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

Abstract

Disclosed is a raw material composition for forming an aluminum oxide film, the raw material composition containing trimethylaluminum and dimethylaluminum hydride. The dimethylaluminum hydride content of the raw material composition for forming an aluminum oxide film is greater than 0 mass ppm and no greater than 1000 mass ppm.

Description

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

[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.

[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 aluminum oxide films using such trimethylaluminum compositions as raw materials, for example, a method for forming aluminum-containing oxide thin films 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 deposition rate can be improved by mixing trimethylaluminum and dimethylaluminum hydride in a molar ratio of 4:6 to 8:2.

[0003] Japanese Patent Publication No. 2016-141882

[0004] Incidentally, semiconductors in particular employ highly miniaturized and highly three-dimensional structures, and in order to use trimethylaluminum as a raw material 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.

[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, wherein the content of dimethylaluminum hydride in the raw material composition for forming an aluminum oxide film is greater than 0 ppm by mass and 1000 ppm by mass 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 ppm by mass or more and 1000 ppm by mass 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 boron content in the raw material composition for forming an aluminum oxide film 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, wherein the amount is mol / g or less, 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[1] A raw material composition for forming an aluminum oxide film according to any one of [1] to [4], wherein the amount is mol / g or less. [6] A method for forming an aluminum oxide film, comprising a reaction step of attaching the raw material composition for forming an aluminum oxide film according to any one of [1] to [5] as a raw material to the surface of a substrate, and reacting the raw material with a reaction gas containing an oxygen atom-containing gas. [7] A method for forming an aluminum oxide film according to [6], wherein the reaction gas contains ozone. [8] A method for forming an aluminum oxide film according to [6] or [7], wherein the reaction step is carried out 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] An aluminum oxide film manufacturing apparatus comprising: 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; and a reaction chamber for reacting the raw material composition for forming an aluminum oxide film supplied from the raw material supply unit and the reaction gas supplied from the reaction gas supply unit.

[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.

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

[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 aluminum oxide film of 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 1000 ppm by mass or less.

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

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

[0018] (Boron and Chlorine) The contents of boron and chlorine in the raw material composition are not particularly limited, but the content of boron in the raw material composition is 100×10 －９ mol / g or less and the content of chlorine in the raw material composition is 300×10 －９It is preferably at most 1 mol / g. By suppressing the contents of both boron and chlorine, Me ２ the production amount of BCl and / or BCl ３ is suppressed to at most 100×10 －９ mol / g. As a result, the production amount of volatile compounds of Cr and Fe (compounds that deteriorate the film thickness uniformity) generated due to Me ２ BCl and / or BCl ３ can be suppressed. As a result, the film thickness uniformity on the surface of the three-dimensional structure substrate can be further improved. The content of boron is the content of boron 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 CrO ２ Cl ２ , Me ２ CrCl, Me ２ FeCl, FeCl ３ . The content of boron in the raw material composition may be 50×10 －９ mol / g or less, 30×10 －９ mol / g or less, or 10×10 －９ mol / g or less. The content of boron in the raw material composition may be 0.1×10 －９ mol / g or more, 1×10 －９ mol / g or less, or 3×10 －９ mol / g or more. Examples of the content of boron 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, and 3×10 －９ mol / g or more and 10×10 －９ mol / g or less.

[0019] The content of chlorine in the raw material composition is 3,000×10 －９ mol / g or less, 2,000×10 －９ mol / g or less, or 1,000×10 －９The chlorine content in the raw material composition may be mol / g or less. －９ mol / g or more, 10×10 －９ mol / g or less or 30 x 10 －９ The chlorine content in the raw material composition may be 1 × 10⁻⁶. －９ mol / g or more 3,000×10 －９ mol / g or less, 10×10 －９ mol / g or more 2,000×10 －９ mol / g or less, 30×10 －９ mol / g or more 1,000×10 －９ Examples include values ​​of mol / g or less. Note that 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 it is mol / g or less. If a small amount of Me ２ BCl and / or BCl ３ Even if it is produced, the amount of chromium and iron is 3 × 10 －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 The amount may be mol / g or less. 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 The amount may be mol / g or more. 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 and 2×10 －９ mol / g or less, 0.10×10 －９ mol / g or more and 1×10 －９ mol / g or less can be exemplified.

[0021] Note that the contents of chromium and iron are the contents of chromium and iron in the state where the raw material composition is in the liquid phase, and can be measured by ICP-MS (inductively coupled plasma mass spectrometry, for example, Agilent 8900 manufactured by Agilent Technologies).

[0022] (Other components) The raw material composition preferably has a composition of 100% by mass with TMA and DMAH, but other components may be included as necessary as long as the effect is achieved. 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 may not contain dimethylaluminum chloride. That is, the content of dimethylaluminum chloride in the raw material composition may be 0 mass ppm.

[0023] <Method for forming aluminum oxide film> Next, embodiments of the method for forming an aluminum oxide film of the present disclosure will be described. The method for forming an aluminum oxide film of this embodiment includes a reaction step of adhering the above-described raw material composition 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. In this specification, the method for forming an aluminum oxide film is a method for manufacturing an aluminum oxide film and a method for forming an aluminum oxide film.

[0024] According to this forming method, even when forming an aluminum oxide film on the surface of a three-dimensional structure substrate, the step coverage of the aluminum oxide film can be improved.

[0025] Next, the above forming method will be described in detail.

[0026] In the above formation method, first, the above-mentioned raw material composition is attached to the surface of a 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-mentioned 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, in 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 three-dimensional substrate, 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, etc., from the surface is preferably 10 μm or less, more preferably 5 μm or less, and especially 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 grooves, etc., from the surface to the width of grooves, etc. (hereinafter referred to as "aspect ratio") is not particularly limited, but is preferably 0.1 or more, more preferably 1 or more, especially 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 especially 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 their surface, substrates with grooves or the like having a width of 10 nm to 20 nm, a depth of 0.1 μm to 1 μm from the surface, 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 substrate temperature is not particularly limited, but is preferably 100°C or higher, more preferably 150°C or higher, and especially preferably 200°C or higher, for the reason that the resulting film has a good composition. However, the substrate temperature is preferably 600°C or lower, more preferably 500°C or lower, and especially preferably 400°C or lower, for the reason that the resulting film has good surface smoothness. The substrate temperature can be measured, for example, by a thermocouple or a commercially available thermotape.

[0029] The raw material supply time is not particularly limited, but 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 to the raw material supply time, but the supply time is preferably 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 particularly 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 prevented from being inhibited by the excess raw material gas. Exhaust can be performed by reducing the pressure or by purging with an inert gas. Reduced pressure and 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. It is preferable that the oxygen atom-containing gas 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 efficiently formed, 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 and 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 done by reducing the pressure or by purging with an inert gas. Reduced pressure and purging with an inert gas may be done individually or in combination. Examples of inert gases include noble gases such as argon and nitrogen. These may be used individually or in combination 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 should be appropriately determined according to the thickness of the aluminum oxide film to be formed on the surface of the substrate. The reaction step may be carried out by chemical vapor deposition (CVD) or atomic layer deposition (ALD), but from the viewpoint of further improving the step coverage by 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 Apparatus> Next, an embodiment of the aluminum oxide film manufacturing apparatus of the present 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 and 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. Specifically, an ozone supply source may be 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 section 40 for supplying carrier gas and dilution gas. The aluminum oxide film manufacturing apparatus 100 may also include 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 section 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 section 10, and a reaction gas supply line L5 connecting the reaction gas purge line L1 and the reaction gas supply section 20, and 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. 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 forming an aluminum oxide film on the surface of a three-dimensional substrate 31, the step coverage by the aluminum oxide film can be improved.

[0040] (1) First, with valve V1 and variable flow valve V2 open and V3 closed, exhaust pump 50 is used to exhaust the raw materials, which have been vaporized, into the reaction chamber 30 from the raw material supply unit 10 through the raw material gas supply line L4 and the raw material gas purge line L3, and they are allowed to adhere to the surface of the substrate 31. At this time, the opening of the variable flow valve V2 may be adjusted to adjust the pressure inside the reaction chamber 30. (2) Next, valve V1 is closed to stop the supply of raw materials, and then the exhaust pump 50 is used to exhaust the gas inside the reaction chamber 30 through the exhaust line L6. At this time, valve V3 may be opened after closing the variable flow valve V2 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 variable flow 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 inside the reaction chamber 30 is exhausted by the exhaust pump 50 through the exhaust line L6. (5) Next, with valve V3 closed and the variable flow 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 variable flow valve V2. (6) Next, after stopping the supply of reaction gas, the gas inside the reaction chamber 30 is exhausted by the exhaust pump 50 through the exhaust line L6. (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.

[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 (1) to (6) below for 105 cycles, with each cycle being 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 by the following procedure. First, a solution of the raw material composition diluted four times 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 result. 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. Proton NMR was then measured using an NMR (nuclear magnetic resonance) spectrometer (JEOL Ltd., JNM-ECA 500), and the integral value of the anisole peak was compared with the integral value of the DMAH peak to calculate the result. <Manufacturing Conditions> Raw material gas: Supplyed in a complete draw at room temperature Purge gas flowing through raw material gas purge line L3: Argon (flow rate: 10 sccm) Reaction gas: Mixed gas of ozone and oxygen (flow rate: 25 sccm) Purge gas flowing through reaction gas purge line: Argon (flow rate: 20 sccm) Purge-up gas flowing through purge-up gas line L2: Argon (flow rate: 50 sccm) Substrate: Line & space pattern substrate with groove width of 50 nm, depth from surface of 1 μm, and aspect ratio of 20 Temperature of substrate: 200°C (when raw material gas is supplied and reaction gas is supplied) Total pressure of reaction chamber: 133 Pa (when raw material gas is supplied and reaction gas is supplied) Note that complete draw supply means supplying vaporized steam at room temperature to the reaction chamber 30 by reducing the pressure of the pump 50, without blowing gas into the raw material supply unit 10.

[0043] <Reaction Process> (1) With valve V1 and variable flow valve V2 open and valve V3 closed, exhaust pump 50 is used to exhaust the raw material, which has been vaporized at room temperature, from the raw material supply unit 10. The flow rate is adjusted by the mass flow controller M4 and supplied to the reaction chamber 30 through the raw material gas supply line L4 and the raw material gas purge line L3, allowing it to adhere to the surface of the substrate for 2 seconds. (2) After closing valve V1 and the mass flow controller M4 to stop the supply of raw material, the variable flow valve V2 is closed and valve V3 is opened, and the inside of the reaction chamber 30 is exhausted by the exhaust pump 50 for 1 second. (3) Argon is supplied from the carrier / dilution gas supply unit 40 to the reaction chamber 30 through the raw material gas purge line L3 for 5 seconds to purge the unreacted raw material in the reaction chamber 30 and exhaust it from the reaction chamber 30 through the exhaust line L6, while also adjusting the pressure in 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 by the mass flow controller M3. (4) With the pressure adjusted using the variable flow valve V2, the reaction gas with adjusted flow rate is supplied into the reaction chamber 30 for 3 seconds from the reaction gas supply unit 20 through the mass flow controller M5, the reaction gas supply line L5 and the reaction gas purge line L1, reacting 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 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 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 the first region, second region, and third region in the direction of the groove depth, starting 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 on the inner surface of the groove at a depth of 950 nm from the substrate surface, it grew with a thickness of d = 9.1 nm. From these thicknesses, the step coverage rate due to 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 rate = 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 by AFM, and Rms was 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). The cross-sectional TEM image is shown divided into a first region, a second region and a third region in the groove depth direction from the surface side, as in Example 1. From Figure 2(b), it was confirmed that aluminum oxide grew on the surface of the substrate with a film 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 surface of the substrate with a film 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 by AFM, and Rms was 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). The cross-sectional TEM image is shown divided into a first region, a second region and a third region in the groove depth direction from the surface side, as in Example 1. From Figure 2(c), it was confirmed that aluminum oxide grew on the surface of the substrate with a film 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 surface of the substrate with a film 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 manufactured 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 Rms was 0.23 nm, confirming that a smooth film had been manufactured. 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). The cross-sectional TEM image is shown divided into a first region, a second region and a third region in the groove depth direction from the surface side, as in Example 1. From Figure 2(d), it was confirmed that aluminum oxide grew on the surface of the substrate with a film 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 surface of the substrate with a film 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 Rms was 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). The cross-sectional TEM image is shown divided into a first region, a second region, and a third region in the groove depth direction from the surface side, as in Example 1. From Figure 2(e), it was confirmed that aluminum oxide grew on the surface of the substrate with a film 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 surface of the substrate with a film 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) A ​​solution of the raw material composition to be analyzed, diluted approximately 30 times with an organic solvent, 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 B, Cr, and Fe content in the above raw material composition was calculated by measuring the B, Cr, and Fe in the aqueous layer of the hydrolysis solution using an Agilent 8900 ICP-MS (dielectric-coupled plasma mass spectrometry) instrument manufactured by Agilent, calculating the molar content of each metal atom, and then dividing by the mass (g) of the raw material composition. (Cl) The Cl content 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]

[0051]

[0052] From the above results, the step coverage ratio in Examples 1 to 3 was greater than that of Comparative Examples 1 to 2. This confirms that the aluminum oxide film forming raw material composition of this disclosure can improve step coverage by the aluminum oxide film even when forming an aluminum oxide film on the surface of a three-dimensional substrate.

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

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 any one of claims 1 to 3, 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 any one of claims 1 to 4, 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 any one of claims 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 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 or 7, wherein the reaction step is carried out using atomic layer deposition.

9. An aluminum oxide film obtained by the method for forming an aluminum oxide film according to any one of claims 6 to 8.

10. An aluminum oxide film manufacturing apparatus comprising: a raw material supply unit for supplying the raw material composition for forming an aluminum oxide film according to any one of claims 1 to 5; a reaction gas supply unit for supplying a reaction gas containing an oxygen atom-containing gas; and a reaction chamber for reacting the raw material composition for forming an aluminum oxide film supplied from the raw material supply unit with the reaction gas supplied from the reaction gas supply unit.

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