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

Abstract

The present invention relates to a method for producing a ruthenium thin film or a ruthenium compound thin film by a chemical vapor deposition method 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. This chemical vapor deposition method comprises a first film formation step in which a non-oxidizing gas is applied as a reaction gas, and a second film formation step in which a film is formed using an oxidizing gas as a reaction gas after being formed in the first film formation step. Furthermore, any one of predetermined organic ruthenium compounds alpha, beta, and gamma containing a carbonyl ligand is applied as the organic ruthenium compound that serves as the precursor. According to the chemical vapor deposition method of the present invention, it is possible to efficiently form a high-quality ruthenium thin film while suppressing oxidation of a substrate.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a ruthenium thin film or a ruthenium compound thin film by chemical vapor deposition (chemical vapor deposition (CVD) method, atomic layer deposition (ALD) method). Specifically, it relates to a chemical vapor deposition method using a predetermined organic ruthenium compound, which method achieves low resistance of the thin film and excellent film formation efficiency. Background Art

[0002] A thin film composed of ruthenium or a ruthenium compound (hereinafter referred to as "ruthenium thin film, etc." or simply "thin film") is expected to be used as a wiring / electrode material for semiconductor devices such as DRAM and FERAM. This trend has become more significant as the wiring has become smaller with the recent ultra-miniaturization of semiconductor devices. So far, copper has been mainly used as the wiring material for semiconductor elements, but in the wiring of fine semiconductor elements of the 10nm level, the wiring width is smaller than the mean free path of copper electrons (about 38.7nm). Therefore, when a copper thin film is applied to the fine wiring, the resistivity caused by surface scattering and grain boundary scattering proportional to the mean free path increases, and the resistance value (resistance) of the wiring increases. In contrast, the mean free path of ruthenium electrons is 10.8nm, which is very short compared to copper, so it is possible to suppress the increase in resistivity caused by surface scattering and grain boundary scattering. In addition, ruthenium is a high melting point metal with a higher melting point (melting point 2250°C) than copper (melting point 1085°C), and has high resistance to electromigration. Therefore, ruthenium as a wiring material can realize low resistance of fine wiring and can be expected to prolong the life of the wiring, and has many advantages.

[0003] As a manufacturing method for ruthenium thin films, chemical vapor deposition methods such as CVD (chemical vapor deposition) and ALD (atomic layer deposition) are used. In addition, ruthenium thin films that constitute the wiring / electrodes of semiconductor devices that are being miniaturized require dense structures with high aspect ratios. The ALD method is particularly useful for controlling the fine structure of such thin films. In addition, as raw materials (precursors) for manufacturing ruthenium thin films using chemical vapor deposition, many organic ruthenium compounds are known to date.

[0004] Organic ruthenium compounds as precursors have a great influence on the properties of ruthenium thin films and the efficiency of film formation, so there are many research examples. In addition, the properties required of organic ruthenium compounds also involve many aspects. In the past, due to the low temperature of operability and film formation temperature, liquid at room temperature or high vapor pressure became the subject of research, and organic ruthenium compounds corresponding to these topics are well known. For example, there is bis(ethylcyclopentadienyl)ruthenium (II) represented by chemical formula 1 recorded in patent document 1.

[0005] [Chemical formula 1]

[0006]

[0007] In addition, in recent years, for the organic ruthenium compound as a precursor, it is required to expand the selection range of the reaction gas. In the chemical vapor deposition method, the reaction gas is usually introduced into the reactor together with the organic ruthenium compound after gasification. The organic ruthenium compound can also precipitate the ruthenium film etc. only by heating and decomposing, but in this case, the decomposition rate is insufficient and effective film formation cannot be expected. Therefore, in order to promote the decomposition of the organic ruthenium compound, the reaction gas is introduced. The organic ruthenium compounds known to the public such as the above-mentioned bis (ethylcyclopentadienyl) ruthenium (II) need to use oxidizing gases such as oxygen or ozone as reaction gases. However, oxidizing gases become the main cause of oxidation damage to the substrate. Although there are various materials as the substrate, Cu, W, TiN, etc. are particularly easy to oxidize. Moreover, the damage itself caused by the oxidation of the substrate is not preferred, and the oxides generated sometimes also reduce the characteristics of the film.

[0008] Therefore, as a recent requirement for precursors, it is required to use an organic ruthenium compound that can be decomposed even when a non-oxidizing gas such as hydrogen or ammonia is used as a reaction gas. The applicant of the present application has developed a number of organic ruthenium compounds that can meet such requirements. For example, in Patent Document 2, the following chemical formula 2 of dicarbonyl-bis(5-methyl-2,4-hexanedione)ruthenium (II) is recorded, and in Patent Document 3, the following chemical formula 3 of hexacarbonyl [μ-[(1,2-η)-3-methyl-N-(1-methylpropyl)-1-butene-1-amine (aminato)- κ C 2 , κ N 1 : κ N 1 ]] ruthenium (Ru-Ru), and in Patent Documents 4 and 5, the following chemical formula 3 (η 4 -methylene-1,3-propanediyl)ruthenium tricarbonyl.

[0009] [Chemical formula 2]

[0010]

[0011] [Chemical formula 3]

[0012]

[0013] [Chemical formula 4]

[0014]

[0015] Prior art literature

[0016] Patent Literature

[0017] Patent Document 1: Japanese Patent Application Publication No. 2000-281694

[0018] Patent Document 2: Japanese Patent No. 4746141

[0019] Patent Document 3: Japanese Patent No. 6027657

[0020] Patent Document 4: International Publication No. WO2021 / 153639

[0021] Patent Document 5: Japanese Patent Application Publication No. 2020-090689 Summary of the invention

[0022] Problems to be solved by the invention

[0023] The organic ruthenium compounds of the above-mentioned chemical formulas 2 to 4 can precipitate ruthenium using non-oxidizing gases such as hydrogen as reaction gases, thereby inhibiting the oxidation of the substrate. However, according to the research of the present inventors, the specific resistance of the ruthenium thin film etc. formed by these organic ruthenium compounds using non-oxidizing gases is sometimes not sufficiently reduced. In this regard, these organic ruthenium compounds can also be formed into films using oxidizing gases, and depending on the circumstances, the ruthenium thin film etc. using oxidizing gases sometimes has a low resistance.

[0024] In addition, in the film formation of ruthenium thin films, etc. using non-oxidizing gases as reaction gases, the film formation rate tends to be low. This is because non-oxidizing atmospheres using hydrogen, etc. lack reactivity. The organic ruthenium compounds of the above chemical formulas 2 to 5 can be formed into films using non-oxidizing gases such as hydrogen, which is an advantage compared to conventional organic ruthenium compounds, etc. Compared with film formation in a highly reactive oxidizing gas atmosphere, the film formation rate of non-oxidizing gases is poor. If the goal is to achieve high throughput of thin film formation, improvement in the film formation rate is also important.

[0025] The present invention was completed in view of the above background. The present invention relates to a chemical vapor deposition method for forming a high-quality ruthenium thin film or the like while suppressing oxidation of a substrate. In this purpose, the present invention proposes a chemical vapor deposition method that clarifies the main cause of the increase in the resistivity of the thin film when an organic ruthenium compound that can be formed into a film using a non-oxidizing gas is used as an organic ruthenium compound as a precursor, and avoids the increase in the resistivity of the thin film.

[0026] Means for solving problems

[0027] In order to solve the above-mentioned problems, the inventors first studied the main reason for the increase in the specific resistance of ruthenium thin films, etc., which are formed by non-oxidizing gases, and the mixing of impurity elements such as carbon (C) was thought of. Most of the organic ruthenium compounds that can form ruthenium thin films, etc. in the above-mentioned non-oxidizing gas atmosphere contain carbonyl ligands (CO) as ligands. Carbonyl ligands have high binding properties with ruthenium, and on the other hand, they are easily released in the form of gas when the organic ruthenium compound decomposes, so they are originally suitable ligands. However, in a non-oxidizing gas atmosphere with low reactivity, the release of decomposed components from the reaction system is sometimes delayed and mixed into the film in the form of impurities. According to investigations, this is the main reason for the increase in the specific resistance of the film. In contrast, in an oxidizing gas atmosphere, due to its good reactivity, the decomposed components of the organic ruthenium compound are quickly released outside the system, and the mixing of impurities is small. However, as mentioned above, oxidizing gases may become the main cause of substrate oxidation.

[0028] When the effects of non-oxidizing gas and oxidizing gas on substrates and thin films are understood as described above, it is believed that non-oxidizing gas can be used in contact with the substrate, which is useful for forming thinner thin films with less impurity accumulation. On the other hand, since there is less concern about impurity accumulation in oxidizing gas, if contact with the substrate can be avoided, it is suitable for ensuring a film formation speed for obtaining a desired film thickness. The inventors understood the appropriateness of each reaction gas as described above, and as a film formation method using chemical vapor deposition to solve the above-mentioned problems, discovered a two-stage film formation process: after using non-oxidizing gas as a reaction gas in the initial stage of film formation to form a ruthenium thin film or the like on a substrate, an oxidizing gas is used as a reaction gas to grow the thin film, thereby conceiving of the present invention.

[0029] That is, the present invention is a method for manufacturing a ruthenium thin film or a ruthenium compound thin film, which is a method for manufacturing a ruthenium thin film or a ruthenium compound thin film by a chemical vapor deposition method 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, comprising: a first film-forming step, in which a non-oxidizing gas is introduced as the reaction gas to form a ruthenium thin film or a ruthenium compound thin film on the surface of the substrate; and a second film-forming step, in which, after the film is formed by the first film-forming step, an oxidizing gas is introduced as the reaction gas to form a ruthenium thin film or a ruthenium compound thin film, and as the organic ruthenium compound introduced in the first film-forming step and the second film-forming step, any one of the organic ruthenium compounds α, β, γ described in the following (1) to (3) is used.

[0030] (1)Organorthenium compounds α

[0031] [Chemical formula 5]

[0032] L1Ru(CO)2X

[0033] (In the formula, the ligand L1 is a linear or branched hydrocarbon group or a cyclic hydrocarbon group having 2 to 13 carbon atoms. In addition, the ligand X is a carbonyl ligand (CO) or any one of an isonitrile ligand (L2), a pyridine ligand (L3), an amine ligand (L4), an imidazole ligand (L5), a pyridazine ligand (L6), a pyrimidine ligand (L7), and a pyrazine ligand (L8) represented by the following chemical formula 6 to chemical formula 12.)

[0034] [Chemical formula 6]

[0035]

[0036] (In the above formula, the substituent R1 of the isonitrile ligand L2 is any one of the following groups: hydrogen, a linear or branched alkyl group having 1 to 8 carbon atoms, or 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.)

[0037] [Chemical formula 7]

[0038]

[0039] (In the above formula, the substituents R2 to R6 of the pyridine ligand L3 are each any one of the following groups: 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, and a linear or branched nitro group having 1 to 5 carbon atoms.)

[0040] [Chemical formula 8]

[0041]

[0042] (In the above formula, the substituents R7 to R9 of the amine ligand L4 are each a linear or branched alkyl group having 1 to 5 carbon atoms.)

[0043] [Chemical formula 9]

[0044]

[0045] (In the above formula, the substituent R of the imidazole ligand L5 10is any one of the following groups: 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. 11 ~R 13 Each is any one of the following groups: 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, and a linear or branched fluoroalkyl group having 1 to 5 carbon atoms.)

[0046] [Chemical formula 10]

[0047]

[0048] (In the above formula, the substituent R of the pyridazine ligand L6 14 ~R 17 Each is any one of the following groups: 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, hydrogen or a linear or branched nitro group having 1 to 5 carbon atoms.)

[0049] [Chemical formula 11]

[0050]

[0051] (In the above formula, the substituent R of the pyrimidine ligand L7 18 ~R 21 Each is any one of the following groups: 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, and a linear or branched nitro group having 1 to 5 carbon atoms.)

[0052] [Chemical formula 12]

[0053]

[0054] (In the above formula, the substituent R of the pyrazine ligand L8 22 ~R 25Each is any one of the following groups: 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, and a linear or branched nitro group having 1 to 5 carbon atoms.)

[0055] (2)Organoruthenium compounds β

[0056] [Chemical formula 13]

[0057]

[0058] (Where R 26 , R 27 They may be the same or different from each other, and each is any one of a hydrogen atom and an alkyl group having 1 to 4 carbon atoms.)

[0059] (3)Organoruthenium compounds γ

[0060] [Chemical formula 14]

[0061]

[0062] (In the formula, the ligand L9 is a ligand represented by any one of the following formulas (L9-1) or (L9-2), and is a ligand containing one nitrogen atom.)

[0063] [Chemical formula 15]

[0064]

[0065] (where * is the position of the atom that is bridged and coordinated with ruthenium. R 28 ~R 35 They may be the same or different from each other, and each is any one of a hydrogen atom and an alkyl group having 1 to 4 carbon atoms.)

[0066] Hereinafter, a method for producing a ruthenium thin film or the like by chemical vapor deposition and the ruthenium thin film or the like according to the present invention will be described in detail.

[0067] A. Method for producing ruthenium thin film etc. by chemical vapor deposition method according to the present invention

[0068] As described above, the film forming method of the ruthenium thin film etc. according to the present invention has two-stage film forming processes with different reaction gases. In the following description, the matters common to the two film forming processes are described, and on this basis, the first and second film forming processes are described.

[0069] (a) Basic process of chemical vapor deposition

[0070] The present invention is a method for forming a ruthenium thin film or the like by chemical vapor deposition. The chemical vapor deposition method is a method in which a raw material gas and a reaction gas formed by vaporizing a precursor composed of an organic ruthenium compound are introduced to a substrate surface, and the organic ruthenium compound is decomposed on the substrate to precipitate / deposit ruthenium or a ruthenium compound, thereby manufacturing a thin film. The chemical vapor deposition method is known to include a chemical vapor deposition method (CVD method) and an atomic layer deposition method (ALD method) depending on the supply of the raw material gas and the reaction gas.

[0071] The CVD method is a film forming method that generally introduces a raw material gas and a reaction gas onto a substrate at the same time and reacts them until a thin film of a desired film thickness is formed. In contrast, the ALD method is a process of introducing a raw material gas onto a substrate and allowing the raw material compound to adsorb onto the substrate surface (adsorption process), exhausting the remaining raw material gas (raw material gas purging process), introducing a reaction gas and allowing the raw material compound adsorbed onto the substrate surface to react with the reaction gas on the surface to form a thin film (reaction process), and further exhausting the remaining reaction gas (reaction gas purging process). This series of steps is considered as one cycle, and the cycle is repeated one or more times to form a thin film forming process of a desired film thickness.

[0072] The chemical vapor deposition method of the present invention can be applied 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 forming step, and a raw material gas and an oxidizing gas are introduced in the second film forming step. In addition, in the ALD method, in the first film forming step, a cycle consisting of the above-mentioned adsorption step / raw material gas purge step / non-oxidizing gas reaction step / reactive gas purge step is repeated one or more times, and then, in the second film forming step, a cycle consisting of the adsorption step / raw material gas purge step / oxidizing gas reaction step / reactive gas purge step is repeated one or more times, thereby achieving a desired film thickness.

[0073] In addition, in the chemical vapor deposition method, in order to promote the reaction between the raw material compound and the reaction gas, a thermal CVD method or a thermal ALD method that heats the substrate is often used, and the same is true for the present invention. In addition, in the chemical vapor deposition method, in addition to assisting by heating, it can also be assisted by plasma (PECVD, PEALD) or laser, but in the present invention, they can also be applied to the first film forming step and / or the second film forming step.

[0074] (b)Substrate

[0075] The substrate of the present invention is not particularly limited. The material can be arbitrarily selected from Si substrates or Si / SiO2 substrates, and other substrates having a thin film of Cu, W, TiN, etc. on the surface, according to the specifications of the device to which it is applied. In particular, the present invention is based on the premise of suppressing the oxidation of the substrate, so there is no problem even if the substrate is easily oxidized.

[0076] (c) Organic ruthenium compounds (precursors)

[0077] In the present invention, the organic ruthenium compound used as a precursor is a compound that can form a ruthenium thin film or the like when a non-oxidizing gas is used as a reaction gas. This is because the precursor that is not reactive to the non-oxidizing gas makes it difficult to form a film in the first film forming step, and the subsequent second film forming step cannot be performed. Therefore, in the present invention, the above-mentioned (1) organic ruthenium compound α (chemical formula 5), ​​(2) organic ruthenium compound β (chemical formula 13), and (3) organic ruthenium compound γ (chemical formula 14) are used as precursors. The following describes each organic ruthenium compound.

[0078] (1)Organorthenium compounds α

[0079] The organic ruthenium compound α is an organic ruthenium represented by the above chemical formula 5. The organic ruthenium compound is a compound in which a linear or branched chain hydrocarbon group or a cyclic hydrocarbon group is coordinated to ruthenium (divalent) as a ligand L1, and a ligand X and two carbonyl ligands are also coordinated.

[0080] The ligand L1 of the organic ruthenium compound α is a linear or branched hydrocarbon group or a cyclic hydrocarbon group having 2 to 13 carbon atoms. Examples of the ligand L1 include the trimethylene ligand (ligand L1) described below. 10 ), butadienyl ligands, pentadienyl ligands, hexadienyl ligands, heptadienyl ligands, etc.

[0081] On the other hand, as the ligand X of the organic ruthenium compound α, any one of a carbonyl ligand (CO), an isonitrile ligand (L2), a pyridine ligand (L3), an amine ligand (L4), an imidazole ligand (L5), a pyridazine ligand (L6), a pyrimidine ligand (L7), and a pyrazine ligand (L8) can be used. The specific contents of the ligands L2 to L8 are as follows.

[0082] ·Isonitrile ligand (L2)

[0083] The isonitrile ligand (L2) is a ligand represented by the formula of the above chemical formula 6. The substituent R1 of the 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, and a linear or branched fluoroalkyl group having 1 to 8 carbon atoms. When the ligand X is an isonitrile ligand, the substituent R1 of the ligand L2 is preferably any one of the following groups: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, cyclohexyl, trifluoromethyl, or pentafluoroethyl.

[0084] Pyridine ligand (L3)

[0085] The pyridine ligand (L3) is a ligand represented by the formula of the above chemical formula 7. The substituents R2 to R6 of the ligand L3 are each any one of the following groups: 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, and a linear or branched nitro group having 1 to 5 carbon atoms. When the ligand X is a pyridine ligand, any of the following situations is preferred: R2 to R6 are all hydrogen; or R2, R4 and R6 are all methyl groups, and R3 and R5 are hydrogen; or R2, R3, R5 and R6 are all hydrogen, and R4 is any one of methyl, ethyl, isopropyl, tert-butyl, trifluoromethyl, methoxy, cyano and nitro.

[0086] Amine ligand (L4)

[0087] The amine ligand (L4) is a ligand represented by the formula of the above chemical formula 8. The substituents R7 to R9 of the ligand L4 are each a linear or branched alkyl group having 1 to 5 carbon atoms. When the ligand X is an amine ligand, any of the following situations is preferred: R7 to R9 are all methyl, ethyl, n-propyl, isopropyl, and n-butyl; or R7 and R8 are all methyl, ethyl, n-propyl, isopropyl, n-butyl, or tert-butyl, and R9 is hydrogen.

[0088] Imidazole ligand (L5)

[0089] The imidazole ligand (L5) is a ligand represented by the above Chemical Formula 9. The substituent R of the ligand L5 10is any one of the following groups: 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. 11 ~R 13 Each is any one of the following groups: 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, hydrogen or a linear or branched fluoroalkyl group having 1 to 5 carbon atoms. When the ligand X is an imidazole ligand, any of the following is preferred: R 10 ~R 13 All hydrogen; or R 10 is any one of methyl, ethyl, isopropyl, tert-butyl, and trifluoromethyl, R 11 ~R 13 is any one of hydrogen, methyl or ethyl; or R 10 is any one of methyl, ethyl, isopropyl, tert-butyl, and trifluoromethyl, R 11 ~R 13 Each of them is any of hydrogen, methyl or ethyl.

[0090] ·Pyridazine ligand (L6)

[0091] The pyridazine ligand (L6) is a ligand represented by the above Chemical Formula 10. The substituent R of the ligand L6 14 ~R 17 Each is any one of the following groups: 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, hydrogen or a linear or branched nitro group having 1 to 5 carbon atoms. When the ligand X is a pyridazine ligand, any of the following is preferred: R 14 ~R 17 All hydrogen; or R 14 is any one of methyl, ethyl, isopropyl, tert-butyl, trifluoromethyl, fluoro, methoxy, cyano, or nitro, R 15 ~R 17 is any one of hydrogen, methyl or ethyl; or R 15 is any one of methyl, ethyl, isopropyl or tert-butyl, R 14 , R 16 and R17 are any of hydrogen, methyl or ethyl; or R 15 and R 16 All are methyl, R 14 and R 17 All are hydrogen.

[0092] Pyrimidine ligand (L7)

[0093] The pyrimidine ligand (L7) is a ligand represented by the above Chemical Formula 11. The substituent R of the ligand L7 18 ~R 21 Each is any one of the following groups: 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, hydrogen or a linear or branched nitro group having 1 to 5 carbon atoms. When the ligand X is a pyrimidine ligand, any of the following is preferred: R 18 ~R 21 All hydrogen; or R 19 , R 20 and R 21 All are methyl, R 18 is hydrogen; or R 18 is any one of methyl, ethyl, isopropyl, tert-butyl, trifluoro, fluoro, methoxy, cyano, or nitro, R 19 ~R 21 is any one of hydrogen, methyl or ethyl; or R 20 is any one of methyl, ethyl, isopropyl, tert-butyl, trifluoro, fluoro, methoxy, cyano, or nitro, R 18 , R 19 and R 21 Each of them is any of hydrogen, methyl or ethyl.

[0094] ·Pyrazine ligand (L8)

[0095] The pyrazine ligand (L8) is a ligand represented by the above Chemical Formula 12. The substituent R of the ligand L8 22 ~R 25 Each is any one of the following groups: 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, hydrogen or a linear or branched nitro group having 1 to 5 carbon atoms. When the ligand X is a pyrazine ligand, any of the following is preferred: R22 ~R 25 All hydrogen; or R 22 is any one of methyl, ethyl, isopropyl, tert-butyl, trifluoromethyl, fluoro, methoxy, cyano, or nitro, R 23 ~R 25 is any one of hydrogen, methyl or ethyl; or R 23 is any one of methyl, ethyl, isopropyl, tert-butyl, trifluoromethyl, fluoro, methoxy, cyano, or nitro, R 22 , R 24 and R 25 Each of them is any of hydrogen, methyl or ethyl.

[0096] Regarding the combination of the above-mentioned ligand L1 and ligand X, as an example of an organic ruthenium compound α useful in the present invention, the following organic ruthenium compound can be listed, in which the ligand L1 is a trimethylenemethane ligand and the ligand X is a carbonyl ligand (i.e., coordinated with three carbonyl ligands).

[0097] [Chemical formula 16]

[0098] L 10 Ru(CO)2X

[0099] [Chemical formula 17]

[0100]

[0101] In the organoruthenium compound, the trimethylenemethane ligand L 10 The substituent R is any one of the following groups: 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. The substituent R is more preferably any one of the following groups: 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.

[0102] Specifically, the ligand L 10The substituent R is preferably hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl (2-methylpropyl: 2-methylpropyl), sec-butyl (1-methylpropyl: 1-methylpropyl), tert-butyl (1,1-dimethylethyl: 1,1-dimethylethyl), n-pentyl, isopentyl (3-methylbutyl: 3-methylbutyl), neopentyl (2,2-dimethylpropyl: 2,2-dimethylpropyl), sec-pentyl (1-methylbutyl: 1-methylbutyl), tert-pentyl (1,1-dimethylpropyl: 1,1-dimethylpropyl), n-hexyl, isohexyl (4-methylpentyl: 4-methylpentyl), neohexyl (2,2-dimethylbutyl: 2,2-dimethylbutyl), sec-hexyl (1-methylpentyl: 1-methylpentyl), tert-hexyl (1,1-dimethylpentyl: 1,1-dimethylpentyl), cyclohexyl, cyclohexylmethyl, phenyl. More preferred are ethyl, n-propyl, n-butyl, isobutyl (2-methylpropyl: 2-methylpropyl), n-pentyl, isopentyl (3-methylbutyl: 3-methylbutyl), and neopentyl (2,2-dimethylpropyl: 2,2-dimethylpropyl).

[0103] (2)Organoruthenium compounds β

[0104] The organic ruthenium compound β is an organic ruthenium represented by the above-mentioned chemical formula 13. The organic ruthenium compound is an organic ruthenium compound in which two β-diketonate ligands and two carbonyl ligands are coordinated to ruthenium.

[0105] Substituent R of β-diketone ligand 26 , R 27 is hydrogen or an alkyl group having 1 to 4 carbon atoms. 26 , R 27 They may be the same or different from each other, and are preferably asymmetric γ-diketones that are different from each other. 26 The number of carbon atoms and R 27 The total number of carbon atoms is set to 2-5.

[0106] (3)Organoruthenium compounds γ

[0107] The organic ruthenium compound γ is an organic ruthenium represented by the above chemical formula 14. The organic ruthenium compound is a binuclear organic ruthenium compound with two rutheniums after metal bonding as the central metal, and a ligand L9 and a carbonyl ligand as ligands for bridging coordination with ruthenium. Ligand L9 is a monoimine containing one nitrogen atom, and is any one of the two ligands (L9-1) or (L9-2) represented by the above chemical formula 16. It should be noted that "bridged coordination" refers to stereo coordination in the form of bridging of one ligand with two rutheniums. Specifically, by coordinating with each ruthenium at the two positions represented by * in the above ligands (L9-1, L9-2), bridged coordination (one ligand with two rutheniums) is performed.

[0108] Regarding the substituent R of ligand L9 28 ~R 35 , in L9-1, R 28 ~R 30 The total number of carbon atoms of each substituent is preferably 3 or more and 10 or less. 31 ~R 35 The total number of carbon atoms of each substituent is preferably 2 or more and 10 or less. 28 ~R 35 The substituents that can be used may be the same as or different from each other, and each is any one of a hydrogen atom and an alkyl group having 1 to 4 carbon atoms. 28 ~R 35 In the case of an alkyl group, it may be either a linear or branched chain. The alkyl group is preferably any one of a methyl group, an ethyl group, a propyl group, or a butyl group.

[0109] Substituent R of ligand L9-1 28 ~R 30 They may be the same or different from each other, and at least one of them is preferably any one of ethyl, propyl or butyl. R1 and R3 are also preferably branched alkyl groups. Specifically, as suitable substituents, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, or tert-butyl can be used, preferably ethyl, isopropyl, isobutyl, sec-butyl, or tert-butyl.

[0110] R 29 Preferably, it is a hydrogen atom or a methyl group, and particularly preferably a hydrogen atom. 29 When the ligand L9 is bridge-coordinated with ruthenium, it is located in a stereoscopic direction relative to the plane of metallic bonding with ruthenium. When the substituent has a low carbon number, a stable and easily vaporizable complex is easily obtained.

[0111] Substituent R as ligand L9-2 31 ~R 35 Suitable substituents, R 31Preferably, it is any one of ethyl, propyl or butyl. 31 A branched alkyl group is also preferred. Specifically, as a suitable substituent, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, or tert-butyl can be used, and ethyl, isopropyl, isobutyl, sec-butyl, or tert-butyl is preferred. 32 , R 33 , R 34 and R 35 They may be the same as or different from each other, and are each preferably a hydrogen atom or a methyl group, and particularly preferably a hydrogen atom.

[0112] The organic ruthenium compounds α, β, and γ as the precursors (1) to (3) described above can be directly heated to become a raw material gas, or a solution obtained by dissolving the organic ruthenium compounds in an appropriate solvent can be heated to become a raw material gas.

[0113] (I) First Film Forming Step

[0114] The first film forming step is a step of forming a ruthenium thin film or the like on a substrate using the above-mentioned organic ruthenium compounds α, β, and γ as precursors and a non-oxidizing gas as a reaction gas. This film forming step is a step in the initial stage of forming a base thin film such as a ruthenium thin film for manufacturing purposes while suppressing oxidation of the substrate.

[0115] The non-oxidizing gas used as the reaction gas in the first film forming step refers to a gas other than an oxidizing gas. Here, the oxidizing gas is a gas substance that is more likely to cause or support the combustion of other substances by supplying oxygen than air, and more specifically, a gas substance corresponding to type 1 in the GHS classification. In the present invention, preferred non-oxidizing gases include hydrogen, water vapor, ammonia, amine compounds, hydrazine derivatives, and the like.

[0116] It should be noted that the amine compound is a compound represented by "R-NH2", "RR'-NH", "RR'R"-N", and the substituents R, R', and R" in the formula are selected from the group consisting of the following groups: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl (2-methylpropyl: 2-methylpropyl), sec-butyl (1-methylpropyl: 1-methylpropyl), tert-butyl (1,1-dimethylethyl: 1,1-dimethylethyl), n-pentyl, isopentyl (3-methylbutyl: 3-methylbutyl), neopentyl (2,2-dimethylbutyl), ropyl: 2,2-dimethylpropyl), sec-pentyl (1-methylbutyl: 1-methylbutyl), tert-pentyl (1,1-dimethylpropyl: 1,1-dimethylpropyl), n-hexyl, isohexyl (4-methylpentyl: 4-methylpentyl), neohexyl (2,2-dimethylbutyl: 2,2-dimethylbutyl), sec-hexyl (1-methylpentyl: 1-methylpentyl), tert-hexyl (1,1-dimethylpentyl: 1,1-dimethylpentyl), cyclohexyl, cyclohexylmethyl, cyclohexylethyl, phenyl, benzyl. R, R', and R" may be the same or different. R, R', and R" are more preferably selected from the group consisting of the following groups: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl (2-methylpropyl: 2-methylpropyl), sec-butyl (1-methylpropyl: 1-methylpropyl), tert-butyl (1,1-dimethylethyl: 1,1-dimethylethyl), n-pentyl, isopentyl (3-methylbutyl: 3-methylbutyl), neopentyl (2,2-dimethylpropyl: 2,2-dimethylpropyl), sec-pentyl (1-methylbutyl: 1-methylbutyl), and tert-pentyl (1,1-dimethylpropyl: 1,1-dimethylpropyl).

[0117] In addition, the hydrazine derivative is a compound represented by "H2N-NRR'", wherein the substituents R and R' are selected from the group consisting of the following groups: hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl (2-methylpropyl: 2-methylpropyl), sec-butyl (1-methylpropyl: 1-methylpropyl), tert-butyl (1,1-dimethylethyl: 1,1-dimethylethyl), n-pentyl, isopentyl (3-methylbutyl: 3-methylbutyl), neopentyl (2,2-dimethylpropyl: 2,2-di ... R and R' may be the same or different. R and R' are more preferably selected from the group consisting of the following groups: hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl (2-methylpropyl: 2-methylpropyl), sec-butyl (1-methylpropyl: 1-methylpropyl), tert-butyl (1,1-dimethylethyl: 1,1-dimethylethyl), n-pentyl, isopentyl (3-methylbutyl: 3-methylbutyl), neopentyl (2,2-dimethylpropyl: 2,2-dimethylpropyl), sec-pentyl (1-methylbutyl: 1-methylbutyl), tert-pentyl (1,1-dimethylpropyl: 1,1-dimethylpropyl).

[0118] In addition, the film thickness of the ruthenium thin film, etc. formed in the first film forming step is preferably set to be greater than 2nm and less than 5nm. The ruthenium thin film, etc. formed using a non-oxidizing gas tends to contain impurities such as carbon. Therefore, when the film thickness at this stage is too thick, the resistivity of the film after the second film forming step sometimes becomes higher. In addition, when the ruthenium thin film, etc. in the first film forming step is too thin, the substrate may be oxidized in the subsequent second film forming step using an oxidizing gas.

[0119] The film forming conditions of the first film forming step are arbitrarily set according to the characteristics of the organic ruthenium compounds α, β, and γ as precursors. The vapor pressures of the organic ruthenium compounds α, β, and γ are all relatively high, and they can be easily vaporized to become raw material gas. The heating temperature for vaporizing the precursor to generate the raw material gas is preferably set to 0° C. or more and 80° C. or less.

[0120] In addition, the film forming temperature during film formation is preferably set to be above 150°C and below 400°C. When it is less than 150°C, the decomposition reaction of the organic ruthenium compound is difficult to proceed, and the film formation is slow. On the other hand, when the film forming temperature exceeds 400°C, there are problems such as difficulty in uniform film formation and possible damage to the substrate. The film forming temperature refers to the surface temperature of the substrate, which is usually adjusted by the heating temperature of the substrate.

[0121] It should be noted that, in the ALD method, as described above, a cycle consisting of an adsorption process / raw material gas purge process / reaction process / reaction gas purge process is repeated multiple times as a prerequisite. At this time, in the second and subsequent cycles, ruthenium and the like may sometimes be precipitated on the ruthenium film and the like of the previous cycle. In this case, a film will not be formed directly on the substrate in this cycle, but this cycle is of course also within the scope of the first film forming process. 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 forming process.

[0122] (II) Second film forming step

[0123] The second film forming step is a step of forming a film on the ruthenium thin film or the like formed in the first film forming step using an oxidizing gas as a reaction gas. This film forming step is basically different from the first film forming step only in the reaction gas. Therefore, the second film forming step can be performed in the same reactor after the first film forming step.

[0124] The significance of the oxidizing gas as the reaction gas in the second film forming step is as described above. As a suitable oxidizing gas in the present invention, any one of oxygen and ozone can be mentioned.

[0125] The film forming conditions of the second film forming process are also arbitrarily set according to the characteristics of the organic ruthenium compound as a precursor. In addition, the heating temperature for gasification of the precursor is preferably set to 0°C or more and 80°C or less, as in the first film forming process. Moreover, the film forming temperature during film formation can be set while considering that the reaction gas becomes an oxidizing gas, and can be set to the same range as the first film forming process. That is, the film forming temperature is preferably set to 150°C or more and 400°C or less.

[0126] The second film forming step is a step of forming a ruthenium thin film or the like having a target film thickness. Therefore, the film thickness of the ruthenium thin film or the like formed in this step is not limited.

[0127] After the first film forming step and the second film forming step described above, a ruthenium thin film or the like having a desired film thickness is formed. There is no restriction on the film thickness of the ruthenium thin film or the like formed by the method of the present invention. For example, in the formation of a thin ruthenium film of the order of 10 nm (less than 20 nm), compared with the film formation using an oxidizing gas to date, the resistivity of the film can be optimized while suppressing the oxidation of the substrate. When the substrate is oxidized by an oxidizing gas, the thinner the film thickness of the film, the greater the impact. According to the present invention, a thin film with lower resistance can be formed by suppressing the oxidation of the substrate. In addition, when the film thickness is increased, effective film formation can be performed compared to the film forming method using a non-oxidizing gas as a reaction gas to date. This is because, after the thin film serving as the basis is formed by the first film forming step, an oxidizing gas with excellent reactivity is used as a reaction gas.

[0128] B. Ruthenium thin film etc. involved in the present invention

[0129] The present invention also proposes a ruthenium thin film or a ruthenium compound thin film formed on a suitable substrate. The ruthenium thin film or the like involved in the present invention is oxygen-free on the substrate surface, and can suppress the resistance increase caused by substrate oxidation even in the case of a thin film thickness. That is, the present invention is a thin film composed of ruthenium or a ruthenium compound formed on a substrate, and the thin film does not contain oxygen at the interface with the substrate.

[0130] In addition, the ruthenium thin film etc. involved in the present invention also reduces the impurity content in the thin film. The above-mentioned organic ruthenium compound contains ligands with carbon as a constituent element, such as carbonyl ligands, which may be mixed into the thin film during film formation. The ruthenium thin film etc. involved in the present invention also suppresses the mixing of impurities and suppresses the increase in resistance caused by this. In the ruthenium thin film etc. involved in the present invention, the average carbon concentration near the outermost surface of the film is reduced. Regarding the suppression of impurities in the ruthenium thin film etc. involved in the present invention, if it is specifically described, the average carbon concentration in the range of 10nm to 25nm from the outermost surface of the film is reduced to less than 0.05 atomic%.

[0131] However, at the interface between the substrate and the film, a trace amount of carbon caused by film formation of a non-oxidizing gas is sometimes contained. Trace carbon is observed on the substrate surface (interface between the substrate and the film). Specifically, the average carbon concentration in the region from the substrate surface to 10 nm is 0.2 atomic % or more and 0.5 atomic % or less. The carbon concentration near the substrate surface is more preferably 0.2 atomic % or more and 0.5 atomic % or less in the region from the substrate surface to 5 nm.

[0132] However, since the carbon is contained in an extremely small amount near the extreme surface of the substrate, the influence on the resistance of the entire thin film is small.

[0133] In addition, as a structural feature of the ruthenium thin film etc. involved in the present invention, the surface roughness (surface roughness) is reduced. According to the inventors, in the film formation using non-oxidizing gas, the nucleation delay is short, and fine crystals tend to be formed to form a thin film with a smooth surface. In the present invention, by forming a smooth thin film in the initial stage and forming a film thereon using an oxidizing gas, the surface roughness is reduced compared to a thin film formed only by a non-oxidizing gas. As factors affecting the resistivity of the film, surface scattering, grain boundary scattering, surface roughness, etc. are interrelated. In the ruthenium thin film etc. involved in the present invention, it is particularly examined to achieve low resistance by improving the surface roughness. The reduction in the surface roughness of such a film is particularly helpful in reducing the resistance of a thin film with a small film thickness.

[0134] The thickness of the ruthenium thin film or the like according to the present invention is not limited. However, since the ruthenium thin film or the like according to the present invention suppresses oxidation of the substrate, it is particularly useful for thin films with a thickness of 20 nm or less that may be affected by substrate oxidation.

[0135] Effects of the Invention

[0136] As described above, the method for producing a ruthenium thin film or the like by chemical vapor deposition according to the present invention comprises a two-stage film forming process. The present invention utilizes the advantages of both non-oxidizing gas and oxidizing gas to efficiently form a low-resistance ruthenium thin film or the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0137] [ Figure 1 ] is a diagram illustrating a manufacturing process of a ruthenium thin film including a two-stage film forming process using the ALD method according to an embodiment of the present application.

[0138] [ Figure 2 ] is a FE-SEM photograph of the ruthenium thin films of Example 1 and Example 2 manufactured in the first embodiment.

[0139] [ Figure 3 ] is the GI-XRD diffraction pattern of the ruthenium thin films of Examples 1, 2 and Comparative Example 1 manufactured in the first embodiment.

[0140] [ Figure 4 ] is a diagram showing the results of composition analysis in the depth direction of the ruthenium thin films of Example 1 and Comparative Examples 1 and 2 manufactured in the first embodiment.

[0141] [ Figure 5 ] is a graph showing the resistivity of the ruthenium thin films of Examples 1, 2 and Comparative Examples 1, 2 manufactured in the first embodiment.

[0142] [ Figure 6 ] is a graph showing the film thickness and resistivity of the ruthenium thin films of Example 3 and Comparative Example 3 manufactured in the second embodiment. DETAILED DESCRIPTION

[0143] First Embodiment : The best embodiment of the present invention is described below. In this embodiment, the organic ruthenium compound used as a precursor is an organic ruthenium compound α, and the ligand L1 used is a trimethylene methane ligand (L 10 :R=hydrogen) and ligand X is carbonyl coordinated (η 4 -methylene-1,3-propanediyl)tricarbonylruthenium (chemical formula 4), hydrogen is used as a non-oxidizing reaction gas in the first film forming step, oxygen is used as an oxidizing gas reaction gas in the second film forming step, and a ruthenium thin film is formed by an ALD method. In addition, for comparison, a ruthenium thin film is formed in a single step of a conventional method using only oxygen or only hydrogen as a reaction gas.

[0144] As a precursor (η 4 -methylene-1,3-propanediyl)tricarbonylruthenium is synthesized as follows. 50.0g (97.5mmol) of tricarbonyl-dichlororuthenium dimer is suspended in 1700ml of tetrahydrofuran, and 300ml of 3-chloro-2-(chloromethyl)-1-propylene is added to 29.2g (231.6mmol) of tetrahydrofuran solution. 19.7g (800mmol) of magnesium turnings are slowly added, and then reacted at room temperature for 3 hours. 5mL of methanol is added to the reaction mixture for quenching, and the solvent is removed by distillation under reduced pressure. The obtained residue is extracted 3 times with 30mL of pentane, and the solvent is removed by distillation under reduced pressure. By sublimating and purifying the obtained oil, 16.3g (68.3mmol) of a colorless liquid as the target product (yield 35%) is obtained. The synthesis reaction of the organic ruthenium compound is as follows.

[0145] [Chemical formula 18]

[0146]

[0147] [Film formation of ruthenium thin film]

[0148] The process flow of the ruthenium thin film manufacturing process using the ALD method in this embodiment is as follows: Figure 1 As described above, the film forming process using the ALD method is composed of (i) an adsorption process of introducing a raw material gas to a substrate, (ii) a raw material gas purge process of exhausting the remaining raw material gas, (iii) a reaction process of introducing a reaction gas to form a thin film, and (iv) a reaction gas purge process of exhausting the remaining reaction gas. These steps are repeated as one cycle until the target film thickness is reached.

[0149] In this embodiment, a Si substrate (2 cm×2 cm) having a TiN film (thickness 20 nm) on its surface is used as a film-forming substrate to form a ruthenium thin film. The film forming conditions in the first and second film forming steps are as follows.

[0150] (I) First Film Forming Step

[0151] (i) Raw material gas introduction step

[0152] Raw material heating temperature: 10℃

[0153] Carrier gas: Nitrogen (50 sccm)

[0154] Import time: 5 seconds

[0155] (ii) Raw Gas Purge Step

[0156] Purge gas: Nitrogen (100 sccm)

[0157] Import time: 20 seconds

[0158] (iii) Reaction Gas Introduction Step

[0159] Reaction gas: Hydrogen (50 sccm)

[0160] Import time: 30 seconds

[0161] (iv) Reaction Gas Purge Step

[0162] Purge gas: Nitrogen (100 sccm)

[0163] Import time: 10 seconds

[0164] (II) Second film forming step

[0165] (i) Raw material gas introduction step

[0166] Raw material heating temperature: 10℃

[0167] Carrier gas: Nitrogen (50 sccm)

[0168] Import time: 10 seconds

[0169] (ii) Raw Gas Purge Step

[0170] Purge gas: Nitrogen (100 sccm)

[0171] Import time: 10 seconds

[0172] (iii) Reaction Gas Introduction Step

[0173] Reactive gas: oxygen (50 sccm)

[0174] Import time: 10 seconds

[0175] (iv) Reaction Gas Purge Step

[0176] Purge gas: Nitrogen (100 sccm)

[0177] Import time: 10 seconds

[0178] In this embodiment, the film thickness of the ruthenium thin film formed in the first film forming step (reaction gas: hydrogen) is set to 2 nm (Example 1) and 4 nm (Example 2). Then, in the second film forming step (reaction gas: oxygen), the ruthenium thin film is formed so that the final film thickness becomes 40 nm (Example 1: 38 nm film formation, Example 2: 36 nm film formation).

[0179] In addition, as a comparative example, a ruthenium thin film was formed by a single-stage ALD method using only oxygen (Comparative Example 1) or only hydrogen (Comparative Example 2) as a reaction gas. In these comparative examples, the number of cycles was controlled under the same conditions as in the first and second film forming steps described above, and a 40 nm thick ruthenium thin film was formed.

[0180] Figure 2 FE-SEM (field emission scanning electron microscope) cross-sectional photographs of the ruthenium thin films of Examples 1 and 2 of this embodiment are shown. Figure 3 The XRD diffraction patterns of GI-XRD (grazing incidence X-ray diffraction) of the ruthenium thin films of Examples 1, 2 and Comparative Example 1 are shown. Regarding the crystallinity of the ruthenium thin film, it can be considered that the ruthenium thin film formed in the two-stage film of this embodiment is the same as the conventional one-stage film. Based on the results of the GI-XRD, the crystal grain size of each ruthenium thin film was calculated, and the results were 29.3nm for Example 1, 28.5nm for Example 2, and 32.2nm for Comparative Example 1. It can be considered that the grain size of Examples 1 and 2 formed by hydrogen in the first film forming step is smaller than that of Comparative Example 1 formed by oxygen only. As described above, in the film forming using a non-oxidizing gas, fine grains can be formed quickly because the nucleation delay is short. It is believed that Examples 1 and 2 grow thin films on the fine ruthenium crystals formed in this way. Then, the surface roughness of Example 1 and Comparative Example 1 was observed by an atomic force microscope. As a result, it was confirmed that the surface roughness of Comparative Example 1 was 2.0 nm, whereas the surface roughness of Example 1 was reduced to 1.8 nm.

[0181] in addition, Figure 4The results of the composition analysis in the depth direction of SIMS (secondary ion mass spectrometry) performed on the ruthenium thin films of Example 1, Comparative Example 1, and Comparative Example 2 are shown. It was confirmed that the ruthenium thin film of Comparative Example 2, which was formed in one stage using only hydrogen, contained carbon (C) at the substrate interface and in the film. In the case of the ruthenium thin film of Comparative Example 2, which was formed in one stage using only oxygen, it was not confirmed that such a film contained carbon. Moreover, it was not confirmed that the film contained carbon in Example 1. In addition, by comparing Example 1 with Comparative Example 1, it can be confirmed that there is a slight presence of oxygen (O) at the interface with the substrate in Comparative Example 1. With reference to these, it can be said that according to the two-stage film formation using hydrogen and oxygen in Example 1, the mixing of oxygen at the substrate interface (substrate oxidation) and the mixing of carbon in the film can be suppressed, and a high-purity ruthenium thin film can be manufactured.

[0182] Next, the specific resistance of the ruthenium thin films of Examples 1 and 2 and Comparative Examples 1 and 2 was measured. The specific resistance was measured by a four-probe method. The results of the measurement are shown in FIG. Figure 5 As shown. Comparative Example 2 has the highest resistivity among these ruthenium thin films. As described above, it is believed that the ruthenium thin film formed using hydrogen as a non-oxidizing gas contains impurities such as carbon, thereby increasing the resistivity. As a result, it is believed that the resistivity of Comparative Example 1 is higher than that of the ruthenium thin film using oxygen in Comparative Example 1.

[0183] Compared with these comparative examples, the resistivity of the ruthenium thin film of Example 1 using a two-stage film forming process is lower than that of the ruthenium thin film of Comparative Example 1 using oxygen. It can be considered that by applying hydrogen in the first film forming process to suppress the oxidation of the substrate, and by applying oxygen in the second film forming process to rapidly perform the film forming reaction and release of impurities, the low resistance of the film can be achieved. In addition, with respect to Example 2, the resistivity is higher than that of Comparative Example 1, but the difference is very small and is at the same level. In Example 2, by applying a non-oxidizing gas in the first film forming process, the concern about damage caused by substrate oxidation can be almost completely eliminated. Considering this, it can be considered that Example 2 has obtained the same good results as Example 1. Regarding the evaluation of this Example 2, the film is obviously low in resistivity compared to the film of Comparative Example 2, so it is also a supportable evaluation.

[0184] Second Embodiment :In this embodiment, a two-stage film forming process is applied, and the change of the specific resistance when the film thickness of the ruthenium thin film is increased is studied. Under the same conditions as the first embodiment, a 2nm ruthenium thin film is formed in the first film forming process (reaction gas: hydrogen), and a ruthenium thin film is formed in the second film forming process (reaction gas: oxygen). At this time, the ruthenium thin film is formed in such a way that the final film thickness of the second film forming process is set to 5nm, 12nm, 18nm, and 23nm (Example 3). Then, the specific resistance of the ruthenium thin film of each film thickness is measured.

[0185] As a comparative example of Example 3, ruthenium thin films with thicknesses of 6 nm, 10 nm, 15 nm, and 20 nm were formed in a single-stage film-forming process in which the reaction gas was oxygen, and the resistivity was measured (Comparative Example 3).

[0186] The results of the measurement of the specific resistance of these ruthenium films are as follows Figure 6 As shown. Figure 6 It can be confirmed that the specific resistance of the ruthenium thin film (Example 3) using a two-stage film forming process is equal to or less than that of the ruthenium thin film (Comparative Example 3) using a one-stage film forming process in which the reaction gas is set to oxygen. In particular, in thin films with a small film thickness (less than 12nm), the specific resistance of the film formed by the two-stage film forming process is low. It is believed that this is due to the application of a non-oxidizing gas in the first film forming process to suppress the oxidation of the substrate and the effect of a small particle size and reduced surface roughness. It is believed that the low resistance of this extremely thin ruthenium film is useful in thin film electrodes of miniaturized semiconductor devices.

[0187] Industrial Applicability

[0188] As described above, the manufacturing method of the ruthenium thin film etc. using the two-stage film forming process according to the present invention can form the ruthenium thin film etc. with high quality and low specific resistance while suppressing the oxidation of the substrate. The present invention is suitable for use as a wiring / electrode material for semiconductor devices such as DRAM. In particular, it can also cope with the miniaturization of the wiring of ultra-miniaturized semiconductor devices.

Claims

1. A method for producing a ruthenium thin film or a ruthenium compound thin film, which is a method for producing a ruthenium thin film or a ruthenium compound thin film by a chemical vapor deposition method 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, characterized in that it comprises: A first film forming step, wherein a non-oxidizing gas is introduced as the reaction gas to form a ruthenium thin film or a ruthenium compound thin film on the surface of the substrate; as well as a second film forming step, wherein after the film is formed by the first film forming step, an oxidizing gas is introduced as the reaction gas to form a ruthenium thin film or a ruthenium compound thin film, As the organic ruthenium compound introduced in the first film forming step and the second film forming step, any one of the following organic ruthenium compounds α, β, and γ is used: (1) organic ruthenium compound α [Chemical formula 1] L1Ru(CO)2X In the formula, the ligand L1 is a linear or branched hydrocarbon group or a cyclic hydrocarbon group having 2 to 13 carbon atoms; in addition, the ligand X is a carbonyl ligand (CO) or any one of an isonitrile ligand (L2), a pyridine ligand (L3), an amine ligand (L4), an imidazole ligand (L5), a pyridazine ligand (L6), a pyrimidine ligand (L7), and a pyrazine ligand (L8) represented by the following chemical formulas 2 to 8, [Chemical formula 2] In the above formula, the substituent R1 of the isonitrile ligand L2 is any one of the following groups: hydrogen, a linear or branched alkyl group having 1 to 8 carbon atoms, or 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. [Chemical formula 3] In the above formula, the substituents R2 to R6 of the pyridine ligand L3 are each any one of the following groups: 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, and a linear or branched nitro group having 1 to 5 carbon atoms. [Chemical formula 4] In the above formula, the substituents R7 to R9 of the amine ligand L4 are each a linear or branched alkyl group having 1 to 5 carbon atoms. [Chemical formula 5] In the above formula, the substituent R of the imidazole ligand L5 is 10 is any one of the following groups: 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; the substituent R 11 ~R 13 Each is any one of the following groups: 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, and a linear or branched fluoroalkyl group having 1 to 5 carbon atoms. [Chemical formula 6] In the above formula, the substituent R of the pyridazine ligand L6 is 14 ~R 17 each is any one of the following groups: 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, hydrogen or a linear or branched nitro group having 1 to 5 carbon atoms, [Chemical formula 7] In the above formula, the substituent R of the pyrimidine ligand L7 is 18 ~R 21 each is any one of the following groups: 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, and a linear or branched nitro group having 1 to 5 carbon atoms, [Chemical formula 8] In the above formula, the substituent R of the pyrazine ligand L8 is 22 ~R 25 each is any one of the following groups: 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, and a linear or branched nitro group having 1 to 5 carbon atoms, (2)Organoruthenium compounds β [Chemical formula 9] In the formula, R 26 , R 27 may be the same as or different from each other, and each is any one of a hydrogen atom and an alkyl group having 1 to 4 carbon atoms, (3)Organoruthenium compounds γ [Chemical formula 10] In the formula, the ligand L9 is a ligand represented by any one of the following formulas (L9-1) or (L9-2), and is a ligand containing one nitrogen atom, [Chemical formula 11] Where * is the position of the atom that is bridged and coordinated with ruthenium; R 28 ~R 35 They may be the same as or different from each other, and are each any one of a hydrogen atom and an alkyl group having 1 to 4 carbon atoms.

2. The method for producing a ruthenium thin film or a ruthenium compound thin film according to claim 1, wherein: The organic ruthenium compound introduced in the first film forming step and the second film forming step is the following organic ruthenium compound: [Chemical formula 12] L 10 Ru(CO)2X In the formula, ligand L 10 It is represented by the following chemical formula 13, which is a trimethylene methane ligand. [Chemical formula 13] In the above formula, the trimethylene methane ligand L 10 The substituent R is any one of the following groups: hydrogen, a straight-chain or branched alkyl group having 1 to 8 carbon atoms, a cyclic alkyl group having 3 to 9 carbon atoms, a straight-chain or branched alkenyl group having 2 to 8 carbon atoms, a straight-chain or branched alkynyl group having 2 to 8 carbon atoms, a straight-chain or branched amino group having 2 to 8 carbon atoms, or an aryl group having 6 to 9 carbon atoms.

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

4. The 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 forming step is either oxygen or ozone.

5. The method for producing a ruthenium thin film or a ruthenium compound thin film according to claim 3, wherein: The oxidizing gas in the second film forming step is either oxygen or ozone.

6. The method for producing a ruthenium thin film or a ruthenium compound thin film according to claim 1 or claim 2, wherein: In the first film forming step, a ruthenium thin film or a ruthenium compound thin film is formed to have a film thickness in a range of 2 nm to 5 nm.

7. A thin film formed on a substrate and comprising ruthenium or a ruthenium compound, The thin film does not contain oxygen at the interface with the substrate.

Images