Raw material composition for forming aluminum oxide film, method for forming aluminum oxide film, aluminum oxide film, and apparatus for manufacturing aluminum oxide film

Abstract

A raw material composition for forming an aluminum oxide film is disclosed, comprising trimethylaluminum and dimethylaluminum hydride. The content of dimethylaluminum hydride in the raw material composition for forming an aluminum oxide film is greater than 0 ppm by mass and less than or equal to 1000 ppm by mass.

Description

[Technical Field]

[0001] This disclosure relates to a raw material composition for forming an aluminum oxide film, a method for forming an aluminum oxide film, an aluminum oxide film, and an apparatus for manufacturing an aluminum oxide film. [Background technology]

[0002] Aluminum oxide films are widely used as coating films for various mechanical parts, gate insulating films for semiconductor integrated circuits, and barrier films in the field of organic electronics. Trimethylaluminum compositions containing trimethylaluminum are known as raw materials for aluminum oxide films. As a method for forming an aluminum oxide film using such a trimethylaluminum composition as a raw material, for example, a method for forming an aluminum-containing oxide thin film is known, in which an aluminum-containing composition containing trimethylaluminum and dimethylaluminum hydride and an oxygen-containing compound containing oxygen atoms are used as raw materials and an aluminum-containing oxide thin film is formed by atomic layer deposition (ALD). Patent document 1 below describes that the film formation rate can be improved by mixing trimethylaluminum and dimethylaluminum hydride in a molar ratio of 4:6 to 8:2. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2016-141882 [Overview of the project] [Problems that the invention aims to solve]

[0004] Incidentally, semiconductors in particular employ highly miniaturized and highly three-dimensional structures, and in order to use trimethylaluminum raw materials in such applications, the development of technology to uniformly produce an aluminum oxide film with a thickness of several nanometers to tens of nanometers on the surface of a three-dimensional substrate is required.

[0005] However, in the method for forming an aluminum oxide film described in Patent Document 1, when an aluminum oxide film is formed on the surface of a substrate having a surface with both a flat surface and a concave surface such as a groove, the difference in film thickness between the aluminum oxide film on the flat surface and the aluminum oxide film on the concave side surface (for example, the deep side surface of a groove) becomes large, leaving room for improvement in terms of so-called step coverage.

[0006] The present disclosure aims to provide a raw material composition for forming an aluminum oxide film, a method for forming an aluminum oxide film, an aluminum oxide film, and an apparatus for manufacturing an aluminum oxide film, which can improve the step coverage of an aluminum oxide film even when forming an aluminum oxide film on the surface of a three-dimensional substrate. [Means for solving the problem]

[0007] The inventors of this disclosure, after diligent research to solve the above problems, have found that by reacting a composition containing trimethylaluminum and dimethylaluminum hydride, with a sufficiently low dimethylaluminum hydride content, with an oxygen atom-containing gas, as a raw material for forming an aluminum oxide film, with a reaction gas, the step coverage of the aluminum oxide film can be improved even when forming an aluminum oxide film on the surface of a three-dimensional substrate, and have completed this disclosure.

[0008] In other words, the content of the present invention is as described in the claims, and the gist of this disclosure is as follows. [1] A raw material composition for forming an aluminum oxide film, comprising trimethylaluminum and dimethylaluminum hydride, The raw material composition for forming an aluminum oxide film, wherein the content of dimethylaluminum hydride in the raw material composition for forming an aluminum oxide film is more than 0 mass ppm and 1000 mass ppm or less. [2] The raw material composition for forming an aluminum oxide film according to [1], wherein the content of dimethylaluminum hydride in the raw material composition for forming an aluminum oxide film is 100 mass ppm or more and 1000 mass ppm or less. [3] The raw material composition for forming an aluminum oxide film according to [1] or [2], which does not contain dimethylaluminum chloride. [4] The content of boron in the raw material composition for forming an aluminum oxide film is 100×10 -9 mol / g or less, and the content of chlorine is 300×10 -9 mol / g or less. The raw material composition for forming an aluminum oxide film according to any one of [1] to 3. [5] The total content of chromium and iron in the raw material composition for forming an aluminum oxide film is 3×10 -9 mol / g or less. The raw material composition for forming an aluminum oxide film according to any one of [1] to [4]. [6] A method for forming an aluminum oxide film, comprising a reaction step of adhering the raw material composition for forming an aluminum oxide film according to any one of [1] to [5] to the surface of a substrate as a raw material and reacting the raw material with a reaction gas containing an oxygen atom-containing gas. [7] The method for forming an aluminum oxide film according to [6], wherein the reaction gas contains ozone. [8] The method for forming an aluminum oxide film according to [6] or [7], wherein the reaction step is performed using an atomic layer deposition method. [9] An aluminum oxide film obtained by the method for forming an aluminum oxide film according to any one of [6] to [8].

[10] A raw material supply unit for supplying the raw material composition for forming an aluminum oxide film according to any one of [1] to [5], A reaction gas supply unit for supplying a reaction gas containing an oxygen atom-containing gas, A reaction chamber for reacting the aluminum oxide film-forming raw material composition supplied from the raw material supply unit and the reaction gas supplied from the reaction gas supply unit, An aluminum oxide film manufacturing apparatus equipped with the following features. [Effects of the Invention]

[0009] According to this disclosure, a raw material composition for forming an aluminum oxide film, a method for forming an aluminum oxide film, an aluminum oxide film, and an apparatus for manufacturing an aluminum oxide film are provided that can improve the step coverage of an aluminum oxide film even when forming an aluminum oxide film on the surface of a three-dimensional substrate. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram showing one embodiment of the aluminum oxide film manufacturing apparatus of the present disclosure. [Figure 2] Figures 2(a) to (e) show TEM images of the cross-sections of the aluminum oxide films obtained in Examples 1 to 3 and Comparative Examples 1 to 2. [Modes for carrying out the invention]

[0011] Embodiments of this disclosure will be described in detail with reference to an example. However, this disclosure is not limited to the following embodiments. Furthermore, this disclosure includes any combination of the configurations and parameters disclosed herein, as well as any combination of the upper and lower limits of the numerical values ​​disclosed herein.

[0012] <Raw material composition for forming aluminum oxide film> First, one embodiment of the raw material composition for forming an aluminum oxide film according to this disclosure will be described.

[0013] The raw material composition for forming aluminum oxide films (hereinafter also referred to as the "raw material composition") contains trimethylaluminum (hereinafter also referred to as "TMA") and dimethylaluminum hydride (hereinafter also referred to as "DMAH"). The DMAH content in the raw material composition is greater than 0 ppm by mass and less than or equal to 1000 ppm by mass.

[0014] According to the above raw material composition, even when an aluminum oxide film is formed on the surface of a three-dimensional substrate using the raw material composition as a raw material, the step coverage by the aluminum oxide film can be improved. Therefore, if the three-dimensional substrate is a substrate having a surface that includes a plane and a concave surface such as a groove, the difference between the film thickness of the aluminum oxide film on the plane and the film thickness of the aluminum oxide film on the side surface of the concave surface (for example, the deep side surface of a groove) can be reduced, and the uniformity of the film thickness on the surface of the three-dimensional substrate can be improved.

[0015] The raw material composition of this embodiment will be described in detail below.

[0016] (DMAH) The DMAH content in the raw material composition should be greater than 0 ppm by mass and 1000 ppm by mass or less, for example, 800 ppm by mass or less, 700 ppm by mass or less, 600 ppm by mass or less, 500 ppm by mass or less, 400 ppm by mass or less, or 300 ppm by mass or less. The DMAH content in the raw material composition may be 0.1 ppm by mass or more, 10 ppm by mass or more, 30 ppm by mass or more, 50 ppm by mass or more, 100 ppm by mass or more, 120 ppm by mass or more, or 140 ppm by mass or more. The DMAH content in the raw material composition may be greater than 0 ppm by mass and 800 ppm by mass or less, 0.1 ppm by mass and 800 ppm by mass or less, or 0.1 ppm by mass and 700 ppm by mass or less. The DMAH content in the raw material composition is preferably 100 ppm by mass or more and 1000 ppm by mass or less, more preferably 120 ppm by mass or more and 800 ppm by mass or less, and particularly preferably 140 ppm by mass or more and 700 ppm by mass or less. When the DMAH content in the raw material composition is 100 ppm by mass or more and 1000 ppm by mass or less, even when an aluminum oxide film is formed on the surface of a three-dimensional substrate using the raw material composition as the raw material, the step coverage by the aluminum oxide film can be further improved. The DMAH content refers to the DMAH content when the raw material composition is in the liquid phase, and can be measured by NMR (nuclear magnetic resonance spectroscopy).

[0017] (TMA) The TMA content in the raw material composition may be 90% by mass or more, 95% by mass or more, 97% by mass or more, 98.5% by mass or more, 99% by mass or more, 99.5% by mass or more, 99.8% by mass or more, 99.9% by mass or more, or 99.99% by mass or more. The TMA content refers to the TMA content when the raw material composition is in the liquid phase, and can be measured using a gas chromatograph (for example, Shimadzu Corporation's GC-8A).

[0018] (Boron and chlorine) The boron and chlorine content in the raw material composition is not particularly limited, however, the boron content in the raw material composition is 100 × 10 -9 The chlorine content in the raw material composition is 300 × 10⁻⁶ or less (mol / g or less) -9 It is preferable that the concentration is mol / g or less. By limiting the content of both boron and chlorine, the amount of Me2BCl and / or BCl3 produced is limited to a maximum of 100 × 10⁻¹⁰ -9 The amount can be reduced to mol / g. As a result, the amount of volatile compounds of Cr and Fe (compounds that worsen film thickness uniformity) generated due to Me2BCl and / or BCl3 can be suppressed. Consequently, the film thickness uniformity on the surface of the three-dimensional substrate can be further improved. The boron content is the boron content in the state where the raw material composition is in a liquid phase, and can be measured by ICP-MS (inductively coupled plasma mass spectrometry, for example, Agilent 8900 manufactured by Agilent). Examples of the volatile compounds of Cr and Fe include CrO2Cl2, Me2CrCl, Me2FeCl, and FeCl3. The boron content in the raw material composition is 50×10 -9 mol / g or less, 30×10 -9 mol / g or less, or 10×10 -9 mol / g or less may also be acceptable. The boron content in the raw material composition is 0.1×10 -9 mol / g or more, 1×10 -9 mol / g or less, or 3×10 -9 mol / g or more may also be acceptable. Examples of the boron content in the raw material composition include 0.1×10 -9 mol / g or more and 50×10 -9 mol / g or less, 1×10 -9 mol / g or more and 30×10 -9 mol / g or less, 3×10 -9 mol / g or more and 10×10 -9 mol / g or less.

[0019] The chlorine content in the raw material composition is 3,00×10 -9 mol / g or less, 2,000×10 -9 mol / g or less, or 1,000×10 -9 mol / g or less may also be acceptable. The chlorine content in the raw material composition is 1×10 -9 mol / g or more, 10×10 -9 mol / g or less, or 30×10 -9 mol / g or more may also be acceptable. Examples of the chlorine content in the raw material composition include 1×10 -9 mol / g or more and 3,000×10 -9 mol / g or less, 10×10 -9 mol / g or more and 2,000×10 -9 mol / g or less, 30×10 -9mol / g or more 1,000×10 -9 Examples include concentrations below mol / g. The chlorine content refers to the chlorine content when the raw material composition is in the liquid phase, and can be measured using UV-Vis (ultraviolet-visible light spectroscopy, for example, Hitachi High-Technologies Corporation's U-1900).

[0020] (Chromium and iron) The total content of chromium and iron in the raw material composition is not particularly limited, but 3 × 10 -9 It is preferable that the amount is 3 × 10⁻⁶ mol / g or less. Even if a small amount of Me₂BCl and / or BCl₃ is produced, the amount of chromium and iron is 3 × 10⁻⁶ -9 By keeping the concentration below mol / g, the amount of volatile compounds such as chromium and iron produced will be limited to a maximum of 3 × 10⁻⁶. -9 It can be reduced to mol / g. As a result, the uniformity of the film thickness on the surface of the three-dimensional substrate can be further improved. The total content of chromium and iron in the raw material composition is 3 × 10 -9 mol / g or less, 2×10 -9 mol / g or less or 1 × 10⁻⁶ -9 It may be less than mol / g. The total content of chromium and iron in the raw material composition is 0.01 × 10⁻⁶. -9 mol / g or more, 0.05×10 -9 mol / g or more or 0.10 × 10 -9 It may be mol / g or higher. The total content of chromium and iron in the raw material composition is 0.01 × 10⁻⁶. -9 mol / g or more 3×10 -9 mol / g or less, 0.05×10 -9 mol / g or more 2×10 -9 mol / g or less, 0.10×10 -9 mol / g or more 1×10 -9 Examples include concentrations below mol / g.

[0021] The chromium and iron content refers to the content of chromium and iron when the raw material composition is in the liquid phase, and can be measured using ICP-MS (dielectric-coupled plasma mass spectrometry, for example, Agilent 8900 from Agilent).

[0022] (Other ingredients) The raw material composition preferably has a composition in which TMA and DMAH make up 100% by mass, but other components may be included as needed, as long as they do not produce the desired effect. Examples of other components include one or more selected from the group consisting of chlorine atom-containing components such as dimethylaluminum chloride, oxygen atom-containing components, ethyl group-containing components, and organosilicon components. The raw material composition does not need to contain dimethylaluminum chloride. In other words, the dimethylaluminum chloride content in the raw material composition may be 0 ppm by mass.

[0023] <Method for forming an aluminum oxide film> Next, embodiments of the method for forming an aluminum oxide film according to this disclosure will be described. The method for forming an aluminum oxide film in this embodiment includes a reaction step in which the above-described raw material composition is attached to the surface of a substrate as a raw material, and the raw material is reacted with a reaction gas containing an oxygen atom gas. In this specification, the method for forming an aluminum oxide film refers to a method for manufacturing an aluminum oxide film, and a method for forming an aluminum oxide film.

[0024] This formation method makes it possible to improve the step coverage of the aluminum oxide film even when forming an aluminum oxide film on the surface of a three-dimensional substrate.

[0025] Next, the above formation method will be explained in detail.

[0026] In the above formation method, first, the raw material composition described above is attached to the surface of the substrate as a raw material. Examples of three-dimensional substrates include substrates with grooves formed on their surface and substrates with irregularities formed on their surface. This disclosure is particularly useful when forming an aluminum oxide film on the surface of a three-dimensional substrate. In this disclosure, it is preferable to use the above-described raw material composition for forming an aluminum oxide film on the surface of a three-dimensional substrate having grooves or holes formed on its surface. The substrate is placed, for example, inside a reaction chamber. When a substrate having grooves or holes (hereinafter, grooves and holes are collectively referred to as "grooves, etc.") formed on its surface is used as the base for a three-dimensional structure, the width of the grooves, etc. is not particularly limited, but is preferably 1 nm or more, more preferably 10 nm or more, and particularly preferably 15 nm or more. The width of the grooves, etc., is preferably 100 nm or less, more preferably 50 nm or less, and particularly preferably 20 nm or less. Examples of groove widths include 1 nm to 100 nm, 10 nm to 50 nm, or 10 nm to 20 nm. The depth of grooves, etc., from the surface is not particularly limited, but is preferably 0.001 μm or more, more preferably 0.01 μm or more, and especially preferably 0.1 μm or more. The depth of grooves and other features from the surface is preferably 10 μm or less, more preferably 5 μm or less, and particularly preferably 1 μm or less. Examples of groove depths from the surface include 0.001 μm to 10 μm, 0.01 μm to 5 μm, or 0.1 μm to 1 μm. The ratio of the depth of the groove from the surface to the width of the groove (hereinafter referred to as the "aspect ratio") is not particularly limited, but is preferably 0.1 or more, more preferably 1 or more, particularly preferably 2 or more, and even more preferably 5 or more. The aspect ratio is preferably 1000 or less, more preferably 100 or less, and particularly preferably 10 or less. Examples of aspect ratios include 0.1 to 1000, 1 to 100, 5 to 100, or 2 to 10. In particular, for substrates with grooves or the like formed on the surface, substrates with grooves or the like having a width of 10 nm to 20 nm, a depth of grooves or the like from the surface of 0.1 μm to 1 μm, and an aspect ratio of 5 to 100 are preferred.

[0027] The raw materials attached to the surface of the substrate consist of the raw material composition described above. Here, since the raw material composition is in the liquid phase at room temperature and pressure, it is attached to the surface of the substrate by bringing it into contact with it in a vaporized state.

[0028] The temperature of the substrate is not particularly limited, but is preferably 100°C or higher, more preferably 150°C or higher, and especially preferably 200°C or higher, because it results in a good composition of the resulting film. However, the substrate temperature is preferably 600°C or lower, more preferably 500°C or lower, and particularly preferably 400°C or lower, for the reason that the resulting film has good surface smoothness. The temperature of the substrate can be measured, for example, using a thermocouple or commercially available thermotape.

[0029] While there are no particular restrictions on the raw material supply time, from the viewpoint of improving the step coverage by the aluminum oxide film, it is preferably 0.1 seconds or more, more preferably 0.5 seconds or more, and most preferably 1 second or more. There is no particular upper limit on the raw material supply time, but it is preferable to supply the raw material for 60 seconds or less in order to quickly form the film.

[0030] The pressure of the atmosphere surrounding the substrate (e.g., the atmosphere inside the reaction chamber) is not particularly limited, but is usually below atmospheric pressure and is preferably 3990 Pa or less, more preferably 1330 Pa or less, and especially preferably 665 Pa or less, for the reason that the composition of the resulting film is good.

[0031] It is preferable to exhaust any excess raw material gas. In this case, the reaction between the reaction gas and the attached raw material is less likely to be inhibited by the excess raw material gas. Exhaust can be performed by either reducing the pressure or purging with an inert gas. Each method, either by reducing the pressure or purging with an inert gas, may be performed individually or in combination. Examples of inert gases include noble gases such as argon, and nitrogen. These may be used individually or in mixtures of two or more.

[0032] After the raw materials are attached to the surface of the substrate, the raw materials are reacted with a reaction gas containing oxygen atoms. Examples of oxygen atom-containing gases include water vapor, oxygen, hydrogen peroxide, and ozone. These may be used individually or in combination of two or more. The oxygen atom-containing gas preferably contains ozone. Ozone has a higher oxidizing power than water vapor and oxygen. As a result, the reaction proceeds efficiently, the aluminum oxide film is formed efficiently, and the step coverage of the aluminum oxide film is further improved. The aluminum oxide film is formed by the reaction of the reaction gas with the raw materials. It is preferable to exhaust any excess reaction gas. In this case, the adhesion of subsequently supplied raw materials to the aluminum oxide film is prevented from being inhibited by the excess reaction gas. Exhaust can be performed by either reducing the pressure or purging with an inert gas. Each method, either by reducing the pressure or purging with an inert gas, may be performed individually or in combination. Examples of inert gases include noble gases such as argon, and nitrogen. These may be used individually or in mixtures of two or more.

[0033] The film deposition temperature can be adjusted, for example, by heating the substrate. The film deposition temperature is not particularly limited as long as it is above the reaction initiation temperature, but examples of film deposition temperatures include 400°C or lower, 300°C or lower, 200°C or lower, 150°C or lower, or 100°C or lower.

[0034] The supply time of the reaction gas is not particularly limited, but from the viewpoint of improving the step coverage by the aluminum oxide film, it is preferably 0.5 seconds or more, more preferably 1 second or more, and particularly preferably 2 seconds or more. There is no particular upper limit to the supply time of the reaction gas, but the supply time of the reaction gas is preferably 60 seconds or less in order to quickly form the film.

[0035] The above reaction step may be performed only once or multiple times. The number of reaction steps can be appropriately determined according to the thickness of the aluminum oxide film formed on the surface of the substrate. The reaction process may be carried out by chemical vapor deposition (CVD) or atomic layer deposition (ALD), but from the viewpoint of further improving the step coverage of the aluminum oxide film, it is preferable to use the ALD method.

[0036] In the reaction process, the vapor pressure of DMAH is higher than that of TMA in the liquid phase of the raw material composition, which tends to reduce the DMAH content in the raw material composition. Therefore, it is preferable to adjust the DMAH content in the raw material composition to a constant level as needed. In this case, the quality of the resulting aluminum oxide film can be stabilized. The DMAH content can be adjusted, for example, by supplying DMAH to the raw material composition.

[0037] <Aluminum oxide film manufacturing equipment> Next, an embodiment of the aluminum oxide film manufacturing apparatus of this disclosure will be described with reference to Figure 1. As shown in Figure 1, the aluminum oxide film manufacturing apparatus 100 comprises a raw material supply unit 10 for supplying the raw material composition described above, a reaction gas supply unit 20 for supplying a reaction gas containing oxygen atoms, and a reaction chamber 30 for reacting the aluminum oxide film forming raw material composition supplied from the raw material supply unit 10 with the reaction gas supplied from the reaction gas supply unit 20. The reaction gas supply unit 20 may further include an ozone supply source as needed. An ozone supply source specifically refers to an ozone generator.

[0038] Furthermore, a support section 32 for supporting the substrate 31 may be installed inside the reaction chamber 30. The aluminum oxide film manufacturing apparatus 100 may further include a carrier / dilution gas supply unit 40 for supplying a carrier gas and a dilution gas. The aluminum oxide film manufacturing apparatus 100 may be equipped with a reaction gas purge line L1, a purge-up gas line L2, and a raw material gas purge line L3 connecting the carrier / dilution gas supply unit 40 and the reaction chamber 30, and mass flow controllers M1, M2, and M3 may be installed in the reaction gas purge line L1, the purge-up gas line L2, and the raw material gas purge line L3, respectively. The aluminum oxide film manufacturing apparatus 100 may further include a raw material gas supply line L4 connecting the raw material gas purge line L3 and the raw material supply unit 10, and a reaction gas supply line L5 connecting the reaction gas purge line L1 and the reaction gas supply unit 20. A valve V1 and a mass flow controller M4 may be installed in the raw material gas supply line L4. A mass flow controller M5 may be installed in the reaction gas supply line L5. Furthermore, the aluminum oxide film manufacturing apparatus 100 may also be equipped with an exhaust line L6 connected to the reaction chamber 30, and a valve V3 and an exhaust pump 50 may be installed in this order from the reaction chamber 30 in the exhaust line L6. A branch line L7 may be installed in the exhaust line L6, and a flow rate variable valve V2 may be installed in the branch line L7.

[0039] According to the aluminum oxide film manufacturing apparatus 100, the above-mentioned raw material composition is used as a raw material, and the process includes the following steps (1) and (5), and may also include steps (2) to (4) and (6) to (8). The aluminum oxide film is formed by performing the reaction step one or more times. Furthermore, steps (2) to (4) and (6) to (8) may be added or omitted as needed, or may be performed simultaneously. In this case, even when an aluminum oxide film is formed on the surface of the three-dimensional substrate 31, the step coverage provided by the aluminum oxide film can be improved.

[0040] (1) First, with valve V1 and variable flow valve V2 open and V3 closed, exhaust is performed by exhaust pump 50, and the raw material is supplied from the raw material supply unit 10 in a vaporized state through the raw material gas supply line L4 and raw material gas purge line L3 into the reaction chamber 30, and is allowed to adhere to the surface of the substrate 31. At this time, the pressure inside the reaction chamber 30 may be adjusted by adjusting the opening of the variable flow valve V2. (2) Next, after closing valve V1 to stop the supply of raw materials, the exhaust pump 50 is used to exhaust the gas in the reaction chamber 30 through the exhaust line L6. At this time, the variable flow valve V2 may be closed and then valve V3 may be opened to perform the exhaust. (3) Next, if necessary, dilution gas may be supplied from the carrier / dilution gas supply unit 40 to the reaction chamber 30 through the raw material gas purge line L3 to purge excess raw material gas and exhaust it from the reaction chamber 30 through the exhaust line L6, while also adjusting the pressure inside the reaction chamber 30. The pressure inside the reaction chamber 30 can be adjusted by closing valve V3 and adjusting the opening of the flow rate variable valve V2. (4) Next, the supply of dilution gas from the carrier / dilution gas supply unit 40 is stopped, and with valve V3 open, the gas in the reaction chamber 30 is exhausted through the exhaust line L6 by the exhaust pump 50. (5) Next, with valve V3 closed and flow rate variable valve V2 open, reaction gas is supplied from the reaction gas supply unit 20 to the reaction chamber 30 through the reaction gas supply line L5 and the reaction gas purge line L1, and the reaction gas is brought into contact with the raw materials attached to the surface of the substrate 31 to react and form an aluminum oxide film. At this time, the pressure inside the reaction chamber 30 may be adjusted by adjusting the opening of the flow rate variable valve V2. (6) Next, after stopping the supply of reaction gas, the gas in the reaction chamber 30 is exhausted through the exhaust line L6 by the exhaust pump 50. (7) Next, if necessary, dilution gas may be supplied from the carrier / dilution gas supply unit 40 to the reaction chamber 30 through the reaction gas purge line L1 to purge excess reaction gas and exhaust it from the reaction chamber 30 through the exhaust line L6, while also adjusting the pressure inside the reaction chamber 30. The pressure inside the reaction chamber 30 can be adjusted by closing valve V3 and adjusting the opening of the flow rate variable valve V2. (8) Next, the supply of dilution gas from the carrier / dilution gas supply unit 40 is stopped, and with valve V3 open, the gas in the reaction chamber 30 is exhausted through the exhaust line L6 by the exhaust pump 50. [Examples]

[0041] The contents of this disclosure will be explained in more detail below using examples, but this disclosure is not limited to the following examples.

[0042] (Example 1) Using the aluminum oxide film manufacturing apparatus 100 shown in Figure 1, an aluminum oxide film was manufactured by repeating the reaction process consisting of the following steps (1) to (6) for 105 cycles, with each cycle being considered one cycle, under the following manufacturing conditions. At this time, the raw material supplied by the raw material supply unit 10 was a liquid-phase raw material composition containing TMA and DMAH, with a DMAH content of 30 ppm by mass, and the reaction gas supplied by the reaction gas supply unit 20 was a mixed gas of oxygen and ozone. The aluminum oxide film was manufactured on the surface of the substrate using the ALD method. The TMA content in the raw material composition was determined using the following procedure. First, a solution of the raw material composition diluted fourfold with liquid paraffin was dropped into an acidic aqueous solution, and the generated gas was collected. The methane concentration in the gas was measured using a gas chromatograph (Shimadzu Corporation, GC-8A), and the mass content of TMA in the raw material composition was calculated from the results. The DMAH content in the raw material composition was calculated using the internal standard method. Specifically, the raw material composition was diluted with deuterated benzene containing anisole as an internal standard substance, and then proton NMR was measured using an NMR (nuclear magnetic resonance) spectrometer (JEOL Ltd., JNM-ECA 500). The DMAH content was calculated by comparing the integral values ​​of the anisole peak and the DMAH peak. <Manufacturing conditions> Raw material gas: Supplyed at room temperature after complete extraction. Purge gas to be supplied to raw material gas purge line L3: Argon (flow rate: 10 sccm) Reaction gas: Mixture of ozone and oxygen (flow rate: 25 sccm) Purge gas to be supplied to the reaction gas purge line: Argon (flow rate: 20 sccm) Purge gas to be supplied to purge gas line L2: Argon (flow rate: 50 sccm) Substrate: Line and space pattern substrate with groove width of 50 nm, depth of 1 μm from the surface, and aspect ratio of 20. Substrate temperature: 200°C (during raw material gas supply and reaction gas supply) Total pressure in the reaction chamber: 133 Pa (during raw material gas supply and reaction gas supply) Furthermore, "cut-off supply" refers to supplying the raw materials to the reaction chamber 30 by reducing the pressure of the pump 50, without blowing gas into the raw material supply unit 10, and vaporizing the steam at room temperature.

[0043] <Reaction Process> (1) With valve V1 and variable flow valve V2 open and valve V3 closed, exhaust is performed by exhaust pump 50, and the raw material vaporized at room temperature is supplied from the raw material supply unit 10 to the reaction chamber 30 through the raw material gas supply line L4 and raw material gas purge line L3, with the flow rate adjusted by the mass flow controller M4, and allowed to adhere to the surface of the substrate for 2 seconds. (2) After closing valve V1 and mass flow controller M4 to stop the supply of raw materials, close the variable flow valve V2 and open valve V3, and exhaust pump 50 to exhaust the inside of reaction chamber 30 for 1 second. (3) Argon is supplied from the carrier / dilution gas supply unit 40 to the reaction chamber 30 for 5 seconds through the raw material gas purge line L3 to purge any unreacted raw materials in the reaction chamber 30 and exhaust them through the exhaust line L6, while also adjusting the pressure in the reaction chamber 30. The pressure in the reaction chamber 30 is adjusted by closing valve V3 and adjusting the opening of valve V2, as well as by adjusting the amount of argon supplied from the carrier / dilution gas supply unit 40 using the mass flow controller M3. (4) With the pressure adjusted using the variable flow valve V2, the reaction gas with the adjusted flow rate is supplied from the reaction gas supply unit 20 to the reaction chamber 30 for 3 seconds through the mass flow controller M5, the reaction gas supply line L5 and the reaction gas purge line L1, and reacts with the raw materials attached to the surface of the substrate 31 to form an aluminum oxide film. (5) After closing the mass flow controller M5 to stop the supply of reaction gas, the variable flow valve V2 is closed and the valve V3 is opened, and the inside of the reaction chamber 30 is exhausted for 1 second through the exhaust line L6 by the exhaust pump 50. (6) Argon is supplied from the carrier / dilution gas supply unit 40 to the reaction chamber 30 for 5 seconds through the reaction gas purge line L1 to purge excess reaction gas from the reaction chamber 30 and exhaust it through the exhaust line L6, while also adjusting the pressure inside the reaction chamber 30. The pressure inside the reaction chamber 30 is adjusted by closing valve V3 and adjusting the opening of valve V2, as well as by adjusting the amount of argon supplied from the carrier / dilution gas supply unit 40 using the mass flow controller M1.

[0044] The surface roughness Rms of the aluminum oxide film obtained as described above was measured using an atomic force microscope (AFM), and the Rms was found to be 0.27 nm, confirming that a smooth film had been produced. Furthermore, the aluminum oxide film was cut and cross-sectional TEM (Transmission Electron Microscope) observation was performed. The cross-sectional TEM image is shown in Figure 2(a). The cross-sectional TEM image is shown divided into three regions, the first, second, and third, in the direction of groove depth from the surface. Here, in the first region, the thickness of the aluminum oxide film on the substrate surface was defined as a, the thickness of the aluminum oxide film on the inner surface of the groove at a depth of 100 nm from the substrate surface was defined as b, in the second region, the thickness of the aluminum oxide film on the inner surface of the groove at a depth of 500 nm from the substrate surface was defined as c, and in the third region, the thickness of the aluminum oxide film on the inner surface of the groove at a depth of 950 nm from the substrate surface was defined as d. From Figure 2(a), it was confirmed that aluminum oxide grew on the substrate surface with a thickness of a = 9.6 nm, and in the third region of the groove inner surface, it grew on the inner surface of the groove at a depth of 950 nm from the substrate surface with a thickness of d = 9.1 nm. From these thicknesses, the step coverage rate by the aluminum oxide film was calculated based on the following formula (A). The results are shown in Table 1. As shown in Table 1, the step coverage rate was 94.8%. Step Coverage Ratio = 100 × Film thickness at a depth of 950 nm from the surface in the third region / Film thickness on the substrate surface ... (A)

[0045] (Example 2) An aluminum oxide film was obtained in the same manner as in Example 1, except that a liquid-phase raw material composition with a DMAH content of 140 ppm by mass was used as the raw material. The surface roughness Rms of the obtained aluminum oxide film was measured using AFM, and it was found to be 0.27 nm, confirming that a smooth film had been produced. Furthermore, the aluminum oxide film was cut and cross-sectional TEM observation was performed. The cross-sectional TEM image is shown in Figure 2(b). Similar to Example 1, the cross-sectional TEM image is shown divided into three regions, the first, second, and third, in the groove depth direction from the surface side. From Figure 2(b), it was confirmed that aluminum oxide grew on the substrate surface with a thickness of a=9.4 nm, and in the third region, it grew on the inner surface of the groove at a depth of 950 nm from the substrate surface with a thickness of d=9.0 nm. The step coverage rate by the aluminum oxide film was calculated from these film thicknesses based on the above formula (A). The results are shown in Table 1. As shown in Table 1, the step coverage rate was 95.7%.

[0046] (Example 3) An aluminum oxide film was obtained in the same manner as in Example 1, except that a liquid-phase raw material composition with a DMAH content of 600 ppm by mass was used as the raw material. The surface roughness Rms of the obtained aluminum oxide film was measured using AFM, and it was found to be 0.27 nm, confirming that a smooth film had been produced. Furthermore, the aluminum oxide film was cut and cross-sectional TEM observation was performed. The cross-sectional TEM image is shown in Figure 2(c). Similar to Example 1, the cross-sectional TEM image is shown divided into the first, second, and third regions in the groove depth direction, starting from the surface. From Figure 2(c), it was confirmed that aluminum oxide grew on the substrate surface with a thickness of a=10.6 nm, and in the third region, it grew on the inner surface of the groove at a depth of 950 nm from the substrate surface with a thickness of d=10.1 nm. The step coverage rate by the aluminum oxide film was calculated from these film thicknesses based on the above formula (A). The results are shown in Table 1. As shown in Table 1, the step coverage rate was 95.3%.

[0047] (Comparative Example 1) An aluminum oxide film was produced in the same manner as in Example 1, except that a liquid-phase raw material composition with a DMAH content of 1090 ppm by mass was used as the raw material. The surface roughness Rms of the obtained aluminum oxide film was measured by AFM, and it was found to be 0.23 nm, confirming that a smooth film had been produced. Furthermore, the aluminum oxide film was cut and cross-sectional TEM observation was performed. The cross-sectional TEM image is shown in Figure 2(d). Similar to Example 1, the cross-sectional TEM image is shown divided into the first, second, and third regions in the groove depth direction, starting from the surface. From Figure 2(d), it was confirmed that aluminum oxide grew on the substrate surface with a thickness of a=10.4 nm, and in the third region, it grew on the inner surface of the groove at a depth of 950 nm from the substrate surface with a thickness of d=9.6 nm. The step coverage rate by the aluminum oxide film was calculated from these film thicknesses based on the above formula (A). The results are shown in Table 1. As shown in Table 1, the step coverage rate was 92.3%.

[0048] (Comparative Example 2) An aluminum oxide film was obtained in the same manner as in Example 1, except that a liquid-phase raw material composition with a DMAH content of 2320 ppm by mass was used as the raw material. The surface roughness Rms of the obtained aluminum oxide film was measured by AFM, and it was found to be 0.23 nm, confirming that a smooth film had been produced. Furthermore, the aluminum oxide film was cut and cross-sectional TEM observation was performed. The cross-sectional TEM image is shown in Figure 2(e). Similar to Example 1, the cross-sectional TEM image is shown divided into the first, second, and third regions in the groove depth direction, starting from the surface. From Figure 2(e), it was confirmed that aluminum oxide grew on the substrate surface with a thickness of a=9.3 nm, and in the third region, it grew on the inner surface of the groove at a depth of 950 nm from the substrate surface with a thickness of d=6.7 nm. The step coverage rate by the aluminum oxide film was calculated from these film thicknesses based on the above formula (A). The results are shown in Table 1. As shown in Table 1, the step coverage rate was 72.0%.

[0049] For Example 1 and Comparative Example 2, the B, Cl, Cr, and Fe content of the raw material compositions was measured by the following analysis. The results are shown in Table 2. Table 2 also shows the total content of Cr and Fe. (Preparation of analytical samples) The raw material composition to be analyzed was diluted approximately 30 times with an organic solvent, and the resulting solution was added dropwise to an acidic aqueous solution to obtain a hydrolysis solution of the raw material composition. Xylene was used as the organic solvent. (B, Cr, and Fe) The amounts of B, Cr, and Fe contained in the above raw material composition were calculated by measuring the amounts of B, Cr, and Fe in the aqueous layer of the hydrolysis solution using an Agilent 8900 ICP-MS (dielectric-coupled plasma mass spectrometry) instrument, calculating the molar content of each metal atom, and then dividing by the mass (g) of the raw material composition. (Cl) The amount of Cl contained in the above raw material composition was calculated by suspending the aqueous layer of the hydrolysis solution in an aqueous silver nitrate solution, measuring its absorbance with a Hitachi High-Technologies Corporation U-1900 spectrophotometer, calculating the molar content of chlorine atoms, and then dividing it by the mass (g) of the raw material composition.

[0050] [Table 1]

[0051] [Table 2]

[0052] Based on these results, the step coverage ratio in Examples 1-3 was greater than that in Comparative Examples 1-2. From this, it has been confirmed that the raw material composition for forming aluminum oxide films according to this disclosure can improve the step coverage of the aluminum oxide film even when forming an aluminum oxide film on the surface of a three-dimensional substrate. [Explanation of Symbols]

[0053] 10... Raw material supply unit, 20... Reaction gas supply unit, 30... Reaction chamber, 100... Aluminum oxide film manufacturing apparatus.

Claims

1. A raw material composition for forming an aluminum oxide film, comprising trimethylaluminum and dimethylaluminum hydride, A raw material composition for forming an aluminum oxide film, wherein the content of the dimethylaluminum hydride in the raw material composition for forming an aluminum oxide film is greater than 0 ppm by mass and less than or equal to 1000 ppm by mass.

2. The aluminum oxide film forming raw material composition according to claim 1, wherein the content of the dimethylaluminum hydride in the aluminum oxide film forming raw material composition is 100 ppm by mass or more and 1000 ppm by mass or less.

3. A raw material composition for forming an aluminum oxide film according to claim 1 or 2, which does not contain dimethylaluminum chloride.

4. The boron content in the aluminum oxide film forming raw material composition is 100 × 10 －９ mol / g or less, and chlorine content is 300 x 10 －９ A raw material composition for forming an aluminum oxide film according to claim 1 or 2, wherein the concentration is mol / g or less.

5. The total content of chromium and iron in the aluminum oxide film forming raw material composition is 3 × 10 －９ A raw material composition for forming an aluminum oxide film according to claim 1 or 2, wherein the concentration is mol / g or less.

6. A method for forming an aluminum oxide film, comprising a reaction step of adhering the aluminum oxide film-forming raw material composition according to claim 1 or 2 to the surface of a substrate as a raw material, and reacting the raw material with a reaction gas containing an oxygen atom gas.

7. The method for forming an aluminum oxide film according to claim 6, wherein the reaction gas contains ozone.

8. The method for forming an aluminum oxide film according to claim 6, wherein the reaction step is carried out using atomic layer deposition.

9. A raw material supply unit that supplies the raw material composition for forming an aluminum oxide film according to claim 1 or 2, A reaction gas supply unit that supplies a reaction gas containing oxygen atoms, An aluminum oxide film manufacturing apparatus comprising: a raw material composition for forming an aluminum oxide film supplied from the raw material supply unit; and a reaction chamber for reacting the reaction gas supplied from the reaction gas supply unit.

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