Etching methods, semiconductor device manufacturing methods, etching apparatus and etching gases

Abstract

The object of the present invention is to provide a technique for suppressing the etching of the film containing at least Si and O, and simultaneously etching the film containing at least Si and N, in a substrate having a film containing at least Si and O and a film containing at least Si and N. The etching method of the present invention involves contacting a substrate having a film containing at least Si and O and a film containing at least Si and N 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 general formula [1], R) 1-series: alkyl groups or halogen atoms with 1 to 6 carbon atoms whose hydrogen atoms can be partially or completely replaced by fluorine atoms (X-series: halogen atoms). R 2-C(=O)-R 3[2] (in general formula [2], R) 2 and R 3 are, independently, straight-chain or branched alkyl groups, hydrogen atoms, halogen atoms, or isocyanate groups having 1 to 6 carbon atoms, in which some or all of the hydrogen atoms can be replaced by fluorine atoms. R 4-S(=O) 2N=C=O [3] (in general formula [3], R) (4-series alkyl or halogen atoms with 1 to 6 carbon atoms whose hydrogen atoms can be partially or completely replaced by fluorine atoms) R 5-N=C=O [4] (in general formula [4], R) 5-series alkyl groups with 1 to 10 carbon atoms, in which some or all of the hydrogen atoms can be replaced by fluorine atoms (straight-chain or branched alkyl groups).

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 sulfonyl compounds, carbonyl compounds, isocyanate sulfonyl compounds, and isocyanate compounds. Prior Art

[0002] In the manufacture of semiconductor devices, the following step is sometimes performed: on a single crystal silicon substrate, silicon nitride (SiN) is selectively etched from a structure adjacent to silicon oxide (SiO2).

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

[0004] For example, Patent Document 1 describes a dry etching method for selectively plasma etching SiN in the presence of SiO2, metal silicide, or silicon, using an etching gas containing a compound represented by the formula: CHxF4-x (x represents 2 or 3) and oxygen. Patent Document 1 describes selectively etching the SiN film through the opening in the SiO2 film, using the underlying p-Si film 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 heating environment. However, when etching the SiN film with HF gas, the SiO2 film may also be etched due to HF and the NH3 reaction product, which may not improve the SiN / SiO2 selectivity.

[0007] Patent Document 3 describes a method for etching SiN films with high selectivity relative to SiO2 films using a mixed gas of HF and a fluorinated carboxylic acid. The fluorinated carboxylic acid is described as having the following properties: it captures NH3, a byproduct of HF etching of the SiN film, thereby preventing the SiO2 film from being etched, while also not hindering HF etching of the SiN film. [Prior Art Literature] [Patent Document]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 8-59215 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-187105 [Patent Document 3] Japanese Patent Application Laid-Open No. 2019-91890 Summary of the Invention

[0009] [Problems to be solved by the invention]

[0010] 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 the film containing at least Si and O and the film containing at least Si and N. [Technical means to solve the problem]

[0011] The present inventors conducted intensive research and discovered that sulfonyl compounds, carbonyl compounds, sulfonyl isocyanate compounds, or isocyanate compounds can bond with Si-NH₂ on the surface of a SiN film, thereby preventing the generation of NH₃, a by-product of the reaction between HF and SiN. Furthermore, the SiN film can be etched using this combination with HF, thereby resolving the aforementioned issues and completing the present invention.

[0012] The method described in Patent Document 3 uses a fluorinated carboxylic acid and the resulting by-product NH₃ to form a salt, trapping NH₃ and thereby inhibiting SiO₂ film etching. Meanwhile, the sulfonyl compound, carbonyl compound, sulfonyl isocyanate compound, and isocyanate compound of the present invention directly bond with Si-NH₂ on the SiN film surface without releasing protons (H₄), thereby fundamentally inhibiting NH₃ generation itself. Therefore, it is speculated that the etching inhibition effect on SiO₂ films is further enhanced.

[0013] That is, the present invention provides an etching method, a method for manufacturing a semiconductor element, and an etching device as described below [1] to

[18] . [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], an isocyanate sulfonyl 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. R 1-S(=O) 2-X [1] (In the general formula [1], R1 is a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms may be substituted by fluorine atoms, or a halogen atom. X is a halogen atom) R 2-C(=O)-R 3[2] (In the general formula [2], R2 and R3 are each independently a linear or branched alkyl group having 1 to 6 carbon atoms, in which a part or all of the hydrogen atoms may be substituted by 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], R4 is a linear or branched alkyl group having 1 to 6 carbon atoms, in which some or all of the hydrogen atoms may be substituted by fluorine atoms, or a halogen atom) R 5-N=C=O [4] (In the general formula [4], R 5 is a linear or branched alkyl group having 1 to 10 carbon atoms in which some or all of the hydrogen atoms may be substituted by fluorine atoms) [2] The etching method described in [1] above, wherein the film containing Si and N is etched without using a plasma state. [3] The etching method described in [1] or [2] above is characterized in that the film containing Si and N is selectively etched. [4] The etching method as described in [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 speed of less than 1.0 nm / min. [5] The etching method as described in any one of [1] to [4] above, wherein R 1 in the general formula [1] is a fluoroalkyl group or a fluorine atom, and X is a fluorine atom. [6] An etching method as described in 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). [7] An etching method as described in 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). [8] An etching method as described in 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). [9] An etching method as described in any one of [1] to [8] above, wherein the etching is performed by placing the substrate in a chamber, and includes a step of applying a reduced pressure to the chamber.

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

[11] The etching method as described in any one of [1] to [9] above, comprising a first etching step of bringing the above-mentioned (I) HF gas into contact with the above-mentioned substrate, and a second etching step of bringing the above-mentioned (II) compound into contact with the above-mentioned substrate.

[12] The etching method as described in

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

[13] The etching method described in

[11] or

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

[14] An etching method as described in any one of [1] to

[13] above, wherein the film containing Si and O is a silicon oxide (SiO2) film.

[15] An etching method as described in any one of [1] to

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

[16] An etching method as described in any one of [1] to

[13] above, wherein in the above-mentioned substrate, the film containing Si and O is a silicon oxide (SiO2) film, the above-mentioned 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 applying an etching method as described in any one of [1] to

[16] above 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 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 following general formula [1], a carbonyl compound represented by the following general formula [2], an isocyanate sulfonyl 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], R1 is a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms may be substituted by fluorine atoms, or a halogen atom. X is a halogen atom) R 2-C(=O)-R 3[2] (In the general formula [2], R2 and R3 are each independently a linear or branched alkyl group having 1 to 6 carbon atoms, in which a part or all of the hydrogen atoms may be substituted by 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], R4 is a linear or branched alkyl group having 1 to 6 carbon atoms, in which some or all of the hydrogen atoms may be substituted by fluorine atoms, or a halogen atom) R 5-N=C=O [4] (In the general formula [4], R 5 is a linear or branched alkyl group having 1 to 10 carbon atoms in which some or all of the hydrogen atoms may be substituted by 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 following general formula [1], a carbonyl compound represented by the following general formula [2], an isocyanate sulfonyl 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], R1 is a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms may be substituted by fluorine atoms, or a halogen atom. X is a halogen atom) R 2-C(=O)-R 3[2] (In the general formula [2], R2 and R3 are each independently a linear or branched alkyl group having 1 to 6 carbon atoms, in which a part or all of the hydrogen atoms may be substituted by 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], R4 is a linear or branched alkyl group having 1 to 6 carbon atoms, in which some or all of the hydrogen atoms may be substituted by fluorine atoms, or a halogen atom) R 5-N=C=O [4] (In the general formula [4], R 5 is a linear or branched alkyl group having 1 to 10 carbon atoms in which some or all of the hydrogen atoms may be substituted by fluorine atoms) [Effects of the Invention]

[0014] 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 the general formula [1], a carbonyl compound represented by the general formula [2], an isocyanate sulfonyl compound represented by the general formula [3], and an isocyanate compound represented by the general formula [4] for a substrate having a film containing at least Si and O and a film containing at least Si and N, the etching gas can suppress the etching of the film containing at least Si and O while etching the film containing at least Si and N. Simple diagram description

[0015] FIG1 is a schematic diagram schematically showing an etching apparatus according to one embodiment of the present invention. Implementation Method

[0016] 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 the common knowledge of the industry within the scope of not impairing the gist of the present invention.

[0017] <Etching method> 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], an isocyanate sulfonyl 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. R 1-S(=O) 2-X [1] (In the general formula [1], R1 is a linear or branched alkyl group having 1 to 6 carbon atoms in which a part or all of the hydrogen atoms may be substituted by fluorine atoms, or a halogen atom. X is a halogen atom) R 2-C(=O)-R 3[2] (In the general formula [2], R2 and R3 are each independently a linear or branched alkyl group having 1 to 6 carbon atoms, in which a part or all of the hydrogen atoms may be substituted by 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], R4 is a linear or branched alkyl group having 1 to 6 carbon atoms, in which some or all of the hydrogen atoms may be substituted by fluorine atoms, or a halogen atom) R 5-N=C=O [4] (In the general formula [4], R 5 is a linear or branched alkyl group having 1 to 10 carbon atoms in which some or all of the hydrogen atoms may be substituted by fluorine atoms)

[0018] As a film containing at least Si and O, a silicon oxide (SiO 2 ) film can be mentioned. As a film containing at least Si and N, a silicon nitride (SiN) film can be cited.

[0019] As for the linear or branched alkyl group having 1 to 6 carbon atoms in which some or all of the hydrogen atoms of R1 in the general formula [1] may be substituted by fluorine atoms, examples thereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, n-pentyl, and n-hexyl. As for the halogen atom of R1 in the general formula [1], examples thereof include fluorine, chlorine, bromine, and iodine atoms. R1 is preferably a fluoroalkyl group or a fluorine atom. More preferably, R1 is a trifluoromethyl group or a fluorine atom. The halogen atom as X in the general formula [1] may be the same as that for R 1. X is preferably a fluorine atom.

[0020] 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), and sulfonyl chloride (SO2Cl2). The sulfonyl compound is preferably trifluoromethanesulfonyl fluoride (CF3S(=O)2F) or sulfonyl fluoride (SO2F2).

[0021] Regarding the linear or branched alkyl group having 1 to 6 carbon atoms, and the halogen atom, in which some or all of the hydrogen atoms of R2 and R3 in the general formula [2] may be substituted with fluorine atoms, the same as those exemplified for R1 in the general formula [1] may be mentioned. R2 and R3 are preferably alkyl groups, trifluoroalkyl groups, or hydrogen atoms, and more preferably methyl groups, trifluoromethyl groups, or hydrogen atoms. Also preferred are carbonyl compounds in which either R2 or R3 is a halogen atom and the other is an isocyanate group.

[0022] 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), and chlorocarbonyl isocyanate (ClC(=O)N=C=O). The carbonyl compound is preferably hexafluoroacetone (CF3C(=O)CF3), trifluoroacetaldehyde (CF3C(=O)H), or fluorocarbonyl isocyanate (FC(=O)N=C=O), and more preferably hexafluoroacetone (CF3C(=O)CF3) or trifluoroacetaldehyde (CF3C(=O)H). Acetaldehyde or trifluoroacetaldehyde may exist as stable equivalents, such as themselves, self-polymers, hydrates, hemiacetals, acetals, and compounds formed by combinations of these structural features. Therefore, in the present invention, these stable equivalents are also considered to be included in the carbonyl compounds represented by general formula [2].

[0023] As for the linear or branched alkyl group having 1 to 6 carbon atoms in which some or all of the hydrogen atoms of R4 in the general formula [3] may be substituted with fluorine atoms, and the halogen atom, the ones exemplified for R1 in the general formula [1] may be mentioned. R4 is preferably a halogen atom, more preferably a fluorine atom. 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. The sulfonyl isocyanate compound is preferably fluorosulfonyl isocyanate (FS(=O) 2N=C=O).

[0024] As for the linear or branched alkyl group having 1 to 10 carbon atoms in which some or all of the hydrogen atoms of R 5 in the general formula [4] may be substituted by fluorine atoms, examples thereof include those exemplified for R 1 in the general formula [1], as well as n-heptyl, n-octyl, n-nonyl, n-decyl, and the like. 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, t-butyl isocyanate, and the like. The isocyanate compound is preferably methyl isocyanate, ethyl isocyanate, or n-propyl isocyanate from the viewpoint of reactivity with a film containing Si and N.

[0025] The process temperature for contacting the film formed on the substrate with (I) HF gas is preferably 20°C to 200°C, more preferably 30°C to 150°C, and even more preferably 40°C to 130°C. The process temperature for contacting the film formed on the substrate with the compound (II) and the process temperature for simultaneously contacting the film formed on the substrate with both (I) HF gas and (II) compound are also preferably within the above temperature range. When the process temperature is within the above temperature range, reactivity with the film containing Si and N is improved, productivity is improved, and damage to the substrate is minimized.

[0026] The etching method of the present invention preferably etches the film containing Si and N without using a plasma state. This is because, if the substrate is a semiconductor device substrate, contact with plasma gas may cause electrical damage to the substrate.

[0027] The etching method of the present invention is suitable for selectively etching the aforementioned film containing Si and N. In the etching method of the present invention, it is preferred that the etching be performed selectively on the aforementioned film containing Si and N, and that the etching rate for the aforementioned film containing Si and O be performed at a rate of 1.0 nm / min or less. More preferably, the rate is 0.5 nm / min or less. The etching rate is calculated based on the contact time of the HF gas. 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 etching rate of the film containing Si and O (film containing Si and N / film containing Si and O) is 5 or greater. The etching rate ratio is preferably 10 or greater, more preferably 15 or greater, and particularly preferably 30 or greater.

[0028] 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 also be formed on the substrate surface. The etching method of the present invention is suitable for a silicon nitride film adjacent to a silicon oxide film, with the silicon oxide film and the silicon nitride film exposed. The etching method of the present invention is suitable for a silicon nitride film adjacent to a silicon oxide film and a polysilicon film, with the silicon oxide film, the polysilicon film, and the silicon nitride film exposed. The substrate is placed on a stage of an etching apparatus described below, for example, 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.

[0029] The method for forming a film on the substrate surface is not particularly limited, and examples thereof include chemical vapor deposition (CVD) and sputtering. Furthermore, the thickness of the film comprising Si and O and the film comprising Si and N is not particularly limited, and for example, can be set to a thickness of not less than 0.1 nm and not more than 1 μm.

[0030] The etching method of the present invention preferably performs the etching by placing the substrate in a chamber. The etching method of the present invention preferably includes the step of creating a reduced pressure in the chamber. The etching method of the present invention more preferably includes the step of bringing the HF gas (I) and the compound (II) into contact with a substrate having a film containing at least Si and O and a film containing at least Si and N in the chamber, and then creating a reduced pressure in the chamber. This is because byproducts generated during etching can be removed. The reduced pressure state refers to a pressure state in which the pressure in the chamber is lower than the pressure during etching (process pressure), which is generally below 0.133 kPa.

[0031] The etching method of the present invention preferably includes a step of replacing the chamber atmosphere with an inert gas. More preferably, the etching method of the present invention includes the step of replacing the chamber atmosphere with an inert gas after contacting the HF gas (I) and the compound (II). This is because byproducts generated during etching can be removed. The etching method of the present invention can perform a step of replacing the chamber with an inert gas after performing a step of providing a reduced pressure state in the chamber. For example, an oxide film or an oxynitride film is generally 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 such films can be performed before the above-mentioned (I) HF gas and the above-mentioned (II) compound are brought into contact with the substrate.

[0032] [First Etching Method] First, as an etching method of the present invention, a first etching method is described, in which the aforementioned (I) HF gas and the aforementioned (II) compound are simultaneously brought into contact with the aforementioned substrate. Hereinafter, the etching gas used in the first etching method is referred to as etching gas A. Etching gas A contains at least the aforementioned (I) HF gas and the aforementioned (II) compound.

[0033] 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. It is speculated that if the heated film to be etched is exposed to (I) HF gas and the compound (II) simultaneously, the compound (II) will directly bond with Si-NH2 on the surface of the film containing Si and N (especially the 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 in the etched film can be selectively etched.

[0034] Examples of the compound (II) include the same compounds as those mentioned above.

[0035] The volume ratio of HF gas (I) to compound (II) is preferably 10:0.01 to 10, more preferably 10:0.01 to 6. If the HF gas ratio is too low, the etching rate tends to decrease, while if it is too high, the cost is too high. Furthermore, even if the compound (II) is too high, etching is not likely to proceed. The compound (II) exhibits its effect even in a trace amount, so when the total of HF gas, the compound (II) and the following added gas is set to 100% by volume, the compound (II) may be 1 ppm by volume or more.

[0036] Etching gas A may consist solely of (I) HF gas and the compound (II), or may further include at least one additional gas selected from the group consisting of O₂, NO, N₂O, CO, CO₂, H₂O₂, and alcohols. It may further include at least one inert gas selected from the group consisting of N₂, Ar, He, Ne, and Kr. Alcohols that can be used include methanol, ethanol, propanol, and isopropanol.

[0037] When an additional gas is used, the total content of the additional gas can be set to 10% by volume or more and 90% by volume or less, when the total of (I) HF gas, (II) compound, the above-mentioned additional gas, and the above-mentioned inert gas is set to 100% by volume.

[0038] When the etching gas A contains an inert gas, the content of the inert gas contained in the etching gas A is preferably from 1 volume % to 90 volume %, more preferably from 10 volume % to 80 volume %, and even more preferably from 30 volume % to 50 volume %, when the total of (I) HF gas, (II) compound, the above-mentioned additive gas, and the above-mentioned inert gas is set to 100 volume %.

[0039] The water content in the etching gas A is preferably less than 1% by mass. This is because if the water content is high, H2O may be generated during vaporization, and the film containing Si and O (SiO2 film) may be etched due to HF+H2O.

[0040] The first etching method preferably includes the steps of simultaneously contacting the substrate with the HF gas (I) and the compound (II) in a chamber, and placing the chamber in a reduced pressure state, and performing these steps repeatedly to perform etching. The step of replacing the chamber with an inert gas may be performed instead of the step of placing the chamber in a reduced pressure state, or the step of replacing the chamber with an inert gas may be performed after the step of placing the chamber in a reduced pressure state. As one aspect, in the first etching method, it is preferred that the step of simultaneously contacting the substrate with the HF gas (I) and the compound (II) in a chamber be performed followed by the step of placing the chamber in a reduced pressure state and / or the step of replacing the chamber with an inert gas.

[0041] [Second Etching Method] Next, a second etching method will be described as an etching method of the present invention. This second etching method 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 will be referred to as etching gas B, and the etching gas used in the second etching step will be referred to as etching gas C. Etching gas B contains at least the HF gas (I), and etching gas C contains at least the compound (II).

[0042] It is believed that if 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, the compound (II) directly bonds with Si-NH₂ on the surface of the film containing Si and N (particularly the SiN film) without releasing protons (H⁺). Subsequently, as a first etching step, when the etching gas B containing the HF gas (I) is brought into contact with the film to be etched, NH₃ is not generated, and the film containing Si and N can be selectively etched. In the second etching method of the present invention, the above steps can be repeated multiple times to repeatedly etch the film to be etched. In one etching cycle, a certain thickness can be etched. Therefore, by specifying the number of cycles, a layer of the desired thickness can be precisely etched.

[0043] As the compound (II), the same compounds as those mentioned above can be used.

[0044] The etching gas B may consist solely of (I) HF gas, and the etching gas C may consist solely of the compound (II). Etching gas B and etching gas C may each further include at least one additive gas selected from the group consisting of O₂, NO, N₂O, CO, CO₂, H₂O₂, and alcohols. Etching gas B and etching gas C may each further include at least one inert gas selected from the group consisting of N₂, Ar, He, Ne, and Kr. Alcohols that can be used include methanol, ethanol, propanol, and isopropanol.

[0045] When the etching gas B contains an additive gas, the total content of the additive gas contained in the etching gas B can be set to be greater than 10 volume % and less than 90 volume % when the total of (I) HF gas, the above-mentioned additive gas, and the above-mentioned inert gas is set to 100 volume %. Furthermore, when the etching gas C contains an additive gas, the total content of the additive gas contained in the etching gas C can be set to be greater than 10 volume % and less than 90 volume % when the total of the compound (II), the above-mentioned additive gas, and the above-mentioned inert gas is set to 100 volume %.

[0046] When the etching gas B contains an inert gas, the content of the inert gas 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 %, when the total of (I) HF gas, the above-mentioned additional gas, and the above-mentioned inert gas is set to 100 volume %. When the etching gas C contains an inert gas, the content of the inert gas in the etching gas C is preferably 1% by volume to 90% by volume, more preferably 10% by volume to 80% by volume, and even more preferably 30% by volume to 50% by volume, when the total of the compound (II), the above-mentioned additional gas, and the above-mentioned inert gas is set to 100% by volume.

[0047] The water content in etching gas B and etching gas C is preferably less than 1% by mass. This is because if the water content is high, H₂O may be generated during vaporization, and the HF+H₂O reaction may cause etching of the film containing Si and O (SiO₂ film).

[0048] The second etching method preferably includes the following steps: performing a first etching step and a second etching step in a chamber, and then applying a reduced pressure to the chamber. Etching is preferably performed by repeating these steps. Instead of applying a reduced pressure to the chamber, a step of replacing the chamber with an inert gas may be performed, or the step of replacing the chamber with an inert gas may be performed after applying a reduced pressure to the chamber. In one embodiment, in the second etching method, the step of applying a reduced pressure to the chamber and / or the step of replacing the chamber with an inert gas are preferably performed after the second etching step, and then, after the first etching step, the step of applying a reduced pressure to the chamber and / or the step of replacing the chamber with an inert gas are performed.

[0049] Furthermore, one of the present inventions is an etching method for etching a substrate having a polysilicon film and a film containing at least Si and N, by bringing the substrate into contact with (I) HF gas and (II) at least one compound selected from the group consisting of a sulfonyl compound represented by the above-mentioned general formula [1], a carbonyl compound represented by the above-mentioned general formula [2], an isocyanate sulfonyl compound represented by the above-mentioned general formula [3], and an isocyanate compound represented by the above-mentioned general formula [4], and etching the above-mentioned film containing Si and N.

[0050] On the surface of the above-mentioned substrate, 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 metal nitride, a silicon film, a metal wiring film, etc. can also be formed.

[0051] Regarding the compound (II) in contact with the substrate and the etching conditions, the same compounds and conditions as those used in the etching method for the substrate having a film containing at least Si and O and a film containing at least Si and N can be used.

[0052] [Etching equipment] The etching method of the present invention can be implemented, for example, by using the following etching apparatus. This etching apparatus is also one of the present inventions. 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], an isocyanate sulfonyl 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.

[0053] FIG1 is a schematic diagram schematically showing an etching apparatus according to one embodiment of the present invention. The etching apparatus 100 shown in FIG1 includes: a chamber 110 in which a substrate 113 is disposed; 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 mechanism 111 to heat the chamber 110. Furthermore, the etching apparatus 100 may not include the inert gas supply unit 130.

[0054] The etching apparatus 100 further includes a control unit (not shown). This control unit comprises, for example, a computer equipped with a program, memory, and a CPU (central processing unit). The program includes a group of steps for implementing a series of actions in either 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 rates of each gas are adjusted, and the pressure within the chamber 110 is adjusted. The program is stored in a computer storage medium, such as an optical disc, hard drive, magneto-optical disc, or memory card, and is installed in the control unit.

[0055] The chamber 110 includes a stage 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 depressurized to a predetermined pressure. A typical chamber such as that used in semiconductor etching equipment can be used. Furthermore, the supply pipe or other piping for the etching gas is not particularly limited, and any typical supply pipe or piping can be used as long as it is resistant to the HF gas.

[0056] The HF gas supply unit 140 adjusts the supply amount by means of valves 143 and 144 and a flow rate adjustment mechanism 142 , and supplies HF gas from pipes 141 and 145 to the pipe 121 .

[0057] The gaseous compound (II) supply unit 150 adjusts the supply amount by means of valves 153 and 154 and a flow rate adjustment mechanism 152 , and supplies the gaseous compound (II) from pipes 151 and 155 to the pipe 121 .

[0058] The inert gas supply unit 130 adjusts the supply amount by means of valves 133 and 134 and a flow rate adjustment mechanism 132 , and supplies the inert gas from pipes 131 and 135 to the pipe 121 .

[0059] A heating mechanism 111 is provided outside the chamber 110 to heat the chamber 110. Furthermore, a heater (not shown) may be provided inside the mounting table 112 as a second heating mechanism. Furthermore, when multiple mounting tables are arranged in the chamber 110, each mounting table can be equipped with a heater, allowing the temperature of the substrate on each mounting table to be set to a predetermined temperature.

[0060] A gas exhaust mechanism for exhausting post-reaction gases is installed at one end of chamber 110. The post-reaction gases are exhausted from chamber 110 via pipe 122 using a vacuum pump 127 in the gas exhaust mechanism. A liquid nitrogen cold trap (not shown) can be installed between pipe 122 and vacuum pump 127 to recover the post-reaction gases. Valves 125 and 126 can be installed in pipes 121 and 122 to adjust the pressure. In Figure 1, PIs 123 and 124 are pressure gauges. Based on their indicated values, the control unit controls the flow control mechanisms and valves.

[0061] Taking the etching device 100 as an example, the etching method is described in detail. [First Etching Method Using the Etching Apparatus] In the first etching method of the present invention, etching gas A containing (I) HF gas and (II) compound is brought into contact with the film to be etched.

[0062] In the first etching method, a substrate 113 having a film to be etched formed thereon, the film to be etched comprising at least Si and O and at least Si and N, is first placed in a chamber 110. Next, a vacuum pump 127 evacuates the interior of the chamber 110, along with pipes 121 and 122, pipes 131 and 135, pipes 141 and 145, and pipes 151 and 155, until a predetermined pressure is reached. The substrate 113 is then heated by a heating mechanism 111. When the substrate 113 reaches a predetermined temperature, HF gas and compound (II) gas are supplied to the pipe 121 at predetermined flow rates from the HF gas supply unit 140 and compound (II) gas supply unit 150. Furthermore, an inert gas can be supplied to the pipe 121 at predetermined flow rates from the inert gas supply unit 130.

[0063] HF gas and gas compound (II) are mixed in a predetermined composition and supplied to chamber 110. While the mixed etching gas is introduced into chamber 110, the pressure within chamber 110 is controlled to a predetermined value. Etching is performed by allowing etching gas A to react with the film to be etched for a predetermined period of time. This etching method allows etching to be performed in a plasma-free state, eliminating the need for plasma or other means to excite etching gas A. The flow rate of etching gas A can be appropriately set based on the chamber volume and pressure.

[0064] Furthermore, etching in a plasma state refers to introducing a gas of, for example, 0.01 to 1.33 kPa into the interior of a reaction device, applying high-frequency power to an outer coil or a counter electrode, thereby generating a low-temperature gas plasma in the reaction device, and etching is performed by active chemical species such as ions or free radicals generated therein. In the etching method of the present invention, the gas is contacted without plasma state, and dry etching is performed without generating the above-mentioned gas plasma.

[0065] After the etching step is completed, heating by the heating mechanism 111 is stopped and the temperature is lowered. The vacuum pump 127 is stopped and the vacuum is replaced with an inert gas to release the vacuum. As described above, by using the first etching method of the etching apparatus, the film containing Si and N in the etched film can be selectively etched.

[0066] (Etching Conditions in the First Etching Method) In the first etching method of the present invention, when the etching gas A is brought into contact with the above-mentioned etched film, the temperature of the 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 even more preferably above 40°C and below 130°C.

[0067] Furthermore, 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, and is generally within a pressure range of 0.01 kPa to 101.3 kPa.

[0068] From the perspective 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 even more preferably 1 kPa to 20 kPa.

[0069] The processing time of the etching step is not particularly limited; however, considering the efficiency of the semiconductor device manufacturing process, it is preferably within 60 minutes. Here, the processing time of the etching step refers to the time from the introduction of etching gas A into the chamber containing the substrate to the completion of the etching process by exhausting the etching gas A from the chamber using a vacuum pump or the like.

[0070] [Second Etching Method Using the Etching Apparatus] The second etching method of the present invention comprises: 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 a compound of (II) into contact with the film to be etched.

[0071] In the second etching method, substrate 113, on which a film containing at least Si and O and a film containing at least Si and N are formed, is first placed in chamber 110. Next, chamber 110, pipes 121 and 122, pipes 131 and 135, pipes 141 and 145, and pipes 151 and 155 are evacuated by vacuum pump 127 until a predetermined pressure is reached. Then, substrate 113 is heated by heating mechanism 111.

[0072] After the substrate 113 reaches a predetermined temperature, the gaseous compound (II) is first supplied from the gaseous compound (II) supply unit 150 to the pipe 121 at a predetermined flow rate. Furthermore, an inert gas can be supplied from the inert gas supply unit 130 to the pipe 121 at a predetermined flow rate. While the gaseous compound (II) or the gaseous compound (II) and the inert gas are introduced into the chamber 110, the pressure within the chamber 110 is controlled to a predetermined value. By introducing the gaseous compound (II) into the chamber 110 for a predetermined period of time, the gaseous compound (II) is adsorbed onto the film to be etched. After the gas containing the gaseous compound (II) is evacuated, HF gas is supplied from the HF gas supply unit 140 to the pipe 121 at a predetermined flow rate. Furthermore, an inert gas can be supplied from the inert gas supply unit 130 to the pipe 121 at a predetermined flow rate. While introducing HF gas, or HF gas and inert gas, into the chamber 110, the pressure within the chamber 110 is controlled to a predetermined value. By introducing HF gas into the chamber 110 for a predetermined period of time, the film containing Si and N among the aforementioned etched films can be selectively etched.

[0073] In the second etching method of the present invention, the following steps may be repeated for a plurality of cycles, wherein a first etching step of introducing HF gas into the chamber 110 and a second etching step of introducing the gaseous compound (II) into the chamber 110 constitute one cycle. In the second etching method of the present invention, by setting the etching conditions of one cycle to prescribed 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. In the second etching method of the present invention, it is preferred that after the second etching step, a step of applying a reduced pressure to the chamber is performed, followed by the first etching step. Furthermore, it is preferred that the step of applying a reduced pressure to the chamber is performed for each cycle.

[0074] Furthermore, the second etching method can also be performed in a plasma-free state, without the plasma state. During etching, there is no need to excite the etching gas using plasma or the like. The flow rates of the HF gas and the gaseous compound (II) can be appropriately set based on the volume and pressure of the chamber.

[0075] Thus, 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.

[0076] After the etching step is completed, heating by the heating mechanism 111 is stopped and the temperature is lowered. The vacuum pump 127 is stopped and the vacuum is replaced with an inert gas to release the vacuum. By using the second etching method of the etching apparatus described above, the film containing Si and N in the etched film can be selectively etched.

[0077] (Etching Conditions in the Second Etching Method) In the second etching method of the present invention, during the etching step, the temperature of the film to be etched can be any temperature at which etching gas B reacts with the film containing Si and N (SiN film), and etching gas C reacts with the film containing Si and N (SiN film). In particular, the temperature of the film to be removed is preferably from 20°C to 200°C, more preferably from 30°C to 150°C, and even more preferably from 40°C to 130°C. The temperature of the film to be etched in the first and second etching steps is preferably the same.

[0078] Furthermore, the pressure in the chamber during the etching step is not particularly limited, and is generally within a pressure range of 0.01 kPa to 101.3 kPa.

[0079] From the perspective of achieving a sufficient etching rate, the pressure within the chamber during the first and second etching steps is preferably 0.01 kPa to 101.3 kPa, more preferably 0.1 kPa to 50 kPa, and even more preferably 1 kPa to 20 kPa. The pressure within the chamber during the second etching step is preferably higher than the pressure within the chamber during the first etching step.

[0080] The processing time in the first and second etching steps is not particularly limited. The processing time for one cycle of the first etching step is preferably within 60 minutes, and the processing time for one cycle of the second etching step is preferably within 60 minutes. The processing time in the etching step refers to the time from the introduction of etching gas into the chamber containing the substrate to the completion of the etching process by exhausting the etching gas from the chamber using a vacuum pump or the like.

[0081] [Method for manufacturing semiconductor device] The etching method of the present invention can be used to selectively etch 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 inexpensively. The semiconductor device manufacturing method of the present invention is characterized by comprising the step of applying the aforementioned etching method to a substrate having a silicon nitride film and a silicon oxide film to selectively etch the silicon nitride film. The step of selectively etching the silicon nitride film without plasma by reacting the substrate having the silicon nitride film and the silicon oxide film with HF gas and the compound (II) can be performed using the aforementioned etching method of the present invention. The substrate may further have a polysilicon film. The substrate is preferably a silicon substrate.

[0082] [Etching gas] 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], an isocyanate sulfonyl compound represented by the general formula [3], and an isocyanate compound represented by the general formula [4] is also one of the present inventions. The etching gas of the present invention may be the same as the etching gas A described above. That is, the etching gas system of the present invention comprises at least a mixture of the above-mentioned (I) HF gas and the above-mentioned compound (II). [Example]

[0083] Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to these examples. First, as the substrates 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 were prepared. The film thickness of each substrate before and after etching was measured using a spectroscopic ellipsometer (SE-2000, manufactured by Semilab Japan KK). The etching amount and the selectivity of SiN to SiO2 and p-Si (SiN / SiO2 selectivity and SiN / p-Si selectivity) were calculated.

[0084] [Example 1] The etching apparatus 100 shown in Figure 1 was used. First, the substrate to be processed was placed on a stage within the chamber. After the chamber was fully evacuated, the stage temperature was set to 120°C. The substrate temperature was the same as the stage temperature, essentially equal to the temperature of the film to be etched. Next, N₂ gas was flowed through the chamber to thoroughly dry the substrate. Thereafter, HF gas and CF₃S(=O)₂F (trifluoromethanesulfonyl fluoride) gas were flowed through the chamber for 1 minute. The gas flow rates at this time were set to 200 sccm for HF gas and 100 sccm for CF₃S(=O)₂F gas, and the chamber pressure was set to 6.66 kPa. Finally, the chamber was evacuated, replaced with N₂ gas, and the substrate to be processed was removed. The results are shown in Table 1. A silicon wafer with a SiN film formed on it, a silicon wafer with a SiO2 film formed on it, and a silicon wafer with a polysilicon (p-Si) film formed on it, which are substrates to be processed, are all placed in the same chamber and etched simultaneously.

[0085] [Example 2] The experiment was conducted under the same conditions as in Example 1, except that HF ​​gas and CF3C(=O)CF3 (hexafluoroacetone) gas were circulated for 15 minutes instead of HF gas and CF3S(=O)2F gas. The results are shown in Table 1.

[0086] [Example 3] The experiment was conducted under the same conditions as in Example 1, except that HF ​​gas and FS(=O)2N=C=O (fluorosulfonyl isocyanate) gas were circulated for 15 minutes instead of HF gas and CF3S(=O)2F gas. The results are shown in Table 1.

[0087] [Example 4] The experiment was conducted under the same conditions as in Example 1, except that HF ​​gas and S(=O)2F2 (sulfonyl fluoride) gas were circulated for 15 minutes instead of HF gas and CF3S(=O)2F gas. The results are shown in Table 1.

[0088] [Comparative Example 1] The experiment was conducted under the same conditions as in Example 1, except that HF ​​gas and N2 gas were circulated for 10 minutes instead of HF gas and CF3S(=O)2F gas. The results are shown in Table 1.

[0089] [Example 5] First, a substrate to be processed is placed on a mounting table in a chamber, the chamber is fully evacuated, and the mounting table temperature is set to 120° C. Next, N 2 gas is flowed through the chamber to fully dry the substrate. (A) After flowing CF₃S(=O)₂F gas into the chamber, the chamber was thoroughly evacuated and replaced with N₂ gas. The gas flow rate was set to 100 sccm for CF₃S(=O)₂F gas, the pressure was set to 6.66 kPa, and the CF₃S(=O)₂F gas flow time was set to 2 minutes. (B) Next, HF gas was flowed into the chamber, diluted with N₂ gas, and then fully evacuated and replaced with N₂ gas. The gas flow rates were set to 200 sccm for HF gas and 100 sccm for N₂ gas, the pressure was set to 6.66 kPa, and the HF / N₂ flow time was set to 1 minute. Here, cyclic etching was performed by repeating (A) and (B) 10 times. Finally, the processed substrate was removed from the chamber. The results are shown in Table 2. The etching rate was calculated based on the HF gas / N2 gas flow time.

[0090] [Example 6] The test was conducted under the same conditions as in Example 1, except that the pressure in the chamber was set to 5.33 kPa and HF gas and CF3S(=O)2F gas were circulated for 3 minutes. The results are shown in Table 3.

[0091] [Example 7] The test was conducted under the same conditions as in Example 1 except that the stage temperature was set to 50°C and HF gas and CF3S(=O)2F gas were circulated for 3 minutes. The results are shown in Table 3.

[0092] [Example 8] 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 flowing. The results are shown in Table 3.

[0093] [Example 9] 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 flowing. The results are shown in Table 3.

[0094] [Example 10] The test was conducted under the same conditions as in Example 1 except that the stage temperature was set to 30°C and HF gas and CF3S(=O)2F gas were circulated for 3 minutes. The results are shown in Table 3.

[0095] [Example 11] 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 flowing. The results are shown in Table 3.

[0096] [Example 12] 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 CF 3 S(═O) 2F gas were flowing. The results are shown in Table 3.

[0097] [Comparative Example 2] 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.

[0098] [Comparative Example 3] 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.

[0099] [Table 1] Process pressure [kPa] Process temperature [℃] HF gas flow rate [sccm] Gaseous compounds (II) Gas compound (II) flow rate [sccm] Add to gas Add gas flow [sccm] Time [min] SiN etching rate [nm / min] SiO2 etching rate [nm / min] SiN / SiO2 selectivity p-Si etching rate [nm / min] SiN / p-Si selectivity Example 1 6.66 120 200 CF 3S(=O) 2F 100 - - 1 2.2 0.0 ∞ 0.0 ∞ Example 2 6.66 120 200 CF 3C(=O)CF 3 100 - - 15 3.6 0.1 36 0.0 ∞ Example 3 6.66 120 200 FS(=O) 2N=C=O 100 - - 15 0.8 0.0 ∞ 0.0 ∞ Example 4 6.66 120 200 S(=O) 2F 2 100 - - 15 3.6 0.2 18 0.0 ∞ Comparative Example 1 6.66 120 200 - - N 2 100 10 3.5 1.8 1.9 0.0 ∞

[0100] [Table 2] Process pressure [kPa] Process temperature [℃] Gas circulation (A) Gas circulation (B) SiN etching rate [nm / min] SiO2 etching rate [nm / min] SiN / SiO2 selectivity p-Si etching rate [nm / min] SiN / p-Si selectivity Gaseous compounds (II) Gas compound (II) flow rate [sccm] HF gas flow rate [sccm] Add gas Add gas flow [sccm] Example 5 6.66 120 CF 3S(=O) 2F 100 200 N 2 100 5.5 0.0 ∞ 0.0 ∞

[0101] [Table 3] Process pressure [kPa] Process temperature [℃] HF gas flow rate [sccm] Gaseous compounds (II) Gas compound (II) flow rate [sccm] Add gas Add gas [sccm] time [min] SiN etching rate [nm / min] SiO2 etching rate [nm / min] SiN / SiO2 selectivity p-Si etching rate [nm / min] SiN / p-Si selectivity Example 6 5.33 120 200 CF 3S(=O) 2F 100 - - 3 4.7 0.1 47 0.0 ∞ Example 7 6.66 50 200 CF 3S(=O) 2F 100 - - 3 7.3 0.1 73 0.0 ∞ Example 8 4.00 50 200 CF 3S(=O) 2F 100 - - 3 3.7 0.0 ∞ 0.0 ∞ Example 9 2.00 50 200 CF 3S(=O) 2F 100 - - 3 1.8 0.0 ∞ 0.0 ∞ Example 10 6.66 30 200 CF 3S(=O) 2F 100 - - 3 3.2 0.1 32 0.0 ∞ Example 11 4.00 30 200 CF 3S(=O) 2F 100 - - 3 1.9 0.0 ∞ 0.0 ∞ Example 12 2.00 30 200 CF 3S(=O) 2F 100 - - 3 0.8 0.0 ∞ 0.0 ∞ Comparative Example 2 13.33 120 200 - - N 2 100 30 1.9 2.8 0.7 0.0 ∞ Comparative Example 3 4.00 120 200 - - N 2 100 30 1.9 3.1 0.6 0.0 ∞

[0102] Table 1 shows the gas flow conditions for Examples 1-4 and Comparative Example 1, as well as the results of the etching rate, SiN / SiO2 selectivity, and SiN / p-Si selectivity of the substrate being processed. Table 2 shows the gas flow conditions for Example 5, as well as the results of the etching rate, SiN / SiO2 selectivity, and SiN / p-Si selectivity of the substrate being processed. Table 3 shows the gas flow conditions for Examples 6-12 and Comparative Examples 2-3, as well as the results of the etching rate, SiN / SiO2 selectivity, and SiN / p-Si selectivity of the substrate being processed. Regarding the etching rate of the SiO 2 film, Examples 1 to 12 were 0.0 to 0.2 nm, whereas Comparative Examples 1 to 3 were ≧1.0 nm. In Examples 1 to 12, the etching of the SiO 2 film was suppressed. Regarding the SiN / SiO 2 selectivity, Examples 1, 3, 5, 8~9 and 11~12 are ∞, Example 2 is 36, Example 4 is 18, Example 6 is 47, Example 7 is 73, and Example 10 is 32. 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 / SiO 2 selectivity was 1.9, but the SiO 2 surface was etched. According to the results of Examples 1 to 12 above, it can be seen that by circulating HF gas and CF 3 S (= O) 2F gas and other compounds (II), it is possible to suppress the etching of SiO 2 or p-Si while etching SiN.

[0103] 100: Etching device 110: Chamber 111: Heating mechanism 112: loading platform 113:Substrate 121:Piping 122:Piping 123:PI (pressure gauge) 124:PI (pressure gauge) 125: Valve 126: Valve 127: Vacuum pump 130: Inert gas supply unit 131:Piping 132: Flow adjustment mechanism 133: Valve 134: Valve 135:Piping 140: HF gas supply unit 141:Piping 142: Flow adjustment mechanism 143: Valve 144: Valve 145:Piping 150: Gaseous compound (II) supply unit 151:Piping 152: Flow adjustment mechanism 153: Valve 154: Valve 155:Piping

Claims

1. An etching method for etching a substrate having at least a film containing Si and O and at least a film containing Si and N, by contacting it 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], wherein R1-S(=O)2-X [1] (in general formula [1], R1 is a straight-chain or branched alkyl or halogen atom having 1 to 6 carbon atoms in which some or all hydrogen atoms can be replaced by fluorine atoms, and X is a halogen atom) R2-C(=O)-R3 [2] (in general formula [2], R2 and R 3 are independently alkyl groups, hydrogen atoms, halogen atoms, or isocyanates of 1 to 6 carbons that can be partially or completely replaced by fluorine atoms. R4-S(=O) 2N=C=O [3] (In general formula [3], R4 is an alkyl group, hydrogen atom, halogen atom, or halogen atom of 1 to 6 carbons that can be partially or completely replaced by fluorine atoms.) R5-N=C=O [4] (In general formula [4], R5 is an alkyl group, hydrogen atom, 1 to 10 carbons that can be partially or completely replaced by fluorine atoms.) 2. The etching method of claim 1, wherein the above-mentioned film containing Si and N is etched without plasma.

3. The etching method of claim 1, which selectively etches the above-mentioned film containing Si and N.

4. The etching method of claim 1, wherein the etching is selectively performed 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.

5. The etching method of claim 1, wherein R1 in the above general formula [1] is a fluoroalkyl group or a fluorine atom, and X is a fluorine atom.

6. The etching method of claim 1, wherein the sulfonyl compound represented by the above general formula [1] is trifluoromethanesulfonyl fluoride (CF 3S(=O) 2F) or sulfonyl fluoride (SO 2F 2).

7. The etching method of claim 1, wherein the carbonyl compound represented by the above general formula [2] is hexafluoroacetone (CF 3C(=O)CF 3), trifluoroacetaldehyde (CF 3C(=O)H), or fluorocarbonyl isocyanate (FC(=O)N=C=O).

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

9. The etching method of claim 1, wherein the etching is performed by placing the substrate in a cavity, including the step of applying a depressurization state to the cavity.

10. The etching method of claim 1, wherein the HF gas (I) and the compound (II) are simultaneously contacted with the substrate.

11. The etching method of claim 1, comprising a first etching step of contacting the substrate with the HF gas described in (I) and a second etching step of contacting the substrate with the compound described in (II).

12. The etching method of claim 11, wherein etching is performed by repeatedly performing the first etching step and the second etching step described above.

13. The etching method of claim 11, wherein the first etching step is performed after the second etching step described above.

14. The etching method of claim 1, wherein the above-mentioned silicon oxide (SiO2) film containing Si and O.

15. The etching method of claim 1, wherein the above-mentioned silicon nitride (SiN) film comprising Si and N.

16. The etching method of claim 1, wherein in the substrate, the silicon oxide (SiO2) film containing Si and O, the silicon nitride (SiN) film containing Si and N, the silicon nitride film and the silicon oxide film are adjacent, and the silicon oxide film and the silicon nitride film are exposed.

17. A method for manufacturing a semiconductor device, comprising the step of selectively etching the silicon nitride film by applying an etching method as described in any one of claims 1 to 15 to a substrate having a silicon nitride film and a silicon oxide film.

18. An etching apparatus comprising: a stage for holding a substrate; an HF gas supply unit for supplying (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 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]; R1-S(=O)2-X [1] (in general formula [1], R1 is a straight-chain or branched alkyl or halogen atom with 1 to 6 carbon atoms in which some or all hydrogen atoms can be replaced by fluorine atoms, and X is a halogen atom) R2-C(=O)-R3 [2] (in general formula [2], R2 and R 3 are independently alkyl groups, hydrogen atoms, halogen atoms, or isocyanates of 1 to 6 carbons that can be partially or completely replaced by fluorine atoms. R4-S(=O) 2N=C=O [3] (In general formula [3], R4 is an alkyl group, hydrogen atom, halogen atom, or halogen atom of 1 to 6 carbons that can be partially or completely replaced by fluorine atoms.) R5-N=C=O [4] (In general formula [4], R5 is an alkyl group, hydrogen atom, 1 to 10 carbons that can be partially or completely replaced by fluorine atoms.) 19. An etching gas comprising: (I) HF gas; and (II) at least one compound selected from the group consisting of sulfonyl compounds represented by general formula [1], carbonyl compounds represented by general formula [2], sulfonyl isocyanate compounds represented by general formula [3], and isocyanate compounds represented by general formula [4]; R1-S(=O)2-X [1] (in general formula [1], R1 is a straight-chain or branched alkyl group of carbon 1 to 6 in which some or all hydrogen atoms can be replaced by fluorine atoms, or a halogen atom, and X is a halogen atom) R2-C(=O)-R3 [2] (in general formula [2], R2 and R3 are each independently a straight-chain or branched alkyl group of carbon 1 to 6 in which some or all hydrogen atoms can be replaced by fluorine atoms, a hydrogen atom, a halogen atom, or an isocyanate group) R4-S(=O)2N=C=O [3] (In general formula [3], R 4 is a straight-chain or branched alkyl or halogen atom with 1 to 6 carbons in which some or all hydrogen atoms can be replaced by fluorine atoms) R 5-N=C=O [4] (In general formula [4], R 5 is a straight-chain or branched alkyl with 1 to 10 carbons in which some or all hydrogen atoms can be replaced by fluorine atoms).

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