JP3406693B2 - Method for forming tin (IV) oxide film - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a tin (IV) oxide film having high orientation.

[0002]

2. Description of the Related Art Tin (IV) oxide film, which is excellent in chemical stability, abrasion resistance, light transmission, infrared reflectivity, electrical conductivity, etc., is a physical vapor deposition method such as vacuum deposition method, Sputtering method, spray pyrolysis method which is a chemical film forming method, CVD
Method, a sol-gel method or the like can be used to form a film on the substrate. The tin (IV) oxide film is a wear resistant film,
It is widely used as a decorative film, a heat ray reflective film, a transparent conductive film, or the like, or is used in a semiconductor gas sensor.

When a tin (IV) oxide film is formed on a substrate made of an amorphous material such as glass or a silicon oxide film, the crystal growth of tin (IV) oxide is hindered by the influence of the substrate surface, It is said that sufficient conductivity cannot be obtained in a region where the thickness of the tin (IV) oxide film is 0.5 μm or less (for example, see Japanese Patent Laid-Open No. 61-227946). In this publication, in order to address such a problem, a fluorine-undoped tin oxide film for imparting a selective crystallographic orientation is used as a base film of a transparent conductive film made of fluorine-doped tin oxide. The resistance is reduced by emphasizing the crystal orientation of the (211) plane of the transparent conductive film of tin oxide provided on the substrate and doped with fluorine. Then, the tin oxide film not doped with fluorine is formed by a physical film forming method such as a vacuum vapor deposition method, a sputtering method, an ion plating method, or a CVD method or a spray method,
The tin oxide film doped with fluorine is formed by the CVD method. In addition, as a starting material, an alkyltin compound such as tetramethyltin and tetraethyltin, a tin chloride compound such as tin tetrachloride and tin dichloride, an alkyltin chloride compound such as 2 methyltin dichloride and monobutyltin trichloride, and dibutyltin diacetate. Alkyl tin acetate compounds are shown.

Tin oxide (I) having a (200) plane orientation
V) It has been known that the film exhibits a large electric conductivity, or that unevenness is easily formed on the film surface and the light confinement effect is excellent. When the tin (IV) oxide film is used as a transparent conductive film of, for example, a solar cell or a liquid crystal display device, the tin (IV) oxide film is required to have electric conductivity as low as possible. Further, when a tin (IV) oxide film is used as a transparent conductive film of a solar cell, it is required that the antireflection condition is satisfied over a wide spectrum range. Therefore, unevenness of a certain size is formed on the transparent conductive film. Then, means for guiding incident light to the semiconductor layer by multiple reflection is taken.

It is known, for example, from JP-A-2-258691 that the crystal orientation of such a tin (IV) oxide film affects the light confining effect and the specific resistance. According to this publication, SnCl ₄ .5H ₂ O and ammonium fluoride (NH ₄ F) or antimony chloride (Sb) are used.
A raw material solution for a transparent conductive film is prepared by dissolving Cl ₃ ) in a solvent such as water. Then, the raw material solution is atomized to form a transparent conductive film on the glass substrate. At this time, when the substrate temperature rises, the tin (IV) oxide film is oriented to the (110) plane, and the light confinement effect is said to decrease. Therefore, the substrate temperature is first set to 350 to 450 ° C. to form the tin (IV) oxide film, and then the substrate temperature is raised to form the tin (IV) oxide film in two steps. . As a result, tin (IV) oxide oriented in the (200) plane is obtained.
The film can be deposited on a glass substrate.

Alternatively, for example, by interposing an underlayer film containing zirconium oxide (ZrO ₂ ) as a main component between the glass substrate and the tin oxide film, the crystal orientation of the (200) plane of the tin oxide film is enhanced. Japanese Patent Application Laid-Open No. 61-227945 discloses a technique for reducing the resistance of a tin oxide film.

[0007]

As described above, according to the prior art, when an amorphous material such as glass is used, in order to obtain a tin (IV) oxide film having a high orientation, the substrate and the oxide are not oxidized. It is necessary to provide a base film or a kind of buffer layer between the tin (IV) film and the film forming process in two steps. However, the formation of such a base film and buffer layer is complicated, requires an extra step for film formation, and causes a problem of increasing the manufacturing cost of the tin (IV) oxide film. Further, in the two-stage film formation, there is a problem that it takes time to change the substrate temperature and the film formation process becomes complicated. Although it is possible to form a tin (IV) oxide film having high orientation on the substrate by using a single crystal material as the substrate, it causes an increase in the cost of the substrate,
Alternatively, there is a problem that the selection width of the substrate is narrowed.

In the prior art, tin (IV) oxide was used.
The orientation of the tin (IV) oxide film has not been controlled by selecting the film forming material (starting material).

When a tin (IV) oxide film is formed by a vacuum vapor deposition method which is a physical film forming method, vacuum equipment is required,
It is disadvantageous in terms of manufacturing cost. There are also many problems in terms of stoichiometry and step coverage. The CVD method is advantageous in terms of manufacturing cost of the tin (IV) oxide film, but has a problem that the film forming condition width for forming the tin (IV) oxide film having a desired orientation is narrow.

Therefore, an object of the present invention is to eliminate the need to form a buffer layer or the like or to use a single crystal substrate, simplify the manufacturing process, and facilitate a tin (IV) oxide film having a desired orientation. Another object of the present invention is to provide a method for forming a tin (IV) oxide film, which makes it possible to form a film under a wide range of film formation conditions.

[0011]

A method for forming a tin (IV) oxide film according to the present invention for achieving the above object is described below.

[Chemical 2] An organotin compound consisting of R ₁ and R ₃ in the first step and R ₂ and R ₄ in the second step, thereby forming a film of tin (IV) oxide on the substrate. Characterize.

The following can be exemplified as combinations of R ₁ , R ₂ , R ₃ and R ₄ .

[Table 1] R ₁ R ₂ R _{3 R 4 C 4 H 9 CH 3} C 4 H 9 CH 3 C 4 H 7 CH 3 C 4 H 7 CH 3 C 4 H 9 CH 3 C 2 H 5 CH 3 C 4 H 9 CH 3 C 4 H 9 C 2 _{H 5 C 4 H 9 CH 3} C 2 H 5 C 2 H 5 C 3 H 7 CH 3 C 3 H 7 CH 3

In the method for forming a tin (IV) oxide film according to the present invention, the tin (IV) oxide film formed on the substrate is formed on the (200) plane by using the above organic tin compound as a starting material. Has an orientation.

In the method for forming a tin (IV) oxide film according to the present invention, the sprayed organotin compound is in the first and second stages before the organotin compound is sprayed and reaches the substrate. Embodiments that undergo degradation can be included. In this case, it is desirable that a temperature distribution be formed along the flow of the organotin compound in the space region through which the organotin compound passes before the organotin compound is sprayed and reaches the heated substrate. Furthermore, the temperature in the space region where the first-stage decomposition of the organotin compound occurs is 26
0 to 320 ° C, preferably 270 to 310 ° C,
More preferably, the temperature is 280 to 300 ° C, and the temperature of the space region where the second stage decomposition occurs is 320 to 580 ° C.
Preferably 355 to 530 ° C, more preferably 43
0 to 480 ° C, and the heating temperature of the substrate is 355 to 5
80 ° C, more preferably 430 ° C to 530 ° C,
More preferably, the temperature is 480 to 530 ° C.

When the temperature of the space region where the first-stage decomposition of the organotin compound occurs is less than 260 ° C., the first-stage decomposition of the organotin compound is difficult to occur. Also, if the temperature of the spatial region where the first stage decomposition occurs exceeds 320 ° C,
The second-stage decomposition starts at the same time, the orientation of the formed tin (IV) oxide film decreases, and the tin oxide (I) powder
V) is easily generated. When the temperature of the space region in which the second-stage decomposition of the organotin compound occurs is less than 320 ° C., the second-stage decomposition of the organotin compound hardly occurs. Also,
When the temperature of the space region where the second-stage decomposition occurs exceeds 580 ° C., tin (IV) oxide is not formed into a film and powdery tin (IV) is easily generated. If the substrate heating temperature is less than 355 ° C, the tin (IV) oxide film (200)
The orientation of the surface drops sharply. Further, when the heating temperature of the substrate exceeds 580 ° C., tin (IV) oxide is not formed into a film and powdery tin (IV) oxide is easily generated. As a result of various experiments, within the above range, the higher the heating temperature of the substrate, the higher the (200) plane orientation of tin oxide (I).
V) It has been found that a film can be obtained.

The space region in which the first-stage decomposition of the organotin compound occurs is preferably 1 cm or more away from the substrate surface. If it is less than 1 cm, the incorporation of carbon as an impurity into the tin (IV) oxide film becomes significant. The spatial region in which the second-stage decomposition of the organotin compound occurs is preferably within 1 cm from the surface of the substrate.

In the method for forming a tin (IV) oxide film of the present invention, it is desirable that the organotin compound is dissolved in alcohol. In this case, the concentration of the organotin compound in the alcohol solution is 0.1% by weight in terms of SnO _2.
The amount is preferably 10% by weight or less, more preferably 0.1% by weight to 3% by weight, still more preferably 0.1% by weight to 1% by weight. If the concentration of the organotin compound in the alcohol solution exceeds 10% by weight, the tin (IV) oxide film may not be crystalline but may be amorphous depending on the heating temperature of the substrate. If it is less than 0.1% by weight,
There is a tendency that microcrystalline material with low orientation is likely to be formed. Various experiments have revealed that within the above range, the lower the concentration of the organotin compound contained in the alcohol solution, the more the tin (IV) oxide film having a high (200) plane orientation can be obtained.

When the organotin compound is dissolved in alcohol, the alcohol solution containing the organotin compound is applied to the substrate at 1 × 10 ^{−3 to} 5 × 10 ⁻² cm ³ / sec · c.
m ² , preferably 5 × 10 ^{−3 to} 1 × 10 ⁻² cm ³ / sec.
It is desirable to spray it in cm ² . When the amount of the alcohol solution containing the organotin compound sprayed on the unit area (1 cm ² ) of the substrate exceeds 5 × 10 ^-2 cm ³ / sec · cm ² ,
There is a possibility that the temperature change of the substrate becomes large and a tin (IV) oxide film having high orientation cannot be formed on the substrate. On the other hand, the spray amount on the substrate is 1 × 10 ^-3 cm ³ / sec.
If it is less than cm ² , a film of microcrystals having a low orientation tends to be formed.

It is desirable that the growth rate of the tin (IV) oxide film formed on the substrate is 0.5 to 40 nm / sec, more preferably 1 to 10 nm / sec. When the growth rate of the tin (IV) oxide film exceeds 40 nm / sec, (2
The (00) plane orientation sharply decreases. In addition, tin oxide (I
V) When the growth rate of the film is less than 0.5 nm / sec, it tends to be easy to form a film of fine crystals with low orientation.
According to various experiments, tin oxide (I
It was found that the slower the growth rate of the V) film, the more the tin (IV) oxide film having the higher (200) plane orientation can be obtained.

In the present specification, the tin (IV) oxide film includes not only the SnO ₂ film but also SnO _x (where 1 <X <2) deviated from the stoichiometric composition.

[0021]

In the present invention, in order to form a tin (IV) oxide film having a specific orientation, the decomposition of the first step and the second step is mainly performed, so that mainly O-Sn-O bonds are formed. It is considered that the decomposition of the organotin compound is completed in the state of holding, and the organic tin compound is attached to the surface of the substrate in this state to form a film as tin (IV) oxide. By controlling the decomposition of the organotin compound in two stages in this way, a tin (IV) oxide film having a high (200) plane orientation can be formed on the substrate. Incidentally, in order to complete the decomposition of the organotin compound mainly in the state where the O—Sn—O bond is retained, as described above, the organotin composed of R ₁ R ₃ Sn (OCOR ₂ ) (OCOR ₄ ) is used. The compound must be selected as the starting material.
When the organotin compound is decomposed by the one-step decomposition process without passing through the two-step decomposition process (that is, when the first-step decomposition and the second-step decomposition are simultaneously generated), one of the organotin compounds is The parts reach the substrate before the second-stage decomposition occurs, and the orientation of the formed tin (IV) oxide film is deteriorated. In the present invention, it is not necessary to previously form a buffer layer or the like on the substrate or to use a single crystal substrate, and the manufacturing process can be simplified.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

First, an outline of a spray pyrolysis apparatus suitable for carrying out the present invention will be described with reference to FIG. The spray pyrolysis apparatus includes an organotin compound raw material supply unit 10, a carrier gas supply unit 20, an atomization unit 30, and a substrate holding unit 40.
And an auxiliary heater 50. The organotin compound raw material supply unit 10 includes an organotin compound raw material storage unit 11
And a pump 12, a flow meter 13, and a pipe 14.
The carrier gas supply unit 20 includes, for example, a compressed gas generation / supply device 21, a flow meter 22, and a pipe 23.
The atomizing unit 30 is a two-fluid spray gun. The base body 60 is held in the base body holding portion 40. And the base holding portion 4
The base body 60 is heated to a predetermined temperature by the heater 41 provided in the No. 0. The temperature of the base body 60 is measured by a sheath type thermocouple (not shown) in contact with the side surface of the base body 60,
The heater 41 is controlled by the PID controller. As a result, the temperature of the substrate 60 in a state where the organotin compound raw material was not sprayed on the substrate 60 was maintained at a predetermined constant temperature. The heating temperature of the substrate means the temperature of the substrate 60 in a state where the organotin compound raw material is not sprayed on the substrate 60.

Between the atomizing section 30 and the substrate holding section 40,
For example, a ring-shaped auxiliary heater 50 is provided. As a result, a temperature distribution is formed along the flow of the organotin compound in the spatial region through which the organotin compound passes by the time the organotin compound is sprayed and reaches the heated substrate 60. Specifically, the ring-shaped auxiliary heater 50
The atomized organotin compound passes through the space region 70 formed in the central portion of the. A sheath type thermocouple (not shown) is arranged in the space region 70, the temperature of the space region 70 is measured by this, and the auxiliary heater 50 is controlled by the PID controller. With this, the temperature of the space region 70 in a state where the organotin compound raw material was not sprayed on the substrate 60 was maintained at a predetermined constant temperature.

In the space region 70 heated by the auxiliary heater 50, mainly the first-stage decomposition of the organotin compound occurs. It should be noted that the temperature of the space region 70 means the substrate 60.
It means the temperature measured on the axis of the atomizing unit 30 toward the. When the temperature is distributed in the space area 70, the maximum temperature is defined as the temperature of the space area 70.

On the other hand, when the base body 60 is heated by the heater 41, the radiant heat from the base body 60 heats the space region 71 above the base body 60. In this space region 71, the second-stage decomposition of the organotin compound mainly occurs.

In the embodiment, the atomizing section 30 and the base 60 are provided.
The distance between the auxiliary heater 50 and L (= 20 cm)
Was placed 0.25 L (= 5 cm) from the surface of the substrate 60. The inner diameter of the ring-shaped auxiliary heater 50 was 10 cm, and the height H was 2 cm. The distance between the upper end of the auxiliary heater 50 and the atomizing unit 30 is 14 cm. In this case, the temperature of the space region 70 is 5 cm from the surface of the substrate 60.
It was the temperature in a distant space area.

The growth of the tin (IV) oxide film on the substrate 60 was performed by the intermittent method. One-time organotin compound substrate 60
The substrate 60 is lowered by 15 to 25 ° C. Further, the temperatures of the space regions 70 and 71 also decrease. Therefore, after the organotin compound was sprayed onto the substrate 60, the temperature of the substrate 60 was restored to a predetermined temperature, and then the organotin compound was sprayed onto the substrate 60 again. It should be noted that the spraying time of the organotin compound onto the substrate 60 once was 1 second. The pressure of the compressed air supplied to the atomizing unit 30 was set to a gauge pressure of 1 kg / cm ² .

As the substrate 60, Corning # 7059 glass (25 mm × 25 mm × 1 m, Corning Incorporated, USA) is used.
m) was used. The distance (L) from the atomizing unit 30 to the base 60 was set to 10 cm. Also, as alcohol,
Isopropyl alcohol-modified (13.6%) ethyl alcohol was used.

The orientation of the tin (IV) oxide film was evaluated by the high speed electron diffraction method and the X-ray diffraction method. As an X-ray diffractometer, Shimadzu Corporation XD-610 type X-ray diffractometer was used, and CuKα rays were used. Grown tin (IV) oxide
The percentage of the X-ray integrated intensity I _hkl from the (hkl) plane with respect to the total X-ray integrated intensity ΣI _hkl from all the crystal planes of the film was defined as the orientation degree α. α = (I _hkl / ΣI _hkl ) × 100

(C ₄ H ₉ ) ₂ Sn (OCOCH ₃ ) as a raw material for an organic tin compound for forming a tin (IV) oxide film
An ethyl alcohol solution containing ₂ was used. That is, R ₁
And R ₃ are C ₄ H ₉ and R ₂ and R ₄ are CH ₃ . The (C ₄ H ₉ ) ₂ Sn (OCOCH ₃ ) ₂ content concentration in the alcohol solution was set to 1% by weight in terms of SnO ₂ .

Example 1 A tin (IV) oxide film was formed on a substrate 60 by using the spray pyrolysis apparatus shown in FIG. The space area 70 is moved to 290 ° C by the auxiliary heater 50.
Held in. At this time, the temperature distribution pattern formed along the flow of the organotin compound in the space region through which the organotin compound passes by the time the organotin compound is sprayed and reaches the heated substrate is shown in FIG. Shown by curve A.

The substrate 60 was held by the substrate holding section 40, and the substrate 60 was heated to a predetermined temperature (500 ° C.) by the heater 41. As a result, the space region 71 above the substrate 60 where the second-stage decomposition of the organotin compound mainly occurs is about 3
Heated to 20 ° C. A tin (IV) oxide film was formed on the substrate 60 with the amount of ethyl alcohol solution sprayed once being 4 × 10 ⁻³ cm ³ / sec · cm ² . The growth rate of the tin (IV) oxide film formed on the substrate was set to 3 nm / sec.

When a film having a thickness of 9 nm was formed on the substrate, the film was measured by a reflection type high-energy electron diffraction method, and it was found that the film was made of tin (IV) oxide and that
The (00) plane was preferentially oriented. Thus, (200)
An extremely thin tin (IV) oxide film having plane orientation is not obtained from the conventional technique, but is obtained for the first time by the method for forming a tin (IV) oxide film of the present invention. Further film formation is continued, and tin oxide (I
After obtaining the V) film, the orientation of the tin (IV) oxide film was evaluated by the X-ray diffraction method. As a result, it was found that the obtained tin (IV) oxide film was highly oriented on the (200) plane. Sum of the X-ray integrated intensities from each (hkl) plane ΣI
later for values of orientation degree α is the percentage of X-ray integral intensity I _hkl from (hkl) face against _hkl.

(Comparative Example 1) For comparison, an auxiliary heater 5 was used.
0 is turned off, and tin oxide (I
V) A film was formed. The temperature distribution pattern formed along the flow of the organotin compound in the spatial region at this time is shown by the curve B in FIG.

Comparative Example 2 For comparison, the auxiliary heater 5
The tin (IV) oxide film was formed under the same conditions as in Example 1 while maintaining the space region 70 at 220 ° C. by 0.
The temperature distribution pattern formed along the flow of the organotin compound in the spatial region at this time is shown by a curve C in FIG.

(Comparative Example 3) For comparison, an auxiliary heater 5 was used.
The tin (IV) oxide film was formed under the same conditions as in Example 1 while maintaining the space region 70 at 430 ° C.
The temperature distribution pattern formed along the flow of the organotin compound in the spatial region at this time is shown by the curve D in FIG.

The value of orientation degree α (unit:%) obtained from the X-ray integrated intensity measurement in Example 1 and Comparative Examples 1 to 3 is
It was as follows. In Comparative Example 3, only tin (IV) oxide powder was obtained.

[0039]

[Table 2]                 Example 1 Comparative Example 1 Comparative Example 2 (200) plane 94.7 93 93.4 (211) plane 0 0.5 0.4 (310) plane 2.6 5.8 5.6 (301) plane 0 0.7 0.6 Other surface Trace Trace Trace

In the first embodiment, the heating temperature by the auxiliary heater 50 and the heater 41 is appropriate, and in the organic tin compound, in the space region 70, R ₁ and R ₃ are first decomposed in the first stage, and then, Second in the space area 71
At the stage, R ₂ and R ₄ are decomposed, and the decomposition of the organotin compound is completed in the state where the O—Sn—O bond is retained, and in this state, the tin (IV) film is attached to the surface of the substrate to form a tin (IV) film. Base 6
Formed on 0. Thus, by controlling the decomposition process of the organotin compound in two stages, (200)
A tin (IV) oxide film having high orientation on the surface can be formed.

In Comparative Example 1, the organotin compound is
The substrate 60 is exposed to a rapid temperature rise in the vicinity thereof. In this case, the two-step decomposition of the organotin compound is almost simultaneously performed on the substrate 6
It occurs in the space region 71 near 0, and a part of the organotin compound reaches the substrate 60 before the second-stage decomposition occurs. As a result, the orientation of the formed tin (IV) oxide film becomes low. In Comparative Example 2, although the organotin compound undergoes the first-stage and second-stage decomposition, the first-stage decomposition is not sufficient, and thus the formed tin (IV) oxide film has sufficiently high orientation. Is hard to say.

On the other hand, in Comparative Example 3, the spatial region 70
In, not only the first-stage decomposition of the organotin compound but also the second-stage decomposition occurs. Highly reactive decomposition products (mainly SiO _x ,
However, 1 <X ≦ 2) does not reach the substrate 60 immediately and is exposed to a temperature higher than the temperature required for the second-stage decomposition for a while. As a result, the tin oxide (I
V) The orientation of the film is reduced, and tin (IV) oxide powder is used.
Are easily generated.

As described above, the tin (IV) oxide of the present invention
In the film forming method, by controlling the auxiliary heater 60, an appropriate temperature distribution is formed along the flow of the organotin compound in the space region where the organotin compound passes, and as a result, the decomposition of the organotin compound is prevented. Fine control was possible in the first step and the second step, and a tin (IV) oxide film having a high (200) orientation could be formed on the substrate. It is to be noted that, unlike the prior art, it is not necessary to provide a buffer layer on the surface of the substrate, and the tin (IV) oxide film having high orientation from the initial stage of film formation without changing film forming conditions during film formation. Can be formed.

(Example 2) The heating temperature of the substrate 60 was set to 430.
(2) on the substrate in the same manner as in Example 1 except that
A tin (IV) oxide film having a (00) plane orientation was formed.
An ethyl alcohol solution containing (C ₃ H ₇ ) ₂ Sn (OCOCH ₃ ) ₂ was used as an organic tin compound raw material for forming the tin (IV) oxide film. That is, R ₁ and R ₃ were C ₃ H _7, and R ₂ and R ₄ were CH ₃ . The alcoholic solution of _{(C 3 H 7) 2 Sn} (OCOCH 3) 2 containing concentration was 1 wt% in terms of SnO _2. Tin oxide (IV)
When the degree of orientation α of the (200) plane of the film was measured, it had a high degree of orientation α as shown below. (200) plane α = 81.9% (211) plane α = 6.4% (310) plane α = 5.3% (301) plane α = 6.4% Other plane α = trace

Although the present invention has been described based on the preferred embodiments, the present invention is not limited to these embodiments. The conditions and numerical values described in the examples are examples,
It can be changed appropriately. The substrate is not limited to various glasses such as soda lime silicate glass, aluminosilicate glass, borosilicate glass, lithium aluminosilicate glass, and quartz glass, and tin oxide (I
V) Various inorganic material films, organic material films, and the like on which the film is to be formed can be used. As the alcohol, other than ethyl alcohol, isopropyl alcohol, butanol and the like can be used. In spraying the organotin compound, not only compressed air but also mixed gas of pressurized nitrogen gas, pressurized argon gas and pressurized oxygen gas may be used. The tin (IV) oxide film formed on the substrate may be annealed.

The tin (IV) oxide film having a high (200) plane orientation obtained by the method for forming a tin (IV) oxide film according to the present invention is, for example, a liquid crystal display device, an electroluminescence display device, a plasma display device, It can be applied to a transparent conductive film in various display devices such as an electrochromic display device. It can also be applied to a transparent conductive film that also serves as an antireflection film of a solar cell. In these cases, if necessary, a dopant composed of a compound of fluorine (F) or antimony (Sb) is appropriately added to the organotin compound raw material, or the dopant is atomized simultaneously with atomization of the organotin compound raw material. By doping the formed tin (IV) oxide film, it is possible to further reduce the resistance of the tin (IV) oxide film. Further, an alkali barrier layer made of, for example, SiO ₂ may be formed on the surface of the substrate in order to prevent precipitation of alkali components such as sodium and potassium from the substrate made of glass. Furthermore,
If necessary, a protective layer, an antireflection layer or the like may be provided on the surface of the tin (IV) oxide film.

Further, by using the method for forming a tin (IV) oxide film of the present invention, a thin film resistor, an infrared reflecting film (for example, P
Application to a transparent heat insulating film having a tin (IV) oxide film formed on the surface of an ET film), a current-carrying heater for anti-fog windows for freezing showcases, a conductive film for preventing electrostatic charging of electric parts, and Cu doping It is possible to produce the above oxide photochromic material.

Alternatively, the tin (IV) oxide film forming method of the present invention can be applied to the spatial light modulating element as disclosed in JP-A-63-23128. In this case, based on the method for forming a tin (IV) oxide film of the present invention, tin oxide having high orientation is formed on a substrate made of a sapphire, a single crystal such as LiF, or a glass material such as quartz or glass. After the conductive crystal axis orientation film made of the film (IV) is formed, a ferroelectric layer made of, for example, Sr ₂ KNb ₅ O ₁₅ , potassium tantalum niobate or the like is laminated thereon. Further thereon, a photoconductor layer made of II-VI group, chalcogen group, IV group group and GeC, SiC or organic photoconductor material is laminated, and the surface of the photoconductor layer and the back surface of the substrate are laminated. A transparent electrode is formed on. In this way, the spatial light modulator can be manufactured.

The method for forming a tin (IV) oxide film of the present invention can be further applied to the formation of a wear resistant film such as a surface coating of a lens or a decorative film in a show window.

[0050]

According to the method for forming a tin (IV) oxide film of the present invention, the tin (IV) oxide having a high orientation is obtained by decomposing the organotin compound in the first step and the second step. ) The film can be deposited on a substrate. Moreover, it is not necessary to previously form a buffer layer or the like on the substrate or to use a single crystal substrate, and the manufacturing process can be simplified. Further, a tin (IV) oxide film having a desired orientation can be easily and surely formed under a wide range of film forming conditions.

Moreover, if the method for forming a tin (IV) oxide film of the present invention is carried out by the spray pyrolysis method, no large-scale production equipment is required, and the production cost of the tin (IV) oxide film is reduced. can do.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a spray pyrolysis apparatus suitable for carrying out a tin (IV) oxide film forming method of the present invention.

FIG. 2 is a diagram schematically showing a temperature distribution pattern in a spatial region in which an organotin compound decomposes.

[Explanation of symbols]

10 Organic tin compound raw material supply department 11 Organic tin compound raw material storage 12 pumps 13 Flowmeter 14 Piping 20 Carrier gas supply section 21 Compressed gas generator / supply unit 22 Flow meter 23 Piping 30 Atomization unit 40 Base holding part 41 heater 50 auxiliary heater 60 base

Claims (7)

(57) [Claims] 1. Of tin (IV) oxide using an organic tin compound consisting of
A method of forming a tin (IV) oxide film on a substrate, comprising: forming a space in the space through which the organotin compound passes by the time the organotin compound is sprayed and reaches the heated substrate. , A temperature distribution is formed along the flow of the organotin compound, and the space region is
It is composed of a first space region and a second space region, and the temperature of the first space region is 260 to 320 ° C.,
The temperature of the second space region is set to 320 to 580 ° C,
A method for forming a tin (IV) oxide film, wherein the heating temperature of the substrate is 355 ° C to 580 ° C. 2. The method for forming a tin (IV) oxide film according to claim 1, wherein the tin (IV) oxide film formed on the substrate mainly has a (200) plane orientation. 3. The method for forming a tin (IV) oxide film according to claim 1, wherein the first space region is separated from the substrate surface by 1 cm or more. 4. The organotin compound is dissolved in alcohol, and the concentration of the organotin compound in the alcohol solution is 0.1 wt% or more and 10 wt% or less in terms of SnO _2. The method for forming a tin (IV) oxide film according to any one of claims 1 to 3. 5. The organotin compound is dissolved in alcohol, and the content of the organotin compound in the alcohol solution is 0.1 wt% or more and 1 wt% or less in terms of SnO _2. The method for forming a tin (IV) oxide film according to any one of claims 1 to 3. 6. The alcohol solution containing an organotin compound is applied to the substrate at 1 × 10 ^{−3 to} 5 × 10 ⁻² cm ^3.
/ Sec · cm ^{2 is} sprayed, The method for forming a tin (IV) oxide film according to claim 4 or claim 5, 7. Tin (IV) oxide deposited on the substrate
The method for forming a tin (IV) oxide film according to any one of claims 1 to 6, wherein a growth rate of the film is set to 0.5 to 40 nm / sec.