JP4315363B2 - Thin film formation method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a method of forming a thin film containing a crystalline metal oxide as a main component on a surface of a glass plate or the like by a thermal decomposition method. Furthermore, it is related with a base | substrate provided with the thin film formed by this method.
[0002]
[Prior art]
  A thin film containing a metal oxide such as tin oxide has an infrared reflecting function. A glass plate provided with this thin film is widely marketed as low emissivity glass because it reduces the transmittance of the total solar energy and does not allow indoor heat to escape to the outdoors. Moreover, this thin film can also exhibit an electromagnetic shielding function. As a method for producing such a glass plate, a thin film of a metal compound is formed using a chemical vapor deposition method (CVD method) or a thermal decomposition method such as a spray method in which a solution raw material or a solid raw material is sprayed on a high temperature glass surface. The method is known. For example, Patent Document 1 describes a method of forming a tin oxide thin film by supplying a gaseous reaction mixture containing an organotin compound, hydrogen fluoride, oxygen, and water to a high-temperature glass surface. Patent Document 2 describes a method of forming a tin oxide thin film by supplying vapor of an organic tin compound to the surface of a glass ribbon in a float bath in a float manufacturing method. When the organotin compounds described in these patent publications are used as a raw material for a thin film, there is an advantage that the thickness of the thin film can be easily uniformed. However, since an organic tin compound has a large environmental load such as a tributyltin compound, in recent years, it is desired to use a raw material in place of the organic tin compound. On the other hand, tin chloride has been widely used as a raw material for a thin film of tin oxide in the thermal decomposition method. For example, Patent Document 3 describes a method for forming a coating in which a first flow made of stannic chloride and a second flow made of water vapor are supplied onto glass in a turbulent state in a CVD method. Patent Document 4 describes a method of uniformly forming a thin film of tin oxide by premixing stannic chloride and water in a CVD method and supplying the mixture on a glass substrate in a laminar flow. ing.
[0003]
  A method for forming a thin film containing a metal oxide using such a thermal decomposition method is inferior in that it is difficult to make the film thickness uniform compared to a physical vapor deposition method such as a sputtering method. Since a thin film having a relatively uniform thickness can be formed in a short time, the method is suitable for mass production of industrial products. In the thermal decomposition method, the situation varies somewhat depending on the composition component of the raw material of the thin film, but generally, the higher the temperature of the reaction system, the higher the deposition rate. Therefore, in an industrial production process, it seems that the higher the formation temperature of the thin film, the better.
[0004]
[Patent Document 1]
Japanese National Patent Publication No. 11-509895
[Patent Document 2]
Japanese Examined Patent Publication No. 6-47482
[Patent Document 3]
JP-A-2-175561
[Patent Document 4]
Japanese Patent Laid-Open No. 9-40442
[0005]
[Problems to be solved by the invention]
  However, in the above pyrolysis method, when the metal oxide is crystalline, the thin film is formed by crystal growth, so that the state of crystal growth of the thin film is remarkably dependent on the surface state of the substrate on which the thin film is formed. Change. In other words, if there are many starting points for crystal growth on the surface of the substrate on which the thin film is formed, crystal growth starts from many points, so that the crystal growth, that is, the thickness of the thin film becomes relatively uniform. . On the other hand, if there are few starting points for crystal growth on that surface, when a highly reactive material is used, each crystal grows large before crystal nuclei are formed. Variations increase. Furthermore, it becomes difficult for the crystal to grow, and the film formation rate becomes slow. Further, in order to compensate for the delay in the film formation rate, if the thin film formation temperature is increased, the film thickness variation further increases. For example, the example of Patent Document 3 describes that a thin film of tin oxide is formed using stannic chloride at a glass temperature of 580 ° C. When a tin oxide thin film is formed under these conditions, there is no problem with the performance of the thin film except for the slow deposition rate. However, when the inventors conducted additional experiments, the glass temperature was increased to 615 ° C. When a thin film was formed, the glass surface became cloudy. When this white turbid portion was observed with an electron microscope, giant crystal grains reaching a diameter of 2 μm and a portion where no crystal grains existed on the side were observed. This is because, before the crystal nuclei are uniformly formed on the glass surface, the nuclei that were initially generated grew rapidly, and large irregularities were formed on the glass surface, and the haze ratio became very high macroscopically. It is thought that.
[0006]
  Further, in Example 25 of Patent Document 4, in the glass plate manufacturing process by the float method, a silicon oxide base film is formed on the glass ribbon using the CVD method, followed by a film formation rate of 6,234 nm / It is described that a tin oxide thin film was formed in min. However, since the surface of the silicon oxide base film is extremely smooth, when a thin film of tin oxide is formed at a film formation rate of 6,234 nm / min without any treatment, huge crystal grains are formed. It is apparent that white turbidity is produced. Incidentally, Patent Document 4 does not describe the surface state of the glass substrate of Example 25.
[0007]
  The present invention has been completed by paying attention to the above problems. An object of the present invention is to provide a forming method in which the thickness of the thin film becomes relatively uniform even if the crystalline metal oxide thin film is formed in a short time in a short time using a thermal decomposition method. is there. Furthermore, it is to prevent the substrate having the thin film from becoming clouded and to prevent the functional film formed on the thin film from being defective.
[0008]
[Means for Solving the Problems]
  To solve the above problem,The present invention
A method of forming a metal-containing thin film and a crystalline metal oxide thin film using a metal chloride as a raw material by a pyrolysis method on a glass ribbon in a float process,
Supplying a first mixed gas containing a metal chloride and an oxidation raw material from a first coater installed in a float bath to form the metal-containing thin film on the glass ribbon;
In the float bath, a second mixed gas containing a metal chloride and an oxidation raw material is supplied from a second coater disposed downstream of the first coater, and the crystalline metal oxide thin film is formed on the metal-containing thin film. Directly forming a film,
Provided is a thin film forming method in which each step is performed such that the deposition rate of the metal-containing thin film is slower than the deposition rate of the crystalline metal oxide thin film.
[0009]
[0010]
[0011]
[0012]
[0013]
[0014]
[0015]
[0016]
[0017]
[0018]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described in detail. Note that the present invention is not limited to the following embodiment.
[0019]
  The present invention relates to a method for forming a crystalline metal oxide thin film on a substrate by using a pyrolysis method, using a metal chloride as a raw material for the thin film, and forming the thin film on the substrate. The metal-containing thin film is preliminarily formed at a deposition rate slower than that of the crystalline metal oxide thin film so that the metal-containing particles are arranged in advance or in contact with the thin film. Here, the “metal-containing particle” refers to a mass containing a metal such as zinc, zirconium, indium, tin, or titanium and having a particle size of nanometer to submicrometer order. The metal-containing particles may be any of nitride, oxide, oxynitride or complex, and the shape is not particularly limited. The “metal-containing thin film” refers to a thin film formed from a metal chloride as a raw material by a thermal decomposition method and having a metal as the film material. The metal present as the film substance may be the metal-containing particles or may be included as a composition component of the thin film. The “crystalline metal oxide thin film” refers to a thin film mainly composed of a metal oxide having crystallinity such as tin oxide or titanium oxide. The “main component” means that the content of the composition component is 50% by mass or more according to common usage. Since the characteristics of the thin film are roughly determined by the main component, it is considered appropriate to judge the characteristics of the thin film using the main component.
[0020]
  As a result of intensive research focusing on the fact that the crystal growth state of the crystalline metal oxide thin film changes depending on the surface state of the substrate, the present inventors It has been found that the crystal growth of the metal oxide can be made relatively uniform over the entire thin film by preliminarily having a material that can be a starting point for crystal growth. What can be the starting point of this crystal growth is the metal-containing particles or the metal-containing thin film. The existence of these greatly increases the starting point of crystal growth of the metal oxide, and since crystal growth starts almost simultaneously from a large number of locations, the formation of large crystal grains of the crystalline metal oxide thin film is suppressed, As a result, the thickness of the thin film becomes relatively uniform.
[0021]
  In general, the higher the formation temperature, the higher the crystal growth rate, that is, the film formation rate of the crystalline metal oxide thin film. From the viewpoint of industrial production efficiency, the higher the formation temperature, the better. However, when this is done, the thickness of the crystalline metal oxide thin film becomes extremely uneven, and if the substrate is transparent, the appearance problem such as white turbidity may occur. This causes performance problems such as generation of defects. On the other hand, lowering the formation temperature of the crystalline metal oxide thin film has an advantage that the film formation speed becomes slow, but the film thickness becomes relatively uniform. Therefore, if a means for combining the advantages when the formation temperature is high and the advantages when the formation temperature is low can be found, the film thickness of the crystalline metal oxide thin film can be kept high and the film thickness can be made relatively uniform. It will be possible. The inventors of the present invention have come up with the present invention as a result of intensive studies on such means. The present invention effectively suppresses the expansion of pinholes and cloudy areas when the deposition rate of the crystalline metal oxide thin film is high, particularly when the temperature of the reaction system is high.
[0022]
  The metal-containing particles exist on the substrate and form convex portions there, and function as starting points for crystal growth. Further, when the metal-containing thin film contains metal-containing particles, the metal-containing thin film is provided with convex portions derived from the particles on the surface of the thin film. Since this metal oxide is attracted to promote crystal growth, it functions as a starting point for crystal growth.
[0023]
  The metal-containing particles preferably function as a nucleus for crystal growth and have an average particle size of 5 to 500 nm in order to suppress the generation of giant crystal grains in the crystalline metal oxide thin film. In addition, the method for disposing the metal-containing particles on the substrate is not particularly limited. However, in order to prevent the metal-containing particles from being uniformly and superimposed on the substrate, a method of fixing the substrate to a substrate heated at a high temperature by a powder spray method. Is preferred. Although it is desirable that the metal-containing particles have a single-layer close-packed structure on the substrate, they may function as nuclei for crystal growth, and therefore there may be some gaps between the particles. If the gap between the particles is 100 μm or less, it can contribute to the uniformity of the crystalline metal oxide thin film.
[0024]
  The metal of the metal-containing particles or the metal of the metal-containing thin film and the metal of the crystalline metal oxide thin film may be different metals, but are preferably the same type of metal. If these are the same kind of metal, crystal growth is further induced, so that the particle size of the metal-containing particles can be reduced or reduced, or the metal content in the metal-containing thin film can be reduced. For example, when a thin film made of tin oxide or titanium oxide having a rutile structure is formed as a metal-containing thin film, tin oxide or titanium oxide having the same rutile structure as the crystalline metal oxide thin film, or very similar to the rutile structure It is desirable to form a thin film made of titanium oxide having an anatase structure.
[0025]
  The metal-containing thin film may be formed directly on the substrate, or may be formed on a base film provided on the substrate. For example, when the substrate is made of glass, the base film is provided to prevent the alkali component contained in the glass from thermally diffusing into the metal-containing thin film and the crystalline metal oxide thin film. Silicon oxide, aluminum oxide, oxynitride It may be a dense thin film mainly composed of silicon or silicon oxycarbide, or if the adhesion strength between the substrate and the metal-containing thin film is low, it contains both components of the substrate and the metal-containing thin film. It may be a buffer layer that increases adhesion strength by affinity. Due to the presence of the base film, the metal-containing thin film or the crystalline metal oxide thin film can adhere to the substrate with sufficient strength, and its characteristics are hardly deteriorated.
[0026]
  Further, the base film may be composed of one layer or may be composed of two layers. For example, when the base film is composed of two layers, a thin film mainly composed of tin oxide or titanium oxide having a thickness of 20 to 80 nm is formed on the first layer closer to the substrate, and the second layer has a similar degree. It is preferable to use a thin film mainly composed of silicon oxide or aluminum oxide having a thickness. With such a two-layer structure, the interference color of the crystalline metal oxide thin film can be reduced.
[0027]
  When the first underlayer is a thin film mainly composed of tin oxide or titanium oxide, since these are crystalline thin films, minute irregularities are formed on the surface thereof. When the base is a glass containing an alkali component, if the metal chloride is used as a raw material when the first underlayer is formed by the thermal decomposition method, the alkali chloride particles are added along with the thermal decomposition of the raw material. Can be generated. By incorporating these particles into the first underlayer, a protruding portion protruding from the first underlayer can be formed, or by removing the generated particles by heat, a large recess can be formed in the first underlayer. it can. The surface irregularities of the first underlayer, and the protrusions and the recesses are directly reflected in the surface shape of the second amorphous underlayer such as silicon oxide. The surface shape of the second underlayer can function as a starting point for crystal growth of the metal-containing thin film so that the metal-containing particles or the metal-containing thin film function as the starting point for crystal growth of the crystalline metal oxide thin film. That is, if the surface of the base film is not flat, the deposition rate of the metal-containing thin film can be increased. Here, “the surface of the base film is not flat” means a state that can be clearly distinguished from the case where an amorphous base film is directly formed on a glass plate. Specifically, the surface of the base film has a thickness of 1 nm or more. It means that there is amplitude.
[0028]
  On the other hand, even if the substrate is glass, the base film is not necessarily required as long as it is aluminosilicate glass, borosilicate glass, quartz glass, or the like that does not contain an alkali component. However, as described above, a base film may be necessary for the purpose other than prevention of diffusion of the alkali component, and it is not excluded to provide the base film on glass containing no alkali component.
[0029]
  Glass containing no alkali component has higher thermal characteristics such as glass transition point than soda lime glass containing an alkali component, and can form a crystalline metal oxide thin film at a higher temperature. Further, since glass as a substrate is amorphous, the surface thereof is smooth, and the base film mainly composed of silicon oxide is also amorphous, and the surface thereof is smooth. On the smooth surface, there is no convex portion as a starting point for crystal growth, so it is necessary to provide a starting point for crystal growth by arranging metal-containing particles or forming a metal-containing thin film. Therefore, the present invention is particularly effective when a crystalline metal oxide thin film is formed on a glass substrate not containing an alkali component or on an amorphous base film thereon.
[0030]
  The method for forming the metal-containing thin film is not particularly limited as long as it is a thermal decomposition method, and examples thereof include a CVD method or a solution spray method in which a solution raw material is sprayed on a heated substrate. If the formation method of the metal-containing thin film and the crystalline metal oxide thin film are the same, they can be formed in a short time in a series of steps, so they are formed by the same method from the viewpoint of industrial production efficiency. It is preferable to do.
[0031]
  Since the metal-containing thin film must function as a starting point for crystal growth of the crystalline metal oxide thin film, the surface of the substrate or the base film is not uneven and is preferably formed with protrusions at regular intervals on the surface. There is a need. Therefore, the deposition rate of the metal-containing thin film is slower than the deposition rate of the crystalline metal oxide thin film. Specifically, a film formation rate of 20 to 2,500 nm / min is preferable. However, when the deposition rate exceeds 600 nm / min, it is preferable that irregularities are formed on the surface of the base film (second base layer).
[0032]
  As a means of making the film formation rate of the metal-containing thin film slower than the film formation rate of the crystalline metal oxide thin film, the surface temperature of the substrate or the base film is set lower to form the metal-containing thin film, and then heated again. Examples thereof include means for forming a crystalline metal oxide thin film, or means for using a raw material having low reactivity. However, when the base film, metal-containing thin film and crystalline metal oxide thin film are continuously formed on the glass ribbon in the float process by the CVD method, the reaction system temperature during the formation of the metal-containing thin film is higher than the crystalline metal. It becomes higher than the reaction system temperature at the time of forming the oxide thin film. In this case, in order to increase the reaction temperature of the crystalline metal oxide thin film, it may be possible to reheat the glass ribbon using a burner after forming the metal-containing thin film. May occur, and the glass formability may be impaired. Therefore, in this case, it is desirable to reduce the reactivity by changing the kind of the raw material, or to reduce the deposition rate by thinning the metal-containing thin film. In addition, as a metal chloride, in order to reduce environmental burden, the thing which does not contain organic substances, such as stannous chloride, stannic chloride, titanium chloride, zinc chloride, or indium chloride, is suitable.
[0033]
  The metal-containing thin film may contain metal-containing particles, or may contain metal as a composition component. For example, when a thin film mainly composed of a crystalline metal oxide such as tin oxide or titanium oxide is formed by a CVD method, a convex portion that can be clearly distinguished from other portions may be formed on the thin film. In some cases, fine irregularities are formed on the surface of the thin film, and the apex of the irregularities is interpreted as a convex part. That is, it may not be easy to determine whether or not the metal-containing particles are convex portions recognized by everyone. In the present invention, the metal-containing thin film only needs to function as a starting point of crystal growth, and even if it is not possible to clearly distinguish the apex of the surface unevenness or the convex portion, this is not a big problem as long as the function is satisfied. In addition, even when no clear protrusion is formed on the surface of the metal-containing thin film, it can function as a starting point of crystal growth when it can induce crystal growth of the crystalline metal oxide thin film.
[0034]
  In addition, when forming a metal-containing thin film by the CVD method, if the concentration of the metal-containing gas in the mixed gas that is the raw material is lowered, the film formation rate is increased and even if the film thickness is increased, white turbidity does not occur. It was confirmed. This is considered to be because if the concentration of the metal-containing gas is lowered, rapid crystal growth caused by local retention of the high-concentration metal-containing gas is suppressed.
[0035]
  The metal-containing thin film preferably has a thickness of 10 to 250 nm and a large number of convex portions having a height of 10 to 200 nm formed on the surface. If the thickness is less than 10 nm, the underlying film may not be completely covered. On the other hand, if the thickness exceeds 250 nm, the projections are large and too high, and large crystal grains are formed in the crystalline metal oxide thin film. The risk of generation increases. A more preferable thickness of the metal-containing thin film is 30 to 200 nm.
[0036]
  After arranging metal-containing particles or forming a metal-containing thin film by the above means, a crystalline metal oxide thin film is formed using a thermal decomposition method. In the crystalline metal oxide thin film, the crystal growth starts from many starting points due to the presence of the metal-containing particles or the metal-containing thin film, so that the film thickness hardly varies. Therefore, according to the method of the present invention, even if the deposition rate of the crystalline metal oxide thin film is increased, no large crystal grains are generated, so that a high-quality thin film without defects is formed while increasing the production efficiency. be able to.
[0037]
  The metal chloride, which is a raw material for the crystalline metal oxide thin film, is desirably in a gaseous state in the vicinity of the substrate. Therefore, in the midway route to the vicinity of the substrate, even in the liquid stateKamawaAbsent. That is, the CVD method for supplying a medium containing a metal chloride in a gas state is desirable, but a solution spray method in which the route is liquid or a powder spray method in a solid state may be used. In the CVD method, it is desirable to supply individual raw materials through separate paths so that gaseous metal chlorides and oxidizing raw materials react in the vicinity of the substrate. On the other hand, when the raw material is premixed in the middle of the supply path, a cloudy high haze state is likely to occur in a wide area of the crystalline metal oxide thin film at a low formation temperature. This is because, when premixed, the raw material in a gaseous state reacts before reaching the vicinity of the substrate, and when the starting point of crystal growth is small on the substrate, huge crystal grains are easily generated. Therefore, this invention exhibits its effect more effectively when the raw materials are premixed.
[0038]
  The method for forming the crystalline metal oxide thin film is not particularly limited as long as it is a thermal decomposition method, but a method capable of arranging the metal-containing particles or forming the metal-containing thin film in a series of steps is preferable. For example, after forming a metal containing thin film using CVD method, the method of forming a crystalline metal oxide thin film continuously is mentioned. However, in this case, since the formation temperature is lower than that at the time of forming the metal-containing thin film, it is desirable to use a reactive material such as tetrachloride as the raw material for the crystalline metal oxide thin film. Furthermore, if oxygen is excluded and water vapor is used as the main raw material as the oxidizing raw material, the decomposition of the metal chloride can be promoted, and the film formation rate can be increased.
[0039]
  In the case where the crystalline metal oxide thin film is formed in a plurality of times, for example, in the case of gradually forming a film using a plurality of coaters in the CVD method, the film forming speed by the raw material supplied from any one of the coaters However, if it is faster than the deposition rate of the metal-containing thin film, the effect of the present invention is exhibited.
[0040]
  If the metal-containing particles are arranged on the substrate or the metal-containing thin film is formed, the deposition rate of the crystalline metal oxide thin film can be increased to 2,700 nm / min or more, further to 3,500 nm / min or more. In particular, in a method of forming a base film, a metal-containing thin film and a crystalline metal oxide thin film in this order by a CVD method in a float bath using a glass ribbon in the float method as a base (hereinafter referred to as “online CVD method”). Can raise the reaction system temperature (surface temperature of the immediately preceding glass ribbon) when forming a crystalline metal oxide thin film to 615 ° C. or higher, and further to 620 ° C. to 750 ° C. The speed reaches as high as 6,300 to 20,000 nm / min. Even if the crystalline metal oxide thin film is formed at this film forming speed, the glass substrate does not become cloudy.
[0041]
  In the thermal decomposition method, it is preferable to use a compound of tin and titanium as a raw material for the metal-containing thin film and the crystalline metal oxide thin film. Examples of tin raw materials include stannic chloride, dimethyltin dichloride, dibutyltin dichloride, tetramethyltin, tetrabutyltin, dioctyltin dichloride, monobutyltin trichloride, and dibutyltin diacetate. In this case, the above-described effect is effectively achieved. Examples of the oxidation raw material used for forming tin oxide from the tin raw material include oxygen, water vapor, and dry air. When a thin film mainly composed of tin oxide is formed as the crystalline metal oxide thin film, an antimony or fluorine compound may be added to the raw material in order to improve the conductivity. Examples of the antimony compound include antimony trichloride and antimony pentachloride, and examples of the fluorine compound include hydrogen fluoride, trifluoroacetic acid, bromotrifluoromethane, and / or chlorodifluoromethane.
[0042]
  In the case of forming a base film by a thermal decomposition method, suitable silicon oxide materials for the base film include monosilane, disilane, trisilane, monochlorosilane, dichlorosilane, 1,2-dimethylsilane, 1,1,2-trimethyldisilane. 1,1,2,2-tetramethyldisilane, tetramethylorthosilicate, tetraethylorthosilicate, and the like. In this case, examples of the oxidation raw material include oxygen, water vapor, dry air, carbon dioxide, carbon monoxide, nitrogen dioxide, or ozone. In the case where silane is used, an unsaturated hydrocarbon gas such as ethylene, acetylene or toluene may be used in combination for the purpose of preventing the reaction of silane before reaching the glass surface. Similarly, examples of the aluminum raw material for forming aluminum oxide suitable as a base film include trimethylaluminum, aluminum triisopopropoxide, diethylaluminum chloride, aluminum acetylacetonate, and aluminum chloride. In this case, examples of the oxidation raw material include oxygen, water vapor, and dry air.
[0043]
  The type and shape of the substrate are not limited. Conventionally, any material having a crystalline metal oxide thin film can be used as it is. For example, if a crystalline metal oxide thin film is formed on a transparent substrate such as glass, the haze ratio of the glass substrate is reduced because there are no large crystal grains in the thin film. Therefore, the glass product provided with this thin film can effectively exhibit the electromagnetic shielding function, the heat ray reflecting function and the function as a conductive thin film derived from the crystalline metal oxide thin film without causing problems such as cloudiness. it can.
[0044]
  Hereinafter, embodiments according to the online CVD method will be described in more detail. In the apparatus used in the on-line CVD method, as shown in FIG. 1, a predetermined distance is separated from the surface of the glass ribbon 10 which flows out from the melting furnace (float kiln) 11 into the float bath 12 and moves in a strip shape on the tin bath 15. A predetermined number of coaters 16 (three coaters 16a, 16b, 16c in the illustrated form) are arranged in the tin float tank. From these coaters, a gaseous raw material is supplied, and a base film, a metal-containing thin film, and a crystalline metal oxide thin film are continuously formed on the glass ribbon 10. Although not shown, more coaters may be used, and the base film may be formed in two layers, or a crystalline metal oxide thin film may be formed by supplying raw materials from a plurality of coaters. The glass ribbon 10 on which the crystalline metal oxide thin film is formed is pulled up by a roller 17 and fed into the slow cooling furnace 13. The glass ribbon slowly cooled in the slow cooling furnace 13 is cut into a glass plate of a predetermined size by a cutting device (not shown). Note that the crystalline metal oxide thin film may be formed by spraying the glass ribbon coming out of the float bath 12 in combination with the CVD method in the float bath.
[0045]
  Even in the on-line CVD method, it is desirable to transport the material in the coater through separate paths so that the raw materials are mixed in the vicinity of the surface of the glass ribbon. However, according to the present invention, it is possible to premix and use the material. . When the raw materials are premixed and used, the reaction starts at an early stage in the coater, and large crystal grains are easily formed on the crystalline metal oxide thin film. In fact, in the conventional on-line CVD method, when tetrachloride is used as the metal chloride, when the raw material is premixed, the surface temperature of the glass ribbon is about 600 ° C. and white turbidity is generated. However, according to this invention, even if the raw material premixed on the glass ribbon having the surface temperature of 620 to 750 ° C. is supplied, the glass is not clouded. In addition, if the raw materials are premixed, there are many advantages in the industrial production process, such as easy temperature control until the raw material is supplied to the coater.
[0046]
【Example】
  Hereinafter, the present invention will be described specifically by way of examples. However, it is not limited to the following examples.
[0047]
(Reference example1)
  A 4 mm thick soda lime glass plate cut to 150 × 150 mm was placed on a mesh belt, passed through a heating furnace, and heated to about 600 ° C. While this heated glass plate is further conveyed, a mixed gas consisting of monosilane, oxygen and nitrogen is supplied from a coater installed above the conveyance path, and a thin film (underlayer film) made of silicon oxide having a film thickness of 25 nm on the glass plate. Formed. After this glass plate was slowly cooled, it was again placed on a mesh belt, passed through a heating furnace, and heated to about 620 ° C. While further transporting this heated glass plate, a mixed gas consisting of stannic chloride (steam), oxygen, water vapor and nitrogen is supplied from a coater installed above the transport path, and an oxide with a film thickness of 30 nm is formed on the underlying film. Tin (SnO₂) (Metal-containing thin film) was formed at a deposition rate of 50 nm / min. After this glass plate was slowly cooled, it was again placed on a mesh belt, passed through a heating furnace, and heated to about 620 ° C. While further transporting this heated glass plate, a mixed gas consisting of stannic chloride (steam), water vapor, nitrogen and hydrogen fluoride is supplied from a coater installed above the transport path, and a film is formed on the metal-containing thin film. 800nm thick fluorine-containing tin oxide (SnO₂: F) was formed as a transparent conductive film (crystalline metal oxide thin film) at a film formation rate of 670 nm / min. In addition, the distance between the coater and the glass plate was set to 10 mm, and nitrogen gas was supplied in the form of a curtain beside the exhaust part to prevent outside air from entering the coater during the formation of the transparent conductive film. This glass plate had a haze ratio of 22%, but no cloudiness was observed.
[0048]
(Reference example2)
  Reference exampleIn Example 1, a crystalline metal oxide thin film was formed in the same manner except that the following points were changed, and the glass plate was evaluated. The thickness of the base film is 20 nm, the thickness of the metal-containing thin film is 100 nm, the deposition rate is 160 nm / min, and the crystalline metal oxide thin film is oxygen-added to the raw material, and the thickness is 710 nm. In addition, the deposition rate was changed to 470 nm / min. This glass plate had a haze ratio of 17% and no cloudiness was observed.
[0049]
(Reference example3)
  Reference exampleIn Example 1, a crystalline metal oxide thin film was formed in the same manner except that the following points were changed, and the glass plate was evaluated. Aluminosilicate glass containing no alkali component is used for the glass plate, and for the metal-containing thin film, titanium chloride (vapor) is used as a metal chloride as a raw material, and a thin film made of titanium oxide having a thickness of 20 nm is formed at a deposition rate of 30 nm. / min. Further, regarding the crystalline metal oxide thin film, oxygen and methyl alcohol were added to the raw material, the thickness was changed to 900 nm, and the film formation rate was changed to 1,000 nm / min. This glass plate had a haze ratio of 29%, but no cloudiness was observed.
[0050]
(Reference example4)
  Reference exampleIn Example 1, a crystalline metal oxide thin film was formed in the same manner except that the following points were changed, and the glass plate was evaluated. With respect to the metal-containing thin film, oxygen as an oxidizing raw material was removed, and the film was formed to a film thickness of 30 nm at a film formation rate of 50 nm / min. In addition, regarding the crystalline metal oxide thin film, oxygen was added to the raw material, and the film was formed to a thickness of 400 nm at a film formation rate of 330 nm / min. This glass plate had a haze ratio of 6% and no cloudiness was observed.
[0051]
(Example1)
  Using an on-line CVD method, a base film, a metal-containing thin film, and a crystalline metal oxide thin film were formed in this order on a glass ribbon. Specifically, 98% by volume of nitrogen and 2% by volume of hydrogen were supplied into the float bath space so that the inside of the float bath was maintained at a slightly higher pressure than the outside of the bath. A mixed gas consisting of dimethyltin dichloride (steam), oxygen, nitrogen, and helium is supplied from the first coater located on the most upstream side while the float bath is maintained in a non-oxidizing atmosphere, and is placed on the glass ribbon. A 35 nm thick tin oxide thin film (first underlayer) was formed. Subsequently, a mixed gas composed of monosilane, ethylene, oxygen and nitrogen was supplied from the second coater to form a silicon oxide thin film (second underlayer) having a thickness of 25 nm on the tin oxide thin film. Further, a mixed gas composed of dimethyltin dichloride (steam), oxygen, water vapor and nitrogen is supplied from the third coater, and tin oxide (SnO) having a thickness of 100 nm is formed on the second underlayer having a surface temperature of 680 ° C.₂) (Metal-containing thin film) was formed at a deposition rate of 2,500 nm / min. Further, using a coater installed on the downstream side, a mixed gas consisting of stannic chloride (vapor), water vapor, nitrogen, helium and hydrogen fluoride is supplied onto the metal-containing thin film having a surface temperature of 630 ° C., and the film thickness is 670 nm. Fluorine-containing tin oxide (SnO₂: F) was formed at a film forming speed of 16,700 nm / min. This glass plate had a haze ratio of 17% and no cloudiness was observed.
[0052]
(Example2)
  Example1In Example 1, except that the following points were changed, a crystalline metal oxide thin film was formed and a glass plate was evaluated. The surface temperature of the metal-containing thin film was set to 660 ° C., and a crystalline metal oxide thin film having a thickness of 380 nm was formed at a deposition rate of 9,500 nm / min. This glass plate had a haze ratio of 6% and no cloudiness was observed.
[0053]
(Example3)
  Example1In Example 1, a mixed gas composed of stannic chloride (steam), water vapor, nitrogen, and helium was supplied from the first coater to form a 45-nm-thick tin oxide thin film (first underlayer) on the glass ribbon. Further, a mixed gas composed of stannic chloride (steam), oxygen, water vapor and nitrogen is supplied from the third coater, and tin oxide (SnO) having a thickness of 90 nm is formed on the second underlayer having a surface temperature of 680 ° C.₂) (Metal-containing thin film) was formed at a deposition rate of 1,830 nm / min. Further, using a coater installed on the downstream side, a mixed gas consisting of stannic chloride (vapor), water vapor, nitrogen, helium and hydrogen fluoride is supplied onto a metal-containing thin film having a surface temperature of 630 ° C., and the film thickness is 691 nm. Fluorine-containing tin oxide (SnO₂: F) was formed as a transparent conductive film (crystalline metal oxide thin film) at a film formation rate of 7,030 nm / min. The points not specified were the same as in Example 1. This glass plate had a haze ratio of 20% and no cloudiness was observed.
[0054]
(Example4)
  Using an on-line CVD method, a base film, a metal-containing thin film, and a crystalline metal oxide thin film were formed in this order on a glass ribbon. Specifically, 98% by volume of nitrogen and 2% by volume of hydrogen were supplied into the float bath space so that the inside of the float bath was maintained at a slightly higher pressure than the outside of the bath. A mixed gas composed of monosilane, ethylene, oxygen and nitrogen is supplied from the first coater located on the uppermost stream side in a state where the inside of the float bath is maintained in a non-oxidizing atmosphere, and silicon oxide having a thickness of 25 nm is formed on the glass. A thin film (underlying film) was formed. Further, a mixed gas composed of stannic chloride (steam), oxygen, water vapor and nitrogen is supplied from the second coater, and a 25 nm-thick tin oxide (SnO) film is formed on the base film having a surface temperature of 680 ° C.₂) (Metal-containing thin film) was formed at a deposition rate of 510 nm / min. Further, using a coater installed on the downstream side, a mixed gas composed of stannic chloride (vapor), water vapor, nitrogen, helium and hydrogen fluoride is supplied onto the metal-containing thin film having a surface temperature of 630 ° C., and the film thickness is 950 nm. Fluorine-containing tin oxide (SnO₂: F) was formed as a transparent conductive film (crystalline metal oxide thin film) at a film formation rate of 5,430 nm / min. This glass plate had a haze ratio of 18% and no cloudiness was observed.
[0055]
(Example5)
  Using an on-line CVD method, a base film, a metal-containing thin film, and a crystalline metal oxide thin film were formed in this order on a glass ribbon. Specifically, 98% by volume of nitrogen and 2% by volume of hydrogen were supplied into the float bath space so that the inside of the float bath was maintained at a slightly higher pressure than the outside of the bath. On the glass ribbon, a mixed gas consisting of stannic chloride (steam), water vapor, nitrogen and helium is supplied from the first coater located on the most upstream side while the float bath is maintained in a non-oxidizing atmosphere. A tin oxide thin film (first underlayer) having a thickness of 35 nm was formed on the substrate. Subsequently, a mixed gas composed of monosilane, ethylene, oxygen and nitrogen was supplied from the second coater to form a silicon oxide thin film (second underlayer) having a thickness of 25 nm on the tin oxide thin film. Further, a mixed gas composed of stannic chloride (steam), oxygen, water vapor and nitrogen is supplied from the third coater, and tin oxide (SnO) having a thickness of 140 nm is formed on the second underlayer having a surface temperature of 680 ° C.₂) (Metal-containing thin film) was formed at a film formation rate of 2,850 nm / min. Further, using a coater installed on the downstream side, a mixed gas composed of stannic chloride (vapor), water vapor, nitrogen, helium and hydrogen fluoride is supplied onto a metal-containing thin film having a surface temperature of 630 ° C., and the film thickness is 636 nm. Fluorine-containing tin oxide (SnO₂: F) was formed at a film forming rate of 6,470 nm / min. This glass plate had a haze ratio of 27% and no cloudiness was observed.
[0056]
(Comparative Example 1)
  Reference exampleIn Example 1, a thin film was formed on a glass plate in the same manner except that a crystalline metal oxide thin film was formed directly on a base film without forming a metal-containing thin film. The glass plate was clouded to the extent that it seemed to be rubbed glass.
[0057]
(Comparative Example 2)
  Reference exampleIn Example 1, a base film, a metal-containing thin film, and a crystalline metal oxide thin film were formed on a glass plate in the same manner except that the deposition rate of the metal-containing thin film was changed to 900 nm / min. This glass plate was more cloudy than the glass of Comparative Example 1.
[0058]
(Comparative Example 3)
  Example1In Example 1, except that the following points were changed, a crystalline metal oxide thin film was formed by an on-line CVD method, and a glass plate was evaluated. Without stopping the third coater and forming a metal-containing thin film, a transparent conductive film having a thickness of 600 nm was formed directly on the second underlayer at a deposition rate of 15,000 nm / min. This glass plate was more cloudy than Comparative Example 1. This is considered to be because a crystalline metal oxide thin film was formed on a glass ribbon having a high temperature of 630 ° C. in the online CVD method.
[0059]
(Comparative Example 4)
  Example1In Example 1, except that the following points were changed, a crystalline metal oxide thin film was formed by an on-line CVD method, and a glass plate was evaluated. On the second underlayer having a surface temperature of 690 ° C., a metal-containing thin film having a thickness of 600 nm was formed at a deposition rate of 15,000 nm / min. Furthermore, a crystalline metal oxide thin film having a film thickness of 300 nm was formed on a metal-containing thin film having a surface temperature of 650 ° C. at a film formation rate of 7,500 nm / min. White turbidity was observed on this glass plate.
[0060]
(Reference example5)
  Reference example1, a metal-containing thin film and a crystalline metal oxide thin film were formed on a glass plate in the same manner except that the base film was not formed. This glass plate had a haze ratio of 35% and was slightly cloudy.
[0061]
【The invention's effect】
  Since the present invention is configured as described above, the following effects can be obtained. According to this invention, even if the film formation rate of the crystalline metal oxide thin film is increased, the generation of giant crystal grains is suppressed. Therefore, even if this thin film is formed on a transparent substrate, white turbidity hardly occurs, and even if a functional film is formed on this thin film, defects are hardly generated. Therefore, if the thin film formation method of this invention is used, a base | substrate provided with a high quality crystalline metal oxide thin film can be manufactured efficiently.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an apparatus used in an on-line CVD method.
[Explanation of symbols]
10 Glass ribbon
11 Melting furnace
12 Float bath
13 Slow cooling furnace
16 Coater
17 Laura

Claims (8)

A method of forming a metal-containing thin film and a crystalline metal oxide thin film using a metal chloride as a raw material by a pyrolysis method on a glass ribbon in a float process ,
Supplying a first mixed gas containing a metal chloride and an oxidation raw material from a first coater installed in a float bath to form the metal-containing thin film on the glass ribbon;
In the float bath, a second mixed gas containing a metal chloride and an oxidation raw material is supplied from a second coater disposed downstream of the first coater, and the crystalline metal oxide thin film is formed on the metal-containing thin film. Directly forming a film,
A method of forming a thin film, wherein each step is performed such that a film forming rate of the metal-containing thin film is slower than a film forming rate of the crystalline metal oxide thin film . When the reactivity with the metal chloride is compared, the reactivity of the oxidation raw material contained in the first mixed gas is relatively low, and the reactivity of the oxidation raw material contained in the second mixed gas is relatively low The thin film formation method according to claim 1, which is expensive. The first mixed gas contains oxygen and water vapor as the oxidation raw material,
The thin film forming method according to claim 2, wherein the second mixed gas contains water vapor as the oxidation raw material and does not contain oxygen . The thin film forming method according to claim 1, wherein the first mixed gas and the second mixed gas contain stannic chloride as the metal chloride . The thin film formation method according to claim 1, wherein a deposition rate of the crystalline metal oxide thin film is 3,500 nm / min or more. Wherein prior to forming the metal-containing thin film, a thin film forming method according to claim 1, further comprising the step of forming a base film mainly containing silicon oxide on the glass ribbon. The thin film forming method according to claim 6 , wherein a surface of the base film is not flat. The thin film formation method according to claim 7 , wherein a deposition rate of the crystalline metal oxide thin film is 6,300 nm / min or more.

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