JP2017110287A - Film deposition method of inorganic oxide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film deposition method capable of depositing a high-quality inorganic oxide film simply, easily and industrially advantageously.SOLUTION: In a film deposition method, a first raw material solution 4a containing a precursor of an inorganic oxide and a second raw material solution 14a containing an oxide are atomized or changed into droplets respectively, and the obtained first mist or droplets 4b and second mist or droplets 14b are conveyed to a substrate 10 respectively by carrier gasses 2a, 12a, then, the first mist or droplets 4b and second mist or droplets 14b are thermally reacted together on the substrate 10 at a temperature below 200°C, to thereby deposit an inorganic oxide film on the substrate 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for forming an inorganic oxide film useful as a conductive film, a semiconductor film, an insulating film, a protective film, and the like.

Inorganic oxide films are used in various industries as conductive films, semiconductor films, insulating films, protective films, and the like. In particular, silicon oxide films are widely used as insulating films for electronic devices because they have very high insulating properties, and are also used in gate insulating films for MOS transistors, SiO ₂ cables, and high-performance LSI devices.
As a method for producing a silicon oxide film in the semiconductor field, a thermal oxidation method and a CVD method are known. The thermal oxidation method is the simplest method for producing a silicon oxide film, and a high-quality film can be obtained. However, since 800 ° C. to 1100 ° C. is necessary to promote thermal oxidation, there is a problem that it is limited only to the wafer process. Therefore, the CVD method is used for the gate insulating film of the MOS transistor, particularly in the process after the wafer process. The formation of a silicon oxide film using the CVD method is described in, for example, Patent Document 1. However, the CVD method also has a problem that the reaction in the gas phase part is dominant, an overhang is formed with respect to the base step, and the step coverage is deteriorated as the interlayer insulating film. Further, the CVD method has a problem that the raw material is limited to, for example, monosilane (SiH ₄ ) or the like which is very toxic or pyrophoric, and is not always satisfactory.

  In recent years, semiconductor devices using organic materials have attracted much attention. Typical examples include organic EL (OLED), organic transistor (OFET), organic thin film transistor (OTFT), organic thin film solar cell, and the like, and active research is being conducted all over the world. The characteristics of the organic semiconductor include flexibility, low cost, and large area. The organic EL element is considered to be deteriorated by moisture and oxygen, and a sealing film that covers the surface is required in order to prevent these intrusions in practical use. In forming a sealing film for an organic EL element, the organic material has low heat resistance, and therefore the film forming temperature is a serious problem. When applying a silicon oxide film, a technique capable of forming a film at a low temperature is required. Similarly, for an organic transistor or the like, it is desired to form a silicon oxide film as a gate insulating film at a low temperature.

  Recently, as a method for forming a silicon oxide film by the mist CVD method, a film forming method using ozone has been studied (Non-Patent Document 1). However, since this method uses ozone, it is not desirable in terms of safety and environmental sanitation, and there is a problem that a huge amount of equipment is required. In addition, since ozone is highly reactive and decomposes quickly, there is a problem that ozone must be generated immediately before use, and there is a problem in a film forming method that requires continuous ozone gas like mist CVD. It was not suitable. Therefore, there is a need for a film forming method that does not require the use of ozone gas and that enables low temperature film formation.

JP 2014-86445 A

Jinchun Piao et al., “Fabrication of Silicon Oxide Thin Films by Mist Chemical Vapor Deposition Method from Polysilazane and Ozone as Sources”, Japanese Journal of Applied Physics 51 (2012) 090201

  An object of the present invention is to provide a method capable of forming a low-temperature film without using ozone, and forming a high-quality inorganic oxide film industrially advantageously.

As a result of intensive studies to achieve the above-mentioned object, the present inventors have atomized or dropletized a raw material solution containing an inorganic oxide precursor, and transported the resulting mist or droplet to a substrate with a carrier gas. Then, if an inorganic oxide film is formed on the substrate by thermally reacting the mist or droplets on the substrate, a good quality inorganic oxide film can be easily formed at a low temperature without using ozone. It was found that the film can be easily formed, and it has been found that such a film forming method can solve the above-mentioned conventional problems all at once.
Moreover, after obtaining the said knowledge, the present inventors repeated investigation further, and came to complete this invention.

That is, the present invention relates to the following inventions.
[1] A raw material solution containing an inorganic oxide precursor is atomized or formed into droplets, and the obtained mist or droplets are conveyed to a substrate with a carrier gas, and then the mist or droplets are formed on the substrate. Is a method of forming an inorganic oxide film on the substrate, wherein the raw material solution contains an oxidizing agent, and the thermal reaction is performed at a temperature of less than 200 ° C. A film forming method.
[2] The film forming method according to [1], wherein the precursor is polysilazane having a repeating unit represented by the following formula (1).
(Wherein R ¹ , R ² and R ³ are the same or different and each represents a hydrogen atom, a halogen atom, a hydrocarbon group which may have a substituent or a heterocyclic ring which may have a substituent) Represents a group, and any two groups selected from R ¹ , R ² and R ³ may combine to form a ring.)
[3] The oxidizing agent is hydrogen peroxide, nitric acid, ammonium nitrate, ammonium sulfate, ammonium peroxodisulfate, potassium peroxodisulfate, perchloric acid, ammonium perchlorate, sodium perchlorate, potassium perchlorate, periodate The film forming method according to [1] or [2], which is one or more selected from sodium periodate, potassium periodate, methanesulfonic acid, sulfuric acid, and ethylenediamine sulfate.
[4] The film forming method according to any one of [1] to [3], wherein the carrier gas is an inert gas.
[5] The film forming method according to any one of [1] to [4], wherein the thermal reaction is performed in a non-oxygen atmosphere.
[6] The film forming method according to any one of [1] to [5], wherein the thermal reaction is performed at a temperature of 150 ° C. or lower.
[7] The first raw material solution and the second raw material solution are atomized or formed into droplets, respectively, and the obtained first mist or droplets and second mist or droplets are respectively transferred with a carrier gas. In this method, the first mist or droplet and the second mist or droplet are thermally reacted on the substrate to form an inorganic oxide film on the substrate. The first raw material solution contains an inorganic oxide precursor, the second raw material solution contains an oxidizing agent, and the thermal reaction is performed at a temperature of less than 200 ° C. Membrane method.
[8] The film forming method according to [7], wherein the first raw material solution contains polysilazane having a repeating unit represented by the following formula (1).
(Wherein R ¹ , R ² and R ³ are the same or different and each represents a hydrogen atom, a halogen atom, a hydrocarbon group which may have a substituent or a heterocyclic ring which may have a substituent) Represents a group, and any two groups selected from R ¹ , R ² and R ³ may combine to form a ring.)
[9] The oxidizing agent is hydrogen peroxide, nitric acid, ammonium nitrate, ammonium sulfate, ammonium peroxodisulfate, potassium peroxodisulfate, perchloric acid, ammonium perchlorate, sodium perchlorate, potassium perchlorate, periodic acid The film forming method according to [7] or [8], which is one or more selected from sodium periodate, potassium periodate, methanesulfonic acid, sulfuric acid, and ethylenediamine sulfate.
[10] The film forming method according to any one of [7] to [9], wherein the carrier gas is an inert gas.
[11] The film forming method according to any one of [7] to [10], wherein the thermal reaction is performed in a non-oxygen atmosphere.
[12] The film forming method according to any one of [7] to [11], wherein the thermal reaction is performed at a temperature of 150 ° C. or lower.
[13] An inorganic oxide film formed by the film forming method according to any one of [1] to [12].
[14] A semiconductor device including the inorganic oxide film according to [13].

  According to the film forming method of the present invention, a good quality inorganic oxide film can be obtained easily, simply and industrially advantageously at a low temperature without using ozone.

It is a schematic block diagram of the film-forming apparatus (mist CVD) used in the Example. It is a figure which shows the measurement result of the absorption spectrum in an Example. It is a figure which shows the evaluation result of the current-voltage characteristic in an Example. It is a figure which shows the evaluation result of the current-voltage characteristic in an Example. It is a figure which shows the measurement result of FT-IR in an Example. It is a figure which shows the measurement result of the refractive index in an Example. It is a figure which shows the measurement result of the film thickness in an Example.

  The inorganic oxide film forming method according to the present invention atomizes or droplets a raw material solution containing a precursor (atomization / droplet forming step), and transports the obtained mist or droplets to a substrate with a carrier gas. (Conveying step), and then thermally reacting the mist or droplets on the substrate to form an inorganic oxide film on the substrate (film forming step), wherein the raw material solution is oxidized And the thermal reaction is carried out at a temperature of less than 200 ° C.

(Atomization / droplet forming process)
In the atomization / droplet forming step, the raw material solution is atomized or dropletized. The atomizing means or the droplet forming means is not particularly limited as long as the raw material solution can be atomized or formed into droplets, and may be a known means, but in the present invention, the atomizing means using ultrasonic waves or A droplet forming means is preferred. Mist or droplets obtained using ultrasonic waves have a zero initial velocity and are preferable because they float in the air.For example, instead of spraying like a spray, they can be suspended in a space and transported as a gas. Since it is a possible mist, there is no damage due to collision energy, which is very suitable. The droplet size is not particularly limited and may be a droplet of several millimeters, but is preferably 50 μm or less, and more preferably 100 nm to 10 μm.

(Raw material solution)
The raw material solution is not particularly limited as long as it contains an inorganic oxide precursor and an oxidizing agent. An inorganic material may be included, and an organic material may be included. The raw material solution may contain both inorganic materials and organic materials. Examples of inorganic oxide precursors include alkoxides including metals such as Si, Ti, Zr, Al, Zn, Sn, W, Mo, Co, In, Sb, As, Yb, Sr, Th, and Ta, Known organic compounds or metal compounds such as metal complexes such as acetates and metal organic acid salts, metal salts, metal soaps and halides can be used, and these can be used alone or in combination.

  The inorganic oxide is not particularly limited as long as it is an oxide containing at least one inorganic element, and may be a known inorganic oxide. Examples of the inorganic oxide include the metal oxides, among which silica (silicon oxide), titania, alumina, zirconia, and zinc oxide are preferable, and silicon oxide is more preferable.

When the inorganic oxide is silicon oxide, a silicon-containing compound can be used as the precursor.
The silicon-containing compound is not particularly limited as long as it is a compound containing at least one silicon. Examples of the silicon-containing compound include silane, siloxane, silazane, and polysilazane. Examples of the silane include monosilane (SiH ₄ ) and alkoxysilane. Examples of the alkoxysilane include tetraethoxysilane (TEOS), tetramethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetraamyloxysilane, tetraoctyloxysilane, tetranonyloxysilane, dimethoxydiethoxysilane, dimethoxydiiso Examples thereof include propoxysilane, diethoxydiisopropoxysilane, diethoxydibutoxysilane, diethoxyditrityloxysilane, and mixtures thereof. Examples of the siloxane include hexamethyldisiloxane, 1,3-dibutyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, 1,3-divinyltetramethyldisiloxane, hexaethyldisiloxane and 3-glycidide. And xylpropylpentamethyldisiloxane. Examples of silazane include hexamethyldisilazane and hexaethyldisilazane.

  In the present invention, the silicon-containing compound is preferably polysilazane. The polysilazane is preferably a polysilazane having a repeating unit represented by the following formula (1), and more preferably a polysilazane having a repeating unit represented by the following formula (2). In the following formula (1) or (2), the average number of repetitions is not particularly limited as long as it is an integer, but is preferably 2 to 1000, more preferably 2 to 100, and 2 to 10. Most preferably.

(Wherein R ¹ , R ² and R ³ are the same or different and each represents a hydrogen atom, a halogen atom, a hydrocarbon group which may have a substituent or a heterocyclic ring which may have a substituent) Represents a group, and any two groups selected from R ¹ , R ² and R ³ may combine to form a ring.)

(In the formula, n is an average number of repetitions and is an integer.)

  The amount of the silicon-containing compound used is not particularly limited, but is preferably an amount that can be completely dissolved in a solvent. For example, it is preferable to dissolve the silicon-containing compound in a raw material solution including a solvent so as to have a concentration of about 0.01 to 50%, and to dissolve in a concentration of 0.1 to 30%. More preferably, it is most preferably dissolved to a concentration of about 1 to 10%.

  When the inorganic oxide is titania, a known titanium-containing compound such as titanium alkoxide can be used as the precursor. Examples of the titanium alkoxide include titanium trimethoxide, titanium triethoxide, titanium tri-n-propoxide, titanium tri-i-propoxide, titanium tri-n-butoxide, titanium tri-sec-butoxide, titanium tri-tert-butoxide, Examples thereof include tetraalkoxide titanium compounds such as isopropoxybis (ethyl acetoacetate) titanium, tetraisopropoxy titanium, tetra-n-butoxy titanium, and tetramethoxy titanium. The amount of titanium-containing compound used is not particularly limited, and may be the same as the amount of silicon-containing compound described above.

  When the inorganic oxide is alumina, for example, an aluminum-containing compound such as aluminum alkoxide can be used as the precursor. Examples of the aluminum alkoxide include trialkoxyaluminum compounds such as aluminum isopropylate, aluminum trisecondary butoxide, and monosec-butoxyaluminum diisopropylate. The amount of the aluminum-containing compound used is not particularly limited, and may be the same as the amount of the silicon-containing compound described above.

  Further, when the inorganic oxide is zirconia, a zirconium-containing compound such as zirconium alkoxide can be used as the precursor. Examples of the zirconium alkoxide include tetraalkoxy zirconium compounds such as diacetylacetone tributoxyzirconium and tetra-n-butoxyzirconium. The amount of the zirconium-containing compound used is not particularly limited, and may be the same as the amount of the silicon-containing compound described above.

  When the inorganic oxide is zinc oxide, a zinc-containing compound such as zinc alkoxide can be used as the precursor. Examples of the zinc-containing compound include dialkoxy zinc compounds such as zinc isopropinate, zinc disecondary butoxide, and monosec-butoxy zinc diisopropylate. The amount of zinc-containing compound used is not particularly limited, and may be the same as the amount of silicon-containing compound described above.

  The oxidizing agent is not particularly limited as long as the object of the present invention is not impaired, and may be a known oxidizing agent. Examples of the oxidizing agent include hydrogen peroxide, nitric acid, ammonium nitrate, ammonium sulfate, ammonium peroxodisulfate, potassium peroxodisulfate, perchloric acid, ammonium perchlorate, sodium perchlorate, potassium perchlorate, and iodine. Examples thereof include one or more selected from acids, sodium periodate, potassium periodate, methanesulfonic acid, sulfuric acid, and ethylenediamine sulfate. In the present invention, the oxidizing agent is preferably a hydrogen peroxide solution.

  The amount of the oxidizing agent used is not particularly limited, but is preferably an amount that can be completely dissolved in a solvent. For example, it is preferable to dissolve the oxidizing agent in a raw material solution including a solvent so as to have a concentration of about 0.1 to 70%, and more preferable to dissolve it in a concentration of about 1 to 50%. Most preferably, it is dissolved to a concentration of about 10 to 50%.

  In the present invention, a solution obtained by dissolving or dispersing the inorganic oxide precursor and the oxidizing agent in a solvent can be suitably used as the raw material solution. Examples of the solvent include organic solvents and inorganic solvents such as water. Examples of the organic solvent include ester solvents (eg, ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, propyl propionate, butyl propionate, etc.), ether solvents (eg, diethyl ether, tert-butyl methyl ether, Diglyme (eg, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether, diethylene glycol diethyl ether), 1,2-dimethoxyethane, tetrahydrofuran, etc.), amide solvent (eg, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone) 1,3-dimethyl-2-imidazolidinone, etc.), ketone solvents (for example, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, cyclopentanone, etc. ), Nitrile solvents (eg, acetonitrile, propionitrile, etc.), alcohol solvents (eg, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, etc.), halogenated solvents (eg, methylene chloride) , Chloroform, etc.) and aromatic solvents (for example, toluene, xylene, chlorobenzene, nitrobenzene, etc.), and the like, with ester solvents being preferred.

  The raw material solution can be obtained, for example, by mixing the inorganic oxide precursor and the oxidizing agent in the solvent. Further, in the present invention, it is preferable that the inorganic oxide precursor and the oxidizing agent are made into separate raw material solutions. For example, an inorganic oxide precursor is mixed with the solvent to form a first raw material solution, and the oxidizing agent is mixed with the solvent to form a second raw material solution. The raw material solution may contain various known additives, dopants, water and the like as long as the object of the present invention is not impaired.

(Conveying process)
In the transporting process, the mist or the droplets are transported to the substrate with a carrier gas. The carrier gas is not particularly limited as long as the object of the present invention is not impaired. For example, oxygen, ozone, an inert gas such as nitrogen or argon, or a reducing gas such as hydrogen gas or forming gas is preferable. Can be mentioned. Further, the type of carrier gas may be one, but it may be two or more, and a diluent gas with a reduced flow rate (for example, 10-fold diluted gas) is further used as the second carrier gas. Also good. Further, the supply location of the carrier gas is not limited to one location but may be two or more locations. The flow rate of the carrier gas is not particularly limited, but is preferably 0.01 to 20 L / min, and more preferably 1 to 10 L / min. In the case of a dilution gas, the flow rate of the dilution gas is preferably 0.001 to 2 L / min, and more preferably 0.1 to 1 L / min. In the present invention, the carrier gas is preferably an inert gas, more preferably nitrogen gas.
Further, when a plurality of raw material solutions are used, it is preferable that each mist or droplet is transported to the substrate with each carrier gas. For example, when the first raw material solution containing the inorganic oxide precursor and the second raw material solution containing the oxidizing agent are atomized or formed into droplets, respectively, the obtained first mist or The droplet and the second mist or droplet are each conveyed to the substrate with a carrier gas. Here, the first mist or droplet and the second mist or droplet may merge on the substrate, or may merge in the middle of reaching the substrate.

(Film formation process)
In the film forming step, an inorganic oxide film is formed on the substrate by thermally reacting the mist or droplets on the substrate at a temperature lower than 200 ° C. The thermal reaction may be performed as long as the mist or droplet reacts with heat at a temperature of less than 200 ° C. The reaction conditions are not particularly limited as long as the object of the present invention is not impaired. In this step, the thermal reaction is usually performed at less than 200 ° C., but is preferably 180 ° C. or less, and more preferably 150 ° C. or less. When the temperature is 100 ° C. or lower, not only can the film be formed at a low temperature, but a higher quality silicon oxide film can be obtained, and a silicon oxide film having a thick film, that is, 10 nm or more, preferably 20 nm or more can be easily obtained. Is obtained. The lower limit is not particularly limited as long as the object of the present invention is not impaired, but 20 ° C. or higher is preferable, and 30 ° C. or higher is more preferable. When the temperature is 50 ° C. or higher, a silicon oxide film having a higher refractive index can be obtained. Further, the thermal reaction may be performed under any atmosphere of vacuum, non-oxygen atmosphere, reducing gas atmosphere and oxygen atmosphere as long as the object of the present invention is not impaired. It is preferably performed in an atmosphere, and more preferably in a non-oxygen atmosphere. Moreover, although it may be performed under any conditions of atmospheric pressure, increased pressure, and reduced pressure, it is preferably performed under atmospheric pressure in the present invention. The film thickness can be set by adjusting the film formation time.

(Substrate)
The substrate is not particularly limited as long as it can support the inorganic oxide film. The material of the substrate is not particularly limited as long as the object of the present invention is not impaired, and may be a known substrate, an organic compound, or an inorganic compound. It may be a porous structure. The shape of the substrate may be any shape and is effective for all shapes, for example, a plate shape such as a flat plate or a disk, a fiber shape, a rod shape, a columnar shape, a prismatic shape, A cylindrical shape, a spiral shape, a spherical shape, a ring shape and the like can be mentioned. In the present invention, a substrate is preferable. Although the thickness of a board | substrate is not specifically limited in this invention, 10 micrometers-100 mm are preferable and 100 micrometers-10 mm are more preferable.

The substrate is not particularly limited as long as it is plate-shaped and serves as a support for the inorganic oxide film. It may be an insulator substrate, a semiconductor substrate, a metal substrate, or a conductive substrate. A substrate in which at least one of a metal film, a semiconductor film, a conductive film, and an insulating film is formed on part or all of these surfaces can also be suitably used as the substrate. . In the present invention, the substrate is preferably a glass substrate, and more preferably a glass substrate having at least one of a metal film, a semiconductor film, a conductive film and an insulating film on the surface. . Examples of the constituent metal of the metal film include one selected from gallium, iron, indium, aluminum, vanadium, titanium, chromium, rhodium, nickel, cobalt, zinc, magnesium, calcium, silicon, yttrium, strontium, and barium. Two or more kinds of metals may be mentioned. As a constituent material of the semiconductor film, for example, an elemental element such as silicon or germanium, a compound having an element of Group 3 to Group 5 or Group 13 to Group 15 of the periodic table, metal oxide, metal sulfide , Metal selenide, or metal nitride. Examples of the constituent material of the conductive film include tin-doped indium oxide (ITO), zinc oxide (ZnO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), tin oxide (SnO ₂ ), Examples thereof include indium oxide (In ₂ O ₃ ) and tungsten oxide (WO ₃ ). In the present invention, a conductive film made of a conductive oxide is preferable, and a tin-doped indium oxide (ITO) film is used. Is more preferable. Examples of the constituent material of the insulating film include aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), and silicon oxynitride (Si _4). O ₅ N ₃ ) and the like are mentioned, but an insulating film made of an insulating oxide is preferable, and a titania film is more preferable.

  Note that the means for forming the metal film, the semiconductor film, the conductive film, and the insulating film is not particularly limited, and may be a known means. Examples of such forming means include mist CVD, sputtering, CVD (vapor deposition), SPD (spray pyrolysis deposition), vapor deposition, ALD (atomic layer deposition), and coating ( For example, dipping, dripping, doctor blade, inkjet, spin coating, brush coating, spray coating, roll coater, air knife coating, curtain coating, wire bar coating, gravure coating, inkjet coating, and the like).

  In the present invention, it is preferable that the conductive film or the insulating film is formed on the substrate, and it is more preferable that the conductive film is formed on the substrate. In the present invention, the base preferably includes a tin-doped indium film.

  In the present invention, an inorganic oxide film may be provided directly on the substrate, or an inorganic oxide film may be provided via another layer such as a buffer layer (buffer layer) or a stress relaxation layer. . The means for forming other layers such as a buffer layer (buffer layer) and a stress relaxation layer is not particularly limited and may be a known means. In the present invention, the mist CVD method is preferable.

  By forming the inorganic oxide film as described above, a high-quality inorganic oxide film can be obtained easily and easily without using ozone. Moreover, the film thickness of the obtained inorganic oxide film can also be easily adjusted by adjusting the film formation time.

  The inorganic oxide film is useful for various applications as a conductive film, a semiconductor film, an insulating film, or a protective film. In the present invention, for example, when the inorganic oxide film is a silicon oxide film, the silicon oxide film is preferably used for a semiconductor device as an insulating film or a protective film. Examples of the semiconductor device include a semiconductor laser, a diode, or a transistor, and more specifically, a transistor such as a MIS or HEMT, a TFT, a Schottky barrier diode, a PIN diode, or a light emitting / receiving element. . In the present invention, the semiconductor device is preferably a diode or a transistor.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

Example 1
1. Film Forming Apparatus The mist CVD apparatus (1) used in this example will be described with reference to FIG. The mist CVD apparatus (1) includes a carrier gas source (2a, 12a) for supplying a carrier gas, and a flow rate adjusting valve (3a, 13a) for adjusting the flow rate of the carrier gas sent from the carrier gas source (2a, 12a). ), A mist generating source (4, 14) in which the raw solution (4a, 14a) is stored, a container (5, 15) containing water (5a, 15a), and a container (5, 15) An ultrasonic transducer (6, 16) attached to the bottom surface, a film formation chamber (7), a supply pipe (9, 19) connecting the mist generation source (4, 14) to the vicinity of the substrate (10), And at least a hot plate (8) installed in the film forming chamber (7). A substrate (10) is placed on the hot plate (8). In addition, there are two types of raw material solutions (4a, 14a), and carrier gas sources (2a, 12a), carrier gas (dilution) sources (2b, 12b), flow control valves (3a, 3b, 13a, 13b), respectively. , A mist generation source (4, 14), a container (5, 15), an ultrasonic transducer (6, 16), and a supply pipe (9, 19).

2. 2. Preparation of raw material solution 2-1. Preparation of first raw material solution Polysilazane and butyl acetate were mixed so that the concentration of polysilazane was 6.0% to obtain a first raw material solution.
2-2. Preparation of second raw material solution Hydrogen peroxide water and distilled water were mixed so that the concentration of hydrogen peroxide was 20.0% to obtain a second raw material solution.

3. Preparation of film formation The first raw material solution (4a) obtained in (1) was accommodated in the first mist generation source (4). In addition, the above 2. The second raw material solution (14a) obtained in (1) was accommodated in the second mist generation source (14). Next, a glass substrate with a 15 mm square ITO film was placed on the hot plate (8) as the substrate (10), and the hot plate (8) was operated to raise the temperature to 100 ° C. Next, the flow control valves (3a, 13a) are opened, and carrier gas is supplied from the carrier gas supply means (2a, 12a), which is a carrier gas source, into the film formation chamber (7). After sufficiently substituting the atmosphere with a carrier gas, the flow rate of the carrier gas was adjusted to 2 L / min. Nitrogen was used as the carrier gas.

4). Formation of Silicon Oxide Film Next, the ultrasonic vibrator (6, 16) is vibrated at 2.4 MHz, and the vibration is propagated to the raw material solution (4a, 14a) through water (5a, 15a). The solution (4a, 14a) was atomized to produce mist (4b, 14b). The mist (4b, 14b) is introduced into the film formation chamber (7) by the carrier gas through the supply pipes (9, 19), and is formed into the film formation chamber (7 at 100 ° C. under atmospheric pressure. ) Caused a thermal reaction to form a film on the substrate (10). The film formation time was 30 minutes.

5. Evaluation The film thickness, refractive index and absorption spectrum of the obtained silicon oxide film were measured by spectroscopic ellipsometry (manufactured by Horiba, Ltd., Auto SE). As a result, the film thickness was 64 nm. The refractive index was 1.485. The absorption spectrum is shown in FIG. From these results, it can be seen that a high-quality silicon oxide film was obtained.

  For the obtained silicon oxide film, a source meter (manufactured by TFF Keithley Instruments Co., Ltd., 2634B type source meter, 2 channels, (1 fA, 200 V, 1.5 A, DC / 10 A pulse), bench top version) is used. The current-voltage measurement was performed. The measurement was performed according to the following procedure. An electrode is formed on the substrate. As an anode electrode, a target of a sputtering apparatus (manufactured by EMITECH, K575X) was set to gold (Au), and a 6-point circular electrode having a diameter of 1.5 mm was formed. Later, the thin film at the end is peeled off using acetone, and a silver paste is applied to make the ITO film surface the cathode electrode. The electrode was contacted with a probe, voltage was applied, and the breakdown voltage was measured. The results are shown in FIG.

(Example 2)
A silicon oxide film was formed in the same manner as in Example 1 except that the film formation temperature was 150 ° C. Further, the current-voltage characteristics were evaluated in the same manner as in Example 1. The results are shown in FIG.

  As is clear from the results of the examples, the silicon oxide film obtained by the film forming method of the present invention is of good quality and has excellent electrical characteristics such as withstand voltage.

(Example 3)
A silicon oxide film was formed in the same manner as in Example 1 except that the film formation temperature was 22 ° C.

Example 4
A silicon oxide film was formed in the same manner as in Example 1 except that the film formation temperature was 50 ° C.

(Example 5)
A silicon oxide film was formed in the same manner as in Example 1 except that the film formation temperature was 70 ° C.

(Example 6)
Including reproducibility, the film formation temperature was set again to 100 ° C., and a silicon oxide film was formed in the same manner as in Example 1.

(Example 7)
A silicon oxide film was formed in the same manner as in Example 1 except that the film formation temperature was 120 ° C.

(Example 8)
A silicon oxide film was formed in the same manner as in Example 1 except that the film formation temperature was 150 ° C.

Example 9
A silicon oxide film was formed in the same manner as in Example 1 except that the film formation temperature was 170 ° C.

(Example 10)
A silicon oxide film was formed in the same manner as in Example 1 except that the film formation temperature was 200 ° C.

  About the silicon oxide film obtained in Examples 3-10, formation of the silicon oxide film was confirmed by FT-IR. The FT-IR chart is shown in FIG. FIG. 5 shows that a silicon oxide film has been formed. Moreover, the refractive index and film thickness of the silicon oxide films obtained in Examples 4 to 8 and Example 10 were measured. The measurement results for the refractive index are shown in FIG. 6, and the measurement results for the film thickness are shown in FIG. FIG. 6 shows that the silicon oxide film has a good refractive index when the temperature is 50 ° C. or higher. Further, it can be seen from FIG. 7 that when the temperature is 100 ° C. or less, the film formation rate is excellent and a thick film can be easily obtained.

  The inorganic oxide film obtained by the film forming method of the present invention can be used in various industries as a conductive film, a semiconductor film, an insulating film, or a protective film. For example, the silicon oxide film can be used as an insulating film in a semiconductor device. .

DESCRIPTION OF SYMBOLS 1 Mist CVD apparatus 2a (First) Carrier gas source 3a (First) Flow control valve 4 (First) Mist generation source 4a (First) Raw material solution 4b (First) Mist 5 (First 5) (First) Water 6 (First) Ultrasonic vibrator 7 Deposition chamber 8 Hot plate 9 (First) Supply tube 10 Substrate 12a (Second) Carrier gas source 13a (Second) (Second) mist generating source 14a (second) raw material solution 14b (second) mist 15 (second) container 15a (second) water 16 (second) Sonic transducer 19 (second) supply pipe

Claims (14)

  A raw material solution containing an inorganic oxide precursor is atomized or dropletized, and the resulting mist or droplet is conveyed to a substrate with a carrier gas, and then the mist or droplet is thermally reacted on the substrate. Then, an inorganic oxide film is formed on the substrate, wherein the raw material solution contains an oxidizing agent, and the thermal reaction is performed at a temperature of less than 200 ° C. Membrane method. The film forming method according to claim 1, wherein the precursor is polysilazane having a repeating unit represented by the following formula (1).
(Wherein R ¹ , R ² and R ³ are the same or different and each represents a hydrogen atom, a halogen atom, a hydrocarbon group which may have a substituent or a heterocyclic ring which may have a substituent) Represents a group, and any two groups selected from R ¹ , R ² and R ³ may combine to form a ring.)   Oxidizing agent is hydrogen peroxide solution, nitric acid, ammonium nitrate, ammonium sulfate, ammonium peroxodisulfate, potassium peroxodisulfate, perchloric acid, ammonium perchlorate, sodium perchlorate, potassium perchlorate, periodic acid, periodate The film forming method according to claim 1, wherein the film forming method is one or more selected from sodium iodate, potassium periodate, methanesulfonic acid, sulfuric acid, and ethylenediamine sulfate.   The film forming method according to claim 1, wherein the carrier gas is an inert gas.   The film forming method according to claim 1, wherein the thermal reaction is performed in a non-oxygen atmosphere.   The film forming method according to claim 1, wherein the thermal reaction is performed at a temperature of 150 ° C. or lower.   The first raw material solution and the second raw material solution are atomized or formed into droplets, respectively, and the obtained first mist or droplets and second mist or droplets are respectively transferred to the substrate with a carrier gas. A method of forming an inorganic oxide film on the substrate by thermally reacting the first mist or droplet and the second mist or droplet on the substrate; A method of forming an inorganic oxide film, wherein the first raw material solution contains a precursor of an inorganic oxide, the second raw material solution contains an oxidizing agent, and the thermal reaction is performed at a temperature of less than 200 ° C. The film-forming method of Claim 7 in which the 1st raw material solution contains the polysilazane which has a repeating unit represented by following formula (1).
(Wherein R ¹ , R ² and R ³ are the same or different and each represents a hydrogen atom, a halogen atom, a hydrocarbon group which may have a substituent or a heterocyclic ring which may have a substituent) Represents a group, and any two groups selected from R ¹ , R ² and R ³ may combine to form a ring.)   Oxidizing agent is hydrogen peroxide solution, nitric acid, ammonium nitrate, ammonium sulfate, ammonium peroxodisulfate, potassium peroxodisulfate, perchloric acid, ammonium perchlorate, sodium perchlorate, potassium perchlorate, periodic acid, periodate The film forming method according to claim 7, wherein the film forming method is one or more selected from sodium iodate, potassium periodate, methanesulfonic acid, sulfuric acid, and ethylenediamine sulfate.   The film forming method according to claim 7, wherein the carrier gas is an inert gas.   The film forming method according to claim 7, wherein the thermal reaction is performed in a non-oxygen atmosphere.   The film forming method according to claim 7, wherein the thermal reaction is performed at a temperature of 150 ° C. or less.   An inorganic oxide film formed by the film forming method according to claim 1. A semiconductor device comprising the inorganic oxide film according to claim 13.