Silicon nitride film etching solution and its manufacturing method

Abstract

To provide a silicon nitride film etching solution capable of improving a selection ratio relative to a silicone oxide film.SOLUTION: The silicon nitride film etching solution includes a phosphoric acid aqueous solution and a compound represented by the formula in the figure, where X1 to X3 are selected from C1-C20 alkoxy, a hydroxy group and halogen; and R1 to R3 are selected from hydrogen, C1-C20 alkyl group, a C6-C12 cycloalkyl, C2-C10 heteroalkyl including at least one heteroatom, C2-C10 alkenyl, C2-C10 alkynyl, C1-C10 haloalkyl, C1-C10 aminoalkyl, aryl, heteroaryl, aralkyl and halogen.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a silicon nitride film etching solution and a manufacturing method thereof, and more particularly to a silicon nitride film etching solution capable of improving the etching selectivity ratio of a silicon nitride film to a silicon oxide film when etching a silicon nitride film, and a manufacturing method thereof. [Background technology]

[0002] Currently, there are various methods for etching silicon nitride films and silicon oxide films, and the dry etching method and the wet etching method are the most commonly used methods.

[0003] Dry etching is an etching method that generally uses a gas and has the advantage of being more isotropic than wet etching. However, it is less productive than wet etching and is expensive, so wet etching is becoming more widely used.

[0004] Generally, a method using phosphoric acid as an etching solution is well known as a wet etching method. In this case, if only pure phosphoric acid is used to etch a silicon nitride film, as devices become finer, not only the silicon nitride film but also the silicon oxide film may be etched, which may cause various defects and abnormal patterns. Therefore, it is necessary to form a protective film on the silicon oxide film to further reduce the etching rate of the silicon oxide film. Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a silicon nitride film etching solution capable of lowering the etching rate for a silicon oxide film and improving the etching selectivity ratio of a silicon nitride film to a silicon oxide film.

[0006] Another object of the present invention is to provide a silicon nitride film etching solution which maintains a stable etching rate in an etching process carried out at high temperatures and does not decrease the etching selectivity of a silicon nitride film to a silicon oxide film.

[0007] Another object of the present invention is to provide a method for producing the above-mentioned silicon nitride film etching solution. [Means for solving the problem]

[0008] In order to solve the above-mentioned technical problems, according to one aspect of the present invention, a silicon nitride film etching solution contains an aqueous phosphoric acid solution and a compound represented by the following Chemical Formula 1.

[0009] [C1] TIFF0007623111000001.tif42134

[0010] In the above formula 1, X1 to X3 are each independently C1-C 20 R1 to R3 are each independently selected from hydrogen, C1-C 20 Alkyl groups, C6-C 12 Cycloalkyl, C2-C containing at least one heteroatom 10 Heteroalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C1-C 10 Haloalkyl, C1-C 10 It is selected from aminoalkyl, aryl, heteroaryl, aralkyl, and halogen.

[0011] According to another aspect of the present invention, there is provided a method for producing a silicon nitride film etching solution, the method including: (a) mixing a silicon compound precursor with water to prepare a mixed solution, and then adding a hydroxide to the mixed solution to synthesize a silicon compound; (b) extracting the aqueous solution of the silicon compound synthesized in the step (a) from a first organic solvent, and then removing the first organic solvent; (c) mixing a result of the step (b) with a second organic solvent and refluxing the mixture; (d) lowering the temperature of the result of the step (c) to a range of 30°C to -40°C, and separating the crystallized solid compound; and (e) mixing the solid compound of the step (d) with an aqueous phosphoric acid solution to prepare a mixed solution. Effect of the Invention

[0012] Among the silicon nitride film etching solutions according to the present invention, the compound represented by Chemical formula 1 increases the bond with the silicon oxide film under etching conditions, thereby decreasing the etching rate of the silicon nitride film relative to the silicon oxide film.

[0013] At this time, the reactivity of the compound represented by Chemical Formula 1 used in the present application with the silicon oxide film and the hydroxyl group (-OH) is increased, so that an excellent passivation layer for the silicon oxide film can be formed. It can act as a layer. [Brief description of the drawings]

[0014] [Figure 1] 1A to 1C are cross-sectional views each showing a silicon nitride film removal process using an etching solution according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The advantages and features of the present invention, as well as the methods for achieving them, will become clear with reference to the following examples. However, the present invention is not limited to the examples disclosed below, and may be embodied in various different forms. However, the examples are provided to fully disclose the present invention and to fully inform those skilled in the art of the present invention of the scope of the invention, and the present invention is only defined by the scope of the claims.

[0016] The silicon nitride film etching solution and the manufacturing method thereof according to the present invention will be described in detail below.

[0017] <Silicon nitride film etching solution> According to one aspect of the present invention, there is provided a silicon nitride film etching solution comprising an aqueous phosphoric acid solution and a compound represented by Chemical Formula 1 below.

[0018] [C1] TIFF0007623111000002.tif42134

[0019] In the above formula 1, X1 to X3 are each independently C1-C 20 R1 to R3 are each independently selected from hydrogen, C1-C 20 Alkyl groups, C6-C 12 Cycloalkyl, C2-C containing at least one heteroatom 10 Heteroalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C1-C 10 Haloalkyl, C1-C 10 It is selected from aminoalkyl, aryl, heteroaryl, aralkyl, and halogen.

[0020] In addition, in the above formula 1, two of X1 to X3 are in a trans form in terms of stereochemical structure.

[0021] C in this application a -Cb The functional group means a functional group having a to b carbon atoms. For example, C a -C b Alkyl refers to a saturated aliphatic group having a to b carbon atoms, including straight chain alkyl and branched chain alkyl. A straight chain or branched chain alkyl has 10 or less carbon atoms (e.g., C1-C 10 Straight chain, C3-C 10 (branched chain), preferably having 4 or less, more preferably 3 or less carbon atoms.

[0022] Specifically, alkyl may be methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, i-butyl, t-butyl, pent-1-yl, pent-2-yl, pent-3-yl, 3-methylbut-1-yl, 3-methylbut-2-yl, 2-methylbut-2-yl, 2,2,2-trimethyleth-1-yl, n-hexyl, n-heptyl, and n-oxytyl.

[0023] By alkoxy herein is meant both an -O-(alkyl) group and an -O-(unsubstituted cycloalkyl) group which is a straight or branched chain hydrocarbon having one or more ether groups and 1 to 10 carbon atoms.

[0024] Specific examples include, but are not limited to, methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, tert-butoxy, sdc-butoxy, n-pentoxy, n-hexoxy, 1,2-dimethylbutoxy, cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, cyclohexyloxy, and the like.

[0025] In this application, unless otherwise specified, cycloalkyl or heterocycloalkyl will be understood to be cyclic structures of an alkyl or heteroalkyl, respectively.

[0026] Non-limiting examples of cycloalkyl include cyclopentyl, cyclohexyl, 1-cyclohexenyl, 3-cyclohexenyl, and cycloheptyl.

[0027] Non-limiting examples of cycloalkyls containing heteroatoms include 1-(1,2,5,6-tetrahydropyridyl), 1-piperidinyl, 2-piperidinyl, 3-piperidinyl, 4-morpholinyl, 3-morpholinyl, tetrahydrofuran-2-yl, tetrahydrofuran-3-yl, tetrahydrothien-2-yl, tetrahydrothien-3-yl, 1-piperazinyl, and 2-piperazinyl.

[0028] Furthermore, the cycloalkyl or cycloalkyl containing a heteroatom may have a form in which a cycloalkyl, cycloalkyl containing a heteroatom, aryl or heteroaryl is bonded thereto or linked thereto via a covalent bond.

[0029] In this application, unless otherwise defined, aryl refers to an unsaturated aromatic ring containing a single ring or multiple rings (preferably 1 to 4 rings) bonded or covalently linked to each other. Non-limiting examples of aryl include phenyl, biphenyl, o-terphenyl, m-terphenyl, p-terphenyl, 1-naptyl, 2-naptyl, 1-anthryl, 2-anthryl, 9-anthryl, 1-phenanthrenyl, 2-phenanthrenyl, 3-phenanthrenyl, 4-phenanthrenyl, 9-phenanthrenyl, 1-pyrenyl, 2-pyrenyl, and 4-pyrenyl.

[0030] By heteroaryl herein is meant a radical in which one or more carbon atoms within the aryl defined above have been replaced with a non-carbon atom such as nitrogen, oxygen or sulfur.

[0031] In the present application, aralkyl refers to a functional group in which an aryl is substituted on the carbon of an alkyl, and is represented by -(CH2) nA generic term for Ar. Examples of aralkyl include benzyl (-CH2C6H5) or penethyl (-CH2CH2C6H5).

[0032] In this application, halogen refers to fluoro (-F), chloro (-Cl), bromo (-Br) or iodo (-I), and haloalkyl refers to alkyl substituted with the above-mentioned halogens, e.g., halomethyl refers to methyl (-CH2X, -CHX2 or -CX3) in which at least one of the methyl hydrogens has been replaced with a halogen.

[0033] Generally, silicon compounds used as additives have the effect of protecting silicon oxide films from phosphoric acid solutions. However, silicon impurities generated after etching can combine with the silicon compounds to form particles that contaminate the silicon substrate.

[0034] Silane compounds in which hydrophilic functional groups are bonded to silicon atoms are easily decomposed at low temperatures by reaction with water and can form silicon-hydroxy groups (-Si-OH). Silicon-hydroxy groups are polymerized to form siloxane (-Si-O-Si-) groups that form random chain structures as silicon atoms and oxygen atoms are alternately bonded. Silane compounds containing siloxane groups are silicon-based particles formed by repeated polymerization of siloxane, which grow and precipitate, causing problems in terms of reduced storage safety.

[0035] The silicon nitride film etching solution according to an embodiment of the present invention contains a compound represented by the following Chemical Formula 1 in order to suppress generation of particles.

[0036] [C1] TIFF0007623111000003.tif42134

[0037] In the above formula 1, X1 to X3 are each independently C1-C 20R1 to R3 are each independently selected from hydrogen, C1-C 20 Alkyl groups, C6-C 12 Cycloalkyl, C2-C containing at least one heteroatom 10 Heteroalkyl, C2-C 10 Alkenyl, C2-C 10 Alkynyl, C1-C 10 Haloalkyl, C1-C 10 It is selected from aminoalkyl, aryl, heteroaryl, aralkyl, and halogen.

[0038] Here, the compound of the present invention represented by Chemical formula 1 exhibits a cyclic structure, which allows the compound structure to be maintained until the temperature reaches a high level. This reduces the phenomenon in which silicon-hydroxy groups are polymerized to form siloxane (-Si-O-Si-) compounds, thereby suppressing the generation of particles.

[0039] In addition, the silicon nitride film etching solution according to the embodiment of the present invention includes a compound represented by Chemical Formula 1 in order to increase the reactivity with a hydroxyl group (-OH) of a silicon oxide film and thereby increase the etching selectivity of a silicon nitride film to a silicon oxide film.

[0040] Specifically, the compound represented by Chemical formula 1 contained in the silicon nitride film etching solution forms a bimolecular SN2 (SN2) bond with the hydroxyl group (-OH) of the silicon oxide film. A passivation layer of the silicon oxide film is formed by the Nucleophilic Substitution reaction. In order to sufficiently form a hydroxyl layer, the SN2 reactivity between the compound and the hydroxyl group (-OH) must be increased. Specifically, the more unstable the compound structure is, the more the SN2 reactivity with the hydroxyl group (-OH) can be increased, and the reactivity between the compound and the hydroxyl group (-OH) may be determined according to the degree of stability of the compound structure.

[0041] The cyclic compounds used as additives in silicon nitride etching solutions can have a cis or trans stereochemical structure.

[0042] As an example, a cis-compound may react under etching conditions according to Reaction Scheme 1 below.

[0043] [Reaction Scheme 1] TIFF0007623111000004.tif68134

[0044] As shown in the above reaction formula 1, the cis-type compound may react with an aqueous phosphoric acid solution under etching conditions to add a cation to the hydroxyl group (-OH). By adding a cation, the hydroxyl group (-OH) becomes -OH2 + The hydroxyl groups (-OH) and -OH2 + An SN2 reaction may be carried out with

[0045] However, in cis compounds, the leaving group is -OH2 + The hydroxyl groups (-OH) of the nucleophile are not aligned axially. That is, every hydroxyl group (-OH) of the cis compound is aligned with the -OH2 of the leaving group. + In the cis-type compound, the hydroxyl groups (-OH) and -OH2 in the molecule are aligned horizontally (equatorially). + The SN2 reaction with

[0046] Here, the compound represented by Chemical formula 1 of the present invention has a hydroxy group (-OH) and a -OH2 + An SN2 reaction with may be carried out.

[0047] As an example, the compound represented by Chemical Formula 1 of the present invention may be represented by a compound represented by Chemical Formula 2 or 3 below.

[0048] [C2] TIFF0007623111000005.tif42134

[0049] [C3] TIFF0007623111000006.tif39134

[0050] In the above formula 2 and formula 3, R1 to R3 are each independently hydrogen, C1-C 20 Alkyl groups, C6-C 12 Cycloalkyl, C6-C 30 aryl, and halogen.

[0051] As an example, the trans compound represented by Chemical Formula 2 above may undergo a reaction according to Reaction Scheme 2 below under etching conditions.

[0052] [Reaction Scheme 2] TIFF0007623111000007.tif68134

[0053] As shown in the above reaction formula 2, the trans compound of the present invention, like the cis compound, may react with an aqueous phosphoric acid solution under etching conditions to add a cation to the hydroxy group (-OH).

[0054] However, unlike the cis-type compounds, the trans-type compounds of the present invention have a leaving group of -OH2 + The hydroxy group (-OH) of the nucleophile and the hydroxy group (-OH) of the nucleophile are arranged in the axial direction. As a result, the trans compound has a hydroxy group (-OH) and -OH2 + The SN2 reaction with this leads to the formation of an unstable Si-O-Si structure.

[0055] Here, the trans compound may have an unstable Si-O-Si structure in the molecule, which may increase the SN2 reactivity with the hydroxyl group (-OH) on the silicon oxide film surface.

[0056] Specifically, the compound containing the unstable Si—O—Si structure and the hydroxyl group (—OH) on the surface of the silicon oxide film may react according to the following reaction formula 3.

[0057] [Reaction Scheme 3] TIFF0007623111000008.tif45134

[0058] As shown in the above reaction formula 3, the compound containing the unstable Si-O-Si structure has a high bond angle strain. This increases the SN2 reactivity of the compound with the hydroxyl groups (-OH) on the silicon oxide film surface, allowing the compound to easily bond with the hydroxyl groups (-OH) on the silicon oxide film surface.

[0059] That is, the compound bonded to the hydroxyl group (-OH) on the surface of the silicon oxide film forms a passivation layer (passivation layer) of the silicon oxide film. By forming a second insulating layer (22) to reduce the etching rate of the silicon oxide film, the etching selectivity of the silicon oxide film to the silicon nitride film can be improved.

[0060] The additive containing the compound represented by Chemical Formula 1 is preferably present in the silicon nitride film etching solution at 50 to 200,000 ppm. Here, the content of the additive is the amount of the additive dissolved in the silicon nitride film etching solution, and is expressed in ppm units. For example, the presence of 5,000 ppm of the additive in the silicon nitride film etching solution may mean that the additive dissolved in the silicon nitride film etching solution is 5,000 ppm. If the additive is present in the silicon nitride film etching solution at less than 50 ppm, the amount of the additive is insufficient under the etching conditions, and the effect of increasing the etching selectivity of the silicon nitride film to the silicon oxide film may be weak. On the other hand, if the additive is present in the silicon nitride film etching solution at more than 200,000 ppm, a problem of a large amount of silicon-based particles being generated due to an increase in the saturation concentration of the additive in the silicon nitride film etching solution may occur.

[0061] In addition, the content of the trans compound represented by Chemical formula 1 in the additive is preferably 50% or more. More preferably, the content of the trans compound represented by Chemical formula 1 in the additive is preferably 90% or more. If the content of the additive represented by Chemical formula 1 is less than 50%, the reactivity with the hydroxyl group (-OH) on the surface of the silicon oxide film under etching conditions may be reduced. As a result, a protective layer for the silicon oxide film may not be formed sufficiently, and the effect of increasing the etching selectivity of the silicon oxide film to the silicon nitride film may be weak. That is, the higher the content ratio of the trans compound represented by Chemical formula 1 in the additive, the more the protective layer for the silicon oxide film may be formed sufficiently, and the more the etching selectivity of the silicon oxide film to the silicon nitride film may be improved.

[0062] The silicon substrate to be etched by the silicon nitride film etching solution according to the present invention is a silicon substrate having at least a silicon oxide film (SiO x ), or may include both a silicon oxide film and a silicon nitride film. In the case of a silicon substrate including both a silicon oxide film and a silicon nitride film, the silicon oxide film and the silicon nitride film may be laminated alternately or may be laminated in different regions.

[0063] Here, the silicon oxide film is classified into SOD (Spin On Dielectric) film, HDP (High Density Plasma film, thermal oxide film, BPSG (Borophosphate) film, thermal oxide film, BPSG (Borophosphate) film, Silicate Glass) membrane, PSG (Phospho Silicate Glass) membrane, BSG (Boro Silicate Glass) membrane Glass) membrane, PSZ (Polysilazane) membrane, FSG (Fluorinated Silicate) membrane Glass film, LP-TEOS (Low Pressure Tetra Ethyl Ortho Silicate) membrane, PETEOS (Plasma Enhanced Tetra Ethyl Ortho Silicate) membrane, HTO (High Temperature Oxide) membrane, MTO (Medium Temperature Oxide) film, USG (Undopped Silicate Glass) film, SOG (Spin On Glass) film, APL (Advanced Planarization) Layer film, ALD (Atomic Layer) Deposition) film, PE-oxide film (Plasma Enhanced oxide) or O3-TEOS (O3-Tetra Ethyl Ortho Silicate) etc.

[0064] Here, the phosphoric acid aqueous solution is a component that etches the silicon nitride film, maintains the pH of the etching solution, and suppresses the conversion of various forms of silicon compounds present in the etching solution into silicon-based particles.

[0065] In one embodiment, the phosphoric acid aqueous solution is preferably contained in an amount of 60 to 90 parts by weight per 100 parts by weight of the silicon substrate etching solution.

[0066] If the content of the phosphoric acid aqueous solution is less than 60 parts by weight per 100 parts by weight of the silicon substrate etching solution, the etching rate of the silicon nitride film may be reduced, so that the silicon nitride film may not be sufficiently etched or the efficiency of the silicon nitride film etching process may be reduced.

[0067] On the other hand, if the content of the phosphoric acid aqueous solution is more than 90 parts by weight per 100 parts by weight of the silicon nitride film etching solution, the increase in the etching rate of the silicon oxide film becomes larger than the increase in the etching rate of the silicon nitride film, so that the etching selectivity of the silicon oxide film to the silicon nitride film may decrease, and defects of the silicon substrate may be caused due to etching of the silicon oxide film.

[0068] The silicon nitride film etching solution according to an embodiment of the present invention may further include a fluorine-containing compound to compensate for the decrease in the etching rate of the silicon nitride film caused by the additive and to improve the efficiency of the overall etching process.

[0069] In this application, a fluorine-containing compound refers to any compound, in any form, that dissociates fluorine ions.

[0070] In one embodiment, the fluorine-containing compound is at least one selected from hydrogen fluoride, ammonium fluoride, ammonium bifluoride, and ammonium bifluoride.

[0071] In another embodiment, the fluorine-containing compound may be a compound in the form of an ionic bond between an organic cation and a fluorine-based anion.

[0072] For example, the fluorine-containing compound may be a compound in the form of an ionic bond between an alkyl ammonium and a fluorine-based anion. Here, the alkyl ammonium is an ammonium having at least one alkyl group, and may have up to four alkyl groups. The definition of the alkyl group is as described above.

[0073] In yet another example, the fluorine-containing compound may be an ionic liquid in the form of an ionic bond between an organic cation selected from alkylpyrroleum, alkylimidazolium, alkylpyrazolium, alkyloxazolium, alkylthiazolium, alkylpyridinium, alkylpyrimidinium, alkylpyridazinium, alkylpyrazinium, alkylpyrrolidinium, alkylphosphonium, alkylmorpholinium, and alkylpiperidinium, and a fluorine-based anion selected from fluorophosphate, fluoroalkyl-fluorophosphate, fluoroborate, and fluoroalkyl-fluoroborate.

[0074] Compared with hydrogen fluoride or ammonium fluoride, which are commonly used as fluorine-containing compounds in silicon nitride film etching solutions, the fluorine-containing compound provided in the form of an ionic liquid has a high boiling point and decomposition temperature, and is therefore advantageous in that it is unlikely to change the composition of the etching solution due to being decomposed during the etching process performed at high temperatures.

[0075] According to another aspect of the present invention, there is provided a method for manufacturing a semiconductor device using the silicon nitride film etching solution described above.

[0076] According to this manufacturing method, at least a silicon nitride film (SI x N y It is possible to manufacture a semiconductor device by performing a selective etching process for a silicon nitride film on a silicon substrate including the above-mentioned etching solution.

[0077] Silicon substrates used in the manufacture of semiconductor devices are coated with silicon nitride (SI x N y ) or may include both a silicon oxide film and a silicon nitride film. In the case of a silicon substrate including both a silicon oxide film and a silicon nitride film, the silicon oxide film and the silicon nitride film may be laminated alternately or may be laminated in different regions.

[0078] The method for manufacturing a semiconductor device according to the present invention may be applied to the manufacturing process of a NAND device. More specifically, the method can be performed by using the above-mentioned etching solution in a process step that requires selective removal of a silicon nitride film without loss of a silicon oxide film in a stacked structure for forming a NAND.

[0079] As an example, FIG. 1 is a schematic cross-sectional view illustrating a process for removing a silicon nitride film using an etching solution according to the present invention.

[0080] Referring to FIG. 1, a mask pattern layer 30 is formed on a laminated structure 20 in which silicon nitride films 11 and silicon oxide films 12 are alternately laminated on a silicon substrate 10, and then a trench 50 is formed through an anisotropic etching process.

[0081] Also, referring to FIG. 1, an etching solution according to the present invention is injected through the trench 50 region formed in the stacked structure 20, thereby etching the silicon nitride film 11 so that only the silicon oxide film 12 and the mask pattern layer 30 remain.

[0082] That is, the present invention uses an etching solution having an improved etching selectivity for a silicon nitride film relative to a silicon oxide film, thereby minimizing etching of the silicon oxide film 12 in the stack structure 20 and completely and selectively removing the silicon nitride film 11 in a sufficient time. Then, a semiconductor device can be manufactured through a subsequent process including a step of forming a gate electrode in the region where the silicon nitride film 11 has been removed.

[0083] <Method of manufacturing silicon nitride film etching solution> According to one aspect of the present invention, there is provided a method for producing a silicon nitride film etching solution, the method including the steps of: (a) mixing a silicon compound precursor with water to prepare a mixed solution, and then adding a hydroxide to the mixed solution to synthesize a silicon compound; (b) extracting the aqueous solution of the silicon compound synthesized in the step (a) from a first organic solvent, and then removing the first organic solvent; (c) mixing a result of the step (b) with a second organic solvent and refluxing the mixture; (d) lowering the temperature of the result of the step (c) to a range of 30°C to -40°C, and separating the crystallized solid compound; and (e) mixing the solid compound of the step (d) with an aqueous phosphoric acid solution to prepare a mixed solution.

[0084] First, the production method of the present invention includes the steps of (a) mixing a silicon compound precursor with water to produce a mixed liquid, and then adding a hydroxide to the mixed liquid to synthesize a silicon compound.

[0085] The silicon compound precursor is preferably a trialkoxysilane compound. For example, the trialkoxysilane compound may be 3-(2-aminoethylamino)propyltrimethoxysilane, allyltrimethoxysilane, or 3-(trimethoxysilyl)propyl. The hydroxide may be selected from LiOH, NaOH, KOH, Bd(OH)2, Mg(OH)2, or Ca(OH)2, without being particularly limited as long as it is a compound capable of providing hydroxide ions.

[0086] The equivalent ratio of the silicon compound precursor to the hydroxide may be 2:1 to 1:5. Preferably, the equivalent ratio of the silicon compound precursor to the hydroxide may be 1:1.

[0087] Next, the production method of the present invention includes the step (b) of extracting the aqueous solution of the silicon compound synthesized in the step (a) from the first organic solvent, and then removing the first organic solvent.

[0088] More specifically, the silicon compound synthesized by step (a) can be mixed with water to produce an aqueous solution of the silicon compound, and then extracted from the first organic solvent. For example, the first organic solvent can be ethyl acetate. The solvent may be selected from acetate, dichloromethane, chloroform, hexane, toluene and ether.

[0089] After the aqueous solution of the silicon compound is extracted with the first organic solvent, the first organic solvent is removed. The method for removing the first organic solvent is not particularly limited. For example, the first organic solvent is removed by a rotary evaporator. The solvent can be removed using an evaporator.

[0090] Next, the method of the present invention includes a step (c) of mixing the result of step (b) with a second organic solvent and refluxing the mixture.

[0091] More specifically, the silicon compound extracted in step (b) can be mixed with a second organic solvent and refluxed at high temperature. In step (c), both the silicon compound exhibiting cis stereochemistry and the silicon compound exhibiting trans stereochemistry extracted in step (b) can be dissolved in the second organic solvent. The type of the second organic solvent is not particularly limited, and examples thereof include hexane, benzene, and isopropyl methyl ether. methyl ether).

[0092] Next, the method of the present invention includes a step (d) of lowering the temperature of the result of step (c) to a range of 30° C. to −40° C., and isolating the crystallized solid compound.

[0093] More specifically, the silicon compounds exhibiting cis and trans stereochemistry dissolved in the non-polar solvent in step (c) can be cooled to a low temperature range of 30°C to -40°C to separate the crystallized solid compounds. Here, even when the temperature is lowered, the silicon compounds exhibiting cis stereochemistry are still dissolved in the non-polar solvent, whereas the silicon compounds exhibiting trans stereochemistry can be crystallized and exist as solid compounds. Thus, the silicon compounds exhibiting trans stereochemistry, which are the crystallized solid compounds, can be separated from the silicon compounds exhibiting cis stereochemistry.

[0094] Next, the production method of the present invention includes a step (e) of mixing the solid compound from step (d) with an aqueous phosphoric acid solution to produce a mixed solution.

[0095] The phosphoric acid aqueous solution can maintain the pH of the etching solution and suppress the silicon compounds present in the etching solution from converting into silicon-based particles. As an example, the phosphoric acid aqueous solution is preferably contained in an amount of 60 to 90 parts by weight per 100 parts by weight of the mixed solution.

[0096] When the etching solution produced according to the above-mentioned production method of the present invention is used, the etching rate of the silicon oxide film by the phosphoric acid aqueous solution can be reduced, and the etching selectivity ratio of the silicon oxide film to the silicon nitride film can be improved.

[0097] Specific examples of the present invention are presented below. However, the examples described herein are merely for the purpose of specifically illustrating or explaining the present invention, and the present invention should not be limited thereby.

[0098] Working Example Etching solution production Example 1 A silicon nitride film etching solution was prepared by mixing 85% by weight of phosphoric acid, 50 ppm of additive, and the remaining amount of water. The additive contained the following cis-type compound 1 and trans-type compound 2, and the content ratio of compound 1 to compound 2 was 9:1.

[0099] [Compound 1] TIFF0007623111000009.tif50134

[0100] [Compound 2] TIFF0007623111000010.tif50134

[0101] Example 2 A silicon nitride film etching solution was prepared in the same manner as in Example 1, except that the content ratio of compound 1 and compound 2 in Example 1 was 7:3.

[0102] Example 3 A silicon nitride film etching solution was prepared in the same manner as in Example 1, except that the content ratio of compound 1 and compound 2 in Example 1 was 5:5.

[0103] Example 4 A silicon nitride film etching solution was prepared in the same manner as in Example 1, except that the content ratio of compound 1 and compound 2 in Example 1 was 3:7.

[0104] Example 5 A silicon nitride film etching solution was prepared in the same manner as in Example 1, except that the content ratio of compound 1 and compound 2 in Example 1 was 1:9.

[0105] Comparative Example 1 A silicon nitride film etching solution was prepared in the same manner as in Example 1, except that only compound 1 of Example 1 was used as an additive.

[0106] Experimental Example A silicon oxide film (thermal oxide layer) and a silicon nitride film having a thickness of 500 Å were immersed in the silicon nitride film etching solution having the composition according to each of Examples 1 to 5 and Comparative Example 1 at 175° C. and etched for 10 minutes.

[0107] The thicknesses of the silicon oxide and silicon nitride films before and after etching were measured by ellipsometry (Nano-View, SE The etching rate was calculated by dividing the difference in thickness between the silicon oxide film and the silicon nitride film before and after etching by the etching time (10 minutes).

[0108] The etching rates measured using silicon nitride film etching solutions with different silica forms are shown in Table 1 below.

[0109] [Table 1] TIFF0007623111000011.tif82164

[0110] As shown in Table 1 above, the silicon nitride film etching solutions of Examples 1 to 5 can reduce the etching rate of a silicon oxide film compared to the silicon nitride film etching solution of Comparative Example 1, and this can be confirmed to improve the etching selectivity ratio of a silicon nitride film to a silicon oxide film.

[0111] In particular, as shown in Table 1, it can be seen that the higher the content ratio of the trans compound among the additives, the more the etching rate for the silicon oxide film can be reduced, and thus the etching selectivity ratio of the silicon oxide film to the silicon nitride film can be improved.

[0112] Although one embodiment of the present invention has been described above, a person having ordinary knowledge in the technical field can modify and change the present invention in various ways by adding, changing, deleting or adding components within the scope of the concept of the present invention described in the claims, and this can also be said to be within the scope of the rights of the present invention. [Explanation of symbols]

[0113] 10 Silicon substrate 11 Silicon nitride film 12 Silicon oxide film 20 Laminated structure 30 Mask Pattern Layer 50 Trench

Claims

1. an aqueous solution of phosphoric acid; and The compound represented by the following formula 1 is included: Silicon nitride etching solution: 【Chemistry 1】 In the above formula 1, X １ ~X ３ are each independently a hydroxy group, two of X 1 to X 3 are trans in stereochemical structure, R １ ~R ３ are each independently hydrogen, C １ -C ２０ Alkyl group, C ６ -C １２ It is selected from cycloalkyl, C 6 -C 30 aryl, and halogen.

2. The silicon nitride film etching solution according to claim 1, wherein the compound represented by Chemical Formula 1 is a compound represented by Chemical Formula 2 or Chemical Formula 3 below: 【Chemistry 2】 【Chemistry 3】 R in the above formula 2 and formula 3 １ ~R ３ are each independently hydrogen, C １ -C ２０ Alkyl group, C ６ -C １２ Cycloalkyl, C ６ -C ３０ It is selected from aryl and halogen.

3. The silicon nitride film etching solution contains an additive containing the compound represented by Chemical Formula 1 in an amount of 50 to 200,000 ppm. The silicon nitride film etching solution according to claim 1 .

4. The silicon nitride film etching solution further includes at least one fluorine-containing compound selected from hydrogen fluoride, ammonium fluoride, ammonium bifluoride, and ammonium bifluoride; The silicon nitride film etching solution according to claim 1 .

5. The silicon nitride film etching solution further includes a fluorine-containing compound having an ionic bond between an organic cation and a fluorine anion. The silicon nitride film etching solution according to claim 1 .

6. Aqueous phosphoric acid solution; Compound 1 of the following structure: Compound 2 of the following structure: The compound 1 and the compound 2 are mixed in a ratio of 1:9 to 9:

1. Silicon nitride etching solution: 【Chemistry 4】 Compound 1 【Chemistry 5】 Compound 2

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