JP4509900B2 - Deposition equipment - Google Patents

Description

  The present invention relates to a film forming apparatus using a spray pyrolysis method.

  In the spray pyrolysis method, the raw material solution is sprayed toward a heated substrate to evaporate the solvent in the droplets adhering to the substrate surface at the beginning of the reaction, the hydrolysis reaction following the thermal decomposition of the solute, and the heat. Crystals are formed by the oxidation reaction. A technology that applies a series of reactions in which droplets adhere to the crystals (polycrystalline film) formed on the substrate as the reaction progresses, and crystal growth proceeds between the solute and lower crystals as the solvent in the droplets evaporates. It is.

FIG. 4 shows a conventional film forming apparatus using a spray pyrolysis method. The film forming apparatus 100 includes a support unit 120 on which the substrate 110 is placed and a discharge unit 130 that sprays the raw material solution in a spray form (see, for example, Patent Document 1).
However, these proposals do not describe a special exhaust device. For this reason, it is clear that control from mist spraying to diffusion and exhaust during film formation is not considered.

In the conventional apparatus, the exhaust of the mist sprayed on the substrate has not been considered. For this reason, the thickness of the film formed on the substrate becomes non-uniform.
In addition, since the film formation was performed in an open system in which no partition wall was provided as the film formation chamber, an upward air flow was generated and thermal diffusion on the substrate was likely to increase, and it was necessary to increase the heating substrate temperature. It was.

Further, since the mist freely diffuses upward, the mist adheres to members and wall surfaces constituting the device such as a nozzle, and contamination due to powder scattering on the substrate has occurred. For this reason, maintenance such as cleaning of the apparatus is required at a short cycle.
Japanese Utility Model Publication No. 06-012446

  The present invention has been devised in view of such a conventional situation, and by controlling the flow of sprayed mist, the thermal diffusion on the substrate is suppressed, and the thickness of the formed film is reduced. It is an object of the present invention to provide a film forming apparatus that can be made uniform.

A film forming apparatus according to a first aspect of the present invention is a film forming apparatus that forms a thin film on one surface of an object to be processed by spray pyrolysis, and includes a supporting means for mounting the object to be processed, and the object to be processed. At least a discharge means for spraying a mist made of the raw material solution of the thin film toward a central area of one surface of the processing body, and an exhaust means having an exhaust port provided in the vicinity of the target object, the discharge The means is configured such that the discharge port is arranged near the center of one surface of the object to be processed and in the vicinity of the upper part thereof, and the exhaust means disposes mist sprayed from the discharge port near the one surface of the object to be processed. And a hood that wraps around a space including the object to be processed and the discharge means, and the exhaust port is in the vicinity of the outer periphery of the object to be processed. Or it is arranged above and sprays the raw material solution in advance And a transport unit that includes a space for moving the mist from the adjustment chamber to the discharge unit, and the transport unit serves as a space for transporting the generated mist while guiding the mist. The temperature of the mist, the temperature of the inner wall of the transport path, and the evaporation temperature of the solvent of the raw material solution are in a relationship of mist temperature <temperature of the inner wall of the transport path <evaporation temperature of the solvent. It is characterized by that .
Film forming apparatus according to claim 2 of the present invention is characterized in that it comprises a plurality fraud and mitigating risk the exhaust port in claim 1.
According to a third aspect of the present invention, there is provided the film forming apparatus according to the second aspect , wherein the plurality of exhaust ports are provided at positions symmetrical to the object to be processed.
A film forming apparatus according to a fourth aspect of the present invention is the film deposition apparatus according to any one of the first to third aspects, wherein the discharge port is not included in a mist space floating in the vicinity of one surface of the object to be processed. It is arranged in.

  In the present invention, the mist sprayed from the discharge port is guided by the exhaust means so as to drift in the vicinity of one surface of the object to be processed, thereby suppressing variations in the in-plane temperature distribution on the surface of the object to be processed. As a result, variation in the film thickness distribution of the formed thin film can be reduced.

  Hereinafter, an embodiment of a film forming apparatus according to the present invention will be described with reference to the drawings.

1 and 2 are diagrams schematically showing a film forming apparatus of the present invention.
A film forming apparatus 1 according to the present invention is a film forming apparatus that forms a thin film on a target object 2 by spray pyrolysis, and includes a supporting unit 11 for placing the target object 2 and the target object 2. At least a discharge means 12 for spraying the mist 3 made of the raw material solution of the thin film and an exhaust means 13 having an exhaust port 13a in the vicinity of the object 2 to be processed. .

And in the film-forming apparatus 1 of this invention, the exhaust means 13 exhausts the mist 3 sprayed toward the center vicinity of the one surface of the to-be-processed body 2 from the discharge means 12, and exhausts the one surface vicinity of the to-be-processed body 2 by evacuating. Invite to drift.
As a result, the mist 3 sprayed toward the vicinity of the center of the object to be processed 2 flows over the object to be processed 2 from the center to the periphery as shown in FIG. 3, and is exhausted from the exhaust port 12a. . For this reason, the dispersion | variation in the in-plane temperature distribution of the to-be-processed object 2 surface can be suppressed. As a result, variation in the film thickness distribution of the formed thin film can be reduced.

  Further, if an excessive spray is floating in the space between the discharge means 12 and the object to be processed 2, the suspended matter is crystallized before reaching the object to be processed 2, and this becomes foreign matter on the object to be processed 2. Adhere to. In the film forming apparatus 1 of the present invention, the mist is not hindered by the suspended matter by forcibly exhausting the surplus spray that is floating by the exhaust means 13. Thereby, generation | occurrence | production of a foreign material can be suppressed.

  The support means 11 incorporates a temperature control means having heating, holding and cooling functions for the object to be processed 2 in order to form a thin film while keeping the film formation surface of the object to be processed 2 at a predetermined temperature. The temperature control means is, for example, a heater.

The discharge means 12 has its discharge port 12a disposed near the center of one surface of the object to be processed 2 and above it.
The discharge means 12 is a nozzle, for example. The raw material solution sprayed from the discharge means 12 is mist 3 (liquid fine particles).
The mist 3 may be generated by spraying the raw material solution in advance in the adjustment chamber 20 described later.

The discharge means 12 sprays the mist 3 onto the object 2 to be processed disposed in the space of the film forming chamber 10. The discharge port 12a is arranged at a position (height) that is not included in the mist space floating in the vicinity of one surface of the object 2 to be processed. The mist 3 is sprayed from the discharge port 12a at a flow rate of 100 to 100,000 cm / min. The distance between the discharge port 12a and the surface of the object to be processed 2 is controlled to be 5 to 200 mm.
Further, the surface of the object to be processed 2 is heated by heat transfer from the temperature control means, and is controlled in a temperature range of 200 to 600 ° C.

Further, it is preferable that the space including the object to be processed 2 and the discharge unit 12 is wrapped with a hood 14.
The hood 14 is made of a corrosion-resistant metal such as stainless steel. Openings are formed on both sides near the bottom.

  In the film forming apparatus 1, the hood 14 is disposed so as to wrap around the space between the object to be processed 2 disposed at a position facing the discharge unit 12, so that it is sprayed from the discharge port 12 a of the discharge unit 12. The sprayed raw material solution can be stably kept sprayed in the radial space from the discharge port 12a toward the object to be processed 2 without being affected by the outside air. In other words, the hood 14 also functions to prevent the raw material solution from being scattered from the internal space to the outside of the apparatus, thereby increasing the amount of uselessness, and thus the raw material solution is effectively used for forming a thin film.

  In addition, since the hood 14 is disposed so as to wrap between the ejection unit 12 and the target object 2, heat radiation from the target object 2 can be suppressed during film formation. As a result, the amount of heat required for heating the object to be processed 2 can be reduced, and the controllability of the surface temperature of the object to be processed 2 is improved.

The exhaust means 13 guides the mist 3 sprayed from the discharge port 12a so as to float around one surface of the object 2 to be processed.
As shown in FIG. 1 and FIG. 2, the exhaust port 13 a is preferably located in the vicinity of the outer periphery of the workpiece 2 and on the side or upper side thereof. By providing the exhaust port 13a on the side or upper side of the object 2 to be processed, the suspended matter can be removed without being involved.

  Moreover, it is preferable to provide a plurality of exhaust ports 13a. In the example shown in FIG. 2, the case where four exhaust ports 13a are provided is shown as an example. Further, it is preferable that the plurality of exhaust ports 13 a are provided at positions symmetrical with respect to the workpiece 2. By providing the plurality of exhaust ports 13a at symmetrical positions with respect to the object to be processed 2, the exhaust is performed more uniformly, and the variation in the in-plane distribution of the surface temperature of the object to be processed 2 can be more effectively suppressed. it can. Moreover, the entrainment of the suspended matter in the formed thin film can be further reduced. FIG. 2 shows a case where four exhaust ports 13a are provided so as to surround the periphery of the substrate at intervals of 90 °.

Further, the film forming apparatus 1 includes an adjustment chamber 20 that generates the mist 3 by spraying a raw material solution in advance, and a transport unit that includes a space for moving the mist 3 from the adjustment chamber 20 to the discharge unit 12. May be further provided.
In the adjustment chamber 20, the raw material solution is preliminarily sprayed by a spraying means different from the discharge means 12, and only small droplets (fine) droplets are efficiently taken out as mist 3 and sorted so as to equalize the size. I do. Since a finer mist can be sprayed, a film having good characteristics can be formed.
The generated mist 3 preferably contains 60.0 to 98.8 vol% of air.

The conveyance means has a conveyance path 21 as a space for conveying the generated mist 3 while guiding it.
The conveyance path 21 is isolated from the outside by a partition member, and is controlled so that the temperature of the inner wall is the same as or higher than that of the mist 3 and the temperature at which the evaporation rate of the solvent of the raw material solution does not become extreme. That is, there is a relationship of mist temperature < conveying path inner wall temperature < solvent evaporation temperature.

And the mist 3 in the conveyance path 21 has a flow rate of 100 to 100,000 cm / min.
Also. The inner wall of the conveyance path 21 is isolated from the outside by adopting a water repellent material such as a fluororesin, or by applying a treatment for imparting water repellency to the surface. At this time, if the conveyance path 21 is made of a material having good thermal conductivity such as metal, it is easily affected by the outside air temperature, which leads to adhesion of the mist 3 to the inner wall of the conveyance path. It is preferable to employ a resin material having a low thermal conductivity such as a fluororesin. In addition, when employ | adopting a metal material, it can respond by performing temperature control of a conveyance path outer wall.

In addition, when using hydrochloric acid, sulfuric acid, nitric acid, etc. as the chemical solution, it is necessary to use a chemical resistant material on the inner wall that is in direct contact with the mist 3 or to apply a surface treatment with a chemical resistant material. Become.
Furthermore, it is desirable that the distance of the transport path 21 is as short as possible. However, considering that the distance may be required from the viewpoint of design such as the mist temperature, the inner wall temperature, and restrictions on the arrangement of each means, it is desirable that the distance is less than 10 m.

Next, a method for forming a thin film on the object 2 by spray pyrolysis using the film forming apparatus 1 will be described.
In the following description, a case where an ITO film is formed as a transparent conductive film on a substrate that is the object to be processed 2 by using the film forming apparatus 1 of the present invention will be described as an example. The present invention is not limited to this and can be used to form various thin films.

First, a substrate having a clean surface is placed on a base plate, and the substrate is held together with the base plate in a predetermined position.
As the substrate, for example, a glass plate having a thickness of about 0.3 to 5 mm made of glass such as soda glass, heat-resistant glass, or quartz glass is preferably used.
When the substrate surface temperature reaches a predetermined temperature and stabilizes, the ITO film formation is started.

In the adjustment chamber 20, the raw material solution of the ITO film is preliminarily sprayed by the spraying means to form the mist 3.
As the raw material solution for the ITO film, a solution containing a component that becomes a conductive metal oxide such as tin-added indium (ITO) when heated is suitably used.
As the raw material solution for the ITO film, 0.01 mol of tin chloride / pentahydrate is added to an aqueous solution containing 0.2 mol / L of indium chloride / tetrahydrate, or an ethanol solution, and further an ethanol-water mixed solution. An aqueous solution containing / L, an ethanol solution, or an ethanol-water mixed solution is preferably used.

  The mist 3 generated in the adjustment chamber 20 is transported to the film forming chamber 10 via the transport path 21 and sprayed onto the substrate from a spray nozzle (discharge means 12) disposed on the upper portion of the film forming chamber 10. The When the mist 3 adheres to the surface of the substrate heated to a predetermined temperature, the solvent in the mist rapidly evaporates and the remaining solute rapidly undergoes a chemical reaction to change into a conductive metal oxide such as ITO. To do. Thereby, the crystal | crystallization which consists of an electroconductive metal oxide produces | generates rapidly on the surface of a board | substrate, and will form a transparent conductive film (ITO film | membrane) in a short time.

As shown in FIG. 3, the mist 3 sprayed from the discharge port 12a to the vicinity of the center of the substrate is guided by the exhaust means 13 and flows so as to drift on the substrate from the center portion toward the peripheral portion. Exhausted from.
When the ITO film is formed, the substrate is cooled until the substrate temperature reaches a predetermined temperature, and the substrate is taken out.
As described above, a transparent conductive film made of an ITO film is formed on the substrate.

In this film forming apparatus 1, the film forming chamber 10 for spraying the mist 3 is surrounded by a partition wall (upper surface and surroundings), and an exhaust port 13a for exhausting the mist 3 sprayed onto the substrate is provided. 3 can be controlled. For this reason, the dispersion | variation in the temperature distribution in a board | substrate surface is suppressed. Further, by providing the exhaust port 13a and controlling the mist flow, it is possible to suppress foreign matter from being mixed into the thin film.
As a result, the transparent conductive film thus obtained has a suppressed variation in film thickness distribution, and for example, in-plane uniformity of thin film characteristics such as conductivity is ensured. In addition, contamination with foreign matter is suppressed, and thereby a high quality product with excellent characteristics is obtained.
Furthermore, by controlling the mist flow, it was possible to prevent mist from adhering to members such as partition walls and nozzles in the film forming chamber, and to reduce the time required for maintenance for cleaning.

The film forming apparatus of the present invention has been described above, but the present invention is not limited to the above example, and can be appropriately changed as necessary.
For example, in the above description, the case where four exhaust ports are provided has been described as an example. However, the present invention is not limited to this, and the number of exhaust ports may be three or less. There may be five or more. Further, the arrangement of the exhaust ports is not limited to the above example.

An ITO film was formed as a transparent conductive film on the substrate using the film forming apparatus of the present invention.
First, a raw material solution was prepared as follows.
<Preparation of ITO raw material solution>
Indium (III) chloride pentahydrate (InCl ₃ · 4H ₂ O) 5.58 g / 100 ml and tin (IV) chloride pentahydrate (SnCl ₄ · 5H ₂ O) in a ratio of 0.36 g / 100 ml Prepared by dissolving in water.

(Example)
<ITO film formation>
A 500 mm × 500 mm × 2 mm borosilicate glass substrate (TEMPAX # 8330) was placed on the support and heated from room temperature to a surface temperature of 350-400 ° C. In addition, the heating method was based on the heat ray irradiation from the infrared lamp distribute | arranged to the food | hood upper part in addition to the heat transfer from the heating substrate distribute | arranged to the lower part of the glass substrate.
After confirming that the substrate surface temperature was stable, ITO film formation was started.
The ITO raw material solution is pre-sprayed in the adjustment chamber to form mist (liquid fine particles). Table 1 shows the mist conditions in the adjustment chamber and the conveyance path. In addition, the vinyl chloride bellows pipe which has a stretching property was employ | adopted for the conveyance path, and the Teflon (trademark) resin coat was given to the inner wall, and water repellency was ensured.

In the film formation chamber, four slit-type spray nozzles (nozzle outlet size: 7 × 270 mm) were arranged in a square shape, and the mist of the ITO raw material solution conveyed from the adjustment chamber was sprayed onto the substrate. At this time, the mist temperature at the nozzle outlet was 40 ° C., and the mist flow rate at the nozzle outlet was 22500 cm / min.
In order to realize 500 mm square film formation, the distance between the spray nozzle and the glass substrate is 20 mm, and the spray concentration is biased by ± 150 mm in the X direction on the substrate side and ± 150 mm in the Y direction on the nozzle side. It was prevented. The time required for forming the ITO film was 15 minutes.
Further, in the film forming chamber, four exhaust ports were provided so as to surround the periphery of the substrate at intervals of 90 °, and exhausted from four directions.

(Comparative example)
In the comparative example, an ITO film was formed on the glass substrate in the same manner as in the example except that a film forming apparatus having an open structure in both the film forming chamber and the exhaust structure was used without providing a hood.
An ITO film was formed on the glass substrate as described above.

  Table 2 shows a comparison between the heating substrate set temperature during film formation and the actual temperature of the glass substrate surface.

  As is clear from Table 2, in the example in which the hood is arranged so as to wrap between the discharge means and the substrate, the heat radiation from the substrate is suppressed as compared with the comparative example performed by the open system, and at the time of film formation It was possible to maintain the film forming temperature condition (300 to 450 ° C.) even under the condition that the substrate set temperature was lowered.

  Table 3 shows a comparison of the characteristics of the substrates on which the ITO films were formed in the examples and the comparative examples.

  As is apparent from Table 3, in the example, the spatial flow and temperature distribution of the substrate is suppressed by controlling the upward flow by evacuating and controlling the mist flow on the substrate surface. As a result, the film thickness and the sheet resistance distribution were made uniform.

  In addition, the number of foreign matters of 0.1 mm or more present on the surface of the formed ITO film was counted after forming 10 sheets and after forming 20 sheets. The results are shown in Table 4.

  As can be seen from Table 4, in the example, the mist flow is controlled to suppress the mist from adhering to the constituent members of the film forming chamber, and as a result, even after 10 and 20 films are formed on the film forming substrate. The generation of foreign matter of 0.2 mm or more was suppressed.

  The present invention can be applied to a film forming apparatus for forming a thin film such as a transparent conductive film by a spray pyrolysis method.

It is a figure which shows typically an example of the film-forming apparatus which concerns on this invention. It is a figure which shows arrangement | positioning of an exhaust port from the upper surface in the film-forming apparatus shown in FIG. It is a figure which shows typically the mist flow at the time of forming into a film using the film-forming apparatus which concerns on this invention. It is a figure which shows typically an example of the conventional film-forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Film-forming apparatus, 2 to-be-processed object, 3 mist, 10 film-forming chamber, 11 support means, 12 discharge means, 12a discharge port, 13 exhaust means, 13a exhaust port, 14 hood, 20 adjustment chamber, 21 conveyance path.

Claims (4)

A film forming apparatus for forming a thin film on one surface of an object to be processed by spray pyrolysis,
A support means for placing the object to be processed;
A discharge means for spraying a mist made of the raw material solution of the thin film toward a central area of one surface of the object to be processed;
And at least an exhaust means provided with an exhaust port in the vicinity of the object to be processed,
The discharge means has its discharge port disposed near the center of one surface of the object to be processed and in the vicinity of the upper portion thereof.
The exhaust means guides the mist sprayed from the discharge port so as to float near one surface of the object to be processed ,
A hood that encloses a space including the object to be processed and the discharge means;
The exhaust port is in the vicinity of the outer periphery of the object to be processed, and is arranged on the side or upper side thereof.
The apparatus comprises an adjustment chamber for generating the mist by spraying the raw material solution in advance, and a transfer means comprising a space for moving the mist from the adjustment chamber to the discharge means, and the transfer means guides the generated mist. While having a transport path as a space to transport while
Film formation characterized in that the temperature of the mist, the temperature of the inner wall of the transfer path, and the evaporation temperature of the solvent of the raw material solution are in the relationship of mist temperature <temperature of the inner wall of the transfer path <solvent evaporation temperature apparatus. The film forming apparatus according to claim 1, comprising a plurality of the exhaust ports. The film forming apparatus according to claim 2 , wherein the plurality of exhaust ports are provided at positions symmetrical to the object to be processed. The discharge opening is deposited according to any one of claims 1 to 3, characterized in that the is arranged at a position not included in the mist space drifting one surface near the object to be processed (height) apparatus.

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