JP6447008B2 - Film forming apparatus and film forming method - Google Patents

Description

  The present invention relates to a film forming apparatus and a film forming method useful for forming an inorganic salt.

  Conventionally, a technique for forming a hydroxide film on a substrate has been studied. Patent Document 1 describes that an oriented hydroxide film is formed on a substrate, and in the examples, a hydroxide film is formed by a spray method (spray method). However, the method of Patent Document 1 cannot be put into practical use in terms of the adhesion of the hydroxide film, and is not satisfactory in terms of film homogeneity, and still has many problems.

  On the other hand, a mist CVD method is known as a metal oxide film forming method. Patent Documents 2 to 5 describe that a metal oxide film is formed from a metal salt or a metal complex using a mist CVD method. In addition, as described in Non-Patent Document 1, film formation of various metal oxides by the mist CVD method has been studied. However, since the mist CVD method is considered to be suitable for the formation of an oxide film, its application to the film formation of a metal hydroxide or other metal salt film has not been studied much, and examples of examination are also included. Absent.

JP-A-6-256959 JP2012-073011A JP 2014-72533 A Japanese Patent No. 5398794 Patent No. 5528612

Kentaro Kaneko, “Growth and Physical Properties of Corundum Structure Gallium Oxide Mixed Crystal Thin Films”, Kyoto University Doctoral Dissertation, March 2013

  SUMMARY OF THE INVENTION An object of the present invention is to provide a film forming apparatus and a film forming method that are excellent in adhesion between an inorganic salt film and a substrate and can form a homogeneous inorganic salt film industrially advantageously.

  As a result of intensive studies to achieve the above object, the inventors of the present invention have found that an atomization unit that atomizes a raw material compound in a solvent, a conveyance unit that conveys mist generated by the atomization unit to a substrate with a carrier gas, and In the film forming apparatus including a film forming unit that heat-treats the mist to form a film on the substrate, the atomizing unit includes an atomizing unit that atomizes the inorganic salt as the raw material compound, and the film forming unit In addition, when the inorganic salt has a thermal oxidation temperature at a temperature equal to or higher than the vaporization temperature of the solvent, a film forming apparatus including a heat treatment means for heating the mist at a temperature lower than the thermal oxidation temperature, When an inorganic salt is formed, the obtained inorganic salt is excellent in adhesion to the substrate, a homogeneous inorganic salt film can be formed on various substrates, and industrially advantageous. Such a film forming apparatus has been described above. It found that can solve the conventional problems at a stroke.

That is, the present invention relates to the following inventions.
[1] An atomizing unit for atomizing a raw material compound in a solvent, a conveying unit for conveying mist generated by the atomizing unit to a substrate with a carrier gas, and forming a film on the substrate by heat-treating the mist. In the film forming apparatus including a film unit, the atomizing unit includes an atomizing unit that atomizes the inorganic salt as the raw material compound, and the film forming unit has a temperature equal to or higher than a vaporization temperature of the solvent, and When the inorganic salt has a thermal oxidation temperature, the film forming apparatus includes a heat treatment means for heating the mist at a temperature lower than the thermal oxidation temperature.
[2] The film forming apparatus according to [1], wherein the inorganic salt is a metal salt.
[3] The film forming apparatus according to [2], wherein the metal salt is a metal hydroxide.
[4] The film forming apparatus according to [2] or [3], wherein the metal salt is an alkali metal salt or an alkaline earth metal salt.
[5] The film forming apparatus according to any one of [1] to [4], wherein the raw material compound is a calcium compound.
[6] The film forming apparatus according to any one of [1] to [5], wherein the solvent includes water.
[7] The film forming apparatus according to [5], wherein the heat treatment is performed at a temperature of 200 ° C. to 500 ° C.
[8] In the method in which a mist generated by atomizing a raw material compound in a solvent is conveyed to a substrate with a carrier gas, and the mist is heat-treated to form a film on the substrate, the raw material compound is an inorganic salt, A film forming method, wherein the heat treatment is performed at a temperature equal to or higher than a vaporization temperature of the solvent and, when the inorganic salt has a thermal oxidation temperature, at a temperature lower than the thermal oxidation temperature.
[9] The film forming method according to [8], wherein the inorganic salt is a metal salt.
[10] The film forming method according to [9], wherein the metal salt is a metal hydroxide.
[11] The film forming method according to [9] or [10], wherein the metal salt is an alkali metal salt or an alkaline earth metal salt.
[12] The film forming method according to any one of [8] to [11], wherein the raw material compound is a calcium compound.
[13] The film forming method according to any one of [8] to [12], wherein the solvent includes water.
[14] The film forming method according to [12], wherein the heat treatment is performed at a temperature of 200 ° C. to 500 ° C.
[15] A film obtained by the film forming method according to any one of [8] to [14].

  The film forming apparatus of the present invention is excellent in the adhesion between the inorganic salt film and the substrate, and has the effect of forming a homogeneous inorganic salt film industrially advantageously.

The block diagram of the mist CVD apparatus used in the Example of this invention is shown.

  The film forming apparatus of the present invention includes an atomization unit that atomizes a raw material compound in a solvent, a conveyance unit that conveys mist generated by the atomization unit to a substrate with a carrier gas, and heat-treats the mist on the substrate. In the film forming apparatus including the film forming unit for forming a film, the atomizing unit includes an atomizing means for atomizing the inorganic salt as the raw material compound, and the film forming unit has a vaporization temperature equal to or higher than the vaporization temperature of the solvent. When the inorganic salt has a thermal oxidation temperature at a temperature, a heat treatment means for heating the mist at a temperature lower than the thermal oxidation temperature is provided.

  Further, the film forming method of the present invention is a method in which a mist generated by atomizing a raw material compound in a solvent is conveyed to a substrate with a carrier gas, and the mist is heat-treated to form a film on the substrate. Is an inorganic salt, and the heat treatment is performed at a temperature equal to or higher than the vaporization temperature of the solvent, and when the inorganic salt has a thermal oxidation temperature, it is performed at a temperature lower than the thermal oxidation temperature.

  The raw material compound is not particularly limited as long as it is an inorganic salt, but in the present invention, the inorganic salt is preferably a calcium compound. The inorganic salt is preferably a metal salt, and the metal salt is more preferably a metal hydroxide. The metal salt is preferably an alkali metal salt or an alkaline earth metal salt. Examples of the alkali metal salt or alkaline earth metal salt include hydroxides, carbonates, alkoxides, carboxylates, phosphates, azides, octanoates, naphthenates of alkali metals or alkaline earth metals, and the like. Is mentioned. More specifically, for example, hydroxides such as calcium hydroxide, lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, magnesium hydroxide, strontium hydroxide, lithium carbonate, sodium carbonate, Carbonates such as potassium carbonate, rubidium carbonate, cesium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, such as lithium methoxide, sodium matoxide, potassium methoxide, rubidium methoxide, cesium methoxide, calcium methoxide, magnesium methoxide Alkoxides such as sodium ethoxide, potassium ethoxide, etc., carboxylates such as sodium acetate, potassium acetate, sodium oxalate, potassium oxalate, etc., phosphates such as sodium phosphate, Azide such as lithium azide, sodium azide, potassium azide, rubidium azide, cesium azide, diazide magnesium, diazide calcium, diazidostrontium, lithium octoate, sodium octoate, potassium octoate, rubidium octoate Octanoates such as cesium octoate, magnesium bisoctanoate, calcium bisoctanoate, strontium bisoctanoate, such as lithium naphthenate, sodium naphthenate, potassium naphthenate, rubidium naphthenate, cesium naphthenate, magnesium naphthenate, calcium naphthenate, Examples thereof include naphthenates such as strontium naphthenate. In the present invention, the metal salt is preferably an alkali metal or alkaline earth metal hydroxide, and more preferably an alkaline earth metal hydroxide.

  In the present invention, the raw material compound is usually mixed with a solvent and used for atomization in liquid or sol form. Examples of the solvent include water and / or organic solvents (for example, alcohols such as methanol, ethanol, propanol, isopropyl alcohol, butanol, monomethoxyethanol, and ethylene glycol monomethyl ether; ketones such as acetone and methyl ketone, or a mixture thereof. In the present invention, the solvent preferably contains water, and is preferably water or a mixed solvent of water and alcohol.

  The mixing ratio of the mixed solution of the raw material compound and the solvent is preferably 0.01 to 60% by mass of the raw material compound and 0.1 to 50% by mass of the metal halide salt with respect to the mixed solution. Is more preferable.

  The substrate is not particularly limited as long as it can support the inorganic salt 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 material, which may be an organic compound or an inorganic compound. In the present invention, a uniform film can be obtained regardless of the shape of the substrate, and therefore it can be applied to substrates having various shapes. Examples of the shape of the substrate include plate shapes such as flat plates and discs, fiber shapes, rod shapes, columnar shapes, prismatic shapes, cylindrical shapes, spiral shapes, spherical shapes, fine particle shapes, ring shapes, and the like. In the substrate, a substrate is preferable. Although the thickness of a board | substrate is not specifically limited in this invention, Preferably, it is 10-2000 micrometers, More preferably, it is 50-800 micrometers.

  The substrate may be an insulator substrate or a conductive substrate such as a semiconductor substrate or a conductor substrate. In the present invention, the substrate is preferably an insulator substrate. The substrate material is not particularly limited as long as the object of the present invention is not impaired, and may be a known material. Examples of the insulator substrate include a glass substrate, a ceramic substrate, a quartz substrate, and a sapphire substrate. Examples of the semiconductor substrate include a silicon-based semiconductor substrate containing Si, SiGe, SiC, and the like, a gallium-based semiconductor substrate containing GaAs, GaN, GaP, and the like, InP, InAs, and the like. An indium-based semiconductor substrate can be used. Moreover, as a conductor board | substrate, the conductor board | substrate etc. in which a metal, stainless steel, etc. are contained are mentioned, for example.

  In the present invention, the substrate is preferably a glass substrate. This is because the dimensional change with respect to heat and temperature / humidity is smaller, and the resistance to the treatment liquid used in the post-process and the versatility are high. The glass substrate is preferably an alkali-free glass substrate, and examples of such a suitable alkali-free glass substrate include an aluminosilicate glass substrate, an aluminoborosilicate glass substrate, and a barium borosilicate glass substrate.

  The film forming apparatus of the present invention includes an atomization unit that atomizes a raw material compound in a solvent, a conveyance unit that conveys mist generated by the atomization unit to a substrate with a carrier gas, and heat-treats the mist on the substrate. A film forming unit for forming a film is provided. The said atomization part will not be specifically limited if the said raw material compound in the said solvent can be atomized. In the present invention, it is preferable that the atomizing unit includes at least an ultrasonic vibrator and has means for atomizing the raw material compound by ultrasonic vibration. The said conveyance part will not be specifically limited if the mist generated by the said atomization part can be conveyed to a base | substrate with the said carrier gas. The film forming section heat-treats the mist to form a film on the substrate.In the present invention, when the inorganic salt has a thermal oxidation temperature at a temperature equal to or higher than the vaporization temperature of the solvent, Heat treatment means for heating the mist at a temperature lower than the thermal oxidation temperature is provided.

  In the present invention, the raw material compound in the solvent is atomized using the film forming apparatus (atomization step), the generated mist is conveyed to the substrate with a carrier gas (conveying step), and the mist is heat-treated. Then, a film is formed on the substrate (film forming process).

  In an atomization process, the raw material compound in a solvent is atomized and mist is generated. The atomizing means is not particularly limited as long as it can atomize the raw material solution, and may be a known atomizing means, but in the present invention, it is preferably an atomizing means using ultrasonic waves. By using ultrasonic waves, a film having better adhesion can be formed.

  In the transfer step, the mist is supplied to the substrate by the carrier gas. The type of the carrier gas is not particularly limited as long as the object of the present invention is not impaired. For example, an inert gas such as oxygen, ozone, nitrogen or argon, or a reducing gas such as hydrogen gas or forming gas is preferable. As mentioned. Further, the type of carrier gas may be one type, but may be two or more types, and a diluent gas (for example, a 10-fold diluted gas) whose carrier gas concentration is changed is used as the second carrier gas. Further, it may be used. 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 film forming step, the mist is reacted by heat to form a film on part or all of the substrate surface. The thermal reaction is not particularly limited as long as it does not involve oxidation. In this step, the thermal reaction is usually carried out at a temperature equal to or higher than the vaporization temperature of the solvent and, if the inorganic salt has a thermal oxidation temperature, at a temperature lower than the thermal oxidation temperature. In this invention, it is preferable to perform the said heat processing at the temperature of 200 to 500 degreeC, and it is preferable to carry out at 250 to 400 degreeC. Further, the thermal reaction may be performed under any atmosphere of a vacuum, a non-oxygen atmosphere, a reducing gas atmosphere, and an oxygen atmosphere as long as the object of the present invention is not impaired. An atmosphere is preferred. This is because the film formation can be advantageously carried out industrially by carrying out in an oxygen atmosphere. Further, it is preferable to carry out the reaction under atmospheric pressure because the film can be formed advantageously industrially. The film thickness can be set by adjusting the film formation time.

  As described above, the inorganic salt film obtained by a suitable film forming method has excellent adhesion to the substrate, and a uniform film can be formed.

  Examples of the present invention will be described below.

<Example 1>
First, the CVD apparatus 19 used in this example will be described with reference to FIG. The CVD apparatus 19 adjusts the flow rate of the carrier gas sent from the sample stage 21 on which the film-formed sample 20 such as an insulator substrate is placed, the carrier gas source 22 that supplies the carrier gas, and the carrier gas 22. A flow rate adjusting valve 23, a mist generating source 24 for storing a raw material solution 24a, a container 25 for containing water 25a, an ultrasonic transducer 26 attached to the bottom surface of the container 25, and a quartz tube having an inner diameter of 40 mm. A film forming chamber 27, and a heater 28 installed around the film forming chamber 27. The sample stage 21 is made of quartz, and the surface on which the deposition target sample 20 is placed is inclined from the horizontal plane. Both the film formation chamber 27 and the sample stage 21 are made of quartz, so that impurities derived from the apparatus are prevented from being mixed into the thin film formed on the film formation target sample 20.

  An aqueous calcium hydroxide solution (concentration: 0.02 g / L) was used as a raw material solution. This raw material solution 24 a was accommodated in the mist generating source 24. Next, a glass substrate having a square with a side of 10 mm and a thickness of 600 μm is placed on the sample stage 21 as the film formation sample 20, and the heater 28 is operated to raise the temperature in the film formation chamber 27 to 350 ° C. The temperature was raised. Next, the flow rate adjusting valve 23 is opened to supply the carrier gas from the carrier gas source 22 into the film forming chamber 27, and the atmosphere in the film forming chamber 27 is sufficiently replaced with the carrier gas. Adjusted to min. Oxygen gas was used as the carrier gas.

Next, the ultrasonic vibrator 26 was vibrated at 2.4 MHz, and the vibration was propagated to the raw material solution 24a through the water 25a, whereby the raw material solution 24a was made into fine particles to produce raw material fine particles.
The raw material fine particles were introduced into the film forming chamber 27 by the carrier gas and reacted in the film forming chamber 27 to form a thin film on the film forming sample 20. When the composition of the obtained thin film was examined, it was calcium hydroxide.

<Comparative Example 1>
A calcium hydroxide film was formed on the substrate in the same manner as in Example 1 except that the film was formed using a spray spray instead of the mist CVD apparatus.

<Test Example 1>
The adhesion between the thin film obtained in Example 1 and Comparative Example 1 and the substrate was evaluated. Those that could be peeled by hand were evaluated as “×”, those that could be peeled using a metal cutting tool were evaluated as “Δ”, and those that could not be peeled off were evaluated as “◯”. The results are shown in Table 1.

  From Table 1, the film of Example 1 was not peeled at all from the substrate and had good adhesion. Further, the film of Comparative Example 1 was peeled off immediately and had no adhesion.

  The film forming apparatus and film forming method of the present invention are excellent in film forming quality, and are applicable to various fields such as semiconductors (for example, compound semiconductor electronic devices), electronic parts / electric equipment parts, optical / electrophotographic related apparatuses, industrial members, etc. Can be used.

DESCRIPTION OF SYMBOLS 19 Mist CVD apparatus 20 Film-forming sample 21 Sample stand 22 Carrier gas source 23 Flow control valve 24 Mist generation source 24a Raw material solution 25 Container 25a Water 26 Ultrasonic vibrator 27 Deposition chamber 28 Heater

Claims (4)

In the method of transporting mist generated by atomizing a raw material compound in a solvent to a substrate with a carrier gas, and heat-treating the mist to form a film on the substrate, the raw material compound is a metal hydroxide , and the solvent Includes water, and the heat treatment is performed at a temperature equal to or higher than the vaporization temperature of the solvent, and when the metal hydroxide has a thermal oxidation temperature, the heat treatment is performed at a temperature lower than the thermal oxidation temperature. A film forming method. The film forming method according to claim 1, wherein the metal hydroxide is an alkali metal hydroxide or alkaline earth metal. The film forming method according to claim 1 or 2, wherein the starting compound is a calcium compound. The film-forming method in any one of Claims 1-3 which perform the said heat processing at the temperature of 200 to 500 degreeC.