Etching method, method for manufacturing semiconductor device, etching apparatus, and etching gas

Abstract

The purpose of the present invention is to provide a technique capable of etching at least a film containing Si and N while suppressing etching of the film containing at least Si and O in a substrate having a film containing at least Si and O and a film containing at least Si and N. The present invention is an etching method for etching a film containing Si and N by bringing a substrate having a film containing at least Si and O and a film containing at least Si and N into contact with (I) HF gas and (II) at least one compound selected from the group consisting of sulfonyl compounds, carbonyl compounds, sulfonyl isocyanate compounds, and isocyanate compounds.

Description

Technical Field

[0001] The present invention relates to an etching method, a method for manufacturing a semiconductor device, an etching apparatus and an etching gas using HF gas and at least one compound selected from the group consisting of a sulfonyl compound, a carbonyl compound, a sulfonyl isocyanate compound and an isocyanate compound. Background Art

[0002] In the manufacture of semiconductor devices, a process is sometimes performed in which silicon nitride (SiN) is selectively etched through a structure in which silicon oxide (SiO 2 ) is adjacent to silicon nitride (SiN) on a single crystal silicon substrate.

[0003] As a method for etching SiN, wet etching using hot phosphoric acid and dry etching using plasma generated from a compound gas such as halogenated hydrocarbon such as CF 4 are known.

[0004] For example, Patent Document 1 describes that in order to selectively perform plasma etching on SiN in the presence of SiO2, metal silicide, or silicon, a carbonaceous material including the formula: CH x F 4-x A dry etching method using a compound gas represented by (x represents 2 or 3) and an etching gas such as oxygen. Patent document 1 describes that a SiN film is selectively etched from an opening of a SiO2 film and a p-Si film thereunder is used as an etching stopper.

[0005] However, in wet etching using hot phosphoric acid or dry etching using plasma, SiO 2 is also etched in addition to SiN, so there is a concern that it is difficult to increase the selectivity of SiN to SiO 2 .

[0006] Therefore, Patent Document 2 describes a method for etching a SiN film formed on a SiO2 film by flowing HF gas in a plasma-free heated atmosphere. However, in the method described in Patent Document 2, if HF gas is used to etch the SiN film, the SiO2 film may also be etched due to HF and NH3 as a reaction product, and there is also a case where the SiN / SiO2 selectivity ratio cannot be improved.

[0007] Therefore, Patent Document 3 describes a method for etching a SiN film with a high selectivity ratio with respect to a SiO2 film using a mixed gas of HF and a fluorinated carboxylic acid. It is described that the fluorinated carboxylic acid has the following characteristics: it captures NH3 produced as a by-product of etching the SiN film by HF, thereby not etching the SiO2 film, and does not hinder the etching of SiN by HF.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Laid-Open No. 8-59215

[0011] Patent Document 2: Japanese Patent Application Publication No. 2008-187105

[0012] Patent Document 3: Japanese Patent Application Publication No. 2019-91890 Summary of the invention

[0013] Problem that the invention aims to solve

[0014] An object of the present invention is to provide a technology for etching the film containing at least Si and N while suppressing the etching of the film containing at least Si and O in a substrate having a film containing at least Si and O and a film containing at least Si and N.

[0015] Solutions for solving problems

[0016] The present inventors conducted intensive research and found that sulfonyl compounds, carbonyl compounds, sulfonyl isocyanate compounds, or isocyanate compounds can combine with Si-NH2 on the surface of the SiN film to prevent the generation of NH3, which is a by-product of the reaction between HF and SiN, and can etch the SiN film in combination with HF, thereby solving the above-mentioned problems and completing the present invention.

[0017] In the method described in Patent Document 3, fluorinated carboxylic acid and by-produced NH3 form a salt to capture NH3, thereby inhibiting the etching of SiO2 film. On the other hand, the sulfonyl compound, carbonyl compound, sulfonyl isocyanate compound, and isocyanate compound in the present invention do not release protons (H + ), and directly combines with Si-NH2 on the surface of the SiN film, thereby suppressing the generation of NH3 itself. Therefore, it is speculated that the etching inhibition effect of the SiO2 film is further improved.

[0018] That is, the present invention provides an etching method, a method for manufacturing a semiconductor device, and an etching apparatus as described in the following [1] to

[18] .

[0019] [1] An etching method, wherein a substrate having a film containing at least Si and O and a film containing at least Si and N is brought into contact with (I) HF gas and (II) at least one compound selected from the group consisting of a sulfonyl compound represented by the following general formula [1], a carbonyl compound represented by the following general formula [2], a sulfonyl isocyanate compound represented by the following general formula [3], and an isocyanate compound represented by the following general formula [4], thereby etching the above-mentioned film containing Si and N.

[0020] R 1 -S(=O)2-X[1]

[0021] (In the general formula [1], R 1 A linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, or a halogen atom. X is a halogen atom.

[0022] R 2 -C(=O)-R 3 [2]

[0023] (In general formula [2], R 2 and R 3 Each independently represents a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, a hydrogen atom, a halogen atom, or an isocyanate group.

[0024] R 4 -S(=O)2N=C=O[3]

[0025] (In general formula [3], R 4 A linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, or a halogen atom.

[0026] R 5 -N=C=O[4]

[0027] (In general formula [4], R 5 A linear or branched alkyl group having 1 to 10 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms.

[0028] [2] The etching method according to [1] above, wherein the film containing Si and N is etched without being in a plasma state.

[0029] [3] The etching method according to [1] or [2] above, characterized in that the film containing Si and N is selectively etched.

[0030] [4] The etching method according to [1] or [2] above, wherein the etching is performed selectively on the film containing Si and N, and the etching of the film containing Si and O is performed at a rate of 1.0 nm / min or less.

[0031] [5] The etching method according to any one of [1] to [4], wherein R 1 is a fluoroalkyl group or a fluorine atom, and X is a fluorine atom.

[0032] [6] An etching method according to any one of [1] to [5] above, wherein the sulfonyl compound represented by the general formula [1] is trifluoromethanesulfonyl fluoride (CF3S(=O)2F) or sulfonyl fluoride (SO2F2).

[0033] [7] An etching method according to any one of [1] to [6] above, wherein the carbonyl compound represented by the general formula [2] is hexafluoroacetone (CF3C(=O)CF3), trifluoroacetaldehyde (CF3C(=O)H), or fluorocarbonyl isocyanate (FC(=O)N=C=O).

[0034] [8] The etching method according to any one of [1] to [7] above, wherein the isocyanate compound represented by the general formula [3] is fluorosulfonyl isocyanate (FS(=O)2N=C=O).

[0035] [9] The etching method according to any one of [1] to [8], comprising the steps of placing the substrate in a chamber to perform the etching, and applying a reduced pressure to the chamber.

[0036]

[10] The etching method according to any one of [1] to [9] above, wherein the (I) HF gas and the (II) compound are brought into contact with the substrate simultaneously.

[0037]

[11] An etching method according to any one of [1] to [9], comprising: a first etching step of bringing the (I) HF gas into contact with the substrate, and a second etching step of bringing the (II) compound into contact with the substrate.

[0038]

[12] The etching method according to

[11] above, wherein etching is performed by repeating the first etching step and the second etching step.

[0039]

[13] The etching method according to

[11] or

[12] above, wherein the first etching step is performed after the second etching step.

[0040]

[14] An etching method according to any one of [1] to

[13] above, wherein the film containing Si and O is a silicon oxide (SiO 2 ) film.

[0041]

[15] The etching method according to any one of [1] to

[14] above, wherein the film containing Si and N is a silicon nitride (SiN) film.

[0042]

[16] An etching method according to any one of [1] to

[13] above, wherein, in the substrate, the film containing Si and O is a silicon oxide (SiO2) film, the film containing Si and N is a silicon nitride (SiN) film, the silicon nitride film is adjacent to the silicon oxide film, and the silicon oxide film and the silicon nitride film are exposed.

[0043]

[17] A method for manufacturing a semiconductor device, comprising: applying the etching method described in any one of [1] to

[16] above to a substrate having a silicon nitride film and a silicon oxide film, thereby selectively etching the silicon nitride film.

[0044]

[18] An etching device comprising: a mounting table on which a substrate is mounted; an HF gas supply unit which supplies the above-mentioned (I) HF gas; and a gas compound (II) supply unit which supplies (II) a gas of at least one compound selected from the group consisting of a sulfonyl compound represented by the following general formula [1], a carbonyl compound represented by the following general formula [2], a sulfonyl isocyanate compound represented by the following general formula [3], and an isocyanate compound represented by the following general formula [4].

[0045] R 1 -S(=O)2-X[1]

[0046] (In the general formula [1], R 1 A linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, or a halogen atom. X is a halogen atom.

[0047] R 2 -C(=O)-R 3 [2]

[0048] (In general formula [2], R 2 and R 3 Each independently represents a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, a hydrogen atom, a halogen atom, or an isocyanate group.

[0049] R 4 -S(=O)2N=C=O[3]

[0050] (In general formula [3], R 4 A linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, or a halogen atom.

[0051] R 5 -N=C=O[4]

[0052] (In general formula [4], R 5 A linear or branched alkyl group having 1 to 10 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms.

[0053]

[19] An etching gas comprising: (I) HF gas; and (II) at least one compound selected from the group consisting of a sulfonyl compound represented by the following general formula [1], a carbonyl compound represented by the following general formula [2], a sulfonyl isocyanate compound represented by the following general formula [3], and an isocyanate compound represented by the following general formula [4].

[0054] R 1 -S(=O)2-X[1]

[0055] (In the general formula [1], R 1 A linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, or a halogen atom. X is a halogen atom.

[0056] R 2 -C(=O)-R 3 [2]

[0057] (In general formula [2], R 2 and R 3 Each independently represents a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, a hydrogen atom, a halogen atom, or an isocyanate group.

[0058] R 4 -S(=O)2N=C=O[3]

[0059] (In general formula [3], R 4 A linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, or a halogen atom.

[0060] R 5 -N=C=O[4]

[0061] (In general formula [4], R 5 A linear or branched alkyl group having 1 to 10 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms.

[0062] Effects of the Invention

[0063] According to the present invention, by using an etching gas containing HF gas and at least one compound selected from the group consisting of a sulfonyl compound represented by general formula [1], a carbonyl compound represented by general formula [2], a sulfonyl isocyanate compound represented by general formula [3], and an isocyanate compound represented by general formula [4] in a substrate having a film containing at least Si and O and a film containing at least Si and N, the etching of the film containing at least Si and O can be suppressed and the film containing at least Si and N can be etched. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 This is a schematic diagram schematically showing an etching device according to one embodiment of the present invention. DETAILED DESCRIPTION

[0065] The present invention will be described in detail below. The present invention is not limited to the following embodiments, and can be appropriately implemented based on common knowledge of those skilled in the art within the scope not hindering the gist of the present invention.

[0066] <Etching method>

[0067] The etching method of the present invention is characterized in that a substrate having a film containing at least Si and O and a film containing at least Si and N is brought into contact with (I) HF gas and (II) at least one compound selected from the group consisting of a sulfonyl compound represented by the following general formula [1], a carbonyl compound represented by the following general formula [2], a sulfonyl isocyanate compound represented by the following general formula [3], and an isocyanate compound represented by the following general formula [4] (hereinafter also referred to as "compound (II)"), thereby etching the above-mentioned film containing Si and N.

[0068] R 1 -S(=O)2-X[1]

[0069] (In the general formula [1], R 1 It is a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, or a halogen atom. X is a halogen atom)

[0070] R 2 -C(=O)-R 3 [2]

[0071] (In general formula [2], R 2 and R 3 Each independently represents a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, a hydrogen atom, a halogen atom, or an isocyanate group)

[0072] R 4 -S(=O)2N=C=O[3]

[0073] (In general formula [3], R 4 A linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, or a halogen atom)

[0074] R 5 -N=C=O[4]

[0075] (In general formula [4], R 5A linear or branched alkyl group having 1 to 10 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms)

[0076] As a film containing at least Si and O, a silicon oxide (SiO 2 ) film can be cited.

[0077] An example of a film containing at least Si and N is a silicon nitride (SiN) film.

[0078] As R of the general formula [1] 1 The R of the general formula [1] may be a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, and n-hexyl. 1 The halogen atom includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

[0079] R 1 A fluoroalkyl group or a fluorine atom is preferred. 1 A trifluoromethyl group or a fluorine atom is more preferred.

[0080] Examples of the halogen atom X in the general formula [1] include 1 X is preferably a fluorine atom.

[0081] Specific examples of the sulfonyl compound represented by the general formula [1] include trifluoromethanesulfonyl fluoride (CF3S(=O)2F), sulfonyl fluoride (SO2F2), trifluoromethanesulfonyl chloride (CF3S(=O)2Cl), sulfonyl chloride (SO2Cl2), etc. The sulfonyl compound is preferably trifluoromethanesulfonyl fluoride (CF3S(=O)2F) or sulfonyl fluoride (SO2F2).

[0082] As R of the general formula [2] 2 and R 3 A linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, and a halogen atom, and examples thereof include R of the general formula [1] 1 As those exemplified. 2 and R 3 , preferably an alkyl group, a trifluoroalkyl group or a hydrogen atom, more preferably a methyl group, a trifluoromethyl group or a hydrogen atom. Also preferably R 2 and R 3 A carbonyl compound in which either one of them is a halogen atom and the other is an isocyanate group.

[0083] Specific examples of the carbonyl compound represented by the general formula [2] include hexafluoroacetone (CF3C(=O)CF3), trifluoroacetaldehyde (CF3C(=O)H), acetone (CH3C(=O)CH3), acetaldehyde (CH3C(=O)H), fluorocarbonyl isocyanate (FC(=O)N=C=O), chlorocarbonyl isocyanate (ClC(=O)N=C=O), etc.

[0084] The above-mentioned carbonyl compound is preferably hexafluoroacetone (CF3C(=O)CF3), trifluoroacetaldehyde (CF3C(=O)H), fluorocarbonyl isocyanate (FC(=O)N=C=O), and hexafluoroacetone (CF3C(=O)CF3) and trifluoroacetaldehyde (CF3C(=O)H).

[0085] Acetaldehyde and trifluoroacetaldehyde may exist as stable equivalents such as themselves, self-polymers, hydrates, hemiacetals, acetals, and compounds having structural characteristics thereof. Therefore, in the present invention, these stable equivalents are also included in the carbonyl compounds represented by the general formula [2].

[0086] As R of the general formula [3] 4 A linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, and a halogen atom, and examples thereof include R of the general formula [1] 1 As those exemplified. 4 , preferably a halogen atom, more preferably a fluorine atom.

[0087] Specific examples of the sulfonyl isocyanate compound represented by the general formula [3] include fluorosulfonyl isocyanate (FS(═O)2N═C═O), chlorosulfonyl isocyanate (ClS(═O)2N═C═O), and the like.

[0088] The sulfonyl isocyanate compound is preferably fluorosulfonyl isocyanate (FS(═O) 2 N═C═O).

[0089] As R of the general formula [4] 5 A linear or branched alkyl group having 1 to 10 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, and examples thereof include R of the general formula [1] 1 Those exemplified, and n-heptyl, n-octyl, n-nonyl, n-decyl and the like.

[0090] Specific examples of the isocyanate compound represented by the general formula [4] include methyl isocyanate, ethyl isocyanate, n-propyl isocyanate, isopropyl isocyanate, n-butyl isocyanate, tert-butyl isocyanate and the like.

[0091] From the viewpoint of reactivity with a film containing Si and N, the isocyanate compound is preferably methyl isocyanate, ethyl isocyanate, or n-propyl isocyanate.

[0092] The treatment temperature for contacting the film formed on the substrate with the (I) HF gas is preferably 20° C. to 200° C., more preferably 30° C. to 150° C., and further preferably 40° C. to 130° C. The treatment temperature for contacting the film formed on the substrate with the compound (II) and the treatment temperature for contacting the film formed on the substrate with the (I) HF gas and the compound (II) simultaneously are also preferably the above temperatures. When the treatment temperature is within the above temperature range, the reactivity with the film containing Si and N is good, the productivity is good, and the damage to the substrate is small.

[0093] The etching method of the present invention preferably etches the film containing Si and N without a plasma state. This is because when the substrate is a semiconductor device substrate, there is a concern that the plasma gas may cause electrical damage to the substrate if it comes into contact with the plasma gas.

[0094] The etching method of the present invention is suitable for selectively etching the film containing Si and N. In the etching method of the present invention, it is preferred to selectively etch the film containing Si and N, and to etch the film containing Si and O at a rate of 1.0 nm / min or less. A rate of 0.5 nm / min or less is more preferred. The etching rate is a value calculated based on the contact time of HF gas.

[0095] In this specification, "selectively etching a film containing Si and N" means that the ratio of the etching rate of the film containing Si and N to the film containing Si and O (film containing Si and N / film containing Si and O) is 5 or more. The etching rate ratio is preferably 10 or more, more preferably 15 or more, and particularly preferably 30 or more.

[0096] In the etching method of the present invention, the substrate is preferably a semiconductor device substrate, and examples thereof include a silicon substrate, a compound semiconductor substrate, a quartz substrate, and a glass substrate. In addition to a film containing at least Si and O and a film containing at least Si and N, a polysilicon film, a film containing a metal nitride, a silicon film, a metal wiring film, and the like may be formed on the surface of the substrate. The silicon nitride film is adjacent to the silicon oxide film, and the silicon oxide film and the silicon nitride film are exposed in a manner suitable for the etching method of the present invention. The silicon nitride film is adjacent to the silicon oxide film and the polysilicon film, and the silicon oxide film, the polysilicon film, and the silicon nitride film are exposed in a manner suitable for the etching method of the present invention.

[0097] The substrate is placed on, for example, a stage of an etching apparatus described below, and the substrate and the film containing Si and O and the film containing Si and N formed on the surface of the substrate are heated by heating the stage.

[0098] The method for forming a film on the substrate surface is not particularly limited, and for example, a chemical vapor deposition (CVD) method or a sputtering method can be cited. In addition, the thickness of the film containing Si and O and the film containing Si and N is also not particularly limited, and for example, the thickness can be set to be greater than 0.1 nm and less than 1 μm.

[0099] The etching method of the present invention preferably carries out the etching by placing the substrate in a chamber. The etching method of the present invention preferably includes a step of applying a reduced pressure state to the chamber. The etching method of the present invention more preferably includes the following step: in the chamber, after the HF gas (I) and the compound (II) are brought into contact with a substrate having a film containing at least Si and O and a film containing at least Si and N, applying a reduced pressure state to the chamber. This is because byproducts generated during etching can be removed.

[0100] The reduced pressure state refers to a state in which the pressure in the chamber is lower than the pressure during etching (processing pressure), and is generally 0.133 kPa or less.

[0101] The etching method of the present invention preferably includes a step of replacing the interior of the chamber with an inert gas. The etching method of the present invention more preferably includes the following step: after the HF gas (I) is brought into contact with the compound (II), the interior of the chamber is replaced with an inert gas. This is because byproducts generated during etching can be removed.

[0102] The etching method of the present invention may include performing a step of replacing the interior of the chamber with an inert gas after performing the step of providing the interior of the chamber with a decompressed state.

[0103] For example, an oxide film and a nitride oxide film are usually formed on the surface of SiN, which is an example of a film containing Si and N. Therefore, in the etching method of the present invention, a step of removing these films can be performed before the above-mentioned (I) HF gas and the above-mentioned (II) compound are brought into contact with the substrate.

[0104] [First etching method]

[0105] First, as an etching method of the present invention, a first etching method in which the above-mentioned (I) HF gas and the above-mentioned (II) compound are brought into contact with the above-mentioned substrate at the same time is described. Hereinafter, the etching gas used in the first etching method is referred to as etching gas A, and etching gas A contains at least the above-mentioned (I) HF gas and the above-mentioned (II) compound.

[0106] In the following description, a film containing at least Si and O and a film containing at least Si and N are also referred to as an etched film.

[0107] It is speculated that if the above-mentioned etched film in a heated state is brought into contact with (I) HF gas and (II) compound at the same time, the compound (II) will directly combine with Si-NH2 on the surface of the film containing Si and N (especially SiN film), thereby suppressing the generation of NH3. It is believed that the etching of the film containing Si and O caused by NH3 is suppressed, and the film containing Si and N of the etched film can be selectively etched.

[0108] Examples of the compound (II) include the same ones as mentioned above.

[0109] The volume ratio of (I) HF gas to (II) compound is preferably HF gas: (II) compound = 10:0.01 or more and 10 or less, more preferably 10:0.01 or more and 6 or less. If the ratio of HF gas is too small, the etching rate tends to decrease, and if the ratio of HF gas is too large, the price becomes too high. In addition, even if there is too much compound (II), etching is not easy to proceed.

[0110] The compound (II) exhibits an effect even in a trace amount. Therefore, the compound (II) may be present in an amount of 1 volume ppm or more, assuming the total of HF gas, the compound (II) and the following additional gas to be 100 volume %.

[0111] The etching gas A may consist of only (I) HF gas and (II) compound, or may further contain at least one additional gas selected from the group consisting of O2, NO, N2O, CO, CO2, H2O2 and alcohol, or may further contain at least one inactive gas selected from the group consisting of N2, Ar, He, Ne and Kr. In addition, as alcohol, methanol, ethanol, propanol, isopropanol, etc. may be used.

[0112] When an additional gas is used, the total content of the additional gas can be 10% by volume to 90% by volume, assuming the total of (I) HF gas, (II) compound, the additional gas, and the inert gas is 100% by volume.

[0113] When the etching gas A contains an inert gas, the total of (I) HF gas, (II) compound, the above-mentioned additional gas, and the above-mentioned inert gas is set to 100 volume %, and the content of the inert gas contained in the etching gas A is preferably greater than 1 volume % and less than 90 volume %, more preferably greater than 10 volume % and less than 80 volume %, and further preferably greater than 30 volume % and less than 50 volume %.

[0114] The water content in the etching gas A is preferably less than 1 mass %. This is because if the water content is high, H 2 O will be generated when it evaporates, and a film containing Si and O (SiO 2 film) may be etched by HF+H 2 O.

[0115] The first etching method preferably includes: a step of bringing the HF gas (I) and the compound (II) into contact with the substrate at the same time in a chamber; and a step of applying a reduced pressure state to the chamber, and etching is performed by repeating these steps. The step of replacing the chamber with an inert gas may be performed instead of the step of applying a reduced pressure state to the chamber, or the step of replacing the chamber with an inert gas may be performed after the step of applying a reduced pressure state to the chamber. As one embodiment, in the first etching method, it is preferred that after bringing the HF gas (I) and the compound (II) into contact with the substrate at the same time in a chamber, the step of applying a reduced pressure state to the chamber and / or the step of replacing the chamber with an inert gas are performed.

[0116] [Second etching method]

[0117] Next, as an etching method of the present invention, a second etching method is described, which includes a first etching step of bringing the HF gas (I) into contact with the substrate, and a second etching step of bringing the compound (II) into contact with the substrate. Hereinafter, the etching gas used in the first etching step of the second etching method is referred to as etching gas B, and the etching gas used in the second etching step is referred to as etching gas C. Etching gas B contains at least HF gas (I), and etching gas C contains at least compound (II).

[0118] When the heated film to be etched is subjected to a second etching step, that is, an etching gas C containing the compound (II) is brought into contact with the film to be etched, protons (H + ), and the compound (II) will directly combine with Si-NH2 on the surface of the film containing Si and N (especially SiN film). Then, as a first etching step, if it is brought into contact with etching gas B containing (I) HF gas, NH3 will not be generated, and the above-mentioned film containing Si and N can be selectively etched.

[0119] In the second etching method of the present invention, the above steps may be repeated multiple times in order to repeatedly etch the film to be etched. In one cycle of the etching step, a fixed thickness can be etched, so by specifying the number of cycles, a layer of a desired thickness can be precisely etched.

[0120] As the compound of (II), the same ones as mentioned above can be used.

[0121] The etching gas B may consist of only (I) HF gas, and the etching gas C may consist of only (II) compound. The etching gas B and the etching gas C may further contain at least one additional gas selected from the group consisting of O2, NO, N2O, CO, CO2, H2O2 and alcohol. The etching gas B and the etching gas C may further contain at least one inactive gas selected from the group consisting of N2, Ar, He, Ne and Kr. In addition, as alcohol, methanol, ethanol, propanol, isopropanol, etc. can be used.

[0122] When the etching gas B contains an additive gas, the total of (I) HF gas, the above-mentioned additive gas, and the above-mentioned inert gas is set to 100 volume%, and the total content of the additive gas contained in the etching gas B can be set to more than 10 volume% and less than 90 volume%.

[0123] In addition, when the etching gas C contains an additive gas, the total content of the compound (II), the above-mentioned additive gas, and the above-mentioned inert gas is set to 100 volume%, and the total content of the additive gas contained in the etching gas C can be set to more than 10 volume% and less than 90 volume%.

[0124] When the etching gas B contains an inert gas, the total of (I) HF gas, the above-mentioned additional gas, and the above-mentioned inert gas is set to 100 volume %, and the content of the inert gas contained in the etching gas B is preferably greater than 1 volume % and less than 90 volume %, more preferably greater than 10 volume % and less than 80 volume %, and further preferably greater than 30 volume % and less than 50 volume %.

[0125] When the etching gas C contains an inert gas, the total of the compound (II), the above-mentioned additional gas, and the above-mentioned inert gas is set to 100 volume%, and the content of the inert gas contained in the etching gas C is preferably greater than 1 volume % and less than 90 volume %, more preferably greater than 10 volume % and less than 80 volume %, and further preferably greater than 30 volume % and less than 50 volume %.

[0126] The water content in the etching gas B and the water content in the etching gas C are preferably less than 1 mass %. This is because if the water content is high, H2O will be generated when it evaporates, and the film containing Si and O (SiO2 film) may be etched by HF+H2O.

[0127] The second etching method preferably includes a first etching process and a second etching process in the chamber, and then a process of imparting a reduced pressure state to the chamber. Etching is preferably performed by repeating these processes. Instead of the process of imparting a reduced pressure state to the chamber, a process of replacing the chamber with an inert gas may be performed, or the process of replacing the chamber with an inert gas may be performed after the process of imparting a reduced pressure state to the chamber. As one embodiment, in the second etching method, it is preferred that after performing the second etching process, a process of imparting a reduced pressure state to the chamber and / or a process of replacing the chamber with an inert gas is performed, and then after performing the first etching process, a process of imparting a reduced pressure state to the chamber and / or a process of replacing the chamber with an inert gas is performed.

[0128] In addition, one of the present inventions is an etching method for etching the film containing Si and N by bringing a substrate having a polycrystalline silicon film and a film containing at least Si and N into contact with (I) HF gas and (II) at least one compound selected from the group consisting of a sulfonyl compound represented by the general formula [1], a carbonyl compound represented by the general formula [2], a sulfonyl isocyanate compound represented by the general formula [3], and an isocyanate compound represented by the general formula [4].

[0129] In addition to the polysilicon film and the film containing at least Si and N, a film containing at least Si and O, a film containing a metal nitride, a silicon film, a metal wiring film, etc. may be formed on the surface of the above-mentioned substrate.

[0130] The compound (II) in contact with the substrate and the etching conditions may be the same as those in the etching method for the substrate having the film containing at least Si and O and the film containing at least Si and N described above.

[0131] [Etching equipment]

[0132] The etching method of the present invention can be realized by using, for example, the following etching apparatus. Such an etching apparatus is also one of the present invention.

[0133] The etching apparatus of the present invention comprises: a mounting table on which a substrate is mounted; an HF gas supply unit for supplying the above-mentioned (I) HF gas; and a gas compound (II) supply unit for supplying (II) a gas of at least one compound selected from the group consisting of a sulfonyl compound represented by the general formula [1], a carbonyl compound represented by the general formula [2], a sulfonyl isocyanate compound represented by the general formula [3], and an isocyanate compound represented by the general formula [4] (hereinafter also referred to as gas compound (II)). The etching apparatus of the present invention may further comprise an inert gas supply unit for supplying an inert gas into the above-mentioned chamber.

[0134] Figure 1This is a schematic diagram schematically showing an etching device according to one embodiment of the present invention.

[0135] Figure 1 The etching apparatus 100 shown in the figure includes: a chamber 110 in which a substrate 113 is arranged; an HF gas supply unit 140 connected to the chamber 110 to supply HF gas; a gas compound (II) supply unit 150 to supply the gas compound (II); an inert gas supply unit 130 to supply an inert gas; and a heating unit 111 to heat the chamber 110. It should be noted that the etching apparatus 100 may not include the inert gas supply unit 130.

[0136] The etching device 100 also includes a control unit (not shown). The control unit includes, for example, a computer, which includes a program, a memory, and a CPU. The program includes a process group for implementing a series of actions in the first etching method or the second etching method. According to the program, the temperature of the substrate 113 is adjusted, the valves of each supply unit are opened and closed, the flow rate of each gas is adjusted, the pressure in the chamber 110 is adjusted, etc. are adjusted. The program is stored in a computer storage medium, such as an optical disk, a hard disk, a magneto-optical disk, a memory card, etc., and is installed in the control unit.

[0137] The chamber 110 includes a mounting table 112 for mounting a substrate 113. The chamber 110 is not particularly limited as long as it is resistant to the HF gas used and can be decompressed to a predetermined pressure, and a general chamber provided in a semiconductor etching device can be generally applied. In addition, a supply pipe and other piping for supplying etching gas are not particularly limited, and general supply pipes or piping can be used as long as they are resistant to HF gas.

[0138] The HF gas supply unit 140 adjusts the supply amount by means of valves 143 and 144 and a flow rate adjustment unit 142 , and supplies the HF gas from the pipes 141 and 145 to the pipe 121 .

[0139] The gaseous compound (II) supply unit 150 adjusts the supply amount by means of valves 153 and 154 and a flow rate adjustment unit 152 , and supplies the gaseous compound (II) from pipes 151 and 155 to the pipe 121 .

[0140] The inert gas supply unit 130 adjusts the supply amount by means of valves 133 and 134 and a flow rate adjustment unit 132 , and supplies the inert gas from pipes 131 and 135 to the pipe 121 .

[0141] A heating unit 111 for heating the chamber 110 is disposed outside the chamber 110. In addition, a heater (not shown) may also be provided inside the mounting table 112 as a second heating unit. It should be noted that when a plurality of mounting tables are disposed in the chamber 110, by providing each mounting table with a heater, the temperature of the substrate on each mounting table can be set to a predetermined temperature.

[0142] A gas exhaust unit for exhausting the gas after the reaction is disposed at one end of the chamber 110. The gas after the reaction is exhausted from the chamber 110 through the pipe 122 by the vacuum pump 127 of the gas exhaust unit. A liquid nitrogen trap (not shown) may be disposed between the pipe 122 and the vacuum pump 127 to recover the gas after the reaction. Valves 125 and 126 may be disposed in the pipes 121 and 122 to adjust the pressure. In addition, Figure 1 In the figure, PI123 and 124 are pressure gauges, and based on their indicated values, the control unit can control each flow regulating unit and each valve.

[0143] Taking the etching device 100 as an example, the etching method is described in detail.

[0144] [First etching method using the above etching apparatus]

[0145] In the first etching method of the present invention, etching gas A containing (I) HF gas and the compound (II) is brought into contact with a film to be etched.

[0146] In the first etching method, first, a substrate 113 having an etched film formed thereon, the etched film including a film containing at least Si and O and a film containing at least Si and N, is disposed in a chamber 110. Next, after the interior of the chamber 110, pipes 121 and 122, pipes 131 and 135, pipes 141 and 145, and pipes 151 and 155 are evacuated to a predetermined pressure by a vacuum pump 127, the substrate 113 is heated by a heating unit 111.

[0147] After the substrate 113 reaches a predetermined temperature, HF gas and gas compound (II) are supplied to the pipe 121 at a predetermined flow rate from the HF gas supply unit 140 and the gas compound (II) supply unit 150. It should be noted that the inert gas supply unit 130 may also supply the inert gas to the pipe 121 at a predetermined flow rate.

[0148] HF gas and gas compound (II) are mixed in a predetermined composition and supplied to the chamber 110. The mixed etching gas is introduced into the chamber 110 while the pressure in the chamber 110 is controlled to be predetermined. Etching is performed by reacting the etching gas A with the film to be etched for a predetermined time. In this etching method, etching can be performed in a plasma-free state without a plasma state, and during etching, it is not necessary to excite the etching gas A with plasma or the like. The flow rate of the etching gas A can be appropriately set based on the volume and pressure of the chamber.

[0149] It should be noted that etching in a plasma state refers to, for example, introducing a gas of about 0.01 to 1.33 kPa into the interior of the reaction device, applying high-frequency power to the outer coil or electrode, so that a low-temperature gas plasma is generated in the reaction device, thereby etching through active chemical species such as ions and free radicals generated therein.

[0150] In the etching method of the present invention, dry etching is performed without contacting the gas in a plasma state and without generating the gas plasma.

[0151] After the etching process is completed, the heating by the heating unit 111 is stopped to cool down, and the vacuum pump 127 is stopped to replace the vacuum with an inert gas. As described above, the first etching method using the etching apparatus can selectively etch the film containing Si and N of the etched film.

[0152] (Etching Conditions in the First Etching Method)

[0153] In the first etching method of the present invention, the temperature of the etched film when the etching gas A is brought into contact with the above-mentioned etched film only needs to be the temperature at which the etching gas A reacts with the film containing Si and N (SiN film). In particular, the temperature of the etched film to be removed is preferably above 20°C and below 200°C, more preferably above 30°C and below 150°C, and further preferably above 40°C and below 130°C.

[0154] When the film to be etched is brought into contact with the etching gas A, the pressure in the chamber where the substrate on which the film to be etched is formed is not particularly limited, but is generally within a pressure range of 0.01 kPa to 101.3 kPa.

[0155] From the viewpoint of obtaining a sufficient etching rate, the pressure in the chamber during the etching step is preferably 0.01 kPa to 101.3 kPa, more preferably 0.1 kPa to 50 kPa, and further preferably 1 kPa to 20 kPa.

[0156] The processing time of the etching process is not particularly limited, but is preferably within 60 minutes in consideration of the efficiency of semiconductor device processing. Here, the processing time of the etching process refers to the time from the introduction of etching gas A into the chamber where the substrate is disposed to the time when the etching gas A in the chamber is exhausted by a vacuum pump or the like in order to end the etching process.

[0157] [Second etching method using the above etching apparatus]

[0158] The second etching method of the present invention includes a first etching step of bringing an etching gas B containing HF gas into contact with a film to be etched, and a second etching step of bringing an etching gas C containing the compound (II) into contact with the film to be etched.

[0159] In the second etching method, first, a substrate 113 formed with a film containing at least Si and O and a film containing at least Si and N is disposed in a chamber 110. Next, the interior of the chamber 110, pipes 121 and 122, pipes 131 and 135, pipes 141 and 145, and pipes 151 and 155 are evacuated to a predetermined pressure by a vacuum pump 127, and then the substrate 113 is heated by a heating unit 111.

[0160] After the substrate 113 reaches a predetermined temperature, the gas compound (II) is initially supplied from the gas compound (II) supply unit 150 to the pipe 121 at a predetermined flow rate. It should be noted that the inert gas may also be supplied from the inert gas supply unit 130 to the pipe 121 at a predetermined flow rate. The pressure in the chamber 110 is controlled to be predetermined while the gas compound (II) or the gas compound (II) and the inert gas are introduced into the chamber 110. By introducing the gas compound (II) into the chamber 110 for a predetermined time, the gas compound (II) is adsorbed on the film to be etched.

[0161] After the gas containing the gas compound (II) is evacuated, the HF gas is supplied to the pipe 121 at a predetermined flow rate from the HF gas supply unit 140. It should be noted that the inert gas may also be supplied to the pipe 121 at a predetermined flow rate from the inert gas supply unit 130. While the HF gas, or the HF gas and the inert gas are introduced into the chamber 110, the pressure in the chamber 110 is controlled to be a predetermined pressure. By introducing the HF gas into the chamber 110 for a predetermined time, the film containing Si and N of the above-mentioned etched film can be selectively etched.

[0162] In the second etching method of the present invention, a plurality of cycles of the first etching step of introducing HF gas into the chamber 110 and the second etching step of introducing the gaseous compound (II) into the chamber 110 may be repeated.

[0163] In the second etching method of the present invention, by setting the etching conditions of one cycle to specified conditions, the thickness of the etched film that can be etched in one cycle can be controlled. Therefore, by setting the thickness of the etched film that can be etched in one cycle to be thinner, the etching thickness can be precisely controlled.

[0164] In the second etching method of the present invention, preferably, after the second etching step, a step of providing a reduced pressure state in the chamber is performed, and then the first etching step is performed. In addition, preferably, the step of providing a reduced pressure state in the chamber is performed every cycle.

[0165] It should be noted that the second etching method can also be carried out in a plasma-free state without a plasma state, and during etching, there is no need to excite the etching gas with plasma, etc. The flow rates of the HF gas and the gas compound (II) can be appropriately set based on the volume and pressure of the chamber.

[0166] As described above, in the second etching method of the present invention using the etching apparatus, the gas can be contacted without being in a plasma state, and dry etching can be performed without generating the gas plasma.

[0167] After the etching process is completed, the heating by the heating unit 111 is stopped to cool down, and the vacuum pump 127 is stopped to replace the vacuum with an inert gas. The second etching method using the etching apparatus can selectively etch a film containing Si and N of the etched film.

[0168] (Etching Conditions in the Second Etching Method)

[0169] In the second etching method of the present invention, the temperature of the film to be etched during the etching process can be any temperature at which the etching gas B reacts with the film containing Si and N (SiN film), and the etching gas C reacts with the film containing Si and N (SiN film). In particular, the temperature of the film to be etched as the object of removal is preferably 20° C. to 200° C., more preferably 30° C. to 150° C., and further preferably 40° C. to 130° C. The temperature of the film to be etched in the first etching process and the second etching process is preferably the same.

[0170] The pressure in the chamber during the etching process is not particularly limited, but is generally within a pressure range of 0.01 kPa to 101.3 kPa.

[0171] From the viewpoint of obtaining a sufficient etching rate, the pressure in the chamber in the first etching step and the second etching step is preferably 0.01 kPa or more and 101.3 kPa or less, more preferably 0.1 kPa or more and 50 kPa or less, and further preferably 1 kPa or more and 20 kPa or less. The pressure in the chamber in the second etching step is preferably higher than the pressure in the chamber in the first etching step.

[0172] The processing time in the first etching step and the second etching step is not particularly limited, and the processing time of one cycle of the first etching step is preferably within 60 minutes, and the processing time of one cycle of the second etching step is preferably within 60 minutes. Here, the processing time of the etching step refers to the time from the introduction of etching gas into the chamber where the substrate is placed to the exhaustion of the etching gas in the chamber by a vacuum pump or the like in order to end the etching process.

[0173] [Method for manufacturing semiconductor device]

[0174] The etching method of the present invention can be used as a method for selectively etching the silicon nitride film by applying the etching method to a substrate having a silicon nitride film and a silicon oxide film. By selectively etching the silicon nitride film on the substrate using the etching method of the present invention, semiconductor devices can be manufactured at low cost.

[0175] The method for manufacturing a semiconductor device of the present invention is characterized in that it comprises a step of selectively etching the silicon nitride film by applying the above-mentioned etching method to a substrate having a silicon nitride film and a silicon oxide film. The step of selectively etching the silicon nitride film without plasma state by reacting the above-mentioned substrate having a silicon nitride film and a silicon oxide film with HF gas and the compound (II) can be performed by the above-mentioned etching method of the present invention. The above-mentioned substrate may also have a polysilicon film. The above-mentioned substrate is preferably a silicon substrate.

[0176] [Etching gas]

[0177] An etching gas comprising (I) HF gas and (II) at least one compound selected from the group consisting of a sulfonyl compound represented by the general formula [1], a carbonyl compound represented by the general formula [2], a sulfonyl isocyanate compound represented by the general formula [3], and an isocyanate compound represented by the general formula [4] is also one of the present invention. The etching gas of the present invention may also be in the same form as the etching gas A. That is, the etching gas of the present invention is a mixture comprising at least the above-mentioned (I) HF gas and the above-mentioned compound (II).

[0178] Example

[0179] Hereinafter, the present invention will be described in detail by way of Examples, but the present invention is not limited to these Examples.

[0180] First, as the substrate to be processed, a silicon wafer with a SiN film formed thereon, a silicon wafer with a SiO2 film formed thereon, and a silicon wafer with a polycrystalline silicon (p-Si) film formed thereon were prepared respectively. A spectroscopic ellipsometer (manufactured by Semilab Japan KK, product name: SE-2000) was used to measure the film thickness of the substrate to be processed before and after etching, and the etching amount and the selectivity of SiN to SiO2 and p-Si (SiN / SiO2 selectivity and SiN / p-Si selectivity) were obtained.

[0181] [Example 1]

[0182] use Figure 1 The etching device 100 shown. First, a substrate to be processed is placed on a stage in a chamber, and after the chamber is fully evacuated, the temperature of the stage is set to 120°C. The temperature of the substrate is the same as the temperature of the stage, which is substantially equal to the temperature of the film to be etched. Next, N2 gas is circulated in the chamber to make it fully dry. After that, HF gas and CF3S(=O)2F (trifluoromethanesulfonyl fluoride) gas are circulated in the chamber for 1 minute. The gas flow rate at this time is set to HF gas = 200sccm, CF3S(=O)2F gas = 100sccm, and the pressure in the chamber is set to 6.66kPa. Finally, the chamber is evacuated, replaced with N2 gas, and the substrate to be processed is taken out. The results are shown in Table 1. As the substrate to be processed, a silicon wafer with a SiN film, a silicon wafer with a SiO2 film, and a silicon wafer with a polycrystalline silicon (p-Si) film are all placed in the same chamber and etched at the same time.

[0183] [Example 2]

[0184] The test was conducted under the same conditions as in Example 1 except that HF ​​gas and CF3C(=O)CF3 (hexafluoroacetone) gas were flowed for 15 minutes instead of HF gas and CF3S(=O)2F gas. The results are shown in Table 1.

[0185] [Example 3]

[0186] The test was conducted under the same conditions as in Example 1 except that HF ​​gas and FS(═O)2N═C═O (fluorosulfonyl isocyanate) gas were flowed for 15 minutes instead of HF gas and CF3S(═O)2F gas. The results are shown in Table 1.

[0187] [Example 4]

[0188] The test was conducted under the same conditions as in Example 1 except that HF ​​gas and S(═O) 2 F 2 (sulfonyl fluoride) gas were flowed for 15 minutes instead of HF gas and CF 3 S(═O) 2 F gas. The results are shown in Table 1.

[0189] [Comparative Example 1]

[0190] The test was conducted under the same conditions as in Example 1 except that HF ​​gas and N2 gas were flowed for 10 minutes instead of HF gas and CF3S(=O)2F gas. The results are shown in Table 1.

[0191] [Example 5]

[0192] First, a substrate to be processed is placed on a stage in a chamber, and after the chamber is fully evacuated, the temperature of the stage is set to 120° C. Next, N 2 gas is flowed in the chamber to fully dry the substrate.

[0193] (A) After that, CF3S(=O)2F gas is circulated in the chamber, and then fully evacuated and replaced with N2 gas. The gas flow rate at this time is set to CF3S(=O)2F gas = 100 sccm, the pressure is set to 6.66 kPa, and the CF3S(=O)2F gas circulation time is set to 2 minutes.

[0194] (B) Next, HF gas is circulated in the chamber while being diluted with N2 gas, and then fully evacuated and replaced with N2 gas. The gas flow rate at this time is set to HF gas = 200 sccm, N2 gas = 100 sccm, the pressure is set to 6.66 kPa, and the HF gas / N2 gas circulation time is set to 1 minute.

[0195] Here, cyclic etching is performed by repeating (A) and (B) 10 times. Finally, the processed substrate is taken out from the chamber. The results are shown in Table 2. It should be noted that the etching rate is calculated based on the HF gas / N2 gas flow time.

[0196] [Example 6]

[0197] The test was conducted under the same conditions as in Example 1 except that the pressure in the chamber was set to 5.3 kPa and HF gas and CF3S(=O)2F gas were circulated for 3 minutes. The results are shown in Table 3.

[0198] [Example 7]

[0199] The test was conducted under the same conditions as in Example 1 except that the temperature of the mounting table was set to 50° C. and HF gas and CF 3 S(═O) 2 F gas were circulated for 3 minutes. The results are shown in Table 3.

[0200] [Example 8]

[0201] The test was conducted under the same conditions as in Example 7 except that the pressure in the chamber was set to 4.00 kPa and HF gas and CF3S(=O)2F gas were allowed to flow. The results are shown in Table 3.

[0202] [Example 9]

[0203] The test was conducted under the same conditions as in Example 7 except that the pressure in the chamber was set to 2.00 kPa and HF gas and CF3S(=O)2F gas were allowed to flow. The results are shown in Table 3.

[0204] [Example 10]

[0205] The test was conducted under the same conditions as in Example 1 except that the temperature of the mounting table was set to 30° C. and HF gas and CF 3 S(═O) 2 F gas were circulated for 3 minutes. The results are shown in Table 3.

[0206] [Example 11]

[0207] The test was conducted under the same conditions as in Example 10 except that the pressure in the chamber was set to 4.00 kPa and HF gas and CF3S(=O)2F gas were allowed to flow. The results are shown in Table 3.

[0208] [Example 12]

[0209] The test was conducted under the same conditions as in Example 10 except that the pressure in the chamber was set to 2.00 kPa and HF gas and CF3S(=O)2F gas were allowed to flow. The results are shown in Table 3.

[0210] [Comparative Example 2]

[0211] The test was conducted under the same conditions as in Example 6 except that the pressure in the chamber was set to 13.33 kPa and HF gas and N2 gas were circulated for 30 minutes instead of HF gas and CF3S(=O)2F gas. The results are shown in Table 3.

[0212] [Comparative Example 3]

[0213] The test was conducted under the same conditions as in Example 6 except that the pressure in the chamber was set to 4.00 kPa and HF gas and N2 were circulated for 30 minutes instead of HF gas and CF3S(=O)2F gas. The results are shown in Table 3.

[0214] [Table 1]

[0215]

[0216] [Table 2]

[0217]

[0218] [Table 3]

[0219]

[0220] Table 1 shows the flow conditions of each gas and the results of the etching rate of the substrate to be processed, the SiN / SiO2 selectivity ratio, and the SiN / p-Si selectivity ratio of Examples 1 to 4 and Comparative Example 1. Table 2 shows the flow conditions of each gas and the results of the etching rate of the substrate to be processed, the SiN / SiO2 selectivity ratio, and the SiN / p-Si selectivity ratio of Example 5. Table 3 shows the flow conditions of each gas and the results of the etching rate of the substrate to be processed, the SiN / SiO2 selectivity ratio, and the SiN / p-Si selectivity ratio of Examples 6 to 12 and Comparative Examples 2 to 3.

[0221] The etching rate of the SiO2 film was 0.0 to 0.2 nm in Examples 1 to 12, whereas it was ≥ 1.0 nm in Comparative Examples 1 to 3. In Examples 1 to 12, the etching of the SiO2 film was suppressed.

[0222] Regarding the SiN / SiO2 selection ratio, Examples 1, 3, 5, 8 to 9 and 11 to 12 are ∞, Example 2 is 36, Example 4 is 18, Example 6 is 47, Example 7 is 73, and Example 10 is 32.

[0223] In addition, regarding the SiN / p-Si selectivity, the selectivity was ∞ in Examples 1 to 12. In Comparative Example 1, the SiN / p-Si selectivity was ∞ and the SiN / SiO2 selectivity was 1.9, but as a result, the SiO2 surface was etched.

[0224] From the results of Examples 1 to 12 above, it can be seen that by circulating a compound (II) such as HF gas and CF3S(=O)2F gas, it is possible to suppress the etching of SiO2 and p-Si and to etch SiN.

[0225] Description of Reference Numerals

[0226] 100 Etching Device

[0227] 110 Chamber

[0228] 111 Heating unit

[0229] 112 Loading table

[0230] 113 base plate

[0231] 121, 122 Piping

[0232] 123, 124PI (pressure gauge)

[0233] 125, 126 valve

[0234] 127 Vacuum Pump

[0235] 130 Inert gas supply unit

[0236] 131, 135 piping

[0237] 132 Flow regulation unit

[0238] 133, 134 valve

[0239] 140 HF gas supply unit

[0240] 141, 145 piping

[0241] 142 Flow regulation unit

[0242] 143, 144 valve

[0243] 150 Gas compound (II) supply unit

[0244] 151, 155 piping

[0245] 152 Flow regulation unit

[0246] 153, 154 valve

Claims

1. An etching method, wherein: A substrate having a film containing at least Si and O and a film containing at least Si and N is brought into contact with (I) HF gas and (II) at least one compound selected from the group consisting of a sulfonyl compound represented by the following general formula [1], a carbonyl compound represented by the following general formula [2], a sulfonyl isocyanate compound represented by the following general formula [3], and an isocyanate compound represented by the following general formula [4], thereby etching the film containing Si and N, R 1 -S(=O)2-X[1] In the general formula [1], R 1 is a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, or a halogen atom, X is a halogen atom, R 2 -C(=O)-R 3 [2] In the general formula [2], R 2 and R 3 Each independently represents a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, a hydrogen atom, a halogen atom, or an isocyanate group, R 4 -S(=O)2N=C=O[3] In the general formula [3], R 4 is a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, or a halogen atom, R 5 -N=C=O[4] In the general formula [4], R 5 It is a linear or branched alkyl group having 1 to 10 carbon atoms in which a part or all of the hydrogen atoms may be substituted with fluorine atoms.

2. The etching method according to claim 1, wherein: The film containing Si and N is etched without a plasma state.

3. The etching method according to claim 1, characterized in that: The film including Si and N is selectively etched.

4. The etching method according to claim 1, wherein: The etching is performed selectively on the film containing Si and N, and the etching on the film containing Si and O is performed at a rate of 1.0 nm / min or less.

5. The etching method according to claim 1, wherein: R of the general formula [1] 1 is a fluoroalkyl group or a fluorine atom, and X is a fluorine atom.

6. The etching method according to claim 1, wherein: The sulfonyl compound represented by the general formula [1] is trifluoromethanesulfonyl fluoride (CF3S(=O)2F) or sulfonyl fluoride (SO2F2).

7. The etching method according to claim 1, wherein: The carbonyl compound represented by the general formula [2] is hexafluoroacetone (CF3C(=O)CF3), trifluoroacetaldehyde (CF3C(=O)H), or fluorocarbonyl isocyanate (FC(=O)N=C=O).

8. The etching method according to claim 1, wherein: The isocyanate compound represented by the general formula [3] is fluorosulfonyl isocyanate (FS(═O)2N═C═O). 9 . The etching method according to claim 1 , comprising the step of placing the substrate in a chamber to perform the etching, and applying a reduced pressure to the chamber.

10. The etching method according to claim 1, wherein: The (I) HF gas and the (II) compound are brought into contact with the substrate simultaneously.

11. The etching method according to claim 1, comprising: A first etching step of bringing the (I) HF gas into contact with the substrate, and a second etching step of bringing the (II) compound into contact with the substrate. 12 . The etching method according to claim 11 , wherein etching is performed by repeatedly performing the first etching step and the second etching step.

13. The etching method according to claim 11, wherein: After the second etching process is performed, the first etching process is then performed.

14. The etching method according to claim 1, wherein: The film containing Si and O is a silicon oxide (SiO 2 ) film.

15. The etching method according to claim 1, wherein: The film including Si and N is a silicon nitride (SiN) film.

16. The etching method according to claim 1, wherein: In the substrate, the film containing Si and O is a silicon oxide (SiO2) film, the film containing Si and N is a silicon nitride (SiN) film, the silicon nitride film is adjacent to the silicon oxide film, and the silicon oxide film and the silicon nitride film are exposed.

17. A method for manufacturing a semiconductor device, comprising: A step of applying the etching method according to any one of claims 1 to 15 to a substrate having a silicon nitride film and a silicon oxide film to selectively etch the silicon nitride film.

18. An etching device comprising: a mounting table on which a substrate is mounted; an HF gas supply unit that supplies (I) HF gas; and a gaseous compound (II) supplying unit, which supplies (II) a gas of at least one compound selected from the group consisting of a sulfonyl compound represented by the following general formula [1], a carbonyl compound represented by the following general formula [2], a sulfonyl isocyanate compound represented by the following general formula [3], and an isocyanate compound represented by the following general formula [4], R 1 -S(=O)2-X[1] In the general formula [1], R 1 is a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, or a halogen atom, X is a halogen atom, R 2 -C(=O)-R 3 [2] In the general formula [2], R 2 and R 3 Each independently represents a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, a hydrogen atom, a halogen atom, or an isocyanate group, R 4 -S(=O)2N=C=O[3] In the general formula [3], R 4 is a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, or a halogen atom, R 5 -N=C=O[4] In the general formula [4], R 5 It is a linear or branched alkyl group having 1 to 10 carbon atoms in which a part or all of the hydrogen atoms may be substituted with fluorine atoms.

19. An etching gas comprising: (I) HF gas; and (II) at least one compound selected from the group consisting of a sulfonyl compound represented by the general formula [1], a carbonyl compound represented by the general formula [2], a sulfonyl isocyanate compound represented by the general formula [3], and an isocyanate compound represented by the general formula [4], R 1 -S(=O)2-X[1] In the general formula [1], R 1 is a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, or a halogen atom, X is a halogen atom, R 2 -C(=O)-R3[2] In the general formula [2], R 2 and R 3 Each independently represents a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, a hydrogen atom, a halogen atom, or an isocyanate group, R 4 -S(=O)2N=C=O[3] In the general formula [3], R 4 is a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms are optionally substituted with fluorine atoms, or a halogen atom, R 5 -N=C=O[4] In the general formula [4], R 5 It is a linear or branched alkyl group having 1 to 10 carbon atoms in which a part or all of the hydrogen atoms may be substituted with fluorine atoms.

Images