JP7314016B2 - Method for forming metal oxide thin film - Google Patents

Description

The present invention relates to a method for forming a metal oxide thin film.

Thin chemically inert passivation layers such as silicon oxide (SiO) and titanium oxide (TiO) films are essential in the fabrication of semiconductor devices. For example, silicon oxide films are used for gate insulating films, sidewall spacers, and the like when forming transistors.

In recent years, semiconductor devices have been miniaturized and highly integrated, and as the horizontal and vertical dimensions of integrated circuits continue to shrink, film thickness control technology on the order of angstroms and thin film formation technology with good coverage characteristics are in demand.

A metal oxide thin film according to these requirements is produced by alternately supplying a metal precursor compound (precursor) as a source gas and an oxygen-containing compound as a reaction gas to a processing chamber. That is, it is a method in which a precursor adsorbed on the substrate surface undergoes a chemical reaction with an oxygen-containing compound by thermal energy to form a thin film. The method of forming a thin film by alternately supplying source gas and reaction gas is called atomic layer deposition (ALD).

The ALD method also includes a plasma-enhanced atomic layer deposition (PEALD) method in which the reactant gas is plasma-activated and supplied. This plasma-assisted method has the advantage of being able to lower the deposition temperature when forming a thin film, but also has the disadvantage of inevitably causing damage to the underlying substrate. In addition, it is known that the coverage characteristic by the ALD method is better than that by the chemical vapor deposition method (CVD: Chemical Vapor Deposition).

For example, as a CVD method for a silicon oxide film, monosilane (SiH ₄ ) or tetraethoxysilane (TEOS) is used as a silicon precursor, ozone (O ₃ ) or oxygen plasma (O radical) is used as an oxygen-containing compound, and a deposition temperature of 250 to 800° C. can be used. However, it is known that step coverage and deposition rate deteriorate as the deposition temperature decreases.

In particular, when a metal oxide thin film typified by a silicon oxide film is deposited on a substrate made of resin or the like, the step coverage and the film formation speed are significantly lowered due to the low heat resistance temperature of the substrate and the poor adhesion between the substrate and the deposited layer. Therefore, there is a demand for the development of a process capable of forming a high-quality metal oxide thin film at a high deposition rate without damaging the substrate.

Therefore, Japanese Patent Laid-Open No. 2002-100001 discloses a deposition method by ALD, in which the substrate temperature is heated to 550° C. or higher in order to form a good-quality silicon oxide film at a high film formation rate.

Japanese Patent No. 6262702

However, in the method for forming a silicon oxide film described in Patent Document 1, it is necessary to raise the substrate temperature, so there is a risk of destroying the device structure due to an increase in thermal budget (thermal history) and thermal stress.
Patent Document 1 also describes a process of supplying water vapor or a source of hydroxyl groups (--OH groups) at 550-750° C. for the purpose of forming reaction points in the next ALD cycle. However, when hydrogen peroxide is used as a hydroxy group supply source, self-decomposition proceeds in a temperature range exceeding 500° C., so there is a problem that the effect of forming a hydroxy (OH) terminal cannot be exhibited in the temperature range of Patent Document 1. Further, when the substrate temperature is 550° C. or higher, the substrate made of general resin cannot maintain its shape.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for forming a metal oxide thin film that is excellent in step coverage and film formation speed and capable of forming a good quality metal oxide thin film.

In order to solve the above problems, the present invention has the following configuration.
[1] Place a substrate in a processing chamber, heat the substrate in the processing chamber, and control the surface temperature of the substrate to any temperature within the range of 150° C. or higher and 500° C. or lower,
providing one or more metal precursor compounds to the substrate in the processing chamber;
supplying one or more oxygen-containing compounds to the substrate in the processing chamber;
supplying one or more hydroxyl group sources to the substrate in the processing chamber, and repeating a film formation cycle until the metal oxide thin film on the substrate reaches a desired thickness.
[2] The method for forming a metal oxide thin film according to [1] above, wherein the oxygen-containing compound and the hydroxyl group supply source are different.
[3] The method for forming a metal oxide thin film according to [1] or [2] above, wherein the steps included in the film formation cycle are performed simultaneously.
[4] The method for forming a metal oxide thin film according to [1] or [2] above, wherein the steps included in the film formation cycle are performed in this order.
[5] The method for forming a metal oxide thin film according to [4] above, wherein the film formation cycle includes a step of performing gas phase substitution in the processing chamber with an inert gas between each step.
[6] The method for forming a metal oxide thin film according to [5] above, wherein any one or a mixed gas of two or more selected from the group consisting of helium, nitrogen, and argon is used as the inert gas.
[7] The method for forming a metal oxide thin film according to any one of [1] to [6] above, wherein the pressure in the processing chamber is 13 Pa or more and 13332 Pa or less.
[8] The method for forming a metal oxide thin film according to any one of [1] to [7] above, wherein the substrate is a silicon substrate, a glass substrate, a polyimide resin substrate, or an epoxy resin substrate.
［９］ 前記金属前駆体化合物として、（ＥｔＯ） _４ Ｓｉ、（ｔＢｕＮＨ）ＳｉＨ _２ 、（ｉＰｒ _２ Ｎ）ＳｉＨ _３ （Ｍｅ _２ Ｎ） _４ Ｓｉ、（Ｍｅ _２ Ｎ） _３ ＳｉＨ、（Ｍｅ _２ Ｎ） _２ ＳｉＨ _２ 、（Ｍｅ _２ Ｎ）ＳｉＨ _３ 、（Ｅｔ _２ Ｎ） _４ Ｓｉ、（Ｅｔ _２ Ｎ） _３ ＳｉＨ、（Ｅｔ _２ Ｎ） _２ ＳｉＨ _２ 、（Ｅｔ _２ Ｎ）ＳｉＨ _３ 、（Ｍｅ _２ Ｎ） _４ Ｔｉ、ＴｉＣｌ _４ 、（Ｃ _５ Ｈ _５ ）Ｚｒ（Ｍｅ _２ Ｎ） _３ 、（ＭｅＥｔＮ） _４ Ｚｒ、ＨｆＣｌ _４ 、（ＭｅＥｔＮ） _４ Ｈｆ、（Ｍｅ _２ Ｎ） _４ Ｈｆ、Ｍｅ _３ Ａｌからなる群から選択される１種以上を供給する、前項［１］乃至［８］のいずれかに記載の金属酸化薄膜の形成方法。
[10] The method for forming a metal oxide thin film according to any one of [1] to [9] above, wherein at least one selected from the group consisting of oxygen, oxygen plasma, water vapor, water vapor plasma, hydrogen peroxide, hydrogen peroxide plasma, anhydrous hydrogen peroxide, ozone, and nitrous oxide is supplied as the oxygen-containing compound.
[11] The method for forming a metal oxide thin film according to any one of the preceding items [1] to [10], wherein at least one selected from the group consisting of hydrogen peroxide, hydrogen peroxide plasma, and anhydrous hydrogen peroxide is supplied as the hydroxyl group supply source.

The method for forming a metal oxide thin film of the present invention is excellent in step coverage and film formation speed, and can form a good quality metal oxide thin film.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a system diagram showing an example of the configuration of a film forming apparatus applicable to the method for forming a metal oxide thin film according to one embodiment of the present invention;

The configuration of a method for forming a metal oxide thin film, which is an embodiment to which the present invention is applied, will be described below in detail with reference to the drawings together with a film forming apparatus used therefor. In addition, in the drawings used in the following description, in order to make the features easier to understand, the characteristic parts may be enlarged for convenience, and the dimensional ratio of each component may not necessarily be the same as the actual one.

<Method for Forming Metal Oxide Thin Film>
The method for forming a metal oxide thin film of the present invention comprises placing a substrate in a processing chamber, heating the substrate in the processing chamber, and controlling the surface temperature of the substrate to any temperature within the range of 150° C. or more and 500° C. or less, while repeating a film formation cycle including the following steps (1) to (3) until the metal oxide thin film on the substrate reaches a desired thickness.
(1) Step of supplying one or more metal precursor compounds to the substrate in the processing chamber (2) Step of supplying one or more oxygen-containing compounds to the substrate in the processing chamber (3) Step of supplying one or more hydroxyl group supply sources to the substrate in the processing chamber

Examples of metals constituting the metal oxide thin film to be deposited in the present invention include silicon (Si), titanium (Ti), zirconia (Zr), hafnium (Hf) and aluminum (Al).
Silicon (Si) oxide films include SiO ₂ .
Titanium (Ti) oxide films include TiO, Ti ₂ O ₃ and TiO ₂ .
ZrO ₂ is an example of a zirconia (Zr) oxide film.
HfO ₂ is an example of a hafnium (Hf) oxide film.
Al ₂ O ₃ is an example of an oxide film of aluminum (Al).

The film thickness of the metal oxide thin film is not particularly limited, and is preferably selected as appropriate according to the use of the metal oxide film. The film thickness of the metal oxide thin film is preferably 1 nm or more and 10000 nm or less, more preferably 2 nm or more and 1000 nm or less, and even more preferably 5 nm or more and 100 nm or less.

Substrates applicable to the method for forming a metal oxide thin film of the present invention include silicon substrates, glass substrates, polyimide resin substrates, and epoxy resin substrates.
The heat-resistant temperature of the substrate is preferably 50° C. or higher, more preferably 100° C. or higher, and even more preferably 200° C. or higher. If the heat resistance temperature of the substrate is 200° C. or higher, deformation of the substrate due to heat during film formation can be suppressed.

The pressure in the processing chamber is preferably 13 Pa (0.1 Torr) or more and 13332 Pa (100 Torr) or less, more preferably 13 Pa or more and 6666 Pa or less, and even more preferably 13 Pa or more and 3333 Pa or less. If the pressure in the processing chamber is within the above range, the self-stopping mechanism of precursor adsorption to the substrate surface is likely to develop.

The surface temperature of the substrate in the processing chamber is preferably 150° C. or higher and 500° C. or lower, more preferably 160° C. or higher and 450° C. or lower, and even more preferably 170° C. or higher and 400° C. or lower. When the surface temperature of the substrate is 150° C. or higher, the effect of forming hydroxy (OH) terminals can be obtained. On the other hand, when the surface temperature of the substrate is 500° C. or less, the self-decomposition of the hydrogen peroxide supplied as the hydroxyl group supply source hardly progresses in the step (3) of supplying the hydroxyl group supply source, so that an excellent effect of forming hydroxy (OH) terminals can be exhibited.
Note that the higher the OH concentration on the substrate surface, the greater the amount of saturated adsorption of the precursor, which makes it possible to improve the film formation speed and film density.

In step (1) of the deposition cycle, one or more metal precursor compounds are supplied as gases to the substrate in the processing chamber.
The metal precursor compound is not particularly limited as long as it is a compound capable of forming a film at a temperature of 150°C or higher and 500°C or lower. Metal _precursor compounds include (EtO) _4Si , (tBuNH _{) SiH2} , ( _iPr2N ) _SiH3 ( _Me2N ) _4Si , ( _Me2N ) _3SiH , ( _Me2N ) _{2SiH2 ,} (Me2N) _SiH3 , ( _Et2N ) _4Si , ( _Et2N ). 3SiH, ( _Et2N ) _2SiH2 , (Et2N) _{SiH3, (Me2N)4Ti, TiCl4, (C5H5)Zr(Me2N)3 , ( MeEtN)4Zr, HfCl4, (MeEtN)4Hf , ( Me2N ) 4 Hf , Me3Al , etc. are mentioned} .
For the supply of the metal precursor compound into the processing chamber, any one selected from these groups may be supplied, or two or more may be supplied simultaneously or separately.

In step (2) of the film formation cycle, one or more oxygen-containing compounds are supplied as gas to the substrate in the processing chamber.
Oxygen-containing compounds include oxygen, oxygen plasma, water vapor, water vapor plasma, hydrogen peroxide, hydrogen peroxide plasma, anhydrous hydrogen peroxide, ozone, nitrous oxide, and the like.
The supply of the oxygen-containing compound into the processing chamber may be any one selected from these groups, or two or more thereof may be supplied simultaneously or separately.

In step (3) of the deposition cycle, one or more hydroxyl group supply sources are supplied as gas to the substrate in the processing chamber.
Hydroxyl group sources include hydrogen peroxide, hydrogen peroxide plasma, anhydrous hydrogen peroxide, and the like.
The supply of the hydroxyl group supply source into the treatment chamber may be performed by supplying any one selected from these groups, or supplying two or more of them simultaneously or separately.

The oxygen-containing compound in step (2) of the film formation cycle and the compound serving as the hydroxyl group supply source in step (3) are different.
For example, when any one of hydrogen peroxide, hydrogen peroxide plasma, and anhydrous hydrogen peroxide is used as the oxygen-containing compound in step (2), a compound other than the compound used as the oxygen-containing compound among hydrogen peroxide, hydrogen peroxide plasma, and anhydrous hydrogen peroxide is used as the compound serving as the hydroxyl group supply source in step (3).
By using different compounds for the oxygen-containing compound in the step (2) and the compound serving as the hydroxyl group supply source in the step (3), it is possible to achieve both an increase in the adsorption amount of the precursor and selection of an optimum oxidation source for the precursor.

The method for forming a metal oxide thin film of the present invention may be applied to a CVD method in which the steps (1) to (3) are performed simultaneously, or may be applied to an ALD method in which the steps (1) to (3) are performed in this order.

When the method for forming a metal oxide thin film of the present invention is applied to the ALD method, the film formation cycle including the steps (1) to (3) may include (4) the step of gas phase substitution in the processing chamber with an inert gas between steps (1) and (2) and between steps (2) and (3).
Inert gases include helium, nitrogen, argon, and the like. The supply of the inert gas into the processing chamber may be one selected from these groups, or two or more may be supplied simultaneously or separately.

In the film formation cycle, it is preferable to appropriately control the amount of gas supplied into the processing chamber by adjusting the flow rate or the like in the steps (1) to (4).
Moreover, the number of repetitions of the film formation cycle is not particularly limited, and is preferably selected appropriately according to the film formation rate and the thickness of the metal oxide thin film.

<Metal oxide thin film deposition apparatus>
Next, the configuration of a film forming apparatus applicable to the method for forming a metal oxide thin film of the present invention will be described with reference to FIG.

FIG. 1 is a system diagram showing an example of a film forming apparatus 1 applicable to the method for forming a metal oxide thin film of the present invention. As shown in FIG. 1, the film forming apparatus 1 includes a processing chamber 2 in which a substrate C is installed, and a gas introduction path L1 and a gas discharge path L2 that communicate with the processing chamber 2 . The film forming apparatus 1 can supply the raw material gas, the reaction gas, and the inert gas into the processing chamber 2 through the gas introduction path L1, and discharge the gas phase in the processing chamber 2 through the gas discharge path L2.

An opening/closing valve having a flow control function is provided in the gas introduction path L1. Further, the gas introduction path L1 branches upstream into a supply path L3 for hydrogen peroxide (H ₂ O ₂ ), a supply path L4 for oxygen (O ₂ ), a supply path L5 for nitrogen (N ₂ ), a supply path L6 for ozone (O ₃ ), and a supply path L7 for a metal precursor compound (metal precursor). The supply paths L3 to L6 are respectively provided with a mass flow meter (MFC; MassFlow Controller) and an opening/closing valve having a flow rate control function, so that the supply amount of each gas can be controlled.

If the metal precursor compound is liquid at room temperature (20° C.), the supply path L7 has a vaporizer 4 . Further, the supply route L7 branches into a route L8 that supplies the liquid extracted from the liquid phase of the container 3 in which the metal precursor compound is stored to the vaporizer 4, and a route L9 that has a heat exchanger 5 and supplies nitrogen ( _N ) as a carrier gas to the vaporizer 4. Note that the container 3 is connected to a path L10 for supplying helium (He) gas as a pressure-fed gas for the metal precursor compound. As a result, the gas obtained by vaporizing the metal precursor compound can be supplied to the substrate C in the processing chamber 2 by controlling the supply amount together with the carrier gas.

The mode of supplying the metal precursor compound is not limited to the mode described above. For example, the vapor of the metal precursor compound may be directly supplied into the processing chamber 2 from the gas phase portion of the container 3 without using the vaporizer 4 . At that time, it may be supplied together with a carrier gas.
Alternatively, the inside of the container 3 may be bubbled with a carrier gas, and the vapor of the metal precursor compound may be supplied into the processing chamber 2 together with the carrier gas.
Alternatively, the container 3 of the metal precursor compound may be appropriately heated to increase the vapor pressure and supply the metal precursor compound.

Examples of the carrier gas used when supplying the metal precursor compound include helium (He), nitrogen (N ₂ ), rare gases such as argon (Ar), and hydrogen (H ₂ ).

Moreover, the mode of supplying the oxygen-containing compound or the compound serving as the hydroxy group supply source is not limited to the mode described above. For example, when the oxygen-containing compound or the compound serving as the hydroxyl group source is liquid, the vapor of the oxygen-containing compound or the compound serving as the hydroxyl group source may be directly supplied into the processing chamber 2 from the gas phase portion in the container storing them. At that time, it may be supplied together with a carrier gas.
Alternatively, the vapor of the oxygen-containing compound or the compound serving as the hydroxyl group supply source separated using a permeable membrane may be supplied into the processing chamber 2 together with the carrier gas.
Alternatively, the inside of the vessel may be bubbled with the carrier gas, and the vapor of the oxygen-containing compound or the compound serving as the hydroxyl group supply source may be supplied into the processing chamber 2 together with the carrier gas.
Alternatively, the container of the oxygen-containing compound or the compound serving as the hydroxyl group supply source may be appropriately heated to increase the vapor pressure before supplying.

Examples of the carrier gas used for supplying the oxygen-containing compound or the compound serving as the hydroxyl group supply source include helium (He), nitrogen (N ₂ ), rare gases such as argon (Ar), and hydrogen (H ₂ ).

The gas discharge path L2 is provided with a PIA (absolute pressure gauge), an APC (automatic pressure control valve), an on-off valve having a flow control function, and a vacuum pump. The gas phase in the processing chamber 2 can be exhausted or replaced by the gas exhaust path L2.

The configuration of the film forming apparatus 1 applicable to the method for forming a metal oxide thin film of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the present invention. For example, the film forming apparatus 1 may be configured to include a remote plasma source. This makes it applicable to the PECVD method and the PEALD method.

<Evaluation method of metal oxide thin film>
The method for forming a metal oxide thin film of the present invention is excellent in film formation speed.
The deposition rate can be evaluated by calculating GPC (Growth per cycle), which is the amount of deposition per cycle, from the thickness of the obtained metal oxide film. Here, for the film thickness of the metal oxide film, for example, a value measured using a commercially available spectroscopic ellipsometer (spectroscopic ellipsometer manufactured by SOPRA: "GES5E", etc.) can be used.
In the method for forming a metal oxide thin film of the present invention, the GPC value is preferably 0.5 Å/cycle or more, more preferably 1.0 Å/cycle or more.

The thin metal oxide film obtained by the method for forming a metal oxide thin film of the present invention is excellent in step coverage.
The step coverage can be evaluated by measuring the film thickness at the top of the trench (top film thickness) and the film thickness at the bottom of the trench (bottom film thickness) of a substrate on which a trench (groove) structure with a depth of 15 μm is formed by cross-sectional observation using an electron microscope (STEM: “NX2000” manufactured by Hitachi High-Technologies Corporation, etc.), and evaluating the trench coverage obtained by the following formula (A).
Trench coverage (step coverage)=(bottom film thickness)/(top film thickness) (A)
It should be noted that the closer the value of the trench coverage obtained by the above formula (A) is to 1, the better the step coverage (step coverage). In the method for forming a metal oxide thin film of the present invention, the trench coverage value is preferably 0.8 or more, more preferably 0.9 or more.

According to the method for forming a metal oxide thin film of the present invention, a thin metal oxide film of good quality can be obtained. That is, the obtained metal oxide film has excellent film quality.
The film quality of the metal oxide film can be evaluated by the denseness of the film. Here, the denseness of the film can be determined, for example, by measuring the refractive index of the thin film using a commercially available spectroscopic ellipsometer (spectroscopic ellipsometer manufactured by SOPRA: "GES5E", etc.).

For example, when the metal oxide film is a silicon oxide film, the silicon oxide film can generally be evaluated to be of good quality when the refractive index of the thin film is within the range of 1.40 to 1.46. On the other hand, when the refractive index of the thin film is less than 1.40, it can be evaluated that the silicon oxide film has a rough film structure with many holes.

<Method for Forming Metal Oxide Thin Film by ALD>
Next, the case where the method for forming a metal oxide thin film of the present invention is applied to the ALD method will be described.

A method for forming a metal oxide thin film by the ALD method is carried out by the following steps.
A cycle including at least a step of supplying a metal precursor compound to the substrate in the processing chamber after controlling the surface temperature of the substrate in the processing chamber to a predetermined temperature, a step of purging the inside of the processing chamber with an inert gas, and a step of supplying an oxygen-containing compound to the substrate in the processing chamber to oxidize the metal precursor compound adsorbed on the substrate is defined as one cycle, and this cycle is repeated until the metal oxide thin film has a desired thickness.

Generally, it is known that it is difficult to obtain a good step coverage in the process of forming a metal oxide thin film at a low temperature. This is because the reaction progresses in a state where the thermal energy is small, so that after the supply of the oxygen-containing compound, it is difficult for the bonding state on the surface of the deposited film to become uniform, and the adsorption state of the precursor in the next cycle also becomes difficult to become uniform.

For example, in the process of forming a silicon oxide film, the anchoring functional group of the precursor compound (precursor) causes the “Si—OH” and “Si—O—Si” formed on the outermost surface of the substrate to act on the self-regulating mechanism, and chemisorption creates a starting point for the formation of a new atomic layer.

In the ALD method to which the present invention is applied, after stopping the supply of the oxygen-containing compound for the purpose of improving the step coverage in low-temperature film formation, for the purpose of promoting the formation of hydroxyl groups (OH groups) and hydrophilization on the precursor adsorption surface, a step of supplying a compound serving as a hydroxyl group supply source and a step of stopping the supply of the compound serving as a hydroxyl group supply source to the substrate in the processing chamber are performed in a plurality of steps. As a result, a large number of adsorption points of the fixed functional groups of the precursor are uniformly formed on the outermost surface of the substrate, and the step coverage and the film formation rate (film formation speed) are improved.

A specific method for forming a silicon oxide film will be described in detail below as an example of a method for forming a metal oxide thin film by the ALD method.
First, the substrate conveyed into the processing chamber is heated to a predetermined temperature.

(First step)
In a first step, a silicon precursor compound is supplied under vacuum to the substrate in the processing chamber. This causes a chemisorption reaction between the substrate surface and the silicon precursor compound.

The coexisting gas of the silicon precursor is not particularly limited, but for example, helium (He), nitrogen (N ₂ ), rare gases such as argon (Ar), and hydrogen (H ₂ ) can be used.

(Second step)
In a second step, the supply of the silicon precursor compound is stopped after the chemisorption reaction described above, and the process chamber is purged to remove any unreacted silicon precursor compound remaining therein.
Note that examples of the purge gas include inert gases such as helium (He), nitrogen (N ₂ ), and argon (Ar).

(Third step)
In the third step, an oxygen-containing compound is supplied to the substrate in the processing chamber. Thereby, the silicon precursor compound adsorbed on the substrate surface in the first step is oxidized.

Here, the oxygen-containing compound includes oxygen, oxygen plasma, water vapor, water vapor plasma, hydrogen peroxide, hydrogen peroxide plasma, anhydrous hydrogen peroxide, ozone, and nitrous oxide. At least one of these is selected and supplied.

The coexisting gas of the oxygen-containing compound is not particularly limited, but for example, inert gases such as helium (He), nitrogen ( _N ), and argon (Ar), hydrogen ( _H ), propylene, ethylene, butane, hydrocarbon gases such as acetylene, oxygen (O ₎ , and the like can be used.

(Fourth step)
In the fourth step, the supply of the oxygen-containing compound is stopped after the oxidation reaction of the silicon precursor compound described above, and a compound serving as a hydroxyl group supply source is supplied to the substrate in the processing chamber for the purpose of promoting the formation of silanol groups and hydrophilization on the outermost surface of the substrate.

Here, hydrogen peroxide, hydrogen peroxide plasma, and anhydrous hydrogen peroxide are examples of the compound that serves as a hydroxyl group supply source. At least one of these is selected and supplied. A compound different from the oxygen-containing compound described above is selected as the compound serving as the hydroxyl group supply source.

When hydrogen peroxide or anhydrous hydrogen peroxide is used as the compound serving as the hydroxyl group supply source, it is preferable to control the surface temperature of the substrate in the processing chamber to 500° C. or lower. This is because hydrogen peroxide, which has a strong hydrophilizing effect, easily undergoes a self-decomposition reaction represented by the following formula (B) in a temperature range exceeding 500°C.
2H ₂ O ₂ →2H ₂ O+O ₂ (B)

The coexisting gas of the compound serving as the hydroxyl group supply source is not particularly limited, but for example, rare gases such as helium (He), nitrogen (N ₎ , and argon (Ar), hydrogen ( _H ), propylene, ethylene, butane, hydrocarbon gases such as acetylene, and oxygen (O ₎ can be used.

When hydrogen peroxide or anhydrous hydrogen peroxide is used as the compound serving as the hydroxyl group supply source, it is preferable to use oxygen (O ₂ ) as the coexisting gas. By using oxygen as the coexisting gas, the progress of the self-decomposition reaction of hydrogen peroxide can be suppressed.

(Fifth step)
In the fifth step, after the outermost surface of the substrate is hydrophilized, the supply of the hydroxyl group source compound is stopped, and the processing chamber is purged to remove the hydroxyl group source compound remaining therein.
Note that examples of the purge gas include inert gases such as helium (He), nitrogen (N ₂ ), and argon (Ar).

The first to fifth steps described above are set as one cycle, and are repeated a plurality of times (for example, 300 cycles). Thereby, a silicon oxide film having a desired thickness can be formed on the substrate.

As described above, according to the method for forming a metal oxide thin film of the present invention, a high-quality metal oxide thin film having excellent step coverage and film formation speed can be formed.

In addition, according to the ALD method to which the method for forming a metal oxide thin film of the present invention is applied, the temperature of the substrate surface can be kept at 500° C. or less because a metal precursor compound that can form a film at a temperature of 150° C. or more and 500° C. or less is used. As a result, hydrogen peroxide can be supplied as a compound serving as a hydroxyl group supply source to form OH terminals on the surface to which the metal precursor compound is adsorbed to hydrophilize the surface (hydrophilization step). Since the decomposition of hydrogen peroxide can be suppressed, a large number of adsorption points of the precursor compound (precursor) can be uniformly formed on the outermost surface of the substrate. Therefore, it is possible to form a high-quality metal oxide thin film with excellent step coverage and film formation speed.

The technical scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention. For example, in the method for forming a silicon oxide film by the ALD method described above, in the step of supplying a silicon precursor compound, an oxygen-containing compound, and a compound serving as a hydroxyl group supply source, one type of compound is supplied, respectively. Specifically, in any one or two or more of the steps of supplying the metal precursor compound, the oxygen-containing compound, and the compound serving as the hydroxyl group supply source, two or more kinds of compounds may be mixed and supplied.

In addition, in the method of forming a silicon oxide film by the ALD method described above, in the step of supplying the silicon precursor compound, the oxygen-containing compound, and the compound serving as the hydroxy group supply source, each one type of compound is supplied in one step (one step). For example, when supplying two or more kinds of metal precursor compounds, they may be supplied in two or more multistage steps. Similarly, when supplying the oxygen-containing compound and the compound serving as the hydroxyl group supply source, they may be supplied in two or more multistage steps.

A configuration in which the total number of steps for supplying the silicon precursor compound, the oxygen-containing compound, and the compound serving as the hydroxyl group supply source is four or more will be exemplified below.

[Example 1]
(First step) Step of supplying a silicon precursor compound (Second step) Step of removing the silicon precursor remaining in the first step (Third step) Step of supplying an oxygen-containing compound (Fourth step) Step of supplying a compound serving as a hydroxyl group source (Fifth step) Step of supplying a compound serving as a hydroxyl group source different from the fourth step (Sixth step) Step of removing the compound serving as a hydroxyl group source that remained in the fifth step

[Example 2]
(First step) Step of supplying a silicon precursor compound (Second step) Step of removing a silicon precursor compound remaining in the first step (Third step) Step of supplying an oxygen-containing compound (Fourth step) Step of supplying a compound serving as a hydroxyl group source (Fifth step) Step of removing a compound serving as a hydroxyl group source remaining in the fourth step (Sixth step) Step of supplying a hafnium precursor compound (Seventh step) Step of removing a hafnium precursor compound remaining in the sixth step (Eighth step) Step of supplying an oxygen-containing compound (Ninth step) Step of supplying a compound serving as a hydroxyl group source (Tenth step) Step of removing the compound serving as a hydroxyl group source remaining in the ninth step

The effects of the present invention will be described below with reference to examples. Table 1 shows film forming conditions and evaluation results of Examples and Comparative Examples. In addition, the present invention is not limited by the following examples.

[Film Formation Example 1: Atomic Layer Deposition of Silicon Oxide Film]
Using the film forming apparatus 1 shown in FIG. 1, a silicon oxide film was formed by ALD on a substrate having a trench (groove) structure with a depth of 15 μm.
The silicon oxide film was evaluated by spectroscopic ellipsometry and cross-sectional observation. In spectroscopic ellipsometry, film thickness and refractive index were measured, and GPC (Growth per cycle) was calculated as the amount of film formed per cycle from the obtained film thickness. In addition, by observing the cross section of the trench structure portion, the film thicknesses of the upper portion and the bottom portion of the trench were measured to evaluate the step coverage (step coverage).

<Comparative Example 1-1>
The details of the film formation conditions, film formation cycles, and evaluation results are as follows.
(Deposition conditions)
・Substrate: Silicon substrate ・Deposition temperature (substrate surface temperature): 250°C
・Metal precursor compound: trisdimethylaminosilane (3DMAS)
・Oxygen-containing compound: ozone (O ₃ )
- A compound that serves as a hydroxyl group (OH group) supply source: none - The number of repetitions of the following film formation cycle: 300 times (film formation cycle)
First step: 3DMAS is supplied into the processing chamber and adhered to the substrate surface for 5 seconds.
Second step: Purge with _N2 for 10 seconds to remove unreacted 3DMAS.
Third step: O ₃ is supplied into the processing chamber to oxidize the substrate surface on which 3DMAS is adsorbed for 10 seconds.
Fourth step: Purge with _N2 for 10 seconds to remove unreacted _O3 .
(Evaluation results)
・GPC: 0.65 (Å/cycle)
・Refractive index: 1.42
・Step coverage: 0.81

<Comparative Example 1-2>
The details of the film formation conditions, film formation cycles, and evaluation results are as follows.
(Deposition conditions)
・Substrate: Silicon substrate ・Deposition temperature (substrate surface temperature): 250°C
・Metal precursor compound: trisdimethylaminosilane (3DMAS)
・Oxygen-containing compound: ozone (O ₃ )
- A compound that serves as a hydroxyl group (OH group) supply source: water vapor (H ₂ O)
・The number of repetitions of the following film formation cycle: 300 times (film formation cycle)
First step: 3DMAS is supplied into the processing chamber and adhered to the substrate surface for 5 seconds.
Second step: Purge with _N2 for 10 seconds to remove unreacted 3DMAS.
Third step: O3 is supplied into the processing chamber to oxidize the substrate surface on which 3DMAS is adsorbed for 10 seconds.
Fourth step: H ₂ O is supplied into the processing chamber to hydrophilize the substrate surface for 10 seconds.
Fifth step: Purge with _N2 for 10 seconds to remove unreacted _H2O .
(Evaluation results)
・GPC: 0.64 (Å/cycle)
・Refractive index: 1.42
・Step coverage: 0.81

When water vapor was used as the compound serving as the hydroxyl group (OH group) supply source, the GPC and step coverage did not change as compared with Comparative Example 1-1 in which the step of supplying the OH group supply source was not performed. Therefore, it was shown that the hydrophilization process using water vapor has little effect on improving the film forming speed and step coverage.

<Comparative Example 1-3>
The details of the film formation conditions, film formation cycles, and evaluation results are as follows.
(Deposition conditions)
・Substrate: Silicon substrate ・Deposition temperature (substrate surface temperature): 550°C
・Metal precursor compound: trisdimethylaminosilane (3DMAS)
・Oxygen-containing compound: ozone (O ₃ )
- A compound that serves as a hydroxyl group (OH group) supply source: none - The number of repetitions of the following film formation cycle: 300 times (film formation cycle)
First step: 3DMAS is supplied into the processing chamber and adhered to the substrate surface for 5 seconds.
Second step: Purge with _N2 for 10 seconds to remove unreacted 3DMAS.
Third step: O ₃ is supplied into the processing chamber to oxidize the substrate surface on which 3DMAS is adsorbed for 10 seconds.
Fourth step: Purge with _N2 for 10 seconds to remove unreacted _O3 .
(Evaluation results)
・GPC: 0.91 (Å/cycle)
・Refractive index: 1.43
・Step coverage: 0.82

<Comparative Example 1-4>
The details of the film formation conditions, film formation cycles, and evaluation results are as follows.
(Deposition conditions)
・Substrate: Silicon substrate ・Deposition temperature (substrate surface temperature): 550°C
・Metal precursor compound: trisdimethylaminosilane (3DMAS)
・Oxygen-containing compound: ozone (O ₃ )
- A compound that serves as a hydroxyl group (OH group) supply source: hydrogen peroxide (H ₂ O ₂ )
・The number of repetitions of the following film formation cycle: 300 times (film formation cycle)
First step: 3DMAS is supplied into the processing chamber and adhered to the substrate surface for 5 seconds.
Second step: Purge with _N2 for 10 seconds to remove unreacted 3DMAS.
Third step: O ₃ is supplied into the processing chamber to oxidize the substrate surface on which 3DMAS is adsorbed for 10 seconds.
Fourth step: H ₂ O ₂ is supplied into the processing chamber to hydrophilize the substrate surface for 10 seconds.
Fifth step: Purge with _N2 for 10 seconds to remove _{unreacted H2O2} .
(Evaluation results)
・GPC: 0.90 (Å/cycle)
・Refractive index: 1.43
・Step coverage: 0.82

When hydrogen peroxide was supplied as a compound serving as a hydroxyl group (OH group) supply source under the condition that the surface temperature of the substrate was 550° C., GPC and step coverage did not change as compared with Comparative Example 1-3 in which there was no step of supplying a hydroxyl group (OH group) supply source. Therefore, it was shown that under the heating condition of the substrate temperature of 550° C., the self-decomposing property of hydrogen peroxide has little effect on improving the film forming speed and step coverage in the hydrophilization step.

<Example 1-1>
The details of the film formation conditions, film formation cycles, and evaluation results are as follows.
(Deposition conditions)
・Substrate: Silicon substrate ・Deposition temperature (substrate surface temperature): 250°C
・Metal precursor compound: trisdimethylaminosilane (3DMAS)
・Oxygen-containing compound: ozone (O ₃ )
- A compound that serves as a hydroxyl group (OH group) supply source: hydrogen peroxide (H ₂ O ₂ )
・The number of repetitions of the following film formation cycle: 300 times (film formation cycle)
First step: 3DMAS is supplied into the processing chamber and adhered to the substrate surface for 5 seconds.
Second step: Purge with _N2 for 10 seconds to remove unreacted 3DMAS.
Third step: O ₃ is supplied into the processing chamber to oxidize the substrate surface on which 3DMAS is adsorbed for 10 seconds.
Fourth step: H ₂ O ₂ is supplied into the processing chamber to hydrophilize the substrate surface for 10 seconds.
Fifth step: Purge with _N2 for 10 seconds to remove _{unreacted H2O2} .
(Evaluation results)
・GPC: 0.71 (Å/cycle)
・Refractive index: 1.42
・Step coverage: 0.89

When hydrogen peroxide was supplied as a compound serving as a hydroxyl group (OH group) supply source under the condition that the surface temperature of the substrate was 250° C., GPC and step coverage were improved as compared with Comparative Example 1-1 in which there was no step of supplying a hydroxyl group (OH group) supply source. Therefore, it was shown that the heating condition of the substrate temperature of 250° C. is effective for improving the film formation rate and step coverage in the hydrophilization process.

<Example 1-2>
The details of the film formation conditions, film formation cycles, and evaluation results are as follows.
(Deposition conditions)
・Substrate: Silicon substrate ・Deposition temperature (substrate surface temperature): 250°C
・Metal precursor compound: trisdimethylaminosilane (3DMAS)
・Oxygen-containing compound: ozone (O ₃ )
- A compound that serves as a hydroxyl group (OH group) supply source: _anhydrous hydrogen peroxide ( _H2O2 )
・The number of repetitions of the following film formation cycle: 300 times (film formation cycle)
First step: 3DMAS is supplied into the processing chamber and adhered to the substrate surface for 5 seconds.
Second step: Purge with _N2 for 10 seconds to remove unreacted 3DMAS.
Third step: O ₃ is supplied into the processing chamber to oxidize the substrate surface on which 3DMAS is adsorbed for 10 seconds.
Fourth step: Anhydrous H ₂ O ₂ is supplied into the processing chamber to hydrophilize the substrate surface for 10 seconds.
Fifth step: Purge with _N2 for 10 seconds to remove unreacted _{anhydrous H2O2} .
(Evaluation results)
・GPC: 0.74 (Å/cycle)
・Refractive index: 1.43
・Step coverage: 0.93

When anhydrous hydrogen peroxide was supplied as a compound serving as a hydroxy group (OH group) supply source under the condition that the surface temperature of the substrate was 250° C., GPC and step coverage were improved compared to Comparative Example 1-1, which did not include the step of supplying a hydroxy group (OH group) supply source, and Example 1-1 using hydrogen peroxide. Therefore, under the heating condition of the substrate temperature of 250° C., anhydrous hydrogen peroxide was shown to be more effective than hydrogen peroxide in improving the film formation rate and step coverage.

[Film Formation Example 2: Atomic Layer Deposition of Titanium Oxide Film]
Using the film forming apparatus 1 shown in FIG. 1, a titanium oxide film was formed by ALD on a substrate having a trench (groove) structure with a depth of 15 μm.
The titanium oxide film was evaluated by spectroscopic ellipsometry and cross-sectional observation. In spectroscopic ellipsometry, film thickness and refractive index were measured, and GPC (Growth per cycle) was calculated as the amount of film formed per cycle from the obtained film thickness. In addition, by observing the cross section of the trench structure portion, the film thicknesses of the upper portion and the bottom portion of the trench were measured to evaluate the step coverage (step coverage).

<Comparative Example 2-1>
The details of the film formation conditions, film formation cycles, and evaluation results are as follows.
(Deposition conditions)
・Substrate: Silicon substrate ・Deposition temperature (substrate surface temperature): 180°C
・Metal precursor compound: tetrakisdimethylaminotitanium (TDMAT)
・Oxygen-containing compound: ozone (O ₃ )
- A compound that serves as a hydroxyl group (OH group) supply source: none - The number of repetitions of the following film formation cycle: 300 times (film formation cycle)
First step: TDMAT is supplied into the processing chamber and adsorbed on the substrate surface for 5 seconds.
Second step: Purge with _N2 for 10 seconds to remove unreacted TDMAT.
Third step: O ₃ is supplied into the processing chamber to oxidize the surface of the substrate on which TDMAT is adsorbed for 10 seconds.
Fourth step: Purge with _N2 for 10 seconds to remove unreacted _O3 .
(Evaluation results)
・GPC: 0.95 (Å/cycle)
・Refractive index: 2.49
・Step coverage: 0.93

<Comparative Example 2-2>
The details of the film formation conditions, film formation cycles, and evaluation results are as follows.
(Deposition conditions)
・Substrate: polyimide substrate ・Deposition temperature (substrate surface temperature): 180°C
・Metal precursor compound: tetrakisdimethylaminotitanium (TDMAT)
・Oxygen-containing compound: ozone (O ₃ )
- A compound that serves as a hydroxyl group (OH group) supply source: none - The number of repetitions of the following film formation cycle: 300 times (film formation cycle)
First step: TDMAT is supplied into the processing chamber and adsorbed on the substrate surface for 5 seconds.
Second step: Purge with _N2 for 10 seconds to remove unreacted TDMAT.
Third step: O ₃ is supplied into the processing chamber to oxidize the surface of the substrate on which TDMAT is adsorbed for 10 seconds.
Fourth step: Purge with _N2 for 10 seconds to remove unreacted _O3 .
[Evaluation results]
・GPC: 0.77 (Å/cycle)
・Refractive index: 2.47
・Step coverage: 0.82

<Example 2-1>
The details of the film formation conditions, film formation cycles, and evaluation results are as follows.
(Deposition conditions)
・Substrate: Silicon substrate ・Deposition temperature (substrate surface temperature): 180°C
・Metal precursor compound: tetrakisdimethylaminotitanium (TDMAT)
・Oxygen-containing compound: ozone (O ₃ )
- A compound that serves as a hydroxyl group (OH group) supply source: _anhydrous hydrogen peroxide ( _H2O2 )
・The number of repetitions of the following film formation cycle: 300 times (film formation cycle)
First step: TDMAT is supplied into the processing chamber and adsorbed on the substrate surface for 5 seconds.
Second step: Purge with _N2 for 10 seconds to remove unreacted TDMAT.
Third step: O ₃ is supplied into the processing chamber to oxidize the surface of the substrate on which TDMAT is adsorbed for 10 seconds.
Fourth step: Anhydrous H ₂ O ₂ is supplied into the processing chamber to hydrophilize the substrate surface for 10 seconds.
Fifth step: Purge with _N2 for 10 seconds to remove unreacted _{anhydrous H2O2} .
(Evaluation results)
・GPC: 1.02 (Å/cycle)
・Refractive index: 2.49
・Step coverage: 0.95

When anhydrous hydrogen peroxide was supplied as a compound serving as a hydroxy group (OH group) supply source under the condition that the surface temperature of the substrate was 180° C., GPC and step coverage were improved as compared with Comparative Example 2-1 in which there was no step of supplying a hydroxy group (OH group) supply source. Therefore, in the formation process of the titanium oxide film, it was shown that the hydrophilization step with anhydrous hydrogen peroxide is effective for improving the film forming speed and step coverage under the heating condition of the substrate temperature of 180°C.

<Example 2-2>
The details of the film formation conditions, film formation cycles, and evaluation results are as follows.
(Deposition conditions)
・Substrate: polyimide substrate ・Deposition temperature (substrate surface temperature): 180°C
・Metal precursor compound: tetrakisdimethylaminotitanium (TDMAT)
・Oxygen-containing compound: ozone (O ₃ )
- A compound that serves as a hydroxyl group (OH group) supply source: _anhydrous hydrogen peroxide ( _H2O2 )
・The number of repetitions of the following film formation cycle: 300 times (film formation cycle)
First step: TDMAT is supplied into the processing chamber and adsorbed on the substrate surface for 5 seconds.
Second step: Purge with _N2 for 10 seconds to remove unreacted TDMAT.
Third step: O ₃ is supplied into the processing chamber to oxidize the surface of the substrate on which TDMAT is adsorbed for 10 seconds.
Fourth step: Anhydrous H ₂ O ₂ is supplied into the processing chamber to hydrophilize the substrate surface for 10 seconds.
Fifth step: Purge with _N2 for 10 seconds to remove unreacted _{anhydrous H2O2} .
(Evaluation results)
・GPC: 0.94 (Å/cycle)
・Refractive index: 2.49
・Step coverage: 0.92

When anhydrous hydrogen peroxide was used as the compound serving as the hydroxyl group (OH group) supply source under the condition that the surface temperature of the substrate was 180° C., GPC and step coverage were improved as compared with Comparative Example 2-2 in which there was no supply step of the hydroxyl group (OH group) supply source. Therefore, in the formation process of the titanium oxide film, it was shown that the hydrophilization step with anhydrous hydrogen peroxide is effective for improving the film forming speed and step coverage under the heating condition of the substrate temperature of 180°C.

[Film Formation Example 3: Atomic Layer Deposition of Aluminum Oxide Film]
An aluminum oxide film was formed by the PEALD method on a substrate in which a trench (groove) structure with a depth of 15 μm was formed, using a film forming apparatus equipped with a remote plasma source in the film forming apparatus 1 shown in FIG.
Evaluation of the aluminum oxide film was performed by spectroscopic ellipsometry and cross-sectional observation. In spectroscopic ellipsometry, film thickness and refractive index were measured, and GPC (Growth per cycle) was calculated as the amount of film formed per cycle from the obtained film thickness. In addition, by observing the cross section of the trench structure portion, the film thicknesses of the upper portion and the bottom portion of the trench were measured to evaluate the step coverage (step coverage).

<Comparative Example 3-1>
The details of the film formation conditions, film formation cycles, and evaluation results are as follows.
(Deposition conditions)
・Substrate: Silicon substrate ・Deposition temperature (substrate surface temperature): 200°C
・Metal precursor compound: trimethylaluminum (TMA)
Oxygen-containing compounds: oxygen plasma ( _O2 plasma)
- A compound that serves as a hydroxyl group (OH group) supply source: none - The number of repetitions of the following film formation cycle: 300 times (film formation cycle)
First step: TMA is supplied into the processing chamber and adhered to the substrate surface for 5 seconds.
Second step: Purge with _N2 for 10 seconds to remove unreacted TMA.
Third step: O ₂ plasma is supplied into the processing chamber to oxidize the substrate surface on which TMA is adsorbed for 10 seconds.
Fourth step: Purge with _N2 for 10 seconds to remove unreacted _O2 plasma.
(Evaluation results)
・GPC: 1.07 (Å/cycle)
・Refractive index: 1.66
・Step coverage: 0.85

<Comparative Example 3-2>
The details of the film formation conditions, film formation cycles, and evaluation results are as follows.
(Deposition conditions)
・Substrate: Silicon substrate ・Deposition temperature (substrate surface temperature): 200°C
・Metal precursor compound: trimethylaluminum (TMA)
- Oxygen-containing compound: Water vapor ( _H2O )
- A compound that serves as a hydroxyl group (OH group) supply source: none - The number of repetitions of the following film formation cycle: 300 times (film formation cycle)
First step: TMA is supplied into the processing chamber and adhered to the substrate surface for 5 seconds.
Second step: Purge with _N2 for 10 seconds to remove unreacted TMA.
Third step: H ₂ O is supplied into the processing chamber to oxidize the surface of the substrate on which TMA is adsorbed for 10 seconds.
Fourth step: Purge with _N2 for 10 seconds to remove unreacted _H2O .
(Evaluation results)
・GPC: 0.93 (Å/cycle)
・Refractive index: 1.65
・Step coverage: 0.91

When water vapor was used as the oxygen-containing compound under the condition that the surface temperature of the substrate was 200° C., the GPC was lower than in Comparative Example 3-1 using oxygen plasma as the oxygen-containing compound, but the step coverage was improved.

<Example 3-1>
The details of the film formation conditions, film formation cycles, and evaluation results are as follows.
(Deposition conditions)
・Substrate: Silicon substrate ・Deposition temperature (substrate surface temperature): 200°C
・Metal precursor compound: trimethylaluminum (TMA)
- Oxygen-containing compound: Water vapor ( _H2O )
- A compound that serves as a hydroxyl group (OH group) supply source: _anhydrous hydrogen peroxide ( _H2O2 )
・The number of repetitions of the following film formation cycle: 300 times (film formation cycle)
First step: TMA is supplied into the processing chamber and adhered to the substrate surface for 5 seconds.
Second step: Purge with _N2 for 10 seconds to remove unreacted TMA.
Third step: H ₂ O is supplied into the processing chamber to oxidize the surface of the substrate on which TMA is adsorbed for 10 seconds.
Fourth step: Anhydrous H ₂ O ₂ is supplied into the processing chamber to hydrophilize the substrate surface for 10 seconds.
Fifth step: Purge with _N2 for 10 seconds to remove unreacted _{anhydrous H2O2} .
(Evaluation results)
・GPC: 1.03 (Å/cycle)
・Refractive index: 1.66
・Step coverage: 0.93

When anhydrous hydrogen peroxide was used as a compound serving as a hydroxyl group (OH group) supply source under the condition that the surface temperature of the substrate was 200° C., GPC and step coverage were improved as compared with Comparative Examples 3-1 and 3-2. Therefore, in the process of forming an aluminum oxide film, it was shown that the hydrophilization step using anhydrous hydrogen peroxide is effective for improving the film formation rate and step coverage under the heating condition of the substrate temperature of 200°C.
Examples 1-1, 1-2, 2-1, 2-2, and 3-1 are reference examples.

The method for forming a metal oxide thin film of the present invention has industrial applicability to a method for forming a thin metal oxide film using an atomic layer deposition (ALD) method in which the surface temperature of the substrate is controlled to 150°C to 500°C.

DESCRIPTION OF SYMBOLS 1... Film-forming apparatus 2... Processing chamber 3... Container 4... Vaporizer 5... Heat exchanger C... Substrate L1-L10... Path|route

Claims (7)

A substrate is placed in a processing chamber, and the substrate in the processing chamber is heated to control the surface temperature of the substrate to any temperature within the range of 150° C. or more and 500° C. or less,
providing one or more metal precursor compounds to the substrate in the processing chamber;
supplying one or more oxygen-containing compounds to the substrate in the processing chamber;
providing one or more hydroxyl group sources to the substrate in the processing chamber ;
The step of supplying the metal precursor compound, the step of supplying the oxygen-containing compound, and the step of supplying the hydroxy group supply source are performed in this order,
the hydroxy group source comprises hydrogen peroxide or anhydrous hydrogen peroxide;
The oxygen-containing compound does not contain hydrogen peroxide or anhydrous hydrogen peroxide supplied in the step of supplying the hydroxy group supply source,
A method for forming a metal oxide thin film , wherein the coexisting gas of the hydroxyl group supply source is oxygen, and a film forming cycle is repeated until the metal oxide thin film on the substrate reaches a desired thickness. 2. The method of forming a metal oxide thin film according to claim 1 , wherein said film forming cycle includes a step of performing vapor phase replacement in said processing chamber with an inert gas between each step. 3. The method of forming a metal oxide thin film according to claim 2 , wherein any one or a mixed gas of two or more selected from the group consisting of helium, nitrogen and argon is used as the inert gas. 4. The method for forming a metal oxide thin film according to claim 1, wherein the pressure in said processing chamber is 13 Pa or more and 13332 Pa or less. 5. The method of forming a metal oxide thin film according to claim 1 , wherein said substrate is a silicon substrate, a glass substrate, a polyimide resin substrate, or an epoxy resin substrate. As the metal precursor compound, (EtO)₄Si, (tBuNH) ₂ SiH₂, (iPr₂N) SiH₃, (Me₂N)₄Si, (Me₂N)₃SiH, (Me₂N)₂SiH₂, (Me₂N) SiH₃ ,(Et₂N)₄Si, (Et₂N)₃SiH, (Et₂N)₂SiH₂, (Et₂N) SiH₃, (Me₂N)₄Ti, TiCl₄, (C₅H.₅) Zr(Me₂N)₃, (MeEtN)₄Zr, HfCl₄, (MeEtN)₄Hf, (Me₂N)₄Hf, Me₃Supplying one or more selected from the group consisting of Al, claims 1 to5The method for forming a metal oxide thin film according to any one of . The method for forming a metal oxide thin film according to any one of claims 1 to 6 , wherein one or more selected from the group consisting of oxygen, oxygen plasma, water vapor, water vapor plasma, hydrogen peroxide, hydrogen peroxide plasma, anhydrous hydrogen peroxide, ozone, and nitrous oxide is supplied as the oxygen-containing compound.

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