slow film formation rate and is difficult to apply to low resistance, high infrared reflectance coatings on large glass plates, and gaseous fluorine compounds such as CF ₃ Br Although it is an effective compound as a doping agent, it is expensive and has to be consumed in large quantities, making it uneconomical. In addition, it is undesirable to use a large amount for pollution reasons. [Means for Solving the Problems] The present invention has been made in view of the above-mentioned drawbacks of the conventional technology. SnO ₂ is produced by transporting each acid vapor using a carrier gas and blowing out a mixed vapor.
(F) It was discovered that a coating with better resistance and high infrared reflectance can be obtained efficiently by a method of forming a thin film. That is, the present invention provides a method for forming a tin oxide film by ejecting a mixed vapor of a tin compound, which is an organic tin halide, and a fluorine compound onto the surface of a heated glass substrate. is used in a weight ratio of 0.01 to 0.058, and the fluorocarboxylic acid as the fluorine compound is CF ₃ COOH, C ₃ F ₇ COOH, CF ₃ CH
The present invention provides a method for forming the above-mentioned transparent conductive thin film in which =CHCOOH. In the present invention, the temperature of the glass substrate is
The temperature is preferably 500 to 600°C, and the tin compound is an organic tin halide, such as ( _CH3 ) _{2SnCl2 ,}
Compounds such as (C ₄ H ₉ ) SnCl ₃ and (C ₄ H ₉ ) ₂ SnCl ₂ , especially when undercoated with silicon oxide, do not generate haze and the film formation speed is satisfactory. This is preferable. Furthermore, examples of fluorocarboxylic acids include CF ₃ COOH,
Compounds such as C ₃ F ₇ COOH and CF ₃ CH=CHCOOH are used, and the quantitative range of the fluorocarboxylic acid is as follows:
For example, as shown in Examples 1 or 3 to 6,
Regarding CF ₃ COOH, the ratio by weight to (CH ₃ ) ₂ SnCl ₂ is 0.013 to 0.058, preferably
The ratio is between 0.01 and 0.03. Furthermore, the weight ratio is 0.01 to 0.05 with respect to a tin compound which is another organic tin compound. Furthermore, the quantitative range of the other fluorocarboxylic acids is also within the ratio range as shown in Example 2. Further, the carrier gas may be pressure-regulated air, nitrogen gas, or the like. [Function] As mentioned above, according to the film forming method of the present invention, a film having superior low resistance and high infrared reflectance can be obtained, as well as uniform and excellent hardness and chemical and mechanical durability. The film forms a uniform coating, which does not cause distortion or warping of the glass substrate, and the addition of a small amount of fluorocarboxylic acid results in a fast film formation rate, resulting in extremely good productivity, cost, and quality. When coated, it has the characteristic that it does not generate haze, is almost colorless, and has excellent transparency. [Examples] Examples of the present invention will be described below. FIG. 1 schematically shows an apparatus for carrying out the present invention, in which a tin compound is put in an evaporator 1,
For example, heat the carrier gas to a temperature of 100 to 150°C, adjust the pressure with valve 8, pass it through flowmeter 2, heat it to around 200°C with heater 3, and insert it into the evaporator 1 at 100 to 300/min. Then, the tin compound vapor is sent to the CVD nozzle 4. On the other hand, a fluorine compound is put in the evaporator 5, which can be heated but kept at room temperature.The pressure of the carrier gas is adjusted with a valve 9 and passed through a flow meter 6, at a rate of 2 to 5 min. It is inserted into the evaporator 5 to send the fluorine compound vapor to the CVD nozzle 4 together with the tin compound vapor.
A CVD nozzle 4 sprays a mixed vapor of tin and a fluorine compound onto a plate glass 7 heated to 500 to 600° C. in a heating furnace to form a SnO ₂ (F) coating. Example 1 (CH ₃ ) ₂ SnCl ₂ was used as a tin compound, the evaporation temperature was set at 150°C, it was evaporated at a rate of about 40g/min, and heated air heated to 200°C was sent to the evaporator at 200/min. , as a carrier gas along with (CH ₃ ) ₂ SnCl ₂ vapor to the CVD nozzle. On the other hand, using CF ₃ COOH as a fluorine compound, air was inserted into the evaporator at room temperature as a carrier gas for about 3 min.
The CF ₇ COOH vapor in the evaporator is approximately 1g/min.
(The ratio of CF ₃ COOH to (CH ₃ ) ₂ SnCl ₂ is approximately
It is fed into the CVD nozzle while mixing with ( _CH3 ) _2SnCl2 vapor at a _ratio of 0.025) and heated in a heating furnace.
20 sheets of unta coated silicon oxide glass with a size of 300 x 300 mm ² and a thickness of 3 mm heated to 580℃ and 590℃
on the surface being transported at a speed of mm/sec.
Spraying the mixed steam from a CVD nozzle,
A SnO ₇ (F) film was formed. As a result, a SnO ₂ (F) film having a film thickness of 4700 Å, a resistance value of 9 Ω/□, a visible light transmittance of 76%, and an infrared reflectance (10 μ) of 85% was obtained. FIG. 3 shows the transmittance curve and reflectance curve of the SnO ₂ (F) film of this example. Example 2 A SnO ₂ (F) film was formed in the same manner as in Example 1 except that (C ₄ H ₉ )SnCl ₃ was used as the tin compound. As a result, the film thickness was 3500Å, the resistance value was 15Ω/□,
A coating with an infrared reflectance (10μ) of 82% was obtained. Examples 3 to 6 In the same manner as in Example 1, the temperature of the carrier air to the CF ₃ COOH evaporator was varied from room temperature to 50°C, 0.5 to 2.3 g/
min (the ratio of CF ₃ COOH to (CH ₃ ) ₂ SnCl ₂ is about 0.013 to 0.058), that is, 3 to 5/min, and the film was formed at a transport speed of the plate glass of 18 to 25 mm/sec. The results are shown as Examples 3 to 6 in Table 1. Comparative Examples 1 to 4 By using an apparatus as schematically shown in Fig. 2,
(CH ₃ ) ₂ SnCl ₂ at about 40 g/min and CBrF ₃ at 20-40 g/min
g/min ((CH ₃ ) ₂ The ratio of CBrF ₃ to SnCl ₂ is approximately
0.5 to 1.0), that is, 3 to 5/min, respectively, and by changing the transfer speed of the plate glass, etc., the other conditions were the same as in Example 1, Comparative Example 1
~4 samples. The results are shown in Table 2. Comparative Examples 5 _to 9 In _the spray method, ( _C4H9 ) _2Sn ( _CH3CO2 ) ₂ ,
Using the three components OCl ₃ CH ₃ and CF ₃ COOH, a mixed solution with the proportions shown in Table 3 was sprayed at a spray rate of about 3 c.c./sec into a 300 x 300 mm ² heated to a temperature of 590°C. ,
A sample was prepared by spraying it onto the surface of a 3 mm thick plate glass. The results are shown in Table 3. Comparative Examples 10 to 12 In the same manner as Comparative Examples 5 to 9, only the solution was changed, namely, Sn(C ₅ H ₈ O ₂ ) ₄ , CCl ₃ CH ₃ ,
Using the three components of CF ₃ COOH, a mixed solution having the proportions shown in Table 4 was sprayed to prepare a sample. The results are shown in Table 4. [Effects of the Invention] Examples 1 to 6 of the present invention and the transmittance and reflectance curves shown in FIG. As is clear from comparing 2 to 4,
Even if (CH ₃ ) ₂ SnCl ₂ is used, CF ₃ COOH is better.
It has better resistance value and infrared reflectance than CBrF ₃ .

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【table】

【table】

[Table] In the range of 2.5 to 5μ, CF ₃ COOH has better infrared reflectance than CBrF ₃ . Furthermore, it was found that the use of CF ₃ COOH is more economical and preferable in terms of pollution since only a small amount is needed than CBrF ₃ . Furthermore, when comparing the spray method using CF ₃ COOH as a component of the mixed solution shown in Tables 3 and 4 with the examples of the present invention, it is clear that although it is a spray method that does not undercoat silicon oxide, The resistance value and infrared reflectance (10 μ) of the film are also of a grade that is significantly worse and different from the results of the present invention, and the amount of CF ₃ COOH added in this comparative example is also far greater, which is less efficient. It is. As described above, according to the present invention, by applying a small amount of fluorocarboxylic acid to the CVD method and using organic tin halides, film formation can be made more effectively.
A coating with excellent low resistance and high infrared reflectance can be obtained economically, and its excellent quality can be ensured.
It has remarkable effects and can be applied to materials in a wide range of fields.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an apparatus for carrying out the present invention, FIG. 2 is a schematic diagram of an apparatus for a conventional CVD method,
FIG. 3 is a curve showing the transmittance and reflectance of an embodiment of the present invention. 1, 5, 10... Evaporator, 3, 12... Heater, 1
4...Cylinder, 4,13...CVD nozzle, 2,6,
11, 15...Flowmeter, 7,16...Plate glass, 8,
9, 17, 18...Valve.

Claims (1)

[Claims] 1. In a method of forming a tin oxide film by ejecting a mixed vapor of a tin compound, which is an organotin halide, and a fluorine compound onto the surface of a heated glass substrate, fluorocarbon is used as the fluorine compound. 1. A method for forming a transparent conductive thin film, characterized in that an acid is used in a weight ratio of 0.01 to 0.058 to a tin compound. 2 The fluorocarboxylic acid as the fluorine compound is CF ₃ COOH, C ₃ F ₇ COOH, CF ₃ CH=
The method for forming a transparent conductive thin film according to claim 1, wherein CHCOOH is used.