Etching solution composition

Abstract

The present invention provides an etching solution composition that can achieve both high etching selectivity for silicon nitride and suppression of silica deposition on the surface of silicon oxide. [Solution] An inorganic acid-based etching solution composition for selectively etching silicon nitride from a semiconductor containing silicon nitride and silicon oxide, the etching solution composition containing (a) an etching inhibitor that inhibits etching of silicon oxide, and (b) a deposition inhibitor that inhibits the deposition of silica on the surface of silicon oxide.

Description

[Technical Field]

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

[0002] The recent trend toward higher integration and capacity in semiconductor circuits has led to a demand for more precise etching technology. For example, in the manufacture of NAND flash memory (3D NAND), which has a three-dimensional structure, silicon nitride and silicon oxide films are alternately stacked and then immersed in an etching solution for etching. However, during this process, it is necessary to precisely remove only the silicon nitride film. Therefore, various etching solutions (compositions) have been developed with the aim of achieving high etching selectivity in the etching process.

[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 containing a solution containing silica and alkali, phosphoric acid, and water. According to Patent Document 1, the use of such an etching solution composition suppresses etching of silicon oxide films and improves etching selectivity for silicon nitride films (see paragraph 0013 of the specification of Patent Document 1).

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

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2020-96160 [Patent Document 2] Japanese Patent Application Publication No. 2018-207108 Summary of the Invention [Problem to be solved by the invention]

[0006] When silicon nitride is etched with an etching solution composition containing phosphoric acid and water, ammonium phosphate [(NH4)3PO4] and silicic acid [SiO x (OH) 4―2x ] n When the concentration of silicic acid in the solution increases, these undergo dehydration condensation to form silica [SiO x This deposit can cause problems such as short circuits and wiring defects in semiconductor products, and 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 and keep the etching rate for silicon oxide low. However, since silicon oxide is also etched by water, when an aqueous etching solution composition is used, it is necessary to consider measures to suppress etching of silicon oxide.

[0008] Regarding the above point, Patent Document 1 states that "etching of silicon oxide films is suppressed and etching selectivity of silicon nitride films is improved," but the details of the mechanism by which this effect is exhibited are unclear (see paragraph 0013 of the same document). Furthermore, because the etching solution composition of 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 more likely to precipitate as silica on the surface of silicon oxide.

[0009] The etching solution composition of Patent Document 2 is said to protect the silicon oxide film by using a hydroxyl group-containing solvent, but the etching selectivity for silicon nitride is not sufficiently high to begin with, and according to the data shown, the highest selectivity ratio between silicon nitride and silicon oxide is only 137 (see Figures 2, 4, and 6 in the same document). Furthermore, Patent Document 2 recognizes that water contained in the etching solution composition functions as a solvent, a residue remover, a viscosity modifier, and a diluent (see paragraph 0021 of the same document), but does not recognize or consider the effect of water on etching silicon oxide.

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

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

[0012] The etching solution composition according to the present invention for solving the above problems has the following characteristic features: 1. An inorganic acid-based etchant composition for selectively etching silicon nitride from a semiconductor comprising silicon nitride and silicon oxide, comprising: (a) an etching inhibitor that inhibits etching of silicon oxide; (b) a precipitation inhibitor that inhibits silica from being precipitated on the surface of silicon oxide; The reason is that it contains

[0013] According to the etching solution composition of this configuration, the etching inhibitor inhibits etching of silicon oxide with water, while silicon nitride is etched primarily with inorganic acid, thereby improving etching selectivity for silicon nitride in semiconductors containing silicon nitride and silicon oxide. Furthermore, the deposition inhibitor inhibits deposition of silica on the silicon oxide surface, thereby preventing defects such as short circuits and wiring failures in semiconductor products.

[0014] In the etching solution composition according to the present invention, the etching inhibitor includes an alkoxysilane or a silane coupling agent; The deposition inhibitor preferably includes a hydrazide.

[0015] The etching solution composition of this configuration contains an etching inhibitor and a precipitation inhibitor that are suitable for use as such, and therefore it is possible to achieve both the effect of the etching inhibitor in inhibiting etching of silicon oxide and the effect of the precipitation inhibitor in inhibiting deposition of silica on the surface of silicon oxide, thereby further improving etching selectivity for silicon nitride.

[0016] In the etching solution composition according to the present invention, The alkoxysilane includes dimethyldimethoxysilane, The silane coupling agent preferably contains N-2-(aminoethyl)-3-aminopropyltrimethoxysilane or 3-aminopropyltrimethoxysilane.

[0017] The etching solution composition of the present invention contains a compound that is particularly suitable as an etching inhibitor, and therefore exhibits an excellent effect of inhibiting etching of silicon oxide.

[0018] In the etching solution composition according to the present invention, The hydrazides preferably include adipic acid dihydrazide, acetohydrazide, succinic acid dihydrazide, or dodecanedioic acid dihydrazide.

[0019] The etching solution composition of this configuration contains a compound that is particularly suitable as a deposition inhibitor, and therefore has an excellent effect of inhibiting silica deposition on the surface of silicon oxide.

[0020] In the etching solution composition according to the present invention, The deposition inhibitor preferably further contains a compound having an imidazole skeleton, a compound having a pyrrolidine skeleton, a phosphonic acid compound, or a compound having a quaternary ammonium skeleton.

[0021] According to the etching solution composition of the present configuration, the precipitation inhibitor contains a second precipitation inhibitor in addition to a hydrazide, and therefore, it is possible to suppress a decrease in the etching rate of silicon nitride while maintaining etching selectivity for silicon nitride even when the solution is fatigued due to etching, which can contribute to extending the life of the etching solution composition and speeding up the etching process.

[0022] In the etching solution composition according to the present invention, the compound having an imidazole skeleton includes imidazole, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium hexafluorophosphate, or 1-ethyl-3-octylimidazolium tetrafluoroborate; The compound having a pyrrolidine skeleton includes 1-butyl-1-methylpyrrolidinium hexafluorophosphate or 1-butyl-1-methylpyrrolidinium tetrafluoroborate, the phosphonic acid compound includes tetrabutylphosphonium bromide; The compound having a quaternary ammonium skeleton preferably includes tetramethylammonium hexafluorophosphate.

[0023] The etching solution composition of the present configuration contains a compound that is particularly suitable as a second precipitation inhibitor, which can further contribute to extending the life of the etching solution composition and speeding up the etching process.

[0024] In the etching solution composition according to the present invention, It is preferable that the liquid can be used until the concentration of Si derived from silicon nitride in the liquid reaches at least 1000 ppm.

[0025] The etching solution composition of this configuration can be used until the concentration of silicon nitride-derived Si in the solution reaches at least 1000 ppm, which significantly extends the solution's lifespan compared to conventional etching solutions (phosphoric acid). Furthermore, a smaller amount of etching can be used to increase the amount of etching, making it very economical and environmentally friendly. Furthermore, the etching inhibitor contained in the etching solution composition inhibits the etching of silicon oxide films, resulting in high etching selectivity for silicon nitride.

[0026] In the etching solution composition according to the present invention, It is preferable that the selectivity [R1 / R2], which is the ratio of the etching rate [R1] of silicon nitride to the etching rate [R2] of silicon oxide, is set to be at least twice the selectivity of the etching solution consisting only of the inorganic acid.

[0027] With the etching solution composition of this configuration, by setting the selectivity [R1 / R2] to at least twice the selectivity of an etching solution consisting only of an inorganic acid, it is possible to perform etching in a short time while achieving both high etching selectivity for silicon nitride and suppression of silica deposition on the silicon oxide surface. DETAILED DESCRIPTION OF THE INVENTION

[0028] An embodiment of the etching liquid composition according to the present invention will be described below, however, it is not intended that the present invention be limited to the following embodiment.

[0029] [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. Each component contained in the etching solution composition will be described below.

[0030] <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. Among these inorganic acids, phosphoric acid is preferred. When used after dilution, phosphoric acid is in the form of an aqueous solution, and its concentration is preferably 50 to 100 wt %, more preferably 85 to 95 wt %. The phosphoric acid may be adjusted to the above-mentioned concentration before use of 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 wt % (strong phosphoric acid) with water at or before use, or dissolving phosphoric anhydride (PO) in water at or before use.

[0031] <Etching inhibitor> The etching solution composition according to the present invention contains an etching inhibitor that inhibits etching of silicon oxide. The content of the etching inhibitor in the etching solution composition is preferably 0.01 to 10% by weight, more preferably 0.1 to 1% by weight. As the etching inhibitor, organosilicon compounds such as alkoxysilanes and silane coupling agents are preferably used.

[0032] [Alkoxysilane] Examples of alkoxysilanes include methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, dimethoxydiphenylsilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, and 1,6-bis(trimethoxysilyl)hexane. The above alkoxysilanes may be used alone or in a mixture of two or more.

[0033] [Silane coupling agents] Examples of silane coupling agents include vinyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-4-aminobutyltrimethoxysilane, N-2-(aminoethyl)-5-aminopentyltrimethoxysilane, N-2-(aminoethyl)-6-aminohexyltrimethoxysilane, and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane. propylmethyldimethoxysilane, 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 the above aminosilanes, tris-(trimethoxysilylpropyl)isocyanurate, 3-mercaptopropylmethyldimethoxysilane, 3-isocyanatopropyltriethoxysilane, and 3-trimethoxysilylpropylsuccinic anhydride.Among these silane coupling agents, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-4-aminobutyltrimethoxysilane, N-2-(aminoethyl)-5-aminopentyltrimethoxysilane, N-2-(aminoethyl)-6-aminohexyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl- N-(butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, and N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane are preferred, and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-4-aminobutyltrimethoxysilane, N-2-(aminoethyl)-5-aminopentyltrimethoxysilane, N-2-(aminoethyl)-6-aminohexyltrimethoxysilane, and 3-aminopropyltrimethoxysilane are more preferred. The above silane coupling agents may be used alone or in a mixture of two or more.

[0034] [Other organosilicon compounds] As the organosilicon compound, in addition to the above-mentioned alkoxysilane and silane coupling agent, silazane, siloxane, etc. can also be used.

[0035] <Deposition inhibitor> The etching solution composition of the present invention contains a precipitation inhibitor that inhibits silica deposition on the surface of silicon oxide. The content of the precipitation inhibitor in the etching solution composition is preferably 0.01 to 5 wt %, more preferably 0.1 to 1 wt %. Preferred 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. The above compounds and compounds may be used alone or in a mixture of two or more. In particular, using two different precipitation inhibitors (a first precipitation inhibitor and a second precipitation inhibitor) can be extremely useful not only in terms of performance in the etching process but also in terms of extending the life of the solution and reducing costs.

[0036] [Hydrazine compounds] Examples of the hydrazine compound 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 monohydrobromide. The above hydrazine compounds may be used alone or in a mixture of two or more.

[0037] [Pyrazoles] Examples of pyrazoles include 3,5-dimethylpyrazole and 3-methyl-5-pyrazole, etc. The above pyrazoles may be used alone or in a mixture of two or more.

[0038] [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. The above triazoles may be used alone or in combination of two or more.

[0039] [Hydrazides] Hydrazides include propionic acid hydrazide, lauric acid hydrazide, salicylic acid hydrazide, formhydrazide, acetohydrazide, p-hydroxybenzoic acid hydrazide, naphthoic acid hydrazide, 3-hydroxy-2-naphthoic acid hydrazide, benzhydrazide, carbodihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, maleic acid dihydrazide, and fumaric acid dihydrazide. , tartaric acid dihydrazide, malic acid dihydrazide, diglycolic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, 2,6-naphthalenedicarboxylic acid dihydrazide, 2,6-naphthoic acid dihydrazide, citric acid trihydrazide, pyromellitic acid trihydrazide, 1,2,4-benzenetricarboxylic acid trihydrazide, nitrilotriacetic acid trihydrazide, 1,3,5-cyclohexanetricarboxylic acid trihydrazide, ethylenediaminetetraacetic acid tetrahydrazide, and 1,4,5,8-naphthoic acid tetrahydrazide. Among these hydrazides, adipic acid dihydrazide is preferred. The above hydrazides may be used alone or in a mixture of two or more.

[0040] [Compounds with an imidazole skeleton] Examples of compounds having an imidazole skeleton include compounds such as imidazole, imidazole carboxylic acid, imido urea, diazolidinyl urea, 3-(2-oxoimidazolidin-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 tetrafluoroborate, and 1-ethyl-3-methylimidazolium hexafluorophosphate. The above compounds having an imidazole skeleton may be used alone or in a mixture of two or more.

[0041] [Compounds with a pyrrolidine skeleton] Examples of compounds having a pyrrolidine skeleton include compounds such as 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 tetrafluoroborate, 1-butyl-1-methylpyrrolidinium tetrafluoroborate, 1-ethyl-1-methylpyrrolidinium hexafluorophosphate, and 1-butyl-1-methylpyrrolidinium hexafluorophosphate. The compounds having a pyrrolidine skeleton may be used alone or in a mixture of two or more.

[0042] [Compounds with a piperidine skeleton] Examples of the compound having a piperidine skeleton include compounds such as piperidine, piperidine-4-carboxylic acid ethyl, piperidin-2-ylacetic acid, and piperidine-4-carboxylic acid methylamide, as well as piperidinium salts such as (piperidinium-1-ylmethyl)trifluoroborate, 1-butyl-1-methylpiperidinium bromide, and 1-butyl-1-methylpiperidinium bisimide. The above-mentioned compounds having a piperidine skeleton may be used alone or in a mixture of two or more.

[0043] [Compounds with a morpholine skeleton] Examples of compounds having a morpholine skeleton include compounds such as morpholine, morpholin-2-ylmethanol, morpholin-3-one, morpholine-4-carbothioic acid amide, morpholin-4-ylacetic acid, and ethyl morpholin-4-ylacetate, as well as morphonium salts such as 4-ethyl-4-methylmorpholinium bromide and 4-(2-ethoxyethyl)-4-methylmorpholinium bisimide. The above-mentioned compounds having a morpholine skeleton may be used alone or in a mixture of two or more.

[0044] [Compounds with a pyridine skeleton] Examples of compounds having a pyridine skeleton include compounds such as 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 tetrafluoroborate, and 1-butyl-pyridium hexafluorophosphate. The above-mentioned compounds having a pyridine skeleton may be used alone or in a mixture of two or more.

[0045] [Phosphonic acid compounds] Examples of the phosphonic acid compound include compounds such as phosphonic acid, diphenyl phosphonate, butyl phosphonate, dipentyl phosphonate, and ammonium phosphate, as well as phosphonium salts such as tetrabutyl phosphonium hexafluorophosphate, tetrabutyl phosphonium bisimide, and tetrabutyl phosphonium bromide. The above phosphonic acid compounds may be used alone or in combination of two or more.

[0046] [Compounds with a quaternary ammonium skeleton] Examples of compounds having a quaternary ammonium skeleton include tetramethylammonium chloride, tetrabutylammonium chloride, tetramethylammonium bromide, tetramethylammonium hydroxide, tetramethylammonium iodide, tetrabutylammonium bromide, tetrabutylammonium hydrogen sulfate, tetramethylammonium hexafluorophosphate, tetrabutylammonium hexafluorophosphate, and choline acetate. The above compounds having a quaternary ammonium skeleton may be used alone or in a mixture of two or more.

[0047] [Compounds with a pyrimidine skeleton] Examples of compounds having a pyrimidine skeleton include thymine, cytosine, uracil, and nucleosides, ribonucleosides, and deoxyribonucleosides of the above-mentioned compounds. The above-mentioned compounds having a pyrimidine skeleton may be used alone or in a mixture of two or more kinds.

[0048] [Compounds with a purine skeleton] Examples of compounds having a purine skeleton include purine, adenine, guanine, uric acid, caffeine, hypoxanthine, xanthine, theophylline, theobromine, isoguanine, and nucleosides, ribonucleotides, and deoxyribonucleotides of the above compounds. The above compounds having a purine skeleton may be used alone or in a mixture of two or more.

[0049] [Compounds with a urea skeleton] Examples of the compound having a urea skeleton include urea, hydroxyurea, N,N-diethylthiourea, N,N-dibutylthiourea, biurea, biuret, N-amidinothiourea, etc. The above-mentioned compounds having a urea skeleton may be used alone or in a mixture of two or more.

[0050] [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 the precipitation inhibitor can be added directly to the inorganic acid, or the etching inhibitor and the precipitation inhibitor may be added to the inorganic acid in a dissolved or suspended state in a solvent. The etching inhibitor and the precipitation inhibitor may be added to the inorganic acid at room temperature or while heating the solution.

[0051] <Solvent> Examples of solvents for dissolving or suspending the etching inhibitor and the precipitation inhibitor include water, alcohols such as methanol, ethanol, 2-propanol, butanol, octanol, benzyl alcohol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, and 2,2,2-trifluoroethanol, ethers such as diethyl ether, diisopropyl ether, dibutyl ether, cyclopentyl methyl ether (CPME), tetrahydrofuran (THF), 2-methyltetrahydrofuran, 1,4-dioxane, and dimethoxyethane, carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and 4-fluoroethylene carbonate, methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, and acetic acid. esters such as butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, and γ-lactone; nitriles such as acetonitrile, propionitrile, valeronitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile, and benzonitrile; amides such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP); ureas such as dimethyl sulfoxide (DMSO), hexamethylphosphoric triamide (HMPA), N,N,N',N'-tetramethylurea (TMU), and N,N'-dimethylpropyleneurea (DMPU); and ionic liquids such as imidazolium salts, pyrrolidinium salts, piperidinium salts, pyridinium salts, morphonium salts, phosphonium salts, quaternary ammonium salts, and sulfonium salts. As for the ionic liquid, examples of the cation include 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, and examples of the anion include Br - , BF4 - , PF6 - , (CN)2N - , Cl - , I - , (CF3SO2)N - , (F2SO2)N - , CH3COO- , HSO4 - , (CH3)2PO4 - , CF3COO - , CH3SO3 - , CF3SO3 - , and SCN - The above solvents may be used alone or in a mixture of two or more.

[0052] <Surfactant> When dissolving or suspending the etching inhibitor and the precipitation inhibitor in a solvent, a surfactant can be used in combination. As the surfactant, any of cationic surfactants, anionic surfactants, amphoteric surfactants, and nonionic surfactants can be used, and these surfactants can also be used in combination.

[0053] The etching solution composition of the present invention has a significant feature in that it can be used within a predetermined concentration range or until the concentration of silicon nitride-derived Si in the solution reaches a predetermined concentration. Conventional etching solutions (phosphoric acid) increase the concentration of silicon nitride-derived Si in the solution as the usage time or number of uses increases. When the Si concentration reaches a certain level, silica precipitation occurs, necessitating the disposal of the etching solution as a fatigue solution or the recovery and regeneration of the fatigue solution. However, the etching solution composition of the present invention can suppress silica precipitation even when the concentration of silicon nitride-derived Si in the solution increases. As a result, the solution life is significantly extended compared to conventional etching solutions (phosphoric acid). Furthermore, the etching process volume can be increased with a small amount of use, making it very economical and environmentally friendly. Furthermore, the etching inhibitor contained in the etching solution composition suppresses etching of silicon oxide films, resulting in high etching selectivity for silicon nitride.

[0054] Here, the concentration (predetermined concentration) of Si derived from silicon nitride in the solution will be explained. As described above, the etching solution composition according to the present invention can be used when the concentration of Si derived from silicon nitride in the solution is within a predetermined concentration range (i.e., it can be used even when the Si concentration, which increases as a result of etching silicon nitride, reaches a significantly higher concentration than conventional concentrations). However, the Si component in the etching solution composition also includes that derived from silane coupling agents, etc. However, silane coupling agents, etc., maintain a stable structure even at any high temperature in the etching solution, and are not involved in the deterioration of the performance of the etching solution composition due to the Si component derived from silane coupling agents, etc., precipitating as silica, etc. Furthermore, the Si component derived from the silicon nitride film is precipitated as silica [SiO x (OH) 4-2x ] n In this case, highly selective etching is possible until the concentration of silicon nitride-derived Si reaches at least 1000 ppm (for example, at any concentration between 1 and 1000 ppm), which is the predetermined concentration. In this specification, the unit (ppm) of the concentration of silicon nitride-derived Si in the etching solution is a unit based on weight (mg / kg).

[0055] 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 [R1] of silicon nitride to the etching rate [R2] of silicon oxide, that is, at least twice as high as that of an etching solution consisting solely of inorganic acid, and thus can exhibit high etching selectivity for silicon nitride. An etching solution composition having such a high selectivity ratio [R1 / R2] can achieve high etching selectivity for silicon nitride while suppressing silica deposition on the silicon oxide surface, and can perform etching in a short time. The selectivity ratio [R1 / R2] of the etching solution composition according to the present invention relative to the selectivity of an etching solution consisting solely of inorganic acid is preferably 6 times or more, and more preferably 9 times or more. Etching using such an etching solution composition having a high selectivity [R1 / R2] relative to an etching solution consisting solely of inorganic acid can prevent defects such as short circuits and wiring defects in semiconductor products, which is extremely advantageous for the industrial production (process) of semiconductor products. [Example]

[0056] An example of the etching solution composition according to the present invention will be described. In this example, an etching test was carried out simulating a part of the manufacturing process of 3D NAND in order to confirm the performance of the etching solution composition.

[0057] <Preparation of Etching Solution Composition 1> As etching solution compositions according to the present invention, etching solution compositions according to Examples 1 to 13 containing an etching inhibitor and a precipitation inhibitor were prepared. For comparison, etching solution compositions according to Comparative Examples 1 to 13 containing only either an etching inhibitor or a precipitation inhibitor were prepared. For reference, an etching solution according to Reference Example 1 containing neither an etching inhibitor nor a precipitation inhibitor was prepared. Hereinafter, the preparation methods of each etching solution composition or etching solution will be described.

[0058] Example 1 An aqueous solution of phosphoric acid (manufactured by Rasa Kogyo Co., Ltd., hereinafter referred to as "85% phosphoric acid") adjusted to a concentration of 85 wt% was used as the base inorganic acid, which was then concentrated to obtain 90% phosphoric acid. 1.00 wt% of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.10 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added to the 90% phosphoric acid and dissolved in the solution to obtain the etching solution composition of Example 1.

[0059] Example 2 A predetermined amount of silicon nitride was dissolved in advance in the etching solution composition of Example 1, and the concentration of Si derived from silicon nitride in the solution was adjusted to 40 ppm to prepare the etching solution composition of Example 2. The concentration of Si derived from silicon nitride in the solution was measured by the "Method for measuring the concentration of Si derived from silicon nitride" described below (the same applies to the following Examples and Comparative Examples).

[0060] Example 3 An etching solution composition of Example 3 was prepared by previously dissolving a predetermined amount of silicon nitride in the etching solution composition of Example 2, and adjusting the concentration of Si derived from silicon nitride in the solution to 80 ppm.

[0061] Example 4 The etching solution composition of Example 4 was prepared by preliminarily 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.

[0062] Example 5 85% phosphoric acid was used as the base inorganic acid, which was then concentrated to 86% phosphoric acid. 10.00 wt% of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) and 1.00 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added to this 86% phosphoric acid and dissolved in a solution. A predetermined amount of silicon nitride was then dissolved in the solution, and the concentration of silicon nitride-derived Si in the solution was adjusted to 1000 ppm. This was used as the etching solution composition of Example 5.

[0063] Example 6 To 90% phosphoric acid obtained by the same procedure as in Example 1, 1.00 wt% of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.10 wt% of dodecanedioic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added, and dissolved in the solution. A predetermined amount of silicon nitride was then dissolved in the solution, and the concentration of Si derived from the silicon nitride in the solution was adjusted to 200 ppm. This was used as the etching solution composition of Example 6.

[0064] Example 7 1.00 wt % of dimethyldimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.10 wt % of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added to 90% phosphoric acid obtained by the same procedure as in Example 1, and dissolved in the liquid to prepare the etching solution composition of Example 7.

[0065] Example 8 An etching solution composition of Example 8 was prepared by preliminarily 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 180 ppm.

[0066] Example 9 To 90% phosphoric acid obtained by the same procedure as in Example 1, 1.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.10 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added, and dissolved in a liquid. A predetermined amount of silicon nitride was then dissolved in the liquid, and the concentration of Si derived from the silicon nitride in the liquid was adjusted to 200 ppm. This was used as the etching solution composition of Example 9.

[0067] Example 10 To 90% phosphoric acid obtained by 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 acetohydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added, and dissolved in a liquid. A predetermined amount of silicon nitride was then dissolved in the liquid, and the concentration of Si derived from the silicon nitride in the liquid was adjusted to 400 ppm. This was used as the etching solution composition of Example 10.

[0068] Example 11 To 90% phosphoric acid obtained by the same procedure as in Example 1, 2.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) and 1.00 wt% of succinic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added, and dissolved in a liquid. A predetermined amount of silicon nitride was then dissolved in the liquid, and the concentration of Si derived from the silicon nitride in the liquid was adjusted to 300 ppm. This was used as the etching solution composition of Example 11.

[0069] Example 12 To 90% phosphoric acid obtained by the same procedure as in Example 1, 4.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.40 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added, and dissolved in the solution. A predetermined amount of silicon nitride was then dissolved in the solution, and the concentration of Si derived from the silicon nitride in the solution was adjusted to 500 ppm. This was used as the etching solution composition of Example 12.

[0070] Example 13 To 86% phosphoric acid obtained by the same procedure as in Example 5, 10.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) and 1.00 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added, and dissolved in a liquid. A predetermined amount of silicon nitride was then dissolved in the liquid, and the concentration of Si derived from the silicon nitride in the liquid was adjusted to 1000 ppm. This was used as the etching solution composition of Example 13.

[0071] Comparative Example 1 The etching solution composition of Comparative Example 1 was prepared by adding 0.01 wt% of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) to 90% phosphoric acid obtained by the same procedure as in Example 1 and dissolving it in the liquid.

[0072] Comparative Example 2 The etching solution composition of Comparative Example 2 was prepared by adding 0.10 wt % of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) to 90% phosphoric acid obtained by the same procedure as in Example 1 and dissolving it in the liquid.

[0073] Comparative Example 3 The etching solution composition of Comparative Example 3 was prepared by adding 1.00 wt% of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) to 90% phosphoric acid obtained by the same procedure as in Example 1 and dissolving it in the liquid.

[0074] Comparative Example 4 To 90% phosphoric acid obtained by 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 and dissolved in a liquid. A predetermined amount of silicon nitride was then pre-dissolved in the solution, and the concentration of Si derived from the silicon nitride in the liquid was adjusted to 500 ppm. This was used as the etching solution composition of Comparative Example 4.

[0075] Comparative Example 5 90% phosphoric acid obtained by the same procedure as in Example 1 was added with 4.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), and dissolved in a liquid. A predetermined amount of silicon nitride was then pre-dissolved in the solution, and the concentration of Si derived from the silicon nitride in the liquid was adjusted to 500 ppm. This was used as the etching solution composition of Comparative Example 5.

[0076] Comparative Example 6 An etching solution composition of Comparative Example 6 was prepared by adding 0.10 wt % adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to 90% phosphoric acid obtained by the same procedure as in Example 1 and dissolving it in the liquid.

[0077] Comparative Example 7 An etching solution composition of Comparative Example 7 was prepared by adding 1.00 wt % adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to 90% phosphoric acid obtained by the same procedure as in Example 1 and dissolving it in the liquid.

[0078] Comparative Example 8 A predetermined amount of silicon nitride was dissolved in 90% phosphoric acid obtained by the same procedure as in Example 1, to which 0.01 wt% adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added, and the resulting solution was adjusted to a concentration of 200 ppm of silicon nitride-derived Si in the solution. This was used as the etching solution composition of Comparative Example 8.

[0079] Comparative Example 9 A predetermined amount of silicon nitride was dissolved in 90% phosphoric acid obtained by the same procedure as in Example 1, to which 0.10 wt% adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added, and the resulting solution was adjusted to a concentration of 200 ppm of silicon nitride-derived Si in the solution. This was used as the etching solution composition of Comparative Example 9.

[0080] Comparative Example 10 1.00 wt % succinic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added to 90% phosphoric acid obtained by the same procedure as in Example 1, and dissolved in the liquid to prepare an etching solution composition of Comparative Example 10.

[0081] Comparative Example 11 An etching solution composition of Comparative Example 11 was prepared by dissolving a predetermined amount of silicon nitride in advance in the etching solution composition of Comparative Example 10, and adjusting the concentration of Si derived from silicon nitride in the solution to 200 ppm.

[0082] Comparative Example 12 An etching solution composition of Comparative Example 12 was prepared by adding 1.00 wt % of acetohydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) to 90% phosphoric acid obtained by the same procedure as in Example 1 and dissolving it in the liquid.

[0083] Comparative Example 13 The etching solution composition of Comparative Example 13 was prepared by dissolving a predetermined amount of silicon nitride in advance in the etching solution composition of Comparative Example 12, and adjusting the concentration of Si derived from silicon nitride in the solution to 200 ppm.

[0084] [Reference example 1] The 90% phosphoric acid obtained in the same manner as in Example 1 was used as the etching solution of Reference Example 1 without further treatment.

[0085] <Etching test 1> Next, the test conditions and measurement methods in Etching Test 1 carried out using the etching solution compositions of Examples 1 to 13 and Comparative Examples 1 to 13, and the etching solution of Reference Example 1 will be described.

[0086] [Test conditions] Test pieces made of silicon nitride (silicon nitride film) and silicon oxide (silicon oxide film) were prepared as etching targets. Each test piece was a 1.5 cm x 1.5 cm square. The etching time (t) was 10 minutes for the silicon nitride film and 30 minutes for the silicon oxide film, but was extended to 60 to 100 minutes as appropriate for those for which the effect was difficult to confirm. The etching temperature was 165°C.

[0087] [Method for measuring the concentration of silicon derived from silicon nitride] The Si concentration [Si 1a] of the etching solution composition and the Si concentration [Si 1b] of the fatigue solution in which silicon nitride was dissolved in the etching solution composition were measured, and the Si concentration [Si 1] derived from silicon nitride was calculated using the following formula (1). [Si 1] = [Si 1b]―[Si 1a] ···(1) The Si concentration [Si 1a] in the etching solution composition is derived from the etching inhibitor contained in the etching solution composition. The Si concentration in the solution was measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES) using a high-resolution ICP atomic emission spectrometer (product name "PS3520", manufactured by Hitachi High-Tech Science Corporation).

[0088] [Method for measuring etching rate] The thickness of the silicon nitride film before etching [T 1a ], the thickness of the silicon nitride film after etching [T 1b The etching rate [R1] of silicon nitride was calculated from the following formula (2). [R1] = [T 1a ]-[T 1b ] / t(10 minutes) ···(2) Similarly, the thickness of the silicon oxide film before etching [T 2a ], the thickness of the silicon oxide film after etching [T 2b The etching rate of silicon oxide [R2] was calculated from the following formula (3). [R2] = [T 2a ]-[T 2b ] / t (30 minutes or 60 minutes to 100 minutes) ... (3) The ratio of the etching rate of silicon nitride [R1] to the etching rate of silicon oxide [R2] was calculated and used as the selectivity ratio [R1 / R2], which is an index of etching selectivity to silicon nitride. The film thickness was measured using an optical interference film thickness monitor (product name "Ava Thinfilm", manufactured by Avantes).

[0089] [Evaluation of Silica Deposition on Silicon Oxide Film Surface] The thickness of the silicon oxide film before etching [T 2a ] and the thickness of the silicon oxide film after etching [T 2b ] and the difference ([T 2a ]-[T 2b]) is calculated, and if the film thickness after etching has increased (if the difference is a negative value), it can be determined that silica has precipitated on the surface of silicon oxide.

[0090] The formulations of the etching solution compositions according to Examples 1 to 13, the formulations of the etching solution compositions according to Comparative Examples 1 to 13, and the formulation of the etching solution according to Reference Example 1, as well as the results of Etching Test 1 carried out using each etching solution composition and etching solution, are summarized in Table 1 below.

[0091] [Table 1]

[0092] <Consideration 1> From the results of the above etching test 1, the following new findings were obtained regarding the etching liquid composition according to the present invention.

[0093] [1] The etching solution compositions according to Examples 1 to 6, which are based on phosphoric acid (inorganic acid) and contain N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (etching inhibitor) and adipic acid dihydrazide or dodecanedioic acid dihydrazide (precipitation inhibitor), the etching solution compositions according to Examples 7 and 8, which are based on phosphoric acid (inorganic acid) and contain dimethyldimethoxysilane (etching inhibitor) and adipic acid dihydrazide (precipitation inhibitor), and the etching solution compositions according to Examples 9 to 13, which are based on phosphoric acid (inorganic acid) and contain 3-aminopropyltrimethoxysilane (etching inhibitor), and adipic acid dihydrazide, acetohydrazide, or succinic acid dihydrazide (precipitation inhibitor), can keep the etching rate [R2] for silicon oxide low. As a result, the etching selectivity for silicon nitride films is increased, and a large selectivity ratio [R1 / R2] can be achieved. In comparison with formulations that did not contain silicon nitride-derived Si in the solution, the selectivity [R1 / R2] of the etching solution composition of the present invention (Example 1) was more than six times higher than that of an etching solution (Reference Example 1) consisting only of phosphoric acid (inorganic acid). The selectivity [R1 / R2] tended to increase as the concentration of silicon nitride-derived Si in the solution increased. Furthermore, the etching solution compositions of Examples 1 to 13 reliably suppressed the deposition of silica on the silicon oxide surface. In particular, the etching solution compositions of Examples 5 and 13, in which the concentration of silicon nitride-derived Si in the solution was set to a high concentration of 1000 ppm, did not exhibit silica deposition on the silicon oxide surface.

[0094] [2] In the etching solution compositions according to Comparative Examples 1 to 5, which are based on phosphoric acid (inorganic acid) and contain N-2-(aminoethyl)-3-aminopropyltrimethoxysilane or 3-aminopropyltrimethoxysilane (etching inhibitors) but do not contain a deposition inhibitor, the etching solution compositions according to Comparative Examples 1 to 3, which do not contain silicon nitride-derived Si in the solution, were unable to sufficiently increase the selectivity [R1 / R2] regardless of the content of the etching inhibitor. Furthermore, excessive etching of silicon oxide was observed, making it difficult to perform high-resolution etching. On the other hand, the etching solution compositions according to Comparative Examples 4 and 5, in which the concentration of silicon nitride-derived Si in the solution was set to 500 ppm, exhibited a negative etching rate [R2] for silicon oxide, and deposition of silica on the silicon oxide surface was confirmed.

[0095] [3] With regard to the etching solution compositions according to Comparative Examples 6 to 13, which are based on phosphoric acid (inorganic acid) and contain adipic acid dihydrazide, succinic acid dihydrazide, or acetohydrazide (precipitation inhibitors) but do not contain an etching inhibitor, the etching solution compositions according to Comparative Examples 6, 7, 10, and 12, which do not contain silicon nitride-derived Si in the solution, were unable to sufficiently increase the selectivity [R1 / R2]. Furthermore, excessive etching of silicon oxide was observed, making it difficult to perform high-resolution etching. On the other hand, the etching solution compositions according to Comparative Examples 8, 9, 11, and 13, in which the concentration of silicon nitride-derived Si in the solution was 200 ppm, exhibited a negative etching rate [R2] for silicon oxide, and deposition of silica on the silicon oxide surface was confirmed.

[0096] [4] From the above results, it is clear that the etching solution compositions (present invention) according to Examples 1 to 13, which contain both an etching inhibitor and a precipitation inhibitor, can achieve both high etching selectivity for silicon nitride and inhibition of silica precipitation on the surface of silicon oxide.

[0097] In order to increase the selectivity [R1 / R2] of an etching solution composition, as shown in the results of Etching Test 1 above, it is effective to keep the etching rate [R2] for silicon oxide low. However, it is essentially necessary to increase the etching rate [R1] for silicon nitride. However, as the concentration of silicon nitride-derived Si in the solution increases (i.e., as solution fatigue progresses), [R1] tends to decrease. Therefore, the inventors conducted further studies and found that when two types of precipitation inhibitors (a first precipitation inhibitor and a second precipitation inhibitor) are used, it is possible to maintain a high [R1] even when the concentration of silicon nitride-derived Si in the solution increases, thereby solving the problem of solution fatigue (extending the solution's life). Below, examples of etching solution compositions according to the present invention using two types of precipitation inhibitors are described.

[0098] <Preparation of Etching Solution Composition 2> As etching solution compositions according to the present invention, etching solution compositions according to Examples 14 to 23 containing an etching inhibitor and two types of precipitation inhibitors were prepared. In Examples 14 to 23, in order to compare with the results of Etching Test 1, a combination of the hydrazides used in Etching Test 1 (first precipitation inhibitor) and another precipitation inhibitor (second precipitation inhibitor) was investigated as the two types of precipitation inhibitors, but the present invention is not limited to this combination. Hereinafter, a method for preparing each etching solution composition or etching solution will be described.

[0099] Example 14 To 90% phosphoric acid obtained by the same procedure as in Example 1, 1.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), 0.20 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 0.10 wt% of imidazole (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and dissolved in a liquid. A predetermined amount of silicon nitride was then dissolved in the liquid, and the concentration of Si derived from the silicon nitride in the liquid was adjusted to 500 ppm. This was used as the etching solution composition of Example 14.

[0100] Example 15 To 90% phosphoric acid obtained by the same procedure as in Example 1, 2.00 wt% of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), 0.20 wt% of succinic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 0.20 wt% of imidazole (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and dissolved in a liquid. A predetermined amount of silicon nitride was then dissolved in the liquid, and the concentration of Si derived from the silicon nitride in the liquid was adjusted to 500 ppm. This was used as the etching solution composition of Example 15.

[0101] Example 16 To 90% phosphoric acid obtained by the same procedure as in Example 1, 1.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), 0.20 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 0.10 wt% of 1-butyl-3-methylimidazolium chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and dissolved in a liquid. A predetermined amount of silicon nitride was then dissolved in the liquid, and the concentration of Si derived from the silicon nitride in the liquid was adjusted to 500 ppm. This was used as the etching solution composition of Example 16.

[0102] Example 17 To 90% phosphoric acid obtained by the same procedure as in Example 1, 2.00 wt% of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), 0.20 wt% of acetohydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 0.20 wt% of 1-butyl-3-methylimidazolium chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added, and dissolved in the solution. A predetermined amount of silicon nitride was then dissolved in the solution, and the concentration of Si derived from the silicon nitride in the solution was adjusted to 500 ppm. This was used as the etching solution composition of Example 17.

[0103] Example 18 To 90% phosphoric acid obtained by the same procedure as in Example 1, 2.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), 0.30 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 0.20 wt% of 1-ethyl-3-methylimidazolium hexafluorophosphate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added, and dissolved in the solution. A predetermined amount of silicon nitride was then dissolved in the solution, and the concentration of Si derived from the silicon nitride in the solution was adjusted to 500 ppm. This was used as the etching solution composition of Example 18.

[0104] Example 19 To 90% phosphoric acid obtained by the same procedure as in Example 1, 2.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), 0.30 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 0.20 wt% of 1-ethyl-3-octylimidazolium tetrafluoroborate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added and dissolved in a liquid. A predetermined amount of silicon nitride was then dissolved in the liquid, and the concentration of Si derived from the silicon nitride in the liquid was adjusted to 500 ppm. This was used as the etching solution composition of Example 19.

[0105] Example 20 To 90% phosphoric acid obtained by the same procedure as in Example 1, 2.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), 0.20 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 0.10 wt% of tetrabutylphosphonium bromide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added, and dissolved in the solution. A predetermined amount of silicon nitride was then dissolved in the solution, and the concentration of Si derived from the silicon nitride in the solution was adjusted to 500 ppm. This was used as the etching solution composition of Example 20.

[0106] Example 21 To 90% phosphoric acid obtained by the same procedure as in Example 1, 2.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), 0.20 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 0.20 wt% of 1-butyl-1-methylpyrrolidinium hexafluorophosphate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added, and dissolved in the solution. A predetermined amount of silicon nitride was then dissolved in the solution, and the concentration of Si derived from the silicon nitride in the solution was adjusted to 500 ppm. This was used as the etching solution composition of Example 21.

[0107] Example 22 To 90% phosphoric acid obtained by the same procedure as in Example 1, 2.00 wt% of 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), 0.30 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 0.20 wt% of 1-butyl-1-methylpyrrolidinium tetrafluoroborate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added, and dissolved in the solution. A predetermined amount of silicon nitride was then dissolved in the solution, and the concentration of Si derived from the silicon nitride in the solution was adjusted to 500 ppm. This was used as the etching solution composition of Example 22.

[0108] Example 23 To 90% phosphoric acid obtained by the same procedure as in Example 1, 2.00 wt% of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), 0.20 wt% of adipic acid dihydrazide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 0.20 wt% of tetramethylammonium hexafluorophosphate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added, and dissolved in the solution. A predetermined amount of silicon nitride was then dissolved in the solution, and the concentration of Si derived from the silicon nitride in the solution was adjusted to 500 ppm. This was used as the etching solution composition of Example 23.

[0109] <Etching test 2> Next, Etching Test 2 was carried out using the etching solutions of Examples 14 to 23. The test conditions, measurement methods, etc. in Etching Test 2 were the same as the test conditions, measurement methods, etc. in Etching Test 1 described above.

[0110] The formulations of the etching solution compositions according to Examples 14 to 23 and the results of Etching Test 2 carried out using the etching solution compositions are summarized in Table 2 below.

[0111] [Table 2]

[0112] <Consideration 2> From the results of Etching Test 2 above, the following further findings were obtained regarding the etching solution composition according to the present invention.

[0113] [5] The etching solution compositions of Examples 14 to 23, which are based on phosphoric acid (inorganic acid) and contain 3-aminopropyltrimethoxysilane or N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (etching inhibitor) and two types of precipitation inhibitors, can maintain a high etching rate [R1] for silicon nitride while keeping the etching rate [R2] for silicon oxide low, even when the solution contains 500 ppm of Si derived from silicon nitride, and therefore can achieve a large selectivity [R1 / R2].

[0114] [6] The etching solution compositions of Examples 18, 19 and 21 to 23, which contain a fluorine-containing group (fluoro-) as one of the two types of precipitation inhibitors, have a particularly high etching rate [R1] for silicon nitride, which can contribute to extending the life of the solution.

[0115] [7] In comparison with the results of Etching Test 1, the etching solution compositions of Examples 14 to 23, which contain an etching inhibitor and two types of precipitation inhibitors, can reduce the content of the etching inhibitor and increase the etching rate [R1] for silicon nitride. This, combined with the extended life of the solution, significantly reduces costs and is extremely useful. [Industrial Applicability]

[0116] The etching solution composition according to the present invention is particularly useful in the industrial production of NAND flash memories having a three-dimensional structure (3D NAND), but can also be used in the industrial production of memories having a conventional two-dimensional structure.

Claims

1. 1. An inorganic acid-based etchant composition for selectively etching silicon nitride from a semiconductor comprising silicon nitride and silicon oxide, comprising: (a) an etching inhibitor that inhibits etching of silicon oxide; (b) Hydrazides as deposition inhibitors that inhibit silica deposition on the surface of silicon oxide An etching solution composition comprising:

2. The etching liquid composition according to claim 1 , wherein the etching inhibitor comprises an alkoxysilane or a silane coupling agent.

3. The alkoxysilane includes dimethyldimethoxysilane, The etching solution composition according to claim 2, wherein the silane coupling agent comprises N-2-(aminoethyl)-3-aminopropyltrimethoxysilane or 3-aminopropyltrimethoxysilane.

4. 4. The etching solution composition according to claim 1, wherein the hydrazides include adipic acid dihydrazide, acetohydrazide, succinic acid dihydrazide, or dodecanedioic acid dihydrazide.

5. 5. The etching solution composition according to claim 1, wherein the precipitation inhibitor further comprises a compound having an imidazole skeleton, a compound having a pyrrolidine skeleton, a phosphonic acid compound, or a compound having a quaternary ammonium skeleton.

6. The compound having an imidazole skeleton includes imidazole, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium hexafluorophosphate, or 1-ethyl-3-octylimidazolium tetrafluoroborate; The compound having a pyrrolidine skeleton includes 1-butyl-1-methylpyrrolidinium hexafluorophosphate or 1-butyl-1-methylpyrrolidinium tetrafluoroborate, the phosphonic acid compound includes tetrabutylphosphonium bromide; The etching solution composition according to claim 5 , wherein the compound having a quaternary ammonium skeleton includes tetramethylammonium hexafluorophosphate.

7. The etching solution composition according to any one of claims 1 to 6, which can be used until the concentration of Si derived from silicon nitride in the solution reaches at least 1000 ppm.

8. Etching rate of silicon nitride [R １ ] and the etching rate of silicon oxide [R ２ ], which is the ratio of １ / R ２ 8. The etching solution composition according to claim 1, wherein the selectivity of the inorganic acid is set to at least twice the selectivity of the etching solution consisting of only the inorganic acid.

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