Method for producing copper-containing layer

Abstract

A method for producing a copper-containing layer, comprising: step 1 of reducing a surface of a substrate (excluding a substrate having a surface comprising of a silicic acid compound) with a reducing agent; and step 2 of forming a copper-containing layer on the surface that has been reduced in step 1 by a plasma atomic layer deposition method using a thin-film-forming raw material containing a copper compound.

Description

[Technical field]

[0001] The present invention relates to a method for producing a copper-containing layer having low electrical resistivity. [Background technology]

[0002] In semiconductors, by narrowing the width of the wiring in the metal wiring circuit and the spacing between the wiring, the number of elements per unit area increases, the distance between the elements decreases, and the driving voltage can be reduced. As a result, highly integrated semiconductors can achieve high-speed operation and low-power consumption operation. By using these semiconductors, electronic devices can be made smaller and lighter, with improved functionality and performance, lower power consumption, and lower prices. However, narrowing the width of the wiring increases the resistance per unit length and the current density, which increases the possibility of electromigration occurring and causing semiconductor failure. For this reason, the production of semiconductors using copper as a conductive material, which is less susceptible to electromigration, is increasing.

[0003] As a semiconductor using copper as a conductive material, for example, Patent Document 1 proposes forming a tantalum layer by physical vapor deposition (PVD) on a tantalum nitride layer formed by atomic layer deposition (ALD), and further forming copper on the tantalum layer by PVD. Non-Patent Document 1 shows that a copper metal film formed by plasma ALD using a copper complex on a substrate such as silica, titanium nitride, or tantalum has low electrical resistivity. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-502551 A [Non-patent literature]

[0005] [Non-Patent Document 1] "Trends in Copper Precursor Development for CVD and ALD Applications", ECS Journal of Solid State Science and Technology, 4(1), N3188-N3197, (2015) Summary of the Invention [Problem to be solved by the invention]

[0006] When a copper compound is used to form a copper thin film with a thickness of 20 nm or less by the ALD method on a metal substrate, the copper is likely to bond with the metal surface of the substrate, resulting in the generation of coarse copper particles, making the structure of the thin film uneven and increasing the electrical resistivity of the thin film. When a copper thin film is formed using a copper complex by the plasma ALD method, it is possible to produce a thin film with few impurities and a relatively low electrical resistivity. However, with the miniaturization of semiconductors, there has been a demand for further reducing the electrical resistivity of the copper-containing layer. [Means for solving the problem]

[0007] As a result of extensive investigations, the present inventors have found that a copper-containing layer produced through a specific process can solve the above problems, and have thus completed the present invention.

[0008] That is, the present invention provides a method for producing a copper-containing layer, characterized by comprising: step 1: reducing the surface of a substrate (excluding substrates whose surface is made of a silicate compound) using a reducing agent; and step 2: forming a copper-containing layer on the surface reduced in step 1 by plasma atomic layer deposition using a thin film forming raw material containing a copper compound.

[0009] In the method for producing a copper-containing layer of the present invention, the copper-containing layer preferably has a thickness of 20 nm or less.

[0010] In the method for producing a copper-containing layer of the present invention, the reducing agent is preferably at least one selected from the group consisting of hydrogen, ammonia, hydrazine, monosilane, disilane, diborane, trimethylaluminum, diethylzinc, and plasmas thereof.

[0011] In the method for producing a copper-containing layer of the present invention, the substrate is preferably a metal substrate or a substrate having a metal film formed on its surface.

[0012] In the method for producing a copper-containing layer of the present invention, the copper compound is preferably a copper compound represented by the following general formula (1).

[0013] [ka]

[0014] In the formula, R 1 , R 2 , R 5 and R 6 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a halogen atom; R 3 , R 4 , R 7 and R 8 each independently represents an alkyl group having 1 to 4 carbon atoms or a halogen atom.

[0015] In the production method of the present invention, step 1 is preferably carried out at a temperature in the range of 20°C to 400°C. Effect of the Invention

[0016] According to the invention, copper-containing layers having low electrical resistivity can be produced. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram showing an example of a plasma ALD apparatus used in the manufacturing method of the present invention. [Diagram 2] FIG. 1 is a schematic diagram showing another example of a plasma ALD apparatus used in the manufacturing method of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The method for producing a copper-containing layer of the present invention (hereinafter referred to as "the production method of the present invention") will be described. The manufacturing method of the present invention is characterized by having a step 1 of reducing a substrate using a reducing agent, and a step 2 of forming a copper-containing layer on the substrate using a plasma ALD method after the step 1, using a thin film forming raw material containing a copper compound. A known plasma ALD apparatus capable of performing plasma treatment on a reactive gas can be used for the manufacturing method of the present invention. Specific examples of plasma ALD apparatus include an apparatus as shown in FIG. 1, which can vaporize the thin film forming raw material in a raw material container by heating and / or reducing the pressure to form a vapor, and supply the vapor to a film formation chamber together with a carrier gas as necessary, and an apparatus as shown in FIG. 2, which can transport the thin film forming raw material in a liquid or solution state to a vaporization chamber, vaporize it in the vaporization chamber by heating and / or reducing the pressure to form a vapor, and supply the vapor to a film formation chamber. Note that the present invention is not limited to the single-wafer type apparatus equipped with a film formation chamber as shown in FIG. 1 and FIG. 2, but an apparatus capable of simultaneously processing multiple wafers using a batch furnace can also be used.

[0019] First, step 1 of the production method of the present invention will be described. In the manufacturing method of the present invention, step 1 is a process in which the substrate surface is reduced by applying heat to the substrate as necessary and bringing a reducing agent into contact with the substrate surface. Step 1 is preferably performed in a plasma ALD apparatus, and step 1 and step 2 are preferably performed consecutively in the plasma ALD apparatus.

[0020] The substrate used in the manufacturing method of the present invention may be any substrate other than a substrate having a surface made of a silicic acid compound, and may be, for example, a metal selected from the group consisting of aluminum, silver, gold, lead, vanadium, manganese, magnesium, iron, cobalt, nickel, copper, chromium, palladium, molybdenum, tungsten, platinum, titanium, zirconium and zinc, or an alloy such as brass, bronze, steel, stainless steel, aluminum alloy, magnesium alloy, titanium alloy, etc. Substrates having a surface made of a silicic acid compound are excluded because they do not provide the effect of the present invention, but substrates having a metal film formed on the surface of a silicic acid compound can be used in the manufacturing method of the present invention. Examples of methods for forming a metal film include a method in which a metal compound is used to form a metal film on the surface of a substrate by the AVD method or CVD method. Examples of metal compounds include "other precursors" described later.

[0021] The shape of the substrate may be a plate, a sphere, a fiber, a scale, etc. The surface of the substrate may be flat or may have a three-dimensional structure such as a trench structure.

[0022] (Substrate reduction treatment) In the manufacturing method of the present invention, in the step 1 of reducing the surface of the substrate, for example, when a metal substrate or a substrate having a metal film formed on its surface is used as the substrate, a reducing agent (gas) is brought into contact with the substrate surface to reduce the metal. Specifically, the substrate is placed in a deposition chamber of a plasma ALD device, and a reducing agent (gas) is introduced into the deposition chamber to reduce the substrate surface. At this time, the substrate may be heated, or the deposition chamber may be heated to apply heat. Step 1 is preferably performed at a temperature within the range of 20°C to 400°C. If the temperature is less than 20°C, no device capable of handling that temperature is available, while if the temperature exceeds 400°C, the substrate may not be able to withstand damage caused by heat.

[0023] Examples of the reducing agent include hydrogen, carbon monoxide, hydrogen sulfide, sulfur dioxide, ammonia, hydrazine, monosilane, disilane, diborane, trimethylaluminum (TMA), diethylzinc (ZnEt2), and the like, and plasma treatment of these agents can also be used. In the manufacturing method of the present invention, the reducing agent is preferably at least one selected from the group consisting of hydrogen, ammonia, hydrazine, monosilane, disilane, diborane, trimethylaluminum, diethylzinc, and plasmas thereof, and it is more preferable to use hydrogen plasma from the viewpoints of less damage to the substrate and less film contamination, and lowering the film formation temperature. The reducing agent can be introduced into the film formation chamber, for example, by reducing the pressure inside the film formation chamber.

[0024] As a method for performing plasma treatment on a reducing agent, for example, a method of irradiating a reducing agent with plasma emitted from a coil electrode can be mentioned. The plasma includes capacitively coupled plasma generated from an electrostatic field due to a high frequency voltage applied to a coil electrode, and inductively coupled plasma generated by an induced electric field generated by a high frequency current flowing through a coil electrode. These plasmas can be generated at a distance from the substrate, and damage to the substrate caused by the plasma can be suppressed.

[0025] When the reducing agent is irradiated with plasma, the plasma excitation frequency is preferably 13.56 MHz, and the plasma output is preferably 1 W to 600 W, and more preferably 20 W to 200 W. With an output of less than 20 W, the effect of the present invention may not be obtained, while an output of more than 200 W may cause significant damage to the substrate.

[0026] (Exhaust stroke) After the reduction treatment of the substrate, it is preferable to exhaust the reducing agent (gas) from the film formation chamber. At this time, it is ideal that the reducing agent (gas) is completely exhausted from the film formation chamber, but it is not necessarily required to exhaust it completely. Examples of the exhaust method include a method of purging the film formation chamber with an inert gas such as helium, nitrogen, or argon, a method of exhausting by reducing the pressure inside the film formation chamber, and a combination of these methods. When reducing the pressure, the degree of reduction is preferably in the range of 0.01 Pa to 300 Pa, and more preferably in the range of 0.01 Pa to 100 Pa.

[0027] Next, step 2 of the production method of the present invention will be described. Step 2 is a process in which a copper-containing layer is formed on the surface reduced in step 1 by a plasma ALD method using a thin film forming raw material containing a copper compound. Specifically, step 2 includes a step of introducing the vapor obtained by vaporizing the thin film forming raw material containing a copper compound and the vapor of other precursors used as necessary (hereinafter referred to as "raw material gas") into a film forming chamber (raw material gas introduction step), a step of depositing the copper compound in the raw material gas on the surface of the substrate to form a precursor layer (precursor layer formation step), a step of exhausting the unreacted raw material gas (exhaust step), and a step of introducing plasma of a reactive gas into the film forming chamber and reacting the precursor layer with the plasma of the reactive gas to form a copper-containing layer on the surface of the substrate (copper-containing layer formation step). Each of these steps will be described in detail below.

[0028] (Raw material gas introduction process) The step of vaporizing the thin film forming raw material into vapor (raw material gas) may be carried out in a raw material container, or may be carried out in a vaporization chamber by introducing the thin film forming raw material into the vaporization chamber.

[0029] Specific examples of the transport and supply method for introducing the raw material gas into the film formation chamber in the raw material gas introduction process include a gas transport method in which the raw material gas obtained by vaporizing the thin film raw material by heating and / or reducing the pressure in a storage container (hereinafter referred to as the "raw material container") as shown in Figure 1 is introduced into the film formation chamber (hereinafter referred to as the "deposition reaction section") in which a substrate is placed, together with a carrier gas such as argon, nitrogen, helium, etc. as necessary, as shown in Figure 1; and a liquid transport method in which the thin film raw material is transported in a liquid or solution state to a vaporization chamber, and vaporized by heating and / or reducing the pressure in the vaporization chamber, and the raw material gas obtained is introduced into the deposition reaction section as shown in Figure 2. In the case of the gas transport method, the copper compound itself can be used as the thin film forming raw material. In the case of the liquid transport method, the copper compound itself or a solution of the copper compound dissolved in an organic solvent can be used as the thin film forming raw material. The thin film forming raw material may further contain a nucleophilic reagent, etc.

[0030] The method of introducing the source gas into the deposition reaction section includes a single source method and a cocktail source method, and either method may be used. In either method, the thin film forming source material is preferably vaporized at 20° C. to 200° C. In addition, when the thin film forming source material is vaporized into vapor in the source container or vaporization chamber, the pressure in the source container and the vaporization chamber are preferably within the range of 1 Pa to 10,000 Pa.

[0031] The copper compound contained in the thin film forming raw material may be capable of forming a thin copper film, and the structure of the copper compound is not particularly limited. However, if the molecular weight of the copper compound exceeds 1,000, the melting point becomes too high, and it may be difficult to use the copper compound as a thin film forming raw material. The molecular weight of the copper compound is preferably less than 800, more preferably 200 to 600. In addition, in order to ensure transportability in the piping of the device for producing a thin film using the thin film forming raw material, the melting point of the copper compound is preferably 50°C or less, and more preferably it is liquid at room temperature.

[0032] Specific examples of copper compounds that can be used in the production method of the present invention include the following compounds 1 to 32, but the present invention is not limited to these compounds. In the following compounds, "Me" represents a "methyl group", "Et" represents an "ethyl group", "iPr" represents an "isopropyl group", "nPr" represents an "n-propyl group", "tBu" represents a "tert-butyl group", "sBu" represents a "sec-butyl group", "nBu" represents an "n-butyl group", and "SiMe3" represents a "trimethylsilyl group".

[0033] [ka]

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[0039] [ka]

[0040] [ka]

[0041] In particular, copper compounds represented by the following general formula (1) exhibit high vapor pressure and excellent thermal stability, and therefore can be preferably used in the production method of the present invention.

[0042] [ka]

[0043] (In formula (1), R 1 , R 2 , R 5 and R 6 each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a halogen atom; R 3 , R 4 , R 7 and R 8 each independently represents an alkyl group having 1 to 4 carbon atoms or a halogen atom.

[0044] R in the above general formula (1) 1 ~R 8 The alkyl group having 1 to 4 carbon atoms represented by the formula (1) may be linear or branched. Specific examples of the alkyl group having 1 to 4 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a n-butyl group, a sec-butyl group, a tert-butyl group, and an isobutyl group. An alkyl group having more than 4 carbon atoms may have a high melting point and may not be usable as a raw material for forming a thin film. The number of carbon atoms in the alkyl group is preferably 1 to 3. Among the copper compounds represented by the formula (1) above, R 1 and R 5 is a methyl group and R 2 and R 6 is a hydrogen atom, and R 1 and R 5 is a methyl group, and R 2 and R 6 is a hydrogen atom and R 3 , R 4 , R 7 and R 8However, copper compounds having a methyl group, an ethyl group, and an isopropyl group are more preferred.

[0045] In the above general formula (1), R 1 ~R 8 Examples of the halogen atom represented by the formula (I) include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc., and a chlorine atom is preferred.

[0046] Specific examples of the copper compound represented by the above general formula (1) include the above compounds 5 to 16, but the production method of the present invention is not limited to these copper compounds.

[0047] The method for producing the copper compound is not particularly limited, and the copper compound can be produced by applying a known reaction. For example, the copper compound can be obtained by the production method described in JP 2015-218117 A.

[0048] The thin film forming raw material may contain a copper compound and may be used as a precursor of a thin film, and the composition of the raw material varies depending on the type of the target thin film. For example, when producing a thin film containing only copper as a metal, the thin film forming raw material does not contain metal compounds and metalloid compounds other than copper. On the other hand, when producing a thin film containing copper and metals and / or metalloids other than copper, the thin film forming raw material may contain, in addition to the copper compound, a compound containing the desired metal and / or a compound containing a metalloid (hereinafter referred to as "other precursors").

[0049] In a multi-component ALD method using a plurality of precursors, other precursors that can be used together with the copper compound are not particularly limited, and any well-known precursors that are used as thin film forming materials for the ALD method can be used.

[0050] Examples of the other precursor include compounds comprising a metal and one or more compounds selected from the group consisting of compounds used as organic ligands, such as alcohol compounds, glycol compounds, β-diketone compounds, cyclopentadiene compounds, and organic amine compounds. Examples of the metal species of the precursor include lithium, sodium, potassium, magnesium, calcium, strontium, barium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, tungsten, manganese, iron, osmium, ruthenium, cobalt, rhodium, iridium, nickel, palladium, platinum, silver, gold, zinc, aluminum, gallium, indium, germanium, tin, lead, antimony, bismuth, radium, scandium, ruthenium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

[0051] Examples of the alcohol compounds that can be used as organic ligands for the other precursors include alkyl alcohols such as methanol, ethanol, propanol, isopropyl alcohol, butanol, sec-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, pentyl alcohol, isopentyl alcohol, and tert-pentyl alcohol; 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-(2-methoxyethoxy)ethanol, 2-methoxy-1-methylethanol, 2-methoxy-1,1-dimethylethanol, 2-ethoxy-1,1-dimethylethanol, and 2-isopropoxy-1,1-dimethylethanol. ether alcohols such as 2-butoxy-1,1-dimethylethanol, 2-(2-methoxyethoxy)-1,1-dimethylethanol, 2-propoxy-1,1-diethylethanol, 2-sec-butoxy-1,1-diethylethanol, and 3-methoxy-1,1-dimethylpropanol; and dialkylamino alcohols such as dimethylaminoethanol, ethylmethylaminoethanol, diethylaminoethanol, dimethylamino-2-pentanol, ethylmethylamino-2-pentanol, dimethylamino-2-methyl-2-pentanol, ethylmethylamino-2-methyl-2-pentanol, and diethylamino-2-methyl-2-pentanol.

[0052] Examples of glycol compounds used as organic ligands for the other precursors include 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 2,4-hexanediol, 2,2-dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 1,3-butanediol, 2,4-butanediol, 2,2-diethyl-1,3-butanediol, 2-ethyl-2-butyl-1,3-propanediol, 2,4-pentanediol, 2-methyl-1,3-propanediol, 2-methyl-2,4-pentanediol, 2,4-hexanediol, and 2,4-dimethyl-2,4-pentanediol.

[0053] Examples of the β-diketone compound used as the organic ligand of the other precursors include acetylacetone, hexane-2,4-dione, 5-methylhexane-2,4-dione, heptane-2,4-dione, 2-methylheptane-3,5-dione, 5-methylheptane-2,4-dione, 6-methylheptane-2,4-dione, 2,2-dimethylheptane-3,5-dione, 2,6-dimethylheptane-3,5-dione, 2,2,6-trimethylheptane-3,5-dione, 2,2,6,6-tetramethylheptane-3,5-dione, octane-2,4-dione, 2,2,6-trimethyloctane-3,5-dione, 2,6-dimethyloctane-3,5-dione, 2,9-dimethylnonane-4,6-dione, 2-methyl- Examples of the alkyl-substituted β-diketones include 6-ethyldecane-3,5-dione and 2,2-dimethyl-6-ethyldecane-3,5-dione; fluorine-substituted alkyl β-diketones include 1,1,1-trifluoropentane-2,4-dione, 1,1,1-trifluoro-5,5-dimethylhexane-2,4-dione, 1,1,1,5,5,5-hexafluoropentane-2,4-dione and 1,3-diperfluorohexylpropane-1,3-dione; and ether-substituted β-diketones include 1,1,5,5-tetramethyl-1-methoxyhexane-2,4-dione, 2,2,6,6-tetramethyl-1-methoxyheptane-3,5-dione and 2,2,6,6-tetramethyl-1-(2-methoxyethoxy)heptane-3,5-dione.

[0054] Examples of the cyclopentadiene compound used as the organic ligand of the other precursors include cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, propylcyclopentadiene, isopropylcyclopentadiene, butylcyclopentadiene, sec-butylcyclopentadiene, isobutylcyclopentadiene, tert-butylcyclopentadiene, dimethylcyclopentadiene, and tetramethylcyclopentadiene.

[0055] Examples of the organic amine compound used as the organic ligand include methylamine, ethylamine, propylamine, isopropylamine, butylamine, sec-butylamine, tert-butylamine, isobutylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, ethylmethylamine, propylmethylamine, and isopropylmethylamine.

[0056] The above other precursors are known in the art, and their manufacturing methods are also known. For example, when an alcohol compound is used as an organic ligand, the precursor can be manufactured by reacting the inorganic salt of the metal or its hydrate described above with an alkali metal alkoxide of the alcohol compound. Here, examples of the inorganic salt of the metal or its hydrate include metal halides and nitrates, and examples of the alkali metal alkoxide include sodium alkoxide, lithium alkoxide, potassium alkoxide, and the like.

[0057] In the multi-component ALD method as described above, there are a method in which each component of the thin film forming material is vaporized and supplied independently (hereinafter referred to as the "single source method"), and a method in which a mixed material in which multi-component materials are mixed in advance with a desired composition is vaporized and supplied (hereinafter referred to as the "cocktail source method").

[0058] In the case of the single source method, the other precursor is preferably a compound whose thermal and / or oxidative decomposition behavior is similar to that of the copper compound, whereas in the case of the cocktail source method, the other precursor is preferably a compound whose thermal and / or oxidative decomposition behavior is similar to that of the copper compound and which does not undergo deterioration due to chemical reactions or the like when mixed.

[0059] In the case of a cocktail source method in a multi-component ALD method, a mixture of a copper compound and other precursors or a mixed solution in which the mixture is dissolved in an organic solvent can be used as a thin film forming material.

[0060] The organic solvent is not particularly limited, and any well-known organic solvent can be used. Examples of the organic solvent include acetates such as ethyl acetate, butyl acetate, and methoxyethyl acetate; ethers such as tetrahydrofuran, tetrahydropyran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, dibutyl ether, and dioxane; ketones such as methyl butyl ketone, methyl isobutyl ketone, ethyl butyl ketone, dipropyl ketone, diisobutyl ketone, methyl pentyl ketone, cyclohexanone, and methylcyclohexanone; hydrocarbons such as hexane, cyclohexane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, heptane, octane, toluene, and xylene; hydrocarbons having a cyano group such as 1-cyanopropane, 1-cyanonobutane, 1-cyanohexane, cyanocyclohexane, cyanobenzene, 1,3-dicyanopropane, 1,4-dicyanobutane, 1,6-dicyanohexane, 1,4-dicyanocyclohexane, and 1,4-dicyanobenzene; pyridine, lutidine, and the like. These organic solvents may be used alone or in combination of two or more depending on the solubility of the solute, the relationship between the use temperature and the boiling point, the flash point, and the like.

[0061] When the thin film forming raw material used in the manufacturing method of the present invention is the above-mentioned mixed solution, it is preferable to prepare the thin film forming raw material so that the total amount of precursors is 0.01 mol / L to 2.0 mol / L, and more preferably 0.05 mol / L to 1.0 mol / L.

[0062] The total amount of precursors refers to the amount of copper compounds when the thin film forming raw material does not contain metal compounds or semi-metal compounds other than copper compounds, and refers to the total amount of copper compounds and other precursors when the thin film forming raw material contains other precursors.

[0063] The thin film forming raw material used in the manufacturing method of the present invention may contain a nucleophilic reagent, if necessary, to improve the stability of the copper compound and other precursors. Examples of the nucleophilic reagent include ethylene glycol ethers such as glyme, diglyme, triglyme, and tetraglyme, crown ethers such as 18-crown-6, dicyclohexyl-18-crown-6, 24-crown-8, dicyclohexyl-24-crown-8, and dibenzo-24-crown-8, ethylenediamine, N,N'-tetramethylethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, 1,1,4,7,7-pentamethyldiethylenetriamine, 1,1,4,7,10,10-hexamethyltriethylenetetramine, Examples of the nucleophilic reagent include polyamines such as triethoxytriethyleneamine, cyclic polyamines such as cyclam and cyclen, heterocyclic compounds such as pyridine, pyrrolidine, piperidine, morpholine, N-methylpyrrolidine, N-methylpiperidine, N-methylmorpholine, tetrahydrofuran, tetrahydropyran, 1,4-dioxane, oxazole, thiazole, and oxathiolane, β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, and 2-methoxyethyl acetoacetate, and β-diketones such as acetylacetone, 2,4-hexanedione, 2,4-heptanedione, 3,5-heptanedione, and dipivaloylmethane. The amount of the nucleophilic reagent is preferably in the range of 0.1 mol to 10 mol relative to 1 mol of the total amount of the precursor, and more preferably in the range of 1 mol to 4 mol.

[0064] In the manufacturing method of the present invention, it is desirable that the thin film forming raw material contains as little impurity metal elements, impurity halogens such as impurity chlorine, and impurity organic components as possible other than the components that constitute the thin film. The impurity metal elements are preferably 100 ppb or less per element, more preferably 10 ppb or less, and the total amount is preferably 1 ppm or less, more preferably 100 ppb or less. In particular, when used as a gate insulating film, gate film, or barrier layer of an LSI, it is necessary to reduce the content of alkali metal elements and alkaline earth metal elements that affect the electrical properties of the resulting thin film. The impurity halogens are preferably 100 ppm or less, more preferably 10 ppm or less, and even more preferably 1 ppm or less. The impurity organic components are preferably 500 ppm or less in total, more preferably 50 ppm or less, and even more preferably 10 ppm or less. In addition, moisture is a cause of particle generation in the thin film forming raw material and during thin film formation, so it is better to remove as much moisture as possible from the precursor, organic solvent, and nucleophilic reagent before use in order to reduce the moisture content of each. The moisture content of each of the precursor, the organic solvent and the nucleophilic reagent is preferably 10 ppm or less, more preferably 1 ppm or less.

[0065] In the manufacturing method of the present invention, it is preferable that the thin film forming raw material contains as few particles as possible in order to reduce or prevent particle contamination of the thin film to be formed. Specifically, in particle measurement in the liquid phase using a light scattering type liquid-borne particle detector, it is preferable that the number of particles larger than 0.3 μm is 100 or less per 1 ml of liquid phase, and it is more preferable that the number of particles larger than 0.2 μm is 100 or less per 1 ml of liquid phase.

[0066] (Precursor layer forming process) In the precursor layer forming step, a raw material gas is introduced into a substrate placed in a deposition reaction section, and a copper compound in the raw material gas is deposited on the surface of the substrate to form a precursor layer on the substrate. At this time, the substrate may be heated, or the deposition reaction section may be heated to apply heat. The conditions for forming the precursor layer are not particularly limited, and for example, the reaction temperature (substrate temperature), reaction pressure, deposition rate, etc. can be appropriately determined according to the type of thin film forming raw material. The reaction temperature is preferably 20°C or higher, which is a temperature at which the thin film forming raw material reacts sufficiently, more preferably 20°C to 400°C, and is used within the ALD window that matches the plasma of the reactive gas. The film thickness is controlled by the number of cycles so as to obtain a desired film thickness. The reaction pressure is preferably 1 Pa to 10,000 Pa, more preferably 10 Pa to 1,000 Pa.

[0067] When the thin film forming material contains precursors other than the copper compound, the precursors are also deposited on the surface of the substrate together with the copper compound.

[0068] (Exhaust process) After the precursor layer forming step, the source gas that has not been deposited on the surface of the substrate is exhausted from the deposition reaction section. Ideally, the source gas is completely exhausted from the deposition reaction section, but it is not necessarily required to completely exhaust it. Examples of the exhaust method include a method of purging the inside of the deposition reaction section with an inert gas such as helium, nitrogen, or argon, a method of exhausting by reducing the pressure inside the deposition reaction section, and a combination of these methods. When reducing the pressure, the degree of reduction in pressure is preferably in the range of 0.01 Pa to 300 Pa, and more preferably in the range of 0.01 Pa to 100 Pa.

[0069] (Copper-containing layer formation process) After the exhaust step, the plasma of the reactive gas is introduced into the deposition reaction section, and the plasma of the reactive gas is reacted with the precursor layer, i.e., the copper compound deposited on the surface of the substrate, by the action of the plasma of the reactive gas or the action of the plasma of the reactive gas and the action of heat, to form a copper-containing layer. The reactive gas may be plasma-treated in advance before being introduced into the deposition reaction section, or the reactive gas may be plasma-treated in the deposition reaction section. The plasma of the reactive gas can be generated by irradiating the reactive gas with plasma. The conditions of the plasma treatment may be the same as those of the plasma treatment performed on the reducing agent in step 1.

[0070] The reactive gas may be any gas that reacts with the precursor layer after plasma treatment, and examples of such gases include oxidizing gases such as hydrogen, oxygen, ozone, nitrogen dioxide, nitric oxide, water vapor, hydrogen peroxide, formic acid, acetic acid, and acetic anhydride, reducing gases such as hydrogen, organic amine compounds such as monoalkylamines, dialkylamines, trialkylamines, and alkylenediamines, and nitriding gases such as hydrazine and ammonia. The reactive gas may be used alone or in combination of two or more kinds. In the manufacturing method of the present invention, it is preferable to use hydrogen plasma as the reactive gas plasma, since the effect of the present invention is remarkable.

[0071] When the reaction between the precursor layer and the plasma of the reactive gas is performed using heat, the temperature is preferably in the range of room temperature to 400° C., more preferably in the range of 20° C. to 400° C. When the reaction between the precursor layer and the plasma of the reactive gas is performed at a low temperature, carbon impurities can be prevented from remaining in the resulting copper-containing layer, so the temperature is preferably in the range of 20° C. to 200° C., more preferably in the range of 20° C. to 150° C. The pressure in the deposition reaction zone when performing step 2 is preferably 1 Pa to 10,000 Pa, more preferably 10 Pa to 2,000 Pa.

[0072] (Exhaust stroke) After the copper-containing layer forming step, if necessary, the plasma of the unreacted reactive gas and the by-product gas are exhausted from the deposition reaction section. At this time, it is ideal that the reactive gas and the by-product gas are completely exhausted from the deposition reaction section, but it is not necessary to completely exhaust them. The exhaust method and the degree of pressure reduction when reducing the pressure are the same as those in the exhaust process after the precursor layer forming step described above.

[0073] In step 2 of the manufacturing method of the present invention, deposition through a series of operations consisting of a "raw material gas introduction step," a "precursor layer formation step," an "exhaust step," a "copper-containing layer formation step," and an "exhaust step" is considered as one cycle, and this cycle is repeated multiple times until a thin film with a required thickness is obtained, whereby a copper-containing layer with a desired thickness can be manufactured.

[0074] The deposition rate of the copper-containing layer can be controlled by the supply conditions of the thin film-forming raw material (vaporization temperature, vaporization pressure), the reaction temperature and reaction pressure of the thin film-forming raw material and the plasma of the reaction gas. If the deposition rate is high, the properties of the obtained copper-containing layer may deteriorate, and if it is low, problems may occur in productivity, so that the deposition rate is preferably 0.01 nm / min to 100 nm / min, and more preferably 0.05 nm / min to 50 nm / min.

[0075] After the copper-containing layer is formed, an annealing treatment may be performed in an inert atmosphere, an oxidizing atmosphere, or a reducing atmosphere in order to obtain better electrical properties, and a reflow process may be performed if step filling is required. The temperature in this case is preferably 200° C. to 1,000° C., more preferably 250° C. to 500° C.

[0076] The thickness of the copper-containing layer obtained by the manufacturing method of the present invention is preferably 20 nm or less, and more preferably 10 nm or less because the effect of the present invention is more pronounced. Also, the copper-containing layer obtained by the manufacturing method of the present invention preferably has a thickness of at least 1 nm.

[0077] The present invention provides a copper-containing thin film having a low electrical resistivity, and such a thin film can be used to coat metal, oxide ceramics, nitride ceramics, and glass substrates by appropriately selecting other precursors, reactive gases, and manufacturing conditions. The thin film manufactured by the manufacturing method of the present invention has excellent electrical properties and is therefore suitable for manufacturing electrode materials for memory elements such as DRAM elements, resistive films, diamagnetic films used in the recording layers of hard disks, and catalyst materials for solid polymer fuel cells. EXAMPLES

[0078] The present invention will be described in more detail below using examples, etc. However, the present invention is not limited to the following examples, etc.

[0079] (1) Copper compounds The following copper compounds were used as precursors for evaluation.

[0080] [ka]

[0081] (2) Circuit Board The following substrates A to C were used in the manufacturing method of the present invention and evaluated. Substrate A: A ruthenium metal film (thickness 20 nm) formed on a silica substrate using the PVD method. Substrate B: A cobalt metal film (thickness 15 nm) formed on substrate A using the PVD method. Substrate C: Silica substrate

[0082] The copper-containing layer obtained by the manufacturing method of the present invention was evaluated by the following methods.

[0083] [1] Root Mean Square (RMS) The RMS (nm) of the cross section of the copper-containing layer in the thickness direction was measured using FE-SEM. RMS is an index that indicates the uniformity of the thickness of the copper-containing layer, and it can be said that the smaller the RMS, the more uniform the thickness of the copper-containing layer. RMS is the square root of the average of the squares of the deviations from the average line to the measurement curve, and is expressed by the following formula (2).

[0084]

number

[0085] In formula (2), L is the reference length, and Z is the height from the average line to the measurement curve.

[0086] [2] Electrical resistivity The electrical resistivity (μΩcm) of the copper-containing layer was measured using a four-terminal method.

[0087] [3] Thickness The thickness (nm) of the copper-containing layer was measured by X-ray reflectivity method.

[0088] (Examples 1 to 8, Comparative Examples 1 to 5) First, in step 1, the substrate surface was heated to a temperature shown in Table 1, and then hydrogen plasma obtained by performing a plasma treatment on hydrogen gas under conditions of RF output: 100 W and irradiation time: 20 seconds was brought into contact with the substrate for 20 seconds to reduce the substrate surface. The substrate was selected from substrates A to C and used. Next, in step 2, a copper-containing layer was formed on the substrate surface by plasma ALD under conditions 1 or 2 shown in Table 2. The evaluation results of the obtained copper-containing layer are shown in Table 1. In Comparative Example 5, a copper-containing layer was formed in the same manner as in Example 1, except that step 1 was not performed on the substrate.

[0089] [Table 1]

[0090] [Table 2]

[0091] From the results of Comparative Examples 1 to 4, when a substrate (Substrate C) having a surface made of a silicate compound was used, a copper-containing layer of uniform thickness could not be formed. Moreover, from the results of Example 2 and Comparative Example 5, it was confirmed that when a copper-containing layer was formed by the plasma ALD method after reducing the substrate surface with hydrogen plasma, the RMS and electrical resistivity of the copper-containing layer were lower than when a copper-containing layer was formed by the plasma ALD method without reducing the substrate surface.

[0092] As described above, according to the manufacturing method of the present invention, a copper-containing layer having a uniform thickness and low electrical resistivity can be formed.

Claims

[Claim 1] Step 1: reducing the surface of the substrate using a reducing agent; Step 2: forming a copper-containing layer on the surface reduced in step 1 by plasma atomic layer deposition using a thin film forming material containing a copper compound represented by the following structural formula: having 【Chemistry 1】 the reducing agent is at least one selected from the group consisting of hydrogen, ammonia, hydrazine, monosilane, disilane, diborane, trimethylaluminum, diethylzinc, and plasmas thereof; The substrate is a metal substrate or a substrate having a metal film formed on its surface, The thickness of the copper-containing layer is 20 nm or less; The step 1 is carried out at a temperature in the range of 20°C to 400°C, The method for producing a copper-containing layer, wherein in the step 2, the temperature of the substrate is set to 20° C. to 40° C.

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