JP3386756B2 - Thin film forming method and thin film forming apparatus - 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 and apparatus for forming thin films of metal oxides and metal sulfides used in photoelectric conversion elements, display elements and the like.

[0002]

2. Description of the Related Art Conventionally, compound semiconductors, particularly metal oxide thin films and metal sulfide thin films, have been widely used as materials for photoelectric conversion elements and display elements. And many of these compounds have been conventionally manufactured by the sputtering method, the vapor deposition method, and the like. According to these methods, it is easy to obtain a thin film having a desired film quality, but it is difficult to form a large-area uniform thin film and continuous high-speed film formation, and a vacuum device is required, which makes the device very expensive. There was a problem.

Therefore, as a method for inexpensively forming a thin film of a metal sulfide or a metal oxide without the need for a vacuum device, a thermal decomposition method of a metal compound has been studied. For example, a method of thermally decomposing an organometallic compound having at least one metal-sulfur bond on a source substrate to form a metal sulfide thin film on an opposing film-forming substrate (for example, Japanese Patent Laid-Open No. 8-316).
No. 247) has been proposed. However, this method requires that a source substrate on which a source material layer is formed be produced, and that the source substrate and the film-forming substrate must be uniformly brought close to each other at a constant interval, which complicates the process. There was a problem in forming a large-area thin film.

Further, the solution of the organometallic compound is atomized by an ultrasonic oscillator to be fine particles, and the fine particles are sprayed onto a pre-heated film-forming substrate together with a carrier gas such as air or nitrogen. Thermal decomposition of the compound,
A method of forming a metal sulfide thin film on the film-forming substrate (for example, Japanese Patent Laid-Open No. 11-87747) has been proposed.
However, in the thermal decomposition method by atomizing the metal compound solution as described above, the amount of fine particles of the atomized solution generated due to the change of the viscosity with the temperature change of the solution and the change with time of the ultrasonic vibrator. Change, and it was difficult to control this within a certain range. Therefore, there is a problem in that a metal sulfide or metal oxide thin film having a uniform film thickness cannot be formed.

The above problems are common problems in forming various thin films. Examples of the metal sulfide thin film having the above problems include cadmium sulfide (CdS), zinc sulfide (ZnS), and CdS used in solar cells, phosphors, and the like.
Mixed with ZnS and lead sulfide (P
There is a thin film such as bS). Examples of the metal oxide thin film include tin dioxide (SnO ₂ ), indium oxide (In ₂ O ₃ ), and indium tin oxide (SnO ₂ and I) which are used as transparent conductive films for solar cells and display displays.
There are thin films of mixed crystals with n ₂ O ₃ ) and zinc oxide (ZnO).

[0006]

DISCLOSURE OF THE INVENTION In the present invention, fine particles of a solution of a metal compound solution (hereinafter referred to as a source material solution) are sprayed onto a film-forming substrate to produce a metal compound (hereinafter referred to as a source material). ) Is thermally decomposed to solve the above problems of the thin film forming method of forming a thin film of a metal sulfide or a metal oxide on the film forming substrate, requiring expensive equipment such as a vacuum device and complicated steps. First, it is an object of the present invention to provide an inexpensive method for forming a thin film having a uniform film thickness and an apparatus for carrying out the method.

[0007]

According to the present invention, a source material solution in which a source material is dissolved in a solvent is atomized by an ultrasonic vibrator, and fine particles of the atomized solution are contained in a carrier gas for spraying. Is sprayed on the surface of a pre-heated film-forming substrate, and the source material in the fine particles is thermally decomposed to form a thin film of a metal oxide or a metal sulfide on the film-forming substrate. The content of the fine particles in the blowing gas, the content of the decomposition gas of the source material in the exhaust gas, or the vapor concentration of the solvent in the exhaust gas is measured, so that the measured value is an appropriate value. The present invention relates to a method for forming the thin film while controlling the output of an ultrasonic oscillator.

In the present invention, means for atomizing a source material solution in which a source material is dissolved in a solvent by an ultrasonic oscillator, and fine particles of the atomized solution are contained in a carrier gas to obtain a spraying gas. And a means for heating the film-forming substrate, the gas for blowing is sprayed on the surface of the film-forming substrate that has been heated in advance, and the source material in the fine particles is thermally decomposed to form the film-forming substrate. A thin film forming apparatus for forming a thin film of a metal oxide or a metal sulfide thereon, wherein the content of the fine particles in the blowing gas is measured, and the ultrasonic transducer is set so that the measured value becomes an appropriate value. Means for controlling the output, measuring the content of decomposed gas of the source material in the exhaust gas, means for controlling the output of the ultrasonic oscillator so that the measured value becomes an appropriate value, or in the exhaust gas Vapor of the solvent Degrees were measured, a thin film forming apparatus characterized by comprising means for controlling the output of the ultrasonic vibrator so that the measured value becomes an appropriate value.

This makes it possible to form a thin film while always maintaining the generation rate of the fine particles of the atomized source material solution and the content of the fine particles in the blowing gas within an appropriate range. As a result, since the source material is supplied onto the film-forming substrate at a constant rate, a thin film can be formed at a constant rate, and a metal oxide or metal sulfide thin film having a uniform thickness can be obtained. The content of the fine particles in the blowing gas is preferably measured by the light transmittance of the blowing gas. The metal oxide is preferably tin dioxide. Further, the metal sulfide,
It is preferably cadmium sulfide, zinc sulfide, or a mixed crystal of cadmium sulfide and zinc sulfide.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The first thin film forming method of the present invention comprises:
The content of the solution particles in the blowing gas is measured, and the output of the ultrasonic oscillator is controlled by the measured value. An apparatus suitable for carrying out the first method is
For example, while performing film formation, the content of the solution particles in the blowing gas is measured at the same time, and the content is fed back to the output controller of the ultrasonic vibrator to maintain the content of the solution particles within an appropriate range. As described above, it has means for increasing or decreasing the input voltage to the ultrasonic transducer.

Further, in a preferred method for carrying out the present invention, the light transmittance of the blowing gas is measured, and from the measured value, the solution fine particles in the blowing gas having a certain correspondence with the measured value are obtained. This is a method of determining the content. When a blowing gas containing a large number of solution particles is irradiated with light, light is diffusely reflected or absorbed by these solution particles, and the intensity of transmitted light changes depending on the density of the solution particles existing in the space. Therefore, the content of the solution particles can be measured by measuring the light transmittance of the blowing gas.

Suitable means for carrying out the above method comprises a laser light source and a light receiving element provided at a fixed distance from the laser light source, and receives the intensity of the laser light after being irradiated from the laser light source and passing through the blowing gas. Detected by the element,
Means for determining the content of the solution fine particles from the light transmittance can be mentioned.

The second thin film forming method of the present invention is to measure the content of the decomposition gas of the source material contained in the exhaust gas,
The output of the ultrasonic transducer is controlled according to the measured value. The amount of decomposed gas after thermal decomposition is proportional to the amount of the source material used for forming the thin film, and the rate at which the source material in the blowing gas is used for forming the thin film is almost constant.
In other words, the measured value of the content of the decomposition gas in the exhaust gas is proportional to the content of the solution particles in the blowing gas. Therefore, this method has substantially the same effect as the method of controlling the output of the ultrasonic vibrator so that the content of the solution particles in the blowing gas becomes an appropriate value.

An apparatus suitable for carrying out the second method, for example, measures the content of the decomposition gas of the source material in the exhaust gas at the same time while performing film formation, and outputs the content to the output of the ultrasonic transducer. It has means for feeding back to the controller and increasing or decreasing the input voltage to the ultrasonic transducer so that the content of the decomposed gas is maintained within an appropriate range. The means for measuring the content of the decomposed gas is composed of an infrared light source and an infrared light receiving element provided at a constant distance from the infrared light source, is incident from the infrared light source, and is absorbed by the decomposed gas after passing through exhaust gas. There is a means for detecting the intensity of infrared rays having a wavelength with an infrared light receiving element and obtaining the content of the decomposed gas from the light transmittance thereof.

The third thin film forming method of the present invention is to measure the vapor concentration of the solvent of the source material solution contained in the exhaust gas and control the output of the ultrasonic transducer according to the measured value. . The amount of the solvent contained in the exhaust gas is proportional to the content of the solution particles in the blowing gas, also in this method, so that the content of the solution particles in the blowing gas is an appropriate value. This has substantially the same effect as the method of controlling the output of the ultrasonic transducer.

An apparatus suitable for carrying out the third method is, for example, simultaneously measuring the vapor concentration of the solvent in the exhaust gas while performing film formation and feeding back the concentration to the output controller of the ultrasonic transducer. , A means for increasing or decreasing the input voltage to the ultrasonic transducer so that the vapor concentration of the solvent is maintained within an appropriate range. As a means for measuring the vapor concentration of the solvent, a solvent vapor concentration sensor (when the solvent is water, a ceramic humidity sensor is installed at a position where the temperature of the exhaust gas gradually cooled in the exhaust pipe becomes a predetermined temperature. Preferred).

Of the first to third methods, the first method is preferable from the viewpoint of speed of control feedback. The first method is a method in which the content of fine particles in the gas for spraying before being subjected to film formation is measured and feedback is applied. On the other hand, the second and third methods are methods of measuring the decomposition gas concentration or the solvent vapor concentration in the exhaust gas after being subjected to the film formation and applying the feedback. It can be said that the first and second methods are preferable because the second and third methods provide slower feedback than the first method.

There are various thin films of metal sulfides or metal oxides formed by the above method, as exemplified above, and the metal compounds used as the source material thereof are exemplified below. Among metal sulfides, for example, cadmium dibutyldithiocarbamate is mainly used for forming a thin film of CdS, but cadmium diethyldithiocarbamate or the like can also be used. Further, zinc dibutyldithiocarbamate for forming a thin film of ZnS, a mixture of cadmium dibutyldithiocarbamate and zinc dibutyldithiocarbamate for forming a mixed crystal of CdS and ZnS, Pb.
For forming a thin film of S, lead diethyldithiocarbamate or the like can be used.

Of the metal oxides, dimethyltin dichloride is mainly used for forming the SnO ₂ thin film, but trimethyltin chloride or the like can also be used. Further, indium sulfate can be used for forming a thin film of In ₂ O ₃ , a mixture of indium sulfate and tin sulfate can be used for forming a thin film of ITO, and a metal compound such as zinc acetate can be used for forming a thin film of ZnO. Then, a solution obtained by dissolving these source materials in an organic solvent such as toluene or a solvent such as water is used as a source material solution.

As the film-forming substrate, a translucent substrate such as glass, a heat-resistant substrate such as metal or ceramic, or a substrate on which a base film is preliminarily formed, depending on the intended use of the thin film to be formed. Can be used. As the carrier gas, an inert gas such as nitrogen is used when forming a metal sulfide thin film, and an oxygen-containing gas such as air is used when forming an oxide thin film.

The thin film obtained by these methods is widely used for photoelectric conversion elements such as solar cells and display displays as described above. In particular, the SnO ₂ thin film formed by the present invention is used, for example, for solar cells. Since the resistance value of the transparent conductive film is made uniform by using it as a transparent conductive film, the fill factor of the solar cell becomes constant, and it is possible to manufacture a high quality solar cell with less variation in conversion efficiency. Further, by using this SnO ₂ thin film as a transparent electrode, a high quality liquid crystal or touch panel can be constructed.

Furthermore, it is particularly effective to use the CdS thin film, ZnS thin film or a mixed crystal film thereof obtained by the present invention as an n-type semiconductor film of a CdTe solar cell. When the film thickness of an n-type semiconductor film such as a CdS film of a CdTe-based solar cell is too thin, the open circuit voltage and conversion efficiency of the solar cell decrease, and when the film thickness is too large, the short-circuit current decreases and the conversion efficiency decreases. descend. Therefore, it is possible to stabilize the conversion efficiency at a high level by using the thin film of the n-type semiconductor formed according to the present invention and having a uniform film thickness in these solar cells.

[0023]

EXAMPLES The present invention will be described in more detail with reference to specific examples. 1, 2 and 3 are conceptual illustrations of examples of the three types of apparatus used to carry out the method of the present invention. First, steps common to FIGS. 1, 2, and 3 will be described. The source material solution 3 is atomized by the ultrasonic vibrator 2 in the atomization container 1, and the atomized solution particles 4 are mixed and sprayed into the carrier gas 6 introduced into the atomization container 1 from the introduction pipe 5. Use gas 7

The film forming substrate 11 is placed on the heating plate 10 which is fixed on the support 17 and which is preheated by the heater 9. The gas for spraying 7 transported by the transport pipe 8 is blown onto the film-forming substrate 11 to form the film-forming substrate 11 described above.
The source material in the solution fine particles is thermally decomposed on the surface of to form the metal oxide or metal sulfide thin film 12. Since the above-mentioned steps were commonly performed in each of the following Examples and Comparative Examples, they will be omitted in the following individual explanations.

Example 1 The thin film forming apparatus of FIG. 1 which detects the content of the solution fine particles 4 in the blowing gas 7 and controls the output of the ultrasonic transducer 2 in accordance with the measured value, A SnO ₂ thin film was formed. As the source material solution 3, a solution prepared by dissolving 100 g of dimethyltin dichloride in 360 g of water, a frequency of the ultrasonic oscillator 2 of 1 MHz, a 100 mm square glass substrate is used as the film forming substrate 11, and the film forming substrate 11 is heated. The temperature was 550 ° C., and the film formation time per sheet was 100 seconds. The carrier gas 6 has a dew point of -5.
The flow rate was set to 20 liters / minute using dry air at 0 ° C. Immediately after the film formation on one film-forming substrate 11 was completed, a subsequent film-forming substrate was supplied to continuously form 37 thin films. The standard thickness of the formed SnO ₂ thin film 12 was about 500 nm.

As shown in the conceptual diagram of the apparatus of FIG. 1, while performing the above-mentioned film formation, a laser beam 14 is emitted from a laser light source 13 from one side surface of a transport tube 8 made of a transparent material, and the other side thereof is irradiated. The light transmittance was measured by detecting the intensity of the laser light transmitted to the side surface with the light receiving element 15. As is clear from the relationship between the light transmittance of the laser beam in the blowing gas and the content rate of the solution fine particles shown in FIG. 4, the higher the light transmittance, the more the solution fine particles in the blowing gas in the transport pipe. The content will be low. The optimum content of the solution particles for forming a film is 145 to 150 mg / liter, and the corresponding laser beam transmittance is 34 to 3
8%. The content of the solution fine particles in the blowing gas detected from the measured value of the light transmittance is fed back to the output controller 16 of the ultrasonic oscillator so that the content of the solution fine particles falls within the range of the optimum value. Then, the input voltage to the ultrasonic transducer 2 was increased or decreased.

FIG. 5 shows a standard correspondence relationship between the input voltage to the ultrasonic vibrator and the content of solution particles in the blowing gas at a solution temperature of 25 ° C. From FIG. 5, it can be seen that the higher the input voltage to the ultrasonic oscillator, the higher the content of the solution particles, and the optimum input voltage is in the vicinity of 39.5 to 40V. However, the quantitative relationship as shown in FIG. 5 is not always maintained due to changes in solution temperature and solution volume during thin film formation, variations in the characteristics of ultrasonic transducers, and changes over time.
It changes every moment. Therefore, when the input voltage is simply fixed to the optimum voltage to form a thin film, the content of the solution particles cannot be maintained within the optimum value range. In this embodiment,
The content of solution fine particles is constantly measured during thin film formation, and when the content is insufficient, the input voltage is increased, and when the content is excessive, the input voltage is lowered to maintain the content of the solution fine particles in the optimum value range. While forming the film.

Comparative Example 1 37 is carried out in the same manner as in Example 1 except that the input voltage to the ultrasonic vibrator 2 is fixed at 40V.
A sheet of SnO ₂ thin film 12 was formed.

3 each formed in Example 1 and Comparative Example 1
The sheet resistance was measured for seven SnO ₂ thin film samples.
FIG. 7 shows the sheet resistance distribution of Example 1, and FIG. 6 shows the sheet resistance distribution of Comparative Example 1. The variation width in the case of Example 1 is 10
Since it was 14 Ω / □, and there was less variation compared with 9 to 15 Ω / □ in the case of Comparative Example 1, it was confirmed that the SnO ₂ thin film of stable quality was obtained in Example 1. At the same time, since the surface resistance is proportional to the film thickness, it can be seen that in Example 1, the variation width of the film thickness is effectively reduced.

Example 2 With the thin film forming apparatus shown in FIG. 2, the content of the decomposition gas of the source material contained in the exhaust gas 20 is measured and the output of the ultrasonic transducer 2 is controlled according to the measured value. , CdS thin film 12 was formed. As the source material solution 3, cadmium dibutyldithiocarbamate 20
Ultrasonic transducer 2 a solution of g in 80 g of toluene
The film-forming substrate 11 having a frequency of 1 MHz and a SnO ₂ thin film formed on a 100 mm square glass substrate by the method of Example 1 is used as the film-forming substrate 11 at a heating temperature of 450.
The film forming time per sheet at 60 ° C. was 60 seconds. Nitrogen gas was used as the carrier gas 6, and the flow rate was 10 liters / minute. After the film formation on one film formation substrate 11 is completed,
Immediately after that, the subsequent film-forming substrate was supplied to continuously form 49 films. The standard film thickness of the formed CdS thin film 12 was about 100 nm.

As shown in the conceptual diagram of the apparatus of FIG. 2, the exhaust gas 2 is emitted from the infrared light source 24 while the thin film is formed.
An infrared ray 21 having an absorption wavelength peculiar to the decomposed gas in 0 is made incident from one side surface of an exhaust pipe 22 made of a transparent material, and the intensity of the infrared ray 21 transmitted to the other side surface is received by an infrared light receiving element 23. It was detected and the light transmittance was measured. In this case, the main component of the decomposition gas contained in the exhaust gas 20 after the source material cadmium dibutyldithiocarbamate is thermally decomposed to form the CdS thin film 12 is carbon disulfide (CS).
₂ ) and the absorption wavelength peculiar to this gas is 197n
The light transmittance of infrared rays having a wavelength of m was measured.

From the measured values of the light transmittance, the concentration of the CS ₂ gas in the exhaust gas was obtained based on the relationship between the light transmittance shown in FIG. 8 and the content of the CS ₂ gas in the exhaust gas. The optimum content of CS ₂ gas in the exhaust gas is 1.5 to
It is 1.6 mg / liter, and from FIG. 8, the light transmittance corresponding to this is 36 to 38%. The content of CS ₂ gas in the exhaust gas obtained from the measured value of the light transmittance is fed back to the output controller 16 of the ultrasonic transducer,
The input voltage to the ultrasonic transducer 2 was increased or decreased so that the content of CS ₂ gas in the exhaust gas was within the range of the optimum value.

FIG. 9 shows a standard correspondence relationship between the input voltage to the ultrasonic transducer and the content of CS ₂ gas in the exhaust gas at a solution temperature of 25 ° C. It can be seen from FIG. 9 that the higher the input voltage to the ultrasonic transducer, the higher the content of CS ₂ gas in the exhaust gas, and the optimum input voltage is in the vicinity of 39.5 to 40V. However, in practice, the quantitative relationship as shown in FIG. 9 changes momentarily due to changes in the solution temperature and solution amount during thin film formation, variations in the characteristics of the ultrasonic oscillator, changes over time, and the like.
Therefore, when the film is formed by simply fixing the input voltage to the above-mentioned optimum voltage, the content of CS ₂ gas cannot be maintained in an appropriate range, and at the same time, the content of solution fine particles in the gas for spraying falls within the optimum value range. Can't keep up.

In this embodiment, as described above, the content of CS ₂ gas in the exhaust gas is constantly measured, and when the content of CS ₂ gas is insufficient, the input voltage is increased, and when it is excessive, the input voltage is decreased. By doing so, CS ₂ in the exhaust gas is constantly
The gas content was maintained in an appropriate range, and the film formation was performed while maintaining the content of the solution fine particles in the optimum value range.

Comparative Example 2 49 is carried out in the same manner as in Example 1 except that the input voltage to the ultrasonic vibrator 2 is fixed at 40V.
A sheet of CdS thin film was formed.

Each of 4 formed in Example 2 and Comparative Example 2
The light transmittance at a wavelength of 400 nm was measured for the nine CdS thin film samples. FIG. 11 shows the light transmittance distribution of Example 2, and FIG. 10 shows the light transmittance distribution of Comparative Example 2. The variation range of the light transmittance in the case of Example 2 is 12 to 22%, which is smaller than the variation range of 8 to 22% in the case of Comparative Example 2. Therefore, in Example 2, a CdS thin film of stable quality was obtained. It was confirmed that it was obtained. Further, as shown in FIG. 12, since the film thickness of the CdS thin film corresponds to this light transmittance, it can be seen that in Example 2, the variation width of the film thickness is also effectively reduced.

Example 3 The concentration of the solvent vapor of the source material solution contained in the exhaust gas is measured, and the output of the ultrasonic transducer is controlled according to the measured value by the thin film forming apparatus of FIG. _Two thin films were formed. The thin film formation conditions were the same as in Example 1 except that the output of the ultrasonic transducer was controlled according to the measured value of the vapor concentration of the solvent (water) contained in the exhaust gas, and the standard film thickness was about 37 100-nm CdS thin film formation was performed continuously.

As shown in the conceptual diagram of the apparatus in FIG. 3, the water vapor concentration in the exhaust gas 20 was measured by the solvent vapor concentration sensor 25 (ceramic humidity sensor) while forming the thin film. This measurement was performed by installing the ceramic humidity sensor 25 at a position where the temperature of the exhaust gas 20 gradually cooled in the exhaust pipe 26 becomes 80 ° C. The measured relative humidity value at 80 ° C is used as the output controller 16 of the ultrasonic transducer.
To perform a feedback control so that the concentration of water vapor in the exhaust gas 20 becomes constant.

Input voltage to the ultrasonic transducer and exhaust gas 8
Regarding the relationship with the relative humidity at 0 ° C., there is a standard tendency as shown in FIG. 13, and the water vapor concentration increases as the input voltage increases. In this case, the optimum relative humidity is 75-80%, and the optimum input voltage is 39.5.
It is around -40V. However, in reality, the quantitative relationship as shown in FIG. 13 changes momentarily due to changes in the solution temperature and solution amount during thin film formation, variations in the characteristics of the ultrasonic oscillator, and changes over time. Therefore, when the film is formed by simply fixing the input voltage to the optimum voltage, the water vapor concentration cannot be maintained within an appropriate range, and at the same time, the content of solution particles in the blowing gas cannot be maintained within the optimum value range. In this embodiment, as described above, the water vapor concentration in the exhaust gas is constantly measured as the relative humidity at 80 ° C., and when the water vapor concentration is lower than the optimum value, the input voltage is increased, and when the water vapor concentration is high, the input voltage is lowered. The water vapor concentration in the exhaust gas was constantly maintained in an appropriate range, and a thin film was formed while maintaining the content of the solution particles in the optimum value range.

37 sheets of SnO ₂ each formed in Example 3
The results of measuring the sheet resistance of the thin film sample are shown in FIG. The variation width in the case of Example 3 is 10 to 15 Ω / □, which is smaller than the variation width of 9 to 15 Ω / □ in the case of Comparative Example 1 in FIG. 6, confirming the effect of the present invention. At the same time, since the surface resistance is proportional to the film thickness, it can be seen that the variation width of the film thickness is reduced in Example 3.

Although the formation of the CdS thin film among the metal sulfide thin films has been described in detail in the second embodiment, the formation of the ZnS thin film and the mixed crystal thin film of CdS and ZnS is also the same as the second embodiment. The same experiment was conducted, and the effect of the present invention with the same tendency was confirmed. In these cases, Zn
Zinc dibutyldithiocarbamate for forming S thin film 20
Using a source material solution in which g is dissolved in 80 g of toluene,
To form a mixed crystal thin film of CdS and ZnS, a source material solution prepared by dissolving 10.5 g of cadmium dibutyldithiocarbamate and 9.5 g of zinc dibutyldithiocarbamate in 80 g of toluene was used. Other conditions were the same as in Example 2. I conducted an experiment.

[0042]

According to the present invention, the content of the solution fine particles of the source material solution in the blowing gas, the content of the decomposition gas of the source material in the exhaust gas after film formation, or the source material solution in the exhaust gas The solvent vapor concentration of is constantly measured during thin film formation, and by controlling the output of the ultrasonic oscillator so that the measured value becomes an appropriate value, a thin film of metal oxide or metal sulfide is formed. The thickness can be made uniform and the characteristics can be stabilized.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing the configuration of an apparatus used in an embodiment of the present invention for controlling the output of an ultrasonic transducer so that the content of solution fine particles in a blowing gas becomes an appropriate value.

FIG. 2 is a conceptual diagram showing a configuration of an apparatus used in another embodiment of the present invention for controlling the output of the ultrasonic transducer so that the decomposition gas content in the exhaust gas becomes an appropriate value.

FIG. 3 is a conceptual diagram showing the configuration of an apparatus used in yet another embodiment of the present invention for controlling the output of the ultrasonic transducer so that the concentration of solvent vapor in exhaust gas becomes an appropriate value.

FIG. 4 is a diagram showing the relationship between the light transmittance of laser light and the content of solution fine particles in a gas for spraying when forming a tin dioxide thin film.

FIG. 5 is a diagram showing a standard relationship between the content of solution fine particles in a blowing gas and the input voltage to an ultrasonic oscillator in the production of a tin dioxide thin film.

6 is a distribution diagram of sheet resistance of the tin dioxide thin film of Comparative Example 1. FIG.

FIG. 7 is a distribution diagram of sheet resistance of the tin dioxide thin film of Example 1.

FIG. 8 is a diagram showing the relationship between the infrared light transmittance in exhaust gas and the CS ₂ gas content in the film formation of a cadmium sulfide thin film.

FIG. 9 is a diagram showing a standard relationship between the content of CS ₂ gas in the exhaust gas and the input voltage to the ultrasonic vibrator in the film formation of the cadmium sulfide thin film.

10 is a distribution diagram of light transmittance of the cadmium sulfide thin film of Comparative Example 2. FIG.

FIG. 11 is a distribution diagram of the light transmittance of the cadmium sulfide thin film of Example 2.

FIG. 12 is a diagram showing the relationship between the film thickness of a cadmium sulfide thin film and the light transmittance.

FIG. 13 is a diagram showing a standard relationship between the relative humidity of exhaust gas in a tin dioxide film formation and the input voltage to an ultrasonic transducer.

FIG. 14 is a distribution diagram of sheet resistance of the tin dioxide thin film of Example 3.

[Explanation of symbols]

1 atomization container 2 Ultrasonic transducer 3 Source material solution 4 Solution particles 5 introduction pipes 6 carrier gas 7 Spraying gas 8 transport pipes 9 heater 10 heating plate 11 Film forming substrate 12 thin film 13 Laser light source 14 laser light 15 Light receiving element 16 Ultrasonic transducer output controller 17 Support 20 exhaust gas 21 infrared 22 Exhaust pipe 23 Infrared receiver 24 infrared light source 25 Solvent vapor concentration sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Takeshi Hibino Takeshi Hibino 1-1, Matsushita-cho, Moriguchi-shi, Osaka Matsushita Battery Industrial Co., Ltd. (56) Reference JP-A-61-244025 (JP, A) JP-A-7 -150361 (JP, A) JP 2-179880 (JP, A) JP 8-41646 (JP, A) JP 61-166978 (JP, A) JP 8-316247 (JP, A) ) JP-A-11-87747 (JP, A) JP-A-2000-44238 (JP, A) JP-A-8-239240 (JP, A) JP-A-10-317144 (JP, A) JP-A-7-126852 (JP, A) JP 7-54141 (JP, A) Special table 6-508659 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 18/12 C01G 9 / 08 C01G 11/02 C01G 19/02 C23C 16/44

Claims (12)

(57) [Claims] 1. A source material solution in which a source material is dissolved in a solvent is atomized by an ultrasonic oscillator, and a spraying gas in which the atomized fine particles of the solution are contained in a carrier gas,
In the thin film forming method of spraying on the surface of the pre-heated film-forming substrate, thermally decomposing the source material in the fine particles to form a metal oxide or metal sulfide thin film on the film-forming substrate, A method of forming a thin film, comprising: measuring the content of the fine particles in a working gas, and controlling the output of the ultrasonic transducer so that the measured value becomes an appropriate value. 2. The thin film forming method according to claim 1, wherein the content of the fine particles in the blowing gas is measured by the light transmittance of the blowing gas. 3. A source material solution in which a source material is dissolved in a solvent is atomized by an ultrasonic oscillator, and a spraying gas in which fine particles of the atomized solution are contained in a carrier gas is used.
In a thin film forming method of spraying on the surface of a pre-heated film-forming substrate to thermally decompose the source material in the fine particles to form a metal oxide or metal sulfide thin film on the film-forming substrate, exhaust gas A method of forming a thin film, comprising: measuring a content of a decomposed gas of the source material therein, and controlling the output of the ultrasonic oscillator so that the measured value becomes an appropriate value. 4. A source material solution in which a source material is dissolved in a solvent is atomized by an ultrasonic vibrator, and a spraying gas in which fine particles of the atomized solution are contained in a carrier gas,
In a thin film forming method of spraying on the surface of a pre-heated film-forming substrate to thermally decompose the source material in the fine particles to form a metal oxide or metal sulfide thin film on the film-forming substrate, exhaust gas A thin film forming method, characterized in that the vapor concentration of the solvent therein is measured, and the thin film is formed while controlling the output of the ultrasonic oscillator so that the measured value becomes an appropriate value. 5. The thin film forming method according to claim 1, wherein the metal oxide is tin dioxide. 6. The thin film forming method according to claim 1, wherein the metal sulfide is cadmium sulfide, zinc sulfide, or a mixed crystal of cadmium sulfide and zinc sulfide. 7. A means for atomizing a source material solution in which a source material is dissolved in a solvent by an ultrasonic oscillator, a means for containing fine particles of the atomized solution in a carrier gas to obtain a gas for spraying, and A means for heating the film-forming substrate is provided, and the gas for blowing is sprayed onto the surface of the film-forming substrate that has been heated in advance, so that the source material in the fine particles is thermally decomposed and metal oxide is formed on the film-forming substrate. A thin film forming apparatus for forming a thin film of a metal or metal sulfide, measuring the content of the fine particles in the blowing gas, and controlling the output of the ultrasonic vibrator so that the measured value becomes an appropriate value. An apparatus for forming a thin film, comprising: 8. The thin film forming apparatus according to claim 7, wherein the content of the fine particles in the blowing gas is measured by the light transmittance of the blowing gas. 9. A means for atomizing a source material solution in which a source material is dissolved in a solvent with an ultrasonic oscillator, a means for containing fine particles of the atomized solution in a carrier gas to obtain a blowing gas, and A means for heating the film-forming substrate is provided, and the gas for blowing is sprayed onto the surface of the film-forming substrate that has been heated in advance, so that the source material in the fine particles is thermally decomposed and metal oxide is formed on the film-forming substrate. A thin film forming apparatus for forming a thin film of a metal or metal sulfide, measuring the content of decomposed gas of the source material in exhaust gas, and outputting the ultrasonic transducer so that the measured value becomes an appropriate value. A thin film forming apparatus having a means for controlling. 10. A means for atomizing a source material solution in which a source material is dissolved in a solvent by an ultrasonic oscillator, a means for containing fine particles of the atomized solution in a carrier gas to obtain a gas for spraying, and A means for heating the film-forming substrate is provided, and the gas for blowing is sprayed onto the surface of the film-forming substrate that has been heated in advance, so that the source material in the fine particles is thermally decomposed and metal oxide is formed on the film-forming substrate. Thin film forming apparatus for forming a thin film of a metal or metal sulfide, means for measuring the vapor concentration of the solvent in the exhaust gas, and controlling the output of the ultrasonic transducer so that the measured value becomes an appropriate value. A thin film forming apparatus comprising: 11. The thin film forming apparatus according to claim 7, wherein the metal oxide is tin dioxide. 12. The thin film forming apparatus according to claim 7, wherein the metal sulfide is cadmium sulfide, zinc sulfide, or a mixed crystal of cadmium sulfide and zinc sulfide.