Etching method

Abstract

Provided is an etching method for a carbon film, said etching method comprising: (1) providing, inside a chamber, a substrate having a carbon film; and (2) etching the carbon film under plasma conditions using an etching gas that contains oxygen and a reaction accelerator, wherein, in the etching gas, the oxygen has the highest partial pressure, and the reaction accelerator includes an N atom.

Description

Etching method

[0001] This disclosure relates to an etching method.

[0002] A known method for etching carbon films is plasma etching using oxygen gas (Japanese Patent Publication No. 2007-180358 (Patent Document 1)).

[0003] Japanese Patent Publication No. 2007-180358

[0004] This disclosure aims to provide a method for more efficiently etching carbon films.

[0005] This disclosure includes the following embodiments: [Clause 1] An etching method for a carbon film, comprising: (1) providing a substrate having a carbon film in a chamber; and (2) etching the carbon film under plasma conditions using an etching gas containing a reaction accelerator, wherein the reaction accelerator contains N atoms. [Clause 2] The etching method according to Claim 1, wherein the etching gas further contains oxygen, and the partial pressure of oxygen is the highest in the etching gas. [Clause 3] The etching method according to Claim 1 or 2, wherein the reaction accelerator is a compound containing 5% or more N atoms relative to the total number of atoms. [Clause 4] The etching method according to any one of Claims 1 to 3, wherein the reaction accelerator is a compound containing 33% or more N atoms relative to the total number of atoms. [Clause 5] The reaction accelerator is -NR １ ２ (In the formula, R １ These are, independently, a hydrogen atom, -OH, and -SiR. ２ ３ Alternatively, a hydrocarbon group having 1 to 8 carbon atoms which may be substituted, R ２ Each of these is independently a hydrogen atom, or C １－６ The etching method according to any one of claims 1 to 4, wherein the reaction accelerator is a compound containing an alkyl group. [Clause 6] The etching method according to any one of claims 1 to 4, wherein the reaction accelerator is a compound containing -CN. [Clause 7] The etching method according to any one of claims 1 to 4, wherein the reaction accelerator is a compound containing -NCO. [Clause 8] The reaction accelerator is -NO２ The etching method according to any one of Items 1 to 4, which is a compound containing ２ , or N ２ O. [Item 9] The reaction accelerator is NO, NO ２ , or N ２ O. [Item 10] The etching gas contains at least one of NO, NO ３ -, and N １ ２ O, and in the etching gas, the partial pressure of any one of them is the largest. The etching method according to Item 9. [Item 11] The reaction accelerator is represented by the following formula (I): R １ -NR ２ ３ (I) [In the formula, R ２ are each independently a hydrogen atom, -OH, -SiR １－８ ３ ４ is each independently a hydrogen atom or a C ２ alkyl group, R ３ is a hydrogen atom, -OH, -SiR ２ ３ ４ ５ [[ID=​​​​​​​​​​​​​​​​​​​​​​​​​​​​​２ (II) [wherein, R １１ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group, R １２ C １－８ Alkylene group, C ３－８ Cycloalkylene group, or -R １３ -O-R １３ - and R １３ Each of them is independent of C １－８ The etching method according to any one of items 1 to 4, wherein the compound is represented by [an alkylene group]. [Item 13] The reaction accelerator is the following formula (III-1) or (III-2): R ２１ ２ N-R ２２ -NR ２１ -R ２２ -NR ２１ ２ (III-1) R ２１ ２ N-R ２３ (NR ２１ ２ ) - NR ２１ ２ (III-2) [wherein, R ２１ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group, R ２２ C １－８ It is an alkylene group, R ２３ The etching method according to any one of items 1 to 4, wherein the compound is represented by ]. [Item 14] The reaction accelerator is the following formula (IV): R ３１ ２ N-CO-NR ３１ ２ (IV) [wherein, R ３１ These are, independently, hydrogen atoms and C １－８ Alkyl alkyl group, or -OR ３２ And R ３２ is a hydrogen atom, or C １－８It is an alkyl group.] The etching method according to any one of items 1 to 4, which is a compound represented by [Item 15] The reaction accelerator is a cyclic amine. The etching method according to any one of items 1 to 4. [Item 16] The reaction accelerator is represented by the following formula (V): R ４１ -CN (V) [In the formula, R ４１ is a C １－８ alkyl group, a C ２－８ alkenyl group, or a C ２－８ alkynyl group, or -R ４２ -R ４３ and R ４２ is a single bond or a C １－８ alkylene group, R ４３ is -OH, -NR ４４ ２ , -OCO-R ４４ , or -SR ４４ and R ４４ are each independently a hydrogen atom or a C １－８ alkyl group.] The etching method according to any one of items 1 to 4, which is a compound represented by [Item 17] The reaction accelerator is represented by the following formula (VI): R ５１ -NCO (VI) [In the formula, R ５１ is a C １－８ alkyl group or -R ５２ -R ５３ ​​​​​​​​​​​​​​​​​​​​​The etching method according to any one of items 1 to 4, wherein the compound is represented by [an alkyl group]. [Item 19] The reaction accelerator is the following formula (VIII): R ７１ -N ３ (VIII) [wherein, R ７１ C １－８ Alkyl alkyl group, or -R ７２ -R ７３ And R ７２ is a single bond, or C １－８ It is an alkylene group, R ７３ is, -SiR ７４ ３ And R ７４ Each of these is independently a hydrogen atom, or C １－８ The etching method according to any one of items 1 to 4, wherein the compound is represented by [an alkyl group]. [Item 20] The reaction accelerator is the following formula (IX): R ８１ -N=C=N-R ８１ (IX) [wherein, R ８１ Each of them is independent of C １－８ The etching method according to any one of items 1 to 4, wherein the compound is represented by [an alkyl group]. [Item 21] The reaction accelerator is the following formula (X): R ９１ -ONO (X) [wherein, R ９１ Each of them is independent of C １－８ The etching method according to any one of items 1 to 4, wherein the compound is represented by [an alkyl group]. [Item 22] The reaction accelerator is the following formula (XI): R ９６ ２ C = N - R ９７ (XI) [wherein, R ９６ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group, R ９７ These are, independently, a hydrogen atom, an -OH group, or a C group. １－８The etching method according to any one of items 1 to 4, wherein the compound is represented by [an alkyl group]. [Item 23] The etching method according to any one of items 1 to 20, wherein the reaction accelerator is a compound that does not contain an oxygen atom. [Item 24] The etching method according to any one of items 1 to 4, wherein the reaction accelerator is selected from the following compounds: NO, NO ２ , N ２ O, NH ３ , [Clause 25] The etching method according to any one of Clauses 1 to 24, wherein the carbon film is a carbon film that serves as an etching mask in a subsequent process, is deposited at 300°C or higher, and may be doped with impurity atoms to increase etching resistance. [Clause 26] The etching method according to any one of Clauses 1 to 25, wherein the carbon film is an amorphous carbon film. [Clause 27] The etching method according to any one of Clauses 1 to 26, wherein the aspect ratio of the formed holes is 20 or more. [Clause 28] The etching method according to any one of Clauses 1 to 27, wherein the diameter of the formed holes is φ160 nm or less. [Clause 29] The etching method according to any one of Clauses 1 to 28, wherein the diameter of the formed holes is φ80 nm or less. [Clause 30] The etching method according to any one of Clauses 1 to 29, wherein the substrate temperature in step (2) is -10°C or lower. [Clause 31] The etching method according to any one of Clauses 1 to 30, wherein the supply temperature of the etching gas in step (2) is in the temperature range of 200°C or less. [Clause 32] The etching method according to any one of Clauses 1 to 31, wherein the pressure in the chamber in step (2) is 0.5 Pa to 15 Pa. [Clause 33] The etching method according to any one of Clauses 1 to 32, characterized in that the bias voltage applied to generate plasma is applied in a pulsed manner.

[0006] According to the method disclosed herein, the etching rate of carbon films is improved, and etching becomes more efficient.

[0007] As used herein, "hydrocarbon group" means a group containing carbon and hydrogen, from which one hydrogen atom has been removed from the molecule. Such hydrocarbon groups are not particularly limited, but include hydrocarbon groups having 1 to 6 carbon atoms, such as aliphatic hydrocarbon groups and aromatic hydrocarbon groups. The above-mentioned "aliphatic hydrocarbon group" may be linear, branched, or cyclic, and may be saturated or unsaturated. Furthermore, the hydrocarbon group may contain one or more ring structures. Such hydrocarbon groups may be substituted with one or more substituents. In addition, such hydrocarbon groups may have one or more N, O, S, Si, amide, sulfonyl, siloxane, carbonyl, carbonyloxy, etc., at their terminals or within their molecular chains.

[0008] In the use herein, the substituents of the "hydrocarbon group" are not particularly limited, but include, for example, halogen atoms; C which may be substituted with one or more halogen atoms. １－６ alkyl group, C ２－６ Alkenyl group, C ２－６ Alkynyl group, C ３－８ Cycloalkyl groups, C ３－８ Unsaturated cycloalkyl group, 5-8 membered heterocyclyl group, 5-8 membered unsaturated heterocyclyl group, C ６－８ Examples include one or more groups selected from aryl groups and 5- to 8-membered heteroaryl groups.

[0009] As used herein, “halogen atom” includes a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or an astatine atom. The halogen atom is preferably a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, more preferably a chlorine atom, a bromine atom, or an iodine atom.

[0010] The etching method of the present disclosure is a method for etching a carbon film, comprising: (1) providing a substrate having a carbon film in a chamber; and (2) etching the carbon film under plasma conditions using an etching gas containing a reaction accelerator, wherein the reaction accelerator contains N atoms.

[0011] Step (1) Provide a substrate having a carbon film into the chamber.

[0012] The substrate has a carbon film. In the etching method of this disclosure, the carbon film is etched.

[0013] The carbon film described above is preferably an amorphous carbon film.

[0014] The carbon film described above is preferably a film formed at a temperature of 300°C or higher.

[0015] The carbon film described above may be doped with impurity atoms to increase its etching resistance.

[0016] Examples of the impurity atoms mentioned above include W or B.

[0017] The content of impurity atoms in the carbon film described above may be, for example, 0 to 30% by mass, preferably 0 to 10% by mass, relative to the entire carbon film.

[0018] In one embodiment, the carbon film is doped with impurity atoms to increase etching resistance.

[0019] In one embodiment, the carbon film is not doped with impurity atoms to increase etching resistance.

[0020] The carbon film described above may exist on the substrate as a mask. For example, the carbon film can serve as an etching mask in a later process. Other layers, such as a silicon-containing film, may exist between the carbon film and the substrate.

[0021] The silicon-containing film described above may be a silicon oxide film or a silicon nitride film.

[0022] The carbon film described above may be masked. The mask is provided on the carbon film. The mask may be a metal-containing mask formed from a metal-containing material such as titanium nitride, tungsten, or tungsten carbide.

[0023] The mask on the carbon film described above is patterned; that is, the mask has a pattern that is transferred to the carbon film during the etching process.

[0024] The above-mentioned chamber provides a venue for performing etching. The chamber may be a general-purpose chamber typically used for etching, specifically a chamber for dry etching.

[0025] The size and material of the chamber are not particularly limited and can be appropriately selected according to the purpose.

[0026] Step (2) Etching the carbon film under plasma conditions using an etching gas containing oxygen and a reaction accelerator.

[0027] (Etching gas) The etching gas used in the etching method of this disclosure includes a reaction accelerator.

[0028] In one embodiment, the etching gas contains oxygen.

[0029] In one embodiment, the etching gas contains oxygen, and the partial pressure of oxygen is the highest in the etching gas; that is, the oxygen concentration is the highest.

[0030] In the etching gas, the oxygen concentration is preferably 50% by volume or more, more preferably 80% by volume or more, even more preferably 90% by volume or more, for example 95% by volume or more, 98% by volume or more, or 99% by volume or more. Alternatively, the oxygen concentration may be preferably 99.9% by volume or less, more preferably 99.8% by volume or less, for example 99.5% by volume or less, or 99% by volume or less.

[0031] The reaction accelerator described above is a compound that promotes etching. The etching gas of this disclosure, by containing the reaction accelerator, has an improved etching rate. Furthermore, it can suppress abnormal shapes of the formed patterns, such as grooves in wiring patterns and holes such as contact holes (e.g., bowing, distortion, twisting, etc.).

[0032] The reaction accelerator described above is preferably a compound containing an N atom (nitrogen atom). By using a compound containing an N atom, the etching rate can be improved and shape abnormalities can be suppressed.

[0033] The nitrogen atom content in the above-mentioned compound containing nitrogen atoms is preferably 5% or more, more preferably 10% or more, even more preferably 20% or more, even more preferably 30% or more, and particularly preferably 33% or more, for example, 40% or more or 45% or more, relative to the total number of atoms in the molecule. The upper limit of the nitrogen atom content is not particularly limited, but may be, for example, 80% or less or 60% or less. The etching rate can be further improved by including a large amount of nitrogen atoms.

[0034] The oxygen atom content of the above reaction accelerator is preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less, relative to the total number of atoms in the molecule, and is particularly preferable to not contain oxygen atoms.

[0035] The N atom in the above reaction accelerator may be contained in the main chain of the molecule, or it may be contained in a substituent of the main chain, for example, in a functional group.

[0036] In one embodiment, the reaction accelerator may be an inorganic compound, an amine compound, a diamine compound, a triamine compound, a urea compound, a cyclic amine compound, a nitrile compound, an isocyanate compound, a nitro compound, an azide compound, a carbodiimide compound, a nitrite compound, or an imine compound.

[0037] The above reaction accelerator is -NR １ ２ (In the formula, R １ These are, independently, a hydrogen atom, -OH, and -SiR. ２ ３ Alternatively, a hydrocarbon group having 1 to 8 carbon atoms which may be substituted, R ２ Each of these is independently a hydrogen atom, or C １－６ It is a compound containing an alkyl group.

[0038] The above reaction accelerator is a compound containing -CN.

[0039] The above reaction accelerator is a compound containing -NCO.

[0040] The above reaction accelerator is -NO ２ It is a compound containing [a specific compound].

[0041] The above inorganic compounds include, for example, NO, NO ２ , or N ２ It could be O.

[0042] In the above embodiment, preferably, the etching gas is NO, NO ２ and N ２ It contains at least one of O, and in etching gas, NO, NO ２ and N ２ The partial pressure of one of the O's is the largest. In one embodiment, the gases contained in the etching gas are NO, NO ２ and N ２ It is one of the following O types, preferably NO.

[0043] NO, NO in etching gas ２ and N ２ The total concentration of O is preferably 50% by volume or more, more preferably 80% by volume or more, even more preferably 90% by volume or more, for example, 95% by volume or more, 98% by volume or more, or 99% by volume or more. Also, NO, NO ２ and N ２ The total concentration of O is preferably 99.9% by volume or less, more preferably 99.8% by volume or less, for example, 99.5% by volume or less, or 99% by volume or less.

[0044] In etching gases, NO, NO ２ and N ２ O may be used alone or in a mixture with other components, such as oxygen.

[0045] The above amine compounds are, for example, those of the following formula (I): R ３ -NR １ ２ (I) [wherein, R １ These are, independently, a hydrogen atom, -OH, and -SiR. ２ ３or a hydrocarbon group having 1 to 8 carbon atoms, which may be substituted, R ２ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group, R ３ This consists of a hydrogen atom, -OH, and -SiR. ２ ３ , -R ４ -R ５ or a hydrocarbon group having 1 to 8 carbon atoms, which may be substituted, R ４ is a single bond, or C １－８ It is an alkylene group, R ５ C is a hydrogen atom. １－８ Alkyl alkyl group, -OR ６ , -OCOR ６ , -COR ６ ,-SR ６ -N=CR ６ ２ , -N ３ , or an oxetane group, R ６ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group. It is a compound represented by [ ].

[0046] R １ These are, independently, a hydrogen atom, -OH, and -SiR. ２ ３ or a hydrocarbon group having 1 to 8 carbon atoms, which may be substituted.

[0047] R １ The hydrocarbon group having 1 to 8 carbon atoms in this compound can be an alkyl group, an alkenyl group, an alkynyl group, or a cycloalkyl group. These groups may be linear or branched.

[0048] The substituents of the hydrocarbon group may include, for example, halogen atoms; C may be substituted with one or more halogen atoms. １－６ alkyl group, C ２－６ Alkenyl group, C ２－６ Alkynyl group, C ３－８ Examples include cycloalkyl groups, -OH groups, and =NOH groups.

[0049] R ２ Each of these is independently a hydrogen atom, or C１－８ It is an alkyl group.

[0050] R ２ The alkyl group in is preferably having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms, with a methyl group being particularly preferred. Such alkyl groups may be linear or branched.

[0051] R ３ This consists of a hydrogen atom, -OH, and -SiR. ２ ３ , -R ４ -R ５ or a hydrocarbon group having 1 to 8 carbon atoms, which may be substituted.

[0052] R ３ The C1-C8 hydrocarbon group in which the substituted group may be R １ This is equivalent to a hydrocarbon group having 1 to 8 carbon atoms in [the given context].

[0053] R ４ is a single bond, or C １－８ It is an alkylene group.

[0054] R ４ The alkylene group in the compound preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 4 carbon atoms, for example, 2 to 4 carbon atoms, 1 to 3 carbon atoms, or 1 to 2 carbon atoms. Such alkylene group may be linear or branched.

[0055] R ５ C is a hydrogen atom. １－８ Alkyl alkyl group, -OR ６ , -OCOR ６ , -COR ６ ,-SR ６ -N=CR ６ ２ , -N ３ , or an oxetane group.

[0056] R ５The alkyl group in is preferably having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms, with a methyl group being particularly preferred. Such alkyl groups may be linear or branched.

[0057] R ６ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group.

[0058] R ６ The alkyl group in is preferably having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms, with a methyl group being particularly preferred. Such alkyl groups may be linear or branched.

[0059] The oxetane group may have substituents. Examples of substituents include halogen atoms and C １－６ Examples include alkyl groups (preferably methyl groups). The oxetane group may be bonded at either the 2nd or 3rd position, and is preferably bonded at the 3rd position.

[0060] In one embodiment, the above amine compound is a primary amine compound. That is, R １ and R ３ Of these, two are hydrogen atoms and one is not a hydrogen atom. Preferably, R １ is a hydrogen atom, R ２ It is an atom other than a hydrogen atom.

[0061] In one embodiment, the above amine compound is a secondary amine compound. That is, R １ and R ３ Of these, one is a hydrogen atom and the other two are non-hydrogen atoms. Preferably, R １ One of them is a hydrogen atom, and the other is R １ and R ２ It is an atom other than a hydrogen atom.

[0062] In one embodiment, the above amine compound is a tertiary amine compound. That is, R １ and R ３ All of them are atoms other than hydrogen atoms.

[0063] In one embodiment, R １ and R ３ All of them may be hydrogen atoms. In this case, the compound is ammonia.

[0064] The above diamine compounds are, for example, those of the following formula (II): R １１ ２ N-R １２ -NR １１ ２ (II) [wherein, R １１ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group, R １２ C １－８ Alkylene group, C ３－８ Cycloalkylene group, or -R １３ -O-R １３ - and R １３ Each of them is independent of C １－８ It is an alkylene group. It is a compound represented by [ ].

[0065] R １１ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group.

[0066] R １１ The alkyl group in is preferably having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms, with a methyl group being particularly preferred. Such alkyl groups may be linear or branched.

[0067] In one embodiment, R １１ H is H.

[0068] In another embodiment, R １１ C １－８ An alkyl group, preferably a methyl group.

[0069] R １２ C １－８ Alkylene group, C ３－８ Cycloalkylene group, or -R １３ -O-R １３ - is the case.

[0070] R １２ The alkylene group in the compound preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 4 carbon atoms, for example, 2 to 4 carbon atoms, 1 to 3 carbon atoms, or 1 to 2 carbon atoms. Such alkylene group may be linear or branched.

[0071] R １２ C in ３－８ The cycloalkylene group may preferably have 3 to 8 carbon atoms, more preferably 3 to 6 carbon atoms, and even more preferably 3 to 4 carbon atoms.

[0072] R １３ Each of them is independent of C １－８ It is an alkylene group.

[0073] R １３ The alkylene group in the compound preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 4 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms. Such alkylene group may be linear or branched.

[0074] The above triamine compounds include, for example, those of the following formula (III-1) or (III-2): R ２１ ２ N-R ２２ -NR ２１ -R ２２ -NR ２１ ２ (III-1) R ２１ ２ N-R ２３ (NR ２１ ２ ) - NR ２１ ２ (III-2) [wherein, R ２１ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group, R ２２ C １－８ It is an alkylene group, R ２３ It is a compound represented by ], which is a trivalent hydrocarbon group.

[0075] R ２１ Each of these is independently a hydrogen atom, or C１－８ It is an alkyl group.

[0076] R ２１ The alkyl group in is preferably having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms, with a methyl group being particularly preferred. Such alkyl groups may be linear or branched.

[0077] In one embodiment, R ２１ H is H.

[0078] In another embodiment, R ２１ C １－８ An alkyl group, preferably a methyl group.

[0079] R ２２ C １－８ It is an alkylene group.

[0080] R ２２ The alkylene group in the compound preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 4 carbon atoms, for example, 2 to 4 carbon atoms, 1 to 3 carbon atoms, or 1 to 2 carbon atoms. Such alkylene group may be linear or branched.

[0081] R ２３ It is a trivalent hydrocarbon group.

[0082] R ２３ The trivalent hydrocarbon group in is preferably having 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 4 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms, with 1 carbon atom being particularly preferred.

[0083] R ２３ The trivalent hydrocarbon group in this compound may be saturated or unsaturated, and may be linear or branched. Preferably, the hydrocarbon group is a saturated hydrocarbon group.

[0084] The above urea-based compound is, for example, the following formula (IV): R ３１ ２ N-CO-NR ３１ ２ (IV) [wherein, R ３１These are, independently, hydrogen atoms and C １－８ Alkyl alkyl group, or -OR ３２ And R ３２ is a hydrogen atom, or C １－８ It is an alkyl group. It is a compound represented by [ ].

[0085] R ３１ These are, independently, hydrogen atoms and C １－８ Alkyl alkyl group, or -OR ３２ That is the case.

[0086] R ３１ The alkyl group in is preferably having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms, with a methyl group being particularly preferred. Such alkyl groups may be linear or branched.

[0087] R ３２ is a hydrogen atom, or C １－８ It is an alkyl group.

[0088] R ３２ The alkyl group in is preferably having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms, with a methyl group being particularly preferred. Such alkyl groups may be linear or branched.

[0089] In one embodiment, R bonded to the same N atom ３１ One of them is C １－８ The alkyl group is preferably a methyl group, and the other is -OR ３２ That is the case.

[0090] In another embodiment, R ３１ C １－８ An alkyl group, preferably a methyl group.

[0091] In another embodiment, R ３１ This is a hydrogen atom.

[0092] The above cyclic amine compounds may preferably have a 3- to 8-membered ring.

[0093] The above-mentioned cyclic amine compounds may be monocyclic or polycyclic. Monocyclic compounds are preferred.

[0094] The above cyclic amine compounds may contain 1 to 3 nitrogen atoms in the ring.

[0095] The above cyclic amine compounds may be substituted. The number of substituents is, for example, 1 to 6, preferably 1 to 3.

[0096] In one embodiment, the cyclic amine compound is unsubstituted.

[0097] In another embodiment, the above cyclic amine compound is substituted.

[0098] The substituents of the above cyclic amine compound may be, for example, halogen atoms; C may be substituted with one or more halogen atoms. １－６ alkyl group, C ２－６ Alkenyl group, C ２－６ Alkynyl group, C ３－８ Examples include cycloalkyl groups. The substituent is preferably a halogen atom or C １－６ Alkyl alkyl group, comfort C １－６ It may be an alkyl group (preferably a methyl group).

[0099] The above cyclic amine compounds may be saturated or unsaturated.

[0100] In one embodiment, the above-mentioned cyclic amine compound is saturated.

[0101] In another embodiment, the cyclic amine compound is unsaturated.

[0102] The above-mentioned cyclic amine compounds may contain atoms other than carbon and nitrogen atoms in the ring. They may contain 1 to 3 such atoms. Examples of these other atoms include oxygen atoms and sulfur atoms. The number of these other atoms is, for example, 1 to 3, preferably 1 to 2, and more preferably 1.

[0103] The above nitrile compounds are, for example, those of the following formula (V): R ４１ -CN (V) [wherein, R ４１C may be substituted with a halogen atom. １－８ alkyl group, C ２－８ Alkenyl group, or C ２－８ Alkynyl group, or -R ４２ -R ４３ And R ４２ is a single bond, or C １－８ It is an alkylene group, R ４３ -OH, -NR ４４ ２ , -OCO-R ４４ , or -SR ４４ And R ４４ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group. It is a compound represented by [ ].

[0104] R ４１ C may be substituted with a halogen atom. １－８ alkyl group, C ２－８ Alkenyl group, or C ２－８ Alkynyl group, or -R ４２ -R ４３ That is the case.

[0105] R ４１ Alkyl, C ２－８ Alkenyl group, and C ２－８ The alkynyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms. ２－８ Alkenyl group and C ２－８ For alkynyl groups, the lower limit of the number of carbon atoms is 2. These groups may be linear or branched.

[0106] R ４２ is a single bond, or C １－８ It is an alkylene group.

[0107] In one embodiment, R ４２ It is a single bond.

[0108] In another embodiment, R ４２ C １－８ It is an alkylene group.

[0109] R ４２ The alkylene group in the compound preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 4 carbon atoms, for example, 2 to 4 carbon atoms, 1 to 3 carbon atoms, or 1 to 2 carbon atoms. Such alkylene group may be linear or branched.

[0110] R ４３ -OH, -NR ４４ ２ , -OCO-R ４４ , or -SR ４４ That is the case.

[0111] R ４４ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group.

[0112] R ４４ The alkyl group in is preferably having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms, with a methyl group being particularly preferred. Such alkyl groups may be linear or branched.

[0113] The above isocyanate compounds are, for example, those of the following formula (VI): R ５１ -NCO (VI) [wherein, R ５１ C １－８ Alkyl alkyl group, or -R ５２ -R ５３ And R ５２ is a single bond, or C １－８ It is an alkylene group, R ５３ is, -SiR ５４ ３ And R ５４ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group. It is a compound represented by [ ].

[0114] R ５１ C １－８ Alkyl alkyl group, or -R ５２ -R ５３ That is the case.

[0115] R ５１The alkyl group in is preferably having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms, with a methyl group being particularly preferred. Such alkyl groups may be linear or branched.

[0116] R ５２ is a single bond, or C １－８ It is an alkylene group.

[0117] R ５２ The alkylene group in the compound preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 4 carbon atoms, for example, 2 to 4 carbon atoms, 1 to 3 carbon atoms, or 1 to 2 carbon atoms. Such alkylene group may be linear or branched.

[0118] In one embodiment, R ５２ It is a single bond.

[0119] In another embodiment, R ５２ C １－８ It is an alkylene group.

[0120] R ５４ Each of these is independently a hydrogen atom, or C １－８ Alkyl alkyl group, preferably C １－８ It is an alkyl group.

[0121] R ５４ The alkyl group in is preferably having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms, with a methyl group being particularly preferred. Such alkyl groups may be linear or branched.

[0122] In one embodiment, R ５４ C １－８ Alkyl alkyl group, preferably C １－３ An alkyl group, more preferably a methyl group.

[0123] The above nitro compounds are, for example, those of the following formula (VII): R ６１ - NO ２ (VII) [wherein, R ６１ C １－８It is an alkyl group. It is a compound represented by [ ].

[0124] R ６１ The alkyl group in is preferably having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms, with a methyl group being particularly preferred. Such alkyl groups may be linear or branched.

[0125] The above azide compounds are, for example, those of the following formula (VIII): R ７１ -N ３ (VIII) [wherein, R ７１ C １－８ Alkyl alkyl group, or -R ７２ -R ７３ And R ７２ is a single bond, or C １－８ It is an alkylene group, R ７３ is, -SiR ７４ ３ And R ７４ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group. It is a compound represented by [ ].

[0126] R ７１ C １－８ Alkyl alkyl group, or -R ７２ -R ７３ That is the case.

[0127] In one embodiment, R ７１ C １－８ It is an alkyl group.

[0128] In another embodiment, R ７１ is, -R ７２ -R ７３ That is the case.

[0129] R ７１ The alkyl group in is preferably having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms, with a methyl group being particularly preferred. Such alkyl groups may be linear or branched.

[0130] R ７２is a single bond, or C １－８ It is an alkylene group.

[0131] In one embodiment, R ７２ It is a single bond.

[0132] In another embodiment, R ７２ C １－８ It is an alkylene group.

[0133] R ７２ The alkylene group in the compound preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 4 carbon atoms, for example, 2 to 4 carbon atoms, 1 to 3 carbon atoms, or 1 to 2 carbon atoms. Such alkylene group may be linear or branched.

[0134] R ７３ is, -SiR ７４ ３ That is the case.

[0135] R ７４ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group.

[0136] R ７４ The alkyl group in is preferably having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms, with a methyl group being particularly preferred. Such alkyl groups may be linear or branched.

[0137] In one embodiment, R ７４ C １－８ Alkyl alkyl group, preferably C １－３ An alkyl group, more preferably a methyl group.

[0138] The above carbodiimide compounds are, for example, those of the following formula (IX): R ８１ -N=C=N-R ８１ (IX) [wherein, R ８１ Each of them is independent of C １－８ It is an alkyl group. It is a compound represented by [ ].

[0139] R ８１The alkyl group in the compound preferably has 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, for example, 2 to 6 carbon atoms, 1 to 4 carbon atoms, or 2 to 4 carbon atoms. Such alkyl groups may be linear or branched.

[0140] The above nitrite compounds are, for example, those of the following formula (X): R ９１ -ONO (X) [wherein, R ９１ Each of them is independent of C １－８ It is an alkyl group. It is a compound represented by [ ].

[0141] R ９１ The alkyl group in the compound preferably has 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, for example, 2 to 6 carbon atoms, 1 to 4 carbon atoms, or 2 to 4 carbon atoms. Such alkyl groups may be linear or branched.

[0142] The above imine compounds are, for example, those of the following formula (XI): R ９６ ２ C = N - R ９７ (XI) [wherein, R ９６ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group, R ９７ These are, independently, a hydrogen atom, an -OH group, or a C group. １－８ It is an alkyl group. It is a compound represented by [ ].

[0143] R ９６ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group.

[0144] R ９６ The alkyl group in is preferably having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms, with a methyl group being particularly preferred. Such alkyl groups may be linear or branched.

[0145] R ９７ These are, independently, a hydrogen atom, an -OH group, or a C group. １－８ It is an alkyl group.

[0146] In one embodiment, R９７ This is a hydrogen atom.

[0147] In another embodiment, R ９７ It is -OH.

[0148] In another embodiment, R ９７ is, -C １－８ It is an alkyl group.

[0149] R ９７ The alkyl group in is preferably having 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and even more preferably 1 to 3 carbon atoms, for example, 2 to 4 carbon atoms or 1 to 2 carbon atoms, with a methyl group being particularly preferred. Such alkyl groups may be linear or branched.

[0150] Examples of compounds containing the above-mentioned N atom include the following compounds: NO, NO ２ , N ２ O, NH ３ ,

[0151] In a preferred embodiment, the compound containing the above N atom is NO, NO ２ It may be dimethylamine or diethylamine.

[0152] The etching gas may be diluted with an inert gas as needed.

[0153] Examples of inert gases include noble gases and nitrogen. Examples of noble gases include helium, neon, argon, xenon, and krypton. These inert gases can be used individually or in combination of two or more. Furthermore, these inert gases can be known or commercially available.

[0154] When diluting etching gas with an inert gas, the amount of inert gas may be, for example, 0.1 to 10 volume percent of the total amount of etching gas.

[0155] The flow rate of the etching gas in step (2) is preferably 5 to 2000 sccm, more preferably 10 to 1000 sccm. If the etching gas is diluted with an inert gas, this flow rate is the flow rate of the mixture of the etching gas and the inert gas.

[0156] The supply temperature of the etching gas in step (2) is preferably 200°C or lower, more preferably 150°C or lower, and even more preferably 100°C or lower.

[0157] The substrate temperature in step (2) is preferably 50°C or lower, more preferably 30°C or lower, even more preferably 10°C or lower, even more preferably 0°C or lower, and particularly preferably -10°C or lower. The substrate temperature in step (2) is, for example, -50°C or higher or -30°C or higher.

[0158] The pressure inside the chamber during step (2) is between 0.5 Pa and 15 Pa.

[0159] The discharge power in step (2) is preferably 200 to 20,000 W, more preferably 400 to 10,000 W.

[0160] The bias power in step (2) is preferably 25 to 15,000 W, more preferably 100 to 10,000 W.

[0161] The bias power in step (2) is preferably applied in a pulsed manner.

[0162] The electron density in step (2) is preferably 10 ９ ~10 １３ cm －３ , more preferably 10 １０ ~10 １２ cm －３ It is possible.

[0163] The electron temperature in step (2) is preferably 2 to 9 eV, more preferably 3 to 8 eV.

[0164] Since the etching method of this disclosure can achieve a high etching rate, the patterns formed can be fine.

[0165] The aspect ratio of the pattern formed by the etching method of this disclosure may preferably be 20 or more, more preferably 30 or more, even more preferably 40 or more, and even more preferably 50 or more. The pattern is preferably a hole, particularly a contact hole. Here, the aspect ratio is the ratio of the depth to the width (or diameter) of the formed pattern.

[0166] The width or diameter of the pattern formed by the etching method of this disclosure may preferably be φ160 nm or less, more preferably φ120 nm or less, even more preferably φ80 nm or less, and even more preferably φ50 nm or less. The pattern may preferably be holes, particularly contact holes.

[0167] The present invention will be described in detail below using examples, but the present invention is not limited to these examples.

[0168] <Examples 1-9 and Comparative Examples 1-2> Each gas was introduced into an ICP (Inductively Coupled Plasma) plasma apparatus at the flow rates (sccm) shown in Table 1. The process pressure was maintained at 35 mTorr using a pressure regulating valve, and plasma was generated with a high-frequency power of 13.56 MHz and 2700 W. A bias power of 400 kHz and 1000 W was applied to draw ions into the film to be etched. Etching was performed for 60 seconds at an ESC temperature (chuck temperature) of -10°C under the following conditions, and the etching rate (ER) was measured. A carbon film was used as the film to be etched. The results are shown in Table 1.

[0169] Note that in Table 1, C ２ H ７ N represents dimethylamine, C ４ H １１ N represents diethylamine.

[0170]

[0171] <Examples 10-14 and Comparative Examples 3-4> Each gas was introduced into an ICP (Inductively Coupled Plasma) plasma apparatus at the flow rates (sccm) shown in Table 2. The process pressure was maintained at 35 mTorr using a pressure regulating valve. Plasma was generated with a high-frequency power of 13.56 MHz and 2700 W, and a bias power of 400 kHz and 1000 W was applied to draw ions into the film to be etched. Etching was performed for 60 seconds at an ESC temperature (chuck temperature) of -10°C under the following conditions, and the etching rate (ER) was measured. A carbon film patterned with an SiON film as an etching mask was used as the film to be etched. The results are shown in Table 2.

[0172] Note that in Table 2, C ２ H ７ N represents dimethylamine, C ４ H １１ N represents diethylamine.

[0173]

[0174] The etching method of this disclosure is suitably used for etching substrates having a carbon film.

Claims

1. A method for etching a carbon film, comprising: (1) providing a substrate having a carbon film in a chamber; and (2) etching the carbon film under plasma conditions using an etching gas containing a reaction accelerator, wherein the reaction accelerator contains N atoms.

2. The etching method according to claim 1, wherein the etching gas further contains oxygen, and the partial pressure of oxygen is the largest in the etching gas.

3. The etching method according to claim 1 or 2, wherein the reaction accelerator is a compound containing 5% or more N atoms relative to the total number of atoms.

4. The etching method according to any one of claims 1 to 3, wherein the reaction accelerator is a compound containing 33% or more N atoms relative to the total number of atoms.

5. The reaction accelerator is -NR １ ２ (In the formula, R １ These are, independently, a hydrogen atom, -OH, and -SiR. ２ ３ Alternatively, a hydrocarbon group having 1 to 8 carbon atoms which may be substituted, R ２ Each of these is independently a hydrogen atom, or C １－６ The etching method according to any one of claims 1 to 4, wherein the compound is an alkyl group.

6. The etching method according to any one of claims 1 to 4, wherein the reaction accelerator is a compound containing -CN.

7. The etching method according to any one of claims 1 to 4, wherein the reaction accelerator is a compound containing -NCO.

8. The reaction accelerator is -NO ２ The etching method according to any one of claims 1 to 4, wherein the compound is a compound containing the following.

9. The reaction accelerator is NO, NO ２ , or N ２ O. The etching method according to any one of claims 1 to 4.

10. The etching gas is NO, NO ２ , and N ２ The etching method according to claim 9, wherein the etching gas contains at least one of O, and the partial pressure of any one of them is the largest.

11. The reaction accelerator is given by the following formula (I): R ３ -NR １ ２ (I) [wherein, R １ These are, independently, a hydrogen atom, -OH, and -SiR. ２ ３ or a hydrocarbon group having 1 to 8 carbon atoms, which may be substituted, R ２ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group, R ３ This consists of a hydrogen atom, -OH, and -SiR. ２ ３ , -R ４ -R ５ or a hydrocarbon group having 1 to 8 carbon atoms, which may be substituted, R ４ is a single bond, or C １－８ It is an alkylene group, R ５ C is a hydrogen atom. １－８ Alkyl alkyl group, -OR ６ , -OCOR ６ , -COR ６ ,-SR ６ -N=CR ６ ２ , -N ３ , or an oxetane group, R ６ Each of these is independently a hydrogen atom, or C １－８ The etching method according to any one of claims 1 to 4, wherein the compound is represented by ] which is an alkyl group.

12. The reaction accelerator is given by the following formula (II): R １１ 2N-R １２ -NR １１ 2 (II) [wherein, R １１ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group, R １２ C １－８ Alkylene group, C ３－８ Cycloalkylene group, or -R １３ -O-R １３ - and R １３ Each of them is independent of C １－８ The etching method according to any one of claims 1 to 4, wherein the compound is represented by [an alkylene group].

13. The reaction accelerator is the following formula (III-1) or (III-2): R ２１ ２ N-R ２２ -NR ２１ -R ２２ -NR ２１ ２ (III-1) R ２１ ２ N-R ２３ (NR ２１ ２ ) - NR ２１ ２ (III-2) [wherein, R ２１ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group, R ２２ C １－８ It is an alkylene group, R ２３ The etching method according to any one of claims 1 to 4, wherein the compound is represented by ], where is a trivalent hydrocarbon group.

14. The reaction accelerator is given by the following formula (IV): R ３１ ２ N-CO-NR ３１ ２ (IV) [wherein, R ３１ These are, independently, hydrogen atoms and C １－８ Alkyl alkyl group, or -OR ３２ And R ３２ is a hydrogen atom, or C １－８ The etching method according to any one of claims 1 to 4, wherein the compound is represented by ] which is an alkyl group.

15. The etching method according to any one of claims 1 to 4, wherein the reaction accelerator is a cyclic amine.

16. The reaction accelerator is represented by the following formula (V): R ４１ -CN (V) [In the formula, R ４１ may be substituted by a halogen atom, and is a C １－８ alkyl group, a C ２－８ alkenyl group, or a C ２－８ alkynyl group, or -R ４２ -R ４３ ; R ４２ is a single bond or a C １－８ alkylene group; R ４３ is -OH, -NR ４４ ２ , -OCO-R ４４ , or -SR ４４ ; and R ４４ are each independently a hydrogen atom or a C １－８ alkyl group.]. The etching method according to any one of claims 1 to 4, which is a compound represented by the above formula.

17. The reaction accelerator is represented by the following formula (VI): R ５１ -NCO (VI) [In the formula, R ５１ is a C １－８ alkyl group, or -R ５２ -R ５３ where R ５２ is a single bond or a C １－８ alkylene group, and R ５３ is -SiR s ５４ ３ where R ５４ are each independently a hydrogen atom or a C １－８ alkyl group.]. The etching method according to any one of claims 1 to 4, which is a compound represented by the formula.

18. The reaction accelerator is given by the following formula (VII): R ６１ - NO ２ (VII) [wherein, R ６１ C １－８ The etching method according to any one of claims 1 to 4, wherein the compound is represented by ] which is an alkyl group.

19. The reaction accelerator is given by the following formula (VIII): R ７１ -N ３ (VIII) [wherein, R ７１ C １－８ Alkyl alkyl group, or -R ７２ -R ７３ And R ７２ is a single bond, or C １－８ It is an alkylene group, R ７３ is, -SiR ７４ ３ And R ７４ Each of these is independently a hydrogen atom, or C １－８ The etching method according to any one of claims 1 to 4, wherein the compound is represented by ] which is an alkyl group.

20. The reaction accelerator is given by the following formula (IX): R ８１ -N=C=N-R ８１ (IX) [wherein, R ８１ Each of them is independent of C １－８ The etching method according to any one of claims 1 to 4, wherein the compound is represented by ] which is an alkyl group.

21. The reaction accelerator is given by the following formula (X): R ９１ -ONO (X) [wherein, R ９１ Each of them is independent of C １－８ The etching method according to any one of claims 1 to 4, wherein the compound is represented by ] which is an alkyl group.

22. The reaction accelerator is given by the following formula (XI): R ９６ ２ C = N - R ９７ (XI) [wherein, R ９６ Each of these is independently a hydrogen atom, or C １－８ It is an alkyl group, R ９７ These are, independently, a hydrogen atom, an -OH group, or a C group. １－８ The etching method according to any one of claims 1 to 4, wherein the compound is represented by ] which is an alkyl group.

23. The etching method according to any one of claims 1 to 20, wherein the reaction accelerator is a compound that does not contain oxygen atoms.

24. The etching method according to any one of claims 1 to 4, wherein the reaction accelerator is selected from the following compounds: NO, NO ２ , N ２ O, NH ３ , 25. The etching method according to any one of claims 1 to 24, wherein the carbon film is a carbon film that serves as an etching mask in a subsequent process, is formed at a temperature of 300°C or higher, and may be doped with impurity atoms to increase etching resistance.

26. The etching method according to any one of claims 1 to 25, wherein the carbon film is an amorphous carbon film.

27. The etching method according to any one of claims 1 to 26, wherein the aspect ratio of the formed holes is 20 or more.

28. The etching method according to any one of claims 1 to 27, wherein the diameter of the formed hole is φ160 nm or less.

29. The etching method according to any one of claims 1 to 28, wherein the diameter of the hole formed is φ80 nm or less.

30. The etching method according to any one of claims 1 to 29, wherein the substrate temperature in step (2) is -10°C or lower.

31. The etching method according to any one of claims 1 to 30, wherein the supply temperature of the etching gas in step (2) is in the temperature range of 200°C or less.

32. The etching method according to any one of claims 1 to 31, wherein the pressure inside the chamber in step (2) is 0.5 Pa to 15 Pa.

33. The etching method according to any one of claims 1 to 32, characterized in that the bias voltage applied to generate plasma is applied in a pulsed manner.

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