JP5015331B2 - Thin film manufacturing method and thin film manufacturing apparatus - Google Patents

Description

  The present invention relates to a thin film manufacturing method and a thin film manufacturing apparatus.

  As a method for producing a thin film on the surface of a substrate to be treated, a chemical vapor deposition method is widely known. Examples of the vapor phase growth method include a method performed in a vacuum system such as a thermal CVD method and a plasma CVD method, and a droplet spray method performed in a non-vacuum system such as a mist CVD method and a spray CVD method. . The droplet spraying method has attracted attention in recent years because the apparatus configuration is simple and the process is simple as compared with the thermal CVD method and the plasma CVD method.

  Specifically, in the droplet spraying method, a liquid material containing a thin film raw material is formed into droplets having a particle diameter of about several μm to several tens of μm, and sprayed onto the surface of the substrate to be processed. In this method, the thin film material attached to the surface of the film is grown by crystal growth. That is, in the droplet spraying method, a thin film is formed by chemically reacting the raw material of the thin film sprayed on the surface of the substrate to be processed using the thermal energy of the substrate to be processed. For this reason, in order to form a desired thin film using the droplet spraying method, temperature control of the surface of the substrate to be processed is important. In particular, when forming a transparent conductive film which is one of the thin films, stricter temperature control is required. The reason is as follows.

  The transparent conductive film can be used as, for example, an electrode on the light-receiving surface side of a thin film solar cell. In order to be suitable as the electrode, in addition to transparency, conductivity (low resistance), surface shape It is important to satisfy the characteristics such as. Specifically, the electrical conductivity of the transparent conductive film tends to require an electrical conductivity of about 20 Ω / □ or less in terms of sheet resistance. In response to this demand, by adding a dopant to the transparent conductive film to increase the carrier concentration of the transparent conductive film, or by increasing the carrier mobility by increasing the crystallinity of the metal oxide constituting the transparent conductive film The necessary electrical conductivity is imparted.

  Further, as a surface shape suitable for the transparent conductive film, there is a texture structure such as an uneven structure. Since the surface of the transparent conductive film has a texture structure, the light that has passed through the transparent conductive film can be scattered by the texture structure. Therefore, the light that has passed through the transparent conductive film is efficiently contained in the film that has a photoelectric conversion effect. Can be trapped in. Such a degree of scattering of transmitted light can be expressed by a haze ratio, but the electrode on the light receiving side generally tends to require a haze ratio of about 5% or more. The haze rate is a percentage of a value obtained by dividing the diffuse transmittance when a light beam is incident on the measurement object by the total transmittance.

  However, in the droplet spraying method, for example, when a transparent conductive film is formed with the substrate to be processed at a high temperature, the crystal growth is promoted and the unevenness of the surface of the transparent conductive film is promoted. Volatilization reduces the efficiency of incorporation of the dopant into the transparent conductive film, resulting in a decrease in electrical conductivity. On the other hand, in order to prevent a decrease in electrical conductivity, when a transparent conductive film is formed with the substrate to be processed at a low temperature, unevenness is suppressed by slowing the crystal growth, and as a result. This leads to a decrease in surface shape.

  Therefore, when a transparent conductive film having suitable electrical conductivity and surface shape is produced by the droplet spraying method, the allowable range of the surface temperature of the substrate is narrow. For this reason, not only the temperature control of the substrate when manufacturing a thin film by the droplet spraying method is important, but also a strict temperature control is required when manufacturing a transparent conductive film.

Japanese Patent Laid-Open No. 2-199803 Japanese Patent Laid-Open No. 3-90579

  However, in the droplet spraying method, since the liquid material is sprayed onto the substrate to be processed in a state where gas is mixed, the thermal energy of the substrate to be processed is reduced due to the collision of the gas with the substrate to be processed. Tend to occur. In addition, the solvent contained in the liquid material evaporates on the surface of the substrate to be processed, and the thermal energy of the substrate to be processed tends to decrease. For this reason, in the droplet spraying method, the surface temperature of the substrate to be processed tends to decrease as the film forming process proceeds, and it is difficult to keep the surface temperature of the substrate to be processed constant.

  As a conventional technique, there is a technique of improving film quality by suppressing temperature drop of a substrate to be processed by intermittently performing droplet spraying on the entire surface of the substrate to be processed instead of continuously. However (for example, Patent Document 1), in the method of intermittently spraying the droplets themselves, there is a problem that a good quality film cannot be obtained because the particle size of the droplets varies every time spraying is started. Furthermore, there is a problem that the tact time is extended and the productivity of the thin film is lowered as compared with the case where spraying is continuously performed.

  Further, as a conventional technique, a shutter or the like is disposed between the droplet to be sprayed and the substrate to be processed, and liquid droplets are applied to the surface of the substrate to be processed by opening and closing the shutter or the like while spraying the droplet itself. Although there is a technique for suppressing the temperature drop of the substrate to be processed by intermittently attaching the droplets, the use efficiency of the droplets is low and the apparatus configuration is complicated.

  In addition, in the droplet spraying method, when the substrate to be processed has a certain length such as a substrate, the substrate to be processed is sent out in a certain direction to the area where the liquid material is sprayed. A feeding method is used in which a thin film is formed in order from one end side to the other end side of the surface of the substrate (for example, Patent Document 2).

  However, in the above delivery method, in order to produce a thin film having a desired thickness, it is necessary to deliver the substrate to be processed into a region where the liquid material is sprayed at a relatively low speed. In this case, droplets are sprayed on the surface of the substrate to be processed in a continuous long time, and as a result, the temperature of the surface of the substrate to be processed is lowered. For this reason, the conventional delivery method has a problem that it becomes impossible to manufacture a thin film having desired characteristics due to a decrease in the temperature of the surface of the substrate to be processed.

  Accordingly, an object of the present invention is to provide a thin film manufacturing method and a thin film manufacturing apparatus capable of suppressing a temperature decrease of a substrate to be processed without decreasing productivity in a droplet spraying method. To do.

  A first aspect of the present invention includes a step of heating a substrate to be processed and a step of spraying a liquid material toward the surface of the substrate to be processed. This is a thin film manufacturing method in which a thin film is formed by reciprocating relatively in the surface direction and changing the position where the liquid material is sprayed on the surface of the substrate to be processed.

  In the method for producing the thin film, it is preferable that the reciprocation is continuously performed once or more in the spraying step.

  In the thin film manufacturing method, the temperature difference between the maximum temperature and the minimum temperature of the surface of the substrate to be processed in the spraying step is preferably 70 ° C. or less.

  In the thin film manufacturing method, the substrate to be processed is preferably reciprocated in the spraying step.

  In the thin film manufacturing method, it is preferable to form a thin film having a texture structure on the surface as the thin film.

In the thin film manufacturing method, it is preferable to form a transparent conductive film as the thin film.
In the thin film manufacturing method, it is preferable to form a barrier layer as the thin film.

  A second aspect of the present invention is a thin film manufacturing apparatus for spraying a liquid material onto the surface of a substrate to be processed while reciprocating the heated substrate to be processed to form a thin film on the surface of the substrate to be processed. A processing unit, a holding unit installed in the processing chamber for holding the substrate to be processed, a heating unit installed in the processing chamber for heating the substrate to be processed, and a holding unit in the processing chamber A spray unit for spraying a liquid material on the surface of the substrate to be treated; a moving unit for reciprocating the holding unit relative to the spray unit in the surface direction of the substrate to be treated; And a control unit for controlling the reciprocating speed of the holding unit.

  In the thin film manufacturing apparatus, the control unit preferably controls the speed of the reciprocating movement so that the reciprocating movement is continuously performed once or more in order to form the thin film.

  In the thin film manufacturing apparatus, the control unit may control the reciprocating speed so that the temperature difference of the surface of the substrate to be processed is 70 ° C. or less when the liquid material is sprayed onto the surface of the substrate to be processed. preferable.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a thin film and the thin film manufacturing apparatus which can suppress the temperature fall of a base | substrate can be provided, without reducing productivity in the droplet spraying method.

It is typical sectional drawing of the thin film manufacturing apparatus of this Embodiment. Each of (A)-(C) is a figure which shows the relationship between the spray area | region of a liquid material, and the position of a base | substrate. It is a figure which shows the positional relationship of the base | substrate and spray area | region at the time of reciprocation in Example 1,2. 3 is a graph showing the results of Examples 1 and 2 and Comparative Example 1.

  Hereinafter, embodiments of a thin film manufacturing method and a thin film manufacturing apparatus according to the present invention will be described with reference to the drawings. The following embodiments are merely examples, and various embodiments can be implemented within the scope of the present invention. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

<Thin film manufacturing equipment>
FIG. 1 shows a schematic cross-sectional view of the thin film manufacturing apparatus of the present embodiment. The thin film manufacturing apparatus 100 in FIG. 1 sprays a liquid material on the surface of the substrate W while reciprocating the substrate W that is a heated substrate to be processed, and forms a thin film on the surface of the substrate W. It is.

First, the configuration of the thin film manufacturing apparatus 100 will be described with reference to FIG.
In FIG. 1, a thin film manufacturing apparatus 100 includes a processing chamber 1, in which a holding unit 2 for holding a substrate W, a heating unit 3 for heating the substrate W, and a substrate W are provided. A spray unit 4 for spraying the liquid material, a moving unit 5 for reciprocating the holding unit 2, and a control unit 6 for controlling the reciprocating speed are arranged.

  The processing chamber 1 only needs to be able to protect the substrate W loaded therein from external factors such as dust, and does not need to have high sealing properties unlike the processing chamber used in the thermal CVD method. Further, the processing chamber 1 may be provided with a piping line, a valve, and the like connected to the gas supply unit so that the gas in the inside thereof can be replaced.

  The holding unit 2 can hold the substrate W placed on the placement surface 2a. The configuration of the holding unit 2 is not particularly limited. For example, the holding unit 2 can be configured to adsorb the substrate W on the placement surface 2a from the back side of the substrate W. In the present embodiment, a thin film is formed on the surface of the substrate W exposed upward in the drawing.

  The heating unit 3 should just be arrange | positioned in the position which can heat the board | substrate W. FIG. For example, as shown in FIG. 1, the heating efficiency of the footprint and the substrate W can be improved by being incorporated in the holding unit 2. As the heating unit 3, for example, a hot plate, a hot wire, or the like can be used.

  The spray unit 4 is disposed above the holding unit 2 and can spray the liquid material downward in the figure. Although the structure of the spray unit 4 is not specifically limited, For example, as shown in FIG. 1, the two-fluid spray type nozzle 7 can be used suitably. Although three nozzles 7 are shown in FIG. 1, the number is not particularly limited, and can be changed as appropriate according to, for example, the spray amount necessary for film formation, the spray region, and the like.

  Piping lines 1L and 2L are respectively connected to the nozzle 7. The piping line 1L is a piping line for supplying the gas discharged from the gas supply unit 8 to the nozzle 7, and the piping line 2L is a liquid. This is a pipe for supplying the liquid material supplied from the supply unit 9 to the nozzle 7. The nozzle 7 can spray the liquid material in the form of particulate droplets having a small particle diameter by ejecting from the ejection port in a state where the gas and the liquid material are mixed. In addition, in FIG. 1, the spray area | region where a droplet is sprayed is shown with a dotted line. When the substrate W is located in the spray region surrounded by the dotted line, the droplets adhere to the surface of the substrate W.

  The moving unit 5 only needs to be configured to reciprocate the holding unit 2 in the direction of the surface of the substrate W indicated by an arrow in the drawing. For example, as shown in FIG. 1, the moving unit 5 may be provided below the holding unit 2. . Moreover, the drive shaft 10 fixed in the process chamber 1 may be slidably inserted so that the movement direction of the movement unit 5 may not shake with respect to the surface direction.

  The reciprocating direction of the moving unit 5 is the surface direction of the substrate W. For example, when the shape of the substrate W is a belt shape, it is preferably the longitudinal direction of the surface direction of the substrate W. Moreover, when it is a substantially square, it is preferable that it is the direction of at least any one side. Furthermore, the reciprocating direction is preferably perpendicular to the spraying direction (the direction from the top to the bottom in FIG. 1).

  The control unit 6 controls the speed of the reciprocating movement of the moving unit 5. Specifically, the control unit 6 can control the stroke of the reciprocating movement, the moving speed, the number of reciprocations, and the like. The ejection unit 4 may be controlled by the control unit 6. Although the control of the ejection unit 4 may be performed by another control unit (not shown), the footprint of the processing chamber 1 is improved by controlling the ejection unit 4 and the moving unit 5 by the control unit 6.

Next, the film forming operation of the thin film manufacturing apparatus 100 will be described with reference to FIG.
In the thin film manufacturing apparatus 100, the holding unit 2 holds the substrate W carried into the processing chamber 1 on the placement surface 2 a of the holding unit 2. Then, the heating unit 3 heats the substrate W held by the holding unit 2 so that the surface temperature of the substrate W becomes a predetermined temperature. The surface temperature of the substrate W can be detected, for example, by providing a detector such as a thermocouple in the holding unit 2 so as to contact the substrate W directly or indirectly.

  On the other hand, the spray unit 4 ejects the liquid material as particulate droplets from a nozzle 7 in a predetermined ejection direction, for example, downward in the figure. Specifically, when the gas is supplied from the gas supply unit 8 to the nozzle 7 through the piping line 1L, the liquid material stored in the liquid supply unit 9 is sucked into the piping line 2L. And in the nozzle 7, gas and a liquid material are mixed, and a particulate liquid material is sprayed with gas from the jet nozzle of the nozzle 7. FIG. The sprayed liquid material is diffused downward in the figure of the nozzle 7.

  On the other hand, the control unit 6 moves the moving unit 5 from the position shown in FIG. 1 to the right in the drawing, and then moves it again to the position shown in FIG. This reciprocal movement will be described with reference to FIGS.

  Each of FIGS. 2A to 2C is a diagram showing a positional relationship between the spray region of the liquid material and the substrate W, and shows a state in which the inside of the processing chamber 1 is viewed from above. A region surrounded by a dotted line in the figure is a spray region of the liquid material, and indicates a region where droplets can adhere to the surface of the substrate W when the surface of the substrate W enters the spray region. Accordingly, the ejection unit 4 is positioned above the space surrounded by the dotted line. In the figure, L indicates a reciprocating stroke.

  In the film forming operation of the thin film manufacturing apparatus 100, when the moving unit 5 is located at the position shown in FIG. 1 as shown in FIG. 2A, the substrate W held by the holding unit 3 on the moving unit 5 and Since it does not overlap with the spray region, the substrate W is not exposed to the liquid material. When the moving unit 5 moves to the right side in FIG. 1 under the control of the control unit 6, as shown in FIG. 2B, the holding unit 2 and the substrate W held by the holding unit 2 are also on the right side in FIG. Will be moved to. By this movement, the substrate W is caused to enter the spray region, so that the surface of the substrate W is exposed to the liquid material. Then, the control unit 6 continues to move the moving unit 5 to the right side in the figure and moves it to the position shown in FIG. Through the above-described outward path, the substrate W enters the spray region and passes through the spray region, whereby the liquid material adheres to the entire surface of the substrate W. Subsequently, the moving unit 5 moves from the position shown in FIG. 2C to the position shown in FIG. 2A under the control of the control unit 6. By this outward path, the substrate W enters the spray area from the opposite side to the forward path and passes through the spray area.

  That is, by the control of the control unit 6, the moving unit 5 moves in order to the positions of FIGS. 2 (A), 2 (C), and 2 (A), and by the reciprocating movement of the holding unit 2 associated therewith, The substrate W can pass through the spray region twice. In the above operation, the control unit 6 is configured so that the amount of spray of the liquid material, the moving speed of the moving unit 5, and the like so that the film forming process is completed while the reciprocating movement is continuously performed at least once. The stroke of the reciprocating movement of the moving unit 5 is controlled.

  According to the operation of the thin film manufacturing apparatus 100 described above, the liquid material can be sprayed from the spray unit 4 while the substrate W is heated by the heating unit 3. Further, the liquid material can be deposited discontinuously on the entire surface of the substrate W by the reciprocating movement of the moving unit 5 by the control unit 6. When the liquid material adheres to the surface of the substrate W that has entered the spray region, the substrate W is continuously heated by the heating unit 3 while being moved by the moving unit 5. When the solvent in the solvent evaporates and the solute crystallizes, a thin film using the solute as a raw material can be produced.

  Here, in order to facilitate understanding of the effect of the present invention, the film forming process A by the thin film manufacturing apparatus 100 is compared with the film forming process B by the conventional delivery method. In the film forming process A and the film forming process B, it is assumed that the liquid material spray amount (ml / second), the liquid material spray region, and the surface size of the substrate W are the same, and the substrate W in the film forming process A is reciprocated. It is assumed that the speed is twice the sending speed of the substrate W in the film forming process B. That is, in the film forming process A, the film formation of the thin film is completed by passing the substrate W twice through the spray region, and in the film forming process B, the substrate W is passed through the spray region 1 / the speed of the film forming process A. The film formation is completed by passing the film once at a double speed.

In the above assumption, regarding an arbitrary point (W ₁ ) on the substrate surface, in the film forming process B, a predetermined amount of the liquid material necessary for forming the thin film is sprayed for a continuous time, for example, 2 T seconds. On the other hand, according to the film forming process A, half of the total amount is intermittently sprayed for T seconds in each of the outward path and the return path. Further, in the film forming process A, W ₁ moves a reciprocating stroke L between the timing when the liquid material is sprayed on W ₁ in the forward path and immediately before the liquid material is sprayed on W ₁ on the return path. There is time to do. For this reason, the temperature of W ₁ is decreased by spraying the liquid material in the forward path, but the temperature of W ₁ is increased during the time required to move the stroke L, so that the surface temperature is recovered in the return path. In this state, the liquid material is sprayed.

That is, according to the present embodiment, during the film formation process, the holding unit 2 is reciprocated at least once (n times) to perform the film formation process, thereby continuously with respect to an arbitrary point W _{1 on the} substrate W. The amount of liquid material sprayed can be (1 / 2n) times that of the conventional delivery method, and the time during which the surface of W ₁ is not exposed to the liquid material during reciprocation In the meantime, the surface temperature of W ₁ can be raised. Therefore, according to the present embodiment, it is possible to suppress the temperature drop of the substrate surface caused by the spraying of the liquid material in the forward path and the backward path with respect to the conventional delivery method, and further, during the reciprocation, the substrate surface The temperature can be increased.

  For this reason, according to the present embodiment, the temperature difference between the maximum temperature and the minimum temperature of the surface of the substrate W during the film forming process can be reduced, so that the droplet spraying method also has desired characteristics. A thin film can be manufactured easily. In addition, when the film forming process is completed by n reciprocating movements, the tact time required for the film forming process is set to be equal to that of the conventional sending method by making the reciprocating movement speed 2n times the conventional sending speed. Since it can be the same, productivity is not reduced. Further, since the amount of the liquid material adhering to the surface of the substrate W when passing through the spray region once is reduced, the degree of decrease in the temperature of the substrate due to passing through the spray region once becomes small.

  According to the thin film manufacturing apparatus 100 of the present embodiment, as described above, the temperature difference between the maximum temperature and the minimum temperature of the surface of the substrate W can be reduced to suppress a decrease in the temperature of the substrate W. Film formation under suitable temperature conditions corresponding to the characteristics of the thin film becomes possible. For this reason, for example, a transparent conductive film having a narrow temperature range allowed in the film forming process can be easily manufactured.

  Further, according to the thin film manufacturing apparatus 100 as described above, the temperature difference on the surface of the substrate W when the liquid material is sprayed onto the surface of the substrate W is adjusted by adjusting the number of reciprocating movements required for the film forming process. The temperature can be set at or below 40.degree.

  Moreover, in the thin film manufacturing apparatus 100, it is preferable that the ejection direction of the liquid material and the reciprocating direction of the holding unit 2 are perpendicular to each other. In this case, droplets of the liquid material can be uniformly attached to the surface of the substrate W.

  In addition, as shown in FIGS. 2A to 2C, the stroke of the reciprocating movement is a stroke that can take a state where the entire surface of the substrate W is located outside the spray area in both the left and right sides of the spray area. Preferably there is.

  In the above-described embodiment, the case where the reciprocation is performed once has been described. However, the control unit 6 controls the reciprocation speed so that the number of reciprocations necessary for the thin film forming process is two times or more. Thus, it goes without saying that the temperature difference on the surface of the substrate W during the film forming process is further reduced.

<Method for producing thin film>
Next, the manufacturing method of the thin film which concerns on this Embodiment is demonstrated. Here, the manufacturing method of the transparent conductive film utilized for the electrode of the light-receiving side of a thin film solar cell is demonstrated.

  First, in the step of heating the substrate to be processed, the substrate W is heated. The transparent conductive film is composed of a crystal of a metal oxide such as tin, zinc, indium, cadmium, strontium, or titanium. In this case, the temperature of the substrate W during the film formation process is at least 450 ° C. or higher. Is preferred. For this reason, in this step, the substrate W is preferably heated so that the surface temperature becomes 470 ° C. or higher. Furthermore, in consideration of a decrease in the surface temperature due to the spraying of the liquid material, it is preferable that the surface temperature is heated to 500 ° C. or higher.

  On the other hand, in the step of spraying the liquid material toward the surface of the substrate to be processed, the liquid material is sprayed in the form of particulate droplets toward the surface of the substrate W. The liquid material contains a raw material for the transparent conductive film and a solvent. Moreover, the liquid material may contain a dopant that is doped into the transparent conductive film. As a raw material for the transparent conductive film, it is common to use a metal chloride of a metal constituting the transparent conductive film that is a metal oxide. In addition, it is preferable that the density | concentration of the metal chloride in a liquid material shall be 0.1 mol / L or more and 3 mol / L or less on the property.

  Specifically, for example, when producing a transparent conductive film made of antimony-doped tin oxide, a solution obtained by dissolving stannic chloride and antimony trichloride in a solvent such as water can be used as the liquid material. For example, when manufacturing a transparent conductive film made of tin-doped indium oxide, a solution in which tin tetrachloride and indium trichloride are dissolved in a solvent such as water can be used as the liquid material. In addition, by spraying the liquid material with a gas whose volume has been expanded, spraying can be performed in a state where the particle diameters of the droplets are made more uniform. For example, air can be used as the gas.

  Through the above steps, the temperature of the substrate W reaches a predetermined temperature, and the liquid material is ejected toward the substrate W. Note that the front-rear relationship between the timing of starting the heating step and the timing of starting the ejecting step is not particularly limited, and at least the surface of the substrate W is heated when droplets adhere to the substrate W. Just do it.

  In the spraying step, the position of the liquid material sprayed on the surface of the substrate W is changed by reciprocating the substrate W relatively in the surface direction of the substrate W. Specifically, when the substrate W reciprocates along the surface direction of the substrate W, a liquid material spraying area is present in the middle of the reciprocating path so that the liquid material with respect to the surface of the substrate W can be obtained. The sprayed position can be varied. Thereby, a transparent conductive film can be formed on the surface of the substrate W.

  The reciprocation will be described with reference to FIGS. 2A to 2C. In the spraying step, the substrate W (see FIG. 2A) positioned outside the spray region of the liquid material is the substrate W. Moves to the right side in the drawing (the longitudinal direction of the substrate W in FIG. 2) and passes through the spray region (see FIGS. 2B and 2C). Subsequently, the substrate W changes its direction of movement, moves to the left side in the figure, which is the surface direction of the substrate W, and moves to the position shown in FIG. 2A while passing through the spray region again.

  The substrate W is moved from the position of FIG. 2A to FIG. 2C, and is again moved to the position of FIG. 2A, whereby the substrate W and the position of the substrate W of FIG. The spray region between the position of the substrate W in (C) can pass once each in the forward path and the return path. When the substrate W passes through the spray region, the liquid material adheres to the surface of the substrate W. At this time, since the substrate W is continuously heated, the liquid material in the liquid material attached to the surface of the substrate W As the solvent evaporates and the solute crystallizes, a transparent conductive film is formed on the surface of the substrate W.

  According to the thin film manufacturing method of the present embodiment described above, the substrate W can pass through the spray region at least twice by moving the substrate W back and forth in the film forming process. Although the liquid material adheres to the surface of the substrate W when passing through the spray region, as described above, the amount of the liquid material sprayed continuously can be reduced as compared with the conventional delivery method. The temperature drop of the substrate surface caused by the spraying of the liquid material can be suppressed, and the temperature of the substrate surface can be raised during the reciprocating movement.

  For this reason, according to the present embodiment, the temperature difference between the maximum temperature and the minimum temperature of the surface of the substrate W during the film forming process can be reduced, so that the droplet spraying method also has desired characteristics. A thin film can be manufactured easily. In addition, when the film forming process is completed by n reciprocating movements, the tact time required for the film forming process is set to be equal to that of the conventional sending method by making the reciprocating movement speed 2n times the conventional sending speed. Since it can be the same, productivity is not reduced. It should be noted that the film formation time required to form a film having a predetermined thickness on the substrate W having a predetermined size can be determined from the amount of the liquid material sprayed per unit time.

  According to the present embodiment, as described above, the temperature difference between the maximum temperature and the minimum temperature on the surface of the substrate W can be reduced to suppress a decrease in the temperature of the substrate W. It is possible to form a film under the suitable temperature conditions. For this reason, for example, a film having a texture structure with a narrow temperature range allowed in the film forming process, for example, a transparent conductive film can be easily manufactured.

  Further, according to the present embodiment, the number of reciprocating movements of the substrate W during the spraying process is preferably one or more, and the surface of the substrate W during the spraying process is adjusted by adjusting the number of reciprocating movements. The temperature difference between the maximum temperature and the minimum temperature can be set to 70 ° C. or lower, and further can be set to 40 ° C. or lower. For this reason, according to the manufacturing method of the thin film of this Embodiment, a transparent conductive film can be manufactured more suitably.

  In addition, when using soda lime glass containing an alkali metal as the substrate W in the thin film solar cell, the substrate W and the transparent conductive film are suppressed in order to prevent the alkali component of the substrate W from diffusing into the transparent conductive film. It is preferable to provide a barrier layer between them. Since the barrier layer is a layer made of a crystal such as aluminum oxide or zinc oxide, it can be suitably manufactured by the method for manufacturing a thin film according to the above-described embodiment, similarly to the transparent conductive film. In this case, the barrier layer and the transparent conductive film can be continuously produced by switching the composition of the liquid material to be sprayed. In particular, since the barrier layer is manufactured by the thin film manufacturing method of the present embodiment, the decrease in the substrate surface temperature due to the spraying of the material can be reduced in the barrier layer film forming step, so that the temperature condition with little variation is achieved. Therefore, a barrier layer having a uniform film thickness and uniform barrier characteristics can be formed.

  Although the case where the substrate W is reciprocated with respect to the fixed spray region has been described in the present embodiment, the spray region may be reciprocated with respect to the fixed substrate W. In this case, the ejection direction of the liquid material (the direction from the upper side of the paper in FIG. 2 toward the back side of the paper) is constant, and the position of the spray region moves. However, it is more preferable to reciprocate the substrate W in consideration of the case where the dispersion of the droplets becomes non-uniform by moving the spray region.

  In the present invention described in detail above, the larger the size of the substrate W, the greater the effect of suppressing the temperature drop of the surface of the substrate W. This is because when a large-sized substrate W is reciprocated, the reciprocating stroke and the time required for reciprocating movement become long. Therefore, when an arbitrary point on the substrate W is viewed, the time during which the liquid material is not sprayed becomes long. In particular, it is possible to secure a sufficient time for the surface temperature of the substrate W, which has been lowered by spraying the liquid material, to recover. This can be said to be suitable for the recent trend of increasing the size of devices manufactured by stacking thin films represented by thin film solar cells.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Example 1>
In this example, the above-described manufacturing method was performed using the thin film manufacturing apparatus 100 to manufacture a transparent conductive film on the surface of the glass substrate. Below, the specific manufacturing method of a transparent conductive film is demonstrated.

  First, prior to the film formation process, a substrate W and a liquid material were prepared. As the substrate W, a glass substrate having a length × width of 100 mm × 100 mm was prepared. In order to form fluorine-doped tin oxide as a transparent conductive film, liquid materials containing stannic chloride and ammonium fluoride at 0.9 mol / L and 0.1 mol / L, respectively, were prepared. The liquid material solvent was a mixed solution of water, hydrochloric acid, and methanol. Then, the prepared glass substrate was carried into the processing chamber 1, held in the holding unit 2, and the prepared aqueous solution was accommodated in the liquid supply unit 9. The gas supply unit 8 accommodated compressed air.

  Next, the glass substrate was heated by the heating unit 3 comprising a hot plate. At this time, when the glass substrate was heated at a set temperature of the hot plate of 540 ° C., the surface temperature of the glass substrate rose to about 500 ° C. In addition, the temperature of the surface of a glass substrate was measured with the thermocouple affixed on the edge of the surface of the glass substrate.

  On the other hand, in the spray unit 4, the liquid material was ejected in the form of particles together with the gas from the nozzle 7 downward in the figure. About the spray area | region where a liquid material is sprayed, the width | variety with respect to the reciprocation direction of a glass substrate was 80 mm. In addition, the width | variety orthogonal to the reciprocating direction of the glass substrate of a spray area | region exceeded 100 mm. In the present embodiment, the ejection direction of the liquid material from the nozzle 7 and the reciprocating direction of the glass substrate are substantially orthogonal to each other.

  Then, the control unit 6 controlled the reciprocating speed of the moving unit 5 to 15 mm / second and the reciprocating stroke to 180 mm, and the holding unit 2 was reciprocated for 180 seconds. Therefore, in this film forming process, the glass substrate has reciprocated 7.5 times.

  The positional relationship between the glass substrate and the spray area in this reciprocal movement will be described with reference to FIG. 3. The glass substrate moves from the position on the left side in the figure toward the right side in the forward path, and the entire surface of the glass substrate moves through the spray area. Immediately after passing, the moving direction is switched to the opposite direction, and subsequently, the entire surface of the surface passes through the spray region in the return path.

  During the 180 seconds during which the glass substrate reciprocates, the spray unit 4 continuously sprays the droplet material, and the heating unit 3 continues to heat the glass substrate at a constant temperature (540 ° C.). Further, the temperature of the surface of the glass substrate during the film forming process was continuously measured by the thermocouple.

  After the film formation process was completed, the glass substrate after the film formation process was taken out of the processing chamber 1 and the haze ratio and sheet resistance were measured. The haze ratio was measured using a commercially available haze meter (C light source), and the sheet resistance was measured using a 4-probe method (JIS K7194). The results are shown in Table 1.

<Example 2>
A transparent conductive film made of fluorine-doped tin oxide was formed by the same method as in Example 1 except that the reciprocating speed of the moving unit 5 was set to 150 mm / second. Therefore, in this film forming process, the glass substrate has reciprocated 75 times.

  After the film formation process was completed, the glass substrate after the film formation process was taken out of the processing chamber 1, and the haze ratio and sheet resistance were measured by the same method as described above. The results are shown in Table 1.

<Comparative Example 1>
A transparent conductive film made of fluorine-doped tin oxide was formed by a conventional delivery method. Specifically, in the thin film manufacturing apparatus 100, after changing the moving unit 5 so as to move only in the right direction in FIG. 1, the moving speed of the moving unit 5 was controlled to 1 mm / second by the control unit 6. Therefore, in this film forming process, the glass substrate is only moved once from the left position shown in FIG. 3 to the right position. Other than that, a transparent conductive film was formed in the same manner as in Example 1.

  After the film formation process was completed, the glass substrate after the film formation process was taken out of the processing chamber 1, and the haze ratio and sheet resistance were measured by the same method as described above. The results are shown in Table 1.

  FIG. 4 shows changes with time in the temperature of the surface of the substrate measured in each film forming process. In FIG. 4, the dotted line shows the change over time during the film forming process of the surface temperature of the glass substrate in Example 1, and the practice shows the change over time of the surface temperature of the glass substrate in Example 2 during the film forming process. These show the time-dependent change during the film-forming process of the surface temperature of the glass substrate in the comparative example 1. FIG. Regarding the elapsed time (seconds) on the horizontal axis, the 120th of the elapsed time corresponds to the time when the reciprocal movement or delivery of the glass substrate is started, and the elapsed time of 300 seconds is the time when the reciprocal movement or delivery is completed. Applicable.

  Referring to Table 1, in Example 1, the transparent conductive film had a haze ratio of 5% and a sheet resistance of 9Ω / □. Therefore, in Example 1, the transparent conductive film provided with the haze rate (5% or more) calculated | required as an electrode of the light reception side of a thin film solar cell and sheet resistance (20 ohms / square or less) was able to be manufactured. On the other hand, in Comparative Example 1, the haze ratio of the transparent conductive film was 15%, and the sheet resistance was 150Ω / □.

  Referring to FIG. 4, in Example 1, it was found that the minimum temperature of the substrate while the liquid material was sprayed was 430 ° C. Therefore, the temperature difference between the maximum temperature and the minimum temperature of the substrate during the film forming process in Example 1 is 70 ° C. On the other hand, in Comparative Example 1, it was found that the surface temperature of the substrate decreased to about 400 ° C. while the liquid material was sprayed, and the temperature difference was 100 ° C. This is considered to be because the surface of the glass substrate is continuously exposed to the liquid material.

  Here, generally, when a transparent conductive film is formed with the substrate at a high temperature, the haze ratio tends to increase and the sheet resistance tends to decrease, and the transparent conductive film is formed with the substrate at a low temperature. When the film is formed, the haze ratio decreases and the sheet resistance tends to increase. However, comparing Example 1 with Comparative Example 1, it can be seen from FIG. 4 that the transparent conductive film of Comparative Example 1 is formed with the substrate at a lower temperature than the transparent conductive film of Example 1. Nevertheless, the result is a very high sheet resistance. The reason for this is not clear, but it is considered that the sheet resistance increases because the crystal growth is not sufficient when the temperature of the glass substrate is about 400 ° C. or lower.

  As described above, by comparing Example 1 and Comparative Example 1, when the temperature difference between the maximum temperature and the minimum temperature of the surface of the substrate during the film forming process is 70 ° C. (Example 1), the thin film It turned out that a transparent conductive film suitable as an electrode of a solar cell can be manufactured.

  Moreover, with reference to Table 1, in Example 2, the haze rate of the transparent conductive film was 13%, and the sheet resistance was 15Ω / □. Therefore, in Example 2, the transparent conductive film provided with the haze rate and sheet resistance which are calculated | required as the electrode of the light reception side of a thin film solar cell was able to be manufactured.

  Referring to FIG. 4, in Example 2, it was found that the minimum temperature of the substrate while the liquid material was sprayed was 460 ° C. Therefore, the temperature difference between the maximum temperature and the minimum temperature of the substrate during the film forming process in Example 2 is 40 ° C. In Example 2, the glass substrate was reciprocated at a movement speed faster than that in Example 1. By comparing Example 1 and Example 2, the speed of reciprocation was increased, and It was found that a transparent conductive film with higher characteristics can be produced by reducing the temperature difference between the maximum temperature and the minimum temperature of the substrate during film processing.

  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.

  The present invention can be widely used for the production of a thin film on the surface of a substrate, and can be particularly suitably used for the production of a transparent conductive film and a barrier layer.

  1 processing chamber, 2 holding unit, 3 heating unit, 4 spraying unit, 5 moving unit, 6 control unit, 7 nozzle, 8 gas supply unit, 9 liquid supply unit, 10 drive shaft, 1L, 2L piping line, 100 thin film manufacturing apparatus.

Claims (5)

Heating the substrate to be treated;
Spraying a liquid material toward the surface of the substrate to be processed,
In the spraying step,
Said forward by backward movement to the surface direction of the substrate to be processed to the substrate to be processed with respect to the spray area of the liquid material, a thin film while varying the position to be sprayed in the liquid material in the surface of the target substrate Deposit,
The reciprocating movement is performed so that the substrate to be processed passes through the spray region of the liquid material, and the first position is different from the spray region of the liquid material and the spray region of the liquid material. Reciprocating between a second position located opposite to the position,
Performing the reciprocating motion one or more times in succession,
A method for producing a thin film, wherein a temperature difference between a maximum temperature and a minimum temperature at the edge of the surface of the substrate to be processed is 70 ° C. or less during the spraying step.   The thin film manufacturing method according to claim 1, wherein a thin film having a concavo-convex structure is formed as the thin film.   The method for producing a thin film according to claim 1, wherein a transparent conductive film is formed as the thin film. As the thin film, said disposed between the transparent conductive film and the substrate to be processed, and the alkali component contained in the substrate to be processed is deposited suppressing barrier layer to diffuse before KiToru transparent conductive film The manufacturing method of the thin film of Claim 3 . A thin film manufacturing apparatus for forming a thin film on the surface of the substrate to be processed by spraying a liquid material on the surface of the substrate to be processed while reciprocating the heated substrate to be processed,
A processing chamber;
A holding unit installed in the processing chamber and holding the substrate to be processed;
A heating unit installed in the processing chamber for heating the substrate to be processed;
A spray unit installed in the processing chamber and above the holding unit, for spraying the liquid material onto the surface of the substrate to be processed;
A moving unit for reciprocally moving the holding unit relative to the spray unit in the surface direction of the substrate to be processed;
A control unit for controlling the speed of the reciprocating movement of the holding unit,
The moving unit has a first position different from the spray region of the liquid material and the liquid material so that the substrate to be processed passes through the spray region of the liquid material to which the liquid material is sprayed from the spray unit. Reciprocating between a second position located opposite to the first position with respect to the spray region of
The control unit controls the speed of the reciprocating movement so that the reciprocating movement is continuously performed one or more times in order to form the thin film;
The control unit is configured such that a temperature difference between the maximum temperature and the minimum temperature at the edge of the surface of the substrate to be processed is 70 ° C. or less during the spraying of the liquid material onto the surface of the substrate to be processed. A thin film manufacturing apparatus for controlling the reciprocating speed.

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