Method for producing ruthenium thin films or ruthenium compound thin films by chemical vapor deposition and ruthenium thin films or ruthenium compound thin films

Abstract

To provide a chemical vapor deposition process that makes it possible to form a high-quality ruthenium thin film or the like while suppressing the oxidation of a substrate.SOLUTION: The present invention relates to a method for producing a ruthenium thin film or a ruthenium compound thin film by a chemical vapor deposition process, where the ruthenium thin film or the ruthenium compound thin film is formed by reacting an organic ruthenium compound with a reaction gas on a substrate. According to the present invention, the chemical vapor deposition process comprises: a first film formation step for using a non-oxidizing gas as a reaction gas; and a second film formation step for forming a film by using an oxidizing gas as a reaction gas after forming the film in the first film formation step. In addition, as the organic ruthenium compound serving as a precursor, any one among predetermined organic ruthenium compounds α, β, and γ containing a carbonyl ligand is used.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a ruthenium thin film or a ruthenium compound thin film by chemical vapor deposition (chemical vapor deposition (CVD) method, atomic layer deposition (ALD) method). More specifically, the present invention relates to a chemical vapor deposition method using a predetermined organic ruthenium compound, which aims to reduce the resistance of the thin film and achieve excellent film formation efficiency. [Background technology]

[0002] Thin films made of ruthenium or ruthenium compounds (hereinafter referred to as "ruthenium thin films, etc." or simply "thin films") are expected to be used as wiring and electrode materials for semiconductor devices such as DRAM and FERAM. This trend has become more pronounced with the miniaturization of wiring accompanying the recent miniaturization of semiconductor devices. Until now, copper has been the main material used for wiring in semiconductor devices, but in the wiring of fine semiconductor devices of the 10nm class, the wiring width is smaller than the mean free path of electrons in copper (approximately 38.7nm). Therefore, when copper thin films are applied to such fine wiring, the resistivity coefficient due to surface scattering and grain boundary scattering, which are proportional to the mean free path, increases, and the resistance value (specific resistivity) of the wiring rises. In contrast, the mean free path of electrons in ruthenium is 10.8nm, which is much shorter than that of copper, so the increase in specific resistivity due to surface scattering and grain boundary scattering can be suppressed. Furthermore, ruthenium is a high-melting-point metal with a higher melting point (2250°C) than copper (1085°C), and possesses high resistance to electromigration. Therefore, ruthenium as a wiring material offers many advantages, including the potential to reduce the resistance of fine wiring and extend the lifespan of the wiring.

[0003] Chemical vapor deposition (CVD) and atomic layer deposition (ALD) methods are used to manufacture ruthenium thin films and the like. As semiconductor devices become increasingly miniaturized, ruthenium thin films that make up the wiring and electrodes require a dense structure with a high aspect ratio. The ALD method is particularly useful for controlling the microstructure of such thin films. Many organic ruthenium compounds have been known to be used as precursors for manufacturing ruthenium thin films and the like by chemical vapor deposition.

[0004] Organic ruthenium compounds used as precursors have a significant impact on the properties of ruthenium thin films and the efficiency of film formation, and therefore, there are many studies on their use. Furthermore, the properties required of organic ruthenium compounds are diverse. In the past, in order to improve handling and lower the film formation temperature, factors such as being liquid at room temperature and having a high vapor pressure were the main considerations, and organic ruthenium compounds that address these issues have become known. For example, there is bis(ethylcyclopentadienyl)ruthenium(II) shown in Chemical Formula 1 described in Patent Document 1.

[0005] [ka]

[0006] Furthermore, in recent years, there has been a demand for expanding the range of reaction gases that can be used for the precursor organic ruthenium compounds. In chemical vapor deposition, it is common practice to introduce the reaction gas into the reactor along with the vaporized organic ruthenium compound. While it is possible to decompose organic ruthenium compounds by heating alone to deposit ruthenium thin films, this method results in a slow decomposition rate and inefficient film formation. Therefore, a reaction gas is introduced to accelerate the decomposition of the organic ruthenium compound. Older organic ruthenium compounds such as bis(ethylcyclopentadienyl)ruthenium(II) mentioned above require oxidizing gases such as oxygen or ozone as the reaction gas. However, oxidizing gases can cause oxidative damage to the substrate. While there are various substrate materials, Cu, W, and TiN, in particular, are relatively easy to oxidize. Oxidative damage to the substrate is undesirable in itself, but the resulting oxides can also degrade the properties of the thin film.

[0007] Therefore, recent requirements for precursors include the application of organic ruthenium compounds that can decompose non-oxidizing gases such as hydrogen and ammonia as reaction gases. The applicant has developed several organic ruthenium compounds that can meet these requirements. For example, Patent Document 2 contains dicarbonyl-bis(5-methyl-2,4-hexanediketonato)ruthenium(II) shown in Chemical Formula 2 below, and Patent Document 3 contains, as an example, hexacarbonyl[μ-[(1,2-η)-3-methyl-N-(1-methylpropyl)-1-butene-1-aminato-κC shown in Chemical Formula 3 below 2 κN 1 :κN 1 Zirthenium (Ru-Ru) is also mentioned, and further, Patent Documents 4 and 5 provide an example of the following chemical formula 3 (η 4 (-methylene-1,3-propanediyl)tricarbonylruthenium is listed.

[0008] [ka]

[0009] [ka]

[0010] [ka] [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2000-281694 [Patent Document 2] Patent No. 4746141 specification [Patent Document 3] Patent No. 6027657 specification [Patent Document 4] International Publication No. WO2021 / 153639 [Patent Document 5] Japanese Patent Publication No. 2020-090689 [Overview of the project] [Problems that the invention aims to solve]

[0012] The organic ruthenium compounds shown in Chemical Formulas 2 to 4 above allow for the deposition of ruthenium using a non-oxidizing gas such as hydrogen as the reaction gas, thereby suppressing oxidation of the substrate. However, according to the inventors' research, ruthenium thin films formed with these organic ruthenium compounds using a non-oxidizing gas may not have sufficiently reduced resistivity. In this regard, these organic ruthenium compounds can also be used for film formation with an oxidizing gas, and in some cases, ruthenium thin films formed with an oxidizing gas may have lower resistivity.

[0013] Furthermore, in the deposition of ruthenium thin films and other materials using non-oxidizing gases as the reaction gas, the deposition rate tends to be low. This is because non-oxidizing atmospheres, such as those containing hydrogen, are inherently less reactive. The organic ruthenium compounds shown in Chemical Formulas 2 to 5 above enable deposition using non-oxidizing gases such as hydrogen, which is an advantage compared to conventional organic ruthenium compounds. Compared to deposition in a highly reactive oxidizing gas atmosphere, non-oxidizing gases result in a lower deposition rate. If the goal is to achieve high-throughput thin film formation, improving the deposition rate is also important.

[0014] The present invention was made against the background described above. The present invention relates to a chemical vapor deposition method for depositing high-quality ruthenium thin films, etc., while suppressing oxidation of the substrate. To this end, the present invention aims to clarify the factors causing an increase in the resistivity of the thin film when an organic ruthenium compound that can be deposited using a non-oxidizing gas is used as the precursor organic ruthenium compound, and to propose a chemical vapor deposition method that avoids this increase. [Means for solving the problem]

[0015] To solve the above problems, the inventors first investigated the factors that cause high resistivity in ruthenium thin films deposited with non-oxidizing gases, and as a result, they concluded that the inclusion of impurity elements such as carbon (C) is the cause. Many of the organic ruthenium compounds that enable the deposition of ruthenium thin films in the aforementioned non-oxidizing gas atmosphere contain a carbonyl ligand (CO) as a ligand. Carbonyl ligands have high bonding affinity with ruthenium and are readily released as gas during the decomposition of organic ruthenium compounds, making them inherently suitable ligands. However, in a non-oxidizing gas atmosphere with low reactivity, the release of decomposition components from the reaction system is delayed, and these components may be introduced into the thin film as impurities. This is considered to be the cause of the increased resistivity of the thin film. In contrast, in an oxidizing gas atmosphere, due to its good reactivity, the decomposition components of the organic ruthenium compound are quickly released from the system, resulting in less impurity inclusion. However, as mentioned above, oxidizing gases can cause oxidation of the substrate.

[0016] Considering the effects of non-oxidizing and oxidizing gases on the substrate and thin film as described above, non-oxidizing gases are applicable when in contact with the substrate and are useful for depositing relatively thin films with little accumulation of impurities. On the other hand, oxidizing gases do not raise concerns about the accumulation of impurities, so if contact with the substrate can be avoided, they are suitable for securing a film deposition rate to obtain the desired film thickness. The inventors of the present invention have understood the suitability of each reaction gas as described above and have discovered a two-stage film deposition process by chemical vapor deposition to solve the above problems. This process involves first applying a non-oxidizing gas as the reaction gas in the initial stage of film deposition to deposit a ruthenium thin film or the like on the substrate, and then using an oxidizing gas as the reaction gas to grow the thin film. This led to the present invention.

[0017] In other words, the present invention relates to a method for producing a ruthenium thin film or a ruthenium compound thin film by chemical vapor deposition, in which an organic ruthenium compound reacts with a reaction gas on a substrate to form a ruthenium thin film or a ruthenium compound thin film, comprising: a first film formation step in which a non-oxidizing gas is introduced as the reaction gas and a ruthenium thin film or a ruthenium compound thin film is formed on the surface of the substrate; and a second film formation step in which, after the film formation in the first film formation step, an oxidizing gas is introduced as the reaction gas and a ruthenium thin film or a ruthenium compound thin film is formed, characterized in that any of the following organic ruthenium compounds α, β, and γ are used as the organic ruthenium compound introduced in the first and second film formation steps.

[0018] (1) Organoruthenium compound α [ka] (In the formula, ligand L1 is a linear or branched chain hydrocarbon group or cyclic hydrocarbon group having 2 to 13 carbon atoms. Ligand X is a carbonyl ligand (CO) or one of the isocyanide ligands (L2), pyridine ligands (L3), amine ligands (L4), imidazole ligands (L5), pyridazine ligands (L6), pyrimidine ligands (L7), or pyrazine ligands (L8) represented by formulas 6 to 12 below.)

[0019] [ka] (In the above formula, the substituent R1 of the isocyanide ligand L2 is one of the following: hydrogen, a linear or branched alkyl group having 1 to 8 carbon atoms, a cyclic alkyl group having 3 to 9 carbon atoms, a linear or branched amino group having 1 to 8 carbon atoms, an aryl group having 6 to 9 carbon atoms, a linear or branched alkoxy group having 1 to 8 carbon atoms, a linear or branched cyano group having 1 to 8 carbon atoms, a linear or branched nitro group having 1 to 8 carbon atoms, or a linear or branched fluoroalkyl group having 1 to 8 carbon atoms.)

[0020] [ka] (In the above formula, the substituents R2 to R6 of pyridine ligand L3 are, respectively, hydrogen, a linear or branched alkyl group or fluoroalkyl group having 1 to 5 carbon atoms, a linear or branched fluoro group having 1 to 5 carbon atoms, a linear or branched alkoxy group having 1 to 5 carbon atoms, a linear or branched cyano group having 1 to 5 carbon atoms, or a linear or branched nitro group having 1 to 5 carbon atoms.)

[0021] [ka] (In the above formula, substituents R7 to R9 of amine ligand L4 are each a linear or branched alkyl group having 1 to 5 carbon atoms.)

[0022] [ka] (In the above formula, the substituent R of the imidazole ligand L5) 10 is one of the following: hydrogen, a linear or branched alkyl group having 1 to 8 carbon atoms, a cyclic alkyl group having 3 to 8 carbon atoms, or a linear or branched fluoroalkyl group having 1 to 8 carbon atoms. Substituent R 11 ~R13 is each one of hydrogen, a linear or branched alkyl group having 1 to 5 carbon atoms, a linear or branched amino group having 1 to 5 carbon atoms, a linear or branched alkoxy group having 1 to 5 carbon atoms, a linear or branched cyano group having 1 to 5 carbon atoms, a linear or branched nitro group having 1 to 5 carbon atoms, a linear or branched fluoro group having 1 to 5 carbon atoms, or a linear or branched fluoroalkyl group having 1 to 5 carbon atoms.)

[0023]

Chemical formula

[0024]

Chemical formula

[0025]

Chemical formula

[0026] (2) Organoruthenium compound β [ka] (In the formula, R 26 , R 27 These elements may be identical or different, and each is either a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[0027] (3) Organoruthenium compound γ [ka] (In the formula, ligand L9 is the ligand represented by either (L9-1) or (L9-2) shown in the following formula, and is a ligand containing one nitrogen atom.)

[0028] [ka] (In the formula, * indicates the position of the atom that bridges and coordinates with ruthenium. 28 ~R 35 These elements may be identical or different, and each is either a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[0029] The method for producing ruthenium thin films, etc., by chemical vapor deposition according to the present invention, and the ruthenium thin films, etc., will be described in detail below.

[0030] A. Method for producing ruthenium thin films, etc., by chemical vapor deposition according to the present invention As described above, the method for depositing ruthenium thin films and the like according to the present invention has two film deposition steps with different reaction gases. In the following description, matters common to both film deposition steps will be explained, and then the first and second film deposition steps will be described.

[0031] (a) Basic process of chemical vapor deposition This invention relates to a method for forming ruthenium thin films and the like by chemical vapor deposition. Chemical vapor deposition is a method for producing thin films by introducing a raw material gas, which is a vaporized precursor consisting of an organic ruthenium compound, and a reaction gas onto the surface of a substrate, decomposing the organic ruthenium compound on the substrate, and depositing ruthenium or a ruthenium compound. Chemical vapor deposition is known to have two main types, depending on the supply of the raw material gas and reaction gas: chemical vapor deposition (CVD) and atomic layer deposition (ALD).

[0032] CVD is a film deposition method in which a raw material gas and a reaction gas are generally introduced onto a substrate simultaneously and reacted until a thin film of the desired thickness is formed. In contrast, ALD is a thin film formation process in which a series of steps constitute one cycle, and this cycle is repeated one or more times to achieve the desired thickness. These steps include introducing a raw material gas onto the substrate and adsorbing the raw material compound onto the substrate surface (adsorption step), exhausting excess raw material gas (raw material gas purging step), introducing a reaction gas and reacting the adsorbed raw material compound with the reaction gas on the substrate surface to form a thin film (reaction step), and further exhausting excess reaction gas (reaction gas purging step).

[0033] The chemical vapor deposition method of the present invention is applicable to both the CVD method and the ALD method. In the CVD method, a raw material gas and a non-oxidizing gas are introduced in the first film formation step, and a raw material gas and an oxidizing gas are introduced in the second film formation step. In the ALD method, in the first film formation step, the cycle consisting of the adsorption step, raw material gas purging step, reaction step with a non-oxidizing gas, and reaction gas purging step described above is repeated one or more times, and then in the second film formation step, the cycle consisting of the adsorption step, raw material gas purging step, reaction step with an oxidizing gas, and reaction gas purging step is repeated one or more times to obtain the desired film thickness.

[0034] Furthermore, in chemical vapor deposition, thermal CVD and thermal ALD methods are often used to heat the substrate or the like to promote the reaction between the raw material compound and the reaction gas, and the same is true in the present invention. In addition, in chemical vapor deposition, assistance by plasma (PECVD, PEALD) or lasers may be used in addition to heating, and these can also be applied to the first and / or second film formation steps in the present invention.

[0035] (b) substrate There are no particular limitations on the substrate used in this invention. In addition to Si substrates or Si / SiO2 substrates, substrates with thin films of Cu, W, TiN, etc. on their surface can be arbitrarily selected according to the specifications of the device to which they are used. In particular, since this invention is based on the premise of suppressing oxidation of the substrate, even substrates that are easily oxidized are not a problem.

[0036] (c) Organic ruthenium compounds (precursors) In this invention, the organic ruthenium compound used as a precursor is one that can form a ruthenium thin film or the like when a non-oxidizing gas is used as the reaction gas. If the precursor is not reactive with a non-oxidizing gas, film formation in the first film formation step becomes difficult, and the subsequent second film formation step cannot be performed. In this invention, the organic ruthenium compound α (Chemical Formula 5), ​​(2) organic ruthenium compound β (Chemical Formula 13), and (3) organic ruthenium compound γ (Chemical Formula 14) shown above are used as precursors. Each organic ruthenium compound will be described below.

[0037] (1) Organoruthenium compound α The organic ruthenium compound α is the organic ruthenium shown in formula 5 above. This organic ruthenium compound is a compound in which a linear or branched chain hydrocarbon group or a cyclic hydrocarbon group is coordinated as ligand L1 to ruthenium (divalent), and ligand X and two carbonyl ligands are further coordinated.

[0038] The ligand L1 of the organic ruthenium compound α is a linear or branched chain hydrocarbon group or cyclic hydrocarbon group having 2 to 13 carbon atoms, as described later, a trimethylene ligand (ligand L 10Examples include butadienyl ligands, pentadienyl ligands, hexadienyl ligands, and heptadienyl ligands.

[0039] On the other hand, the ligand X of the organoruthenium compound α can be any of the following: carbonyl ligand (CO), isocyanide ligand (L2), pyridine ligand (L3), amine ligand (L4), imidazole ligand (L5), pyridazine ligand (L6), pyrimidine ligand (L7), or pyrazine ligand (L8). The specific details of ligands L2 to L8 are as follows.

[0040] • Isocyanide ligand (L2) The isocyanide ligand (L2) is the ligand represented by the formula in formula 6 above. The substituent R1 of ligand L2 is hydrogen, a linear or branched alkyl group having 1 to 8 carbon atoms, a cyclic alkyl group having 3 to 9 carbon atoms, a linear or branched amino group having 1 to 8 carbon atoms, an aryl group having 6 to 9 carbon atoms, a linear or branched alkoxy group having 1 to 8 carbon atoms, a linear or branched cyano group having 1 to 8 carbon atoms, a linear or branched nitro group having 1 to 8 carbon atoms, or a linear or branched fluoroalkyl group having 1 to 8 carbon atoms. When ligand X is an isocyanide ligand, the substituent R1 of ligand L2 is preferably one of the following: a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a cyclohexyl group, a trifluoromethyl group, or a pentafluoroethyl group.

[0041] • Pyridine ligand (L3) The pyridine ligand (L3) is the ligand represented by the formula in Chemical Formula 7 above. The substituents R2 to R6 of ligand L3 are, each, hydrogen, a linear or branched alkyl or fluoroalkyl group having 1 to 5 carbon atoms, a linear or branched fluoro group having 1 to 5 carbon atoms, a linear or branched alkoxy group having 1 to 5 carbon atoms, a linear or branched cyano group having 1 to 5 carbon atoms, or a linear or branched nitro group having 1 to 5 carbon atoms. When ligand X is a pyridine ligand, it is preferable that all of R2 to R6 are hydrogen, or that R2, R4, and R6 are all methyl groups and R3 and R5 are hydrogen, or that R2, R3, R5, and R6 are all hydrogen and R4 is one of a methyl group, ethyl group, isopropyl group, tert-butyl group, trifluoromethyl group, methoxy group, cyano group, or nitro group.

[0042] • Amine ligand (L4) The amine ligand (L4) is the ligand represented by formula 8 above. The substituents R7 to R9 of ligand L4 are each a linear or branched alkyl group having 1 to 5 carbon atoms. When ligand X is an amine ligand, it is preferable that all of R7 to R9 are either a methyl group, an ethyl group, an n-propyl group, an isopropyl group, or an n-butyl group, or that R7 and R8 are both either a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, or a tert-butyl group, and R9 is hydrogen.

[0043] • Imidazole ligand (L5) The imidazole ligand (L5) is the ligand shown in formula 9 above. The substituent R of ligand L5 10 is one of the following: hydrogen, a linear or branched alkyl group having 1 to 8 carbon atoms, a cyclic alkyl group having 3 to 8 carbon atoms, or a linear or branched fluoroalkyl group having 1 to 8 carbon atoms. Substituent R 11 ~R 13Each of these is one of the following: hydrogen, a linear or branched alkyl group having 1 to 5 carbon atoms, hydrogen or a linear or branched amino group having 1 to 5 carbon atoms, hydrogen or a linear or branched alkoxy group having 1 to 5 carbon atoms, hydrogen or a linear or branched cyano group having 1 to 5 carbon atoms, hydrogen or a linear or branched nitro group having 1 to 5 carbon atoms, a linear or branched fluoro group having 1 to 5 carbon atoms, or hydrogen or a linear or branched fluoroalkyl group having 1 to 5 carbon atoms. When ligand X is an imidazole ligand, R 10 ~R 13 Is all of it hydrogen, or R 10 R is one of the following: methyl group, ethyl group, isopropyl group, tert-butyl group, or trifluoromethyl group. 11 ~R 13 R is either a hydrogen atom, a methyl group, or an ethyl group. 10 R is one of the following: a methyl group, an ethyl group, an isopropyl group, or a tert-butyl group or a trifluoromethyl group. 11 ~R 13 It is preferable that each of these is either a hydrogen atom, a methyl group, or an ethyl group.

[0044] • Pyridazine ligand (L6) The pyridazine ligand (L6) is the ligand shown in formula 10 above. The substituent R of ligand L6 14 ~R 17 Each of these is one of the following: hydrogen, a linear or branched alkyl group having 1 to 5 carbon atoms, a linear or branched fluoroalkyl group having 1 to 5 carbon atoms, a linear or branched fluoro group having 1 to 5 carbon atoms, hydrogen or a linear or branched alkoxy group having 1 to 5 carbon atoms, hydrogen or a linear or branched cyano group having 1 to 5 carbon atoms, or hydrogen or a linear or branched nitro group having 1 to 5 carbon atoms. When ligand X is a pyridazine ligand, R 14 ~R 17 Is all of it hydrogen, or R 14 R is one of the following: methyl group, ethyl group, isopropyl group, tert-butyl group, trifluoromethyl group, fluoro group, methoxy group, cyano group, or nitro group.15 ~R 17 R is either a hydrogen atom, a methyl group, or an ethyl group. 15 R is one of the following: a methyl group, an ethyl group, an isopropyl group, or a tert-butyl group. 14 and R 16 and R 17 Whether each of them is a hydrogen, methyl group, or ethyl group, R 15 and R 16 Both of these are methyl groups R 14 and R 17 It is preferable that either all of them are hydrogen, or either one of them is hydrogen.

[0045] • Pyrimidine ligand (L7) The pyrimidine ligand (L7) is the ligand shown in formula 11 above. The substituent R of ligand L7 18 ~R 21 Each of these is one of the following: hydrogen, a linear or branched alkyl group having 1 to 5 carbon atoms, a linear or branched fluoroalkyl group having 1 to 5 carbon atoms, a linear or branched fluoro group having 1 to 5 carbon atoms, hydrogen or a linear or branched alkoxy group having 1 to 5 carbon atoms, hydrogen or a linear or branched cyano group having 1 to 5 carbon atoms, or hydrogen or a linear or branched nitro group having 1 to 5 carbon atoms. When ligand X is a pyrimidine ligand, R 18 ~R 21 Is all of it hydrogen, or R 19 and R 20 and R 21 Both of these are methyl groups R 18 Is it hydrogen, or R 18 R is one of the following: methyl group, ethyl group, isopropyl group, tert-butyl group, trifluoro group, fluoro group, methoxy group, cyano group, or nitro group. 19 ~R 21 R is either a hydrogen atom, a methyl group, or an ethyl group. 20 R is one of the following: methyl group, ethyl group, isopropyl group, tert-butyl group, trifluoro group, fluoro group, methoxy group, cyano group, or nitro group. 18 and R 19 and R 21It is preferable that each of these is either a hydrogen atom, a methyl group, or an ethyl group.

[0046] • Pyrazine ligand (L8) The pyrazine ligand (L8) is the ligand shown in formula 12 above. The substituent R of ligand L8 22 ~R 25 Each of these is one of the following: hydrogen, a linear or branched alkyl group having 1 to 5 carbon atoms, a linear or branched fluoroalkyl group having 1 to 5 carbon atoms, a linear or branched fluoro group having 1 to 5 carbon atoms, hydrogen or a linear or branched alkoxy group having 1 to 5 carbon atoms, hydrogen or a linear or branched cyano group having 1 to 5 carbon atoms, or hydrogen or a linear or branched nitro group having 1 to 5 carbon atoms. When ligand X is a pyrazine ligand, R 22 ~R 25 Is all of it hydrogen, or R 22 R is one of the following: methyl group, ethyl group, isopropyl group, tert-butyl group, trifluoromethyl group, fluoro group, methoxy group, cyano group, or nitro group. 23 ~R 25 R is either a hydrogen atom, a methyl group, or an ethyl group. 23 R is one of the following: methyl group, ethyl group, isopropyl group, tert-butyl group, trifluoromethyl group, fluoro group, methoxy group, cyano group, or nitro group. 22 and R 24 and R 25 It is preferable that each of these is either a hydrogen atom, a methyl group, or an ethyl group.

[0047] Regarding the above-mentioned combination of ligand L1 and ligand X, an example of an organoruthenium compound α for which the present invention is useful is the following organoruthenium compound in which ligand L1 is a trimethylenemethane ligand and ligand X is carbonyl coordinated (i.e., three carbonyl ligands are coordinated).

[0048] [ka]

[0049] [ka]

[0050] In this organic ruthenium compound, trimethylene methane ligand L 10 The substituent R is hydrogen, or a linear or branched alkyl group having 1 to 8 carbon atoms, a cyclic alkyl group having 3 to 9 carbon atoms, a linear or branched alkenyl group having 2 to 8 carbon atoms, a linear or branched alkynyl group having 2 to 8 carbon atoms, a linear or branched amino group having 2 to 8 carbon atoms, or an aryl group having 6 to 9 carbon atoms. More preferably, the substituent R is hydrogen, a linear or branched alkyl group having 2 to 4 carbon atoms, a cyclic alkyl group having 5 to 8 carbon atoms, a linear or branched alkenyl group having 3 to 5 carbon atoms, a linear or branched alkynyl group having 3 to 5 carbon atoms, a linear or branched amino group having 3 to 5 carbon atoms, or an aryl group having 6 to 8 carbon atoms.

[0051] Ligand L 10The substituent R is preferably hydrogen, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group (2-methylpropyl), sec-butyl group (1-methylpropyl), tert-butyl group (1,1-dimethylethyl), n-pentyl group, isopentyl group (3-methylbutyl), neopentyl group (2,2-dimethylpropyl), sec-pentyl group (1-methylbutyl), tert-pentyl group (1,1-dimethylpropyl), n-hexyl group, isohexyl group (4-methylpentyl), neohexyl group (2,2-dimethylbutyl), sec-hexyl group (1-methylpentyl), tert-hexyl group (1,1-dimethylpentyl), cyclohexyl group, cyclohexylmethanyl group, or phenyl group. More preferably, the group is an ethyl group, an n-propyl group, an n-butyl group, an isobutyl group (2-methylpropyl), an n-pentyl group, an isopentyl group (3-methylbutyl), or a neopentyl group (2,2-dimethylpropyl).

[0052] (2) Organoruthenium compound β The organic ruthenium compound β is the organic ruthenium shown in formula 13 above. This organic ruthenium compound is an organic ruthenium compound in which two β-diketone ligands and two carbonyl ligands are coordinated to ruthenium.

[0053] substituent R of the β-diketone ligand 26 , R 27 R is hydrogen or an alkyl group having 1 to 4 carbon atoms. 26 , R 27 These may be the same or different from each other, but are preferably asymmetric γ-diketones that are different from each other. Furthermore, R 26 The number of carbon atoms and R 27 The total number of carbon atoms, including the number of carbon atoms, should be between 2 and 5.

[0054] (3) Organoruthenium compound γ The organoruthenium compound γ is the organoruthenium represented by Chemical Formula 14 above. This organoruthenium compound is a dinuclear organoruthenium compound having two metal-bonded rutheniums as central metals and, as ligands, a ligand L9 bridged to ruthenium and a carbonyl ligand. The ligand L9 is a monoimine containing one nitrogen atom and is either one of the two ligands (L9-1) or (L9-2) shown in Chemical Formula 16 above. Note that "bridged coordination" means that a single ligand coordinates in a three-dimensional manner so as to bridge two rutheniums. Specifically, among the above-described ligands (L9-1, L9-2), coordination to each ruthenium at the two positions indicated by * results in (a single ligand bridging two rutheniums) bridged coordination.

[0055] Substituents R of ligand L9 28 ~R 35 For, in L9-1, it is preferable that the total number of carbon atoms of each of the substituents R 28 ~R 30 is 3 or more and 10 or less. Also, in L9-2, it is preferable that the total number of carbon atoms of each of the substituents R 31 ~R 35 is 2 or more and 10 or less. Each substituent R 28 ~R 35 may be the same as or different from each other and is each any one of a hydrogen atom and an alkyl group having 1 to 4 carbon atoms. When the substituent R 28 ~R 35 is an alkyl group, it may be either linear or branched. The alkyl group is preferably any one of a methyl group, an ethyl group, a propyl group, or a butyl group.

[0056] Substituents R of ligand L9-1 28 ~R 30may be the same as or different from each other, and at least one of them is preferably any one of an ethyl group, a propyl group or a butyl group. R1 and R3 are also preferably branched alkyl groups. Specifically, as suitable substituents, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a sec-butyl group, or a tert-butyl group, etc. can be applied, and preferably, an ethyl group, an iso-propyl group, an iso-butyl group, a sec-butyl group, or a tert-butyl group.

[0057] R 29 is preferably either a hydrogen atom or a methyl group, and particularly preferably a hydrogen atom. These substituents R 29 are located in a three-dimensional direction with respect to the plane on which ruthenium is metallically bonded when the ligand L9 is bridged to ruthenium. When this substituent has a low carbon number, a complex that can be stably vaporized is easily obtained.

[0058] For the substituents R of the ligand L9-2 31 ~R 35 suitable substituents are, for R 31 preferably any one of an ethyl group, a propyl group or a butyl group. R 31 is also preferably a branched alkyl group. Specifically, as suitable substituents, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a sec-butyl group, or a tert-butyl group, etc. can be applied, and preferably, an ethyl group, an iso-propyl group, an iso-butyl group, a sec-butyl group, or a tert-butyl group. Also, R 32 R 33 R 34 and R 35 may be the same as or different from each other, and each is preferably either a hydrogen atom or a methyl group, and particularly preferably a hydrogen atom.

[0059] The organoruthenium compounds α, β, and γ of (1) to (3) serving as the precursors described above can be used as they are or by heating a solution dissolved in an appropriate solvent to obtain a raw material gas.

[0060] (I) First film formation process The first film deposition process involves depositing a ruthenium thin film or the like on a substrate using the aforementioned organic ruthenium compounds α, β, and γ as precursors and a non-oxidizing gas as the reaction gas. This film deposition process is an initial stage in which a thin film that forms the basis for the ruthenium thin film or the like, which is the target of the manufacturing process, is deposited while suppressing oxidation of the substrate.

[0061] The non-oxidizing gas that becomes the reaction gas in the first film formation step is a gas other than an oxidizing gas. Here, an oxidizing gas is a gaseous substance that is more likely than air to cause or assist in the combustion of other substances by supplying oxygen, and more specifically, a gaseous substance that falls under category 1 of the GHS classification. In the present invention, preferred non-oxidizing gases include hydrogen, water vapor, ammonia, amine compounds, hydrazine derivatives, and the like.

[0062] Furthermore, the amine compounds are represented as "R-NH2", "RR'-NH", and "RR'R"-N", where the substituents R, R', and R'' are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl (2-methylpropyl), sec-butyl (1-methylpropyl), tert-butyl (1,1-dimethylethyl), n-pentyl, isopentyl (3-methylbutyl), neopentyl (2,2-dimethylpropyl), and sec-pentyl (1- The group is selected from the group consisting of methylbutyl, tert-pentyl group (1,1-dimethylpropyl), n-hexyl group, isohexyl group (4-methylpentyl), neohexyl group (2,2-dimethylbutyl), sec-hexyl group (1-methylpentyl), tert-hexyl group (1,1-dimethylpentyl), cyclohexyl group, cyclohexylmethyl group, cyclohexylethyl group, phenyl group, and benzyl group. R, R', and R'' may be the same or different. R, R', and R'' are more preferably selected from the group consisting of methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group (2-methylpropyl), sec-butyl group (1-methylpropyl), tert-butyl group (1,1-dimethylethyl), n-pentyl group, isopentyl group (3-methylbutyl), neopentyl group (2,2-dimethylpropyl), sec-pentyl group (1-methylbutyl), and tert-pentyl group (1,1-dimethylpropyl).

[0063] Furthermore, the hydrazine derivative is a compound represented as "H2N-NRR'", where the substituents R and R' in the formula are selected from the group consisting of hydrogen, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group (2-methylpropyl), sec-butyl group (1-methylpropyl), tert-butyl group (1,1-dimethylethyl), n-pentyl group, isopentyl group (3-methylbutyl), neopentyl group (2,2-dimethylpropyl), sec-pentyl group (1-methylbutyl), tert-pentyl group (1,1-dimethylpropyl), n-hexyl group, isohexyl group (4-methylpentyl), neohexyl group (2,2-dimethylbutyl), sec-hexyl group (1-methylpentyl), tert-hexyl group (1,1-dimethylpentyl), cyclohexyl group, cyclohexylmethyl group, cyclohexylethyl group, phenyl group, and benzyl group. R and R' may be the same or different. More preferably, R and R' are selected from the group consisting of hydrogen, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group (2-methylpropyl), sec-butyl group (1-methylpropyl), tert-butyl group (1,1-dimethylethyl), n-pentyl group, isopentyl group (3-methylbutyl), neopentyl group (2,2-dimethylpropyl), sec-pentyl group (1-methylbutyl), and tert-pentyl group (1,1-dimethylpropyl).

[0064] Furthermore, the thickness of the ruthenium thin film, etc., deposited in the first deposition step is preferably 2 nm to 5 nm. Ruthenium thin films, etc., formed with non-oxidizing gases tend to contain impurities such as carbon. Therefore, if the thickness at this stage is made excessively thick, the resistivity of the thin film after the second deposition step may increase. Also, if the ruthenium thin film, etc., deposited in the first deposition step is too thin, the substrate may oxidize in the subsequent second deposition step using an oxidizing gas.

[0065] The film deposition conditions in the first film deposition step are arbitrarily set according to the characteristics of the precursor organic ruthenium compounds α, β, and γ. All of the organic ruthenium compounds α, β, and γ have relatively high vapor pressures and can be easily vaporized to produce the raw material gas. The heating temperature for vaporizing the precursors to produce the raw material gas is preferably between 0°C and 80°C.

[0066] Furthermore, the film deposition temperature is preferably between 150°C and 400°C. Below 150°C, the decomposition reaction of the organoruthenium compound is difficult to proceed, slowing down the film deposition process. On the other hand, if the film deposition temperature exceeds 400°C, uniform film deposition becomes difficult, and there are concerns about damage to the substrate. The film deposition temperature is the surface temperature of the substrate, and is usually controlled by heating the substrate.

[0067] Furthermore, in the ALD method, as described above, it is assumed that the cycle consisting of an adsorption step, a raw material gas purging step, a reaction step, and a reaction gas purging step is repeated multiple times. In this case, in the second and subsequent cycles, ruthenium, etc., may be deposited on top of the ruthenium thin film, etc., deposited in the previous cycle. In this case, although the film is not directly deposited on the substrate in that cycle, this cycle is naturally within the scope of the first film deposition step. That is, as long as the reaction gas is a non-oxidizing gas, the second and subsequent cycles are also within the scope of the first film deposition step.

[0068] (II) Second film formation process The second film deposition step involves depositing a ruthenium thin film or the like formed in the first film deposition step using an oxidizing gas as the reaction gas. This film deposition step differs from the first film deposition step only in the reaction gas used. Therefore, the second film deposition step can be performed in the same reactor as the first film deposition step.

[0069] The significance of the oxidizing gas that becomes the reaction gas in the second film formation step is as described above. In the present invention, suitable oxidizing gases include either oxygen or ozone.

[0070] The film deposition conditions in the second film deposition step can also be arbitrarily set according to the characteristics of the precursor organoruthenium compound. Furthermore, the heating temperature for vaporizing the precursor is preferably 0°C to 80°C, similar to the first film deposition step. The film deposition temperature during film deposition can be set while taking into account that the reaction gas is an oxidizing gas, but it can be within the same range as the first film deposition step. That is, the film deposition temperature is preferably 150°C to 400°C.

[0071] The second film deposition step is the process of depositing a ruthenium thin film or the like with the desired thickness. Therefore, the thickness of the ruthenium thin film or the like deposited in this step is not limited.

[0072] By going through the first and second film deposition steps described above, a ruthenium thin film of the desired thickness is deposited. There are no restrictions on the thickness of the ruthenium thin film deposited by the method according to the present invention. For example, when forming a thin ruthenium film of the 10 nm class (20 nm or less), compared to conventional film deposition using oxidizing gases, it is possible to suppress oxidation of the substrate and optimize the resistivity of the thin film. When the substrate is oxidized by an oxidizing gas, the thinner the film thickness, the more it is affected. By suppressing the oxidation of the substrate with the present invention, a thin film with lower resistance can be made. Furthermore, when increasing the film thickness, film deposition can be performed more efficiently than with conventional film deposition methods that use non-oxidizing gases as the reaction gas. This is because, after forming the base thin film in the first film deposition step, an oxidizing gas with excellent reactivity is used as the reaction gas.

[0073] B. Ruthenium thin film, etc., according to the present invention The present invention also presents ruthenium thin films or ruthenium compound thin films formed on a suitable substrate. The ruthenium thin films, etc., according to the present invention are oxygen-free on the substrate surface, and even when the film thickness is thin, the increase in resistance due to substrate oxidation is suppressed. That is, the present invention is a thin film made of ruthenium or a ruthenium compound formed on a substrate, wherein the thin film does not contain oxygen at the interface with the substrate.

[0074] Furthermore, the ruthenium thin film according to the present invention also has a reduced impurity content in the thin film. The organic ruthenium compounds described above contain ligands with carbon as a constituent element, such as carbonyl ligands, and there is a possibility that these ligands may be mixed into the thin film during film formation. The ruthenium thin film according to the present invention also suppresses the incorporation of impurities, and the resulting increase in resistance is also suppressed. In the ruthenium thin film according to the present invention, the average carbon concentration near the outermost surface of the thin film is reduced. Specifically, regarding the suppression of impurities in the ruthenium thin film according to the present invention, the average carbon concentration in the range from 10 nm to 25 nm from the outermost surface of the thin film is reduced to 0.05 atomic percent or less.

[0075] However, trace amounts of carbon may be present at the interface between the substrate and the thin film due to film formation using non-oxidizing gases. These trace amounts of carbon are found at the substrate surface (the interface between the substrate and the thin film). Specifically, the average carbon concentration in the region from the substrate surface up to 10 nm may be between 0.2 atomic% and 0.5 atomic%. It is more preferable that the carbon concentration near the substrate surface is between 0.2 atomic% and 0.5 atomic% in the region from the substrate surface up to 5 nm. However, because this carbon is present in extremely small amounts and is located near the very surface of the substrate, its effect on the overall resistance of the thin film is minimal.

[0076] Furthermore, a structural feature of the ruthenium thin film and the like according to the present invention is the reduction of surface roughness. According to the inventors, when a film is deposited using a non-oxidizing gas, the nucleation delay is short, and there is a tendency to form a thin film with a smooth surface by forming fine crystals. In the present invention, a smooth thin film is formed in the initial stage, and then a film is deposited on top of it with an oxidizing gas, resulting in a lower surface roughness than a thin film formed with a non-oxidizing gas alone. Factors that affect the resistivity of a thin film include surface scattering, grain boundary scattering, and surface roughness, which are all interrelated. It is considered that the ruthenium thin film and the like according to the present invention achieves low resistance, particularly through the improvement of surface roughness. This reduction in the surface roughness of the thin film can contribute to lowering the resistance of thin films with small film thicknesses.

[0077] There are no limitations on the film thickness of the ruthenium thin film, etc., according to the present invention. However, since the oxidation of the substrate is suppressed, the ruthenium thin film, etc., according to the present invention is particularly useful for thin films with a film thickness of 20 nm or less that may be affected by substrate oxidation. [Effects of the Invention]

[0078] As described above, the method for producing ruthenium thin films, etc., by chemical vapor deposition according to the present invention consists of a two-step film formation process. The present invention makes it possible to efficiently form low-resistance ruthenium thin films, etc., by utilizing the advantages of both non-oxidizing and oxidizing gases. [Brief explanation of the drawing]

[0079] [Figure 1] This figure illustrates the manufacturing process of a ruthenium thin film, including a two-step film deposition process by the ALD method according to an embodiment of the present invention. [Figure 2] FE-SEM images of the ruthenium thin films of Example 1 and Example 2, manufactured according to the first embodiment. [Figure 3] GI-XRD diffraction patterns of ruthenium thin films of Examples 1 and 2 and Comparative Example 1, manufactured in the first embodiment. [Figure 4] This figure shows the compositional analysis results in the depth direction of the ruthenium thin films of Example 1 and Comparative Examples 1 and 2, which were manufactured according to the first embodiment. [Figure 5] A graph showing the resistivity of ruthenium thin films of Examples 1 and 2 and Comparative Examples 1 and 2, manufactured according to the first embodiment. [Figure 6] A graph showing the film thickness and resistivity of the ruthenium thin films of Example 3 and Comparative Example 3, which were manufactured according to the second embodiment. [Modes for carrying out the invention]

[0080] First Embodiment The best embodiment of the present invention will be described below. In this embodiment, the precursor organoruthenium compound is organoruthenium compound α, and ligand L1 is trimethylenemethane ligand (L10 (η) R = hydrogen, and ligand X is carbonyl coordinated. 4 Using methylene-1,3-propanediyl)tricarbonylruthenium (Chemical Formula 4), a ruthenium thin film was deposited by ALD (Advanced Laser Deposition) using hydrogen as the non-oxidizing reaction gas in the first deposition step and oxygen as the oxidizing reaction gas in the second deposition step. For comparison, a ruthenium thin film was also deposited using a conventional single-step method, where only oxygen or only hydrogen was used as the reaction gas.

[0081] It is a precursor (η 4 (-methylene-1,3-propanediyl)tricarbonylruthenium was synthesized as follows: 50.0 g (97.5 mmol) of tricarbonyl-dichlororuthenium dimer was suspended in 1700 ml of tetrahydrofuran, and 300 ml of tetrahydrofuran solution of 29.2 g (231.6 mmol) of 3-chloro-2-(chloromethyl)-1-propene was added. 19.7 g (800 mmol) of shaved magnesium was slowly added, and the mixture was reacted at room temperature for 3 hours. 5 mL of methanol was added to the reaction mixture to quench it, and the solvent was removed by vacuum distillation. The resulting residue was extracted three times with 30 mL of pentane, and the solvent was removed by vacuum distillation. The resulting oil was purified by sublimation to obtain 16.3 g (68.3 mmol) of the target product, a colorless liquid (yield 35%). The synthesis reaction of this organoruthenium compound is as follows.

[0082] [ka]

[0083] [Deposition of ruthenium thin films] Figure 1 shows the flow of the manufacturing process for a ruthenium thin film by the ALD method in this embodiment. As explained above, the film formation process by the ALD method consists of (i) an adsorption step in which a raw material gas is introduced into the substrate, (ii) a raw material gas purging step in which excess raw material gas is exhausted, (iii) a reaction step in which a reaction gas is introduced to form a thin film, and (iv) a reaction gas purging step in which excess reaction gas is exhausted. These steps constitute one cycle and are repeated until the target film thickness is achieved.

[0084] In this embodiment, a ruthenium thin film was deposited on a Si substrate (2 cm × 2 cm) having a TiN film (20 nm thick) on its surface. The deposition conditions in the first and second deposition steps were as follows.

[0085] (I) First film formation process (i) Raw material gas introduction process ·Raw material heating temperature: 10℃ Carrier gas: Nitrogen (50 sccm) • Setup time: 5 seconds (ii) Raw material gas purging process • Purge gas: Nitrogen (100 sccm) • Setup time: 20 seconds (iii) Reaction gas introduction process • Reaction gas: Hydrogen (50 sccm) • Setup time: 30 seconds (iv) Reaction gas purging process • Purge gas: Nitrogen (100 sccm) • Setup time: 10 seconds

[0086] (II) Second film formation process (i) Raw material gas introduction process ·Raw material heating temperature: 10℃ Carrier gas: Nitrogen (50 sccm) • Setup time: 10 seconds (ii) Raw material gas purging process • Purge gas: Nitrogen (100 sccm) • Setup time: 10 seconds (iii) Reaction gas introduction process • Reaction gas: Oxygen (50 sccm) • Setup time: 10 seconds (iv) Reaction gas purging process • Purge gas: Nitrogen (100 sccm) • Setup time: 10 seconds

[0087] In this embodiment, the thickness of the ruthenium thin film deposited in the first deposition step (reaction gas: hydrogen) was set to 2 nm (Example 1) and 4 nm (Example 2). Then, in the second deposition step (reaction gas: oxygen), the ruthenium thin film was deposited so that the final thickness was 40 nm (Example 1: 38 nm deposition, Example 2: 36 nm deposition).

[0088] Furthermore, as comparative examples, ruthenium thin films were deposited using a one-step ALD method with oxygen alone (Comparative Example 1) or hydrogen alone (Comparative Example 2) as the reaction gas. In these comparative examples, 40 nm ruthenium thin films were deposited by controlling the number of cycles under the same conditions as the first and second deposition steps described above.

[0089] Figure 2 shows cross-sectional images of the ruthenium thin films of Examples 1 and 2 of this embodiment, taken by FE-SEM (electrolytic emission scanning electron microscope). Figure 3 shows the XRD diffraction patterns obtained by GI-XRD (small-angle ingress X-ray diffraction) of the ruthenium thin films of Examples 1 and 2 and Comparative Example 1. Regarding the crystallinity of the ruthenium thin films, the ruthenium thin films produced by the two-step deposition method of this embodiment can be said to be equivalent to those produced by the conventional one-step deposition method. From the GI-XRD results, the grain size of each ruthenium thin film was calculated to be 29.3 nm for Example 1, 28.5 nm for Example 2, and 32.2 nm for Comparative Example 1. Examples 1 and 2, which were deposited with hydrogen in the first deposition step, have smaller grain sizes than Comparative Example 1, which was deposited with oxygen only. As mentioned above, since the nucleation delay is short in deposition with non-oxidizing gases, fine crystal grains are formed rapidly. It is thought that in Examples 1 and 2, the thin films grew on top of the fine ruthenium crystals formed in this way. Furthermore, when the surface roughness of Example 1 and Comparative Example 1 was observed using an atomic force microscope, it was confirmed that the surface roughness of Comparative Example 1 was 2.0 nm, while that of Example 1 was reduced to 1.8 nm.

[0090] Furthermore, Figure 4 shows the results of depth-direction compositional analysis by SIMS (Secondary Ion Mass Spectrometry) performed on the ruthenium thin films of Example 1, Comparative Example 1, and Comparative Example 2. In the ruthenium thin film of Comparative Example 2, which was deposited in one step using only hydrogen, the presence of carbon (C) was confirmed at the substrate interface and within the film. In the case of the ruthenium thin film of Comparative Example 2, which was deposited in one step using only oxygen, no such carbon content was confirmed within the film. In Example 1, no carbon content was observed in the film either. Furthermore, comparing Example 1 and Comparative Example 1, the presence of oxygen (O) at the substrate interface in Comparative Example 1 was confirmed to be slight. Referring to these results, it can be said that the two-step film deposition method using hydrogen and oxygen in Example 1 suppresses the incorporation of oxygen at the substrate interface (substrate oxidation) and the incorporation of carbon within the film, thereby enabling the production of high-purity ruthenium thin films.

[0091] Next, the resistivity of the ruthenium thin films of Examples 1 and 2 and Comparative Examples 1 and 2 was measured. The resistivity was measured using the four-probe method. The results of this measurement are shown in Figure 5. Among these ruthenium thin films, Comparative Example 2 had the highest resistivity. As mentioned above, the ruthenium thin film deposited with hydrogen, a non-oxidizing gas, contains impurities such as carbon, which is thought to have increased its resistivity. As a result, Comparative Example 1 is considered to have a higher resistivity than the ruthenium thin film deposited with oxygen in Comparative Example 1.

[0092] Compared to these comparative examples, the ruthenium thin film produced by the two-step deposition process in Example 1 has a lower resistivity than the ruthenium thin film produced by oxygen in Comparative Example 1. This can be attributed to the suppression of substrate oxidation by applying hydrogen in the first deposition process, and the rapid deposition reaction and impurity release by applying oxygen in the second deposition process, resulting in a lower resistivity for the thin film. In Example 2, the resistivity is higher than that of Comparative Example 1, but the difference is slight and at a comparable level. Considering that the application of a non-oxidizing gas in the first deposition process in Example 2 almost completely eliminates concerns about damage due to substrate oxidation, Example 2 can be said to have yielded good results, similar to Example 1. This evaluation of Example 2 is supported by the fact that this thin film had a clearly lower resistivity than the thin film of Comparative Example 2.

[0093] Second Embodiment In this embodiment, the change in resistivity when the thickness of the ruthenium thin film was increased while applying a two-stage film deposition process was investigated. Under the same conditions as in the first embodiment, a 2 nm ruthenium thin film was deposited in the first film deposition step (reaction gas: hydrogen), and a ruthenium thin film was deposited in the second film deposition step (reaction gas: oxygen). At this time, ruthenium thin films were deposited with final film thicknesses of 5 nm, 12 nm, 18 nm, and 23 nm in the second film deposition step (Example 3). The resistivity was then measured for each ruthenium thin film thickness.

[0094] Furthermore, as a comparative example to this Example 3, ruthenium thin films of 6 nm, 10 nm, 15 nm, and 20 nm were deposited in a one-step film deposition process using oxygen as the reaction gas, and their resistivity was measured (Comparative Example 3).

[0095] Figure 6 shows the resistivity measurement results for these ruthenium thin films. From Figure 6, it can be confirmed that the ruthenium thin film deposited in a two-step process (Example 3) has a resistivity equal to or lower than that of the ruthenium thin film deposited in a one-step process using oxygen as the reaction gas (Comparative Example 3). In particular, for thin films with a small thickness (12 nm or less), the thin film deposited in a two-step process has a lower resistivity. This is thought to be due to the suppression of substrate oxidation by applying a non-oxidizing gas in the first deposition step and the reduction of surface roughness due to the small particle size. Such low resistance of ultrathin ruthenium thin films is expected to be useful in thin-film electrodes for miniaturized semiconductor devices. [Industrial applicability]

[0096] As described above, the two-step film deposition process for manufacturing ruthenium thin films and the like according to the present invention can form high-quality, low-resistivity ruthenium thin films and the like while suppressing oxidation of the substrate. The present invention is suitable for use as wiring and electrode materials in semiconductor devices such as DRAMs. In particular, it can accommodate the miniaturization of wiring in ultra-miniature semiconductor devices.

Claims

1. In a method for producing a ruthenium thin film or a ruthenium compound thin film by chemical vapor deposition, in which an organic ruthenium compound and a reaction gas are reacted on a substrate to form a ruthenium thin film or a ruthenium compound thin film, A first film formation step involves introducing a non-oxidizing gas as the reaction gas and forming a ruthenium thin film or a ruthenium compound thin film on the substrate surface. The process includes a second film formation step in which, after the film formation step described above, an oxidizing gas is introduced as the reaction gas to form a ruthenium thin film or a ruthenium compound thin film, A method for producing a ruthenium thin film or a ruthenium compound thin film, characterized in that the organic ruthenium compound introduced in the first and second film formation steps is an organic ruthenium compound as shown in the following formula 1, in which ruthenium is coordinated with ligand L10, which is a trimethylene methane-based ligand as shown in formula 2 below, two carbonyl ligands (CO), and either a carbonyl ligand or ligands L2 to L8 as shown in formulas 3 to 9 below. 【Chemistry 1】 (In the formula, the ligand L １０ This is represented by the formula in equation 2 below. It is a trimethylenemethane ligand. Furthermore, ligand X is either a carbonyl ligand (CO) or an isocyanide ligand (L) represented by the following formulas 3 to 9. ２ ), pyridine ligand (L ３ ), amine ligand (L ４ ), imidazole ligand (L ５ ), pyridazine ligand (L ６ ), pyrimidine ligand (L ７ ), pyrazine ligand (L ８ It is one of the following: 【Chemistry 2】 (In the above formula, for the substituent R of the trimethylenemethane ligand L １０ is any one of hydrogen, a linear or branched alkyl group having 1 to 8 carbon atoms, a cyclic alkyl group having 3 to 9 carbon atoms, a linear or branched alkenyl group having 2 to 8 carbon atoms, a linear or branched alkynyl group having 2 to 8 carbon atoms, a linear or branched amino group having 2 to 8 carbon atoms, and an aryl group having 6 to 9 carbon atoms.) 【Transformation 3】 (In the above formula, isocyanide ligand L) ２ substituent R １ (This is one of the following: hydrogen, a linear or branched alkyl group having 1 to 8 carbon atoms, a cyclic alkyl group having 3 to 9 carbon atoms, a linear or branched amino group having 1 to 8 carbon atoms, an aryl group having 6 to 9 carbon atoms, a linear or branched alkoxy group having 1 to 8 carbon atoms, a linear or branched cyano group having 1 to 8 carbon atoms, a linear or branched nitro group having 1 to 8 carbon atoms, or a linear or branched fluoroalkyl group having 1 to 8 carbon atoms.) 【Chemistry 4】 (In the above formula, pyridine ligand L) ３ substituent R ２ ~R ６ Each of these is one of the following: hydrogen, a linear or branched alkyl group or fluoroalkyl group having 1 to 5 carbon atoms, a linear or branched fluoro group having 1 to 5 carbon atoms, a linear or branched alkoxy group having 1 to 5 carbon atoms, a linear or branched cyano group having 1 to 5 carbon atoms, or a linear or branched nitro group having 1 to 5 carbon atoms. 【Transformation 5】 (In the above formula, amine ligand L ４ substituent R ７ ~R ９ Each of these is a linear or branched alkyl group having 1 to 5 carbon atoms. 【Transformation 6】 (In the above formula, imidazole ligand L ５ substituent R １０ is one of the following: hydrogen, a linear or branched alkyl group having 1 to 8 carbon atoms, a cyclic alkyl group having 3 to 8 carbon atoms, or a linear or branched fluoroalkyl group having 1 to 8 carbon atoms. Substituent R １１ ~R １３ Each of these is one of the following: hydrogen, a linear or branched alkyl group having 1 to 5 carbon atoms, a linear or branched amino group having 1 to 5 carbon atoms, a linear or branched alkoxy group having 1 to 5 carbon atoms, a linear or branched cyano group having 1 to 5 carbon atoms, a linear or branched nitro group having 1 to 5 carbon atoms, a linear or branched fluoro group having 1 to 5 carbon atoms, or a linear or branched fluoroalkyl group having 1 to 5 carbon atoms. 【Transformation 7】 (In the above formula, pyridazine ligand L) ６ substituent R １４ ~R １７ Each of these is either hydrogen, a linear or branched alkyl group having 1 to 5 carbon atoms, a linear or branched fluoroalkyl group having 1 to 5 carbon atoms, a linear or branched fluoro group having 1 to 5 carbon atoms, hydrogen or a linear or branched alkoxy group having 1 to 5 carbon atoms, hydrogen or a linear or branched cyano group having 1 to 5 carbon atoms, or hydrogen or a linear or branched nitro group having 1 to 5 carbon atoms. 【Transformation 8】 (In the above formula, pyrimidine ligand L) ７ substituent R １８ ~R ２１ Each of these is either hydrogen, a linear or branched alkyl group having 1 to 5 carbon atoms, a linear or branched fluoroalkyl group having 1 to 5 carbon atoms, a linear or branched fluoro group having 1 to 5 carbon atoms, a linear or branched alkoxy group having 1 to 5 carbon atoms, a linear or branched cyano group having 1 to 5 carbon atoms, or a linear or branched nitro group having 1 to 5 carbon atoms. 【Chemistry 9】 (In the above formula, pyrazine ligand L ８ substituent R ２２ ~R ２５ Each of these is either hydrogen, a linear or branched alkyl group having 1 to 5 carbon atoms, a linear or branched fluoroalkyl group having 1 to 5 carbon atoms, a linear or branched fluoro group having 1 to 5 carbon atoms, a linear or branched alkoxy group having 1 to 5 carbon atoms, a linear or branched cyano group having 1 to 5 carbon atoms, or a linear or branched nitro group having 1 to 5 carbon atoms.

2. A method for producing a ruthenium thin film or a ruthenium compound thin film according to claim 1, wherein the non-oxidizing gas in the first film formation step is one of hydrogen, water vapor, ammonia, organic amines, or hydrazine derivatives.

3. A method for producing a ruthenium thin film or a ruthenium compound thin film according to claim 1 or claim 2, wherein the oxidizing gas in the second film formation step is either oxygen or ozone.

4. A method for producing a ruthenium thin film or a ruthenium compound thin film according to claim 1 or claim 2, wherein a ruthenium thin film or a ruthenium compound thin film is formed in a first film formation step with a film thickness in the range of 2 nm to 5 nm.

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