JP2022119880A - Film deposition apparatus and film deposition method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film deposition apparatus excellent in deposition speed, to which a CVD method can be applied; and to provide a film deposition method excellent in deposition speed.

SOLUTION: A film deposition apparatus has an atomization part for generating mist by atomizing raw material solution, a carrier gas feeding part for feeding carrier gas for conveying mist, a film deposition part for depositing on a substrate by heat-treating mist, a conveyance part for connecting the atomization part to the film deposition part, and conveying mist by carrier gas, and conveyance part heating means for heating at least a part of the conveyance part.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a film forming apparatus and a film forming method for forming a film on a substrate using mist-like raw materials.

Conventionally, pulsed laser deposition (PLD), molecular beam epitaxy (MBE), sputtering method, etc. High vacuum film deposition equipment capable of realizing a non-equilibrium state has been developed. It has become possible to manufacture oxide semiconductors that could not be manufactured by the melt method or the like. In addition, a mist chemical vapor deposition (Mist CVD) method, in which crystals are grown on a substrate using atomized mist raw materials, has been developed. It has become possible to fabricate gallium oxide (α-Ga ₂ O ₃ ) with a corundum structure. As a semiconductor with a large bandgap, α-Ga ₂ O ₃ is expected to be applied to next-generation switching elements capable of achieving high withstand voltage, low loss and high heat resistance.

Regarding the mist CVD method, Patent Document 1 describes a tubular furnace type mist CVD apparatus. Patent Document 2 describes a fine channel type mist CVD apparatus. Patent Document 3 describes a linear source type mist CVD apparatus. Patent Document 4 describes a tubular furnace mist CVD apparatus, which differs from the mist CVD apparatus described in Patent Document 1 in that a carrier gas is introduced into the mist generator. Patent Document 5 describes a mist CVD apparatus which is a rotating stage in which a substrate is placed above a mist generator and a susceptor is mounted on a hot plate. Cited Document 6 describes a film forming apparatus and a film forming method for forming a film by heating aerosol in a heating tower attached to a nozzle provided close to directly above the substrate and spraying the aerosol onto the substrate.

JP-A-1-257337 Japanese Patent Application Laid-Open No. 2005-307238 JP 2012-46772 A Patent No. 5397794 JP 2014-63973 A Patent No. 4841338

Unlike other CVD methods, the mist CVD method does not require a high temperature and can produce a metastable phase crystal structure such as the corundum structure of α-gallium oxide. However, the inventor of the present invention condenses and aggregates in the supply pipe until the generated mist is conveyed to the substrate (reduced life of the mist), and the condensed mist is not sent to the film forming unit. A new problem was found in that the film formation rate was lowered.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a film forming apparatus which is excellent in film forming speed and to which a mist CVD method can be applied, and a film forming method which is excellent in film forming speed. and

The present invention has been made in order to achieve the above objects, and includes a misting unit for misting a raw material solution to generate a mist, a carrier gas supply unit for supplying a carrier gas for conveying the mist, and the mist. at least one of: a film-forming unit for heat-treating a substrate to form a film on a substrate; a conveying unit that connects the mist-generating unit and the film-forming unit and conveys the mist by the carrier gas; and a transport unit heating means for heating the film forming apparatus.

According to such a film forming apparatus, it is possible to extend the life of the mist in the conveying section and increase the film forming speed.

At this time, the film forming apparatus may further include a control section, and the control section may control the transfer section heating means to set the temperature of the transfer section to 30 to 120.degree.

As a result, the effect of improving the life of the mist before film formation can be further improved.

Further, a film forming method for forming a film by heat-treating mist in a film forming section, comprising a step of forming a mist from a raw material solution in a mist forming section to generate mist, and the mist forming section and the film forming section. a step of heating at least a part of a conveying section connecting the , a step of conveying the mist from the mist generating section to the film forming section via the conveying section by a carrier gas, and in the film forming section and heat-treating the mist to form a film on a substrate.

According to such a film forming method, it is possible to extend the life of the mist in the transport section and increase the film forming speed.

At this time, the temperature of the conveying section can be set to 30 to 120.degree.

As a result, the effect of improving the life of the mist before film formation can be further improved.

As described above, according to the film forming apparatus of the present invention, it is possible to greatly improve the film forming speed with a simple apparatus configuration. Moreover, according to the film forming method of the present invention, it is possible to greatly improve the film forming speed by a simple method.

1 is a schematic configuration diagram showing an example of a film forming apparatus of the present invention; FIG. It is a figure explaining an example of the misting part used for this invention. FIG. 4 is a schematic configuration diagram showing another example of the film forming apparatus of the present invention; FIG. 5 is a schematic configuration diagram showing still another example of the film forming apparatus of the present invention;

The present invention will be described in detail below, but the present invention is not limited to these.

As described above, in the mist CVD method, a film forming apparatus capable of improving the film forming speed and a film forming method capable of greatly improving the film forming speed have been desired.

As a result of intensive studies on the above problems, the inventors of the present invention have found a misting unit that mists a raw material solution to generate mist, a carrier gas supply unit that supplies a carrier gas for conveying the mist, and a mist generator. a film formation unit that performs heat treatment to form a film on a substrate; a transfer unit that connects the mist generation unit and the film formation unit and transfers the mist by the carrier gas; and at least part of the transfer unit. The inventors have found that the life of the mist in the conveying section can be extended and the film forming speed can be increased by a film forming apparatus having a conveying section heating means for heating, and the present invention has been completed.

In addition, as a result of extensive studies on the above problems, the present inventors have found a film formation method in which mist is heat-treated in a film formation unit to form a film, wherein the raw material solution is made into mist in the mist formation unit. heating at least a part of a conveying section connecting the mist generating section and the film forming section; and from the mist generating section to the film forming section via the conveying section, By a film forming method including a step of conveying the mist with a carrier gas and a step of heat-treating the mist in the film forming unit to form a film on a substrate, the life of the mist in the conveying unit is extended and the film is formed. The inventors have found that it is possible to increase the film speed, and completed the present invention.

Description will be made below with reference to the drawings.

Here, the term "mist" as used in the present invention refers to a general term for fine particles of liquid dispersed in gas, and includes what is called mist, liquid droplets, and the like.

FIG. 1 shows an example of a film forming apparatus 101 according to the present invention. The film forming apparatus 101 includes a mist generating unit 120 for generating mist by turning a raw material solution into a mist, a carrier gas supply unit 130 for supplying a carrier gas for transporting the mist, and a heat treatment for the mist to form a film on a substrate. A transport unit 109 that connects the film forming unit 140, the mist generating unit 120, and the film forming unit 140, transports the mist by a carrier gas, and a transport unit heating unit 111 that heats at least a part of the transport unit 109. have. Further, the operation of the film forming apparatus 101 may be controlled by including a control unit 117 that controls all or part of the film forming apparatus 101 . It is preferable that the control section 117 can control at least the conveying section heating means 111 .

(Misting part)
The mist generating unit 120 adjusts the raw material solution and mists the raw material solution to generate mist. The misting means is not particularly limited as long as it can mist the raw material solution, and may be a known misting means, but it is preferable to use a misting means using ultrasonic vibration. This is because mist can be made more stably.

An example of such a misting unit 120 is shown in FIG. For example, it may include a mist generation source 104 containing a raw material solution 104a, a container 105 containing a medium capable of transmitting ultrasonic vibrations, such as water 105a, and an ultrasonic transducer 106 attached to the bottom surface of the container 105. good. Specifically, a mist generation source 104, which is a container containing a raw material solution 104a, is contained in a container 105 containing water 105a using a support (not shown). An ultrasonic transducer 106 is provided at the bottom of the container 105, and the ultrasonic transducer 106 and the oscillator 116 are connected. When the oscillator 116 is operated, the ultrasonic vibrator 106 vibrates, ultrasonic waves propagate through the water 105a into the mist generation source 104, and the raw material solution 104a turns into mist.

(Carrier gas supply unit)
The carrier gas supply unit 130 has a carrier gas source 102a that supplies carrier gas, and may include a flow control valve 103a for adjusting the flow rate of the carrier gas sent from the carrier gas source 102a. In addition, a carrier gas source 102b for dilution that supplies a carrier gas for dilution and a flow control valve 103b for adjusting the flow rate of the carrier gas for dilution sent from the carrier gas source 102b for dilution can also be provided as needed. .

The type of carrier gas is not particularly limited, and can be appropriately selected according to the film to be deposited. Examples thereof include oxygen, ozone, inert gases such as nitrogen and argon, and reducing gases such as hydrogen gas and forming gas. Also, the number of carrier gases may be one, or two or more. For example, a diluent gas obtained by diluting the same gas as the first carrier gas with another gas (for example, diluted 10 times) may be further used as the second carrier gas, and air may also be used.
In addition, the carrier gas may be supplied at two or more locations instead of at one location.
The flow rate of carrier gas is not particularly limited. For example, when forming a film on a 30 mm square substrate, the flow rate is preferably 0.01 to 20 L/min, more preferably 1 to 10 L/min.

(Deposition part)
In the film forming section 140 , the mist is heated to cause a thermal reaction to form a film on part or all of the surface of the substrate 110 . The film-forming section 140 includes, for example, a film-forming chamber 107 , a substrate 110 is installed in the film-forming chamber 107 , and a hot plate 108 for heating the substrate 110 can be provided. The hot plate 108 may be provided outside the film forming chamber 107 as shown in FIG. 1, or may be provided inside the film forming chamber 107 . Further, the deposition chamber 107 is provided with an exhaust port 112 for exhaust gas at a position that does not affect the supply of mist to the substrate 110 .

In the present invention, the substrate 110 may be placed on the upper surface of the film forming chamber 107 to face down, or the substrate 110 may be placed on the bottom surface of the film forming chamber 107 to face up.
The thermal reaction is not particularly limited as long as the mist reacts by heating. It can be appropriately set according to the raw material and the film-formed material. For example, the heating temperature can be in the range of 120-600°C, preferably in the range of 200-600°C, more preferably in the range of 300-550°C.
The thermal reaction may be performed under vacuum, under a non-oxygen atmosphere, under a reducing gas atmosphere, under an air atmosphere, or under an oxygen atmosphere, and may be appropriately set according to the film to be deposited. In addition, the reaction pressure may be under atmospheric pressure, under increased pressure or under reduced pressure, but film formation under atmospheric pressure is preferable because the apparatus configuration can be simplified.

(Conveyor)
The conveying section 109 connects the mist forming section 120 and the film forming section 140 . Mist is transported by the carrier gas from the mist generation source 104 of the mist generating unit 120 to the film forming chamber 107 of the film forming unit 140 via the transport unit 109 . The transport section 109 can be, for example, a supply pipe 109a. As the supply pipe 109a, for example, a quartz pipe or a resin tube can be used.

(Transportation unit heating means)
The transport section heating means 111 is provided in the transport section 109 to heat the transport section 109 . The transport section heating means 111 is preferably provided over the entire transport section 109 as shown in FIG. 3 and 4 (reference numerals are omitted as appropriate), it may be provided only in a part of the supply pipe 109a of the transport section 109. FIG. The heating mechanism of the transport unit heating means 111 is not particularly limited, and any heating method such as resistance heating, high-frequency heating, and light heating using infrared rays or the like may be used.

Formally converting the water content in the pipe to the saturated water vapor content from the flow rate of the carrier gas and the flow rate of the mist indicates that the concentration of the mist in the pipe is supersaturated. Therefore, when the mist comes into contact with the wall of the piping with a low temperature, the mist easily condenses and agglomerates to form condensation (reduced life of the mist). become unable. That is, it causes a decrease in the film formation speed. In order to solve this problem, if the conveying section 109 is heated by the conveying section heating means 111, condensation and agglomeration of the mist can be suppressed, and as a result, the film forming speed can be increased.

The temperature for heating the conveying section 109 by the conveying section heating means 111 is preferably 30 to 120.degree. Within such a range, mist condensation and aggregation can be more effectively suppressed, and the film forming speed can be increased.
The adjustment of the heating temperature can also be controlled by providing the film forming apparatus 101 with a controller 117 .

(raw material solution)
The raw material solution is not particularly limited as long as it contains a material that can be misted, and may be an inorganic material or an organic material. Metals or metal compounds are preferably used, and those containing one or more metals selected from gallium, iron, indium, aluminum, vanadium, titanium, chromium, rhodium, nickel and cobalt can be used.
The raw material solution is not particularly limited as long as the metal can be misted. As the raw material solution, a solution in which the metal is dissolved or dispersed in an organic solvent or water in the form of a complex or a salt is preferably used. be able to. Examples of forms of the complex include acetylacetonate complexes, carbonyl complexes, ammine complexes, hydride complexes, and the like. Salt forms include, for example, metal chloride salts, metal bromide salts, and metal iodide salts. In addition, a solution obtained by dissolving the above metal in hydrobromic acid, hydrochloric acid, hydroiodic acid, or the like can also be used as an aqueous salt solution.

Additives such as hydrohalic acid and an oxidizing agent may be mixed in the raw material solution. Examples of the hydrohalic acid include hydrobromic acid, hydrochloric acid, hydroiodic acid, etc. Among them, hydrobromic acid and hydroiodic acid are preferable. Examples of the oxidizing agent include hydrogen peroxide (H ₂ O ₂ ), sodium peroxide (Na ₂ O ₂ ), barium peroxide (BaO ₂ ), benzoyl peroxide (C ₆ H ₅ CO) ₂ O ₂ and the like. , hypochlorous acid (HClO), perchloric acid, nitric acid, ozone water, and organic peroxides such as peracetic acid and nitrobenzene.

Furthermore, the raw material solution may contain a dopant. The dopant is not particularly limited. Examples include n-type dopants such as tin, germanium, silicon, titanium, zirconium, vanadium or niobium, or p-type dopants such as copper, silver, tin, iridium and rhodium. The dopant concentration may be, for example, about 1×10 ¹⁶ /cm ³ to 1×10 ²² /cm ³ , and even at a low concentration of about 1×10 ¹⁷ /cm ³ or less, about 1×10 ²⁰ /cm ³ or higher.

(substrate)
The substrate 110 is not particularly limited as long as it can form a film and can support a film. The material of the substrate 110 is also not particularly limited, and a known substrate can be used, and it may be an organic compound or an inorganic compound. Examples include polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyimide, polyetherimide, fluororesin, metals such as iron, aluminum, stainless steel, and gold, silicon, sapphire, quartz, glass, and gallium oxide. Examples include, but are not limited to. The shape of the substrate may be any shape, and is effective for all shapes. It may be cylindrical, helical, spherical, ring-shaped, etc. In the present invention, a plate-shaped substrate is preferred. The thickness of the plate-like substrate is not particularly limited, but is preferably 10-2000 μm, more preferably 50-800 μm.

Next, an example of the manufacturing method according to the present invention will be described below with reference to FIG.
First, the raw material solution 104a is contained in the mist generating source 104, the substrate 110 is placed on the hot plate 108 directly or through the wall of the film forming chamber 107, and the hot plate 108 is operated. Next, the transport section heating means 111 is activated to heat the supply pipe 109a of the transport section 109 . Next, the flow control valves 103a and 103b are opened to supply the carrier gas from the carrier gas sources 102a and 102b into the film forming chamber 107. After the atmosphere in the film forming chamber 107 is sufficiently replaced with the carrier gas, the carrier gas is supplied. Adjust the flow rate and the flow rate of the carrier gas for dilution. Next, the ultrasonic oscillator 106 is vibrated, and the vibration is propagated to the raw material solution 104a through the water 105a, thereby misting the raw material solution 104a to generate mist. Then, the mist is introduced into the film forming chamber 107 through the transport section 109 by carrier gas. At this time, the supply pipe 109a is heated to, for example, 30 to 120.degree. Therefore, the mist efficiently introduced into the film forming chamber 107 thermally reacts with the heat of the hot plate 108 in the film forming chamber 107 and forms a film on the substrate 110 at a high film forming rate.

EXAMPLES The present invention will be described in detail below with reference to examples, but these are not intended to limit the present invention.

(Example 1)
First, the film forming apparatus 101 used in this example will be described with reference to FIG. The film forming apparatus 101 includes a carrier gas source 102a that supplies a carrier gas, a flow control valve 103a that adjusts the flow rate of the carrier gas sent from the carrier gas source 102a, and a dilution carrier gas that supplies a dilution carrier gas. a source 102b, a flow control valve 103b for adjusting the flow rate of the carrier gas for dilution sent from the carrier gas source 102b for dilution, a mist generation source 104 containing a raw material solution 104a, and a container containing water 105a. 105, an ultrasonic oscillator 106 attached to the bottom surface of the container 105, a film formation chamber 107, a quartz supply pipe 109a connecting the mist generation source 104 to the film formation chamber 107, and a hot plate 108. ing. As the transfer section heating means 111, a ribbon heater JK-3 manufactured by AS ONE Co., Ltd. was wound around the entire supply pipe 109a so that the temperature could be controlled.

Next, a raw material solution was prepared. An aqueous solution of 0.1 mol/L of gallium bromide was prepared, and a 48% hydrobromic acid solution was added so as to be 10% by volume, and this was used as the raw material solution 104a.

The raw material solution 104 a obtained as described above was accommodated in the mist generation source 104 . Next, a 4-inch (100 mm diameter) c-plane sapphire substrate as the substrate 110 is placed adjacent to the hot plate 108 in the deposition chamber 107, and the hot plate 108 is operated to raise the temperature to 500°C. did.
Next, the temperature of the transfer section heating means 111 was adjusted to 80°C. Subsequently, the flow control valves 103a and 103b are opened to supply the carrier gas from the carrier gas sources 102a and 102b into the film formation chamber 107. After sufficiently replacing the atmosphere in the film formation chamber 107 with the carrier gas, the carrier gas is supplied. The flow rate was adjusted to 5 L/min, and the flow rate of the carrier gas for dilution was adjusted to 0.5 L/min. Oxygen was used as a carrier gas.

Next, the ultrasonic vibrator 106 was oscillated at 2.4 MHz, and the vibration was propagated to the raw material solution 104a through the water 105a, thereby misting the raw material solution 104a to generate mist. This mist was introduced into the film forming chamber 107 through the supply pipe 109a by the carrier gas. Then, a thin film of gallium oxide (α-Ga ₂ O ₃ ) having a corundum structure was formed on the substrate 110 by thermally reacting the mist in the film forming chamber 107 under atmospheric pressure and 500° C. conditions. The film formation time was 30 minutes.

The film thickness of the thin film on the substrate 110 was measured using a profilometer at 17 points in the plane of the substrate 110, and the average value was calculated from the respective film thickness values.
The average film thickness was 5.6 μm. Also, the film formation rate obtained by dividing the average film thickness by the film formation time was 11.2 μm/hour.

(Example 2)
Film formation was carried out under the same conditions as in Example 1, except that the temperature of the transfer section heating means 111 was set to 30.degree. The average film thickness was 5.5 μm, and the film formation rate was 11.0 μm/hour.

(Example 3)
Film formation was carried out under the same conditions as in Example 1, except that the temperature of the transfer section heating means 111 was set to 120.degree. The average film thickness was 5.1 μm, and the film formation rate was 10.2 μm/hour.

(Example 4)
A transport section heating means 111 was provided in the manner shown in FIG. That is, 60% of the entire supply pipe 109a was provided with the transfer section heating means 111 and heated. Film formation was performed under the same conditions as in Example 1 except for this. The average film thickness was 5.2 μm, and the film formation rate was 10.4 μm/hour.

(Example 5)
A transport section heating means 111 was provided in the manner shown in FIG. That is, the conveying section heating means 111 was installed and heated in a range of 30% of the entire supply pipe 109a. Film formation was performed under the same conditions as in Example 1 except for this. The average film thickness was 4.8 μm, and the film formation rate was 9.6 μm/hour.

(Comparative example 1)
Film formation was carried out under the same conditions as in Example 1 except that the temperature of the supply pipe 109a was kept at room temperature without providing the transfer unit heating means 111 . The average film thickness was 3.7 μm, and the film formation rate was 7.4 μm/hour.

A summary of the results of Examples 1-5 and Comparative Example 1 is shown in Table 1. In addition, in Comparative Example 1, since the transport section heating means 111 is not provided, the transport section heating means coverage ratio [%] is "0".

From the comparison between Examples 1 to 5 and Comparative Example 1, it was found that the deposition rate was dramatically improved by providing the transport section heating means 111 to heat the transport section. Further, it was found that even if the installation range of the transport section heating means 111 is a part of the transport section, the effect of improving the film forming speed can be obtained.

It should be noted that the present invention is not limited to the above embodiments. The above-described embodiment is an example, and any device having substantially the same configuration as the technical idea described in the claims of the present invention and exhibiting the same effect is the present invention. included in the technical scope of

101... Film forming apparatus, 102a... Carrier gas source,
102b... carrier gas source for dilution, 103a... flow control valve,
103b... Flow control valve, 104... Mist generation source, 104a... Raw material solution,
DESCRIPTION OF SYMBOLS 105... Container 105a... Water 106... Ultrasonic oscillator 107... Film-forming chamber,
DESCRIPTION OF SYMBOLS 108...Hot plate, 109...Transportation part, 109a...Supply pipe, 110...Base|substrate,
DESCRIPTION OF SYMBOLS 111... Transfer part heating means, 112... Exhaust port, 116... Oscillator, 117... Control part,
120... Misting section, 130... Carrier gas supply section, 140... Film forming section.

Claims (6)

A film forming apparatus,
a misting unit that mists the raw material solution to generate mist;
a carrier gas supply unit that supplies a carrier gas for transporting the mist;
a film forming unit for heat-treating the mist to form a film on a substrate;
a conveying unit that connects the misting unit and the film forming unit and conveys the mist that is supersaturated with the carrier gas;
and a transport unit heating means for heating at least a part of the transport unit. The film forming apparatus further has a control unit,
2. The film forming apparatus according to claim 1, wherein the control section controls the transfer section heating means to set the temperature of the transfer section to 30 to 120.degree. A film forming method for forming a film by heat-treating mist in a film forming unit,
a step of misting the raw material solution to generate a mist in the misting unit;
a step of heating at least part of a conveying section that connects the mist generating section and the film forming section;
a step of transporting the supersaturated mist by a carrier gas from the misting unit to the film forming unit via the transport unit;
and a step of heat-treating the mist to form a film on a substrate in the film forming unit. A film forming method for forming a film by heat-treating mist in a film forming unit,
a step of misting the raw material solution to generate a mist in the misting unit;
temperature control of at least a part of a conveying section connecting the mist generating section and the film forming section, and the supersaturated mist is transferred from the mist generating section to the film forming section via the conveying section; a step of conveying with a carrier gas;
and a step of heat-treating the mist to form a film on a substrate in the film forming unit. A film forming method for forming a film by heat-treating mist in a film forming unit,
a step of misting the raw material solution to generate a mist in the misting unit;
a step of transporting the mist from the mist generating unit to the film forming unit via the transport unit using a carrier gas; and a step of heat-treating the mist to form a film on a substrate in the film forming unit. and
The flow rate of the carrier gas and the flow rate of the mist are measured, and the amount of water vapor in the transfer section converted assuming that the mist is water vapor is compared with the saturated water vapor at room temperature to determine the temperature of at least a part of the transfer section. A film forming method, comprising a step of controlling. The film forming method according to any one of claims 3 to 5, characterized in that the temperature of the conveying section is set at 30 to 120°C.

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