Etching solution composition

Abstract

The present invention provides an etching solution composition which is capable of achieving a good balance between a high etching selectivity with respect to silicon nitride and suppression of silica deposition on a silicon oxide surface.　Provided is an inorganic-acid-based etching solution composition for selectively etching silicon nitride from a semiconductor containing silicon nitride and silicon oxide, said etching solution composition comprising an etching inhibitor that inhibits etching of silicon oxide and a deposition inhibitor that inhibits deposition of silica on a silicon oxide surface, wherein the etching inhibitor includes a first etching inhibitor that includes, in the molecular structure thereof, not more than three alkoxy groups, hydroxyl groups, and / or functional groups that are a hydroxyl group precursor, and a second etching inhibitor that includes, in the molecular structure thereof, not less than four alkoxy groups, hydroxyl groups, and / or functional groups that are a hydroxyl group precursor.

Description

[Technical Field]

[0001] The present invention relates to an inorganic acid-based etching solution composition for selectively etching silicon nitride from a semiconductor containing silicon nitride and silicon oxide. [Background technology]

[0002] With the increasing integration and capacity of semiconductor circuits in recent years, there is a growing demand for more precise etching technologies. For example, in the manufacturing of NAND flash memory with a three-dimensional structure (3D NAND), silicon nitride films and silicon oxide films are alternately stacked and then immersed in an etching solution. In this process, it is necessary to precisely remove only the silicon nitride film. Therefore, various etching solutions (compositions) have been developed to achieve high etching selectivity in etching processes.

[0003] For example, the etching solution composition described in Patent Document 1 is used in the manufacturing process of three-dimensional semiconductors and is a composition comprising a solution containing silica and alkali, phosphoric acid, and water. According to Patent Document 1, using such an etching solution composition suppresses the etching of silicon oxide films and improves the etching selectivity of silicon nitride films (see paragraph 0013 of the specification of Patent Document 1).

[0004] Another technology, as described in Patent Document 2, is an etching solution composition comprising water, phosphoric acid, and a hydroxyl group-containing solvent. According to Patent Document 2, examples of hydroxyl group-containing solvents include polyols, glycols, and monohydric alcohols, and these components function to protect the silicon oxide film, so that the silicon nitride film is etched preferentially and selectively (see paragraph 0025 of the specification of Patent Document 2). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-96160 [Patent Document 2] Japanese Patent Publication No. 2018-207108 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Incidentally, when silicon nitride is etched with an etching solution composition containing phosphoric acid and water, ammonium phosphate [(NH4)3PO4)] and silicate [SiO2] are released into the solution. x (OH) 4-2x ] n These are formed, but when the silica concentration in the liquid increases, they dehydrate and condense to form silica [SiO2]. x This makes it easier for silicon dioxide to precipitate on the surface. Such precipitation can cause malfunctions such as short circuits and faulty wiring in semiconductor products, so it must be eliminated as much as possible.

[0007] Furthermore, in order to selectively etch silicon nitride from a semiconductor containing silicon nitride and silicon oxide, it is necessary to increase the etching rate for silicon nitride while keeping the etching rate for silicon oxide low. However, since silicon oxide is also etched by water, when using an aqueous etching solution composition, measures to suppress the etching of silicon oxide must be considered.

[0008] Regarding the above point, Patent Document 1 states that "etching of the silicon oxide film is suppressed and the etching selectivity of the silicon nitride film is improved," but the details of the mechanism by which this effect is achieved are unknown (see paragraph 0013 of the same document). Furthermore, since the etching solution composition in Patent Document 1 originally contains silicic acid, it is thought that etching silicon nitride increases the concentration of silicic acid in the solution, making it easier for silica to precipitate on the surface of the silicon oxide.

[0009] The etching solution composition of Patent Document 2 is said to protect the silicon oxide film with a hydroxyl group-containing solvent. However, the etching selectivity of silicon nitride is not sufficiently high in the first place. According to the illustrated data, the highest selectivity ratio between silicon nitride and silicon oxide remains at 137 (see FIGS. 2, 4, and 6 of the same document). Further, in Patent Document 2, water contained in the etching solution composition is recognized as functioning as a solvent, a residue remover, a viscosity modifier, and a diluent (see paragraph 0021 of the same document). However, no recognition or consideration has been given to the effect of water on etching silicon oxide.

[0010] Therefore, with conventional etching solution compositions, it is not easy to increase the selectivity ratio while suppressing the deposition of silica on the surface of silicon oxide, and there still remains room for improvement.

[0011] The present invention has been made in view of the above problems, and an object thereof is to provide an etching solution composition capable of achieving both high etching selectivity for silicon nitride and suppression of the deposition of silica on the surface of silicon oxide.

Means for Solving the Problems

[0012] The characteristic configuration of the etching solution composition according to the present invention for solving the above problems is an inorganic acid-based etching solution composition for selectively etching silicon nitride from a semiconductor containing silicon nitride and silicon oxide, an etching inhibitor for suppressing the etching of silicon oxide, and a deposition inhibitor for suppressing the deposition of silica on the surface of silicon oxide and containing the etching inhibitor includes a first etching inhibitor having 3 or less alkoxy groups, hydroxyl groups, and / or functional groups that are precursors of hydroxyl groups in the molecular structure, and a second etching inhibitor having 4 or more alkoxy groups, hydroxyl groups, and / or functional groups that are precursors of hydroxyl groups in the molecular structure.

[0013] According to the etching liquid composition of this configuration, while the etching inhibitor suppresses the etching of silicon oxide by water, silicon nitride is mainly etched by inorganic acid. Therefore, in a semiconductor containing silicon nitride and silicon oxide, the etching selectivity for silicon nitride can be improved. Here, when silicon nitride is not etched, since the concentration of Si in the liquid is low, there is concern that the etching rate for silicon oxide will increase. However, as the etching inhibitor, a first etching inhibitor having 3 or less alkoxy groups, hydroxyl groups, and / or functional groups that are precursors of hydroxyl groups in the molecular structure, and a second etching inhibitor having 4 or more alkoxy groups, hydroxyl groups, and / or functional groups that are precursors of hydroxyl groups in the molecular structure are used. By doing so, the etching of silicon oxide can be continuously suppressed, and the etching selectivity for silicon nitride can be maintained over a long period without being affected by the concentration of Si in the liquid. In addition, since the precipitation inhibitor can suppress the precipitation of silica on the surface of silicon oxide, it is possible to prevent problems such as short circuits and wiring defects from occurring in semiconductor products.

[0014] In the etching liquid composition according to the present invention, It is preferable that the first etching inhibitor is a silane compound having an amino group.

[0015] According to the etching liquid composition of this configuration, by selecting a silane compound having an amino group as the first etching inhibitor, both the etching inhibition effect of silicon oxide by the etching inhibitor and the precipitation inhibition effect of silica on the surface of silicon oxide by the precipitation inhibitor can be achieved, and the etching selectivity for silicon nitride can be improved.

[0016] In the etching liquid composition according to the present invention, The first etching inhibitor preferably contains at least one selected from the group consisting of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and hydrolysates of these alkoxysilanes.

[0017] According to the etching solution composition of this configuration, since it contains a compound suitable as the first etching inhibitor, it is possible to achieve both the etching inhibitory effect on silicon oxide by the etching inhibitor and the precipitation inhibitory effect on silica deposition on the surface of silicon oxide by the precipitation inhibitor, thereby further improving the etching selectivity for silicon nitride.

[0018] In the etching solution composition according to the present invention, The second etching inhibitor is preferably a silane compound having at least one functional group selected from the group consisting of alkyl groups, amino groups, and halogen groups.

[0019] According to the etching solution composition of this configuration, by selecting a silane compound having at least one functional group selected from the group consisting of alkyl groups, amino groups, and halogen groups as the second etching inhibitor, it is possible to achieve both the etching inhibitory effect on silicon oxide by the etching inhibitor and the precipitation inhibitory effect on silica deposition on the surface of silicon oxide by the precipitation inhibitor, thereby improving the etching selectivity for silicon nitride.

[0020] In the etching solution composition according to the present invention, The second etching inhibitor has the following chemical structure (1):

[0021] [ka] The chemical structure of 1,3-dimethyltetramethoxydisiloxane shown below is (2):

[0022] [ka] The siloxane compound shown below has the following chemical structure (3):

[0023] [ka] The siloxane compound shown below has the following chemical structure (4):

[0024] [ka] It is preferable to include at least one selected from the group consisting of hexamethoxydisiloxane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, silicon tetrachloride, and hexachlorodisilane.

[0025] According to this etching solution composition, since it contains a compound suitable as a second etching inhibitor, it is possible to achieve both the etching inhibitory effect on silicon oxide by the etching inhibitor and the precipitation inhibitory effect on silica deposition on the silicon oxide surface by the precipitation inhibitor, thereby further improving the etching selectivity for silicon nitride.

[0026] In the etching solution composition according to the present invention, The precipitation inhibitor preferably contains hydrazides.

[0027] According to this etching solution composition, by selecting hydrazides as the precipitation inhibitor, an excellent effect of suppressing silica precipitation on the silicon oxide surface can be obtained.

[0028] In the etching solution composition according to the present invention, The hydrazides preferably include at least one selected from the group consisting of adipic acid dihydrazide, succinate dihydrazide, acetohydrazide chloride, 2,2-dimethylhydrazide succinate, and azelaic acid dihydrazide.

[0029] According to this etching solution composition, since it contains compounds suitable as precipitation inhibitors, a better effect in inhibiting silica precipitation on the silicon oxide surface can be obtained.

[0030] In the etching solution composition according to the present invention, In its unused state, it is preferable that the liquid does not contain silicon nitride-derived Si.

[0031] According to this etching solution composition, by using a new etching solution composition that does not contain silicon nitride-derived Si in its unused state, the etching selectivity for silicon nitride can be maintained over a long period of time.

[0032] In the etching solution composition according to the present invention, It is preferable that the solution can be repeatedly used until the concentration of Si derived from silicon nitride in the solution reaches at least 3000 ppm.

[0033] This etching solution composition can be used until the concentration of silicon nitride-derived Si in the solution reaches at least 3000 ppm. This significantly extends the lifespan of the solution compared to conventional etching solutions (phosphoric acid), and allows for increased etching output with less usage, making it highly economical and environmentally friendly. Furthermore, the etching inhibitor contained in the etching solution composition suppresses the etching of the silicon oxide film, resulting in high etching selectivity for silicon nitride. In addition, the selectivity ratio [R1 / R2] can be greatly improved while suppressing silica deposition on the silicon oxide surface.

[0034] In the etching solution composition according to the present invention, It is preferable that the selectivity ratio [R1 / R2], which is the ratio of the etching rate of silicon nitride [R1] to the etching rate of silicon oxide [R2], is set to 5.3 times or more the selectivity ratio of the etching solution consisting only of the inorganic acid.

[0035] With this etching solution composition, by setting the selectivity ratio [R1 / R2] to 5.3 times or more compared to the selectivity ratio of an etching solution consisting only of inorganic acids, it is possible to achieve both high etching selectivity for silicon nitride and suppression of silica deposition on the silicon oxide surface, while performing etching in a short time. [Modes for carrying out the invention]

[0036] Embodiments of the etching solution composition according to the present invention will be described below. However, the present invention is not intended to be limited to the following embodiments.

[0037] [Etching solution composition] The etching solution composition according to the present invention is used to selectively etch silicon nitride from a semiconductor containing silicon nitride and silicon oxide. The components included in the etching solution composition are described below.

[0038] <Inorganic acid> The etching solution composition according to the present invention is based on an inorganic acid. Examples of inorganic acids include phosphoric acid, sulfuric acid, nitric acid, hydrochloric acid, and mixed acids of these inorganic acids. Of these inorganic acids, phosphoric acid is preferred. When used diluted, phosphoric acid is in the form of an aqueous solution, and its concentration is preferably 50 to 100% by weight (wt%), more preferably 70 to 95% by weight, and even more preferably 85 to 95% by weight. Note that the phosphoric acid only needs to be adjusted to the above concentration when using the etching solution composition. For example, the appropriate concentration can be achieved by concentrating a stock solution containing a low-concentration aqueous phosphoric acid solution at or before use, diluting a stock solution containing phosphoric acid with a concentration exceeding 100% by weight (strong phosphoric acid) with water at or before use, or by dissolving anhydrous phosphoric acid (P2O5) in water at or before use.

[0039] <Etching inhibitor> The etching solution composition according to the present invention contains an etching inhibitor that suppresses the etching of silicon dioxide. The etching inhibitor includes multiple types of etching inhibitors with different chemical structures. In this embodiment, the etching inhibitor includes a first etching inhibitor and a second etching inhibitor. The first etching inhibitor is a compound having three or fewer alkoxy groups, hydroxyl groups, and / or functional groups that are precursors to hydroxyl groups in its molecular structure, and is preferably a silane compound having an amino group. The second etching inhibitor is a compound having four or more alkoxy groups, hydroxyl groups, and / or functional groups that are precursors to hydroxyl groups in its molecular structure, and is preferably a silane compound having at least one functional group selected from the group consisting of alkyl groups, amino groups, and halogen groups. For compounds having hydroxyl groups, any compound that can ultimately change to have hydroxyl groups in the solution is acceptable.

[0040] [First etching inhibitor] The first etching inhibitors include methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, dimethoxydiphenylsilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, 1,6-bis(trimethoxysilyl)hexane, vinyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and N-2-(aminoethyl)-4-aminobutyltrimethoxysilane. Examples include N-2-(aminoethyl)-5-aminopentyltrimethoxysilane, N-2-(aminoethyl)-6-aminohexyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane, as well as the hydrochlorides of each of the above aminosilanes, tris-(trimethoxysilylpropyl)isocyanurate, 3-mercaptopropylmethyldimethoxysilane, 3-isocyanatetopropyltriethoxysilane, and 3-trimethoxysilylpropyl succinic anhydride, as well as hydrolysates of each of the above alkoxysilanes. Of these first etching inhibitors, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, as well as hydrolysates of these alkoxysilanes, are preferred. The above first etching inhibitors may be used individually or as a mixture of two or more.

[0041] [Second etching inhibitor] The second etching inhibitor generally has the chemical structure shown in the following formula (I).

[0042] [ka] Here, R1 to R6 in formula (I) are substituents, and at least four of these substituents are at least one specific substituent selected from the group consisting of alkoxy groups, hydroxyl groups, and chlorine. The substituents other than these specific substituents are at least one substituent selected from the group consisting of alkyl groups, aryl groups, carbonyl groups, carboxyl groups, amino groups, ethylenediamine groups, and derivatives or complex groups of these substituents. In formula (I), X is either "O" (oxygen atom) or "-" (single bond). In formula (I), n is an integer from 0 to 3. Thus, the second etching inhibitor can be a compound having an alkoxy group (siloxane compound or disilane compound, hereinafter the same) and a compound having a hydroxyl group, as well as a compound having chlorine. Note that the compound having an alkoxy group and the compound having chlorine are hydrolyzed to ultimately become a compound having a hydroxyl group.

[0043] A specific example of a second etching inhibitor is the following chemical structure (1):

[0044] [ka] The chemical structure of 1,3-dimethyltetramethoxydisiloxane shown below is (2):

[0045] [ka] The siloxane compound shown below has the following chemical structure (3):

[0046] [ka] The siloxane compound shown below has the following chemical structure (4):

[0047] [ka] The following are shown: hexamethoxydisiloxane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, hexamethoxydisilane, hexaethoxydisilane, hexasubtoxoxydisilane, hexamethoxydisiloxane, hexaethoxydisiloxane, hexasubtoxoxydisiloxane, 1,3-dimethyltetraethoxydisiloxane, 1,3-dimethyltetrabutoxydisiloxane, 1,3-diethyltetramethoxydisiloxane, 1,3-diethyltetraethoxydisiloxane, 1,3 Examples include diethyltetrabutoxydisiloxane, 1,3-divinyltetramethoxydisiloxane, 1,3-divinyltetraethoxydisiloxane, 1,3-divinyltetrabutoxydisiloxane, 1,3-bis(3-aminopropyl)tetramethoxydisiloxane, silicon tetrachloride, hexachlorodisilane, hexachlorodisiloxane, 1,3-dimethyltetrachlorodisiloxane, 1,3-diethyltetrachlorodisiloxane, and 1,3-dibutyltetrachlorodisiloxane. Incidentally, commercially available siloxane compounds include the silane coupling agents "X-12-1098", "X-12-1135", "KBP-64", and "KBP-90" manufactured by Shin-Etsu Chemical Co., Ltd. The above second etching inhibitor may be used alone or as a mixture of two or more.

[0048] [Content of etching inhibitor] The content of etching inhibitors in the etching solution composition is preferably 0.5 to 20% by weight, more preferably 1 to 20% by weight, and even more preferably 1 to 6% by weight for the first etching inhibitor. For the second etching inhibitor, it is preferably 0.01 to 5% by weight, more preferably 0.01 to 1% by weight, and even more preferably 0.09 to 0.6% by weight.

[0049] <Precipitation inhibitor> The etching solution composition according to the present invention contains a precipitation inhibitor that suppresses the deposition of silica on the surface of silicon oxide. Examples of precipitation inhibitors include hydrazine compounds, pyrazoles, triazoles, hydrazides, compounds having an imidazole skeleton, compounds having a pyrrolidine skeleton, compounds having a piperidine skeleton, compounds having a morpholine skeleton, compounds having a pyridine skeleton, phosphonic acid compounds, compounds having a quaternary ammonium skeleton, compounds having a pyrimidine skeleton, compounds having a purine skeleton, and compounds having a urea skeleton, with hydrazides being preferred. The above compounds and types may be used individually or as a mixture of two or more. Using two or more different precipitation inhibitors can be very useful not only in terms of performance in the etching process, but also in terms of extending the lifespan of the solution and reducing costs. The content of the precipitation inhibitor in the etching solution composition is preferably 0.1 to 1% by weight, and more preferably 0.3 to 0.4% by weight.

[0050] [Hydrazine compounds] Examples of hydrazine compounds include hydrazine, butylhydrazine, isopropylhydrazine, benzylhydrazine, N,N-dimethylhydrazine, 1,2-diacetylhydrazine, phenylhydrazine, N,N-dicarbamoylhydrazine, hydrazine sulfate, hydrazine monohydrochloride, hydrazine dihydrochloride, butylhydrazine hydrochloride, hydrazine carbonate, and hydrazine monobromide. The above hydrazine compounds may be used individually or as a mixture of two or more.

[0051] [Pyrazoles] Examples of pyrazoles include 3,5-dimethylpyrazole and 3-methyl-5-pyrazone. These pyrazoles may be used individually or as a mixture of two or more.

[0052] [Triazoles] Examples of triazoles include 4-amino-1,2,4-triazole, 1,2,4-triazole, 1,2,3-triazole, 1-hydroxybenzotriazole, and 3-mercapto-1,2,4-triazole. These triazoles may be used individually or as a mixture of two or more.

[0053] [Hydrazides] Hydrazides include propionic acid hydrazide, lauryl acid hydrazide, salicylic acid hydrazide, formhydrazide, acetohydrazide, acetohydrazide chloride, p-hydroxybenzoic acid hydrazide, naphthoate hydrazide, 3-hydroxy-2-naphthoate hydrazide, benzhydrazide, carbodihydrazide, oxalate dihydrazide, malonate dihydrazide, succinate dihydrazide, 2,2-dimethyl succinate dihydrazide, glutarate dihydrazide, adipic acid dihydrazide, azelaic acid dihydrazide, sebatic acid dihydrazide, dodecanedioate dihydrazide, and maleate dihydrazide. Examples of hydrazides include dihydrazides, fumarate dihydrazides, tartrate dihydrazides, malate dihydrazides, diglycolate dihydrazides, isophthalate dihydrazides, terephthalate dihydrazides, 2,6-naphthalenedicarboxylic acid dihydrazides, 2,6-naphthoate dihydrazides, citrate trihydrazides, pyromellitic acid trihydrazides, 1,2,4-benzenetricarboxylic acid trihydrazides, nitrilotriacetate trihydrazides, 1,3,5-cyclohexanetricarboxylic acid trihydrazides, ethylenediaminetetraacetate tetrahydrazides, and 1,4,5,8-naphthoate tetrahydrazides. Among these hydrazides, adipic acid dihydrazides, succinate dihydrazides, acetohydrazide chloride, 2,2-dimethyl succinate dihydrazides, and azelaic acid dihydrazides are preferred. The hydrazides mentioned above may be used individually or as a mixture of two or more.

[0054] [Compounds containing an imidazole skeleton] Compounds having an imidazole skeleton include imidazole, imidazole carboxylic acid, imidourea, diazolidinylurea, 3-(2-oxoimidazolidine-1-yl)benzoic acid, and imidazole hydrochloride, as well as imidazolium salts such as 1-ethyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1,3-dimethylimidazolium methyl sulfate, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-octylimidazolium tetrafluoroborate, 1,3-dimethylimidazolium dimethyl phosphate, 1-ethyl-3-methylimidazolium tetrafluoroboric acid, and 1-ethyl-3-methylimidazolium hexafluorophosphate. The above compounds having an imidazole skeleton may be used individually or as a mixture of two or more.

[0055] [Compounds containing a pyrrolidine skeleton] Compounds having a pyrrolidine skeleton include pyrrolidine, 2-pyrrolidone, N-methylpyrrolidone, N-vinyl-2-pyrrolidone, pyroglutamic acid, and piracetam, as well as pyrrolidinium salts such as 1-ethyl-1-methylpyrrolidinium chloride, 1-butyl-1-methylpyrrolidinium chloride, 1-ethyl-1-methylpyrrolidinium acetate, 1-ethyl-1-methylpyrrolidinium tetrafluoroboric acid, 1-butyl-1-methylpyrrolidinium tetrafluoroboric acid, 1-ethyl-1-methylpyrrolidinium hexafluorophosphate, and 1-butyl-1-methylpyrrolidinium hexafluorophosphate. The above-mentioned compounds having a pyrrolidine skeleton may be used individually or as a mixture of two or more.

[0056] [Compounds containing a piperidine skeleton] Compounds having a piperidine skeleton include piperidine, ethyl piperidine-4-carboxylate, piperidine-2-ylacetic acid, and methyl piperidine-4-carboxylate, as well as piperidinium salts such as (piperidinium-1-ylmethyl)trifluoroborate, 1-butyl-1-methylpiperidinium bromide, and 1-butyl-1-methylpiperidinium bisimide. The above compounds having a piperidine skeleton may be used individually or as a mixture of two or more.

[0057] [Compounds containing a morpholine skeleton] Compounds having a morpholine skeleton include morpholine, morpholine-2-ylmethanol, morpholine-3-one, morpholine-4-carbothioamide, morpholine-4-ylacetic acid, and morpholine-4-ylethyl acetate, as well as morphonium salts such as 4-ethyl-4-methylmorpholinium bromide and 4-(2-ethoxyethyl)-4-methylmorpholinium bisimide. The above compounds having a morpholine skeleton may be used individually or as a mixture of two or more.

[0058] [Compounds containing a pyridine skeleton] Compounds having a pyridine skeleton include pyridine, N,N-dimethyl-4-aminopyridine, bipyridine, 2,6-lutidine, and pyridinium p-toluenesulfonate, as well as pyridinium salts such as 1-butyl-3-methylpyridium chloride, 1-butylpyridium tetrafluoroboric acid, and 1-butylpyridium hexafluorophosphate. The above-mentioned compounds having a pyridine skeleton may be used individually or as a mixture of two or more.

[0059] [Phosphonic acid compounds] Examples of phosphonic acid compounds include phosphonic acid, diphenyl phosphonate, butyl phosphonate, dipentyl phosphonate, and ammonium phosphate, as well as phosphonium salts such as tetrabutylphosphonium hexafluorophosphate, tetrabutylphosphonium bisimide, and tetrabutylphosphonium bromide. The above phosphonic acid compounds may be used individually or as a mixture of two or more.

[0060] [Compounds having a quaternary ammonium skeleton] Compounds having a quaternary ammonium skeleton include tetramethylammonium chloride, tetrabutylammonium chloride, tetramethylammonium bromide, tetramethylammonium hydroxide, tetramethylammonium iodide, tetrabutylammonium bromide, tetrabutylammonium bisulfate, tetramethylammonium hexafluorophosphate, tetrabutylammonium hexafluorophosphate, and choline acetate. The above compounds having a quaternary ammonium skeleton may be used individually or as a mixture of two or more.

[0061] [Compounds containing a pyrimidine skeleton] Compounds having a pyrimidine skeleton include thymine, cytosine, uracil, and the nucleosides, ribonucleosides, and deoxyribonucleosides of each of the above compounds. The above compounds having a pyrimidine skeleton may be used individually or as a mixture of two or more.

[0062] [Compounds containing a purine skeleton] Compounds having a purine skeleton include purines, adenine, guanine, uric acid, caffeine, hypoxanthine, xanthine, theophylline, theobromine, isoguanine, and nucleosides, ribonucleotides, and deoxyribonucleotides of each of the above compounds. The above compounds having a purine skeleton may be used individually or as a mixture of two or more.

[0063] [Compounds with a urea skeleton] Examples of compounds having a urea skeleton include urea, hydroxyurea, N,N-diethylthiourea, N,N-dibutylthiourea, biurea, biuret, and N-amidinothiourea. These compounds having a urea skeleton may be used individually or as a mixture of two or more.

[0064] [Preparation of etching solution composition] The etching solution composition according to the present invention is prepared by adding an etching inhibitor and a precipitation inhibitor to a base inorganic acid. Here, the etching inhibitor and precipitation inhibitor can be added directly to the inorganic acid, or they may be added to the inorganic acid after being dissolved or suspended in a solvent. The addition of the etching inhibitor and precipitation inhibitor to the inorganic acid may be carried out at room temperature or while the solution is heated.

[0065] <Solvent> As solvents for dissolving or suspending the etching inhibitor and the precipitation inhibitor, there are water, alcohols such as methanol, ethanol, 2-propanol, butanol, octanol, benzyl alcohol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 2,2,2-trifluoroethanol, ethers such as diethyl ether, diisopropyl ether, dibutyl ether, cyclopentyl methyl ether (CPME), tetrahydrofuran (THF), 2-methyltetrahydrofuran, 1,4-dioxane, dimethoxyethane, carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 4-fluoroethylene carbonate, esters such as methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, γ-lactone, nitriles such as acetonitrile, propionitrile, valeronitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, benzonitrile, amides such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), ureas such as dimethyl sulfoxide (DMSO), hexamethylphosphoric triamide (HMPA), N,N,N’,N’-tetramethylurea (TMU), N,N’-dimethylpropyleneurea (DMPU), and ionic liquids such as imidazolium salts, pyrrolidinium salts, piperidinium salts, pyridinium salts, morphonium salts, phosphonium salts, quaternary ammonium salts, sulfonium salts, etc. Regarding ionic liquids, the cation includes an imidazolium skeleton, a pyrrolidinium skeleton, a piperidinium skeleton, a morphonium skeleton, a pyridinium skeleton, a quaternary phosphonium skeleton, a quaternary ammonium skeleton, and a sulfonium skeleton, etc., and the anion includes Br - , BF4 - , PF6 - , (CN)2N - , Cl - , I - , (CF3SO2)N - , (F2SO2)N - , CH3COO- HSO4 - (CH3)2PO4 - CF3COO - CH3SO3 - CF3SO3 - , and SCN - These are some examples. The above solvents may be used individually or as a mixture of two or more.

[0066] <Surfactants> When dissolving or suspending etching inhibitors and precipitation inhibitors in a solvent, surfactants can also be used in combination. Cationic surfactants, anionic surfactants, amphoteric surfactants, and nonionic surfactants can all be used, and combinations of these surfactants can also be used.

[0067] A key feature of the etching solution composition according to the present invention is that the concentration of silicon nitride-derived Si in the solution can be used within a predetermined concentration range or up to a predetermined concentration. Conventional etching solutions (phosphoric acid) increase in concentration of silicon nitride-derived Si as the usage time or number of uses increases. When the concentration of Si reaches a certain level, silica precipitation occurs, requiring disposal as a fatigue solution or a process of recovering and regenerating the fatigue solution. However, the etching solution composition according to the present invention can suppress silica precipitation even when the concentration of silicon nitride-derived Si in the solution increases. As a result, the lifespan of the solution is significantly extended compared to conventional etching solutions (phosphoric acid), and the amount of etching treatment is increased with a small amount of usage, making it very economical and environmentally friendly. Furthermore, since etching of the silicon oxide film is suppressed by the etching inhibitor contained in the etching solution composition, high etching selectivity for silicon nitride can be achieved.

[0068] Here, we will explain the concentration of Si derived from silicon nitride in the solution (a predetermined concentration). As described above, the etching solution composition according to the present invention can be used within a predetermined concentration range for the concentration of Si derived from silicon nitride in the solution (i.e., it can be used even if the concentration of Si, which increases due to the etching of silicon nitride, reaches a concentration significantly higher than conventional methods). However, the Si component in the etching solution composition also includes components derived from silane coupling agents, etc. However, silane coupling agents, etc. maintain a stable structure even at arbitrary high temperatures in the etching solution, and the Si component derived from silane coupling agents, etc. does not contribute to a decrease in the performance of the etching solution composition due to precipitation as silica. Furthermore, the Si component derived from the silicon nitride film is contained in silicic acid [SiO2] in the etching solution. x (OH) 4-2x ] n It exists in this state. In this case, highly selective etching is possible until the Si concentration derived from silicon nitride reaches at least 3000 ppm (for example, at any concentration between 0 and 3000 ppm), which is the predetermined concentration mentioned above. In this specification, the unit (ppm) of the Si concentration derived from silicon nitride in the etching solution is given in units of weight (mg / kg).

[0069] The etching solution composition according to the present invention, prepared as described above, has a selectivity ratio [R1 / R2], which is the ratio of the etching rate of silicon nitride [R1] to the etching rate of silicon oxide [R2], of 5.3 times or more compared to the selectivity ratio of an etching solution consisting only of inorganic acids, thus exhibiting high etching selectivity for silicon nitride. With an etching solution composition having such a high selectivity ratio [R1 / R2], it is possible to perform etching in a short time while simultaneously achieving high etching selectivity for silicon nitride and suppressing the deposition of silica on the surface of silicon oxide. The ratio of the selectivity ratio [R1 / R2] of the etching solution composition of the present invention to the selectivity ratio of an etching solution consisting only of inorganic acids is preferably 9 times or more, and more preferably 18 times or more. Performing etching using such an etching solution composition with a high selectivity ratio [R1 / R2] compared to an etching solution consisting only of inorganic acids can prevent defects such as short circuits and wiring failures from occurring in semiconductor products, which is a very significant advantage in the industrial production (process) of semiconductor products. [Examples]

[0070] Examples of the etching solution composition according to the present invention will be described. In these examples, an etching test was conducted that simulated a part of the 3D NAND manufacturing process in order to confirm the performance of the etching solution composition.

[0071] <Preparation of Etching Solution Composition> As etching solution compositions based on phosphoric acid according to the present invention, etching solution compositions according to Examples 1 to 34 were prepared, each containing a first etching inhibitor, a second etching inhibitor, and a precipitation inhibitor as etching inhibitors. For comparison, etching solution compositions according to Comparative Examples 1 to 6 and 14 to 16 were prepared, each containing only the first etching inhibitor and a precipitation inhibitor as etching inhibitors, and etching solution compositions according to Comparative Examples 7 to 13 and 17 to 19 were prepared, each containing only the second etching inhibitor and a precipitation inhibitor as etching inhibitors. Furthermore, for reference, an etching solution (phosphoric acid) according to Reference Example 1, which does not contain either an etching inhibitor or a precipitation inhibitor, was prepared. The preparation methods for each etching solution composition or etching solution will be described below.

[0072] [Example 1] An aqueous phosphoric acid solution (manufactured by Rasa Industries, Ltd., hereafter referred to as "85% phosphoric acid") adjusted to a concentration of 85 wt% was used as the base inorganic acid, and this was concentrated to obtain 87% phosphoric acid. To this 87% phosphoric acid, 3.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as the first etching inhibitor, 0.20 wt% of 1,3-dimethyltetramethoxydisiloxane (manufactured by Fluorochem Ltd.), having the following chemical structural formula (1), was added as the second etching inhibitor, and 0.30 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as the precipitation inhibitor. Dissolving these in the solution provided the etching solution composition of Example 1.

[0073] [ka]

[0074] [Example 2] The etching solution composition of Example 2 was prepared by pre-dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 1, and adjusting the concentration of silicon nitride-derived Si in the solution to 200 ppm. The concentration of silicon nitride-derived Si in the solution was measured using the "Method for Measuring Silicon Nitride-Derived Si Concentration" described below (the same method was used in subsequent examples and comparative examples).

[0075] [Example 3] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 3.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a first etching inhibitor, 0.09 wt% of a siloxane compound having the following chemical structural formula (2) was added as a second etching inhibitor, and 0.30 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. The mixture was then dissolved in the solution to obtain the etching solution composition of Example 3.

[0076] [ka]

[0077] [Example 4] The etching solution composition of Example 4 was prepared by pre-dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 3 and adjusting the concentration of Si derived from silicon nitride in the solution to 200 ppm.

[0078] [Example 5] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 4.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a first etching inhibitor, 0.60 wt% of a siloxane compound having the following chemical structural formula (3) was added as a second etching inhibitor, and 0.30 wt% of dihydrazide succinate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. The mixture was then dissolved in the solution to obtain the etching solution composition of Example 5.

[0079] [ka]

[0080] [Example 6] The etching solution composition of Example 6 was prepared by pre-dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 5 and adjusting the concentration of Si derived from silicon nitride in the solution to 200 ppm.

[0081] [Example 7] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 4.00 wt% of 3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a first etching inhibitor, 0.20 wt% of 1,3-dimethyltetramethoxydisiloxane (manufactured by Fluorochem Ltd.), shown in chemical structural formula (1), was added as a second etching inhibitor, and 0.30 wt% of dihydrazide succinate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. The mixture was then dissolved in the solution to obtain the etching solution composition of Example 7.

[0082] [Example 8] The etching solution composition of Example 8 was prepared by pre-dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 7 and adjusting the concentration of Si derived from silicon nitride in the solution to 200 ppm.

[0083] [Example 9] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 4.00 wt% of 3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a first etching inhibitor, 0.09 wt% of the siloxane compound shown in chemical structural formula (2) was added as a second etching inhibitor, and 0.30 wt% of acethydrazide chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. The mixture was then dissolved in the solution to obtain the etching solution composition of Example 9.

[0084] [Example 10] The etching solution composition of Example 9 was prepared by pre-dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 9 and adjusting the concentration of Si derived from silicon nitride in the solution to 200 ppm.

[0085] [Example 11] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 4.00 wt% of 3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a first etching inhibitor, 0.09 wt% of the siloxane compound shown in chemical structural formula (2) was added as a second etching inhibitor, and 0.30 wt% of 2,2-dimethylhydrazide succinate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. The mixture was then dissolved in the solution to obtain the etching solution composition of Example 11.

[0086] [Example 12] The etching solution composition of Example 12 was prepared by pre-dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 11 and adjusting the concentration of Si derived from silicon nitride in the solution to 200 ppm.

[0087] [Example 13] To 87% phosphoric acid obtained using the same procedure as in Example 1, 3.00 wt% of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a first etching inhibitor, 0.12 wt% of the siloxane compound shown in chemical structural formula (2) was added as a second etching inhibitor, and 0.30 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. The mixture was then dissolved in the solution to obtain the etching solution composition of Example 13.

[0088] [Example 14] The etching solution composition of Example 14 was prepared by pre-dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 13 and adjusting the concentration of Si derived from silicon nitride in the solution to 200 ppm.

[0089] [Example 15] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 6.00 wt% of N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a first etching inhibitor, 0.09 wt% of the siloxane compound shown in chemical structural formula (2) was added as a second etching inhibitor, and 0.30 wt% of acethydrazide chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. The mixture was then dissolved in the solution to obtain the etching solution composition of Example 15.

[0090] [Example 16] The etching solution composition of Example 16 was prepared by pre-dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 15 and adjusting the concentration of Si derived from silicon nitride in the solution to 200 ppm.

[0091] [Example 17] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 4.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a first etching inhibitor, 0.04 wt% of tetramethoxysilane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a second etching inhibitor, and 0.30 wt% of azelaic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a precipitation inhibitor. The mixture was then dissolved in the solution to obtain the etching solution composition of Example 17.

[0092] [Example 18] The etching solution composition of Example 18 was prepared by pre-dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 17 and adjusting the concentration of Si derived from silicon nitride in the solution to 200 ppm.

[0093] [Example 19] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 4.00 wt% of 3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a first etching inhibitor, 0.20 wt% of tetraethoxysilane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a second etching inhibitor, and 0.40 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a precipitation inhibitor. The mixture was then dissolved in the solution to obtain the etching solution composition of Example 19.

[0094] [Example 20] The etching solution composition of Example 20 was prepared by pre-dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 19 and adjusting the concentration of Si derived from silicon nitride in the solution to 200 ppm.

[0095] [Example 21] To 87% phosphoric acid obtained using the same procedure as in Example 1, 4.00 wt% of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a first etching inhibitor, 0.30 wt% of tetrabutoxysilane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a second etching inhibitor, and 0.40 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a precipitation inhibitor were added, and the mixture was dissolved in the solution to obtain the etching solution composition of Example 21.

[0096] [Example 22] The etching solution composition of Example 22 was prepared by pre-dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 21 and adjusting the concentration of Si derived from silicon nitride in the solution to 200 ppm.

[0097] [Example 23] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 4.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a first etching inhibitor, 0.10 wt% of silicon tetrachloride (manufactured by Tokyo Chemical Industry Co., Ltd.) as a second etching inhibitor, and 0.30 wt% of dihydrazide adipic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a second etching inhibitor, and the mixture was dissolved in the solution to obtain the etching solution composition of Example 23.

[0098] [Example 24] The etching solution composition of Example 24 was prepared by pre-dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 23 and adjusting the concentration of Si derived from silicon nitride in the solution to 200 ppm.

[0099] [Example 25] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 4.00 wt% of 3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a first etching inhibitor, 0.05 wt% of hexachlorodisilane (manufactured by Tokyo Chemical Industry Co., Ltd.) as a second etching inhibitor, and 0.40 wt% of acetohydrazide chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a second etching inhibitor, and the mixture was dissolved in the solution to obtain the etching solution composition of Example 25.

[0100] [Example 26] The etching solution composition of Example 26 was prepared by pre-dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 25 and adjusting the concentration of Si derived from silicon nitride in the solution to 200 ppm.

[0101] [Example 27] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 4.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a first etching inhibitor, 0.05 wt% of hexamethoxydisiloxane (manufactured by Tokyo Chemical Industry Co., Ltd.) having the following chemical structural formula (4) was added as a second etching inhibitor, and 0.40 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. The mixture was then dissolved in the solution to obtain the etching solution composition of Example 27.

[0102] [ka] [Example 28] The etching solution composition of Example 28 was prepared by pre-dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 27 and adjusting the concentration of Si derived from silicon nitride in the solution to 200 ppm.

[0103] [Example 29] 85% phosphoric acid (manufactured by Rasa Industries Co., Ltd.) was diluted to 80% phosphoric acid. To this 80% phosphoric acid, 15.70 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as the first etching inhibitor, 0.50 wt% of tetraethoxysilane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as the second etching inhibitor, and 0.30 wt% of dihydrazide succinate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as the precipitation inhibitor. Dissolving these in the solution prepared the etching solution composition of Example 29.

[0104] [Example 30] The etching solution composition of Example 30 was prepared by pre-dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 29 and adjusting the concentration of Si derived from silicon nitride in the solution to 2500 ppm.

[0105] [Example 31] To 80% phosphoric acid obtained using the same procedure as in Example 29, 15.40 wt% of hydrolyzate of 3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as the first etching inhibitor, 0.40 wt% of tetraethoxysilane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as the second etching inhibitor, and 0.30 wt% of dihydrazide adipic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as the precipitation inhibitor were added, and the mixture was dissolved in the solution to obtain the etching solution composition of Example 31.

[0106] [Example 32] The etching solution composition of Example 32 was prepared by pre-dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 31 and adjusting the concentration of Si derived from silicon nitride in the solution to 3000 ppm.

[0107] [Example 33] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 2.40 wt% of a hydrolysate of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as the first etching inhibitor, 0.30 wt% of the siloxane compound shown in chemical structural formula (2) was added as the second etching inhibitor, and 0.40 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as the precipitation inhibitor. The mixture was then dissolved in the solution to obtain the etching solution composition of Example 33.

[0108] [Example 34] The etching solution composition of Example 34 was prepared by pre-dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 33 and adjusting the concentration of Si derived from silicon nitride in the solution to 400 ppm.

[0109] [Comparative Example 1] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 4.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as the first etching inhibitor, and 0.30 wt% of dihydrazide succinate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. Dissolving these in the solution prepared the etching solution composition of Comparative Example 1.

[0110] [Comparative Example 2] To an 87% phosphoric acid solution obtained using the same procedure as in Example 1, 4.00 wt% of 3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as the first etching inhibitor, and 0.30 wt% of acethydrazide chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. Dissolving these in the solution prepared the etching solution composition of Comparative Example 2.

[0111] [Comparative Example 3] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 4.00 wt% of 3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as the first etching inhibitor, and 0.30 wt% of 2,2-dimethylhydrazide succinate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. Dissolving these in the solution prepared the etching solution composition of Comparative Example 3.

[0112] [Comparative Example 4] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 1.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) and 1.00 wt% of 3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) were added as the first etching inhibitor, and 0.10 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as the precipitation inhibitor. Dissolving these in the solution prepared the etching solution composition of Comparative Example 4.

[0113] [Comparative Example 5] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 3.00 wt% of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as the first etching inhibitor, and 0.30 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. Dissolving these in the solution prepared the etching solution composition of Comparative Example 5.

[0114] [Comparative Example 6] To an 87% phosphoric acid solution obtained using the same procedure as in Example 1, 6.00 wt% of N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as the first etching inhibitor, and 0.30 wt% of acethydrazide chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. Dissolving these in the solution prepared the etching solution composition of Comparative Example 6.

[0115] [Comparative Example 7] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 0.20 wt% of 1,3-dimethyltetramethoxydisiloxane (manufactured by Fluorochem Ltd.), shown in chemical structural formula (1), was added as a second etching inhibitor, and 0.10 wt% of dihydrazide adipic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. After dissolving these in the solution, a predetermined amount of silicon nitride was pre-dissolved, and the concentration of Si derived from silicon nitride in the solution was adjusted to 50 ppm to obtain the etching solution composition of Comparative Example 7.

[0116] [Comparative Example 8] To the 87% phosphoric acid obtained using the same procedure as in Example 1, 0.15 wt% of the siloxane compound shown in chemical structural formula (2) was added as a second etching inhibitor, and 0.10 wt% of dihydrazide adipic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. After dissolving these in the solution, a predetermined amount of silicon nitride was pre-dissolved, and the concentration of Si derived from silicon nitride in the solution was adjusted to 50 ppm to obtain the etching solution composition of Comparative Example 8.

[0117] [Comparative Example 9] To the 87% phosphoric acid obtained using the same procedure as in Example 1, 0.30 wt% of the siloxane compound shown in chemical structural formula (2) was added as a second etching inhibitor, and 0.10 wt% of dihydrazide adipic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. Dissolving these in the solution prepared the etching solution composition of Comparative Example 9.

[0118] [Comparative Example 10] To the 87% phosphoric acid obtained using the same procedure as in Example 1, 0.20 wt% of tetramethoxysilane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a second etching inhibitor, and 0.10 wt% of azelaic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. Dissolving these in the solution prepared the etching solution composition of Comparative Example 10.

[0119] [Comparative Example 11] To the 87% phosphoric acid obtained using the same procedure as in Example 1, 0.30 wt% of tetramethoxysilane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a second etching inhibitor, and 0.10 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. After dissolving these in the solution, a predetermined amount of silicon nitride was pre-dissolved, and the concentration of Si derived from silicon nitride in the solution was adjusted to 50 ppm to obtain the etching solution composition of Comparative Example 11.

[0120] [Comparative Example 12] To the 87% phosphoric acid obtained using the same procedure as in Example 1, 0.50 wt% of tetrabutoxysilane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a second etching inhibitor, and 0.10 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. Dissolving these in the solution prepared the etching solution composition of Comparative Example 12.

[0121] [Comparative Example 13] Comparative Example 13's etching solution composition was prepared by adding 1.00 wt% hexamethyldisiloxane (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 0.10 wt% adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a deposition inhibitor to 87% phosphoric acid obtained using the same procedure as in Example 1, and dissolving them in the solution. Although hexamethyldisiloxane does not qualify as a second etching inhibitor because it does not have four or more alkoxy groups and / or hydroxyl groups in its molecular structure, it is treated as a comparative example and is therefore shown in the "Second Etching Inhibitor" column in Table 2 below.

[0122] [Comparative Example 14] To 80% phosphoric acid obtained using the same procedure as in Example 29, 15.70 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as the first etching inhibitor, and 0.30 wt% of dihydrazide succinate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. Dissolving these in the solution prepared the etching solution composition of Comparative Example 14.

[0123] [Comparative Example 15] To 80% phosphoric acid obtained using the same procedure as in Example 29, 15.40 wt% of hydrolyzate of 3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as the first etching inhibitor, and 0.30 wt% of dihydrazide adipic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as the precipitation inhibitor. Dissolving these in the solution prepared the etching solution composition of Comparative Example 15.

[0124] [Comparative Example 16] To an 87% phosphoric acid obtained using the same procedure as in Example 1, 2.40 wt% of hydrolysate of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added as the first etching inhibitor, and 0.40 wt% of dihydrazide adipic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as the precipitation inhibitor. Dissolving these in the solution prepared the etching solution composition of Comparative Example 16.

[0125] [Comparative Example 17] Comparative Example 17 was obtained by adding 0.30 wt% silicon tetrachloride (manufactured by Tokyo Chemical Industry Co., Ltd.) as a second etching inhibitor and 0.30 wt% dihydrazide adipic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) as a precipitation inhibitor to 87% phosphoric acid obtained using the same procedure as in Example 1, and dissolving them in the solution.

[0126] [Comparative Example 18] To the 87% phosphoric acid obtained using the same procedure as in Example 1, 0.05 wt% of hexachlorodisilane (manufactured by Tokyo Chemical Industry Co., Ltd.) was added as a second etching inhibitor, and 0.40 wt% of acethydrazide chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. Dissolving these in the solution prepared the etching solution composition of Comparative Example 18.

[0127] [Comparative Example 19] To the 87% phosphoric acid obtained using the same procedure as in Example 1, 0.05 wt% of hexamethoxydisiloxane (manufactured by Tokyo Chemical Industry Co., Ltd.), shown in chemical structural formula (4), was added as a second etching inhibitor, and 0.40 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added as a precipitation inhibitor. Dissolving these in the solution prepared the etching solution composition of Comparative Example 19.

[0128] [Reference example 1] The 87% phosphoric acid obtained using the same procedure as in Example 1 was used as the etching solution in Reference Example 1.

[0129] <Etching test> Next, we will describe the etching solution compositions of Examples 1 to 34 and Comparative Examples 1 to 19, as well as the test conditions and measurement methods used in etching tests conducted using the etching solution of Reference Example 1.

[0130] [Test conditions] For etching, test specimens made of silicon nitride (silicon nitride film) and test specimens made of silicon oxide (silicon oxide film) were prepared. Each test specimen was a 1.5 cm x 1.5 cm square. The etching time (t) was 20 minutes for the silicon nitride film and 60 minutes for the silicon oxide film. The etching temperature was 158°C.

[0131] [Method for measuring Si concentration derived from silicon nitride] The Si concentration in the etching solution composition [Si 1a] and the Si concentration in the fatigue solution in which silicon nitride was dissolved in the etching solution composition [Si 1b] were measured, and the Si concentration derived from silicon nitride [Si 1] was determined using the following formula (1). [Si 1] = [Si 1b]―[Si 1a] ···(1) Incidentally, the Si concentration [Si 1a] in the etching solution composition originates from the etching inhibitor contained in the etching solution composition. The Si concentration in the solution was measured using ICP emission spectroscopy (ICP-AES) with a high-resolution ICP emission spectrometer (product name "PS3520", manufactured by Hitachi High-Tech Science Corporation).

[0132] [Method for measuring etching rate] Thickness of silicon nitride film before etching [T 1a ], the thickness of the silicon nitride film after etching [T 1b The following measurements were taken, and the etching rate of silicon nitride [R1] was determined from equation (2) below. [R1] = [T 1a ]-[T 1b ] / t(20 minutes) ···(2) Similarly, the thickness of the silicon oxide film before etching [T 2a ], thickness of silicon oxide film after etching [T 2b The values ​​of ] were measured, and the etching rate of silicon dioxide [R2] was determined from the following equation (3). [R2] = [T 2a ]-[T 2b ] / t(60 minutes) ···(3) The etching rate of silicon nitride [R1] and the etching rate of silicon oxide [R2] were then taken as the selectivity ratio [R1 / R2], which is an indicator of the etching selectivity for silicon nitride. An optical interferometry film thickness monitor (product name "Ava Thinfilm", manufactured by Avantes, resolution 1 nm) was used to measure the film thickness.

[0133] [Evaluation of silica deposition on the surface of silicon oxide films] Thickness of silicon oxide film before etching [T 2a ] and the thickness of the silicon oxide film after etching [T 2b ] difference ([T 2a ]-[T 2b If the film thickness after etching has increased (i.e., the difference is negative), then it can be determined that silica has precipitated on the surface of the silicon oxide.

[0134] The formulations of each etching solution composition for Examples 1 to 34 are shown in Tables 1 and 2 below, and the formulations of each etching solution composition for Comparative Examples 1 to 19 and the formulation of the etching solution for Reference Example 1 are shown in Table 3. Note that the chemical structural formulas (1), (2), (3), and (4) listed in the second etching inhibitor column are the previously mentioned 1,3-dimethyltetramethoxydisiloxane, siloxane compound, or hexamethoxydisiloxane. Tables 1 to 3 also show the results of etching tests conducted using each etching solution composition and etching solution.

[0135] [Table 1]

[0136] [Table 2]

[0137] [Table 3]

[0138] <Consideration> Based on the results of the etching tests described above, the following new findings were obtained regarding the etching solution composition according to the present invention.

[0139] [1] Based on phosphoric acid (inorganic acid), the first etching inhibitor comprises 3-aminopropyltrimethoxysilane or its hydrolysate, 3-aminopropyltriethoxysilane or its hydrolysate, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, or N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane (a first etching inhibitor having three or fewer alkoxy groups, hydroxyl groups, and / or functional groups that are precursors to hydroxyl groups in its molecular structure), 1,3-dimethyltetramethoxydisiloxane, the siloxane compound shown in chemical structural formula (2), the siloxane compound shown in chemical structural formula (3), tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane The etching solution compositions according to Examples 1 to 34, which contain lan, silicon tetrachloride, hexachlorodisilane, or hexamethoxydisiloxane (a second etching inhibitor having four or more alkoxy groups, hydroxyl groups, and / or functional groups that are precursors to hydroxyl groups in its molecular structure) and hydrazides such as adipic acid dihydrazide, succinic acid dihydrazide, acetohydrazide chloride, 2,2-dimethylhydrazide succinate, or azelaic acid dihydrazide (precipitation inhibitor), can keep the etching rate [R2] for silicon oxide low, and as a result, the etching selectivity for silicon nitride films is increased, and a large selectivity ratio [R1 / R2] can be achieved. In a comparison of formulations that did not contain silicon nitride-derived Si in the solution, even the etching solution composition according to Example 15 ([R1 / R2]=143), which had the lowest selectivity ratio, showed a high selectivity ratio [R1 / R2] of approximately 5.3 times that of the etching solution according to Reference Example 1 ([R1 / R2]=27), which consisted only of phosphoric acid (inorganic acid). Furthermore, in the etching solution composition according to Example 16, in which the silicon nitride-derived Si concentration in the solution was set to 200 ppm, the selectivity ratio [R1 / R2] value became ∞ (infinity), and the deposition of silica on the silicon oxide surface was reliably suppressed. This trend was also observed in examples other than the relationship between Example 15 and Example 16.

[0140] [2] Based on phosphoric acid (inorganic acid), the first etching inhibitor is 3-aminopropyltrimethoxysilane or its hydrolysate, 3-aminopropyltriethoxysilane or its hydrolysate, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, or N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane (having three or fewer alkoxy groups, hydroxyl groups, and / or functional groups that are precursors to hydroxyl groups in its molecular structure), and adipic acid dihydrazide, succinate dihydrazide The etching solution compositions of Comparative Examples 1-6 and 14-16, which contain acethydrazide chloride or 2,2-dimethylhydrazide succinate (precipitation inhibitor) but do not contain a second etching inhibitor having four or more alkoxy groups, hydroxyl groups, and / or functional groups that are precursors to hydroxyl groups in their molecular structure, had a large etching rate [R2] for silicon oxide. As a result, they could not improve the etching selectivity for silicon nitride films, and the selectivity ratio [R1 / R2] was 130 or less.

[0141] [3] The etching solution compositions of Comparative Examples 7-12 and 17-19, which are based on phosphoric acid (inorganic acid) and contain 1,3-dimethyltetramethoxydisiloxane, the siloxane compound shown in chemical structural formula (2), tetramethoxysilane, tetrabutoxysilane, silicon tetrachloride, hexachlorodisilane, or hexamethoxydisiloxane (a second etching inhibitor having four or more alkoxy groups, hydroxyl groups, and / or functional groups that are precursors to hydroxyl groups in their molecular structure), and adipic acid dihydrazide or acetohydrazide chloride (precipitation inhibitor), but do not contain a first etching inhibitor having three or fewer alkoxy groups, hydroxyl groups, and / or functional groups that are precursors to hydroxyl groups in their molecular structure, showed a negative etching rate [R2] for silicon oxide, and the deposition of silica on the silicon oxide surface was confirmed. Furthermore, the etching solution composition according to Comparative Example 13, which is based on phosphoric acid (inorganic acid) and contains hexamethyldisiloxane and adipic acid dihydrazide (precipitation inhibitor), only achieved a selectivity ratio ([R1 / R2]=25) similar to that of the etching solution according to Reference Example 1, which consists only of phosphoric acid (inorganic acid).

[0142] [4] From the above results, it has become clear that the etching solution compositions according to Examples 1 to 34 (the present invention) can achieve both high etching selectivity for silicon nitride and suppression of silica deposition on the surface of silicon oxide by simultaneously containing a first etching inhibitor having three or fewer alkoxy groups, hydroxyl groups, and / or functional groups that are precursors of hydroxyl groups in its molecular structure, a second etching inhibitor having four or more alkoxy groups, hydroxyl groups, and / or functional groups that are precursors of hydroxyl groups in its molecular structure, and a precipitation inhibitor containing hydrazides. Furthermore, according to Examples 30 and 32, the etching solution compositions according to the present invention can be used repeatedly even when the concentration of Si derived from silicon nitride in the solution reaches 2500 to 3000 ppm, and in fact, it was found that the selectivity ratio [R1 / R2] can be greatly improved while suppressing silica deposition on the surface of silicon oxide when the concentration of Si derived from silicon nitride in the solution reaches a certain level. Although not shown in the examples, the etching solution composition of the present invention can be used repeatedly even if the concentration of silicon nitride-derived Si in the solution reaches a very high concentration (approximately 3000 ppm), even if the composition is different from that of Examples 30 and 32. [Industrial applicability]

[0143] The etching solution composition according to the present invention is particularly useful in the industrial production of NAND flash memory having a three-dimensional structure (3D NAND), but it can also be used in the industrial production of conventional memory having a two-dimensional structure.

Claims

1. An inorganic acid-based etching solution composition for selectively etching silicon nitride from a semiconductor containing silicon nitride and silicon oxide, An etching inhibitor that suppresses the etching of silicon dioxide, A precipitation inhibitor that suppresses the deposition of silica on the surface of silicon dioxide, and It contains, The etching inhibitor comprises a first etching inhibitor having three or fewer alkoxy groups, hydroxyl groups, and / or functional groups that serve as precursors to hydroxyl groups in its molecular structure, and a second etching inhibitor having four or more alkoxy groups, hydroxyl groups, and / or functional groups that serve as precursors to hydroxyl groups in its molecular structure. The first etching inhibitor is an etching solution composition which is a silane compound having an amino group.

2. An inorganic acid-based etching solution composition for selectively etching silicon nitride from a semiconductor containing silicon nitride and silicon oxide, An etching inhibitor that suppresses the etching of silicon dioxide, A precipitation inhibitor that suppresses the deposition of silica on the surface of silicon dioxide, and It contains, The etching inhibitor comprises a first etching inhibitor having three or fewer alkoxy groups, hydroxyl groups, and / or functional groups that serve as precursors to hydroxyl groups in its molecular structure, and a second etching inhibitor having four or more alkoxy groups, hydroxyl groups, and / or functional groups that serve as precursors to hydroxyl groups in its molecular structure. The aforementioned deposition inhibitor is an etching solution composition containing hydrazides.

3. An inorganic acid-based etching solution composition for selectively etching silicon nitride from a semiconductor containing silicon nitride and silicon oxide, An etching inhibitor that suppresses the etching of silicon dioxide, A precipitation inhibitor that suppresses the deposition of silica on the surface of silicon dioxide, and It contains, The etching inhibitor comprises a first etching inhibitor having three or fewer alkoxy groups, hydroxyl groups, and / or functional groups that serve as precursors to hydroxyl groups in its molecular structure, and a second etching inhibitor having four or more alkoxy groups, hydroxyl groups, and / or functional groups that serve as precursors to hydroxyl groups in its molecular structure. In its unused state, the liquid does not contain silicon nitride-derived Si. An etching solution composition that can be repeatedly used until the concentration of silicon nitride-derived Si in the solution reaches at least 3000 ppm.

4. The etching solution composition according to any one of claims 1 to 3, wherein the first etching inhibitor comprises at least one selected from the group consisting of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and hydrolysates thereof.

5. The etching solution composition according to any one of claims 1 to 3, wherein the second etching inhibitor is a silane compound having at least one functional group selected from the group consisting of alkyl groups, amino groups, and halogen groups.

6. The second etching inhibitor has the following chemical structure (1): The chemical structure of 1,3-dimethyltetramethoxydisiloxane shown below is (2): The siloxane compound shown below has the following chemical structure (3): The siloxane compound shown below has the following chemical structure (4): An etching solution composition according to any one of claims 1 to 3, comprising at least one selected from the group consisting of hexamethoxydisiloxane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, silicon tetrachloride, and hexachlorodisilane.

7. The etching solution composition according to claim 2, wherein the hydrazides include at least one selected from the group consisting of adipic acid dihydrazide, succinic acid dihydrazide, acetohydrazide chloride, 2,2-dimethylhydrazide succinate, and azelaic acid dihydrazide.

8. Etching rate of silicon nitride [R １ ] and the etching rate of silicon dioxide [R ２ The selectivity ratio [R] is the ratio of ] to ]. １ / R ２ The etching solution composition according to any one of claims 1 to 3, wherein the selectivity ratio of the etching solution consisting solely of the inorganic acid is set to 5.3 times or more.

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