TW201800605A - Method of manufacturing aluminum oxide film and raw material for manufacturing aluminum oxide film - Google Patents

Abstract

Provided is a method of manufacturing aluminum oxide film that forms an aluminum oxide film by supplying an aluminum compound with specific structure onto a film formation target heated to 300~550 DEG C and oxidizing the aluminum compound.

Description

Method for manufacturing alumina film and raw material for manufacturing alumina film

The present invention relates to a method for producing an alumina film on a film-forming object and a raw material for producing the alumina film.

In the past, alumina films have been known as useful films such as gate insulating films, and have been widely used in the semiconductor field. Therefore, in recent years, higher-quality alumina films have been sought. For this reason, some people are researching suitable aluminum compounds (raw materials for manufacturing alumina films) for producing high-quality alumina films (for example, refer to Patent Documents 1 to 3 and Non-Patent Document 3).

In addition, Patent Document 4 discloses an alkyl aluminum dihalide compound as a polymerization catalyst. Non-Patent Literature 1 and Non-Patent Literature 2 disclose measurement examples or synthesis examples of alkyl dihalide compounds. [Prior Art Literature] [Patent Literature]

[Patent Literature 1] WO2004 / 108985 [Patent Literature 2] Japanese Patent No. 4716193 [Patent Literature 3] Japanese Patent Laid-Open No. 2007-138296 [Patent Literature 4] WO2015 / 164972 [Non-Patent Literature]

[Non-Patent Document 1] Chemische. Berichte, 102, 1937-1943 (1969) [Non-Patent Document 2] Journal Of Organometallic Chemistry, 76, 171-201 (1974) [Non-Patent Document 3] Inorganic Materials, Vol. 38, No. 5, 2002, 438-444.

[Problems to be Solved by the Invention] Non-Patent Document 1, Non-Patent Document 2 and Patent Document 4 do not describe the gist of the usefulness of an alkyldihalide compound as a raw material for producing an alumina film. In addition, although Non-Patent Document 3 describes a method for producing an aluminum oxide film by a chemical vapor deposition method (hereinafter referred to as a "CVD method"), it does not describe other film formation methods. Study of method or film forming temperature.

In addition, as described in Patent Document 1, it is known that a general alkyl dihalide compound has self-ignitability and is difficult to handle, so it is not ideal as a raw material for producing an alumina film. Further, if impurities such as aluminum chloride and aluminum carbide are mixed during film formation, the use in semiconductors and the like is not ideal. Therefore, the obtained alumina film needs to be chemically high in purity. Further, for applications such as semiconductors, the thickness of the aluminum oxide film needs to be uniform.

Therefore, the main subject of the present invention is to produce a high-quality alumina film by an industrially appropriate method, and to provide a raw material for producing the alumina film. [Means for solving problems]

As a result of repeated research by the inventors of this case, it was found that an alkyl aluminum halide compound having a specific structure is non-self-ignitable, and is an alumina film manufacturing material capable of manufacturing high-quality alumina films without halogen atoms. invention.

Among them, in the present invention, high quality means that the purity in terms of chemistry is high, and the thickness of the obtained alumina film is uniform within the same film.

The method for producing an alumina film of the present invention is to supply an aluminum compound represented by the following general formula (1) to a film-forming object that has been heated to 300 to 550 ° C, and oxidize it to form an alumina film.

式中，R表示碳原子數1~6之直鏈狀之烷基，X表示鹵素基，2個X可相同或不同。[Chemical 1]

In the formula, R represents a linear alkyl group having 1 to 6 carbon atoms, X represents a halogen group, and two X's may be the same or different.

The raw material for producing the alumina film of the present invention is composed of an aluminum compound represented by the following general formula (1).

式中，R表示碳原子數1~6之直鏈狀之烷基，X表示鹵素基，2個X可相同或不同。 [發明之效果][Chemical 2]

In the formula, R represents a linear alkyl group having 1 to 6 carbon atoms, X represents a halogen group, and two X's may be the same or different. [Effect of the invention]

According to the present invention, it is possible to provide an alumina film manufacturing method capable of manufacturing a high-quality alumina film and raw materials for manufacturing the alumina film.

The method for producing an alumina film of the present invention is characterized in that an aluminum compound represented by the following general formula (1) is supplied to a film-forming object heated to 300 ° C. to 550 ° C. and is oxidized to form an alumina film.

式中，R表示碳原子數1~6之直鏈狀之烷基，X表示鹵素基，2個X可相同或不同。[Chemical 3]

In the formula, R represents a linear alkyl group having 1 to 6 carbon atoms, X represents a halogen group, and two X's may be the same or different.

(Aluminum compound) The aluminum compound used in the method for producing an aluminum oxide film according to the present invention is an alkyl aluminum dihalide compound represented by the general formula (1).

The R-based linear alkyl group having 1 to 6 carbon atoms in the general formula (1) is preferably a linear alkyl group having 1 to 3 carbon atoms. Examples of R include methyl, ethyl, n-propyl, n-butyl, n-pentyl, and n-hexyl. Among them, methyl and ethyl are preferred, and ethyl is particularly preferred. Among them, n-propyl represents a straight-chain propyl, and other alkyl groups are the same.

X is a halogen group in the general formula (1). Examples include chloro, bromo, and iodo. Among them, a chloro group is preferred. Although two X in the general formula (1) may be the same or different, they are preferably the same.

Specific preferable examples of the aluminum compound used in the method for producing an alumina film of the present invention include compounds represented by the following formulae (2) to (7). Among them, compounds represented by the following formulae (2) and (3) are preferably used, and compounds represented by the following formula (3) are more preferably used.

[Chemical 4]

In the formula, Me, Et, ⁿ Pr, ⁿ Bu, ⁿ Pen, and ⁿ Hex each represent methyl, ethyl, n-propyl, n-butyl, n-pentyl, or n-hexyl.

The above-mentioned aluminum compound is used as a raw material for the production of an alumina film, and the above-mentioned aluminum compound is preferably used as a raw material for the production of an alumina film using an atomic layer deposition (Atomic Layer Deposition; hereinafter referred to as "ALD method").

As the film formation method, a general ALD method or a CVD method can be cited, but the ALD method is preferable from the viewpoint that it is easy to control the film thickness, has good step film properties, and can form a uniform and dense film. However, as described in the second paragraph of Chem. Mater. 2010, 22, 4844-4853, p. Of materials. However, the aluminum compound can be formed into a film even if it is an ALD method.

(Film Forming Object) As the film forming object, for example, SiO ₂ / Si, Si, TiN / Si, ZrO ₂ / Si, Si ₃ N ₄ / SiO ₂ / Si, etc., and is preferably SiO ₂ / Si. .

(Production method of alkyl dihalide compound [aluminum compound represented by the above-mentioned general formula (1)]) The alkyl dihalide compound used in the method for producing an alumina film of the present invention can be obtained by, for example, combining aluminum trihalide with Trialkyl aluminum is produced by a reaction method.

As for the aluminum trihalide, for example, aluminum trichloride, aluminum tribromide, aluminum triiodide, etc. may be mentioned, and aluminum trichloride is preferred.

As the trialkyl aluminum, for example, trimethylaluminum, triethylaluminum, tripropylaluminum, tributylaluminum, trihexylaluminum, etc., and trimethylaluminum, triethylaluminum, The propyl aluminum and tributyl aluminum are more preferably trimethyl aluminum, triethyl aluminum, and further preferably triethyl aluminum.

Relative to 1 mol of aluminum trihalide, the use amount of the above trialkylaluminum is preferably 0.1 to 1.0 mol, more preferably 0.2 to 0.7 mol, and still more preferably 0.2 to 0.5 mol.

The above reaction is desirably performed in an organic solvent, and the organic solvent used is not particularly limited as long as it does not hinder the reaction. Examples include aliphatic hydrocarbons such as hexane, heptane, cyclohexane, methylcyclohexane, and ethylcyclohexane; aromatic hydrocarbons such as toluene and xylene; ether, tetrahydrofuran, and dimethoxyethane ,two Dioxane and other ethers are preferably a mixed solvent of aliphatic hydrocarbons and aromatic hydrocarbons, or aliphatic hydrocarbons. Among them, these organic solvents may be used singly or in combination of two or more kinds.

Relative to 1 g of aluminum trihalide, the amount of the organic solvent used is preferably 1 g to 100 g, more preferably 3 g to 50 g, and still more preferably 3 g to 10 g.

(Synthesis method) The above reaction is carried out by a method such as mixing an aluminum trihalide, a trialkyl aluminum, and an organic solvent to perform a reaction. At this time, the reaction temperature is preferably -100 ° C to 100 ° C, more preferably -80 ° C to 40 ° C, and the reaction pressure is not particularly limited.

The alkyl aluminum dihalide compound obtained as the target product through the above reaction can be separated and purified by conventional methods such as extraction, filtration, concentration, distillation, sublimation, recrystallization, column chromatography and the like after the reaction is completed. Alkyl dihalide compounds.

Among them, the alkyl dihalide compound and the aluminum trihalide compound and the trialkyl aluminum compound which are raw materials for its manufacture are often unstable to moisture or oxygen in the air, and it is desirable to perform the above under anhydrous conditions or inert gas conditions. Reaction operation of the reaction or subsequent treatment of the reaction solution.

The alkyl dihalide compound is suitably used as a raw material (raw material for manufacturing) for manufacturing an alumina film. It is preferable that the manufacturing raw material (raw material for manufacturing) for manufacturing an alumina film is composed only of an alkyl dihalide compound. However, the above-mentioned manufacturing raw materials (raw materials for manufacturing) may contain a small amount of impurities (aluminum compounds, etc.) other than the alkyl dihalide compound within a range that does not significantly affect the quality of the formed alumina film.

(Film-forming method) As an evaporation method of an alumina film on a film-forming object, for example, an ALD method or a CVD method can be mentioned, and an ALD method is preferably used.

Specifically, for example, under normal pressure or reduced pressure, the vapor of the alkyldihalide compound can be supplied together with the reactive gas to the heated film-forming object, and the alkyldihalide compound can be oxidized to An aluminum oxide film is formed. Among them, a gas containing a vapor of an alkyl aluminum dihalide compound (including a gasified liquid) can be diluted with an inert gas or the like. In addition, by supplying raw materials in the same manner, an aluminum oxide film can also be deposited by plasma CVD.

As for the reactive gas, oxidizing gases such as oxygen and ozone can be listed; water; alcohols such as methanol, ethanol, n-propanol, isopropanol, and n-butanol can be formed into high-quality alumina by ALD The viewpoint of the membrane is preferably water and ozone, and more preferably water. The alkyl dihalide compound is oxidized by the above-mentioned reactive gas. In this way, alumina is vapor-deposited on the film-forming object to form an alumina film. These reactive gases may be used singly or in combination. Examples of the inert gas include argon, nitrogen, and helium.

In the CVD method, in order to form a thin film, it is necessary to vaporize an alkyl aluminum dihalide compound. As a method for vaporizing an alkyl aluminum dihalide compound, for example, not only a method for filling or transporting an alkyl aluminum dihalide compound to a gasification chamber for vaporization, but also diluting an alkyl aluminum dihalide compound In appropriate solvents (such as hexane, cyclohexane, methylcyclohexane, ethylcyclohexane, heptane, octane and other aliphatic hydrocarbons; toluene, ethylbenzene, xylene and other aromatic hydrocarbons ; Ether, tetrahydrofuran, dimethoxyethane, di Ethers such as dioxane. ) The solution obtained by introducing the solution into a gasification chamber by a liquid transfer pump (solution method).

The pressure in the reaction system when an aluminum dihalide compound is used to vaporize an aluminum oxide film should preferably be 1 Pa to 200 kPa, and more preferably 10 Pa to 110 kPa. The temperature of the film-forming object when the aluminum dihalide compound is used to evaporate the aluminum oxide film is preferably 250 ° C to 580 ° C, more preferably 300 ° C to 550 ° C, further preferably 480 ° C to 550 ° C, and particularly preferably 500. ~ 550 ° C. In addition, in terms of aspects, for example, from the viewpoint of low-temperature synthesis or reduction of film thickness, it is preferably 250 ° C to 600 ° C, more preferably 300 ° C to 500 ° C, and still more preferably 300 ° C to 350 ° C. The temperature at which the alkyl aluminum dihalide compound is gasified is preferably 30 ° C to 250 ° C, and more preferably 60 ° C to 200 ° C.

Among them, the content ratio of the oxygen source (such as oxidizing gas, water vapor or alcohol vapor, or a mixed gas thereof) should be 3 to 99% by volume relative to the total gas amount when the alumina film is evaporated. It should be 5 ~ 98% by volume.

The film forming method of the present invention is an industrially suitable method to obtain a high-quality alumina compound.

In addition, in J. Am. Chem. Soc., 1989, 111 (5), 1634-1644, it is described that the butyl on aluminum is decomposed due to the release of β hydrogen atoms, and there is no aluminum film formed by oxidation, but by using an alkane The aluminum dihalide compound is formed into a film by the above-mentioned film forming method to obtain a high-quality alumina film.

The aluminum oxide film of this embodiment is formed by supplying an aluminum compound to a heated film-forming object, and oxidizing the aluminum compound to form the film-forming object. The aluminum oxide film has a thickness of, for example, 1 to 100 nm, preferably a thickness of 10 to 80 nm, and more preferably a thickness of 20 to 60 nm.

The alumina film of this embodiment can sufficiently reduce the impurity concentration and become good quality. The content of alumina in the alumina film is, for example, 95% by mass or more, preferably 98% by mass or more, and more preferably 99% by mass or more. Such a high-quality alumina film with high purity and thin thickness is useful in the semiconductor field. In this specification, a content of alumina of 90% by mass or more is referred to as an "alumina film". The variation in the thickness of the aluminum oxide film is, for example, less than 10 nm. Here, the variation in the thickness of the alumina film refers to the difference (maximum value-minimum value) of the film thickness measured at an arbitrarily selected position. [Example]

Next, the present invention will be specifically described with examples, and the scope of the present invention is not limited to these.

Example A1 (Synthesis of methyl aluminum dihalide (compound of formula (2))) A 100-mL flask equipped with a stirring device, a thermometer, and a dropping funnel was charged with 13.0 g (97.5 mmol) of aluminum trichloride and toluene. 50 mL and cooled. When the internal temperature was adjusted to 0 to 6 ° C, 3.50 g (48.8 mmol) of trimethylaluminum was slowly added dropwise to the obtained solution, and the mixture was stirred at room temperature (25 ° C) for 15 hours. After completion of the reaction, the reaction solution was concentrated, and the obtained concentrate was distilled under reduced pressure (oil bath temperature: 50 ° C, 133.3 Pa) to obtain 8.30 g of methyl aluminum dichloride as a white solid (isolated yield: 50%). Among them, methyl aluminum dichloride is a compound represented by physical property values below. ¹ H-NMR (C ₆ D ₆ , δ (ppm)): -0.45 (3H, s)

Example A2 (Synthesis of ethyl aluminum dichloride (compound of formula (3))) Into a 100-mL flask equipped with a stirring device, a thermometer, and a dropping funnel, 7.00 g (52.5 mmol) of aluminum trichloride, 30 mL of toluene and cooled. When the internal temperature was set to 0 to 6 ° C, 3.00 g (26.3 mmol) of triethylaluminum was slowly added dropwise to the obtained solution, and the mixture was stirred at room temperature (25 ° C) for 15 hours. After completion of the reaction, the reaction solution was concentrated, and the obtained concentrate was subjected to distillation under reduced pressure (oil bath temperature 100 ° C, 1333 Pa) to obtain 9.1 g of ethyl aluminum dichloride as a white solid (isolated yield: 91%). Among them, ethyl aluminum dichloride is a compound represented by physical property values below. ¹ H-NMR (C ₆ D ₆ , δ (ppm)): 0.21 (2H, q), 0.93 (3H, t)

Example B1 (manufacturing of an aluminum oxide film) The ethyl aluminum dichloride (compound of formula (3)) synthesized in Example A2 was used to form an aluminum oxide film by the ALD method. In addition, when the film thickness of the formed alumina film was measured, the composition was analyzed together. The analysis of the composition was performed using an XPS (X-ray photoelectron spectroscopy) measurement device. Next, the production of the alumina film will be described in more detail.

As the aluminum compound, ethyl aluminum dichloride synthesized in Example A2, that is, a compound represented by the above formula (3) was used, and an aluminum oxide film was formed on the substrate by the ALD method. The film formation of the alumina film was performed using the apparatus shown in FIG.

The apparatus shown in FIG. 1 includes a gasifier 1 (Ampoule made by SUS) for vaporizing an aluminum compound 2 and a gasifier 6 (Ampoule made by SUS) that vaporizes water 7 to supply water vapor as a reactive gas. A substrate 15 and a heater 14 that heats the substrate 15, and includes a reactor 11 that reacts the aluminum compound 2 with water vapor to form an aluminum oxide film on the substrate 15. The reactor 11 is connected to a vacuum pump via a flow path. A pressure gauge 13, a pressure regulating valve 12, and a trap 16 are provided in the flow path. As a result, the pressure in the reactor 11 is adjusted to a predetermined range. The gas discharged from the reactor 11 is exhausted into the air through the trap 16 and the vacuum pump.

In the gasifier 1 and the gasifier 6 each provided with the heater 3 and the thermostatic bath 8, the aluminum compound 2 and water 7 synthesized in the above-mentioned Example A2 are respectively housed. For the gasifier 1, the flow rate is adjusted by a mass flow controller 4, and argon gas preheated by the preheater 5 is supplied. As a result, argon gas containing the aluminum compound 2 was introduced into the reactor 11 from the gasifier 1.

On the other hand, from the gasifier 6, vaporized water vapor adjusted to a constant temperature by the thermostatic bath 8 is introduced into the reactor 11. Argon gas containing the aluminum compound 2 from the gasifier 1 and water vapor from the gasifier 6 were alternately introduced into the reactor 11. The amounts of argon and water vapor contained in the aluminum compound 2 were adjusted by the pump 17 and the pump 18, respectively. The argon gas and the water vapor containing the aluminum compound 2 were introduced into the reactor 11 along with the argon gas for dilution, which was adjusted by the mass flow controller 9 and preheated by the preheater 10.

The aluminum compound 2 and water 7 are alternately supplied to the reactor 11, and an aluminum oxide film 20 is formed on the substrate 15 heated to a predetermined temperature by the heater 14. The operating conditions of the apparatus of Fig. 1 are as follows.

(Film forming conditions) Gasification temperature of aluminum compound 2 (gasifier 1): 70 ° C Argon carrier flow: 5mL / min. (Adjusted by mass flow controller 4) Supply time of aluminum compound 2: 1 second aluminum Compound 2 rinse time: 5 seconds Water 7 gasification temperature: 10 ° C Water 7 supply time: 1 second Water 7 rinse time: 5 seconds Dilution Ar flow rate: 50mL / min. Material of substrate 15: SiO ₂ / Si size of substrate 15: length × width = 20mm × 20mm temperature of substrate 15: 300 ° C pressure in reactor 11: 1333Pa number of cycles: 500 times (introduction and introduction of argon gas containing aluminum compound 2 from the gasifier The introduction of water vapor of 6 was repeated 500 times.)

An aluminum oxide film 20 is formed on the substrate 15 under the above conditions. The thickness of the formed alumina film 20 was measured using a reflection spectrum film thickness meter. The composition of the alumina film 20 was analyzed using an XPS (X-ray photoelectron spectroscopy) measurement device. The results of the thickness and composition analysis are shown in Table 1.

The thickness of the aluminum oxide film 20 is performed at five locations arbitrarily selected, and the maximum value and the minimum value are obtained. When the maximum 値 -min 値 <10nm, the arithmetic mean is shown in the table. Conversely, when the maximum 値 -min ≧≧ 10 nm, the maximum and minimum values are indicated.

Examples B2 to B6 and Comparative Examples 1 to 2 (manufacturing of alumina film) Except that the temperature of the substrate 15 was changed as shown in Table 1, an alumina film was formed on the substrate 15 in the same manner as in Example B1. 20. The analysis results of the thickness and composition of the formed alumina film 20 are shown in Table 1.

[Table 1]

The thickness of the aluminum oxide films of Examples B1 to B6 was not uneven, and the thickness uniformity was excellent. In addition, it was confirmed that as long as the temperature of the substrate 15 is within a range of 300 to 550 ° C, the composition of the formed film is uniform and the thickness of the alumina film is hardly changed. From this fact, it was confirmed that an aluminum oxide film can be formed stably by using ethyl aluminum dichloride synthesized in Example A2. The alumina content in the alumina films of Examples B1 to B6 was 99% by mass or more, and the content of aluminum carbide was 1% by mass or less.

In the above examples, the aluminum compound represented by the above formula (3) does not naturally ignite. In addition, from the aluminum thin film formed under the above conditions, it is also known that the aluminum compound of the present invention is excellent in reactivity with at least one of a thermally decomposable gas and a reactive gas, and the vapor containing the aluminum compound of the present invention is suitable for a substrate. Excellent surface adsorption. Further, as long as the temperature of the substrate is 300 ° C. to 550 ° C., since the composition of the formed film is only alumina and no halogen atoms remain, it can be known that according to the manufacturing method of the present invention, an alumina film of excellent quality can be manufactured. [Industrial availability]

The invention of this case is that a high-quality alumina film can be manufactured by an industrially appropriate method. In addition, manufacturing materials suitable for the manufacturing method can be provided.

1, 6‧‧‧ gasifier
2‧‧‧ aluminum compounds
3, 14‧‧‧ heater
4.9‧‧‧mass flow controller
5, 10‧‧‧ preheater
7‧‧‧ water
8‧‧‧ constant temperature bath
11‧‧‧ Reactor
12‧‧‧pressure regulating valve
13‧‧‧Pressure gauge
15‧‧‧ substrate
16‧‧‧trap
17, 18‧‧‧ valve
20‧‧‧ alumina film

[FIG. 1] A diagram showing a configuration of a vapor deposition device using an aluminum compound for producing an alumina film used in the examples.

1, 6‧‧‧ gasifier

2‧‧‧ aluminum compounds

3, 14‧‧‧ heater

4.9‧‧‧mass flow controller

5, 10‧‧‧ preheater

7‧‧‧ water

8‧‧‧ constant temperature bath

11‧‧‧ Reactor

12‧‧‧pressure regulating valve

13‧‧‧Pressure gauge

15‧‧‧ substrate

16‧‧‧trap

17, 18‧‧‧ valve

20‧‧‧ alumina film

Claims (7)

An aluminum oxide film manufacturing method is to supply an aluminum compound represented by the following general formula (1) to a film-forming object that has been heated to 300 ° C to 550 ° C, and oxidize it to form an aluminum oxide film; In the formula, R represents a linear alkyl group having 1 to 6 carbon atoms, X represents a halogen group, and two X's may be the same or different. For example, the method for manufacturing an alumina film according to item 1 of the application, wherein the heating temperature of the film-forming object is 480 ° C to 550 ° C. For example, the method for manufacturing an alumina film according to item 1 or 2 of the patent application scope, wherein the alumina film is formed by an atomic layer deposition method. For example, the method for manufacturing an alumina film according to any one of claims 1 to 3 is to simultaneously supply the aluminum compound represented by the general formula (1) and at least one reactive gas selected from water and ozone. For example, in the method for manufacturing an alumina film according to any one of claims 1 to 4, in the general formula (1), R is an ethyl group, and X is a chloro group. For example, the method for manufacturing an alumina film according to any one of claims 1 to 5, wherein the thickness of the alumina film is 10 to 80 nm. A raw material for manufacturing an aluminum oxide film by an atomic layer deposition method is composed of an aluminum compound represented by the following general formula (1); In the formula, R represents a linear alkyl group having 1 to 6 carbon atoms, X represents a halogen group, and two X's may be the same or different.