Etching method

Abstract

The present invention provides an etching method for a silicon-containing film, the etching method comprising: (1) providing a substrate having a silicon-containing film in a chamber; and (2) etching the silicon-containing film under plasma conditions using an etching gas containing hydrogen fluoride and a reaction accelerator, wherein, in the etching gas, the partial pressure of the hydrogen fluoride is the highest.

Description

Etching Method

[0001] The present disclosure relates to an etching method.

[0002] As a method for enabling efficient etching, a method using an etching gas containing a phosphorus-containing gas, a fluorine-containing gas, and hydrogen fluoride is known (Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2023-067527

[0004] The present disclosure aims to provide a more efficient etching method.

[0005] The present disclosure includes the following aspects. [Item 1] A method for etching a silicon-containing film, comprising: (1) providing a substrate having a silicon-containing film in a chamber; and (2) etching the silicon-containing film under plasma conditions using an etching gas containing hydrogen fluoride and a reaction accelerator, wherein the partial pressure of hydrogen fluoride is the highest in the etching gas. [Item 2] The etching method according to Item 1, wherein the reaction accelerator contains a compound having a fluorine atom. [Item 3] The etching method according to Item 1 or 2, wherein the reaction accelerator contains a compound having a structure selected from —OH, —CHO, —COOH, —C—O—C—, and —CO—. [Item 4] The etching method according to Item 3, wherein the compound having an —OH group has a boiling point of 100° C. or lower at 0.1 MPa. [Item 5] The etching method according to Item 3, wherein the compound having an —OH group has a boiling point of 96° C. or lower at 0.1 MPa. [Item 6] The etching method according to Item 3, wherein the compound having an —OH group has a boiling point of 85° C. or lower at 0.1 MPa. [Item 7] The etching method according to Item 3, wherein the compound having —OH has a boiling point of 60° C. or less at 0.1 MPa. [Item 8] The compound having —OH is a compound represented by the following formula: １ａ -R １ｂ -R １ｃ -OH HO-R １ｂ -OH [wherein, R １ａ is a hydrogen atom, a fluorine atom, or —NH ２ and R １ｂis an alkylene group optionally substituted by a fluorine atom, R １ｃ is a single bond or -SO ２ Item 9. The etching method according to Item 3, wherein R is a compound represented by the formula: １ａ is a hydrogen atom or a fluorine atom, R １ｂ is an alkylene group having 1 to 4 carbon atoms which may be substituted with a fluorine atom, R １ｃ Item 10. The etching method according to Item 8, wherein R is a single bond. １ａ is a hydrogen atom, and R １ｂ is an alkylene group having 1 to 2 carbon atoms, and R １ｃ Item 11. The etching method according to Item 8 or 9, wherein R is a single bond. １ａ is a hydrogen atom or a fluorine atom, R １ｂ is a fluorinated alkylene group having 1 to 4 carbon atoms and substituted with a fluorine atom, R １ｃ [Item 12] The etching method according to any one of items 8 to 10, wherein the compound containing —CHO is a compound represented by the following formula: R ２ａ -R ２ｂ -CHO [wherein, R ２ａ is a hydrogen atom, a fluorine atom or —OH, R ２ｂ [Item 13] R is a single bond or an alkylene group optionally substituted with a fluorine atom. ２ａ is a hydrogen atom or a fluorine atom, R ２ｂ Item 14. The etching method according to Item 13, wherein R is a single bond or an alkylene group having 1 carbon atom which may be substituted with a fluorine atom. [Item 14] The compound containing —COOH is a compound represented by the following formula: ３ａ -R ３ｂ -R ３ｃ -COOH [wherein, R ３ａ is a hydrogen atom or a fluorine atom, R ３ｂ is a single bond or an alkylene group optionally substituted with a fluorine atom, R ３ｃ is a single bond or -SO ２Item 15. The etching method according to Item 3, wherein R is a compound represented by the formula: ３ａ is a hydrogen atom or a fluorine atom, R ３ｂ is a single bond or an alkylene group having 1 carbon atom which may be substituted with a fluorine atom, R ３ｃ Item 16: The etching method according to Item 14, wherein the compound containing —CO— is a compound represented by the following formula: ４ａ -R ４ｂ -CO-R ４ｃ -R ４ｄ [In the formula, R ４ａ is a hydrogen atom, a fluorine atom, or an alkyl group optionally substituted by a fluorine atom, and R ４ｂ is a single bond or a group containing at least one group selected from an unsaturated alkylene group optionally substituted with an oxygen atom and a fluorine atom, and R ４ｃ is a single bond or -SO ２ - and R ４ｄ [Item 17] R is a hydrogen atom, a fluorine atom, or an alkyl group optionally substituted with a fluorine atom. ４ａ is a hydrogen atom, a fluorine atom, or an alkyl group optionally substituted by a fluorine atom, and R ４ｂ is a single bond, or —CF═CH—, —O—CH═CH—, and R ４ｃ is a single bond, R ４ｄ Item 18: The etching method according to Item 16, wherein R is a hydrogen atom, a fluorine atom, or an alkyl group substituted with a fluorine atom. [Item 18] The compound containing —O— is a compound represented by the following formula: ５ａ -R ５ｂ -O-R ５ｃ -R ５ｄ [In the formula, R ５ａ is an alkyl or alkenyl group optionally substituted with a fluorine atom or a chlorine atom, R ５ｂ is a single bond or —CO—, R ５ｃ is a single bond or —CO—, R ５ｄ[Item 19] R is an alkyl group or an alkenyl group optionally substituted with a fluorine atom or a chlorine atom. ５ａ is an alkyl group optionally substituted with a fluorine atom or a chlorine atom, R ５ｂ is a single bond, R ５ｃ is a single bond, R ５ｄ [Item 20] The etching method according to Item 18, wherein the compound containing —O— is a compound represented by the following formula: [In the formula, R ６ are each independently a hydrogen atom or a fluorine atom, ７ are each independently a hydrogen atom, a fluorine atom, or an alkyl group optionally substituted with a fluorine atom, and n is an integer of 1 to 4. Item 21: The etching method according to any one of Items 1 to 20, wherein the aspect ratio of the processed shape to be formed is 50 or more. Item 22: The etching method according to any one of Items 1 to 21, wherein the supply temperature of the etching gas in step (2) is 90°C or less. Item 23: The etching method according to any one of Items 1 to 22, wherein the reaction accelerator contains a compound having a boiling point of 90°C or less at 0.1 MPa. Item 24: The etching method according to any one of Items 1 to 23, wherein the reaction accelerator contains a compound having a boiling point of 65°C or less at 0.1 MPa. Item 25: The etching method according to any one of Items 1 to 24, wherein the substrate temperature in step (2) is 20°C or less. [Item 26] The etching method according to any one of Items 1 to 25, wherein the pressure in the chamber in step (2) is 0.5 Pa to 15 Pa.

[0006] According to the method of the present disclosure, the etching rate is improved, and etching can be performed efficiently.

[0007] Fig. 1 is an SEM image of the film before etching in Example 11. Fig. 2 is an SEM image of the film after etching in Example 11. Fig. 3 is an SEM image of the film after etching in Comparative Example 3.

[0008] The etching method of the present disclosure is a method for etching a silicon-containing film, comprising: (1) providing a substrate having a silicon-containing film in a chamber; and (2) etching the silicon-containing film under plasma conditions using an etching gas containing hydrogen fluoride and a reaction accelerator, wherein the partial pressure of hydrogen fluoride in the etching gas is the highest.

[0009] Step (1) providing a substrate having a silicon-containing film in a chamber

[0010] The substrate has a silicon-containing film, and the silicon-containing film is etched in the etching method of the present disclosure.

[0011] The silicon-containing film includes a silicon oxide film or a silicon nitride film.

[0012] In one embodiment, the silicon-containing film is a silicon oxide film.

[0013] In one embodiment, the silicon-containing film is a silicon nitride film.

[0014] The substrate may include a mask disposed on the silicon-containing film. The mask may be, for example, an amorphous carbon film, a photoresist film, or a spin-on carbon film. The mask may be a metal-containing mask formed from a metal-containing material such as titanium nitride, tungsten, or tungsten carbide.

[0015] The mask MK is patterned, i.e., it has a pattern that is transferred to the silicon-containing film during the etching step.

[0016] The chamber provides a place for performing etching, and may be a general chamber typically used for etching, specifically a chamber for dry etching.

[0017] The size, material, etc. of the chamber are not particularly limited and can be selected appropriately depending on the purpose.

[0018] Step (2) etching the silicon-containing film under plasma conditions using an etching gas containing hydrogen fluoride and a reaction accelerator.

[0019] (Etching Gas) The etching gas used in the etching method of the present disclosure contains hydrogen fluoride, and the partial pressure of hydrogen fluoride is the highest.

[0020] The concentration of hydrogen fluoride in the etching gas is preferably 10% by volume or more, more preferably 20% by volume or more, and even more preferably 30% by volume or more, for example, 40% by volume or more, 50% by volume or more, or 60% by volume or more. The concentration of hydrogen fluoride is preferably 90% by volume or less, more preferably 80% by volume or less, for example, 70% by volume or less, 60% by volume or less, or 50% by volume or less.

[0021] The reaction accelerator is a compound that accelerates etching. By including the reaction accelerator in the etching gas of the present disclosure, the etching rate is improved.

[0022] The reaction accelerator is preferably a compound containing fluorine atoms. By using a compound containing fluorine atoms, fluorine dissociated in the plasma accelerates etching, thereby improving the etching rate.

[0023] The fluorine atom content in the fluorine atom-containing compound is preferably 15 atomic % or more, more preferably 30 atomic % or more, even more preferably 40 atomic % or more, still more preferably 50 atomic % or more, for example, 60 atomic % or more. The upper limit of the fluorine atom content is not particularly limited, but may be, for example, 90 atomic % or less or 80 atomic % or less.

[0024] The reaction accelerator preferably contains a compound having a structure selected from -OH, -CHO, -COOH, -C-O-C- and -CO-. When the reaction accelerator has such a structure, H ２The present invention is not limited to a theory, but when the silicon-containing film is a silicon oxide film or a silicon nitride film, the following mechanism is considered. Oxide film: SiO ２ +4HF+H ２ O → SiF ４ ↑+3H ２ O nitride film: Si ３ N ４ +16HF→2(NH ４ ) ２ SiF ６ +SiF ４ (1) (NH ４ ) ２ SiF ６ →2NH ３ ↑+SiF ４ ↑+2HF+H ２ O (2) Although the present disclosure is not bound by theory, it is generally believed that the (NH ４ ) ２ SiF ６ It is thought that (NH ４ ) ２ SiF ６ In order to volatilize (NH), heating is required. However, in the present invention, water generated in the plasma acts as a catalyst, and (NH ４ ) ２ SiF ６ It is believed that the etching rate is improved by promoting the decomposition reaction of

[0025] The compound containing —OH may be a compound having a boiling point at 0.1 MPa of preferably 100° C. or lower, more preferably 96° C. or lower, even more preferably 85° C. or lower, still more preferably 60° C. or lower, and particularly preferably 50° C. or lower. The lower limit of the boiling point is not particularly limited, but may be, for example, −50° C. or higher or −30° C. or higher.

[0026] The compound containing —OH is preferably represented by the following formula: １ａ -R １ｂ -R １ｃ -OH HO-R １ｂ -OH [wherein, R １ａis a hydrogen atom, a fluorine atom, or —NH ２ and R １ｂ is an alkylene group optionally substituted by a fluorine atom, R １ｃ is a single bond or -SO ２ - is a compound represented by the formula:

[0027] In one embodiment, the compound containing —OH is R １ａ -R １ｂ -R １ｃ It is —OH.

[0028] In another embodiment, the compound containing —OH is HO—R １ｂ It is —OH.

[0029] In one embodiment, R １ａ is a hydrogen atom or a fluorine atom.

[0030] In one embodiment, R １ａ is a hydrogen atom.

[0031] In another embodiment, R １ａ is a fluorine atom.

[0032] In another embodiment, R １ａ is -NH ２ is.

[0033] R １ｂ The alkylene group optionally substituted with a fluorine atom 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, 1 to 3 or 1 to 2 carbon atoms. Such an alkylene group may be linear or branched.

[0034] In one embodiment, R １ｂ is an alkylene group substituted with a fluorine atom.

[0035] In another embodiment, R １ｂ is an unsubstituted alkylene group.

[0036] In one embodiment, R １ｃ is a single bond.

[0037] In another embodiment, R １ｃ is -SO２ - is.

[0038] In a preferred embodiment, R １ａ is a hydrogen atom or a fluorine atom, R １ｂ is an alkylene group having 1 to 4 carbon atoms which may be substituted with a fluorine atom, R １ｃ is a single bond.

[0039] In a preferred embodiment, R １ａ is a hydrogen atom, and R １ｂ is an alkylene group having 1 to 2 carbon atoms, and R １ｃ is a single bond.

[0040] In a preferred embodiment, R １ａ is a hydrogen atom or a fluorine atom, R １ｂ is a fluorinated alkylene group having 1 to 4 carbon atoms and substituted with a fluorine atom, R １ｃ is a single bond.

[0041] Examples of compounds containing —OH include methanol, ethanol, propanol (n-propyl alcohol, isopropyl alcohol), butyl alcohol (n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol), 2,2-difluoroethanol, 2,2,2-trifluoroethanol, 3-fluoropropanol, 2,2,3,3-tetrafluoropropanol, 3,3,3-trifluoropropanol, 2,2,3,3,3-pentafluoropropanol, 1,1,1,3,3,3-hexafluoroisopropyl alcohol, 4,4,4-trifluoro-1-butanol, perfluoro-tert-butyl alcohol, 2-trifluoromethyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2 -propanol, ethylene glycol, 1,2-propanediol, 2,2,3,3-tetrafluoro-1,4-butanediol, ethanolamine, trifluoromethanesulfonic acid, fluorosulfonic acid, perfluoro-tert-butyl alcohol, 1,1,1,3,3,3-hexafluoroisopropyl alcohol, 2,2,2-trifluoroethanol, 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, methanol, ethanol, 2,2,3,3,3-pentafluoropropanol, or 2-trifluoromethyl-2-propanol is preferred, and perfluoro-tert-butyl alcohol, 1,1,1,3,3,3-hexafluoroisopropyl alcohol, 2,2,2-trifluoroethanol, or ethanol is more preferred.

[0042] The compound containing —CHO is preferably represented by the following formula: ２ａ -R ２ｂ -CHO [wherein, R ２ａ is a hydrogen atom, a fluorine atom or —OH, R ２ｂ is a single bond or an alkylene group which may be substituted with a fluorine atom.

[0043] In one embodiment, R ２ａ is a hydrogen atom or a fluorine atom.

[0044] In one embodiment, R ２ａ is a hydrogen atom.

[0045] In another embodiment, R ２ａ is a fluorine atom.

[0046] In another embodiment, R ２ａ is —OH.

[0047] R ２ｂ The alkylene group optionally substituted with a fluorine atom 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, 1 to 3, 1 to 2, or 1 carbon atom. Such an alkylene group may be linear or branched.

[0048] In one embodiment, R ２ｂ is an alkylene group substituted with a fluorine atom.

[0049] In another embodiment, R ２ｂ is an unsubstituted alkylene group.

[0050] In a preferred embodiment, R ２ａ is a hydrogen atom or a fluorine atom, R ２ｂ represents a single bond or an alkylene group having 1 carbon atom which may be substituted with a fluorine atom,

[0051] Examples of compounds containing —CHO include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, 2,2,2-trifluoroacetaldehyde, F—CHO, and CF ３ CF ２ -CHO, CF ３ CF ２ CF ２ CF ２ -CHO is an example.

[0052] The compound containing —COOH is preferably represented by the following formula: ３ａ -R ３ｂ -R ３ｃ -COOH [wherein, R ３ａ is a hydrogen atom or a fluorine atom, R ３ｂis a single bond or an alkylene group optionally substituted with a fluorine atom, R ３ｃ is a single bond or -SO ２ - is a compound represented by the formula:

[0053] In one embodiment, R ３ａ is a hydrogen atom.

[0054] In another embodiment, R ３ａ is a fluorine atom.

[0055] R ３ｂ The alkylene group optionally substituted with a fluorine atom 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, 1 to 3, 1 to 2, or 1 carbon atom. Such an alkylene group may be linear or branched.

[0056] In one embodiment, R ３ｂ is an alkylene group substituted with a fluorine atom.

[0057] In another embodiment, R ３ｂ is an unsubstituted alkylene group.

[0058] In one embodiment, R ３ｃ is a single bond.

[0059] In another embodiment, R ３ｃ is -SO ２ - is.

[0060] In a preferred embodiment, R ３ａ is a hydrogen atom or a fluorine atom, R ３ｂ is a single bond or an alkylene group having 1 carbon atom which may be substituted with a fluorine atom, R ３ｃ is a single bond.

[0061] The compound containing —COOH may be, for example, formic acid, acetic acid, butyric acid, or valeric acid.

[0062] The compound containing —CO— is preferably represented by the following formula: ４ａ -R ４ｂ -CO-R ４ｃ -R４ｄ [In the formula, R ４ａ is a hydrogen atom, a fluorine atom, or an alkyl group optionally substituted by a fluorine atom, and R ４ｂ is a single bond or a group containing at least one group selected from an unsaturated alkylene group optionally substituted with an oxygen atom and a fluorine atom, and R ４ｃ is a single bond or -SO ２ - and R ４ｄ is a hydrogen atom, a fluorine atom, or an alkyl group which may be substituted with a fluorine atom.

[0063] R ４ａ and R ４ｄ The alkyl group optionally substituted with a fluorine atom in the formula (I) 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, 1 to 3 or 1 to 2 carbon atoms. Such an alkyl group may be linear or branched.

[0064] In one embodiment, R ４ａ is a hydrogen atom.

[0065] In another embodiment, R ４ａ is a fluorine atom.

[0066] In another embodiment, R ４ａ is an alkyl group substituted with a fluorine atom.

[0067] In another embodiment, R ４ａ is an unsubstituted alkyl group.

[0068] In one embodiment, R ４ｄ is a hydrogen atom.

[0069] In another embodiment, R ４ｄ is a fluorine atom.

[0070] In another embodiment, R ４ｄ is an alkyl group substituted with a fluorine atom.

[0071] In another embodiment, R ４ｄ is an unsubstituted alkyl group.

[0072] R ４ｂ The alkylene group optionally substituted with a fluorine atom 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, 1 to 3 or 1 to 2 carbon atoms. Such an alkylene group may be linear or branched.

[0073] In one embodiment, the alkylene group optionally substituted with a fluorine atom is an alkylene group substituted with a fluorine atom.

[0074] In another embodiment, the alkylene group optionally substituted with a fluorine atom is an unsubstituted alkylene group.

[0075] In one embodiment, R ４ｂ is a single bond.

[0076] In one embodiment, R ４ｂ is -CH=CF- or -O-CH=CH-. Here, the left side is R ４ａ Combine with.

[0077] In one embodiment, R ４ｃ is a single bond.

[0078] In another embodiment, R ４ｃ is -SO ２ - is.

[0079] In a preferred embodiment, R ４ａ is an alkyl group optionally substituted with a fluorine atom, R ４ｂ is a single bond or —O—CH═CH—, and R ４ｃ is a single bond, R ４ｄ is an alkyl group substituted with a fluorine atom.

[0080] As the compound containing —CO—, for example, the following compound is used: O═CF ２ CF ３ CF ２ -C(=O)-F CF ３ -C(=O)-CF ３ CH ２ =CF-C(=O)-F

[0081] The compound containing —O— is preferably represented by the following formula: ５ａ -R ５ｂ -O-R ５ｃ -R ５ｄ [In the formula, R ５ａ is an alkyl or alkenyl group optionally substituted with a fluorine atom or a chlorine atom, R ５ｂ is a single bond or —CO—, R ５ｃ is a single bond or —CO—, R ５ｄ is an alkyl or alkenyl group which may be substituted with a fluorine atom or a chlorine atom.] Here, —O— is preferably an ethereal oxygen atom.

[0082] R ５ａ and R ５ｄ The alkyl group optionally substituted with a fluorine atom or a chlorine atom in the formula (I) 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, 1 to 3, 1 to 2, or 1 carbon atom. Such an alkyl group may be linear or branched.

[0083] In one embodiment, the alkyl group may be substituted with a fluorine atom or a chlorine atom, or is an alkyl group substituted with a fluorine atom.

[0084] In another embodiment, the alkyl group optionally substituted with a fluorine atom or a chlorine atom is an unsubstituted alkyl group.

[0085] R ５ａ and R ５ｄ The alkenyl group optionally substituted with a fluorine atom or a chlorine atom in the formula (I) preferably has 2 to 10 carbon atoms, more preferably 2 to 6 carbon atoms, and even more preferably 2 to 4 carbon atoms, for example, 2 to 3 or 2 carbon atoms. Such an alkenyl group may be linear or branched.

[0086] In one embodiment, the alkenyl group optionally substituted with a fluorine atom or a chlorine atom is an alkenyl group substituted with a fluorine atom or a chlorine atom.

[0087] In another embodiment, the alkenyl group optionally substituted with a fluorine atom or a chlorine atom is an unsubstituted alkenyl group.

[0088] The double bond of the alkenyl group is preferably present at the molecular terminal. ５ｂ It is located at the farthest point from

[0089] In one embodiment, R ５ａ and R ５ｄ are identical.

[0090] In another embodiment, R ５ａ and R ５ｄ is different.

[0091] In one embodiment, R ５ｂ is a single bond.

[0092] In another embodiment, R ５ｂ is —CO—.

[0093] In one embodiment, R ５ｃ is a single bond.

[0094] In another embodiment, R ５ｃ is —CO—.

[0095] In one embodiment, R ５ｂ and R ５ｂ are identical.

[0096] In another embodiment, R ５ｂ and R ５ｂ is different.

[0097] In a preferred embodiment, R ５ａ is an alkyl group optionally substituted with a fluorine atom or a chlorine atom, R ５ｂ is a single bond, R ５ｃ is a single bond, R ５ｄ represents an alkyl or alkenyl group optionally substituted with a fluorine atom.

[0098] The compound containing —O— is preferably represented by the following formula: [In the formula, R ６ are each independently a hydrogen atom or a fluorine atom, ７ are each independently a hydrogen atom, a fluorine atom, or an alkyl group which may be substituted with a fluorine atom, and n is an integer of 1 to 4.

[0099] In one embodiment, R ６ is a hydrogen atom.

[0100] In another embodiment, R ６ is a fluorine atom.

[0101] R ７ The alkyl group optionally substituted with a fluorine atom in the formula (I) 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, 1 to 3 or 1 to 2 carbon atoms. Such an alkyl group may be linear or branched.

[0102] In one embodiment, R ７ One of the groups is a fluorine atom, and the other is an alkyl group which may be substituted with a fluorine atom.

[0103] As the compound containing —O—, for example, the following compounds are used.

[0104] The reaction accelerator may be a compound having a boiling point at 0.1 MPa of, for example, 100°C or lower, preferably 90°C or lower, more preferably 80°C or lower, even more preferably 70°C or lower, even more preferably 65°C or lower, and particularly preferably 50°C or lower. The lower limit of the boiling point is not particularly limited, but may be, for example, -50°C or higher or -30°C or higher. By using a compound with a relatively low temperature of 100°C or lower as the reaction accelerator, it can be easily vaporized in a cylinder, improving the degree of freedom in designing the etching apparatus. Furthermore, since no heating is required or only a small amount of energy is required for heating, energy can be saved.

[0105] The etching gas may further include a phosphorus compound.

[0106] The phosphorus compound is P ４ O １０ (or P ２ O ５ ), P ４ O ８ , and P ４ O ６ oxides such as PF ３ , P.F. ５ , PCl ３ , PCl ５ , PBr ３ , PBr ５ , P.I. ３ halides such as phosphoryl fluoride (POF ３ ), phosphoryl chloride (POCl ３ ), phosphoryl bromide (POBr ３ ), phosphoryl halides such as phosphines (PH ３ ), calcium phosphide (Ca ３ P ２ etc.), phosphoric acid (H ３ P.O. ４ ), sodium phosphate (Na ３ P.O. ４ ), hexafluorophosphate (HPF ６ ), fluorophosphines (H ｘ PF ｙ ) where the sum of x and y is 3 or 5.

[0107] The fluorophosphines include HPF ２ , H ２ PF ３ Examples include:

[0108] In a preferred embodiment, the etching gas is PF ３ , PCl ３ , P.F. ５ , PCl ５ , POCl ３ , P.H. ３ , PBr ３ , or PBr ５ At least one of the following, preferably PF ３ may include:

[0109] The content of the phosphorus compound in the etching gas may be preferably 50% by volume or less, more preferably 40% by volume or less, and even more preferably 30% by volume or less, for example, 20% by volume or less, or 10% by volume or less. The content of the phosphorus compound may be, for example, 1% by volume or more, 5% by volume or more, or 10% by volume or more.

[0110] The etching gas may further contain other compounds containing carbon or hydrogen. Such compounds include H ２ , hydrocarbons (C ｘ H ｙ ), fluorocarbon (C ｘ F ｙ ), hydrofluorocarbons (CH ｘ F ｙ ), or NH ３ wherein x and y are each any integer.

[0111] The etching gas may further include oxygen.

[0112] The etching gas may be diluted with an inert gas as needed.

[0113] Examples of inert gases include rare gases and nitrogen. Examples of rare gases include helium, neon, argon, xenon, and krypton. These inert gases can be used alone or in combination of two or more. These inert gases can be known or commercially available.

[0114] When the etching gas is diluted with an inert gas, the amount of the inert gas can be, for example, 0.1 to 10% by volume, with the total amount of the etching gas being 1 part by volume.

[0115] The flow rate of the etching gas in step (2) may be preferably 5 to 2000 sccm, more preferably 10 to 1000 sccm. When the etching gas is diluted with an inert gas, the flow rate is the flow rate of the mixture of the etching gas and the inert gas.

[0116] The aspect ratio of the processed shape (also referred to as a pattern) formed by the etching method of the present disclosure may be preferably 50 or more, more preferably 60 or more, even more preferably 70 or more, and even more preferably 75 or more. The pattern is preferably a contact hole or a line and space. Here, the aspect ratio is the ratio of the depth to the width (or diameter) of the formed pattern.

[0117] The supply temperature of the etching gas in step (2) may be preferably 50° C. or less, more preferably 30° C. or less.

[0118] The substrate temperature in step (2) may be preferably 50° C. or lower, more preferably 30° C. or lower, and even more preferably 20° C. or lower, for example, 10° C. or lower, 5° C. or lower, 0° C. or lower, −20° C. or lower, or −40° C. or lower. The substrate temperature in step (2) may be, for example, −100° C. or higher, −80° C. or higher, −60° C. or higher, −50° C. or higher, or −40° C. or higher.

[0119] The pressure in the chamber in step (2) is 0.5 Pa to 15 Pa.

[0120] The high frequency RF power in step (2) may be preferably 200 to 20,000 W, more preferably 400 to 10,000 W.

[0121] The low frequency RF power in step (2) may be 10 kW or more, preferably 20 kW or more.

[0122] The electron density in step (2) is preferably 10 ９ ~10 １３ cm －３ , more preferably 10 １０ ~10 １２ cm －３ It could be.

[0123] The present invention will be specifically described below using examples, but the present invention is not limited to these examples.

[0124] In Examples 1 to 10 and Comparative Examples 1 and 2, each gas was introduced into a CCP (Capacitively Coupled Plasma) plasma device at the flow rate (sccm) shown in Table 1. The process pressure was maintained at 30 mTorr using a pressure control valve, and a superimposed power of 60 MHz high-frequency power at 4500 / 200 W and 0.4 MHz high-frequency power at 20,000 / 1000 W was applied in a 2 kHz pulse with a high / low ratio of 38% to generate plasma. Etching was performed for 30 seconds in Comparative Examples 1 and 2, and for 20 seconds in Examples 3 to 10, and the etching rate (ER) was measured. The film to be etched was a laminated film formed by alternately stacking multiple silicon oxide films (50 nm) and silicon nitride films (50 nm) patterned using an amorphous carbon film as an etching mask. The results are shown in Table 1.

[0125] In Table 1, C ４ F ９ OH represents nonafluoro-tert-butyl alcohol, and CH ３ CHO indicates acetaldehyde, C ３ H ４ F ４ O represents methyl 1,1,2,2-tetrafluoroethyl ether, and C ４ H ４ F ６ O represents 1,1,1,3,3,3-hexafluoropropan-2-ol, and ESC represents an electrostatic chuck.

[0126]

[0127] The following films were etched and the etching rates were measured under the conditions of Comparative Examples 1 and 2, and Examples 5, 7 and 10. The films to be etched were a silicon oxide film having a thickness of 1050 nm and a silicon nitride film having a thickness of 500 nm.

[0128]

[0129] Example 11 and Comparative Example 3: Each gas was introduced into a CCP (Capacitively Coupled Plasma) plasma device at the flow rate (sccm) shown in Table 3. The process pressure was maintained at 30 mTorr using a pressure control valve. A superimposed power of 60 MHz high-frequency power (4500 / 200 W) and 0.4 MHz high-frequency power (10,000 / 1,000 W) was applied in a 2 kHz pulse with a high / low ratio of 38% to generate plasma. Etching was performed for 90 seconds, and the etching rate (ER) was measured. The film to be etched was a laminate film formed by alternately stacking multiple silicon oxide films (50 nm) and silicon nitride films (50 nm) patterned using an amorphous carbon film as an etching mask. The results are shown in Table 3. SEM images before etching are shown in Figure 1, and SEM images after etching for Example 11 and Comparative Example 3 are shown in Figures 2 and 3, respectively.

[0130] In Table 3, C ３ HF ６ OH denotes hexafluoro-2-propanol, and ESC denotes electrostatic chuck.

[0131]

[0132] The etching method of the present disclosure is suitable for use in etching a substrate having a silicon-containing film.

Claims

1. A method for etching a silicon-containing film, comprising: (1) providing a substrate having a silicon-containing film in a chamber; and (2) etching the silicon-containing film under plasma conditions using an etching gas containing hydrogen fluoride and a reaction accelerator, wherein the partial pressure of hydrogen fluoride in the etching gas is the highest.

2. The etching method according to claim 1, wherein the reaction accelerator includes a compound having a fluorine atom.

3. The etching method according to claim 1 or 2, wherein the reaction accelerator comprises a compound having a structure selected from —OH, —CHO, —COOH, —C—O—C— and —CO—.

4. The etching method according to claim 3, wherein the compound having —OH has a boiling point of 100° C. or less at 0.1 MPa.

5. The etching method according to claim 3, wherein the compound having —OH has a boiling point of 96° C. or less at 0.1 MPa.

6. The etching method according to claim 3, wherein the compound having —OH has a boiling point of 85° C. or less at 0.1 MPa.

7. The etching method according to claim 3, wherein the compound having —OH has a boiling point of 60° C. or less at 0.1 MPa.

8. The compound containing —OH has the formula: R １ａ -R １ｂ -R １ｃ -OH HO-R １ｂ -OH [wherein, R １ａ is a hydrogen atom, a fluorine atom, or —NH ２ and R １ｂ is an alkylene group optionally substituted by a fluorine atom, R １ｃ is a single bond or -SO ２ 8. The etching method according to claim 3, wherein the compound is a compound represented by the formula:

9. R １ａ is a hydrogen atom or a fluorine atom, R １ｂ is an alkylene group having 1 to 4 carbon atoms which may be substituted with a fluorine atom, R １ｃ The etching method according to claim 8 , wherein is a single bond.

10. R １ａ is a hydrogen atom, and R １ｂ is an alkylene group having 1 to 2 carbon atoms, and R １ｃ The etching method according to claim 8 or 9, wherein is a single bond.

11. R １ａ is a hydrogen atom or a fluorine atom, R １ｂ is a fluorinated alkylene group having 1 to 4 carbon atoms and substituted with a fluorine atom, R １ｃ The etching method according to claim 8 or 9, wherein is a single bond.

12. Compounds containing -CHO have the formula: R ２ａ -R ２ｂ -CHO [wherein, R ２ａ is a hydrogen atom, a fluorine atom or —OH, R ２ｂ The etching method according to claim 3 , wherein the compound is a compound represented by the formula:

13. R ２ａ is a hydrogen atom or a fluorine atom, R ２ｂ The etching method according to claim 12 , wherein represents a single bond or an alkylene group having one carbon atom which may be substituted with a fluorine atom.

14. A compound containing -COOH has the formula: R ３ａ -R ３ｂ -R ３ｃ -COOH [wherein, R ３ａ is a hydrogen atom or a fluorine atom, R ３ｂ is a single bond or an alkylene group optionally substituted with a fluorine atom, R ３ｃ is a single bond or -SO ２ 4. The etching method according to claim 3, wherein the compound is a compound represented by the formula:

15. R ３ａ is a hydrogen atom or a fluorine atom, R ３ｂ is a single bond or an alkylene group having 1 carbon atom which may be substituted with a fluorine atom, R ３ｃ The etching method according to claim 14 , wherein is a single bond.

16. A compound containing -CO- has the following formula: R ４ａ -R ４ｂ -CO-R ４ｃ -R ４ｄ [In the formula, R ４ａ is a hydrogen atom, a fluorine atom, or an alkyl group optionally substituted by a fluorine atom, and R ４ｂ is a single bond or a group containing at least one group selected from an unsaturated alkylene group optionally substituted with an oxygen atom and a fluorine atom, and R ４ｃ is a single bond or -SO ２ - and R ４ｄ The etching method according to claim 3 , wherein the compound is a compound represented by the formula:

17. R ４ａ is a hydrogen atom, a fluorine atom, or an alkyl group optionally substituted by a fluorine atom, and R ４ｂ is a single bond, or —CH═CF—, —O—CH═CH—, and R ４ｃ is a single bond, R ４ｄ The etching method according to claim 16 , wherein is a hydrogen atom, a fluorine atom, or an alkyl group substituted with a fluorine atom.

18. A compound containing —O— is represented by the following formula: R ５ａ -R ５ｂ -O-R ５ｃ -R ５ｄ [In the formula, R ５ａ is an alkyl or alkenyl group optionally substituted with a fluorine atom or a chlorine atom, R ５ｂ is a single bond or —CO—, R ５ｃ is a single bond or —CO—, R ５ｄ and n is an alkyl group or an alkenyl group which may be substituted with a fluorine atom or a chlorine atom.

19. R ５ａ is an alkyl group optionally substituted with a fluorine atom or a chlorine atom, R ５ｂ is a single bond, R ５ｃ is a single bond, R ５ｄ The etching method according to claim 18 , wherein is an alkyl group or an alkenyl group optionally substituted with a fluorine atom.

20. A compound containing -O- has the following formula: [In the formula, R ６ are each independently a hydrogen atom or a fluorine atom, ７ are each independently a hydrogen atom, a fluorine atom, or an alkyl group which may be substituted with a fluorine atom, and n is an integer of 1 to 4.

21. The etching method according to any one of claims 1 to 20, wherein the aspect ratio of the processed shape formed is 50 or more.

22. The etching method according to any one of claims 1 to 21, wherein the temperature of the etching gas supplied in step (2) is in the range of 90°C or less.

23. An etching method according to any one of claims 1 to 22, wherein the reaction accelerator contains a compound having a boiling point of 90°C or less at 0.1 MPa.

24. An etching method according to any one of claims 1 to 23, wherein the reaction accelerator contains a compound having a boiling point of 65°C or less at 0.1 MPa.

25. The etching method according to any one of claims 1 to 24, wherein the substrate temperature in step (2) is 20°C or less.

26. The etching method according to any one of claims 1 to 5, wherein the pressure in the chamber in step (2) is 0.5 Pa to 15 Pa.

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