Etching method
The etching method enhances efficiency by using hydrogen fluoride with reaction accelerators like -OH, -CHO, -COOH, or -CO- compounds, addressing inefficiencies in existing methods and reducing energy requirements.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- DAIKIN INDUSTRIES LTD
- Filing Date
- 2026-04-30
- Publication Date
- 2026-07-02
AI Technical Summary
Existing etching methods are inefficient and require additional heating to volatilize reaction by-products, limiting the flexibility and efficiency of the process.
An etching method using hydrogen fluoride as the primary component with a reaction accelerator containing compounds like -OH, -CHO, -COOH, or -CO-, which promote etching under plasma conditions without the need for additional heating, enhancing etching efficiency and flexibility.
Improves etching rate and efficiency by using compounds with low boiling points to facilitate easier vaporization and reduce energy consumption, while maintaining high etching rates and pattern precision.
Smart Images
Figure 2026110867000010 
Figure 2026110867000011 
Figure 2026110867000012
Abstract
Description
[Technical Field]
[0001] This disclosure relates to an etching method. [Background technology]
[0002] A method is known that enables efficient etching by using etching gases containing phosphorus, fluorine, and hydrogen fluoride (Patent Document 1). [Prior art documents] [Patent Documents]
[0003] [Patent Document 1] Japanese Patent Publication No. 2023-067527 [Overview of the Initiative] [Problems that the invention aims to solve]
[0004] This disclosure aims to provide a more efficient etching method. [Means for solving the problem]
[0005] This disclosure includes the following aspects: [Section 1] A method for etching a silicon-containing film, (1) Provide a substrate having a silicon-containing film inside the chamber. (2) Etching the silicon-containing film under plasma conditions using an etching gas containing hydrogen fluoride and a reaction accelerator. An etching method comprising the etching gas wherein the partial pressure of hydrogen fluoride is the largest. [Section 2] The etching method according to item 1, wherein the reaction accelerator comprises a compound having a fluorine atom. [Section 3] The etching method according to claim 1 or 2, wherein the reaction promoter includes a compound having a structure selected from -OH, -CHO, -COOH, -C-O-C- and -CO-. [Claim 4] The etching method according to claim 3, wherein the compound having -OH has a boiling point of 100 °C or lower at 0.1 MPa. [Claim 5] The etching method according to claim 3, wherein the compound having -OH has a boiling point of 96 °C or lower at 0.1 MPa. [Claim 6] The etching method according to claim 3, wherein the compound having -OH has a boiling point of 85 °C or lower at 0.1 MPa. [Claim 7] The etching method according to claim 3, wherein the compound having -OH has a boiling point of 60 °C or lower at 0.1 MPa. [Claim 8] The compound containing -OH has the following formula: R 1a -R 1b -R 1c -OH HO-R 1b -OH [wherein, R 1a is a hydrogen atom, a fluorine atom or -NH2, R 1b is an alkylene group optionally substituted by a fluorine atom, R 1c is a single bond or -SO2-.] The etching method according to claim 3, which is a compound represented by the above formula. [Claim 9] R 1a is a hydrogen atom or a fluorine atom, R 1b is an alkylene group having 1 to 4 carbon atoms optionally substituted by a fluorine atom, R 1c is a single bond, The etching method according to claim 8. [Claim 10] R 1a is a hydrogen atom, R 1bThis is an alkylene group having 1 to 2 carbon atoms. R 1c It is a single bond. The etching method described in item 8 or 9. [Section 11] R 1a is a hydrogen atom or a fluorine atom, R 1b This is a fluorinated alkylene group having 1 to 4 carbon atoms, which is substituted with a fluorine atom. R 1c It is a single bond. The etching method described in any one of items 8 to 10. [Section 12] - Compounds containing CHO are given by the following formula: R 2a -R 2b -CHO [In the formula, R 2a is a hydrogen atom, a fluorine atom, or -OH, R 2b This is an alkylene group which may be substituted with a single bond or a fluorine atom. The etching method described in item 3, wherein the compound is represented by [the compound]. [Section 13] R 2a is a hydrogen atom or a fluorine atom, R 2b This is a C1 alkylene group which may be substituted with a single bond or a fluorine atom. The etching method described in item 13. [Section 14] Compounds containing -COOH are given by the following formula: R 3a -R 3b -R 3c -COOH [In the formula, R 3a is a hydrogen atom or a fluorine atom, R 3b This is an alkylene group which may be substituted with a single bond or a fluorine atom. R 3c This is a single bond, or -SO2-. The etching method described in item 3, wherein the compound is represented by [the compound]. [Section 15] R 3a is a hydrogen atom or a fluorine atom, R 3b This is a C1 alkylene group which may be substituted with a single bond or a fluorine atom. R 3c It is a single bond. The etching method described in item 14. [Section 16] Compounds containing -CO- are defined by 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 which may be substituted with a fluorine atom, R 4b This group comprises at least one group selected from single bonds or unsaturated alkylene groups which may be substituted with oxygen and fluorine atoms. R 4c It is a single bond, or -SO2-, R 4d This is an alkyl group which may be substituted with a hydrogen atom, a fluorine atom, or a fluorine atom. The etching method described in item 3, wherein the compound is represented by [the compound]. [Section 17] R 4a is a hydrogen atom, a fluorine atom, or an alkyl group which may be substituted with a fluorine atom, R 4b These are single bonds, or -CF=CH-, -O-CH=CH-, R 4c It is a single bond, R 4d This is a hydrogen atom, a fluorine atom, or an alkyl group substituted with a fluorine atom. The etching method described in item 16. [Section 18] Compounds containing -O- are defined by the following formula: R 5a -R 5b -OR 5c -R 5d [In the formula, R 5a This is an alkyl or alkenyl group which may be substituted with a fluorine atom or a chlorine atom. R 5b It is a single bond, or -CO-, R 5c It is a single bond, or -CO-, R 5d This is an alkyl or alkenyl group which may be substituted with a fluorine atom or a chlorine atom. The etching method described in item 3, wherein the compound is represented by [the compound]. [Section 19] R 5a This is an alkyl group which may be substituted with a fluorine atom or a chlorine atom. R 5b It is a single bond, R 5c It is a single bond, R 5d This is an alkyl or alkenyl group which may be substituted with a fluorine atom. The etching method described in item 18. [Section 20] Compounds containing -O- are defined by the following formula: TIFF2026110867000001.tif3157[In the formula, R 6 These are, independently, a hydrogen atom or a fluorine atom. R 7 Each of these is independently a hydrogen atom, a fluorine atom, or an alkyl group which may be substituted with a fluorine atom. n is an integer between 1 and 4. The etching method described in item 3, wherein the compound is represented by [the compound]. [Section 21] The etching method according to any one of items 1 to 20, wherein the aspect ratio of the processed shape formed is 50 or more. [Section 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 in the temperature range of 90°C or less. [Section 23] The etching method according to any one of items 1 to 22, wherein the reaction accelerator comprises a compound having a boiling point of 90°C or less at 0.1 MPa. [Section 24] The etching method according to any one of items 1 to 23, wherein the reaction accelerator comprises a compound having a boiling point of 65°C or less at 0.1 MPa. [Section 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. [Section 26] The etching method according to any one of items 1 to 25, wherein the pressure inside the chamber in step (2) is 0.5 Pa to 15 Pa. [Effects of the Invention]
[0006] According to the method disclosed herein, the etching rate is improved, and etching becomes more efficient. [Brief explanation of the drawing]
[0007] [Figure 1] Figure 1 shows an SEM image of the film before etching in Example 11. [Figure 2] Figure 2 is an SEM image of the film after etching in Example 11. [Figure 3] Figure 3 shows an SEM image of the film after etching in Comparative Example 3. [Modes for carrying out the invention]
[0008] The etching method disclosed herein is a method for etching a silicon-containing film, (1) Provide a substrate having a silicon-containing film inside the chamber. (2) Etching the silicon-containing film under plasma conditions using an etching gas containing hydrogen fluoride and a reaction accelerator. The etching gas contains the following, and in the etching gas, the partial pressure of hydrogen fluoride is the largest.
[0009] Step (1) Provide a substrate having a silicon-containing film into the chamber.
[0010] The substrate has a silicon-containing film. In the etching method of this disclosure, the silicon-containing film is etched.
[0011] The silicon-containing film described above 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 have a mask. The mask is provided on a 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; that is, the mask has a pattern that is transferred to the silicon-containing film during the etching process.
[0016] 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.
[0017] The size and material of the chamber are not particularly limited and can be appropriately selected according to 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 this disclosure contains hydrogen fluoride, with hydrogen fluoride having the highest partial pressure.
[0020] The concentration of hydrogen fluoride in the etching gas is preferably 10% by volume or more, more preferably 20% by volume or more, 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. Alternatively, the concentration of hydrogen fluoride may be 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 above-mentioned reaction accelerator is a compound that promotes etching. The etching gas of this disclosure has an improved etching rate due to the inclusion of the reaction accelerator.
[0022] The reaction accelerator described above is preferably a compound containing a fluorine atom. By using a compound containing a fluorine atom, the fluorine dissociated in the plasma promotes etching, which can improve the etching rate.
[0023] The fluorine atom content in a compound containing fluorine atoms is preferably 15 atomic% or more, more preferably 30 atomic% or more, even more preferably 40 atomic% or more, and even 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 above reaction accelerator preferably comprises a compound having a structure selected from -OH, -CHO, -COOH, -COC-, and -CO-. Having such a structure in the reaction accelerator generates H2O in the plasma, thereby accelerating etching. While the present invention is not limited to theory, for example, if the silicon-containing film is a silicon oxide film or a silicon nitride film, the following mechanism is conceivable. Oxide film: SiO2 + 4HF + H2O → SiF4↑ + 3H2O Nitride film: Si3N4 + 16HF → 2(NH4)2SiF6 + SiF4(1) (NH4)2SiF6→2NH3↑+SiF4↑+2HF+H2O (2) This disclosure is not bound by theory, but it is generally believed that the (NH4)2SiF6 produced in reaction (1) inhibits etching. Heating is required to volatilize the (NH4)2SiF6 produced in (1), but in the present invention, as in (2), water generated in the plasma acts as a catalyst and promotes the decomposition reaction of (NH4)2SiF6, thereby improving the etching rate.
[0025] The above-mentioned compound containing -OH may be a compound having a boiling point at 0.1 MPa preferably 100°C or lower, more preferably 96°C or lower, even more preferably 85°C or lower, even more preferably 60°C or lower, and particularly preferably 50°C or lower. The lower limit of the above boiling point is not particularly limited, but may be, for example, -50°C or higher or -30°C or higher.
[0026] The compound containing the above-mentioned -OH is preferably of the following formula: R 1a -R 1b -R 1c -OH HO-R 1b -OH [In the formula, R 1a is a hydrogen atom, a fluorine atom, or -NH2, R 1b This is an alkylene group which may be substituted with a fluorine atom, R 1cThis is a single bond, or -SO2-. It is a compound represented by [formula].
[0027] In one embodiment, a compound containing -OH is R 1a -R 1b -R 1c -OH
[0028] In another embodiment, a compound containing -OH is HO-R 1b -OH
[0029] In one embodiment, R 1a This is either a hydrogen atom or a fluorine atom.
[0030] In one embodiment, R 1a This is a hydrogen atom.
[0031] In another embodiment, R 1a This is a fluorine atom.
[0032] In another embodiment, R 1a It is -NH2.
[0033] R 1b The alkylene group, which may be 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 alkylene group may be linear or branched.
[0034] In one embodiment, R 1b This is an alkylene group substituted with a fluorine atom.
[0035] In another embodiment, R 1b This is an unsubstituted alkylene group.
[0036] In one embodiment, R 1c It is a single bond.
[0037] In another embodiment, R1c It is -SO2-.
[0038] In a preferred embodiment, R 1a is a hydrogen atom or a fluorine atom, R 1b This is an alkylene group having 1 to 4 carbon atoms, which may be substituted with a fluorine atom. R 1c It is a single bond.
[0039] In a preferred embodiment, R 1a It is a hydrogen atom, R 1b This is an alkylene group having 1 to 2 carbon atoms. R 1c It is a single bond.
[0040] In a preferred embodiment, R 1a is a hydrogen atom or a fluorine atom, R 1b This is a fluorinated alkylene group having 1 to 4 carbon atoms, which is substituted with a fluorine atom. R 1c It is a single bond.
[0041] Examples of the compound 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, and 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 preferable, and perfluoro-tert-butyl alcohol, 1,1,1,3,3,3-hexafluoroisopropyl alcohol, 2,2,2-trifluoroethanol, or ethanol is more preferable.
[0042] The compound containing -CHO is preferably represented by the following formula: R 2a -R 2b -CHO [wherein, R 2a is a hydrogen atom, a fluorine atom or -OH, and R 2b is a single bond or an alkylene group optionally substituted by a fluorine atom.] It is a compound represented by the formula.
[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 by a fluorine atom of R is preferably a C1-C10 alkylene group, more preferably a C1-C6 alkylene group, still more preferably a C1-C4 alkylene group, and can be, for example, C1-C3, C1-C2 or 1. Such an alkylene group may be linear or branched.
[0048] In one embodiment, R 2b is an alkylene group substituted by 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 is a single bond or a C1 alkylene group optionally substituted by a fluorine atom,
[0051] Examples of the compound containing -CHO include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, 2,2,2-trifluoroacetaldehyde, F-CHO, CF3CF2-CHO, CF3CF2CF2CF2-CHO.
[0052] The above compound containing -COOH is preferably the following formula: R 3a -R 3b -R 3c -COOH [In the formula, R 3a is a hydrogen atom or a fluorine atom, R 3b This is an alkylene group which may be substituted with a single bond or a fluorine atom. R 3c This is a single bond, or -SO2-. It is a compound represented by [formula].
[0053] In one embodiment, R 3a This is a hydrogen atom.
[0054] In another embodiment, R 3a This is a fluorine atom.
[0055] R 3b The alkylene group, which may be 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 alkylene group may be linear or branched.
[0056] In one embodiment, R 3b This is an alkylene group substituted with a fluorine atom.
[0057] In another embodiment, R 3b This is an unsubstituted alkylene group.
[0058] In one embodiment, R 3c It is a single bond.
[0059] In another embodiment, R 3c It is -SO2-.
[0060] In a preferred embodiment, R 3a is a hydrogen atom or a fluorine atom, R3b This is a C1 alkylene group which may be substituted with a single bond or a fluorine atom. R 3c It is a single bond.
[0061] Examples of compounds containing -COOH include formic acid, acetic acid, butyric acid, or valeric acid.
[0062] The above compound containing -CO- is preferably of 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 which may be substituted with a fluorine atom, R 4b This group comprises at least one group selected from single bonds or unsaturated alkylene groups which may be substituted with oxygen and fluorine atoms. R 4c It is a single bond, or -SO2-, R 4d This is an alkyl group which may be substituted with a hydrogen atom, a fluorine atom, or a fluorine atom. It is a compound represented by [formula].
[0063] R 4a and R 4d The alkyl group in which the fluorine atom may be substituted is preferably having 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 alkyl groups may be linear or branched.
[0064] In one embodiment, R 4a This is a hydrogen atom.
[0065] In another embodiment, R 4a This is a fluorine atom.
[0066] In another embodiment, R 4a This is an alkyl group substituted with a fluorine atom.
[0067] In another embodiment, R 4a This is an unsubstituted alkyl group.
[0068] In one embodiment, R 4d This is a hydrogen atom.
[0069] In another embodiment, R 4d This is a fluorine atom.
[0070] In another embodiment, R 4d This is an alkyl group substituted with a fluorine atom.
[0071] In another embodiment, R 4d This is an unsubstituted alkyl group.
[0072] R 4b The alkylene group, which may be 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 alkylene group may be linear or branched.
[0073] In one embodiment, the alkylene group which may be substituted with the fluorine atom is an alkylene group which is substituted with a fluorine atom.
[0074] In another embodiment, the alkylene group which may be substituted with the fluorine atom is an unsubstituted alkylene group.
[0075] In one embodiment, R 4b It is a single bond.
[0076] In one embodiment, R 4b This is -CH=CF- or -O-CH=CH-. Here, the left side is R 4a Combine.
[0077] In one embodiment, R 4c It is a single bond.
[0078] In another embodiment, R 4c It is -SO2-.
[0079] In a preferred embodiment, R 4a is an alkyl group which may be substituted with a fluorine atom, R 4b This is a single bond, or -O-CH=CH-, R 4c It is a single bond, R 4d This is an alkyl group substituted with a fluorine atom.
[0080] Examples of compounds containing -CO- include the following: O=CF2 CF3CF2-C(=O)-F CF3-C(=O)-CF3 CH2=CF-C(=O)-F TIFF2026110867000002.tif2156 TIFF2026110867000003.tif2245
[0081] The compound containing the above-mentioned -O- is preferably of the following formula: R 5a -R 5b -OR 5c -R 5d [In the formula, R 5a This is an alkyl or alkenyl group which may be substituted with a fluorine atom or a chlorine atom. R 5b It is a single bond, or -CO-, R 5c It is a single bond, or -CO-, R 5dThis is an alkyl or alkenyl group which may be substituted with a fluorine atom or a chlorine atom. This is a compound represented by the formula shown. Here, -O- is preferably an etheric oxygen atom.
[0082] R 5a and R 5d The alkyl group in which the alkyl group may be substituted with a fluorine or chlorine 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 alkyl groups 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 which may be substituted with a fluorine atom or a chlorine atom is an unsubstituted alkyl group.
[0085] R 5a and R 5d The alkenyl group in which the fluorine or chlorine atom may be substituted is preferably having 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 alkenyl group may be linear or branched.
[0086] In one embodiment, the alkenyl group which may be substituted with a fluorine atom or a chlorine atom is an alkenyl group which is substituted with a fluorine atom or a chlorine atom.
[0087] In another embodiment, the alkenyl group which may be substituted with a fluorine atom or a chlorine atom is an unsubstituted alkenyl group.
[0088] The double bond of the alkenyl group is preferably located at the molecular terminal. That is, the double bond of the alkenyl group is R5b It is located at the point furthest from the source.
[0089] In one embodiment, R 5a and R 5d They are identical.
[0090] In another embodiment, R 5a and R 5d They are different.
[0091] In one embodiment, R 5b It is a single bond.
[0092] In another embodiment, R 5b It is -CO-.
[0093] In one embodiment, R 5c It is a single bond.
[0094] In another embodiment, R 5c It is -CO-.
[0095] In one embodiment, R 5b and R 5b They are identical.
[0096] In another embodiment, R 5b and R 5b They are different.
[0097] In a preferred embodiment, R 5a This is an alkyl group which may be substituted with a fluorine atom or a chlorine atom. R 5b It is a single bond, R 5c It is a single bond, R 5d This is an alkyl or alkenyl group which may be substituted with a fluorine atom.
[0098] The compound containing the above-mentioned -O- is preferably of the following formula: TIFF2026110867000004.tif3157[In the formula, R 6 These are, independently, a hydrogen atom or a fluorine atom. R 7 Each of these is independently a hydrogen atom, a fluorine atom, or an alkyl group which may be substituted with a fluorine atom. n is an integer between 1 and 4. The compound is represented by
[0099] In one embodiment, R 6 This is a hydrogen atom.
[0100] In another embodiment, R 6 This is a fluorine atom.
[0101] R 7 The alkyl group in which the fluorine atom may be substituted is preferably having 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 alkyl groups may be linear or branched.
[0102] In one embodiment, R 7 One of them is a fluorine atom, and the other is an alkyl group which may be substituted with a fluorine atom.
[0103] Examples of compounds containing -O- include the following: TIFF2026110867000005.tif130146
[0104] The reaction accelerator described above 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 boiling point of 100°C or lower as a reaction accelerator, it can be easily vaporized in a cylinder, improving the design flexibility of the etching apparatus. In addition, energy can be saved because heating is not required or the energy required for heating is small.
[0105] The etching gas may further contain phosphorus compounds.
[0106] The above phosphorus compound is P4O 10 Oxides such as (or P2O5), P4O8, and P4O6, halides such as PF3, PF5, PCl3, PCl5, PBr3, PBr5, PI3, phosphoryl fluoride (POF3), phosphoryl chloride (POCl3), phosphoryl bromide (POBr3), and other phosphoryl halides, phosphine (PH3), calcium phosphide (Ca3P2, etc.), phosphoric acid (H3PO4), sodium phosphate (Na3PO4), hexafluorophosphate (HPF6), fluorophosphines (H x PF y ) may also be the case. Here, the sum of x and y is 3 or 5.
[0107] Examples of the above-mentioned fluorophosphines include HPF2 and H2PF3.
[0108] In a preferred embodiment, the etching gas may include at least one of PF3, PCl3, PF5, PCl5, POCl3, PH3, PBr3, or PBr5, preferably PF3.
[0109] The phosphorus compound content in the etching gas may be preferably 50% by volume or less, more preferably 40% by volume or less, even more preferably 30% by volume or less, for example, 20% by volume or less, or 10% by volume or less. The phosphorus compound content 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 having carbon or hydrogen. Such compounds include H2, hydrocarbons (C x H y ), fluorocarbon (C x F y ), hydrofluorocarbon (CH x F y ), or may contain at least one of NH3 (wherein x and y are any integers).
[0111] Etching gases may also contain oxygen.
[0112] Furthermore, the etching gas may be diluted with an inert gas as needed.
[0113] 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.
[0114] When diluting etching gas with an inert gas, the amount of inert gas can be, for example, 0.1 to 10 volume percent, with the total amount of etching gas being 1 volume part.
[0115] 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.
[0116] The aspect ratio of the processed shape (also called a pattern) formed by the etching method of this disclosure is 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) is preferably 50°C or lower, more preferably 30°C or lower.
[0118] The substrate temperature in step (2) is preferably 50°C or lower, more preferably 30°C or lower, 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) is, 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 inside the chamber during process (2) is between 0.5 Pa and 15 Pa.
[0120] The high frequency RF power in step (2) is 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 10 10 ~10 12 cm -3 It is possible. [Examples]
[0123] The present invention will be described in detail below using examples, but the present invention is not limited to these examples.
[0124] Examples 1-10 and Comparative Examples 1-2 Each gas was introduced into a CCP (Capacitively Coupled Plasma) plasma apparatus at the flow rates (sccm) shown in Table 1. The process pressure was maintained at 30 mTorr using a pressure regulating valve. Plasma was generated by applying a superimposed power of 60 MHz high-frequency power at 4500 / 200 W and 0.4 MHz high-frequency power at 20000 / 1000 W in a pulsed manner at 2 kHz with a high / low ratio of 38%. Etching was performed for 30 seconds for Comparative Examples 1 and 2, and for 20 seconds for Examples 3 to 10, and the etching rate (ER) was measured. The film to be etched was a laminated film in which patterned silicon oxide film (50 nm) and silicon nitride film (50 nm) were alternately stacked multiple times using an amorphous carbon film as an etching mask. The results are shown in Table 1.
[0125] In Table 1, C4F9OH represents nonafluoro-tert-butyl alcohol, CH3CHO represents acetaldehyde, C3H4F4O represents methyl 1,1,2,2-tetrafluoroethyl ether, C4H4F6O represents 1,1,1,3,3,3-hexafluoropropan-2-ol, and ESC represents electrostatic chuck.
[0126] [Table 1]
[0127] The following films were etched under the conditions of Comparative Examples 1 and 2, and Examples 5, 7, and 10, and the etching rate was measured. The films to be etched were a silicon oxide film with a thickness of 1050 nm and a silicon nitride film with a thickness of 500 nm.
[0128] [Table 2]
[0129] Example 11 and Comparative Example 3 Each gas was introduced into a CCP (Capacitively Coupled Plasma) plasma apparatus at the flow rates (sccm) shown in Table 3. The process pressure was maintained at 30 mTorr using a pressure regulating valve. Plasma was generated by applying a superimposed power of 60 MHz high-frequency power at 4500 / 200 W and 0.4 MHz high-frequency power at 10000 / 1000 W in a pulsed manner at 2 kHz with a high / low ratio of 38%. Etching was performed for 90 seconds, and the etching rate (ER) was measured. The film to be etched was a multilayer film in which patterned silicon oxide film (50 nm) and silicon nitride film (50 nm) were alternately stacked multiple times using an amorphous carbon film as an etching mask. The results are shown in Table 3. In addition, the SEM image before etching is shown in Figure 1, and the SEM images after etching for Example 11 and Comparative Example 3 are shown in Figures 2 and 3, respectively.
[0130] In Table 3, C3HF6OH represents hexafluoro-2-propanol, and ESC represents electrostatic chuck.
[0131] [Table 3] [Industrial applicability]
[0132] The etching method of this disclosure is suitably used for etching a substrate having a silicon-containing film.
Claims
1. A method for etching a silicon-containing film, (1) Provide a substrate having a silicon-containing film inside the chamber. (2) Etching the silicon-containing film under plasma conditions using an etching gas containing hydrogen fluoride and a reaction accelerator. An etching method comprising the etching gas wherein the partial pressure of hydrogen fluoride is the largest.
2. The etching method according to claim 1, wherein the reaction accelerator comprises a compound having a fluorine atom.
3. The etching method according to claim 1, 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. Compounds containing -OH are given by the following formula: R １ａ -R １ｂ -R １ｃ -OH HO-R １ｂ -OH [In the formula, R １ａ is a hydrogen atom, a fluorine atom, or -NH ２ And, R １ｂ This is an alkylene group which may be substituted with a fluorine atom, R １ｃ is a single bond or -SO ２ -. ] The etching method according to claim 3, wherein the compound is represented by [formula].
9. R １ａ is a hydrogen atom or a fluorine atom, R １ｂ This is an alkylene group having 1 to 4 carbon atoms, which may be substituted with a fluorine atom. R １ｃ It is a single bond. The etching method according to claim 8.
10. R １ａ It is a hydrogen atom, R １ｂ This is an alkylene group having 1 to 2 carbon atoms. R １ｃ It is a single bond. The etching method according to claim 8.
11. R １ａ is a hydrogen atom or a fluorine atom, R １ｂ This is a fluorinated alkylene group having 1 to 4 carbon atoms, which is substituted with a fluorine atom. R １ｃ It is a single bond. The etching method according to claim 8.
12. Compounds containing -CHO are given by the following formula: R ２ａ -R ２ｂ -CHO [In the formula, R ２ａ is a hydrogen atom, a fluorine atom, or -OH, R ２ｂ This is an alkylene group which may be substituted with a single bond or a fluorine atom. The etching method according to claim 3, wherein the compound is represented by [formula].
13. R ２ａ is a hydrogen atom or a fluorine atom, R ２ｂ This is a C1 alkylene group which may be substituted with a single bond or a fluorine atom. The etching method according to claim 12.
14. Compounds containing -COOH are given by the following formula: R ３ａ -R ３ｂ -R ３ｃ -COOH [In the formula, R ３ａ is a hydrogen atom or a fluorine atom, R ３ｂ This is an alkylene group which may be substituted with a single bond or a fluorine atom. R ３ｃ This is a single bond, or -SO ２ - That is the case. The etching method according to claim 3, wherein the compound is represented by [formula].
15. R ３ａ is a hydrogen atom or a fluorine atom, R ３ｂ This is a C1 alkylene group which may be substituted with a single bond or a fluorine atom. R ３ｃ It is a single bond. The etching method according to claim 14.
16. Compounds containing -CO- are defined by the following formula: R ４ａ -R ４ｂ -C-R ４ｃ -R ４ｄ [In the formula, R ４ａ is a hydrogen atom, a fluorine atom, or an alkyl group which may be substituted with a fluorine atom, R ４ｂ This group comprises at least one group selected from single bonds or unsaturated alkylene groups which may be substituted with oxygen and fluorine atoms. R ４ｃ This is a single bond, or -SO ２ - and R ４ｄ This is an alkyl group which may be substituted with a hydrogen atom, a fluorine atom, or a fluorine atom. The etching method according to claim 3, wherein the compound is represented by [formula].
17. R ４ａ is a hydrogen atom, a fluorine atom, or an alkyl group which may be substituted with a fluorine atom, R ４ｂ These are single bonds, or -CH=CF-, -O-CH=CH-, R ４ｃ It is a single bond, R ４ｄ This is a hydrogen atom, a fluorine atom, or an alkyl group substituted with a fluorine atom. The etching method according to claim 16.
18. Compounds containing -O- are defined by the following formula: R ５ａ -R ５ｂ -O-R ５ｃ -R ５ｄ [In the formula, R ５ａ This is an alkyl or alkenyl group which may be substituted with a fluorine atom or a chlorine atom. R ５ｂ It is a single bond, or -CO-, R ５ｃ It is a single bond, or -CO-, R ５ｄ This is an alkyl or alkenyl group which may be substituted with a fluorine atom or a chlorine atom. The etching method according to claim 3, wherein the compound is represented by [formula].
19. R ５ａ This is an alkyl group which may be substituted with a fluorine atom or a chlorine atom. R ５ｂ It is a single bond, R ５ｃ It is a single bond, R ５ｄ This is an alkyl or alkenyl group which may be substituted with a fluorine atom. The etching method according to claim 18.
20. Compounds containing -O- are defined by the following formula: [In the formula, R ６ These are, independently, a hydrogen atom or a fluorine atom. R ７ Each of these is independently a hydrogen atom, a fluorine atom, or an alkyl group which may be substituted with a fluorine atom. n is an integer between 1 and 4. The etching method according to claim 3, wherein the compound is represented by [formula].
21. The etching method according to claim 1, wherein the aspect ratio of the processed shape formed is 50 or more.
22. The etching method according to claim 1, wherein the supply temperature of the etching gas in step (2) is in the temperature range of 90°C or less.
23. The etching method according to claim 1, wherein the reaction accelerator comprises a compound having a boiling point of 90°C or less at 0.1 MPa.
24. The etching method according to claim 1, wherein the reaction accelerator comprises a compound having a boiling point of 65°C or less at 0.1 MPa.
25. The etching method according to claim 1, wherein the substrate temperature in step (2) is 20°C or less.
26. The etching method according to claim 1, wherein the pressure inside the chamber in step (2) is 0.5 Pa to 15 Pa.