JP2013129867A - Device and method for forming thin film, and method for manufacturing thin-film solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for forming a thin film, capable of forming a thin film with a uniform film quality at a high rate.SOLUTION: A thin film forming device 100 has a sprayer 4 for spraying a mist 9 onto a substrate 1, a cooling means for cooling a raw material solution 5 in the sprayer 4, and a heating unit 3 for heating the mist 9. A vertical distance Lb from a lower end of the sprayer 4 to an upper surface of the substrate 1 is 1/2 La to La, where La is a vertical distance from the upper surface of the substrate 1 to a top end of the heating unit 3.

Description

  The present invention relates to a thin film deposition apparatus, a thin film deposition method, and a method for manufacturing a thin film solar cell.

  Thin films such as alkali barrier layers and transparent conductive films are widely used in the fields of semiconductors, displays, solar cells and the like. Such a transparent conductive film is made of a metal oxide such as STO (strontium titanate) or ITO (Sn-doped indium oxide), and generally used a sputtering method, a vapor deposition method, or an organometallic compound. The film is formed by a metal organic chemical vapor deposition method or the like.

  However, since the sputtering method or the vapor deposition method needs to form a film by a vacuum process, equipment for forming and maintaining a vacuum atmosphere such as a vacuum vessel is required. On the other hand, in the organometallic chemical vapor deposition method, since the organometallic compound used as a raw material has explosiveness and toxicity, it is necessary to provide an advanced safety design for the entire thin film deposition system, for example, by installing an exhaust gas treatment device. . For the above reasons, it is difficult to reduce the costs of the sputtering method, the vapor deposition method, and the metal organic chemical vapor deposition method.

  Therefore, a mist method has been proposed as a film forming method different from the conventional one. The mist method is a film forming method for forming a film by atomizing a solvent containing a raw material metal as a solute and spraying it on a substrate.

  Since the mist method can form a film at atmospheric pressure, a manufacturing facility such as a vacuum vessel or pumps is unnecessary. In addition, since no dangerous substance such as an organometallic compound is used, the film forming apparatus itself has a simple configuration and can be formed at low cost. The mist method having such merits is expected as a new method to replace the conventional thin film forming method.

  For example, Patent Documents 1 and 2 can be cited as prior art documents disclosing such film formation means by the mist method. In Patent Document 1, first, a raw material solution containing a metal oxide is atomized by ultrasonic vibration to generate mist. The mist is heated and then sprayed onto the substrate to form a dense and homogeneous thin film.

  Moreover, in patent document 2, in order to raise the vaporization rate of the mist sprayed from a spray nozzle, the spray nozzle for supplying carrier gas to the vicinity of the spray nozzle is provided. The carrier gas is sprayed in an oblique direction at an angle of about 10 to 30 ° with respect to the mist spraying direction. By spraying the carrier gas onto the mist in this way, the mist is disturbed to generate a swirling flow, and the mist can be dispersed.

JP 2007-046155 A (publication date: February 22, 2007) JP 2004-107729 A (publication date: April 8, 2004)

  In the above prior art, the substrate on which the mist is sprayed is heated in order to evaporate the solvent contained in the mist. This heating generates an upward airflow (thermal convection) in a direction opposite to the direction toward the substrate. . There is a problem that part of the mist does not reach the substrate due to the rising airflow, and the film forming rate is lowered.

  In order to prevent such a problem, increasing the spray pressure of the mist or increasing the flow rate of the carrier gas is performed. However, when the spray pressure is increased, there is a problem that the life of the spray nozzle is shortened. When the flow rate of the carrier gas is increased, the mist is stably supplied to the substrate because the average particle diameter of the mist is decreased. The problem of being unable to do so arises. In addition, when the spray nozzle is heated in a heating furnace, the solvent contained in the raw material solution evaporates, the concentration of the raw material solution changes, or the spray nozzle becomes clogged, making it impossible to form a uniform film. .

  The present invention has been made in view of the above-described situation, and an object of the present invention is to provide a thin film forming apparatus and a thin film forming apparatus capable of forming a thin film having a uniform film quality at a high film forming rate. It is to provide a method.

  In order to solve the above problems, a thin film deposition apparatus according to the present invention includes a sprayer that changes a raw material solution into a mist and sprays the mist onto a substrate from a spray port, and the substrate is sprayed from the sprayer. A thin film forming apparatus for forming a thin film, comprising: a cooling unit for cooling the raw material solution in the sprayer; and a heating unit for heating the mist. A vertical distance from the upper surface of the substrate to the upper end of the heating unit, where La is the vertical distance from the upper surface of the substrate to the upper end of the heating unit. The direction distance Lb is ½ La to La.

  In order to solve the above problems, a thin film deposition method according to the present invention is a thin film deposition method for depositing a thin film on a substrate, the cooling step of cooling a raw material solution in a sprayer, A spraying step of changing the raw material solution into mist by a sprayer and spraying the mist onto the substrate from a spraying port of the sprayer; and a heating step of heating the mist by a heating unit, It is provided in the lower part inside and opposed to the spray port, and when the vertical distance from the upper surface of the substrate to the upper end of the heating unit is La, the vertical direction from the spray port to the upper surface of the substrate is The distance Lb is ½ La to La.

  According to said structure, since the raw material solution in a sprayer is cooled, the solvent contained in the raw material solution in a sprayer becomes difficult to volatilize, and the density | concentration of a raw material solution can be kept uniform. For this reason, it is possible to form a thin film while keeping the concentration of the raw material solution constant, thereby stabilizing the properties of the thin film. Further, when the distance Lb is 1/2 La to La, mist can be stably generated, and the mist can reach the upper surface of the substrate without generating thermal convection. Therefore, it is possible to provide a thin film forming apparatus and a thin film forming method capable of forming a thin film having a uniform film quality at a high film forming rate.

  In the thin film deposition apparatus according to the present invention, it is more preferably 2/3 La to 5/6 La.

  In the thin film deposition apparatus and the thin film deposition method according to the present invention, the thin film is preferably a transparent conductive film, and the temperature inside the heating unit is preferably 500 to 600 ° C.

  In the thin film deposition apparatus according to the present invention, the temperature inside the heating unit is more preferably 530 to 570 ° C.

  According to said structure, a transparent conductive film can be formed into a film with a high film-forming rate.

  In the thin film deposition apparatus according to the present invention, the substrate is preferably movable by a moving mechanism.

  In the thin film forming method according to the present invention, it is preferable that in the spraying step, the substrate is moved in a direction substantially perpendicular to a direction in which the mist is sprayed.

  In the film thickness distribution when the thin film is formed on the substrate with the substrate fixed without moving in the horizontal direction, the film thickness is not uniform in the region formed by the mist flowing parallel to the substrate surface. . On the other hand, according to the above configuration, since the film formation is performed while moving the substrate, a thin film having a uniform film quality can be formed on the entire substrate.

  In the thin film deposition apparatus according to the present invention, it is preferable that the cooling means cools the raw material solution in the sprayer to a boiling point or lower of the raw material solution.

  According to said structure, volatilization of the solvent contained in a raw material solution can be controlled appropriately, and clogging of a spraying port can be prevented.

  In the thin film deposition apparatus according to the present invention, it is preferable that the cooling means is a pipe provided around the sprayer, and the raw material solution in the sprayer is water-cooled by the pipe.

  According to said structure, a raw material solution can be cooled easily.

  The method for manufacturing a thin film solar cell according to the present invention includes a first film forming step of forming a thin film of an alkali barrier layer on a glass substrate, and the first film forming step includes each of the above thin film forming methods. It is characterized by including steps.

  The method for producing a thin film solar cell according to the present invention includes a first film forming step of forming a thin film of an alkali barrier layer on a glass substrate, and a second film forming a thin film of a transparent conductive film on the alkali barrier layer. And at least one of the first film forming step and the second film forming step includes each step of the thin film forming method.

  According to said structure, since a transparent conductive film and / or an alkali barrier layer can be uniformly formed on a glass substrate, a high performance thin film solar cell can be manufactured.

  As described above, the thin film deposition apparatus according to the present invention has a sprayer that changes the raw material solution into mist and sprays the mist onto the substrate from the spray port, and forms a thin film on the substrate by spraying from the sprayer. A thin film forming apparatus for forming a film, comprising: a cooling unit for cooling the raw material solution in the sprayer; and a heating unit for heating the mist, wherein the substrate is provided inside the heating unit. A vertical distance Lb from the spray port to the upper surface of the substrate is defined as La, which is provided below and opposed to the spray port, and La is the vertical distance from the upper surface of the substrate to the upper end of the heating unit. Is 1/2 La to La. The thin film deposition method according to the present invention is a thin film deposition method for depositing a thin film on a substrate, the cooling step of cooling the raw material solution in the sprayer, and the mist of the raw material solution by the sprayer. And the spraying step of spraying the mist onto the substrate from the spraying port of the sprayer, and the heating step of heating the mist by a heating unit, the substrate being disposed in the spraying port below the heating unit. The vertical distance Lb from the spray port to the upper surface of the substrate is ½ La, where La is the vertical distance from the upper surface of the substrate to the upper end of the heating unit. ~ La. Therefore, it is possible to provide a thin film forming apparatus and a thin film forming method capable of forming a thin film having a uniform film quality at a high film forming rate.

It is sectional drawing which shows typically an example of the thin film film-forming apparatus of this invention. It is sectional drawing which shows typically the film-forming line incorporating the said thin film film-forming apparatus. It is a figure which shows the film thickness distribution of the thin film formed on the board | substrate with the said thin film film-forming apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals represent the same or corresponding parts. In addition, dimensional relationships such as length, width, thickness, and depth are changed as appropriate for clarity and simplification of the drawings, and do not represent actual dimensional relationships.

[Configuration of thin film deposition system]
FIG. 1 is a cross-sectional view schematically showing a thin film deposition apparatus 100 as an example of the thin film deposition apparatus of the present invention. The thin film forming apparatus 100 is for forming a thin film (not shown) on the substrate 1, and includes a heating unit 3 and a spraying device 6.

<Heating unit 3>
The heating unit 3 is a rectangular parallelepiped container, and the inside thereof is held at a high temperature. A loading table 2 is provided below the heating unit 3. A substrate 1 is mounted on the mounting table 2, and the substrate 1 is heated by the heating unit 3 during film formation. The mounting table 2 has a moving mechanism (not shown), and forms a thin film on the substrate while moving uniaxially in the direction of the film forming surface of the substrate 1. That is, the loading table 2 including the substrate 1 and the moving mechanism are accommodated in the heating unit 3. It should be noted that the loading table 2 does not necessarily move uniaxially in the film formation surface direction during film formation, and the loading table 2 may be stopped during film formation.

  A hole is formed in the upper surface of the heating unit 3, and a spraying device 6 is fitted in the hole. Thereby, the lower part of the spraying device 6 is covered with the heating unit 3.

<Spraying device 6>
The spraying device 6 includes a housing having a gas inlet 7 and an exhaust 10 and a sprayer 4 attached to the inside of the housing.

<Nebulizer 4>
The sprayer 4 changes the raw material solution 5 into the mist 9 and sprays the mist 9 from the nozzle 8 onto the substrate 1, and the mist 9 can be generated by ultrasonic atomization or spray spraying. Here, when generating mist using ultrasonic atomization, it is preferable to generate mist by an ultrasonic transducer. Since the ultrasonic vibrator can spray mist having a relatively uniform average particle diameter, there is an advantage that the mists are less likely to aggregate.

  The nozzle 8 is attached to the tip of the sprayer 4 and is constituted by, for example, a two-fluid spray nozzle. In this case, the mist 9 is formed by mixing the compressed air and the raw material solution in the nozzle 8. The number of sprayers 4 may be changed according to the spray amount per unit time required for the tact time, or may be changed according to the film formation rate required for film formation.

  Here, “mist” refers to a liquid in which droplets having an average particle diameter of 0.1 μm or more and 100 μm or less are dispersed in a gas. As the average particle diameter of such mist, a value calculated by a liquid immersion method is adopted.

  Further, a cooling means (not shown) is provided in the sprayer 4.

<Cooling means>
In the present embodiment, the cooling means is provided for cooling the raw material solution 5 in the sprayer 4. By cooling the raw material solution 5 in the sprayer 4 by such cooling means, nozzle clogging at the tip of the sprayer 4 can be prevented.

  From the viewpoint of preventing nozzle clogging, it is preferable to cool the raw material solution 5 in the sprayer 4 to a temperature not higher than the boiling point of the raw material solution 5. By cooling the raw material solution 5 to such a temperature, the solvent in the raw material solution 5 becomes difficult to volatilize. Therefore, the concentration of the raw material solution 5 can be kept constant and nozzle clogging at the tip of the sprayer 4 can be prevented.

  It is more preferable that the cooling means is for cooling the raw material solution 5 in the sprayer 4 to about room temperature.

  The cooling means may cool the raw material solution by air cooling, may cool the raw material solution by water cooling, or may use both in combination. The cooling method by air cooling can include a fan, and the cooling means by water cooling can include piping provided around the sprayer.

  Thus, by cooling the raw material solution 5 in the sprayer 4 by the cooling means, the solvent contained in the raw material solution 5 is less likely to evaporate, and thus the nozzle of the sprayer 4 can be blocked and the sprayer 4 can be prevented from being deformed. .

<Raw material solution 5>
As the raw material solution 5, it is preferable to use an inorganic material chloride or organometallic compound selected from the group consisting of zinc, tin, indium, cadmium and strontium in a solvent. Examples of the solvent used for the raw material solution 5 include water, methanol, ethanol, and butanol. Examples of the raw material solution 5 include an aqueous solution containing zinc acetate, an aqueous solution containing indium tin oxide, and an aqueous solution containing tin oxide. The concentration of the raw material solution 5 is not particularly limited, but it is generally preferable to use a solution containing a chloride or an organometallic compound at a concentration of 0.1 to 3 mol / L.

<Position relationship between substrate 1 and sprayer 4>
In the present embodiment, when the vertical distance from the upper surface of the substrate 1 to the upper end of the heating unit 3 is La, the vertical distance Lb from the lower end (spray port) of the sprayer 4 to the upper surface of the substrate 1 is 1 / 2La to La. Thus, by properly setting the spray pressure and the exhaust gas flow rate, the mist 9 can be generated stably, and the mist 9 can reach the upper surface of the substrate 1 without generating thermal convection. More preferably, the vertical distance Lb from the lower end of the sprayer 4 to the upper surface of the substrate 1 is 2/3 La to 5/6 La.

  If the distance Lb is less than ½ La, heating of the sprayed raw material solution 5 is insufficient, and it takes time to vaporize the solvent contained in the raw material solution 5, which is not preferable. On the other hand, when the distance Lb exceeds La, the ratio of the high temperature region between the spray port of the nozzle 8 to which the mist 9 is sprayed and the substrate 1 increases. And the gravity and inertial force of the mist 9 are weakened. Thereby, it becomes difficult for the mist 9 to reach the substrate 1, and the deposition rate of the thin film tends to decrease.

<Temperature in the heating unit 3>
In addition, the temperature in the heating unit 3 is different depending on the thin film to be formed, so that it is difficult to uniformly determine the optimum temperature. For example, when forming a transparent conductive film, the heating unit 3 The film is preferably formed at a temperature of 500 to 600 ° C., more preferably 530 to 570 ° C.

  In addition, since the solvent contained in the mist 9 becomes difficult to volatilize when the temperature in the heating part 3 is less than 500 degreeC, the film-forming rate of a transparent conductive film will fall remarkably. On the other hand, when the temperature in the heating unit 3 exceeds 600 ° C., the solvent in the mist 9 volatilizes before the mist 9 reaches the substrate 1, and the mist 9 hardly reaches the surface of the substrate 1.

Here, the “transparent conductive film” is required to be transparent and conductive, and is made of, for example, ITO or STO. On the other hand, the “alkali barrier layer” is provided to prevent the alkali component contained in the substrate from being released outside the substrate. The alkali barrier layer does not necessarily have to be provided on the surface of the substrate 1 when the substrate 1 does not contain an alkali component or contains a slight amount of an alkali component. Such an alkali barrier layer is made of SiO _2. It is preferable.

<Summary of configuration>
As described above, as shown in FIG. 1, the thin film deposition apparatus 100 includes the sprayer 4 that changes the raw material solution 5 into the mist 9 and sprays the mist 9 onto the substrate 1 from the spraying port. Is a thin film deposition apparatus for depositing a thin film (not shown) on the substrate 1 by spraying from the substrate, and has a cooling means for cooling the raw material solution 5 in the sprayer 4 and a heating unit 3. 1 is provided below the inside of the heating unit 3 so as to be opposed to the spraying port, and when the vertical distance from the upper surface of the substrate 1 to the upper end of the heating unit 3 is La, the substrate 1 The distance Lb in the vertical direction to the upper surface of is ½ La to La.

  According to said structure, since the raw material solution 5 in the sprayer 4 is cooled, the solvent contained in the raw material solution 5 in the sprayer 4 becomes difficult to volatilize, and the density | concentration of the raw material solution 5 can be kept uniform. For this reason, it is possible to form a thin film while keeping the concentration of the raw material solution 5 constant, thereby stabilizing the properties of the thin film. Further, when the distance Lb is 1/2 La to La, the mist 9 can be stably generated, and the mist 9 can reach the upper surface of the substrate 1 without generating thermal convection. Therefore, a thin film having a uniform film quality can be formed at a high film formation rate.

[Operation of Thin Film Deposition Apparatus 100]
Next, the operation of the thin film deposition apparatus 100 will be described.

  In the thin film deposition apparatus 100, first, when compressed air is introduced from the gas inlet 7 into the sprayer 4, the sprayer 4 sucks up the raw material solution 5 from the thin film material solution tank, changes the raw material solution 5 into the mist 9, and the sprayer 4. Mist 9 is ejected from nozzle 8 at the tip. As the compressed air, for example, nitrogen, oxygen, hydrogen, and a mixed gas thereof can be used.

  On the upper surface of the substrate 1, in addition to the film formation of the mist 9 flowing in the vertical direction by the sprayer 4, film formation in the horizontal direction is also performed by the mist 9 flowing in the horizontal direction parallel to the direction in which the substrate 1 moves. Excess spray mist that has not been formed is discharged to the outside through the exhaust port 10 and the abatement device (not shown). As described above, in the thin film deposition apparatus 100, the carrier gas is not used, and the gas inlet 7 and the outlet 10 are almost directly connected as shown by the arrows in FIG. The amount of compressed air introduced into the sprayer 4 and the exhaust amount exhausted from the sprayer 4 can be set as appropriate.

[Deposition line 200]
FIG. 2 is a cross-sectional view schematically showing a film forming line 200 in which the thin film forming apparatus 100 of this embodiment is incorporated. In the film forming line 200, the substrate 1 is transported to the right direction in the drawing at a rate of, for example, 10 mm / sec by a belt conveyor (moving mechanism), and is put into the heating unit 17 and stopped. The substrate 1 heated by the heating unit 17 is then introduced into the film forming unit (lower side in FIG. 1) of the thin film forming apparatus 100. In this film forming section, a thin film such as an alkali barrier layer or a transparent conductive film is formed on the substrate 1. This film formation may be performed while moving the substrate 1 in a direction substantially perpendicular to the direction in which the mist 9 is sprayed. Thereafter, the substrate 1 is introduced into the cooling unit 18 and stops. When the substrate 1 and the thin film are cooled in the cooling unit 18, the substrate 1 on which the thin film is formed is completed. The substrate 1 on which the thin film is formed is taken out from the rightmost takeout port in FIG.

[Thickness distribution]
In the thin film deposition apparatus 100, as shown in FIG. 1, the region where the thin film is deposited by the mist 9 in the direction perpendicular to the substrate 1 (first deposition region) is parallel to the direction in which the substrate 1 moves. There is a region (second film formation region) where the film is formed by the mist 9 flowing in the horizontal direction. Here, the film thickness distribution of the thin film when the transparent conductive film was formed on the substrate 1 in the state where the substrate 1 was fixed without moving in the horizontal direction using the thin film deposition apparatus 100 was examined. The result is shown in FIG.

  FIG. 3 is a graph showing the film thickness distribution of the thin film formed on the substrate 1. The horizontal axis is the distance (mm) from the right end (exhaust port 10 side) of the substrate 1, and the vertical axis is the film thickness of the thin film.

  As shown in FIG. 3, a thin film having a thickness of about 1 μm is uniformly formed in a region (first film formation region) whose distance from the right end of the substrate 1 is 300 to 500 mm. On the other hand, in the region where the distance from the right end of the substrate 1 is 100 to 300 mm (second film formation region), the film thickness of the thin film becomes primary as the distance from the first film formation region increases, that is, the closer to the exhaust port 10 side. It turns out that it becomes thin functionally.

[Thin film deposition method]
The thin film deposition method of the present embodiment is a thin film deposition method for depositing a thin film on a substrate, and includes a cooling step for cooling the raw material solution 5 in the sprayer 4 and the mist of the raw material solution 5 by the sprayer 4. 9, and includes a spraying step of spraying the mist 9 onto the substrate 1 from the spraying port of the sprayer 4 and a heating step of heating the mist 9 by the heating unit 3. The substrate 1 is disposed below the inside of the heating unit 3. When the distance in the vertical direction from the upper surface of the substrate 1 to the upper end of the heating unit 3 is La, the vertical distance Lb from the spray port to the upper surface of the substrate 1 is 1 /. It is characterized by being 2La to La.

  In a conventional manufacturing method such as a spray CVD method or a mist CVD method, the raw material solution in the sprayer is heated to cause volatilization of the solvent contained in the raw material solution, thereby changing the concentration of the raw material solution. For this reason, in the conventional film forming method, in order to form a thin film with uniform film quality, adjustment such as addition of a solvent to the raw material solution at an appropriate timing is necessary, and the utilization efficiency of the material is low. In particular, when film formation is performed with a mist CVD apparatus that forms a thin film by spraying mist, the film formation efficiency is significantly reduced.

  In contrast, in the thin film deposition method of the present embodiment, since the raw material solution 5 in the sprayer 4 is cooled by air cooling or water cooling, the solvent contained in the raw material solution 5 in the sprayer 4 is less likely to be volatilized. The concentration of the solution 5 can be kept uniform. For this reason, it is possible to form a thin film while keeping the concentration of the raw material solution 5 constant, so that the performance of the thin film is stabilized, and the film formation cost is reduced and the productivity is improved. Such merit is considered to increase the effect obtained as the area of the substrate increases.

  When forming a transparent conductive film using said thin film forming method, it is preferable to hold | maintain the temperature inside the heating part 3 at 500-600 degreeC.

  In the cooling step of cooling the raw material solution 5 in the sprayer 4, it is preferable to cool the raw material solution 5 in the sprayer 4 to the boiling point of the raw material solution 5 or less. Thereby, volatilization of the solvent contained in the raw material solution 5 can be appropriately controlled.

  The spraying step may be performed while moving the substrate 1 in a direction substantially perpendicular to the direction in which the mist 9 is sprayed. Thus, even if a thin film is formed while moving the substrate 1, the thin film forming method of this embodiment has a manufacturing advantage in that a thin film having uniform characteristics can be formed.

<Application to thin-film solar cells>
When manufacturing a thin film solar cell, a glass substrate is used as the substrate 1, an alkali barrier layer is formed on the glass substrate (first film forming step), and a transparent conductive film is formed on the alkali barrier layer. After that (second film formation step), a semiconductor film and a metal film are formed. As this glass substrate, a soda-lime-silica glass plate that is generally used and inexpensive is generally used.

  This soda lime silica glass plate contains about 10 to 20% by mass of an alkali component such as sodium or potassium, but the alkali component diffuses from the base of the glass substrate to the outside of the glass substrate when used for a long period of time. Thereby, the transparent conductive film formed on the upper part of the glass substrate becomes cloudy, the transparency decreases, the resistance value of the transparent conductive film increases, or the chemical or physical durability decreases. That is, the redox reaction occurs on the surface of the transparent conductive film due to the alkali diffused from the glass substrate, the material constituting the transparent conductive film is altered, and the thin film solar cell itself undergoes electrolysis, thereby degrading the thin film solar cell. To do. In order to prevent such a problem, an alkali barrier layer may be formed on the surface of the glass substrate.

  In the present embodiment, the alkali barrier layer and the transparent conductive film are formed by the above-described thin film forming method. Therefore, a high performance thin film solar cell can be manufactured.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these. In the present embodiment, a description will be given of a film forming experiment of a transparent conductive film for a thin film solar cell as an example. Note that the present invention is not limited only to the conditions described below, and various thin films such as an alkali barrier layer can be formed by adjusting the heating temperature by the heating unit or by adjusting the material used for the raw material solution. It can be applied to membranes.

<Example 1>
In this example, a transparent conductive film was formed on the substrate 1 using the thin film forming apparatus 100 shown in FIG. In the thin film deposition apparatus 100 of FIG. 1, the heating unit 3 is connected to the lower part of the spraying device 6, and the mounting table 2 is installed below the heating unit 3. The substrate 1 was fixed on the mounting table 2. As the atomizer 4, three sprays are used.

When the vertical distance from the upper surface of the substrate 1 to the upper end of the heating unit 3 is La, the vertical distance Lb from the lower end of the sprayer 4 to the upper surface of the substrate 1 is 1/2 La. As the raw material solution 5, an aqueous solution containing 0.9 mol / L SnCl ₄ and 0.3 M NH ₄ F and containing 30 mass% HCl and 2.5 mass% methanol was used. The boiling point of this aqueous solution is about 70 ° C.

  And the temperature inside the said heating part 3 was 590 degreeC, and the transparent conductive film was formed into a film on the 1000x1400mm board | substrate by spraying the mist 9 for 60 second with the sprayer 4 with a water head difference of -150mm. When the film thickness of the transparent conductive film thus formed was measured with a stylus type surface shape measuring instrument (product name: DEKTAK (manufactured by ULVAC, Inc.)), the results shown in Table 1 were obtained.

  In addition, haze rate uses the numerical value shown by haze (%) = {total light transmittance (%)-parallel light transmittance (%)} / total light transmittance (%), haze meter (NDH4000; Nippon Denshoku Co., Ltd.) Moreover, the temperature of the heating part when forming a transparent conductive film was measured with a thermocouple (product name: K thermocouple (manufactured by ASONE Corporation)).

<Example 2>
In the configuration of Example 1, a transparent conductive film was formed by changing the vertical distance Lb from the upper surface of the substrate 1 to the upper end of the heating unit 3 from 1/2 La to 2/3 La. Others are the same as in the first embodiment.

<Example 3>
In the configuration of Example 1, a transparent conductive film was formed by changing the vertical distance Lb from the upper surface of the substrate 1 to the upper end of the heating unit 3 from 1/2 La to La. Others are the same as in the first embodiment.

<Comparative Example 1>
In the configuration of Example 1, a transparent conductive film was formed by changing the vertical distance Lb from the upper surface of the substrate 1 to the upper end of the heating unit 3 from 1/2 La to 1/3 La. Others are the same as in the first embodiment.

<Comparative example 2>
In the configuration of Example 1, a transparent conductive film was formed by changing the vertical distance Lb from the upper surface of the substrate 1 to the upper end of the heating unit 3 from 1/2 La to 4/3 La. Others are the same as in the first embodiment.

<Measurement results>
Table 1 shows the measurement results of Examples 1 to 3 and Comparative Examples 1 and 2.

  In Examples 1 to 3, the transparent conductive film formed on the substrate 1 resulted in a larger film thickness as the distance Lb was smaller. The film thickness when sprayed at a distance close to the substrate 1, that is, the film thickness shown in Comparative Example 1 was the largest, but the resistance value was large and the film unevenness was very large. In the result of Comparative Example 2, the film thickness was thin and there was a problem in tact time. Examples 1 to 3 were generally good results.

(Additional notes)
Although the embodiments and examples of the present invention have been described as described above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  In other words, the present invention is not limited to the above-described embodiment, and various modifications are possible within the scope shown in the claims, and can be obtained by combining technical means appropriately modified within the scope shown in the claims. Embodiments are also included in the technical scope of the present invention.

  The present invention can also be expressed as follows.

  The thin film deposition apparatus of the present invention is a thin film deposition apparatus for depositing a thin film by spraying from a sprayer for spraying the mist onto a substrate by changing the raw material solution into mist, A cooling unit for cooling the raw material solution; and a heating unit for heating the mist. The heating unit is maintained at a temperature of 500 to 600 ° C. and below the inside. When the substrate is installed or the substrate is moved by a moving mechanism, and the vertical distance from the upper surface of the substrate to the upper end of the heating unit is L, the lower surface of the sprayer and the upper surface of the substrate The vertical distance is up to 1/2 L to L.

  In the thin film deposition apparatus of the present invention, it is preferable that the cooling means cools the raw material solution in the sprayer to a boiling point or lower of the raw material solution.

  In the thin film deposition apparatus of the present invention, the cooling means is a pipe provided around the sprayer, and the raw material solution in the sprayer is preferably water-cooled by the pipe.

  The thin film forming method of the present invention is a thin film forming method for forming a thin film on a substrate, the step of cooling the raw material solution in the sprayer by air cooling or water cooling, and the raw material solution by the sprayer To the mist, spraying the mist onto the substrate, and heating the mist with a heating unit maintained at 500 to 600 ° C., from the upper surface of the substrate to the upper end of the heating unit When the distance in the vertical direction is L, the distance in the vertical direction from the lower end of the sprayer to the upper surface of the substrate is ½ L to L.

  In the thin film deposition method of the present invention, the step of spraying the mist onto the substrate may be performed while moving the substrate in a direction substantially perpendicular to a direction in which the mist is sprayed.

  The present invention is particularly suitable for forming a thin film on a glass substrate used in a thin film solar cell.

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Loading stand 3 Heating part 4 Nebulizer 5 Raw material solution 6 Spraying apparatus 7 Gas introduction port 8 Nozzle 9 Mist 10 Exhaust port 17 Heating part 18 Cooling part 100 Thin film deposition apparatus 200 Film formation line

Claims (13)

Having a sprayer that changes the raw material solution into mist and sprays the mist onto the substrate from the spray port;
A thin film forming apparatus for forming a thin film on the substrate by spraying from the sprayer,
Cooling means for cooling the raw material solution in the sprayer;
A heating unit for heating the mist,
The substrate is provided in the lower part of the heating unit so as to face the spray port,
When the vertical distance from the upper surface of the substrate to the upper end of the heating unit is La, the vertical distance Lb from the spray port to the upper surface of the substrate is 1/2 La to La. Thin film deposition equipment.   The thin film deposition apparatus according to claim 1, wherein the distance Lb is 2/3 La to 5/6 La. The thin film is a transparent conductive film;
3. The thin film deposition apparatus according to claim 1, wherein a temperature inside the heating unit is 500 to 600 ° C. 4.   The thin film deposition apparatus according to claim 3, wherein a temperature inside the heating unit is 530 to 570 ° C. 5.   The thin film deposition apparatus according to claim 1, wherein the substrate is movable by a moving mechanism.   The thin film deposition apparatus according to claim 1, wherein the cooling unit cools the raw material solution in the sprayer to a boiling point or less of the raw material solution. The cooling means is a pipe provided around the sprayer,
The thin film deposition apparatus according to claim 1, wherein the raw material solution in the sprayer is water-cooled by the pipe. A thin film deposition method for depositing a thin film on a substrate,
A cooling step for cooling the raw material solution in the atomizer;
The spraying step of changing the raw material solution into mist by the sprayer, and spraying the mist from the spray port of the sprayer to the substrate;
A heating step of heating the mist by a heating unit,
The substrate is provided in the lower part of the heating unit so as to face the spray port,
When the vertical distance from the upper surface of the substrate to the upper end of the heating unit is La, the vertical distance Lb from the spray port to the upper surface of the substrate is 1/2 La to La. Thin film deposition method. The thin film is a transparent conductive film;
The method for forming a thin film according to claim 8, wherein the temperature inside the heating unit is 500 to 600 ° C.   10. The thin film deposition method according to claim 8, wherein in the spraying step, the substrate is moved in a direction substantially perpendicular to a direction in which the mist is sprayed.   The thin film deposition method according to claim 8, wherein, in the cooling step, the raw material solution in the sprayer is cooled to a boiling point or less of the raw material solution. A thin-film solar cell manufacturing method including a first film forming step of forming a thin film of an alkali barrier layer on a glass substrate,
The method of manufacturing a thin film solar cell, wherein the first film forming step includes each step of the thin film forming method according to any one of claims 8 to 11. A first film forming step of forming a thin film of an alkali barrier layer on a glass substrate;
A method of manufacturing a thin film solar cell, comprising: a second film forming step of forming a thin film of a transparent conductive film on the alkali barrier layer,
The thin film solar, wherein at least one of the first film forming step and the second film forming step includes each step of the thin film forming method according to claim 8. Battery manufacturing method.

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